Influence of the calcium concentration in the presence of organic phosphorus on the physicochemical compatibility and stability of all-in-one admixtures for neonatal use

Background  

Preterm infants need high amounts of calcium and phosphorus for bone mineralization, which is difficult to obtain with parenteral feeding due to the low solubility of these salts. The objective of this study was to evaluate the physicochemical compatibility of high concentrations of calcium associated with organic phosphate and its influence on the stability of AIO admixtures for neonatal use.     

Experimental behaviour of reinforced concrete elements repaired with polymer-modified cementicious mortar

This paper presents the results of experimental tests on flexural behaviour of reinforced concrete beams repaired by polymer-modified mortar. Tests were repeated varying repair thickness, which included or did not include the steel reinforcement. Also the position of repair mortar was varied, as it was carried out either in the tension or compression region. Finally, the reinforcement ratios of beam sections were also varied. Results were compared with those from control beams, which were tested in non-damaged, non-repaired conditions. Thick repairs that include the longitudinal reinforcement can restore the load-bearing capacity and ductility of non-damaged control beams, whether they are applied in the tension or in the compression region. Thin repairs in tension, which substitute the concrete cover, but do not include the reinforcement, can even decrease the load bearing capacity and ductility of the beam, whereas thin repairs in compression are more effective than those in tension.     

Evaluation of the effect of ammonium carbamate on the stability of proteins

BACKGROUND: The use of the volatile salt ammonium carbamate in protein downstream processing has recently been proposed. The main advantage of using volatile salts is that they can be removed from precipitates and liquid effluents through pressure reduction or temperature increase. Although previous studies showed that ammonium carbamate is efficient as a precipitant agent, there was evidence of denaturation in some enzymes. In this work, the effect of ammonium carbamate on the stability of five enzymes was evaluated. RESULTS: Activity assays showed that α‐amylase (1,4‐α–D‐glucan glucanohydrolase, EC 3.2.1.1), lysozyme (1,4‐β‐N‐acetylmuramoylhydrolase, EC 3.2.1.17) and lipase (triacyl glycerol acyl hydrolase, EC 3.1.1.3) did not undergo activity loss in ammonium carbamate solutions with concentrations from 1.0 to 5.0 mol kg^?1, whereas cellulase complex (1,4‐(1,3:14)‐β‐D‐glucan 4‐glucano‐hydrolase, EC 3.2.1.4) and peroxidase (hydrogen peroxide oxidoreductase, EC 1.11.1.7) showed an average activity loss of 55% and 44%, respectively. Precipitation assays did not show enzyme denaturation or phase separation for α‐amylase and lipase, while celullase and peroxidase precipitated with some activity reduction. Analysis of similar experiments with ammonium and sodium sulfate did not affect the activity of enzymes. CONCLUSION: Celullase and peroxidase were denatured by ammonium carbamate. While more systematic studies are not available, care must be taken in designing a protein precipitation with this salt. The results suggest that the generally accepted idea that salts that denature proteins tend to solubilize them does not hold for ammonium carbamate. Copyright © 2010 Society of Chemical Industry     

Studies on the interactions between bovine β-lactoglobulin and chitosan at the solid-liquid interface

Chitosan ultrathin films have been formed on polycrystalline Au substrates using the LbL technique with the purpose of studying its interaction with bovine β-lactoglobulin (β-LG) at the solid-liquid interface. The immobilization of chitosan was followed by Quartz Crystal Microbalance with energy dissipation (QCM-D), Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The behavior of the chitosan films in the presence of β-LG solutions with different bulk concentrations ([β-LG]), ionic strength (I), and pH has been investigated using the same techniques plus Atomic Force Microscopy (AFM). The results showed that for pHs lower than protein's pI, weak intermolecular forces (H bonding, Van der Waals, hydrophobic, etc.) are established between β-LG and chitosan (especially close to the pI) leading to low coverage nonspecific adsorption. On the contrary when pH > pI, strong ionic bonding through attractive electrostatic interactions lead to high coverage adsorbed phases composed of large β-LG aggregates. The adsorption process was shown to consist of a relatively fast step (in which these interactions are predominant) which is followed, once the β-LG monolayer is exceeded, by the slow formation of thicker and increasingly viscoelastic films through β-LG self-aggregation. QCM-D and AFM experiments unveiled the role of [β-LG] and I on the formation of these aggregates. The adsorption isotherm built from impedance data in the medium-low [β-LG] range (0.001-0.3 mg mL⁻¹), showed good fitting to the Langmuir model confirming that the formation of one β-LG monolayer is achieved in this concentration range.     

Novel diol spiro orthocarbonates derived from glycerol as anti‐shrinkage additives for the cationic photopolymerization of epoxy monomers

Shrinkage that takes place during polymerizations induces internal stress in polymeric materials generating a series of problems like poor adhesion to substrates and delamination in coatings or microcracks and microvoids in composites. Some additives like spiro orthocarbonates can reduce or eliminate this shrinkage. This paper deals with the synthesis of novel diol spiro orthocarbonates (DIOL SOCs) and their effect as anti‐shrinkage additives in the photopolymerization of the monomer 3,4‐epoxycyclohexyl‐3′, 4′‐epoxycyclohexanecarboxylate. It was found that increasing the concentration of the DIOL SOCs resulted in higher conversion of the monomer due to the presence of hydroxyl groups. The viscoelastic properties of the polymer products were also measured. It was observed that at 5 mol% of the mixture of DIOL SOCs there was an increase in the storage modulus due to the crosslinking produced by the bifunctional SOCs. However, at higher concentrations, a decrease in the storage modulus was observed. The level of shrinkage using the DIOL SOCs at 20 mol% was reduced by 45% when compared to the case without any additive. DIOL SOCs can be easily prepared by reacting glycerol with tetraethylorthocarbonate. These additives reduced significantly the level of shrinkage of the polyether derived from the diepoxycyclohexane monomer. Copyright © 2010 Society of Chemical Industry     

橡树林中的小教堂 智利Junquillos小教堂

这是一个简单而朴实的教堂设计项目,它坐落在智利南部边远地区的一个小树林中。与很多教堂建设项目一样,建造这个小教堂的预算并不多。但幸运的是,接手这个项目的建筑师Claudio Baladron与Diego Grass成功地向我们展示了如何用最小的预算去建造最具有品质的经典项目。小教堂位于一片幽静的橡树林中,地理     

A LCA (life cycle assessment) of the methanol production from sugarcane bagasse

Nowadays one of the most important environmental issues is the exponential increase of the greenhouse effect by the polluting action of the industrial and transport sectors. The production of biofuels is considered a viable alternative for the pollution mitigation but also to promote rural development. The work presents an analysis of the environmental impacts of the methanol production from sugarcane bagasse, taking into consideration the balance of the energy life cycle and its net environmental impacts, both are included in a LCA (Life Cycle Assessment) approach. The evaluation is done as a case study of a 100,000 t/y methanol plant, using sugarcane bagasse as raw material. The methanol is produced through the BTL (Biomass to Liquid) route. The results of the environmental impacts were compared to others LCA studies of biofuel and it was showed that there are significant differences of environmental performance among the existing biofuel production system, even for the same feedstock. The differences are dependent on many factors such as farming practices, technology of the biomass conversion. With relation to the result of output/input ratio, the methanol production from sugarcane bagasse showed to be a feasible alternative for the substitution of an amount of fossil methanol obtained from natural gas.