A study is made of the effects of storage (time and temperature) on the lipid fraction of four milk‐based adapted infant formulas with basically the same composition, though differing in the iron salt added (lactate or sulfate) and/or the vitamin E source (α‐tocopherol or α‐tocopherol acetate). Peroxide value, hydroperoxide C18 percentage and thiobarbituric acid‐reactive substance (TBARS) content were used as indicators of lipid peroxidation. Fat contents remained stable throughout storage. Peroxide values increased from the first storage month and were affected by storage time, although they exhibited irregular behavior. Storage time and temperature affected hydroperoxide percentage, which was seen to be the earliest indicator of lipid oxidation, being measurable in newly manufactured formulas. TBARS values were only affected by storage time. No statistically significant differences were found among the four infant formulas for any of the lipid oxidation indicators. 相似文献
In the present work, the preparation, characterisation, and efficiency of two different silica nanostructures as release vehicles of Cisplatin are reported. The 1‐hexadeciltrimethyl‐ammonium bromide templating agent was used to obtain mesoporous silica nanoparticles which were later loaded with Cisplatin. While sol–gel silica was very fast prepared using an excess of acetic acid during the hydrolysis–condensation reactions of tetraethylorthosilicate and at the same time the Cisplatin was added. Several physicochemical techniques including spectroscopies, electronic microscopy, X‐ray diffraction, N2 adsorption–desorption were used to characterise the silica nanostructures. An in vitro Cisplatin release test was carried out using artificial cerebrospinal fluid. Finally, the toxicity of all silica nanostructures was tested using the C6 cancer cell line. The spectroscopic results showed the suitable stabilisation of Cisplatin into the two different silica nanostructures. A large surface area was obtained for the mesoporous silica nanoparticles, while low areas were obtained in the silica nanoparticles. Cisplatin was released faster from mesoporous silica channels than from inside of aggregates nanoparticles silica. Cisplatin alone, as well as, cisplatin released from both silica nanostructures exerted a toxic effect on cancer cells. In contrast, both silica structures without the drug did not exert any toxic effect.Inspec keywords: cellular biophysics, desorption, adsorption, biomedical materials, sol‐gel processing, silicon compounds, cancer, toxicology, nanofabrication, brain, condensation, mesoporous materials, nanoparticles, X‐ray diffraction, nanomedicine, drugs, aggregates (materials)Other keywords: mesoporous silica channels, silica‐based nanoparticles, cancer brain cells, silica nanostructures, 1‐hexadeciltrimethyl‐ammonium bromide, mesoporous silica nanoparticles, sol‐gel silica, C6 cancer cell line, in vitro cisplatin release test, C6 cancer cell line, acetic acid, hydrolysis‐condensation reactions, tetraethylorthosilicate, physicochemical techniques, electronic microscopy, X‐ray diffraction, N2 adsorption‐desorption, artificial cerebrospinal fluid, toxicity, toxic effect, N2 , SiO2相似文献
The electrochemical behaviour of an AZ91 magnesium alloy was investigated in a low aggressive medium by means of local and global electrochemical impedance measurements. The results were compared to those obtained on a pure magnesium sample. It was possible to show the individual contribution of each phase constituting the alloy, and it was observed that the corrosion mechanism of the two phases was the same, controlled by the Mg dissolution. However, local impedance diagrams clearly indicated that the kinetics dissolution of the β-phase was slower than that of the α-phase, which was in good agreement with SEM observations. 相似文献
Comments on the special issue of the American Psychologist (2000[Jan], Vol 55[1]) on positive psychology. The author points out that in this special issue the perspectives of psychologists of color were not represented. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
This study presents the results of a new visual procedure designed to generate affective learning, namely the change in the affective rating of a previously. neutral stimulus by simply pairing it with a liked or disliked stimulus. Specifically, an experiment was conducted to evaluate the effect of nonreinforced preexposures to the to-be-conditioned stimulus (a non-sense shape) on affective conditioning. This manipulation, intended to produce latent inhibition, typically results in retarded learning when the preexposed stimulus is paired with the unconditioned stimulus. The results revealed that it is possible to modify the affective value of a previously neutral non-sense shape by pairing it with a liked or disliked unconditioned stimulus, and that latent inhibition affects affective conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
A simple, easily accessible solvent‐free method for the dispersion of MWCNTs into PET is proposed, based on the preparation of a microparticulate polymer/nanotube masterbatch via cryogenic impact‐milling and its subsequent melt blending with the bulk polymer. Thermal and mechanical properties of nanocomposites prepared using this method were evaluated as a function of nanotube concentration. Thermal stability was improved, and superior crystallization behavior of PET in the nanocomposites was observed. Significant improvements of around 25% in tensile strength and tensile modulus of the nanocomposites was achieved using this strategy, with only 0.25 wt.‐% MWCNT, compared to previous literature data where 1 wt.‐% MWCNT was employed.
The ability of dendrimer 2G‐[Si{O(CH2)2N(Me)2+(CH2)2NMe3+(I?)2}]8 (NN16) to transfect a wide range of cell types, as well as the possible biomedical application in direct or indirect inhibition of HIV replication, was investigated. Cells implicated in HIV infection such as primary peripheral blood mononuclear cells (PBMC) and immortalized suspension cells (lymphocytes), primary macrophages and dendritic cells, and immortalized adherent cells (astrocytes and trophoblasts) were analyzed. Dendrimer toxicity was evaluated by mitochondrial activity, cell membrane rupture, release of lactate dehydrogenase, erythrocyte hemolysis, and the effect on global gene expression profiles using whole‐genome human microarrays. Cellular uptake of genetic material was determined using flow cytometry and confocal microscopy. Transfection efficiency and gene knockdown was investigated using dendrimer‐delivered antisense oligonucleotides and small interfering RNA (siRNA). Very little cytotoxicity was detected in a variety of cells relevant to HIV infection and erythrocytes after NN16 dendrimer treatment. Imaging of cellular uptake showed high transfection efficiency of genetic material in all cells tested. Interestingly, NN16 further enhanced the reduction of HIV protein 24 antigen release by antisense oligonucleotides due to improved transfection efficiency. Finally, the dendrimer complexed with siRNA exhibited therapeutic potential by specifically inhibiting cyclooxygenase‐2 gene expression in HIV‐infected nervous system cells. NN16 dendrimers demonstrated the ability to transfect genetic material into a vast array of cells relevant to HIV pathology, combining high efficacy with low toxicity. These results suggest that NN16 dendrimers have the potential to be used as a versatile non‐viral vector for gene therapy against HIV infection.相似文献
A small-scale glue laminated timber (GLT) model plant, capable of producing an average of 880 linear m of lamellas per day, approximately 1500 m3/year, located in Castilla y León, Spain, was technically and economically evaluated. The production of such plant is aimed at substituting imports of GLT manufactured from spruce in Central Europe. The total investment considered for this theoretical operation was 455 k€. The raw material proposed was Pinus sylvestris classified according to UNE 56544 as ME-2. The external lamellas were defined as ME-1, upgraded from ME-2 by the removal of knots and deformations, which gives an average block length of 1825 and 3800 mm for external and internal lamellas, respectively. The effective stiffness of such configuration was modeled, rendering beams that could be assigned to class resistance GL24. Production costs were 770 k€, 52% of which were timber as raw material. The volume of production is affected by the combination of products manufactured; therefore, this variable was presented as a function of economic result, defining zones of product-mix that would be economically unfeasible, feasible with reservations, and feasible. The products to be manufactured were straight beams, 6-m long, of 9 different cross-sections, varying from 80?×?120 mm2 to 200?×?600 mm2. Additionally, production volume, wood cost, and block length are identified as critical parameters for the sensitivity analysis of the plant. Considering a wood cost for ME-2 of 220 €/m3, the plant must operate at 70% of its capacity to be economically feasible. The economic result of the operation increases proportionally to block length. The plant generates an EBIT of 51 k€, PNV of 415 k€ (discount rate of 4%), and an IRR of 19%.