Free Vibrations of Cylindrical Storage Tanks: Finite-Element Analysis and Experiments

This note summarizes a theoretical and experimental study undertaken to provide a deeper understanding of the effect of different parameters on the coupled modal characteristics of circular cylindrical tanks. First, the most common case of clamped-free tanks resting on rigid foundations is investigated by using finite-element (FE) modeling and holographic experiments. A good agreement between experimental and numerical results is a basis to draw a number of conclusions. For both tank geometries investigated, the frequencies for modes of circumferential parameter n = 1 (the “beam” modes) are found to be reduced most significantly by the presence of liquid. Very significant dependence of the radial shell mode shapes on the filling ratio is confirmed both by the FE and experimental results. In addition, nonclassical vibration patterns for radial shell modes were extracted numerically and recorded experimentally. Special attention is paid to the pairs of shell modes. Second, the effects of a flexible foundation and axial compression are investigated using holographic interferometry. The modal responses of this shell–liquid system are found to be different from those of the existing theoretical models.     

Harmonic optical microscopy and fluorescence lifetime imaging platform for multimodal imaging

In this work, we proposed and built a multimodal optical setup that extends a commercially available confocal microscope (Olympus VF300) to include nonlinear second harmonic generation (SHG) and third harmonic generation (THG) optical (NLO) microscopy and fluorescence lifetime imaging microscopy (FLIM). We explored all the flexibility offered by this commercial confocal microscope to include the nonlinear microscopy capabilities. The setup allows image acquisition with confocal, brightfield, NLO/multiphoton and FLIM imaging. Simultaneously, two‐photon excited fluorescence (TPEF) and SHG are well established in the biomedical imaging area, because one can use the same ultrafast laser and detectors set to acquire both signals simultaneously. Because the integration with FLIM requires a separated modulus, there are fewer reports of TPEF+SHG+FLIM in the literature. The lack of reports of a TPEF+SHG+THG+FLIM system is mainly due to difficulties with THG because the present NLO laser sources generate THG in an UV wavelength range incompatible with microscope optics. In this article, we report the development of an easy‐to‐operate platform capable to perform two‐photon fluorescence (TPFE), SHG, THG, and FLIM using a single 80 MHz femtosecond Ti:sapphire laser source. We described the modifications over the confocal system necessary to implement this integration and verified the presence of SHG and THG signals by several physical evidences. Finally, we demonstrated the use of this integrated system by acquiring images of vegetables and epithelial cancer biological samples. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

Water activity and temperature effects on growth of Aspergillus niger, A. awamori and A. carbonarius isolated from different substrates in Argentina

The objectives of this study were to determine the effect of water activity, temperature, and their interactions on a) mycelial growth rate and b) the lag phase prior to grow of seven isolates of Aspergillus section Nigri isolated from peanuts, maize kernels, dried grapes and coffee cherries from Argentina. Three Aspergillus niger, three A. awamori and one A. carbonarius isolates examined showed optimum a(W) level for growth at 0.97 with optimal temperature of 30 degrees C. for most of the isolates and 25 degrees C for only one (A. awamori RCP176). Minimal a(W) for growth was 0.85 at the highest temperature tested. Overall growth was reduced up to 50% at 0.93 a(W). Growth was also to a large extend inhibited at 0.85 a(W) for most isolates even after 21 days of incubation at temperatures lower than 30 degrees C. The analysis of variance of the effect of single (isolate, a(W) and temperature), two- and three-way interaction showed that all factors alone and all interactions were statistically significant (P<0.001) in relation to growth rates and lag phase for A. niger, A. awamori and A. carbonarius isolates. These data are relevant since these species are isolated in high frequency on numerous substrates for human and animal consumption in Argentina.     

Differential selectivity of natural and synthetic aminoglycosides towards the eukaryotic and prokaryotic decoding A sites

The lack of absolute prokaryotic selectivity of natural antibiotics is widespread and is a significant clinical problem. The use of this disadvantage of aminoglycoside antibiotics for the possible treatment of human genetic diseases is extremely challenging. Here, we have used a combination of biochemical and structural analysis to compare and contrast the molecular mechanisms of action and the structure-activity relationships of a new synthetic aminoglycoside, NB33, and a structurally similar natural aminoglycoside apramycin. The data presented herein demonstrate the general molecular principles that determine the decreased selectivity of apramycin for the prokaryotic decoding site, and the increased selectivity of NB33 for the eukaryotic decoding site. These results are therefore extremely beneficial for further research on both the design of new aminoglycoside-based antibiotics with diminished deleterious effects on humans, as well as the design of new aminoglycoside-based structures that selectively target the eukaryotic ribosome.     

Paraquat-loaded alginate/chitosan nanoparticles: preparation, characterization and soil sorption studies

Agrochemicals are amongst the contaminants most widely encountered in surface and subterranean hydrological systems. They comprise a variety of molecules, with properties that confer differing degrees of persistence and mobility in the environment, as well as different toxic, carcinogenic, mutagenic and teratogenic potentials, which can affect non-target organisms including man. In this work, alginate/chitosan nanoparticles were prepared as a carrier system for the herbicide paraquat. The preparation and physico-chemical characterization of the nanoparticles was followed by evaluation of zeta potential, pH, size and polydispersion. The techniques employed included transmission electron microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy. The formulation presented a size distribution of 635 ± 12 nm, polydispersion of 0.518, zeta potential of -22.8 ± 2.3 mV and association efficiency of 74.2%. There were significant differences between the release profiles of free paraquat and the herbicide associated with the alginate/chitosan nanoparticles. Tests showed that soil sorption of paraquat, either free or associated with the nanoparticles, was dependent on the quantity of organic matter present. The results presented in this work show that association of paraquat with alginate/chitosan nanoparticles alters the release profile of the herbicide, as well as its interaction with the soil, indicating that this system could be an effective means of reducing negative impacts caused by paraquat.     

Fibroblast growth factors activate mitogen-activated protein kinase pathways to promote migration in ovine trophoblast cells

Fibroblast growth factors (FGFs) 2 and FGF10 are uterine- and conceptus-derived factors that mediate trophoblast activities in cattle and sheep. To extend our understanding of how FGFs may control peri-implantation development in ruminants, we determined whether FGF2 and FGF10 impact trophoblast cell migration. Transwell inserts containing 8 μm pores were used to examine whether FGF2 or FGF10 supplementation increased oTr1 cell migration. Supplementation with 0.5 ng/ml FGF2 or FGF10 did not affect oTr1 cell migration number, but exposure to 5 or 50 ng/ml FGF2 or FGF10 increased (P<0.05) oTr1 cell migration when compared with controls. The involvement of specific MAP kinase (MAPK) cascades in mediating this FGF response was examined by using pharmacological inhibitors of specific MAPKs. Western blot analysis indicated that FGF2 and FGF10 increased phosphorylation status of MAPKs 1, 3, 8, 9, and 14. Exposure to specific inhibitors blocked FGF induction of each MAPK. Exposure to inhibitors before supplementation with FGF2 or FGF10 prevented FGF induction of cell migration, indicating that each of these signaling molecules was required for FGF effects. A final series of studies examined whether FGF2 and FGF10 also mediated the migration of a bovine trophoblast line (CT1 cell). Increases in migration were detected in each cell line by supplementing 5 or 50 ng/ml FGF2 or FGF10 (P<0.05). In summary, FGF2 and FGF10 regulate migratory activity of ovine trophoblast cells through MAPK-dependent pathways. These outcomes provide further evidence that FGFs function as mediators of peri-implantation conceptus development in cattle and sheep.     

Reduction of the cement content in mortars made with fine concrete aggregates

This study’s main objective is to show the viability of reducing the cement content of mortars by incorporating fine crushed concrete aggregates whilst simultaneously maintaining a good performance in terms of functional requisites. The advantages of this, if the results are positive, are both environmental and economic: less energy is consumed in cement manufacture and the mortars’ direct costs are lower. To evaluate the hypothetical binding characteristics of concrete fines incorporated in mortars, and thus allow a cement consumption reduction, various standard tests were performed to quantify their most important properties (e.g. mechanical strength, water-related performance, cracking susceptibility, shrinkage) and compare them with those of a reference mortar containing no recycled fines and not reducing the cement content.     

Formation of silk fibroin hydrogel and evaluation of its drug release profile

Silk hydrogels are interesting materials to be used as matrix in controlled drug delivery devices. However, methods to accelerate fibroin gelation and allow the drug incorporation during the hydrogel preparation are needed in literature. In this article we report the preparation of silk fibroin hydrogels with addition of several contents of ethanol, used to accelerate fibroin gelation kinetics, and we also evaluate the potential of these hydrogels to be used as matrices for drug delivery. Chemical and conformational properties did not change despite the amount of ethanol incorporated in the hydrogel. Hydrogels containing diclofenac sodium dissolved in ethanol showed a faster initial release of the drug than hydrogels with the drug dissolved in water but equilibrium was reached later. This indicates a more sustained drug delivery from hydrogels in which the model drug was dissolved in ethanol. Fibroin hydrogels confirm their promising use as biopolymeric matrices for controlled drug release. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41802.