RESUMEN

Adhesives that can stick to multiple surface types in underwater and high moisture conditions are critical for various applications such as marine coatings, sealants, and medical devices. The analysis of natural underwater adhesives shows that L-3,4-dihydroxyphenylalanine (DOPA) and functional amyloid nanostructures are key components that contribute to the adhesive powers of these natural glues. The combination of DOPA and amyloid-forming peptides into DOPA-amyloid(-forming peptide) conjugates provides a new approach to design generic underwater adhesives. However, it remains unclear how the DOPA monomers may interact with amyloid-forming peptides and how these interactions may influence the adhesive ability of the conjugates. In this paper, we investigate the behavior of DOPA monomers, (glycine-DOPA)3 chains, and a KLVFFAE and DOPA-glycine chain conjugate in aqueous environments using molecular simulations. The DOPA monomers do not aggregate significantly at concentrations lower than 1.0M. Simulations of (glycine-DOPA)3 chains in water were done to examine the intra-molecular interactions of the chain, wherein we found that there were unlikely to be interactions detrimental to the adhesion process. After combining the alternating DOPA-glycine chain with the amyloid-forming peptide KLVFFAE into a single chain conjugate, we then simulated the conjugate in water and saw the possibility of both intra-chain folding and no chain folding in the conjugate.

RESUMEN

Flue gas from power plants can promote algal cultivation and reduce greenhouse gas emissions(1). Microalgae not only capture solar energy more efficiently than plants(3), but also synthesize advanced biofuels(2-4). Generally, atmospheric CO2 is not a sufficient source for supporting maximal algal growth(5). On the other hand, the high concentrations of CO2 in industrial exhaust gases have adverse effects on algal physiology. Consequently, both cultivation conditions (such as nutrients and light) and the control of the flue gas flow into the photo-bioreactors are important to develop an efficient "flue gas to algae" system. Researchers have proposed different photobioreactor configurations(4,6) and cultivation strategies(7,8) with flue gas. Here, we present a protocol that demonstrates how to use models to predict the microalgal growth in response to flue gas settings. We perform both experimental illustration and model simulations to determine the favorable conditions for algal growth with flue gas. We develop a Monod-based model coupled with mass transfer and light intensity equations to simulate the microalgal growth in a homogenous photo-bioreactor. The model simulation compares algal growth and flue gas consumptions under different flue-gas settings. The model illustrates: 1) how algal growth is influenced by different volumetric mass transfer coefficients of CO2; 2) how we can find optimal CO2 concentration for algal growth via the dynamic optimization approach (DOA); 3) how we can design a rectangular on-off flue gas pulse to promote algal biomass growth and to reduce the usage of flue gas. On the experimental side, we present a protocol for growing Chlorella under the flue gas (generated by natural gas combustion). The experimental results qualitatively validate the model predictions that the high frequency flue gas pulses can significantly improve algal cultivation.

Asunto(s)

Reactores Biológicos , Microalgas/crecimiento & desarrollo , Modelos Biológicos , Dióxido de Carbono/química , Chlorella/crecimiento & desarrollo , Simulación por Computador , Gases/química , Centrales Eléctricas

RESUMEN

Age-related functional decline of the nervous system is consistently observed, though cellular and molecular events responsible for this decline remain largely unknown. One of the most prevalent age-related functional declines is age-related hearing loss (presbycusis), a major cause of which is the loss of outer hair cells (OHCs) and spiral ganglion neurons. Previous studies have also identified an age-related functional decline in the medial olivocochlear (MOC) efferent system prior to age-related loss of OHCs. The present study evaluated the hypothesis that this functional decline of the MOC efferent system is due to age-related synaptic loss of the efferent innervation of the OHCs. To this end, we used a recently-identified transgenic mouse line in which the expression of yellow fluorescent protein (YFP), under the control of neuron-specific elements from the thy1 gene, permits the visualization of the synaptic connections between MOC efferent fibers and OHCs. In this model, there was a dramatic synaptic loss between the MOC efferent fibers and the OHCs in older mice. However, age-related loss of efferent synapses was independent of OHC status. These data demonstrate for the first time that age-related loss of efferent synapses may contribute to the functional decline of the MOC efferent system and that this synaptic loss is not necessary for age-related loss of OHCs.