Month: February 2020

Pretreatment technologies are necessarily applied to lignocellulosic material to decrease recalcitrance and to improve the yield of fermentable sugars. Many pretreatment methods have been proposed and investigated, such as alkaline, steam explosion, ammonia fiber expansion, organic solvent, dilute acid, and so on. Different pretreatment methods have different mechanisms, for example, they can decrease cellulose crystallinity and/or the polymerization degree, increase accessible surface areas. However, economic and environmental requirements limit the applicability of these methods. An effective pretreatment strategy should also minimize carbohydrate degradation and the production of enzyme inhibitors and toxic products for fermenting microorganisms. One of the most promising pretreatment processes for lignocelluloses material is liquid hot water pretreatment. Some studies have been conducted on the mechanisms of LHW pretreatment. However, different biomass types have different structures and show different reaction mechanisms. In the process of ethanol production from lignocellulosic material, enzymatic hydrolysis and fermentation can be performed separately or simultaneously. In separate hydrolysis and fermentation, these two steps are separate, and SHF can coordinate the inconsistent contradiction between the temperatures for enzymatic hydrolysis and fermentation. In simultaneous saccharification and fermentation, both steps occur in a single bioreactor where the glucose formed is rapidly converted to ethanol by the yeast. However, solid loading is limited by the higher effective mixing and high viscosity of the system in the SSF process. Semi-SSF of ethanol production is an operating mode between SSF and SHF. S-SSF consists of two phases, namely, pre-hydrolysis and SSF. To increase substrate concentration, fed-batch S-SSF process was carried out. Fed-batch S-SSF for ethanol production showed that higher substrate concentration and higher ethanol yield can be obtained compared with S-SSF and SSF when a suitable pre-hydrolytic period is selected. In our previous study, LHW pretreatment was applied to corn stover to test the efficiency of enzymatic hydrolysis, and cellulose conversion rates of almost 100% were obtained. In the present work, corn stover samples were subjected to a combination of LHW pretreatment and fed-batch S-SSF to obtain higher ethanol concentration and yield. The effects of different impact factors on the fermentation digestibility of LHW-pretreated corn stover in S-SSF and fed-batch S-SSF are discussed, and the chemical structures and morphological characteristics of corn stover during LHW pretreatment were presented. A double-blind, randomized, placebo-controlled intervention study recently revealed, that the daily consumption of monomeric and oligomeric flavanols derived from seeds of grapes for 8 weeks accomplish a vascular health benefit in male smokers.

the understanding of cellular and molecular aspects of dopaminergic and glutamatergic receptor interaction, little is known about the interaction between glutamatergic and dopaminergic function in the nAcb during postnatal development. Recent studies have shown that there are important changes in glutamatergic neurotransmission from the day of birth throughout adulthood. Of particular interest is a change in the amplitude of the NMDA receptor-mediated excitatory postsynaptic current to AMPA receptor-mediated EPSC ratio which reaches its maximum toward the end of the second postnatal week and decreases after that until adulthood. In addition to changes in glutamatergic neurotransmission, it has also been found that postnatal development is accompanied by changes in the dopaminergic innervation as well as the density and expression of dopaminergic receptors. The effects of dopamine on glutamatergic neurotransmission have been previously studied. Some studies reported that the activation of D1 receptors enhanced NMDA receptor-mediated EPSCs in dorsal striatal slices, while others reported that D1 receptor agonists attenuated NMDA EPSCs in MS striatal neurons in culture. In the nAcb, some investigators reported that DA or D1 receptor agonists potentiate NMDA receptor-mediated EPSCs in slices, while others reported no significant modulatory effects of DA on NMDA receptor-mediated EPSCs but the presynaptic inhibitory effect of DA on EPSCs was only determined on AMPA/KA receptormediated EPSCs in the nAcb. A substantial effect of DA on pharmacologically isolated NMDA and AMPA/KA receptormediated EPSCs remains to be determined. In a previous study, we showed that acetylcholine presynaptically modulated AMPA/KA and NMDA receptors mediated EPSCs in a parallel fashion in the nAcb during postnatal development. In an effort to clarify how the NMDA and AMPA/KA EPSCs might be affected in the nAcb by dopaminergic innervation, we investigated the effect of DA on NMDA and AMPA/KA excitatory synaptic transmission in this region. Our results demonstrate that DA depresses the excitatory input onto MS neurons by the activation of presynaptic D1-like receptors. While DA depressed the elicited AMPA/KA receptor-mediated EPSCs in MS neurons by 40% of the control, DA almost completely abolished NMDA receptor-mediated EPSC. The effects of DA on glutamatergic EPSCs remained constant throughout the first 3 postnatal weeks. We found that DA inhibited glutamatergic EPSCs in MS neurons recorded in an in vitro slice preparation. Whereas both AMPA/KA and NMDA receptors-mediated components of the EPSCs were significantly inhibited by DA, the inhibition of the NMDA receptor-mediated component was much more pronounced than that of the AMPA/KA receptor-mediated component. Pharmacological evidence suggests that dopaminergic inhibitory effects were mediated by the activation of presynaptic D1-like receptors and that D2-like receptors were not involved.