1,720,995 research outputs found
Water dynamics in dilute aqueous solutions of small apolar solutes by quasi-elastic neutron scattering
No full textDielectric behavior of lysozyme and ferricytochrome-c in water/ethylene-glycol solutions
No full textBiophys. J
Heat-Denatured Lysozyme Aggregation and Gelation as Revealed by Combined Dielectric Relaxation Spectroscopy and Light Scattering Measurements
No full textThe dielectric behavior of native and heat-denatured lysozyme in ethanol-water solutions was examined in the frequency range from 1 MHz to 2 GHz, using frequency-domain dielectric relaxation spectroscopy. Because of the conformational changes on unfolding, dielectric methods provide information on the denaturation process of the protein and, at protein concentration high enough, on the subsequent aggregation and gelation. Moreover, the time evolution of the 8 protein aggregation and gelation was monitored measuring, by 2 means of dynamic light scattering methods, the diffusion a coefficient of micro-sized polystyrene particles, deliberately added to the protein solution, which act as a probe of the viscosity of the microenvironment close to the particle surface. All together, our measurements indicate that heat-induced denaturation favors, at high concentrations, a protein aggregation process which evolves up to the full gelation of the system. These findings have a direct support from IR measurements of the absorbance of the amide I band that, because of the unfolding, indicate that proteins entangle each other, producing a network structure which evolves, in long time limit, in the gel
Cross-sections for some TpT photoproducts
No full textThe kinetics and cross-sections (probability σ of a photon to give rise to the photochem. event) of some photoproducts of TpT (thymidylylthymidine) irradiated by UV light were studied, based on the reaction scheme of G. E. Johns, et al. (1964). The optical absorbance variations of 2 wavelengths (2650 anad 3250 Å) were measured as a function of the incident dose at 2450 Å. At small doses, a rapid dimer formation and a slower formation of product TpT4 were obsd. The equil. percentage of dimers was calculated to be 12%. The equil. between products TpT4 aad TpT3 was studied by the optical absorbance changes at 3250 Å as a function of the dose at different wavelengths. The cross-section values for TpT4 → TpT3 and TpT3 → TpT4 were calcd. as σ4,3 = 0.24 and σ3,4 = 1.7 cm2μEinstein, resp. The σ4,3 was detd. as a function of the irradn. wavelength and was similar to the TpT4 absorption spectrum. Thus, the quantum yield .vphi.4,3 is nearly const. in the obsd. range. The effect of UV radiation on DNA is discussed
Adaptive Optimization of Hyper-Parameters for Robotic Manipulation through Evolutionary Reinforcement Learning
No full textDeep Reinforcement Learning applications are growing due to their capability of teaching the agent any task autonomously and generalizing the learning. However, this comes at the cost of a large number of samples and interactions with the environment. Moreover, the robustness of learned policies is usually achieved by a tedious tuning of hyper-parameters and reward functions. In order to address this issue, this paper proposes an evolutionary RL algorithm for the adaptive optimization of hyper-parameters. The policy is trained using an on-policy algorithm, Proximal Policy Optimization (PPO), coupled with an evolutionary algorithm. The achieved results demonstrate an improvement in the sample efficiency of the RL training on a robotic grasping task. In particular, the learning is improved with respect to the baseline case of a non-evolutionary agent. The evolutionary agent needs 60% fewer samples to completely learn the grasping task, enabled by the adaptive transfer of knowledge between the agents through the evolutionary algorithm. The proposed approach also demonstrates the possibility of updating reward parameters during training, potentially providing a general approach to creating reward functions
L’approccio combinato nel trattamento dell’incontinenza fecale da lesione sfinterica: la sfinteroplastica diretta riabilitata
No full textInteraction cetyltrimethylammonium bromide – DNA investigated by dielectric spectroscopy
No full textInfluence of urea on thermal denaturation of lysozyme investigated by optical and dielectric spectroscopies
No full textPhys. Chem. Chem. Phys
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