Mild O2-aided alkaline pretreatment effectively improves fractionated efficiency and enzymatic digestibility of Napier grass stem towards a sustainable biorefinery.

Napier grass is a promising energy source on account of its strong adaptability and high productivity. Herein, an O2-aided alkaline pretreatment with mild operating conditions was developed to modify Napier grass stem structure for improving its fractionated efficiency and enzymatic digestibility. Compared with the conventional alkaline pretreatment, it could be proceeded at lower temperature (80 °C) and dilute NaOH solution (1%) to remove over 80% lignin and retain 92% cellulose. The recovered lignin possessed typical structures of native lignin and well-preserved molecular weight, anticipating feasible potential in preparation of biomaterials or aromatic chemicals. Coupled with the enzymatic hydrolysis managements of solid remain and hydrolysate after the pretreatment, the recovery yields of glucose and xylose based on the raw material feeds reached 89.7% and 90.2%, respectively. This contribution demonstrates a highly-reliable strategy to fractionate Napier grass stem for maximizing fermentation sugar production and valorizing lignin toward sustainable biorefinery processes.

[Effect of the Cu+ concentration on the curve of thermoluminescence of ZnS:Cu electroluminescent material].

In the paper, five ZnS:Cu electroluminescent material specimens were prepared by adding 0.05%, 0.10%, 0.15%, 0.20% and 0.25% Cu+ to ZnS. From the sample's thermoluminescence curve and luminance, the authors can see that with the variation of Cu+ concentration, the peak of thermoluminescence curve changed correspondingly. At first with the increase of Cu+ concentration, the peak of thermoluminescence curve rised gradually. When the Cu+ concentration was 0.05%, the peak of thermoluminescence curve was 124.15 which attainded max, when the Cu+ concentration was 0.25%, the peak of the curve of thermoluminesence forther decreased to 51. But the temperature corresponding to the peak of the curves of thermoluminesence didn' change, which means that the depth of electron trap did not vary. The authors therefore conclude that excessive Cu+ results in a decline of luminance because the energy of trapped electrons turns into the transition without radiation, though the probability of trapping electrons increases and the life of photoelectrons shortens as the luminescence center increases. In this way, there is an optimal value for Cu+ concentration, which leads to the peak of the curves of thermoluminesence and the maximum of luminance.