Wide-band excited and deep-red sensitized Mn2+ emission from an NaSrSc(BO3)2:Eu2+,Mn2+ phosphor with vanished Eu2+ emission.

It is of great importance to develop new broadband red phosphors since they have possible applications like plant cultivation, indoor lighting and non-destructive sensing. Herein, we report a series of Eu2+, Mn2+ activated NaSrSc(BO3)2 phosphors via a conventional solid-state reaction route. It has been found that both Mn2+ and Eu2+ solo-doped NaSrSc(BO3)2 show weak or no luminescence, while Eu2+, Mn2+ co-doped NaSrSc(BO3)2 exhibits wide-band absorption and intense deep-red emission at 680 nm with color purity of 89%. Analysis of the absorption, excitation and emission spectra of Eu2+, Mn2+ solo- and co-doped NaSrSc(BO3)2 indicates that this deep-red broadband emission originates from Eu2+ sensitization of the octahedron Mn2+ 4T1-6A1 transition. It was found that the photoionization process led by energetic similarity of the host band-gap and the Eu2+ lowest 5d excited state was mainly responsible for the vanished luminescence of Eu2+. The values of internal quantum efficiency (IQE) and absorption efficiency (AE) for the optimal NSSO:0.007Eu2+,0.05Mn2+ sample are 24.5% and 61.8%, respectively. This work could provide new insights into exploring novel Mn-activated deep-red luminescent materials.

Function and mechanism of polysaccharide on enhancing tolerance of Trichoderma asperellum under Pb2+ stress.

Trichoderma asperellum ZZY had good tolerance to Pb2+. The polysaccharide contains a functional group which can be effectively combined with metal ions. So in this manuscript, the function and mechanism of polysaccharide on enhancing tolerance of Trichoderma asperellum were further explored. The results indicated that the polysaccharide plays vital role in Pb2+ tolerance of Trichoderma asperellum. Most lead ions adsorbed on and transferred into mycelia were accumulated in the pure polysaccharide. The proportion of uronic acid and the ratio of main chain in pure polysaccharide were increased when the strain under Pb2+ stress. These changes increase the contact area of polysaccharides with Pb2+ and the ratio of carboxyl groups to provide more binding sites for Pb2+, which is beneficial to reduce the amount of free Pb2+ and slow down the toxicity. The response changes in surface morphology and advanced structure of polysaccharide also support the conclusion. The manuscript provided theoretical basis for the application on the remediation of lead pollution. It also had contributions to the remediation of heavy metal pollution in the environment and the environmental safety.

Chemical structure and inhibition on α-glucosidase of the polysaccharides from Cordyceps militaris with different developmental stages.

The natural form of wild edible fungus is the fruiting body. The cultivation of fruiting bodies from sexual reproduction requires strict conditions and long periods. Some literatures have paid attentions on the mycelia prepared with liquid fermentation to alter fruiting bodies. Cordyceps militaris (C. militaris) is a kind of precious edible fungus. The polysaccharide is an important active ingredient in C. militaris. The manuscript aimed to evaluate the feasibility of alternative of mycelia to fruit bodies with studies of polysaccharides from C. militaris of different developmental stages. The two polysaccharides were separated. The chemical structure and inhibitory activity on α-glucosidase of polysaccharides were explored. The results indicated that the structure and inhibitory activity on α-glucosidase of polysaccharides with different developmental stages had significant differences. The polysaccharides from fruiting bodies had better inhibitory activity on α-glucosidase. It demonstrated that the mycelia of C. militaris from asexual reproduction with liquid fermentation can't be an effective substitute for fruiting bodies from sexual reproduction, from the perspective of polysaccharides.

Tolerance mechanism of Trichoderma asperellum to Pb2+: response changes of related active ingredients under Pb2+ stress.

Trichoderma asperellum ZZY has good tolerance to Pb2+, but the tolerance mechanism is not clear. The manuscript aimed to clarify the tolerance mechanism from the perspective of the response changes of related active ingredients. The synthesis of polysaccharides, proteins and thiol compounds in Trichoderma asperellum can be accelerated with Pb2+ stress. Under Pb2+ stress, Trichoderma asperellum can synthesize oxalic acid and secrete it extracellularly. In addition, high concentration of Pb2+ can inhibit the synthesis and extracellular secretion of formic acid and malic acid. The tolerance of Trichoderma asperellum to Pb2+ is the results of multiple reactions. The Pb2+ can promote the synthesis of polysaccharides, proteins, thiol compounds and oxalic acid. In the early stage of Pb2+ stress, Trichoderma asperellum can rapidly initiate an extracellular emergency mechanism, synthesize oxalic acid in mycelia and secrete it extracellularly to remove free Pb2+ and alleviate the toxicity of Pb2+ to cells. With the transport of Pb2+ into cells, it can promote the synthesis of polysaccharides, proteins, thiol compounds to adsorb and transform the Pb2+ and ease the damage to the cells. The manuscript provides theoretical support and scientific explanation for the application of Trichoderma asperellum.

Structural characterization and inhibition on α-glucosidase of the polysaccharides from fruiting bodies and mycelia of Pleurotus eryngii.

The Pleurotus eryngii was chose as research subject to study the similarity and discrepancy of polysaccharides from fruiting body and mycelia, which were named as PEBP-II and PEMP-II, respectively. The purpose is to expand the production and application of Pleurotus eryngii polysaccharide. The molecular weights of PEBP-II and PEMP-II were 4.062 × 106 Da and 4.189 × 106 Da, respectively. The PEBP-II was composed of α-d-Glcp(1→, →6)-ß-d-Galp(1→, →4)-α-d-Glcp(1→, →3,4)-α-d-Glcp(1→ and →3)-α-d-Manp(1→. The PEMP-II was composed of α-d-Glcp(1→, →6)-ß-d-Galp(1→,→4)-α-d-Glcp(1→, →3,4)-α-d-Glcp(1→, →3)-α-d-Manp(1→, →3, 6)-α-d-Manp(1→ and →3)-α-d-Glcp(1→. The PEBP-II and PEMP-II both had dendritic and filamentous structure. The difference of PEBP-II and PEMP-II in structure was the ratio and kinds of backbone and branches. The PEBP-II and PEMP-II had equivalent inhibition on α-glucosidase and can significant inhibit the activity of α-glucosidase with inhibition types of competitive. All the results revealed that the polysaccharides from mycelia can be an effective substitute of polysaccharides from fruiting body. The manuscript expanded the production and application of Pleurotus eryngii polysaccharide. The analysis of chemical structure can provide theoretical basis for exploring the structure-activity relationship of polysaccharides.