Nanjing Tech University

About: Nanjing Tech University is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Catalysis & Membrane. The organization has 21827 authors who have published 21794 publications receiving 364050 citations. The organization is also known as: Nangongda & Nánjīng Gōngyè Dàxúe.

Development of a cooperative two-factor adaptive-evolution method to enhance lipid production and prevent lipid peroxidation in Schizochytrium sp.

Abstract: Schizochytrium sp. is a marine microalga with great potential as a promising sustainable source of lipids rich in docosahexaenoic acid (DHA). This organism’s lipid accumulation machinery can be induced by various stress conditions, but this stress induction usually comes at the expense of lower biomass in industrial fermentations. Moreover, oxidative damage induced by various environmental stresses can result in the peroxidation of lipids, and especially polyunsaturated fatty acids, which causes unstable DHA production, but is often ignored in fermentation processes. Therefore, it is urgent to develop new production strains that not only have a high DHA production capacity, but also possess strong antioxidant defenses. Adaptive laboratory evolution (ALE) is an effective method for the development of beneficial phenotypes in industrial microorganisms. Here, a novel cooperative two-factor ALE strategy based on concomitant low temperature and high salinity was applied to improve the production capacity of Schizochytrium sp. Low-temperature conditions were used to improve the DHA content, and high salinity was applied to stimulate lipid accumulation and enhance the antioxidative defense systems of Schizochytrium sp. After 30 adaptation cycles, a maximal cell dry weight of 126.4 g/L and DHA yield of 38.12 g/L were obtained in the endpoint strain ALE-TF30, which was 27.42 and 57.52% higher than parental strain, respectively. Moreover, the fact that ALE-TF30 had the lowest concentrations of reactive oxygen species and malondialdehyde among all strains indicated that lipid peroxidation was greatly suppressed by the evolutionary process. Accordingly, the ALE-TF30 strain exhibited an overall increase of gene expression levels of antioxidant enzymes and polyketide synthases compared to the parental strain. This study provides important clues on how to overcome the negative effects of lipid peroxidation on DHA production in Schizochytrium sp. Taken together, the cooperative two-factor ALE process can not only increase the accumulation of lipids rich in DHA, but also prevent the loss of produced lipid caused by lipid peroxidation. The strategy proposed here may provide a new and alternative direction for the industrial cultivation of oil-producing microalgae.

A study on upconversion UV–vis–NIR responsive photocatalytic activity and mechanisms of hexagonal phase NaYF4:Yb3+,Tm3+@TiO2 core–shell structured photocatalyst

Abstract: A new core–shell structured composite consisting of upconversion hexagonal phase NaYF4:Yb3+,Tm3+ (simply named NaYF4) microrods and UV–vis–NIR driven anatase TiO2 nanosheets with exposed high-reactive {0 0 1} facets has been prepared and shown to be an advanced NIR and sunlight activated photocatalyst. To understand the nature of NIR-driven photocatalysis of NaYF4@TiO2, various analysis methods are conducted. Structure analysis proved that TiO2 is closely attached on the surface of NaYF4 and can absorb all the converted NIR light (980 nm laser) for photocatalysis. As a result, the new photocatalyst gives higher photocatalytic activity in decomposing phenol and Rhodamine B (RhB) than their physical mixture and pure TiO2 under the NIR and simulated sunlight irradiation. High-reactive hydroxyl radicals ( OH) analysis confirmed the superiority of the core–shell structure and the significant role of the upconversion material in using the NIR light to improve the photocatalytic activity of as-prepared TiO2. Finally, a mechanism for NIR driven photocatalysis is proposed which will help to improve the structure design and functionality of new type of photocatalysts.

Poly(3-hydroxybutyrate) synthesis in fed-batch culture of Ralstonia eutropha with phosphate limitation under different glucose concentrations.

Abstract: Poly(3-hydroxybutyrate) (PHB) was produced by fed-batch cultures of Ralstonia eutropha with phosphate limitation under different glucose concentrations. When glucose was kept at 2.5 g l−1, cell growth and PHB synthesis were limited due to the shortage of carbon source but a higher PHB content occurred in the cell-growth stage. This shows that a low glucose concentration is favorable for PHB accumulation in R. eutropha. PHB obtained with glucose at 9 g l−1 is 1.6 times that obtained with 40 g l−1. When glucose was in the range of 9 to 40 g l−1, PHB concentration and productivity decreased significantly with the increase of glucose concentration. The highest PHB productivity was obtained with glucose at 9 g l−1.

Fast Desalination by Multilayered Covalent Organic Framework (COF) Nanosheets

Abstract: Covalent organic frameworks (COFs) are penetrated with uniform and ordered nanopores, implying their great potential in molecular/ion separations. As an imine-linked, stable COF, TpPa-1 is receiving tremendous interest for molecular sieving membranes. Theoretically, atomically thin TpPa-1 monolayers exhibit extremely high water permeance but unfortunately no rejection to ions because of its large pore size (∼1.58 nm). The COF monolayers tend to stack to form laminated multilayers, but how this stacking influences water transport and ion rejections remains unknown. Herein, we investigate the transport behavior of water and salt ions through multilayered TpPa-1 COFs by nonequilibrium molecular dynamics simulations. By analyzing both the interfacial and interior resistance for water transport, we reveal that with rising stacking number of COF multilayers exhibit increasing ion rejections at the expense of water permeance. More importantly, stacking in the offset eclipsed fashion significantly reduces the equivalent pore size of COF multilayers to 0.89 nm, and ion rejection is correspondingly increased. Remarkably, 25 COF monolayers stacked in this fashion give 100% MgCl2 rejection, whereas water permeance remains 1 to 2 orders of magnitude higher than that of commercial nanofiltration membranes. This work demonstrates the rational design of fast membranes for desalination by tailoring stacking number and fashion of the COF monolayers.