Designed Additive to Regulated Crystallization for High Performance Perovskite Solar Cell.

It is a crucial role for enhancing the power conversion efficiency (PCE) of perovskite solar cells (PSCs) to prepare high-quality perovskite films, which can be achieved by delaying the crystallization of perovskite film. Hence, we designed difluoroacetic anhydride (DFA) as an additive to regulating crystallization process thus reducing defect formation during perovskite film formation. It was found DFA reacts with DMSO by forming two molecules, difluoroacetate thioether ester (DTE) and difluoroacetic acid (DA). The strong bonding DTE⋅PbI2 and DA⋅PbI2 retard perovskite crystallization process for high-quality film formation, which was monitored through in situ UV/Vis and PL tests. By using DFA additives, we prepared perovskite films with high-quality and low defects. Finally, a champion PCE of 25.28 % was achieved with excellent environmental stability, which retained 95.75 % of the initial PCE after 1152 h at 25 °C under 25 % RH.

Deglycosylation Inactivation Initiated by a Novel Periplasmic Dehydrogenase Complex Provides a Novel Strategy for Eliminating the Recalcitrant Antibiotic Kanamycin.

Biodegradation using enzyme-based systems is a promising approach to minimize antibiotic loads in the environment. Aminoglycosides are refractory antibiotics that are generally considered non-biodegradable. Here, we provide evidence that kanamycin, a common aminoglycoside antibiotic, can be degraded by an environmental bacterium through deglycosylation of its 4'-amino sugar. The unprecedented deglycosylation inactivation of kanamycin is initiated by a novel periplasmic dehydrogenase complex, which we designated AquKGD, composed of a flavin adenine dinucleotide-dependent dehydrogenase (AquKGDα) and a small subunit (AquKGDγ) containing a twin-arginine signal sequence. We demonstrate that the formation of the AquKGDα-AquKGDγ complex is required for both the degradation activity of AquKGD and its translocation into the periplasm. Native AquKGD was successfully expressed in the periplasmic space of Escherichia coli, and physicochemical analysis indicated that AquKGD is a stable enzyme. AquKGD showed excellent degradation performance, and complete elimination of kanamycin from actual kanamycin manufacturing waste was achieved with immobilized AquKGD. Ecotoxicity and cytotoxicity tests suggest that AquKGD-mediated degradation produces less harmful degradation products. Thus, we propose a novel enzymatic antibiotic inactivation strategy for effective and safe treatment of recalcitrant kanamycin residues.

A semi-continuous efficient strategy for removing phosphorus and nitrogen from eel aquaculture wastewater using the self-flocculating microalga Desmodesmus sp. PW1.

The phosphorus content in eel aquaculture wastewater exceeds the discharge standard, and the amount of wastewater discharged is substantial. Therefore, there is an urgent need to explore an economical and efficient method of treating aquaculture wastewater. This study explored the use of Desmodesmus sp. PW1, a type of microalgae, to treat eel aquaculture wastewater. By optimizing the conditions, Desmodesmus sp. PW1 achieved a total phosphorus (TP) removal efficiency of 92.3%, as well as total nitrogen (TN) and ammonia nitrogen (NH4+-N) removal efficiency of 99%, using a photoperiod of 24:0, a temperature of 25 °C, and an inoculation amount of 15%. Furthermore, Desmodesmus sp. PW1 demonstrated a high self-flocculating efficiency (>90%) within 100 min of settling, which facilitated biomass recovery. Subsequently, a semi-continuous treatment process mode was established with a sewage renewal rate of 90%. The results showed that after four rounds of sewage renewal operations, the microalgae biomass in the sewage treatment system could be maintained between 160.0 and 220.0 mg/L, and the average removal rate of TP was 0.13 mg/(L * h). The lipid content of algae cells collected in the semi-continuous treatment system for eel aquaculture wastewater was as high as 36.5%, and the biodiesel properties met the biodiesel standards authorized by Europe and the United States. Overall, this study provides an economical and effective strategy for converting wastewater into high-value microalgae products.

A newly isolated microalga Chlamydomonas sp. YC to efficiently remove ammonium nitrogen of rare earth elements wastewater.

The aim of this study was to establish a practical approach to remove ammonium nitrogen of rare earth elements (REEs) wastewater by an indigenous photoautotrophic microalga. Firstly, a new microalgal strain was successfully isolated from REEs wastewater and identified as Chlamydomonas sp. (named Chlamydomonas sp. YC). The obtained results showed that microalga could completely remove the NH4+-N of 10% REEs wastewater after 10 days of cultivation; however, the highest NH4+-N removal rate was attained by microalga to treat undiluted REEs wastewater. Then, three cultivation modes including batch, semi-continuous and continuous cultivation methods were developed to evaluate the ability of NH4+-N removal rate by this microalga to treat diluted (10%) and undiluted REEs wastewater. It was found that, Chlamydomonas sp. YC exhibited superior performance towards NH4+-N removal rates (32.75-61.05 mg/(L·d)) by semi-continuous and continuous processes for the treatments of 10% and undiluted REEs wastewater in comparison to the results (19.50-30.38 mg/(L·d) by batch process. Interestingly, under the same treatment conditions, among the three cultivation modes, microalga exhibited the highest removal rates of NH4+-N in undiluted REEs wastewater by semi-continuous (61.05 mg/(L·d)) and continuous (57.10 mg/(L·d) processes. In term of the biochemical analysis, microalgal biomass obtained from the wastewater treatment had 35.40-44.40% carbohydrate and 4.97-6.03% lipid, which could be potential ingredients for sustainable biofuels production. And the highest carbohydrate and lipid productivities attained by Chlamydomonas sp. YC in the continuous mode were 226.36 mg/(L·d) and 32.98 mg/(L·d), respectively. Taken together, the established processes mediated with Chlamydomonas sp. YC via continuous cultivation was the great promising approaches to efficiently remove NH4+-N of REEs wastewater and produce valuable biomass for sustainable and renewable biofuels in a simultaneous manner.

Chiral metallic glass nanolattices with combined lower density and improved auxeticity.

Auxetic materials are promising structural and functional candidates due to their unique lateral expansion when stretched, however, bulk metallic glasses (MGs) could not show any auxeticity because of their intrinsic isotropic nature. Here we construct chiral Cu50Zr50 metallic glass nanolattices with cavities, and investigate their auxeticity and underlying mechanism with molecular dynamics simulations. It is found that, compared to monolithic MGs, all the chiral metallic glass nanolattices (CMGNs) exhibit improved auxeticity and lower density. For CMGNs with cavities, the negative Poisson's ratio and ultimate tensile strength (UTS) increase first and then decrease with increasing cavity radius, with the cavity radius of 2.5 nm being the most favorable for auxeticity and enhanced UTS. The auxetic mechanism is attributed to the competition between rotation behavior and non-affine deformation under tension. Our study not only reveals the mechanism of auxeticity in CMGNs having cavities but also provides a feasible method to optimize their auxetic performance and density by structure designing of MGs.

Atomic-level crystallization in selective laser melting fabricated Zr-based metallic glasses.

As a promising additive manufacturing technique, selective laser melting (SLM) provides the possibility of fabricating metallic glassy components free of the constraints of geometrical complexity and dimensions. However, unexpected crystallization greatly affects the microstructure and degrades the mechanical performance of SLM-fabricated metallic glasses (MGs). To clarify the crystallization mechanism and the effect of laser processing on the crystallization, we investigate the atomic-level crystallization in the SLM Zr90Cu10 MG by using molecular dynamics simulations. The results show that crystallization highly related to scan speed lies in the atomic-level cluster changes. Lower scan speed leads to a dramatically increased fraction of the BCC crystal phase, accompanied by the nucleation of a few HCP and FCC crystal phases. As scan speed increases, more icosahedron-like clusters are formed, leading to the formation of the MG, while the nucleation of the crystal phase is suppressed. The suppression of crystallization is further attributed to a higher average temperature variation rate induced by higher scan speed, which reduces the relaxation time, preventing the nucleation and growth of crystal phases. This work contributes to the understanding of the crystallization in MGs during the SLM process at the atomic level, providing guidance to suppress the crystallization in the SLM process of desired metallic glassy components.

A Rapid Method with UPLC for the Determination of Fusaric Acid in Fusarium Strains and Commercial Food and Feed Products.

A rapid, sensitive and validated method for the determination of fusaric acid (FA) in several Fusarium strains and different commercial food and feed products is reported based on ultra-performance liquid chromatography. This method requires only crude sample by a simple extraction with methanol, and requires a very short time of 8 min for completion. Separation of FA was performed at injection volume of 1 µl with a 20:80 (v/v) water/acetonitrile mobile phase containing 0.1 % formic acid at a flow rate of 0.05 ml/min and detected with UV at 220 nm. Nice linearity and good correlation coefficient (R2 > 0.99) were obtained in the concentration range of 1-200 µg/ml. Validation was demonstrated using blank samples spiked at three different concentrations with standard solution, and the method yielded more than 98.2 % recovery efficiencies and below 2.56 % R.S.D. when applied in the analysis of FA produced by Fusarium verticillioides and a set of transgenic strains of this fungus. Satisfactory recoveries in the range of 79.1-105.8 % and R.S.D lower than 10 % were also obtained for the tested commercial food and feed products. The concentration FA detection in the transgenic strains ranged from 9.65 to 135 µg/kg (0.29-4.05 µg per gram of biomass). However, FA was not detected in most of the commercial products with the exception of niblet, oatmeal, red kidney bean and soybean, for which the concentrations of FA ranged from 2.5 to 18 µg/kg (below the permitted maximum). These results show that the proposed method has a great potential application to analyze FA from different sources rapidly.

Optimization of genome shuffling for high-yield production of the antitumor deacetylmycoepoxydiene in an endophytic fungus of mangrove plants.

As an accelerated evolutionary tool, genome shuffling is largely dependent on the high fusion frequency of different parental protoplasts. However, it was unclear how many types of parental protoplasts would afford the highest fusion frequency. Here, we applied the Monte Carlo method to simulate the simplified processes of protoplast fusion, to achieve maximal useful fusions in genome shuffling. The basic principle of this simulation is that valid fusions would take place when the minimum distance between two different types of parent protoplasts is smaller than that between two of the same types. Accordingly, simulations indicated that the highest fusion frequency would be achieved from eight to 12 different parental protoplasts. Based on the simulation results, eight parental protoplasts of the fungal endophyte Phomopsis sp. A123 were subjected to genome shuffling for yield improvement of deacetylmycoepoxydiene (DAM), an antitumor natural product with a novel chemical structure. After only two rounds of genome shuffling, four high-yield DAM-producing strains, namely G2-119, G2-448, G2-866, and G2-919, were obtained with the aid of activity screening and HPLC analysis. The results showed that the DAM yield in these four strains were 243-, 241-, 225-, and 275-fold, respectively, higher than that of the starting strain A123. This is the first time Monte Carlo simulation is introduced into the field of cell fusion and is also the first report on the optimization of genome shuffling focusing on the number of parental types in protoplast fusions.

The origin of enhanced optical absorption of the BiFeO3/ZnO heterojunction in the visible and terahertz regions.

Optical absorption is improved for the BiFeO3/ZnO heterostructure prepared by a sol-gel process, especially, in the terahertz energy region. A dipole-corrected slab model is used to describe the bilayer film, and first-principles calculations agree with the experiments which present unambiguous explanation for the enhancement of the optical properties. Two-dimensional electrons in the ZnO side of the heterostructure are found to play an essential role in forming the photoinduced carriers and the enhancement of the absorption. The conducting layers tend to penetrate into the interface and decrease the band gap, leading to the transport of carriers through the interface to the BiFeO3 side. The photoinduced carriers can be separated by the ferroelectric domains in BiFeO3, and this mechanism makes the heterostructure an ideal candidate for BiFeO3-based ferroelectric photovoltaic cells.

Avertoxins A-D, Prenyl Asteltoxin Derivatives from Aspergillus versicolor Y10, an Endophytic Fungus of Huperzia serrata.

Aspergillus versicolor Y10 is an endophytic fungus isolated from Huperzia serrata, which showed inhibitory activity against acetylcholinesterase. An investigation of the chemical constituents of Y10 led to the isolation of four new prenylated asteltoxin derivatives, named avertoxins A-D (2-5), together with the known mycotoxin asteltoxin (1). In the present study, we report structure elucidation for 2-5 and the revised NMR assignments for asteltoxin and demonstrated that avertoxin B (3) is an active inhibitor against human acetylcholinesterase with the IC50 value of 14.9 µM (huperzine A as the positive control had an IC50 of 0.6 µM). In addition, the cytotoxicity of asteltoxin (1) and avertoxins A-D (2-5) against MDA-MB-231, HCT116, and HeLa cell lines was evaluated.

Real-time response counterattack strategy of tolerant microalgae Chlorella vulgaris MBFJNU-1 in original swine wastewater and free ammonia.

This work was the first time to systematically clarify the potential tolerance mechanism of an indigenous Chlorella vulgaris MBFJNU-1 towards the free ammonia (FA) during the original swine wastewater (OSW) treatment by transcriptome analysis using C. vulgaris UETX395 as the control group. The obtained results showed that C. vulgaris MBFJNU-1 was found to be more resistant to the high levels of FA (115 mg/L) and OSW in comparison to C. vulgaris UETX395 (38 mg/L). Moreover, the transcriptomic results stated that some key pathways from arginine biosynthesis, electron generation and transmission, ATP synthesis in chloroplasts, and glutathione synthesis of C. vulgaris MBFJNU-1 were greatly related with the OSW and FA. Additionally, C. vulgaris MBFJNU-1 in OSW and FA performed similar results in the common differentially expressed genes from these mentioned pathways. Overall, these obtained results deliver essential details in microalgal biotechnology to treat swine wastewater and high free ammonia wastewater.

Pilot-scale remediation of rare earth elements ammonium wastewater by Chlamydomonas sp. YC in summer under outdoor conditions.

This work evaluated the performance of real rare earth elements (REEs) wastewater purification and carbon dioxide (CO2) fixation by Chlamydomonas sp. YC with pilot-scale airlift-photobioreactors (AL-PBRs), tubular photobioreactors (TB-PBRs) and raceway ponds (ORWPs) under high-temperature outdoor conditions in summer. The obtained results showed that Chlamydomonas sp. YC at 1 g/L oyster shell piece (OSP) and 3 % CO2 had the highest biomass (1.9 g/L) and NH4+-N removal efficiency (34.0 %) during the REEs wastewater treatment. Among the selected photobioreactors, Chlamydomonas sp. YC to treat real REEs wastewater at 3 % CO2 under high-temperature outdoor conditions attained the highest biomass (2.3 g/L) in the TB-PBRs with the best NH4+-N removal efficiency (43.0 %). Furthermore, the input cost and CO2 net sequestration evaluation revealed that TB-PBRs was more economical photobioreactors to treat REEs wastewater and fix CO2 by Chlamydomonas sp. YC, providing some vital scientific details for REEs wastewater and CO2 fixation by microalgal biotechnology.

Metagenomics analysis of microbial community distribution in large-scale and step-by-step purification system of swine wastewater.

Biological treatment is one of the most widely used methods to treat swine wastewater in wastewater treatment plants. The microbial community plays an important role in the swine slurry treatment system. However, limited information is available regarding the correlation between pollutant concentration and dominant microbial community in swine wastewater. This work aimed to study the profiling of microbial communities and their abundance in the 40 M3/day large-scale and step-by-step treatment pools of swine wastewater. Metagenome sequencing was applied to study the changes of microbial community structure in biochemical reaction pools. The results showed that in the heavily polluted pools, it was mainly Proteobacteria, Cyanobacteria, Chlorella and other strains that could tolerate high concentration of ammonia nitrogen to remove nitrogen and absorb chemical oxygen demand (COD). In the moderately polluted pools, Nitrospirae, Actinobacteria and other strains further cooperated to purify swine wastewater. In the later stage, the emergence of Brachionus indicated the reduction of water pollution. The dominant microbes and their abundance changed with the purification of swine wastewater in different stages. Moreover, the dominant microflora of swine wastewater treatment pools at all levels reflected little difference in phylum classification level, while in genus classification level, the dominant microflora manifested great difference. Findings demonstrated that the microorganisms maintained ecological balance and absorbed the nutrients in the swine wastewater treatment pools, so as to play the role of purifying sewage. Therefore, the stepwise purification of swine wastewater can be realized by adding bacteria and microalgae of different genera.

A novel and efficient strategy mediated with calcium carbonate-rich sources to remove ammonium sulfate from rare earth wastewater by heterotrophic Chlorella species.

This work was the first time to establish the desired approach with two heterotrophic Chlorella species for ammonium sulfate (AS)-rich rare earth elements (REEs) wastewater treatment by heterotrophic cultivation. The results showed that these two Chlorella species treated by 6 g/L CaCO3 performed the best ability to remove NH4+-N and SO42- of REEs wastewater. Moreover, the established process performed similar features in REEs wastewater treatment by replacing CaCO3 with eggshell powder (ESP) and oyster shell powder (OSP) enriched in CaCO3. Furthermore, microalgae treated by ESP/OSP in a 10-L fermenter showed 837.39 mg/(L·d) NH4+-N and 1,820 mg/(L·d) SO42- removal rates. The developed kinetic models could be well fitted to the experimental data obtained by the 10-L fermenter. Taken together, the established process mediated with two Chlorella species and ESP/OSP by heterotrophic cultivation was the great potential for AS-rich REEs wastewater treatment in a cost-effective manner.

Biosafety evaluation of Nannochloropsis oculata and Schizochytrium sp. oils as novel human milk fat substitutes.

The biosafety assessment of novel human milk fat substitutes (HMFs) from microalgae oils of Nannochloropsis oculata and Schizochytrium sp. was evaluated by testing the cytotoxic activity using IEC-6 cells, and by conducting a sub-chronic 28-day dietary study using Sprague-Dawley (SD) suckling rats in this study. The results of the cytotoxic activity of IEC-6 cells treated with HMFs showed no apparent effect on cell viability at the tested concentrations (0-1000 µg mL-1). For the 28-day sub-chronic study, five rat dietary feeds with 7.5% fat were designed to have the DHA content in the range from 0 to 2.0% using corn oil as a basal oil. After the 28-day treatment, SD rats fed HMFs did not show toxicity signs and adverse effects, based on the results of clinical observation, body weight, food consumption, behavior, hematology, clinical chemistry, and necropsy findings. These results could lead to the conclusion that the inclusion of the new synthesized HMFs into the pre-weaning SD rat diet was acceptable for SD rats and did not exhibit toxic characteristics and adverse features, indicating that the HMFs from microalgal oils were safe and had the potential to be used as a promising feedstock in infant formula.

An integrated semi-continuous culture to treat original swine wastewater and fix carbon dioxide by an indigenous Chlorella vulgaris MBFJNU-1 in an outdoor photobioreactor.

This work was the first time to evaluate the ability of an isolated Chlorella vulgaris MBFJNU-1 to remove nutrients of original swine wastewater (OSW) and fix carbon dioxide (CO2) under outdoor conditions in a simultaneous manner using column photobioreactors. The results showed that microalga cultivated at 3% CO2 in a batch mode achieved the highest biomass and CO2 fixation rate. Then, a semi-continuous process for OSW treatment and CO2 fixation simultaneously by microalga was established and the renewal rate of this process was deeply investigated. Microalga cultivated at 3% CO2 and 80% renewal rate gave the highest productivities of total biomass, CO2 fixation and the greatest average removal rates of total nitrogen, N-NH4+, total phosphorus and chemical oxygen demand. Taken together, C. vulgaris MBFJNU-1 was the promising microalga under outdoor conditions for swine wastewater treatment and CO2 fixation simultaneously for biofuels and biofertilizer production.

Protoplast mutation and genome shuffling induce the endophytic fungus Tubercularia sp. TF5 to produce new compounds.

Tubercularia sp. TF5 is an endophytic fungal strain isolated from the medicinal plant Taxus mairei. Previously, taxol has been detected in the fermentation products of this strain. However, it lost the capability of producing taxol after long-term laboratory culture. Herein, we tried to reactivate the production of taxol by protoplast mutations and genome shuffling. The protoplasts of Tub. sp. TF5 were prepared from its mycelia, and mutated by UV and NTG. The mutant strains regenerated from the mutated protoplasts were selected and classified into four groups on the basis of their phenotypes, the profile of their metabolites analyzed by TLC, MS, and bioassay data. Then, genome shuffling was subsequently carried out with eight mutant strains, with two representatives from each protoplast mutant group, and genome shuffling mutant strains were obtained and screened using the same screening procedure. Although taxol has not been detected in any mutant, two important mutants, M-741 and G-444 were selected for metabolites isolation and determination due to their phenotypes, and differences in TLC analysis result from TF5 and other mutants. Three new sesquiterpenoids, namely tuberculariols A-C (1-3), and a known dihydroisocoumarin (4) were obtained from M-741. Eighteen novel compounds were isolated from G-444, including five new sesquiterpenoids (5-9), two new dihydroisocoumarins (10, 11), one new tetralone (12), together with 10 known compounds (13-20, 1, and 2). The compounds isolated from the M-741 and G-444 were different in structure types and substitutions from those of TF5 (15, 21-29). The results showed, for the first time, that protoplast mutations and genome shuffling are efficient approaches to mining natural products from endophytic fungi. Understanding the mechanisms of unlocking the biosynthesis of new metabolites will facilitate the manipulation of the secondary metabolism in fungi.

Nutrients removal from piggery wastewater coupled to lipid production by a newly isolated self-flocculating microalga Desmodesmus sp. PW1.

A newly isolated microalgal strain, Desmodesmus sp. PW1, possessing not only high potential for removing nitrogen and phosphorous from piggery wastewater but excellent self-flocculating ability, was provided here. Strain PW1 grew well in diluted and undiluted piggery wastewater, and could effectively remove total nitrogen and total phosphorus with removal rates up to 90% and 70%, respectively. In the laboratory scale by 30-L photobioreactor, microalga also performed well in TN (65.3%) and TP (83.5%) removal. Strain PW1 cultivated in the stationary phase achieved high self-flocculating efficiency (>90%) in 2.5 h of settling; meanwhile, temperature and pH slightly influenced on the flocculation. The potential mechanism on self-flocculation was considered related to hydrophobic extracellular polymeric substances. Furthermore, the fatty acid compositions of PW1 were mainly hexadecanoic acid, oleic acid and linoleic acid. Taken together, Desmodesmus sp. PW1 was the promising candidate to overcome the microalgae harvesting problem in piggery wastewater treatment.

Lipid extraction from wet Nannochloropsis biomass via enzyme-assisted three phase partitioning.

A green and efficient enzyme assisted three phase partitioning (EA-TPP) process was firstly developed to extract microalgal lipids using wet Nannochloropsis sp. biomass. In the pretreatment of microalgal biomass by four hydrolytic enzymes, TPP obtained a higher TFAs lipid extraction efficiency by cellulase compared with the resting enzymes. After optimization by EA-TPP of the wet disrupted Nannochloropsis biomass (3 g), the maximum TFAs extraction yield (90.40%) was attained at 20% ammonium sulphate, 6-7 pH, 1:2 slurry/tert-butanol ratio and 70 °C for 2 h incubation time and two extraction cycles. Moreover, results also revealed that the lipidic species compositions of Nannochloropsis sp. biomass were greatly related with the EA-TPP parameters. In the laboratory scale for wet disrupted microalgae biomass, EA-TPP process achieved 88.70% TFAs extraction yield under the optimized conditions. In all, EA-TPP process could be a promising approach to extract microalgae lipids for food application using wet microalgae biomass.

Production of new human milk fat substitutes by enzymatic acidolysis of microalgae oils from Nannochloropsis oculata and Isochrysis galbana.

Human milk fat substitutes (HMFs) with four kinds of n-3 fatty acid for infant formula were firstly synthesized using triacylglycerols (TAGs) from Nannochloropsis oculata rich in PA at the sn-2 position and free fatty acids (FFAs) from Isochrysis galbana rich in n-3 polyunsaturated fatty acids (n-3 PUFAs-ALA/SDA/DHA) via solvent-free acidolysis with Novozym 435, Lipozyme 435, TL-IM and RM-IM as biocatalysts. The results show that the resulting HMFs contain total n-3 PUFA of 13.92-17.12% and PA of 59.38-68.13% at the sn-2 position under the optimal conditions (mole ratio FFAs/TAG 3:1, 60°C (Novozym 435 and Lipozyme TL-IM) and 50°C (Lipozyme 435 and RM-IM), lipase loading 10%, reaction time 24h). Moreover, among the tested enzymes, Lipozyme 435, TL-IM, and RM-IM display the fatty acid selectivity towards SDA, LA and ALA, and OA, respectively. Overall, the examined lipases are promising biocatalysts for producing high-value microalgal HMFs in a cost-effective manner.