Separating and characterizing functional alkane degraders from crude-oil-contaminated sites via magnetic nanoparticle-mediated isolation

Uncultivable microorganisms account for over 99% of all species on the planet, but their functions are yet not well characterized. Though many cultivable degraders for n-alkanes have been intensively investigated, the roles of functional n-alkane degraders remain hidden in the natural environment. This study introduces the novel magnetic nanoparticle-mediated isolation (MMI) technology in Nigerian soils and successfully separates functional microbes belonging to the families Oxalobacteraceae and Moraxellaceae, which were dominant and responsible for alkane metabolism in situ. The alkR-type n-alkane monooxygenase genes, instead of alkA- or alkP-type, were the key functional genes involved in the n-alkane degradation process. Further physiological investigation via a BIOLOG PM plate revealed some carbon (Tween 20, Tween 40 and Tween 80) and nitrogen (tyramine, L-glutamine and D-aspartic acid) sources promoting microbial respiration and n-alkane degradation. With further addition of promoter carbon or nitrogen sources, the separated functional alkane degraders significantly improved n-alkane biodegradation rates. This suggests that MMI is a promising technology for separating functional microbes from complex microbiota, with deeper insight into their ecological functions and influencing factors. The technique also broadens the application of the BIOLOG PM plate for physiological research on functional yet uncultivable microorganisms

Response of soil bacterial community composition and its associated geochemical parameters to rapid short-term cyclic groundwater-level oscillations: soil column experiments

Groundwater-level oscillations change geochemical conditions, carbon cycling processes and bacterial community composition, and these changes may vary vertically with depth in a soil. In this study, soil column experiments were conducted to explore variations in soil bacterial community composition and its associated geochemical parameters to rapid short-term cyclic groundwater-level oscillations driven by natural fluctuations (NF) and rainfall infiltration (RI) and the results are compared with quasi static (QS) column. Water saturation patterns in vadose and oscillated zones, and oxygen level patterns, soil total organic carbon (TOC) removal rates and soil bacterial community composition in vadose, oscillated and saturated zones were evaluated. Results showed that water saturation and oxygen level oscillated with groundwater level in NF and RI columns. TOC removal rates in RI column were the highest across vadose (~38.4%), oscillated (~35.8%) and saturated (~35.2%) zones. Deltaproteobacteria, which was significantly correlated with TOC removal (p < 0.05), exhibited relatively higher abundances in the vadose and oscillated zones of RI column than those of QS and NF columns. Soil bacterial community structure was dynamic at the class level due to water saturation, oxygen level and TOC removal. TOC removal was the driver to separate distribution of bacterial community structure in the vadose and oscillated zones of RI column from those of QS and NF columns. This study suggests that RI induced rapid short-term cyclic groundwater-level oscillations could significantly influence both soil carbon cycle and bacterial community structure in vadose and oscillated zones

pH-Dependent Adsorption of Peptides on Montmorillonite for Resisting UV Irradiation

Ultraviolet (UV) irradiation is considered an energy source for the prebiotic chemical synthesis of life’s building blocks. However, it also results in photodegradation of biology-related organic compounds on early Earth. Thus, it is important to find a process to protect these compounds from decomposition by UV irradiation. Herein, pH effects on both the adsorption of peptides on montmorillonite (MMT) and the abilities of peptides to resist UV irradiation due to this adsorption were systematically studied. We found that montmorillonite (MMT) can adsorb peptides effectively under acidic conditions, while MMT-adsorbed peptides can be released under basic conditions. Peptide adsorption is positively correlated with the length of the peptide chains. MMT’s adsorption of peptides and MMT-adsorbed peptide desorption are both rapid-equilibrium, and it takes less than 30 min to reach the equilibrium in both cases. Furthermore, compared to free peptides, MMT-adsorbed peptides under acidic conditions are well protected from UV degradation even after prolonged irradiation. These results indicate amino acid/peptides are able to concentrate from aqueous solution by MMT adsorption under low-pH conditions (concentration step). The MMT-adsorbed peptides survive under UV irradiation among other unprotected species (storage step). Then, the MMT-adsorbed peptides can be released to the aqueous solution if the environment becomes more basic (releasing step), and these free peptides are ready for polymerization to polypeptides. Hence, a plausible prebiotic concentration–storage–release cycle of amino acids/peptides for further polypeptide synthesis is established

Reliability Assessment of Power Systems with Photovoltaic Power Stations Based on Intelligent State Space Reduction and Pseudo-Sequential Monte Carlo Simulation

As the number and capacity of photovoltaic (PV) power stations increase, it is of great significance to evaluate the PV-connected power systems in an effective, reasonable, and quick way. In order to overcome the challenge of PV’s time-sequential characteristic and improve upon the computational efficiency, this paper presents a new methodology to evaluate the reliability of the power system with photovoltaic power stations, which combines intelligent state space reduction and a pseudo-sequential Monte Carlo simulation (PMCS). First, a non-aggregate Markov model of photovoltaic output is established, which effectively retains some time-sequential representation of the PV output. Then, the differential evolution algorithm (DE) is introduced into the sampling stage of PMCS to carry out an intelligent state space reduction (ISSR). By using the DE algorithm, success states are searched out and removed, thus the state space is reduced and formed with a high density of loss-of-load. Hence, unnecessary samplings are avoided, which optimizes the PMCS sampling mechanism and improves the computational efficiency. Finally, the proposed method is tested in the modified IEEE RTS-79 system. The results indicate that this new method has a better computational efficiency than the time-sequential Monte Carlo simulation method (TMCS) and pure PMCS. In addition, the effectiveness and feasibility of this method are also verified

Cross-Language End-to-End Speech Recognition Research Based on Transfer Learning for the Low-Resource Tujia Language

To rescue and preserve an endangered language, this paper studied an end-to-end speech recognition model based on sample transfer learning for the low-resource Tujia language. From the perspective of the Tujia language international phonetic alphabet (IPA) label layer, using Chinese corpus as an extension of the Tujia language can effectively solve the problem of an insufficient corpus in the Tujia language, constructing a cross-language corpus and an IPA dictionary that is unified between the Chinese and Tujia languages. The convolutional neural network (CNN) and bi-directional long short-term memory (BiLSTM) network were used to extract the cross-language acoustic features and train shared hidden layer weights for the Tujia language and Chinese phonetic corpus. In addition, the automatic speech recognition function of the Tujia language was realized using the end-to-end method that consists of symmetric encoding and decoding. Furthermore, transfer learning was used to establish the model of the cross-language end-to-end Tujia language recognition system. The experimental results showed that the recognition error rate of the proposed model is 46.19%, which is 2.11% lower than the that of the model that only used the Tujia language data for training. Therefore, this approach is feasible and effective

Additional file 1 of Association between living arrangements and cognitive decline in older adults: A nationally representative longitudinal study in China

Supplementary Material 1. Supplemental Methods. 1) Demographic characteristics. 2) Health status. 3) Child characteristics. 4) Socioeconomic level. Supplementary tables. Table S1. The questionnaire items of CESD-10 and its answer options and marks assigned. Table S2. Baseline characteristics between participants included and not included. Table S3 Sensitivity analysis of the association between living arrangements and cognitive decline. Table S4 Sensitivity analysis of gender differences in the association between living arrangements and cognitive decline

Overexpression of Ubiquitin-Specific Protease 2 (USP2) in the Heart Suppressed Pressure Overload-Induced Cardiac Remodeling

Ubiquitin-specific protease 2 (USP2) is an important member of the deubiquitination system. GEO dataset revealed that USP2 was downregulated in the hearts under pressure overload. However, the cardiomyocyte-specific function of USP2 in the setting of pressure overload is unknown. In the current study, a mouse model of pressure overload was induced by transverse aortic constriction (TAC, 2 weeks). Overexpression of USP2 in the heart was conducted by AAV9 infection. Changes in heart histology were detected by Masson’s trichrome staining and hematoxylin-eosin staining (H&E). Echocardiography was used to assess cardiac function. The size of cardiomyocytes was examined by wheat germ agglutinin (WGA) staining. Cardiac oxidative stress was detected by dihydroethidine staining. Our results showed that USP2 was downregulated in the cardiomyocytes following 2 weeks of TAC. Overexpression of cardiac USP2 preserved ventricular function following 2 weeks of TAC. Overexpression of cardiac USP2 inhibited TAC-induced cardiac remodeling, by suppressing cardiac hypertrophy, inhibiting inflammatory responses and fibrosis, and attenuating oxidative stress. Our findings reveal a previously unrecognized role of USP2 in regulating pressure overload-induced cardiac remodeling

Application and reactivation of magnetic nanoparticles in Microcystis aeruginosa harvesting

This study developed a magnetic nanoparticles (MNPs) harvesting and reactivation technique for rapid cyanobacteria Microcystis aeruginosa separation. The harvesting of raw MNPs achieved high efficiency of 99.6% with the MNPs dosage of 0.58g MNPs/g dry-biomass, but gradually decreased to 59.1% when directly reused 5 times. With extra ultrasonic chloroform:methanol solvent treatment, the MNPs can be effectively reactivated for M. aeruginosa harvesting with 60% efficiency after 5 times reactivation and the separation efficiency kept above 93% with 0.20g MNPs/g dry-biomass dosage. The cyanobacteria-MNPs complex can be effectively disrupted by ultrasonic chloroform:methanol solvent treatment and the zeta potential was recovered for MNPs electrostatic attraction. The MNPs adsorption followed the Langmuir isotherm, and the maximum adsorption capacity and Langmuir constant was 3.74g dry-biomass/g and 311.64L/g respectively. This MNPs reactivation technique can achieve low energy separation and reduce MNPs consumption by 67%, providing potential engineering implementation for cyanobacterial biomass harvesting

Natural gas accumulation and models in Ordovician carbonates, Ordos Basin, NW China

According to sedimentary environment, sources, hydrocarbon accumulation characteristics and gas reservoir types of the Ordovician in the Ordos Basin, the Ordovician carbonate rocks in the basin have good gas accumulation conditions. A large number of geological and geochemical evidence shows a triple source supply. In addition to the Upper Carboniferous – Permian coal measures hydrocarbon source rocks as the main hydrocarbon source rocks, the Middle-Upper Ordovician marine hydrocarbon source rocks and Carboniferous Benxi marlstones have certain ability for hydrocarbon. Analysis of the known gas reservoir reveals that the gas in the gas fields of the central basin belongs to thermal cracking gas which is a mixed gas of coal-derived gas and crude oil cracking gas. Coal-derived gas comes from the coal measures hydrocarbon source rocks of the Carboniferous-Permian undoubtedly. Crude oil cracking gas mainly comes from the high temperature cracking gas in the Jurassic reservoir. Asphalts and hydrocarbon inclusions in the Ordovician reservoirs evidence that the oil of the Jurassic paleo-oil reservoir is mainly from the Middle-Upper Ordovician marine hydrocarbon source rocks. Gas accumulation has evolved from oil reservoir to gas reservoir: oil pool formed in the Jurassic and the oil cracked into gas in the Cretaceous. Controlled by tectonic sedimentary setting, four accumulation models of carbonate gas reservoir have been structured. Among them, weathering crust lithostratigraphic gas reservoir in the central part of the basin and composite lithology gas reservoir of structure – bedding karst type in the northwest platform marginal zone are the focus of the carbonate gas exploration. Key words: Ordos Basin, Ordovician, carbonate, hydrocarbon source rock, accumulation characteristics, accumulation evolution, gas reservoir mode