Ferrihydrite-mediated methanotrophic nitrogen fixation in paddy soil under hypoxia.

Biological nitrogen fixation (BNF) by methanotrophic bacteria has been shown to play an important role in maintaining fertility. However, this process is still limited to aerobic methane oxidation with sufficient oxygen. It has remained unknown whether and how methanotrophic BNF proceeds in hypoxic environments.

Wavelength-tunable spatiotemporal mode-locking in a large-mode-area Er:ZBLAN fiber laser at 2.8 µm.

We report a tunable spatiotemporally mode-locked large-mode-area Er:ZBLAN fiber laser based on the nonlinear polarization rotation technique. A diffraction grating is introduced to select the operating wavelength. Under the spectral and spatial filtering effects provided by the grating and spatial coupling respectively, stable ps-level spatiotemporally mode-locked pulses around 2.

Fiber Characteristics and Mechanical Properties of .

Unlike the culm hollow structure of most bamboo species, has a unique solid or semi-solid culm, which may endow it with superior mechanical performance. In this study, the variation in fiber morphology and micro-mechanical properties across the radial regions of bamboo culm was examined by optical microscopy, scanning electron microscopy, X-ray diffraction, and nanoindentation. Results showed that the mean values of vascular bundle frequency and fiber tissue proportion were 1.

High-energy femtosecond pulse generation from a hybrid mode-locked large-mode-area Er:ZBLAN fiber laser.

We report a hybrid mode-locked fiber laser at 2.8 µm based on a large-mode-area Er:ZBLAN fiber. Reliable self-starting mode-locking is achieved via the combination of nonlinear polarization rotation and a semiconductor saturable absorber.

All-fiber 3.4-W 2.8-µm ultra-short pulse MOPA system seeded by the soliton self-frequency shift of 2-µm pulses.

We report an all-fiber 2.8-µm ultra-short pulse master oscillator power amplifier (MOPA) system seeded by a soliton self-frequency shift from a mode-locked thulium-doped fiber laser. This all-fiber laser source delivers 2.

976 nm all-polarization-maintaining mode-locked fiber laser based on nonlinear polarization evolution.

An all-polarization-maintaining (PM) mode-locked fiber laser based upon nonlinear polarization evolution (NPE) that operates around 976 nm is presented. The NPE-based mode-locking is realized using a special section of the laser which comprises three pieces of PM fibers with specific deviation angles between the polarization axes and a polarization-dependent isolator. By optimizing the NPE section and adjusting the pump power, dissipative soliton (DS) pulses with a pulse duration of ∼6 ps, a spectral bandwidth of >10 nm and a maximum pulse energy of 0.

Combining biological denitrification and electricity generation in methane-powered microbial fuel cells.

Methane has been demonstrated to be a feasible substrate for electricity generation in microbial fuel cells (MFCs) and denitrifying anaerobic methane oxidation (DAMO). However, these two processes were evaluated separately in previous studies and it has remained unknown whether methane is able to simultaneously drive these processes. Here we investigated the co-occurrence and performance of these two processes in the anodic chamber of MFCs.

Mid-infrared ultrashort pulses generated from a hybrid mode-locked Er:ZBLAN fiber laser.

By combining nonlinear polarization rotation (NPR) and semiconductor saturable absorber, we report a hybrid mode-locked Er:ZBLAN fiber oscillator at 2.8 µm. Stable 325-fs mode-locked pulses with an average power of 131 mW and a record signal-to-noise ratio of 79 dB at the fundamental frequency of 55.

Tunable mode-locked Tm-doped fiber laser based upon cross-phase modulation.

We demonstrate the generation of soliton and dissipative soliton in an ultrafast thulium (Tm) doped fiber laser based upon cross-phase modulation (XPM) induced mode-locking. The mode-locking is realized by periodically modulating the 2-µm signal through XPM that is activated by an injected 1.5-µm pulsed laser.

Anaerobic methane oxidation coupled to ferrihydrite reduction by Methanosarcina barkeri.

Fe(III) has been recognized as a potential electron sink for the anaerobic oxidation of methane (Fe-AOM) in diverse environments. However, most of previous Fe-AOM processes are limited to ANME archaea and the Fe-AOM mechanism remains unclear. Here we investigate, for the first time, the Fe-AOM performance and mechanisms by a single methanogen Methanosarcina barkeri.

Average-power (4.13 W) 59 fs mid-infrared pulses from a fluoride fiber laser system.

We report a high-average-power mid-infrared ultrafast laser system consisting of a fluoride fiber mode-locked oscillator and a nonlinear amplifier. A backward pumping scheme was used in the amplifier to simultaneously realize pulse amplification and self-compression. The input signal polarization was demonstrated to play an important role in the self-compression process.

High Modulation Depth Enabled by MoTiCT MXene for Q-Switched Pulse Generation in a Mid-Infrared Fiber Laser.

Two-dimensional (2D) materials show great promise as saturable absorbers (SAs) for ultrafast fiber lasers. However, the relatively low modulation depth and poor stability of some 2D materials, such as graphene and black phosphorus, restrict their applications in the mid-infrared pulse generation. Herein, we first report a novel 2D double transition metal carbide, denoted as MoTiCT MXene, as the saturable absorber (SA) for a passively Q-switched mid-infrared fiber laser.

Acetate and electricity generation from methane in conductive fiber membrane- microbial fuel cells.

Microbial conversion of methane to electricity, fuels, and liquid chemicals has attracted much attention. However, due to the low solubility of methane, it is not considered a suitable substrate for microbial fuel cells (MFCs). In this study, a conductive fiber membrane (CFM) module was constructed as the bioanode of methane-driven MFCs, directly delivering methane.

Biochar enhances bioelectrochemical remediation of pentachlorophenol-contaminated soils via long-distance electron transfer.

The soil bioelectrochemical system (SBES) is a promising biotechnology for the remediation of contaminated soils. However, the effective distance of pollutant removal in the SBES was usually limited in a few centimeters near the electrode surface. In this study, we used biochar as the model conductor to construct a conductive network with microbes in the soil matrix to extend the effective distance of pollutant removal in the SBES.

Electron shuttles enhance anaerobic oxidation of methane coupled to iron(III) reduction.

Anaerobic oxidation of methane (AOM) has recently been coupled with the reduction of insoluble electron acceptors such as iron minerals. However, effects of electron shuttles (ESs) on this process and the underlying coupling mechanisms remain not well understood. Here, we evaluated AOM-coupled ferrihydrite reduction by a mixed culture in the absence and presence of ESs.

Investigation of the temporal contrast evolution in a 10-PW-level Ti:sapphire laser facility.

We have theoretically and experimentally investigated the evolution of the temporal contrast in a 10-PW-level Ti:sapphire laser in the Shanghai Superintense Ultrafast Laser Facility (SULF). The effects induced by the grism pair, spectral shaping filter, and increase in gain on the temporal contrast were investigated. First, it was found that the energy loss of clean seed pulses in the grism pair is a major factor in contrast degradation.

NanoFeO as Solid Electron Shuttles to Accelerate Acetotrophic Methanogenesis by .

Magnetite nanoparticles (nanoFeO) have been reported to facilitate direct interspecies electron transfer (DIET) between syntrophic bacteria and methanogens thereby improving syntrophic methanogenesis. However, whether or how nanoFeO affects acetotrophic methanogenesis remain unknown. Herein, we demonstrate the unique role of nanoFeO in accelerating methane production from direct acetotrophic methanogenesis in -enriched cultures, which was further confirmed by pure cultures of Compared with other nanomaterials of higher electrical conductivity such as carbon nanotubes and graphite, nanoFeO with mixed valence Fe(II) and Fe(III) had the most significant stimulatory effect on methane production, suggesting its redox activity rather than electrical conductivity led to enhanced methanogenesis by .

Electric field induces electron flow to simultaneously enhance the maturity of aerobic composting and mitigate greenhouse gas emissions.

The long maturation period and greenhouse gas (GHG) emission are two major problems that arise during aerobic composting, mainly due to the low efficiency of O transmission and utilization. In this study, a novel electric-field-assisted aerobic composting (EAC) process was tested by simply applying a direct-current voltage of 2 V to a conventional aerobic composting (CAC) process. Compared with the CAC process, the maturation time and the total GHG for the EAC process were reduced by 33% and 70%, respectively.

Electrodes Donate Electrons for Nitrate Reduction in a Soil Matrix via DNRA and Denitrification.

Microbial strains and indigenous microbiota in soil slurries have been reported to use electrons from electrodes for nitrate (NO) reduction. However, few studies have confirmed this in a soil matrix hitherto. This study investigated if, and how, an electric potential affected NO reduction in a soil matrix.

Electrochemical evidence for direct interspecies electron transfer between Geobacter sulfurreducens and Prosthecochloris aestuarii.

The syntrophic photosynthesis via direct interspecies electron transfer (DIET) between Geobacter sulfurreducens and Prosthecochloris aestuarii has opened a new paradigm of microbial phototrophy. However, it is still unknown whether this photosynthetic DIET can be mediated by an electrical conductor. Here we report first the photosynthetic DIET in a two-chamber microbial fuel cell (photo-MFC).

Novel Gas Diffusion Cloth Bioanodes for High-Performance Methane-Powered Microbial Fuel Cells.

Microbial fuel cells (MFCs) are a promising technology that converts chemical energy into electricity. However, up to now only few MFCs have been powered by gas fuels, such as methane, and their limited performance is still challenged by the low solubility and bioavailability of gases. Here, we developed a gas diffusion cloth (GDC) anode to significantly enhance the performance of methane-powered MFCs.

Combined spectroelectrochemical and proteomic characterizations of bidirectional Alcaligenes faecalis-electrode electron transfer.

Bioelectrochemical systems use microbes as catalysts for current production or consumption. Up to now only a few microbes have been demonstrated to be capable of both outward and inward extracellular electron transfer (EET) (i.e.

High-contrast front end based on cascaded XPWG and femtosecond OPA for 10-PW-level Ti:sapphire laser.

By combining cross-polarized wave generation and femtosecond optical parametric amplification, a high-contrast front end featuring ultrahigh contrast, a broadband spectrum, an excellent beam profile, and good stability is built for a 10-PW-level Ti:sapphire laser in the Shanghai Superintense Ultrafast Laser Facility (SULF-10PW laser). The front end can deliver a cleaned pulse with a 110 μJ energy at 1 kHz, and the bandwidth of the cleaned pulse exceeds 60 nm (FWHM), which can support a 17 fs compressed pulse duration. The measured output energy fluctuation in one hour is <1.

Thermophilic Moorella thermoautotrophica-immobilized cathode enhanced microbial electrosynthesis of acetate and formate from CO.

Microbial electrosynthesis (MES) is a promising technique that converts electricity and CO to biofuels using microbes as the catalysts. However, most of previous MES are conducted at mesophilic temperatures and challenged by low performances. Here we report a significant electrosynthesis performance enhancement via immobilization of a thermophilic microbe to cathodes.

Biochar as an electron shuttle for reductive dechlorination of pentachlorophenol by Geobacter sulfurreducens.

The reductive dechlorination of pentachlorophenol (PCP) by Geobacter sulfurreducens in the presence of different biochars was investigated to understand how biochars affect the bioreduction of environmental contaminants. The results indicated that biochars significantly accelerate electron transfer from cells to PCP, thus enhancing reductive dechlorination. The promotion effects of biochar (as high as 24-fold) in this process depend on its electron exchange capacity (EEC) and electrical conductivity (EC).