Response of Bacterial Metabolic Activity to the River Discharge in the Pearl River Estuary: Implication for CO2 Degassing Fluxes

Bacterial production (BP), respiration (BR) and growth efficiency (BGE) were simultaneously determined along an environmental gradient in the Pearl River Estuary (PRE) in the wet season (May 2015) and the dry season (January 2016), in order to examine bacterial responses to the riverine dissolved organic carbon (DOC) in the PRE. The Pearl River discharge delivered labile dissolved organic matters (DOM) with low DOC:DON ratio, resulting in a clear gradient in DOC concentrations and DOC:DON ratios. BP (3.93–144 μg C L−1 d−1) was more variable than BR (64.6–567 μg C L−1 d−1) in terms of the percentage, along an environmental gradient in the PRE. In response to riverine DOC input, BP and the cell-specific BP increased; in contrast, the cell-specific bacterial respiration declined, likely because labile riverine DOC mitigated energetic cost for cell maintenance. Consequently, an increase in bacterial respiration was less than expected. Our findings implied that the input of highly bioavailable riverine DOC altered the carbon portioning between anabolic and catabolic pathways, consequently decreasing the fraction of DOC that bacterioplankton utilized for bacterial respiration. This might be one of the underlying mechanisms for the low CO2 degassing in the PRE receiving large amounts of sewage DOC

PyPose v0.6: The Imperative Programming Interface for Robotics

PyPose is an open-source library for robot learning. It combines a learning-based approach with physics-based optimization, which enables seamless end-to-end robot learning. It has been used in many tasks due to its meticulously designed application programming interface (API) and efficient implementation. From its initial launch in early 2022, PyPose has experienced significant enhancements, incorporating a wide variety of new features into its platform. To satisfy the growing demand for understanding and utilizing the library and reduce the learning curve of new users, we present the fundamental design principle of the imperative programming interface, and showcase the flexible usage of diverse functionalities and modules using an extremely simple Dubins car example. We also demonstrate that the PyPose can be easily used to navigate a real quadruped robot with a few lines of code

Application of Teager–Kaiser Energy Operator in the Early Fault Diagnosis of Rolling Bearings

Rolling bearings are key components that support the rotation of motor shafts, operating with a quite high failure rate among all the motor components. Early bearing fault diagnosis has great significance to the operation security of motors. The main contribution of this paper is to illustrate Gaussian white noise in bearing vibration signals seriously masks the weak fault characteristics in the diagnosis based on the Teager–Kaiser energy operator envelope, and to propose improved TKEO taking both accuracy and calculation speed into account. Improved TKEO can attenuate noise in consideration of computational efficiency while preserving information about the possible fault. The proposed method can be characterized as follows: a series of band-pass filters were set up to extract several component signals from the original vibration signals; then a denoised target signal including fault information was reconstructed by weighted summation of these component signals; finally, the Fourier spectrum of TKEO energy of the resulting target signal was used for bearing fault diagnosis. The improved TKEO was applied to a vibration signal dataset of run-to-failure rolling bearings and compared with two advanced diagnosis methods. The experimental results verify the effectiveness and superiority of the proposed method in early bearing fault detection

Bacterial Carbon Cycling in the River Plume in the Northern South China Sea During Summer

Heterotrophic bacterioplankton play a significant role in carbon cycle in oceans. It is crucial to identify regulators of bacterial carbon processing across marine environments. In summer 2016, a cruise was conducted to examine the links between bacterial metabolic rates and community composition, and potential mechanisms regulating bacterial growth efficiency in the plume-impacted coastal area. Our results showed that the two aspects of bacterial metabolism responded differently. Bacterial production (3.69 to 57.1gC L -1 day( -1)) at the surface increased by 40% to 21-fold in response to the freshwater input. The enhanced bacterial production was attributed to an increase in bacterial abundance and cell-specific bacterial production, which was linked to shifts in bacterial community composition and changing partition between anabolic and catabolic pathways. Bacterial groups that grew fast and preferred high molecular weight dissolved organic carbon were responsible for the increase in bacterial production. However, bacterial respiration increased (less than fourfold) to lesser extent than bacterial production. Consequently, bacterial growth efficiency increased dramatically (up to sevenfold) in response to the plume input. Bacterial respiration was primarily dependent on environmental conditions rather than bacterial community composition. The increased phytoplankton biomass modulated bacterial respiration in two contrasting ways likely by providing phytoplankton-derived dissolved organic carbon, which not only improved bacterial abundance but also lowered cell-specific bacterial respiration because of mitigating energy limitation. Our findings elucidated bacterial carbon processing in the plume-impacted coastal waters and highlighted the potential role of bacterial community composition in regulating carbon cycling in oceans. Plain Language Summary Heterotrophic bacterioplankton play a significant role in carbon cycle in oceans. The two aspects of bacterial metabolism responded differently to the river plume. Bacterial production increased by 40% to 21-fold, in response to the river plume. The enhanced bacterial production was attributed to an increase in bacterial abundance and cell-specific bacterial production, which was linked to shifts in bacterial community composition and changing partition between anabolic and catabolic pathways. Bacterial group that grew fast and preferred high molecular weight dissolved organic carbon (DOC) was responsible for the increase in bacterial production. However, bacterial respiration increased (less than fourfold) to lesser extent than bacterial production. Consequently, bacterial growth efficiency increased dramatically (up to sevenfold) in response to the plume input. Bacterial respiration was primarily dependent on environmental conditions rather than shifts in bacterial community composition. The increased phytoplankton biomass modulated bacterial respiration in two contrasting ways likely by providing phytoplankton-derived DOC, which not only improved bacterial abundance but also lowered cell-specific bacterial respiration because of mitigating energy limitation. Our findings elucidated bacterial carbon processing in the plume-impacted coastal waters and highlighted the potential role of bacterial community composition in regulating carbon cycling in oceans

Zigzag boron nitride nanoribbon doped with carbon atom for giant magnetoresistance and rectification behavior based nanodevices

Abstract Using the principles of density functional theory (DFT) and nonequilibrium Green’s function (NEGF), We thoroughly researched carbon-doped zigzag boron nitride nanoribbons (ZBNNRs) to understand their electronic behavior and transport properties. Intriguingly, we discovered that careful doping can transform carbon-doped ZBNNRs into a spintronic nanodevice with distinct transport features. Our model showed a giant magnetoresistance (GMR) up to a whopping 10 $$^5$$ 5 under mild bias conditions. Plus, we spotted a spin rectifier having a significant rectification ratio (RR) of 10 $$^4$$ 4 . Our calculated transmission spectra have nicely explained why there’s a GMR up to 10 $$^5$$ 5 for spin-up current at biases of $$-1.2$$ - 1.2 V, $$-1.1$$ - 1.1 V, and $$-1.0$$ - 1.0 V, and also accounted for a GMR up to 10 $$^3$$ 3 –10 $$^5$$ 5 for spin-down current at biases of 1.0 V, 1.1 V, and 1.2 V. Similarly, the transmission spectra elucidate that at biases of 1.0 V, 1.1 V, and 1.2 V for spin-up, and at biases of 1.1 V and 1.2 V for spin-down in APMO, the RRs reach 10 $$^4$$ 4 . Our research shines a light on a promising route to push forward the high-performance spintronics technology of ZBNNRs using carbon atom doping. These insights hint that our models could be game-changers in the sphere of nanoscale spintronic devices

Paralytic shellfish toxins producing dinoflagellates cause dysbacteriosis in scallop gut microbial biofilms

Filter-feeding bivalves could accumulate paralytic shellfish toxins (PSTs) produced by harmful dinoflagellates through diet. Despite that bivalves are resistant to these neurotoxins due to possessing PST-resistant sodium channel, exposure to PSTs-producing dinoflagellates impair bivalve survival. We hypothesized that ingesting PSTs-producing dinoflagellates may influence the gut microbiota, and then the health of bivalves. To test this idea, we compared the gut microbiota of the scallop Patinopecten yessoensis, after feeding with PST-producing or non-toxic dinoflagellates. Exposure to PSTs-producing dinoflagellates resulted in a decline of gut microbial diversity and a disturbance of community structure, accompanied by a significant increase in the abundance and richness of pathogenic bacteria, represented by Vibrio. Moreover, network analysis demonstrated extensive positive correlations between pathogenic bacteria abundances and PSTs concentrations in the digestive glands of the scallops. Furthermore, isolation of a dominant Vibrio strain and its genomic analysis revealed a variety of virulence factors, including the tolC outer membrane exporter, which were expressed in the gut microbiota. Finally, the infection experiment demonstrated scallop mortality caused by the isolated Vibrio strain; further, the pathogenicity of this Vibrio strain was attenuated by a mutation in the tolC gene. Together, these findings demonstrated that the PSTs may affect gut microbiota via direct and taxa-specific interactions with opportunistic pathogens, which proliferate after transition from seawater to the gut environment. The present study has revealed novel mechanisms towards deciphering the puzzles in environmental disturbances-caused death of an important aquaculture species

Membrane curvature governs the distribution of Piezo1 in live cells

Piezo1 is a bona fide mechanosensitive ion channel ubiquitously expressed in mammalian cells. The distribution of Piezo1 within a cell is essential for various biological processes including cytokinesis, cell migration, and wound healing. However, the underlying principles that guide the subcellular distribution of Piezo1 remain largely unexplored. Here, we demonstrate that membrane curvature serves as a key regulator of the spatial distribution of Piezo1 in the plasma membrane of living cells. Piezo1 depletes from highly curved membrane protrusions such as filopodia and enriches to nanoscale membrane invaginations. Quantification of the curvature-dependent sorting of Piezo1 directly reveals the in situ nano-geometry of the Piezo1-membrane complex. Piezo1 density on filopodia increases upon activation, independent of calcium, suggesting flattening of the channel upon opening. Consequently, the expression of Piezo1 inhibits filopodia formation, an effect that diminishes with channel activation