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Graphitic electrode is commonly used in electrochemical reactions owing to its excellent in-plane conductivity, structural robustness and cost efficiency 1 , 2 . It serves as prime electrocatalyst support as well as a layered intercalation matrix 2 , 3 , with wide applications in energy conversion and storage 1 , 4 . Being the two-dimensional building block of graphite, graphene shares similar chemical properties with graphite 1 , 2 , and its unique physical and chemical properties offer more varieties and tunability for developing state-of-the-art graphitic devices 5 – 7 . Hence it serves as an ideal platform to investigate the microscopic structure and reaction kinetics at the graphitic-electrode interfaces. Unfortunately, graphene is susceptible to various extrinsic factors, such as substrate effect 8 – 10 , causing much confusion and controversy 7 , 8 , 10 , 11 . Hereby we have obtained centimetre-sized substrate-free monolayer graphene suspended on aqueous electrolyte surface with gate tunability. Using sum-frequency spectroscopy, here we show the structural evolution versus the gate voltage at the graphene–water interface. The hydrogen-bond network of water in the Stern layer is barely changed within the water-electrolysis window but undergoes notable change when switching on the electrochemical reactions. The dangling O–H bond protruding at the graphene–water interface disappears at the onset of the hydrogen evolution reaction, signifying a marked structural change on the topmost layer owing to excess intermediate species next to the electrode. The large-size suspended pristine graphene offers a new platform to unravel the microscopic processes at the graphitic-electrode interfaces. Using centimetre-sized substrate-free monolayer graphene suspended on aqueous electrolyte surface, the structural evolution versus gate voltage at the graphene–water interface is shown, demonstrating minimal influence of extrinsic factors.

Graphene serves as an ideal platform to investigate the microscopic structure and reaction kinetics at the graphitic electrode interfaces. However, graphene is susceptible to various extrinsic factors, e.g. substrate, causing much confusion and controversy. Hereby we have obtained cm-sized substrate-free monolayer graphene suspended on electrolyte surface with gate tunability. Using sum-frequency spectroscopy, we have observed the structural evolution versus the gate voltage at the graphene/water interface. The Stern layer structure is invariant within the water electrolysis window, but undergoes drastic change when switching on the electrochemical reactions. The electrode is turned from hydrophobic to hydrophilic near the onset of hydrogen evolution reaction due to hydrogen adsorption. The large-size suspended pristine graphene offers a new platform to unravel the microscopic processes at the graphitic electrode interfaces.

Previous animal studies of cauda equina injury have primarily used rat models, which display significant differences from humans. Furthermore, most studies have focused on electrophysio- logical examination. To better mimic the outcome after surgical repair of cauda equina injury, a novel animal model was established in the goat. Electrophysiological, histological and magnetic resonance imaging methods were used to evaluate the morphological and functional outcome after cauda equina injury and end-to-end suture. Our results demonstrate successful establish- ment of the goat experimental model of cauda equina injury. This novel model can provide detailed information on the nerve regenerative process following surgical repair of cauda equina injury.

Outdoor autonomous mobile robots heavily rely on GPS data for localization. However, GPS data can be erroneous and signals can be interrupted in highly urbanized areas or areas with incomplete satellite coverage, leading to localization deviations. In this paper, we propose a SLAM (Simultaneous Localization and Mapping) system that combines the IESKF (Iterated Extended Kalman Filter) and a factor graph to address these issues. We perform IESKF filtering on LiDAR and inertial measurement unit (IMU) data at the front-end to achieve a more accurate estimation of local pose and incorporate the resulting laser inertial odometry into the back-end factor graph. Furthermore, we introduce a GPS signal filtering method based on GPS state and confidence to ensure that abnormal GPS data is not used in the back-end processing. In the back-end factor graph, we incorporate loop closure factors, IMU preintegration factors, and processed GPS factors. We conducted comparative experiments using the publicly available KITTI dataset and our own experimental platform to compare the proposed SLAM system with two commonly used SLAM systems: the filter-based SLAM system (FAST-LIO) and the graph optimization-based SLAM system (LIO-SAM). The experimental results demonstrate that the proposed SLAM system outperforms the other systems in terms of localization accuracy, especially in cases of GPS signal interruption.

Increasing evidence indicates a role of leptin in immune response, but it remains largely unclear whether leptin signaling is involved in regulating NK cell development in the bone marrow （BM）. In this study, we have characterized NK cell differentiation and maturation in the BM of leptin-receptor deficient db/db mice at a prediabetic stage. Although the BM cellularity was similar to the control value, the total number of NK cells was severely reduced in mutant mice. Flow cytometric analysis of db/db BM cells revealed significantly decreased frequencies of developing NK cells at various stages of differentiation. BM db/db NK cells displayed markedly increased apoptosis but maintained normal cell cycling status and proliferative capacity. Moreover, recombinant leptin could significantly enhance the survival of NK cells from wild-type mice in cultures. Further examination on NK cell functional activity showed that db/db NK cells exhibited normal intrinsic cytotoxicity with significantly increased IL-10 production. Taken together, our findings suggest that leptin signaling regulates NK cell development via enhancing the survival of immature NK cells in mouse BM.

Precision positioning systems driven by linear motors are vulnerable to force disturbances owing to the reduction of gear transmission. The friction, included in the disturbance, can be modeled and compensated to improve the servo performance. This paper proposes a modified Stribeck friction model (SFM) and an optimization algorithm for consistency with the positioning platform. The compensators based on the friction model and disturbance observer (DOB) are simulated. The simulation results show that as compared with the DOB compensator (the velocity recovers by 5.19%), the friction model based compensator (the velocity recovers by 10.66%) exhibits a better performance after adding the disturbance. Moreover, compensation comparisons among the Coulomb friction, traditional SFM, and modified SFM are performed. The experimental results show that the following error with modified SFM compensation improves by 67.67% and 51.63% at a speed of 0.005 m/s and 0.05 m/s, compared with the Coulomb friction compensation. This demonstrates that the proposed model, optimization algorithm, and compensator can reduce the following error effectively.

A high-performance liquid chromatography–electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was successfully developed and validated for the identification and determination of eight ginsenosides: ginsenoside Rg1 (1); 20(S)-ginsenoside Rh1 (2); 20(S)-ginsenoside Rg2 (3); 20(R)-ginsenoside Rh1 (4); 20(R)-ginsenoside Rg2 (5); ginsenoside Rd (6); 20(S)-ginsenoside Rg3 (7); and 20(R)-ginsenoside Rg3 (8) in rat plasma. The established rapid method had high linearity, selectivity, sensitivity, accuracy, and precision. The method has been used successfully to study the pharmacokinetics of abovementioned eight ginsenosides for the first time. After an oral administration of total saponins in the stems-leaves of Panax ginseng C. A. Meyer (GTSSL) at a dose of 400 mg/kg, the ginsenosides 6, 7, and 8, belonging to protopanaxadiol-type saponins, exhibited relatively long tmax values, suggesting that they were slowly absorbed, while the ginsenosides 1–5, belonging to protopanaxatriol-type saponins, had different tmax values, which should be due to their differences in the substituted groups. Compounds 2 and 4, 3 and 5, 7 and 8 were three pairs of R/S epimerics at C-20, which was interesting that the t1/2 of 20(S)-epimers were always longer than those of 20(R)-epimers. This pharmacokinetic identification of multiple ginsenosides of GTSSL in rat plasma provides a significant basis for better understanding the clinical application of GTSSL.

We will first prove the existence of (V,V)- and (V,H2)-absorbing sets for the three-dimensional primitive equations of large-scale atmosphere in log-pressure coordinate and then prove the existence of (V,H3)-absorbing set by the use of the elliptic regularity theory. Finally, we obtain the existence of (V,V)- and (V,H2)-global attractors for the three-dimensional viscous primitive equations of large-scale atmosphere in log-pressure coordinate by using the Sobolev compactness embedding theory.

Background: The widespread threat of severe acute respiratory syndrome (SARS) to human life has spawned challenges to develop fast and accurate analytical methods for its early diagnosis and to create a safe antiviral vaccine for preventive use. Consequently, we thoroughly investigated the immunoreactivities with patient sera of a series of synthesized peptides from SARS-coronavirus structural proteins. Methods: We synthesized 41 peptides ranging in size from 16 to 25 amino acid residues of relatively high hydrophilicity. The immunoreactivities of the peptides with SARS patient sera were determined by ELISA. Results: Four epitopic sites, S599, M137, N66, and N371-404, located in the SARS-coronavirus S, M, and N proteins, respectively, were detected by screening synthesized peptides. Notably, N371 and N385, located at the COOH terminus of the N protein, inhibited binding of antibodies to SARS-coronavirus lysate and bound to antibodies in >94% of samples from SARS study patients. N385 had the highest affinity for forming peptide-antibody complexes with SARS serum. Conclusions: Five peptides from SARS structural proteins, especially two from the COOH terminus of the N protein, appear to be highly immunogenic and may be useful for serologic assays. The identification of these antigenic peptides contributes to the understanding of the immunogenicity and persistence of SARS coronavirus.

Abundant neutral seawater is a potential alternative to high-purity freshwater for green hydrogen generation, while direct seawater electrolysis catalyzed by transition metals-based materials faces severe corrosion issues due to the chlorine evolution reaction (ClER) which would pose secondary heavy metal pollution, and sluggish kinetics of oxygen evolution reaction (OER). Herein, we report that the robust metal-free pyridinic nitrogen-rich carbon paper (N-CP-800) can effectively catalyze the hydrazine oxidation reaction (HzOR) to replace OER in neutral simulated seawater for energy-saving hydrogen production. Combined with electrochemical experiments, operando electrochemical attenuated total reflection surface-enhanced Fourier transform infrared spectroscopy characterizations, and density functional theory calculations reveal that the pyridinic nitrogen with both zig and arm configurations favor the rate-limiting proton desorption of the (*H + N 2 H 1 ) intermediates relative to pyrrolic and graphitic nitrogen for improved HzOR. Consequently, the resulting N-CP-800 enriched with pyridinic nitrogen requires a potential of only 0.78 V vs. reversible hydrogen electrode at 10 mA cm −2 for HzOR in neutral media, lower than those for the competitive OER/ClER. When coupling N-CP-800 with a nonprecious hydrogen evolution catalyst of CoP, a low voltage of 1.56 V at 10 mA cm −2 is needed to perform the HzOR-assisted seawater electrolysis with long-term stability for 200 h, superior to those of Pt/C and RuO 2 benchmark in seawater directly.