Bimetallic Cu-Fe catalysts on MXene for synergistically electrocatalytic conversion of nitrate to ammonia.

NO3- is a common water pollutant that can serve as a potential nitrogen source for electrocatalytic NH3 production. However, an efficient and complete removal of low NO3- concentrations remains a challenge. Fe1Cu2@MXene bimetallic catalysts were constructed on two-dimensional Ti3C2Tx MXene carriers via a simple solution-based synthetic method and used for the electrocatalytic reduction of NO3-. The combination of the rich functional groups, high electronic conductivity on the MXene surface, and the synergistic effect between the Cu and Fe sites enabled the composite to effectively catalyse NH3 synthesis, with a 98% conversion of NO3- in 8 h and a selectivity for NH3 of up to 99.6%. In addition, Fe1Cu2@MXene showed excellent environmental and cyclic stability at various pH values and temperatures over multiple (14) cycles. Semiconductor analysis techniques and electrochemical impedance spectroscopy confirmed that the synergistic effect provided by the dual active sites of the bimetallic catalyst enabled fast electron transport. This study provides new insights into the synergistic promotion of NO3- reduction reactions using bimetals.

Self-supported spinel nanosphere as bifunctional electrocatalysts for energy-saving hydrogen production via urea-water electrolysis.

Electrochemical oxidation of urea is of great importance in the removal and energy exchange and storage of urea from wastewater as well as of potential applications in potable dialysis of end-stage renal disease. However, the lack of economical electrocatalysts hinders its widespread application. In this study, we successfully fabricated ZnCo2O4 nanospheres with bifunctional catalysis on nickel foam (NF). The catalytic system has high catalytic activity and durability for urea overall electrolysis. The urea oxidation and hydrogen evolution reactions required only 1.32 V and -80.91 mV to obtain ± 10 mA cm-2. Only 1.39 V was needed to obtain 10 mA cm-2 for 40 h without noticeably declining activity. The excellent performance could be attributed to the fact that the material can provide multiple redox couplings and a three-dimensional porous structure to facilitate the release of gases from the surface.

Nacre-Inspired Bacterial Cellulose/Mica Nanopaper with Excellent Mechanical and Electrical Insulating Properties by Biosynthesis.

The exploration of extreme environments has become necessary for understanding and changing nature. However, the development of functional materials suitable for extreme conditions is still insufficient. Herein, a kind of nacre-inspired bacterial cellulose (BC)/synthetic mica (S-Mica) nanopaper with excellent mechanical and electrical insulating properties that has excellent tolerance to extreme conditions is reported. Benefited from the nacre-inspired structure and the 3D network of BC, the nanopaper exhibits excellent mechanical properties, including high tensile strength (375 MPa), outstanding foldability, and bending fatigue resistance. In addition, S-Mica arranged in layers endows the nanopaper with remarkable dielectric strength (145.7 kV mm-1 ) and ultralong corona resistance life. Moreover, the nanopaper is highly resistant to alternating high and low temperatures, UV light, and atomic oxygen, making it an ideal candidate for extreme environment-resistant materials.

Current practice for the treatment of obstructive left-sided colon cancer in China: a nationwide cross-sectional survey.

PURPOSE: This study surveyed the current practice of surgical treatment of obstructive left-sided colon cancer (OLCC) in China. METHODS: All colorectal surgery departments at tertiary or secondary hospitals in China were invited to complete a web-based questionnaire between August 27 and September 2, 2020. RESULTS: Overall, completed questionnaire were received from 357 hospitals. Emergency surgery was the mainstay of treatment for OLCC, with the open approach accounting for up to 61.62%. The stoma rate of emergency surgery was up to 80%, mainly due to inadequate bowel preparation and severe edema of colon walls. Hartmann's procedure (61.62%) was the most preferred operation. A total of 243 hospitals (68.7%) reported that they would consider the use of a self-expanding metallic stent (SEMS) as a bridge for elective surgery. More than 50% of the hospitals participating in this study reported the success rate of SEMS placement, as well as the resolution rate of obstruction more than 80%, and the stent-related perforation rate was < 5%. A total of 126 hospitals considered carrying out a strategy of SEMS followed by neoadjuvant chemotherapy prior to elective surgery and believed that it might further improve treatment outcomes. CONCLUSIONS: SEMS is a feasible option for the treatment of OLCC in addition to traditional emergency surgery, and its clinical benefits have been preliminarily recognized.

Coordination Symmetry Breaking of Single-Atom Catalysts for Robust and Efficient Nitrate Electroreduction to Ammonia.

Nitrate electrocatalytic reduction (NO3 RR) for ammonia production is a promising strategy to close the N-cycle from nitration contamination, as well as an alternative to the Haber-Bosch process with less energy consumption and carbon dioxide release. However, current long-term stability of NO3 RR catalysts is usually tens of hours, far from the requirements for industrialization. Here, symmetry-broken Cusingle-atom catalysts are designed, and the catalytic activity is retained after operation for more than 2000 h, while an average ammonia production rate of 27.84 mg h-1 cm-2 at an industrial level current density of 366 mA cm-2 is achieved, obtaining a good balance between catalytic activity and long-term stability. Coordination symmetry breaking is achieved by embedding one Cu atom in graphene nanosheets with two N and two O atoms in the cis-configuration, effectively lowering the coordination symmetry, rendering the active site more polar, and accumulating more NO3 - near the electrocatalyst surface. Additionally, the cis-coordination splits the Cu 3d orbitals, which generates an orbital-symmetry-matched π-complex of the key intermediate *ONH and reduces the energy barrier, compared with the σ-complex generated with other catalysts. These results reveal the critical role of coordination symmetry in single-atom catalysts, prompting the design of more coordination-symmetry-broken electrocatalysts toward possible industrialization.

[Hematoma Segmentation of Spontaneous Intracerebral Hemorrhage Based on Watershed and Region-Growing Algorithm].

Objective: To establish a brain hematoma CT image segmentation method based on watershed and region-growing algorithm so as to measure hematoma volume quickly and accurately, to explore the consistency between the results of this segmentation method and those of manual segmentation, the clinical gold standard, and to compare the results of this method with the calculation of the two Tada formulas commonly used in clinical practice. Methods: The preoperative CT images of 152 patients who were treated for spontaneous cerebral hemorrhage at the Department of Neurosurgery, West China Hospital, Sichuan University between January 2018 and June 2019 were retrospectively collected. The CT images were randomly assigned, by using a random number table, to the training set, the test set and the validation set, which contained 100 patients, 22 patients and 30 patients, respectively. The labeling results of the training set and the test set were used in algorithm training and testing. Four methods, namely, manual segmentation, algorithm segmentation, i.e., segmentation calculation based on watershed and regional growth algorithm, Tada formula, i.e., the traditional Tada formula calculation, and accurate Tada formula, i.e., accurate Tada formula calculation based on 3D-Slicer, were applied on the validation set to measure the hematoma volume. The Digital Imaging and Communications in Medicine (DICOM) data of subjects meeting the selection criteria of the study were manually segmented by two experienced neurosurgeons. The hematoma segmentation model was built based on watershed algorithm and regional growth algorithm. Seed point selected by neurosurgeons was taken as the starting point of growth. Regional grayscale difference criterion combined with manual segmentation validation were adopted to determine the regional growth threshold that met the segmentation precision requirements for intracranial hematoma. Using manual segmentation as the gold standard, Bland-Altman consistency analysis was used to verify the consistency of the three other methods for measuring hematoma volume. Results: With manual segmentation as the gold standard, among the three methods of measuring hematoma volume, algorithm segmentation had the smallest percentage error, the narrowest range of difference, the highest intra-group correlation coefficient (0.987), good consistency, and the narrowest 95% limits of agreement ( LoA). The percentage error of its segmentation was not statistically significant for hematomas of different volumes. Conclusion: The segmentation method of spontaneous intracerebral hemorrhage based on watershed and regional growth algorithm shows stable measurement performance and good consistency with the clinical gold standard, which has considerable clinical significance, but it still needs further validation with more clinical samples.

[Application of Improved Unet Network in the Recognition and Segmentation of Hemorrhage Regions in Brain CT Images].

OBJECTIVE: To examine the performance and application value of improved Unet network technology in the recognition and segmentation of hemorrhage regions in brain CT images. METHODS: A total of 476 brain CT images of patients with spontaneous intracerebral hemorrhage (SICH) were retrospectively included. The improved Unet network was used to identify and segment the hemorrhage regions in the patients' brain CT images. The CT imaging data of the hemorrhage regions were manually labelled by clinicians. After randomized sorting, 430 data sets from 106 patients were selected for inclusion in the training set and 46 data sets from 11 patients were included in the test set. After data enhancement, the experimental data set underwent network training and model testing in order to assess the segmentation performance. The segmentation results were compared with the those of the Unet network (Base), FCN-8s network and Unet++ network. RESULTS: In the segmentation of brain CT image hemorrhage region with the improved Unet network, the three evaluation indicators of Dice similarity coefficient, positive predictive value (PPV), and sensitivity coefficient (SC) reached 0.8738, 0.9011 and 0.8648, respectively, increasing by 8.80%, 7.14% and 8.96%, respectively, compared with those of FCN-8s, and increasing by 4.56%, 4.44% and 4.15%, respectively, compared with those of Unet network (Base). The improved Unet network also showed better segmentation performance than that of Unet++ network. CONCLUSION: The improved method based on Unet network proposed in this report displayed good performance in the recognition and segmentation of hemorrhage regions in brain CT images, and is an appropriate method for the recognition and segmentation of hemorrhage regions in brain CT images, showing potential application value for assisting clinical decision-making and preventing early hematoma expansion.

Transamidation and Decarbonylation of N-Phthaloyl-Amino Acid Amides Enabled by Palladium-Catalyzed Selective C-N Bond Cleavage.

Amides are important functional synthons that have been widely used in the construction of peptides, natural products, and drugs. The C-N bond cleavage provides the direct method for amide conversion. However, amides, especially secondary amides, tend to be chemically inert due to the resonance of the amide bond. Here, we describe an efficient Pd-catalyzed transamidation and decarbonylation of multiamide structure molecules through C-N bond cleavage with excellent chemoselectivity. The transamidation of secondary amides and the decarbonylation of phthalimide provide meaningful tools for the modification of amino acid derivatives. Moreover, further transformations of azidation and C(sp3)-H monoarylation emphasized the potential utility of this selective C-N bond cleavage method.

Built-in Electric Field Triggered Interfacial Accumulation Effect for Efficient Nitrate Removal at Ultra-Low Concentration and Electroreduction to Ammonia.

A built-in electric field in electrocatalyst can significantly accumulate higher concentration of NO3 - ions near electrocatalyst surface region, thus facilitating mass transfer for efficient nitrate removal at ultra-low concentration and electroreduction reaction (NO3 RR). A model electrocatalyst is created by stacking CuCl (111) and rutile TiO2 (110) layers together, in which a built-in electric field induced from the electron transfer from TiO2 to CuCl (CuCl_BEF) is successfully formed . This built-in electric field effectively triggers interfacial accumulation of NO3 - ions around the electrocatalyst. The electric field also raises the energy of key reaction intermediate *NO to lower the energy barrier of the rate determining step. A NH3 product selectivity of 98.6 %, a low NO2 - production of <0.6 %, and mass-specific ammonia production rate of 64.4 h-1 is achieved, which are all the best among studies reported at 100 mg L-1 of nitrate concentration to date.

Red Zn2SiO4:Eu3+ and Mg2TiO4:Mn4+ nanophosphors for on-site rapid optical detections: Synthesis and characterization.

This study reports the synthesis and characterization of the red nanophosphors Zn2SiO4:Eu3+ (ZSO:Eu3+) and Mg2TiO4:Mn4+ (MTO:Mn4+). The use of phosphors as a fluorescence label for lateral flow immunochromatographic assay (LFIA) has also been described. The optimal photoluminescence (PL) for ZSO:Eu3+ was obtained when it was synthesized with 7 mol% of Eu3+ and annealed at 1100 °C for 1 h. Long fluorescence lifetime (1.01 ms), high activation energy E a (0.28 eV), and low PL degeneration (10% at 110 °C) are the characteristics of ZSO:Eu3+. MTO:Mn4+ also exhibited high PL intensity along with a high E a of 0.32 eV. The emission wavelengths of phosphors are biocompatible with the optical bio-window of tissues. When human immunoglobulin G (human IgG) at a constant concentration of 100 µg/mL was used for detection, the PL ratios of the test line to the control line were 2.15 and 2.28 for the ZSO:Eu3+- and MTO:Mn4+-labeled LFIA, respectively. Thus, the ZSO:Eu3+ and MTO:Mn4+ nanophosphors are capable of human IgG recognition and are the promising candidates as fluorescent labels for on-site rapid optical biodetection. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00339-021-04733-0.

Total Synthesis of (+)-Haperforin G.

A concise chemical synthesis of (+)-haperforin G in 20 steps from commercially available starting materials is achieved with the integration of the Co-catalyzed intramolecular Pauson-Khand reaction for the stereoselective construction of cyclopentanone bearing an all-carbon quaternary stereogenic center at the bridge-head position and the light-initiated photocatalysis for convergent and asymmetric cross-coupling of the unstabilized C(sp3)-radical with an enone. The developed chemistry paves the way to synthesizing structurally diverse analogs of haperforin G (6).

Prevalence and transmission of antimicrobial-resistant Staphylococci and Enterococci from shared bicycles in Chengdu, China.

Shared bicycles are prevailing in China but the extent to which they contribute to maintaining and transmitting pathogens and antibiotic-resistant bacteria remain largely unknown. To fill the knowledge gap, herein, swab samples (n = 963) were collected from handlebars of shared bicycles in areas of hospital, school, metro station (n = 887) and riders (n = 76) in Chengdu, China. Staphylococci (n = 241) and Enterococci (n = 69) were widely distributed across sampling locations at a frequency of 2.3%-12.9%, and 0.08%-5.5%, respectively. Bicycle or rider-borne Gram-positive bacteria were frequently resistant to clinically important antibiotics including linezolid, fosfomycin, and vancomycin, and a significant portion of these isolates (3.4%-16.6% for Staphylococci and 0.1%-13.8% for Enterococci) indicated multidrug resistance. Nineteen Staphylococcus aureus isolates were identified in this collection and 52.6% of which were considered as methicillin-resistant S. aureus. Whole genome sequencing further characterized 26 antimicrobial resistance genes (ARGs) including fosB, fusB, and lnu(G) in S. aureus and 21 ARGs including optrA in Enterococci. Leveraging a complementary approach with conventional MLST, whole genome SNP and MLST analyses, we present that genetically closely-related bacteria were found in bicycles and riders across geographical-distinct locations suggesting bacterial transmission. Further, five new ST types 5697-5701 were firstly characterized in S. aureus. ST 942 and ST 1640 are new ST types observed in E. faecalis, and E. faecium, respectively. Our results highlighted the risk of shared bicycle system in disseminating pathogens and antibiotic resistance which warrants effective disinfections.

Potent In Vitro Synergism of Fluconazole and Osthole against Fluconazole-Resistant Candida albicans.

Osthole is a natural coumarin that exhibits wide biological and pharmacological activities such as neuroprotective, osteogenic, immunomodulation, antitumor, and anti-inflammatory effects. In this study, we investigated the antifungal effects of osthole in vitro A checkerboard microdilution assay showed that osthole has significant synergistic effect with fluconazole against fluconazole-resistant Candida albicans Similar results were obtained from a growth curve assay. Meanwhile, XTT reduction assay demonstrated the synergism of fluconazole and osthole against C. albicans biofilm formation. Microarray results showed that the expression of genes involved in the oxidation-reduction process, energy metabolism, and transportation changed significantly after the combined treatment with fluconazole and osthole, and further results showed that endogenous reactive oxygen species (ROS) was significantly increased in the combination group. In conclusion, these results demonstrate the synergism of fluconazole and osthole against fluconazole-resistant C. albicans and indicate that endogenous ROS augmentation might contribute to the synergism of fluconazole and osthole.

A Case Involving Needles in the Medulla Oblongata, Cervical Spinal Cord, and Abdomen.

It is extremely rare to encounter intracranial foreign bodies caused by penetrating injuries other than gunshot wounds or low-velocity wounds. We present a case describing a 5-year-old girl with metallic foreign bodies in the medulla oblongata, cervical spinal cord, and abdomen. The foreign bodies may have been there and remained silent for several years until the patient developed nausea and vomiting that persisted for 3 months. A craniotomy and a laparotomy were performed after a thorough discussion. Five pieces of metallic foreign bodies were removed, and the patient had a good outcome. Despite the precarious location of the needles in the medulla oblongata and cervical spinal cord, this rare case supports the use of surgery to remove the foreign bodies.