2D Ultrathin Titanium Nitride Nanosheets as Separator Coatings for Li-S Batteries.

Transition metal nitrides (TMNs) are affirmed to be an appealing candidate for boosting the performance of lithium-sulfur (Li-S) batteries due to their excellent conductivity, strong interaction with sulfur species, and the effective catalytic ability for conversion of polysulfides. However, the traditional bulk TMNs are difficult to achieve large active surface area and fast transport channels for electrons/ions simultaneously. Here, a 2D ultrathin geometry of titanium nitride (TiN) is realized by a facile topochemical conversion strategy, which can not only serve as an interconnected conductive platform but also expose abundant catalytic active sites. The ultrathin TiN nanosheets are coated on a commercial separator, serving as a multifunctional interlayer in Li-S batteries for hindering the polysulfide shuttle effect by strong capture and fast conversion of polysulfides, achieving a high initial capacity of 1357 mAh g-1 at 0.1 C and demonstrating a low capacity decay of only 0.046% per cycle over 1000 cycles at 1 C.

The GG genotype of rs743572 in CYP17A1 gene regulating the decrease of T/E ratio can be an independent risk factor for MetS-BPH: a retrospective cohort study.

PURPOSE: To confirm if the CYP17A1 gene regulates the ratio of T/E leading to MetS-BPH. METHODS: 824 men, aged 47-88 years, were recruited into this study through consecutive routine physical examination programs and long-term outpatient screening. Several parameters, including SNPs of CYP17A1 gene, total testosterone, estradiol, and the ratio of total testosterone to estradiol (T/E) were obtained for each participant. Based on the diagnosis of BPH, MetS, and MetS-BPH, the participants were divided into BPH and non-BPH groups, MetS and non-MetS groups, and MetS-BPH and non-MetS-BPH groups. Values of the obtained parameters were evaluated using one-way analysis of variance, Student's t-test, Chi-squared test, and logistic regression analysis. RESULTS: SNPs of the CYP17A1 gene, including the rs743572 genotypes (GG, GA, and AA), rs3781287 genotypes (GG, GT, TT), and rs4919686 genotypes (CC, CA, and AA), were present in every group. Only the GG genotype of rs743572 was independently associated with BPH (OR = 5.868, 95% CI: 3.363-7.974, P < 0.001), MetS (OR = 7.228, 95% CI: 3.925-11.331, P < 0.001), and MetS-BPH (OR = 3.417, 95% CI: 1.783-5.266, P < 0.001) after adjusting for age. In the population of genotype GG of rs743572, the decrease in T/E ratio was an independent risk factor for BPH (OR = 839.756, 95% CI: 36.978-1334.263, P = 0.001), MetS (OR = 376.988, 95% CI: 12.980-488.976, P < 0.003), and MetS-BPH (OR = 388.236, 95% CI: 24.869-495.363, P = 0.003). CONCLUSION: The GG genotype of rs743572 in CYP17A1 gene regulating the decrease of T/E ratio can be an independent risk factor for MetS-BPH populations. TRIAL REGISTRATION NUMBER: ChiCTR2200057632 "retrospectively registered". DATE OF REGISTRATION: March 15, 2022 "retrospectively registered".

Extremely efficient terahertz high-harmonic generation in graphene by hot Dirac fermions.

Multiple optical harmonic generation-the multiplication of photon energy as a result of nonlinear interaction between light and matter-is a key technology in modern electronics and optoelectronics, because it allows the conversion of optical or electronic signals into signals with much higher frequency, and the generation of frequency combs. Owing to the unique electronic band structure of graphene, which features massless Dirac fermions1-3, it has been repeatedly predicted that optical harmonic generation in graphene should be particularly efficient at the technologically important terahertz frequencies4-6. However, these predictions have yet to be confirmed experimentally under technologically relevant operation conditions. Here we report the generation of terahertz harmonics up to the seventh order in single-layer graphene at room temperature and under ambient conditions, driven by terahertz fields of only tens of kilovolts per centimetre, and with field conversion efficiencies in excess of 10-3, 10-4 and 10-5 for the third, fifth and seventh terahertz harmonics, respectively. These conversion efficiencies are remarkably high, given that the electromagnetic interaction occurs in a single atomic layer. The key to such extremely efficient generation of terahertz high harmonics in graphene is the collective thermal response of its background Dirac electrons to the driving terahertz fields. The terahertz harmonics, generated via hot Dirac fermion dynamics, were observed directly in the time domain as electromagnetic field oscillations at these newly synthesized higher frequencies. The effective nonlinear optical coefficients of graphene for the third, fifth and seventh harmonics exceed the respective nonlinear coefficients of typical solids by 7-18 orders of magnitude7-9. Our results provide a direct pathway to highly efficient terahertz frequency synthesis using the present generation of graphene electronics, which operate at much lower fundamental frequencies of only a few hundreds of gigahertz.

Clinical comparison of lateral supine position mini-percutaneous nephrolithotomy and anatrophic nephrolithotomy in the treatment of complete staghorn renal calculi.

BACKGROUND: At present, the guidelines for urology recommend percutaneous nephrolithotomy (PCNL) as the preferred treatment for staghorn renal calculi (SRC). However, for complete SRC, it has been questioned by clinicians and patients due to high residual stone rate, complications, repeated hospitalizations and high treatment cost. Anatrophic nephrolithotomy (ANL) is a traditional and classic method for the treatment of SRC. Due to its high trauma and high technical requirements, it is difficult to carry out in primary hospitals, and gradually replaced by PCNL. The purpose of this study is to compare the efficacy of PCNL and ANL in the treatment of complete SRC. METHODS: Overall, 238 patients with complete SRC were divided into mini-PCNL in lateral supine position group, (n = 190) and ANL group (n = 94) according to treatment for a retrospective cohort study. The calculi parameters, renal function index, comorbidities of calculi, surgical complications, length and frequency of hospitalization, treatment costs, results of postoperative satisfaction survey were compared between the two groups. RESULTS: The risk of the residual stone rate after mini-PCNL in lateral supine position was 239 times (OR = 238.667, P < 0.0001), the number of residual stone 1.3 times (OR = 1.326, P < 0.0001), the amount of residual stone 2.2 times (OR = 2.224, P < 0.0001) that of ANL. The risk of the cost of initial treatment after mini-PCNL in lateral supine position was 3.3 times (OR = 3.273, P < 0.0001), the total cost of treatment 4 times (OR = 4.051, P < 0.0001), the total length of hospital stays 1.4 times (OR = 1.44, P < 0.0001) that of ANL, the incidence of postoperative renal atrophy was 2.2 times (OR = 2.171, P = 0.008) higher in the ANL than in the mini-PCNL in lateral supine position. Glomerular filtration rate (GFR) reduction after ANL was 1.4 times (OR = 1.381, P = 0.037) greater than that after mini-PCNL in lateral supine position at 24-month follow-up. The risk of the overall satisfaction of ANL was 58 times (OR = 57.857, P < 0.0001) higher than that of mini-PCNL in lateral supine position, the number of branches of staghorn greater than 8 is a high risk factor for the occurrence of residual stone after mini-PCNL in lateral supine position (OR = 353.137, P < 0.0001). CONCLUSION: Although the risk of renal atrophy and decreased GFR after ANL is higher than that of mini-PCNL in lateral supine position, the efficacy of traditional ANL in the treatment of complete SRC was generally superior to that of mini-PCNL in lateral supine position. Moreover, number of branches of staghorn greater than 8 are the preferred ANL for complete SRC. TRIAL REGISTRATION: ChiCTR2100047462. The trial was registered in the Chinese Clinical Trial Registry; registration date: 19/06/2021.

Synthesis and Self-Assembly of Ultrathin Holey Graphdiyne Nanosheets for Oxygen Reduction Reaction.

Graphdiyne (GDY) is a fascinating graphene-like 2D carbon allotrope comprising sp and sp2 hybridized carbon atoms. However, GDY materials synthesized by solution-phase methods normally come as thick and porous films or amorphous powders with severely disordered stacking modes that obstruct macroscopic applications. Here, a facile and scalable synthesis of ultrathin holey graphdiyne (HGDY) nanosheets is reported via palladium/copper co-catalyzed homocoupling of 1,3,5-triethynylbenzene. The resulting freestanding 2D HGDY self-assembles into 3D foam-like networks which can in situ anchor clusters of palladium atoms on their surfaces. The Pd/HGDY hybrids exhibit high electrocatalytic activity and stability for the oxygen reduction reaction which outperforms that of Pt/C benchmark. Based on the ultrathin graphene-like sheets and their unique 3D interconnected macrostructures, Pd/HGDY holds great promise for practical electrochemical catalysis and energy-related applications.

Bottom-Up, On-Surface-Synthesized Armchair Graphene Nanoribbons for Ultra-High-Power Micro-Supercapacitors.

Bottom-up-synthesized graphene nanoribbons (GNRs) with excellent electronic properties are promising materials for energy storage systems. Herein, we report bottom-up-synthesized GNR films employed as electrode materials for micro-supercapacitors (MSCs). The micro-device delivers an excellent volumetric capacitance and an ultra-high power density. The electrochemical performance of MSCs could be correlated with the charge carrier mobility within the differently employed GNRs, as determined by pump-probe terahertz spectroscopy studies.

The underlying mechanism of metabolic syndrome on benign prostatic hyperplasia and prostate volume.

OBJECTIVE: To investigate the potential mechanism of the effect of metabolic syndrome (MetS) on prostate volume (PV) and the risk of benign prostatic hyperplasia (BPH)/lower urinary tract symptoms (LUTS) and the relationships of MetS and the major pathogenic factors of MetS with the clinical progression of BPH/LUTS in older Chinese men. SUBJECTS AND METHODS: We analyzed clinical data obtained from 506 ostensibly healthy men who underwent routine health check-ups and recruited 415 subjects from a group of previously studied men after 4 years. We evaluated the associations of major pathological factors of MetS, including insulin resistance, subclinical inflammatory state, and sex hormone changes, with PV, the risk of BPH and the clinical progression of BPH/LUTS by using multiple linear regression and logistic regression. RESULTS: After adjustment for age, insulin, HOMA (homeostatic model assessment) index, leptin, resistin, adiponectin, C-reactive protein, tumor necrosis factor-α (TNF-α), sex hormone-binding globulin, and testosterone levels were significantly associated with PV (all P < .05), and in the age-adjusted logistic regression model, positive associations of resistin and TNF-α with BPH/LUTS were found (OR, 1.662, P = .007 and OR, 1.044, P < .001, respectively). Predictors of BPH/LUTS clinical progression were significantly correlated with MetS and TNF-α. The group with higher TNF-α levels had a higher rate of newly diagnosed BPH (9.5% vs 19.1%, P = .006) and a greater increase in PV levels (0.61 ± 0.08 vs 1.09 ± 0.35 cm3 , P <.001) after 4 years. CONCLUSIONS: MetS and its pathological factors were associated with an increased PV and an increased risk of BPH/LUTS that is more prone to clinical progression. TNF-α may serve as an early biological indicator to identify which patients with BPH/LUTS are at higher risk of unfavorable outcomes.

Hysteresis in graphene nanoribbon field-effect devices.

Hysteresis in the current response to a varying gate voltage is a common spurious effect in carbon-based field effect transistors. Here, we use electric transport measurements to probe the charge transport in networks of armchair graphene nanoribbons with a width of either 5 or 9 carbon atoms, synthesized in a bottom-up approach using chemical vapor deposition. Our systematic study on the hysteresis of such graphene nanoribbon transistors, in conjunction with temperature-dependent transport measurements shows that the hysteresis can be fully accounted for by trapping/detrapping carriers in the SiO2 layer. We extract the trap densities and depth, allowing us to identify shallow traps as the main origin of the hysteresis effect.

Kinetic Ionic Permeation and Interfacial Doping of Supported Graphene.

Due to its outstanding electrical properties and chemical stability, graphene finds widespread use in various electrochemical applications. Although the presence of electrolytes strongly affects its electrical conductivity, the underlying mechanism has remained elusive. Here, we employ terahertz spectroscopy as a contact-free means to investigate the impact of ubiquitous cations (Li+, Na+, K+, and Ca2+) in aqueous solution on the electronic properties of SiO2-supported graphene. We find that, without applying any external potential, cations can shift the Fermi energy of initially hole-doped graphene by ∼200 meV up to the Dirac point, thus counteracting the initial substrate-induced hole doping. Remarkably, the cation concentration and cation hydration complex size determine the kinetics and magnitude of this shift in the Fermi level. Combined with theoretical calculations, we show that the ion-induced Fermi level shift of graphene involves cationic permeation through graphene. The interfacial cations located between graphene and SiO2 electrostatically counteract the substrate-induced hole doping effect in graphene. These insights are crucial for graphene device processing and further developing graphene as an ion-sensing material.

The association of pathogenic factors of metabolic syndrome on serum prostate-specific antigen levels: a pilot study.

BACKGROUND: Metabolic syndrome (MetS) and serum prostate-specific antigen (PSA) levels are correlated. To investigate the underlying effect of MetS on PSA levels, the relationship between the major pathogenic factors of MetS and serum PSA levels was studied. METHODS: A total of 506 ostensibly healthy men who underwent routine health check-ups were recruited to this study. We evaluated the effect of the major pathogenic factors of MetS, which included insulin resistance, a subclinical inflammatory state and sexual hormone changes, on serum PSA levels by using linear regression analysis and multivariate analysis after adjusting for age, BMI and prostate volume. RESULTS: When simultaneously adjusting for age, BMI, prostate volume and high-density lipoprotein cholesterol, serum insulin levels and SHBG levels were inversely correlated with serum PSA levels (P = 0.049 and P = 0.004, respectively), and testosterone levels were positively correlated with serum PSA levels (P = 0.039). In multivariate regression models, serum insulin levels and serum SHBG levels were significantly associated with serum PSA levels (both P < 0.001). CONCLUSIONS: Among the major pathogenic factors of metabolic syndrome, insulin resistance and sexual hormone changes may be the most significant contributors to the decline in serum PSA levels.

Lateral Fusion of Chemical Vapor Deposited N = 5 Armchair Graphene Nanoribbons.

Bottom-up synthesis of low-bandgap graphene nanoribbons with various widths is of great importance for their applications in electronic and optoelectronic devices. Here we demonstrate a synthesis of N = 5 armchair graphene nanoribbons (5-AGNRs) and their lateral fusion into wider AGNRs, by a chemical vapor deposition method. The efficient formation of 10- and 15-AGNRs is revealed by a combination of different spectroscopic methods, including Raman and UV-vis-near-infrared spectroscopy as well as by scanning tunneling microscopy. The degree of fusion and thus the optical and electronic properties of the resulting GNRs can be controlled by the annealing temperature, providing GNR films with optical absorptions up to ∼2250 nm.

Chemical Vapor Deposition Synthesis and Terahertz Photoconductivity of Low-Band-Gap N = 9 Armchair Graphene Nanoribbons.

Recent advances in bottom-up synthesis of atomically defined graphene nanoribbons (GNRs) with various microstructures and properties have demonstrated their promise in electronic and optoelectronic devices. Here we synthesized N = 9 armchair graphene nanoribbons (9-AGNRs) with a low optical band gap of ∼1.0 eV and extended absorption into the infrared range by an efficient chemical vapor deposition process. Time-resolved terahertz spectroscopy was employed to characterize the photoconductivity in 9-AGNRs and revealed their high intrinsic charge-carrier mobility of approximately 350 cm2·V-1·s-1.

Monitoring the On-Surface Synthesis of Graphene Nanoribbons by Mass Spectrometry.

We present a mass spectrometric approach to characterize and monitor the intermediates of graphene nanoribbon (GNR) formation by chemical vapor deposition (CVD) on top of Au(111) surfaces. Information regarding the repeating units, lengths, and termini can be obtained directly from the surface sample by a modified matrix-assisted laser desorption/ionization (MALDI) method. The mass spectrometric results reveal ample oxidative side reactions under CVD conditions that can be drastically diminished by the introduction of protective H2 gas at ambient pressure. Simultaneously, the addition of hydrogen extends the lengths of the oligophenylenes and thus the final GNRs. Moreover, the prematurely formed cyclodehydrogenation products during the oligomer growth can be assigned by the mass spectrometric technique. The obtained mechanistic insights provide valuable information for optimizing and upscaling the bottom-up fabrication of GNRs. Given the important role of GNRs as semiconductors, the mass spectrometric analysis provides a readily available tool to characterize and improve their structural perfection.

Synthesis of Graphene Nanoribbons by Ambient-Pressure Chemical Vapor Deposition and Device Integration.

Graphene nanoribbons (GNRs), quasi-one-dimensional graphene strips, have shown great potential for nanoscale electronics, optoelectronics, and photonics. Atomically precise GNRs can be "bottom-up" synthesized by surface-assisted assembly of molecular building blocks under ultra-high-vacuum conditions. However, large-scale and efficient synthesis of such GNRs at low cost remains a significant challenge. Here we report an efficient "bottom-up" chemical vapor deposition (CVD) process for inexpensive and high-throughput growth of structurally defined GNRs with varying structures under ambient-pressure conditions. The high quality of our CVD-grown GNRs is validated by a combination of different spectroscopic and microscopic characterizations. Facile, large-area transfer of GNRs onto insulating substrates and subsequent device fabrication demonstrate their promising potential as semiconducting materials, exhibiting high current on/off ratios up to 6000 in field-effect transistor devices. This value is 3 orders of magnitude higher than values reported so far for other thin-film transistors of structurally defined GNRs. Notably, on-surface mass spectrometry analyses of polymer precursors provide unprecedented evidence for the chemical structures of the resulting GNRs, especially the heteroatom doping and heterojunctions. These results pave the way toward the scalable and controllable growth of GNRs for future applications.

Flexible graphene-based lithium ion batteries with ultrafast charge and discharge rates.

There is growing interest in thin, lightweight, and flexible energy storage devices to meet the special needs for next-generation, high-performance, flexible electronics. Here we report a thin, lightweight, and flexible lithium ion battery made from graphene foam, a three-dimensional, flexible, and conductive interconnected network, as a current collector, loaded with Li(4)Ti(5)O(12) and LiFePO(4), for use as anode and cathode, respectively. No metal current collectors, conducting additives, or binders are used. The excellent electrical conductivity and pore structure of the hybrid electrodes enable rapid electron and ion transport. For example, the Li(4)Ti(5)O(12)/graphene foam electrode shows a high rate up to 200 C, equivalent to a full discharge in 18 s. Using them, we demonstrate a thin, lightweight, and flexible full lithium ion battery with a high-rate performance and energy density that can be repeatedly bent to a radius of 5 mm without structural failure and performance loss.

Superhydrophobic graphene foams.

The static and dynamic wetting properties of a 3D graphene foam network are reported. The foam is synthesized using template-directed chemical vapor deposition and contains pores several hundred micrometers in dimension while the walls of the foam comprise few-layer graphene sheets that are coated with Teflon. Water contact angle measurements reveal that the foam is superhydrophobic with an advancing contact angle of ∼163 degrees while the receding contact angle is ∼143 degrees. The extremely water repellent nature of the foam is also confirmed when impacting water droplets are able to completely rebound from the surface. Such superhydrophobic graphene foams show potential in a variety of applications ranging from anti-sticking and self-cleaning to anti-corrosion and low-friction coatings.

Two-Dimensional Atomically Thin Titanium Nitride via Topochemical Conversion.

Titanium nitride as a typical transition metal nitride (TMN) has attracted increasing interest for its fascinating characteristics and widespread applications. However, the synthesis of two-dimensional (2D) atomically thin titanium nitride is still challenging which hinders its further research in electronic and optoelectronic fields. Here, 2D titanium nitride with a large area was prepared via in situ topochemical conversion of the titanate monolayer. The titanium nitride reveals a thickness-dependent metallic-to-semiconducting transition, where the atomically thin titanium nitride with a thickness of ∼1 nm exhibits an n-type semiconducting behavior and a highly sensitive photoresponse and displays photoswitchable resistance by repeated light irradiation. First-principles calculations confirm that the chemisorbed oxygen on the surface of the titanium nitride nanosheet depletes its electrons, while the light irradiation induced desorption of oxygen leads to increased electron doping and hence the conductance of titanium nitride. These results may allow the scalable synthesis of ultrathin TMNs and facilitate their fundamental physics research and next-generation optoelectronic applications.

Three-dimensional flexible and conductive interconnected graphene networks grown by chemical vapour deposition.

Integration of individual two-dimensional graphene sheets into macroscopic structures is essential for the application of graphene. A series of graphene-based composites and macroscopic structures have been recently fabricated using chemically derived graphene sheets. However, these composites and structures suffer from poor electrical conductivity because of the low quality and/or high inter-sheet junction contact resistance of the chemically derived graphene sheets. Here we report the direct synthesis of three-dimensional foam-like graphene macrostructures, which we call graphene foams (GFs), by template-directed chemical vapour deposition. A GF consists of an interconnected flexible network of graphene as the fast transport channel of charge carriers for high electrical conductivity. Even with a GF loading as low as ∼0.5 wt%, GF/poly(dimethyl siloxane) composites show a very high electrical conductivity of ∼10 S cm(-1), which is ∼6 orders of magnitude higher than chemically derived graphene-based composites. Using this unique network structure and the outstanding electrical and mechanical properties of GFs, as an example, we demonstrate the great potential of GF/poly(dimethyl siloxane) composites for flexible, foldable and stretchable conductors.

Failure Criteria and Constitutive Relationship of Lightweight Aggregate Concrete under Triaxial Compression.

This paper investigates the compression behavior and failure criteria of lightweight aggregate concrete (LAC) under triaxial loading. A total of 156 specimens were tested for three parameters: concrete strength, lateral confining pressure and aggregate immersion time, and their effects on the failure mode of LAC and the triaxial stress-strain relationship of LAC is studied. The research indicated that, as the lateral constraint of the specimen increases, the failure patterns change from vertical splitting failure to oblique shearing failure and then to indistinct traces of damage. The stress-strain curve of LAC specimens has an obvious stress plateau, and the curve no longer appears downward when the confining pressure exceeds 12 MPa. According to the experimental phenomenon and test data, the failure criterion was examined on the Mohr-Coulomb theory, octahedral shear stress theory and Rendulic plane stress theory, which well reflects the behavior of LAC under triaxial compression. For the convenience of analysis and application, the stress-strain constitutive models of LAC under triaxial compression are recommended, and these models correlate well with the test results.

Experimental Study on Triaxial Compressive Mechanical Properties of Polypropylene Fiber Coral Seawater Concrete.

In order to study the mechanical properties of polypropylene fiber all-coral seawater concrete in triaxial compression, 36 specimens were developed and constructed for triaxial compression load testing employing confining pressure value (0, 6, 12, 18 MPa) and polypropylene fiber admixture (1 kg·m-3, 2 kg·m-3, 3 kg·m-3) as variation parameters. The test observed the failure mode of the specimen and obtained the stress-strain curve of the whole process of its force damage failure. An in-depth analysis of polypropylene fiber all-coral seawater concrete's peak stress, peak strain, initial elastic modulus, axial deflection, energy dissipation, ductility, and damage evolution process was carried out based on the experimental data. The test findings indicated that the best effect on the deformation properties of polypropylene fiber all-coral seawater concrete is obtained when 3 kg·m-3 of polypropylene fiber is blended. Under triaxial compression, the correct number of polypropylene fibers may significantly enhance the peak stress, peak strain, ductility, and elastic modulus of polypropylene fiber all-coral seawater concrete, therefore enhancing the brittle characteristics of coral concrete. During the triaxial surround pressure test, the confining pressure value and polypropylene fiber coupling effect delayed the appearance of initial damage in polypropylene fiber complete coral seawater concrete specimens, slowed the development of damage, and reduced the degree of damage to the specimens.