Experimental investigation on weak shock wave mitigation characteristics of flexible polyurethane foam and polyurea

In recent years,explosion shock wave has been considered as a signature injury of the current military conflicts.Although strong shock wave is lethal to the human body,weak shock wave can cause many more lasting consequences.To investigate the protection ability and characteristics of flexible materials and structures under weak shock wave loading,the blast wave produced by TNT explosive is loaded on the polyurethane foam with the density of 200.0 kg/m3(F-200)and 400.0 kg/m3(F-400),polyurea with the density of 1100.0 kg/m^(3)(P-1100)and structures composed of the two materials,which are intended for individual protection.Experimental results indicate that the shock wave is attenuated to weak pressure disturbance after interacting with the flexible materials which are not damaged.The shock wave protective capability of single-layer materials is dependent on their thickness,density and microscopic characteristics.The overpressure,maximum pressure rise rate and impulse of transmitted wave decrease exponentially with increase in sample thickness.For the same thickness,F-400 provides better protective capability than F-200 while P-1100 shows the best protective capability among the three materials.In this study,as the materials are not destroyed,F-200 with a thickness more than10.0 mm,F-400 with a thickness more than 4.0 mm,and P-1100 with a thickness more than 1.0 mm can attenuate the overpressure amplitude more than 90.0%.Further,multi-layer flexible composites are designed.Different layer layouts of designed structures and layer thickness of the single-layer materials can affect the protective performance.Within the research range,the structure in which polyurea is placed on the impact side shows the optimal shock wave protective performance,and the thicknesses of polyurea and polyurethane foam are 1.0 mm and 4.0 mm respectively.The overpressure attenuation rate reached maximum value of 93.3%and impulse attenuation capacity of this structure are better than those of single-layer polyurea and polyurethane foam with higher areal density.

Cys C、C1q、β_(2)-MG、Urea、UA检测对初诊多发性骨髓瘤患者合并肾损伤的诊断价值

目的探讨肾功能指标胱抑素C(cystatin C,Cys C)、补体C1q(complement C1q)、β_(2)-微球蛋白(β_(2)-microglobulin,β_(2)-MG)、尿素(Urea)、尿酸(uric acid,UA)对初诊多发性骨髓瘤(multiplemyeloma,MM)患者合并肾损伤(renal impairment,RI)的诊断价值。方法回顾性分析2021年8月~2022年12月首都医科大学附属北京积水潭医院血液科收治的93例初诊MM患者的病例资料,按照血肌酐水平将MM患者分为RI组[血肌酐>176.80mmol/L(2mg/dl),n=19]及非RI组[血肌酐≤176.80mmol/L(2mg/dl),n=74],对RI组和非RI组的临床资料及实验室指标进行分析。采用单因素和多因素Logistic回归分析评价MM患者发生RI的危险因素,应用受试者工作特征(receiver operating characteristic,ROC)曲线评估危险因素对MM患者发生RI的预测价值。结果93例初诊MM患者发生RI者占25.68%,RI组轻链型占比最高(36.84%,7/19),IgG-λ型和IgA-κ型比例最低(10.53%,2/19);非RI组IgA-κ型比例最高(29.73%,22/74),IgG-λ型比例最低(12.16%,9/74)。DS分期中,RI组19例全部为Ⅲ期,非RI组72例全部为Ⅲ期。ISS分期中,RI组Ⅲ期最多(68.42%,13/19),非RI组中Ⅰ期最多(41.89%,31/74)。RISS分期中,RI组Ⅱ期和Ⅲ期最多(36.84%,7/19),非RI组Ⅱ期最多(58.11%,43/74)。DS分期和ISS分期组间差异有统计学意义(P<0.05)。RI组中Cys C、β_(2)-MG、Urea、UA水平均高于非RI组,差异均有统计学意义(P<0.05)。单因素分析结果显示,Cys C、Urea、β_(2)-MG水平异常升高是MM患者发生RI的危险因素(P<0.05),C1q对MM患者发生RI没有影响(P>0.05);多因素Logistic回归分析结果显示,Cys C、Urea、β_(2)-MG水平异常升高均是MM患者发生RI的独立影响因素(P<0.05)。Cys C、Urea、β_(2)-MG预测MM患者发生RI的敏感度分别为88.9%、50.0%、94.4%,特异性分别为90.4%、100.0%、84.9%;Cys C、Urea、β_(2)-MG联合检测预测MM患者发生RI的敏感度为100.0%,特异性为87.7%。结论Cys C、Urea、β_(2)-MG均能较好地预测初诊MM患者发生RI的可能性,3项指标联合检测对MM患者发生RI具有更高的预测价值。

Effect of Amine Type on Lignin Modification to Evaluate Its Reactivity in Polyol Construction for Non-Isocyanate Polyurethanes(NIPU)

Polyols are groups of organic compounds which contain carbon and are randomly linked to other atoms,especially carbon-carbon and carbon-hydrogen.These compounds are mainly used as reactants to make other polymers.Among biopolymers,lignin is regarded as the base of a new polymer in polyol construction.The present study aimed to investigate the effects of amine type(diethylenetriamine and ethylenediamine)on the modification of lignin-based polyols,so as to provide an alternative to petroleum polyols and,in turn,increase functional groups and reduce their harm to humans’health and the environment.To this aim,first,lignin was extracted from raw liquor.Next,the extracted lignin was reacted with diethylenetriamine(DETA)and ethylenediamine(EDA).Finally,the Mannich method was used for the reaction between amine lignin and propylene carbonate.The results of the Fourier Transform Infrared(FTIR)spectroscopy analysis showed that modification with DETA led to more structural change in lignin and peak 1100 indicates the presence of C–O bond related to urethane bonds in modified lignin.Moreover,adding propylene carbonate to aminated lignin did not result in much change in the results of the FTIR analysis.Additionally,urethane bonds can be seen in the results of GPC at 400℃–500℃.Furthermore,a slight decrease in thermal stability was observed in lignin modified with amine and propylene carbonate,compared to the raw lignin sample.

Hydrolysable Chestnut Tannin Extract Chemical Complexity in Its Reactions for Non-Isocyanate Polyurethanes(NIPU)Foams

Non-isocyanate polyurethane(NIPU)foams from a commercial hydrolysable tannin extract,chestnut wood tannin extract,have been prepared to determine what chemical species and products are taking part in the reactions involved.This method is based on two main steps:the reaction with dimethyl carbonate and the formation of urethane bonds by further reaction of the carbonated tannin with a diamine-like hexamethylene diamine.The hydroxyl groups on the tannin polyphenols and on the carbohydrates intimately linked with it and part of a hydrolysable tannin are the groups involved in these reactions.The carbohydrate skeleton of the hydrolysable tannin is also able to participate through its hydroxyl groups to the same two reactions rendering the whole molecular complex able to react to form NIPUs.The analysis by Matrix-Assisted Laser Desorption Ionization(MALDI-TOF)mass spectrometry and 13C Nuclear Magnetic Resonance(13C NMR)to further investigate the reaction mechanisms involved revealed the unsuspected complexity of chestnut hydrolysable tannin,with different fragments reacting in different manners forming a hardened network of considerable complexity.As the morphology and performance of these types of foams changes slightly with the change in the amount of glutaraldehyde and hexamine hardeners,the best performing foam formulation previously determined was scanned by SEM and analysed chemically for the structures formed.

Microwave-assisted exploration of the electron configuration-dependent electrocatalytic urea oxidation activity of 2D porous NiCo_(2)O_(4) spinel

Urea holds promise as an alternative water-oxidation substrate in electrolytic cells.High-valence nickelbased spinel,especially after heteroatom doping,excels in urea oxidation reactions(UOR).However,traditional spinel synthesis methods with prolonged high-temperature reactions lack kinetic precision,hindering the balance between controlled doping and highly active two-dimensional(2D)porous structures design.This significantly impedes the identification of electron configuration-dependent active sites in doped 2D nickel-based spinels.Herein,we present a microwave shock method for the preparation of 2D porous NiCo_(2)O_(4)spinel.Utilizing the transient on-off property of microwave pulses for precise heteroatom doping and 2D porous structural design,non-metal doping(boron,phosphorus,and sulfur)with distinct extranuclear electron disparities serves as straightforward examples for investigation.Precise tuning of lattice parameter reveals the impact of covalent bond strength on NiCo_(2)O_(4)structural stability.The introduced defect levels induce unpaired d-electrons in transition metals,enhancing the adsorption of electron-donating amino groups in urea molecules.Simultaneously,Bode plots confirm the impact mechanism of rapid electron migration caused by reduced band gaps on UOR activity.The prepared phosphorus-doped 2D porous NiCo_(2)O_(4),with optimal electron configuration control,outperforms most reported spinels.This controlled modification strategy advances understanding theoretical structure-activity mechanisms of high-performance 2D spinels in UOR.

Pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy for activating water and urea oxidation

Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.

Hollow Ni Mo-based nitride heterojunction with super-hydrophilic/aerophobic surface for efficient urea-assisted hydrogen production

Hydrogen evolution reaction(HER)and urea oxidation reaction(UOR)are key reactions of the watercycling associated catalytic process/device.The design of catalysts with a super-hydrophilic/aerophobic structure and optimized electron distribution holds great promise.Here,we have designed a threedimensional(3D)hollow Ni/NiMoN hierarchical structure with arrayed-sheet surface based on a onepot hydrothermal route for efficient urea-assisted HER based on a simple hydrothermal process.The Ni/NiMoN catalyst exhibits super-hydrophilic/aerophobic properties with a small droplet contact angle of 6.07°and an underwater bubble contact angle of 155.7°,thus facilitating an escape of bubbles from the electrodes.Density functional theory calculations and X-ray photoelectron spectroscopy results indicate the optimized electronic structure at the interface of Ni and NiMoN,which can promote the adsorption/desorption of reactants and intermediates.The virtues combining with a large specific surface area endow Ni/NiMoN with efficient catalytic activity of low potentials of 25 mV for HER and 1.33 V for UOR at10 mA cm^(-2).The coupled HER and UOR system demonstrates a low cell voltage of 1.42 V at 10 mA cm^(-2),which is approximately 209 mV lower than water electrolysis.

Atomically dispersed Ni electrocatalyst for superior urea-assisted water splitting

Urea oxidation reaction(UOR) has been selected as substitution for oxygen evolution reaction ascribing to its low thermodynamic voltage as well as utilization of nickel as electrocatalyst.Herein,we report the formation of nickel single atoms(Ni-SAs) as exceptional bifunctional electrocatalyst toward UOR and hydrogen evolution reaction(HER) in urea-assisted water splitting.In UOR catalysis,Ni-SAs perform a superior catalytic performance than Ni-NP/NC and Pt/C ascribing to the formation of HOO-Ni-N_(4) structure evidenced by in-situ Raman spectroscopy,corresponding to a boosted mass activity by 175-fold at 1.4 V vs.RHE than Ni-NP/NC.Furthermore,Ni-SAs requires only 450 mV overpotential to obtain HER current density of 500 mA cm^(-2).136 mA cm^(-2) is achieved in urea-assisted water splitting at1.7 V for Ni-SAs,boosted by 5.7 times than Pt/C-IrO_(2) driven water splitting.

Synthesis and Characterization of Nonionic Waterborne Polyurethane and Application to Wool Fabric Finishing

A nonionic waterborne polyurethane(WPU) was synthesized by the self-emulsification method using polyether diol(N220),isophorone diisocyanate(IPDI),trimethylolpropane poly(ethylene glycol monomethyl ether)(N120),1,4-butanediol(BDO) and trimethylolpropane(TMP) as the main materials.The effects of the NCO/OH ratio on the emulsion and film properties of NWPU were explored.The experimental results show that the NWPU prepared at an NCO/OH ratio of 1.1 has good emulsion stability and easy film formation,and the resultant film was elastic,soft,and transparent.The sample was used for wool finishing and the application performance was evaluated.When the NWPU dosage reached 40 g·L^(-1),the fabric area felt shrinkage rate reduced from 8.97% to 4.75%,the pilling rating raised from grade 2-3 to grade 4,and the whiteness value only decreased by 3.87%.

Propagation Properties of Shock Waves in Polyurethane Foam based on Atomistic Simulations

Porous materials are widely used in the field of protection because of their excellent energy absorption characteristics.In this work,a series of polyurethane microscopic models are established and the effect of porosity on the shock waves is studied with classical molecular dynamics simulations.Firstly,shock Hugoniot relations for different porosities are obtained,which compare well with the experimental data.The pores collapse and form local stress wave,which results in the complex multi-wave structure of the shock wave.The microstructure analysis shows that the local stress increases and the local velocity decreases gradually during the process of pore collapse to complete compaction.Finally,it leads to stress relaxation and velocity homogenization.The shock stress peaks can be fitted with two exponential functions,and the amplitude of attenuation coefficient decreases with the increase of density.Besides,the pore collapse under shock or non-shock are discussed by the entropy increase rate of the system.The energy is dissipated mainly through the multiple interactions of the waves under shock.The energy is dissipated mainly by the friction between atoms under non-shock.

Carbon fiber confined mixed Ni-based crystal phases with interfacial charge redistribution induced by high bond polarity for electrochemical urea-assisted hydrogen generation

Interfacial electronic structure modulation of nickel-based electrocata-lysts is significant in boosting energy-conversion-relevant urea oxidation reaction(UOR).Herein,porous carbon nanofibers confined mixed Ni-based crystal phases of Ni_(2)P and NiF_(2) are developed via fluorination and phosphorization of Ni coated carbon nanofiber(Ni_(2)P/NiF_(2)/PCNF),which possess sufficient mesoporous and optimized Gibbs adsorption free energy by mixed phase-induced charge redistribution.This novel system further reduces the reaction energy barrier and improves the reaction activity by addressing the challenges of low intrinsic activity,difficulty in active site formation,and insufficient synergism.A considerably high current density of 254.29 mA cm^(-2) is reached at 1.54 V versus reversible hydrogen electrode on a glass carbon electrode,and the cell voltage requires 1.39 V to get 10 mA cm^(-2) in hydrogen generation,with very good stability,about 190 mV less than that of the traditional water electrolysis.The facile active phase formation and high charge transfer ability induced by asymmetric charge redistribution are found in the interface,where the urea molecules tend to bond with Ni atoms on the surface of heterojunction,and the rate-determining step is changed from CO_(2) desorption to the fourth H-atom deprotonation.The work reveals a novel catalyst system by interfacial charge redistribution induced by high bond polarity for energy-relevant catalysis reactions.

Synthesis of Organic-Inorganic Hybrid Aluminum Hypophosphite Microspheres Flame Retardant and Its Flame Retardant Research on Thermoplastic Polyurethane

Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.

Large-scale model testing of high-pressure grouting reinforcement for bedding slope with rapid-setting polyurethane

Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining walls,stabilizing piles,and anchors,are time-consuming and labor-and energy-intensive.This study proposes an innovative polymer grout method to improve the bearing capacity and reduce the displacement of bedding slopes.A series of large-scale model tests were carried out to verify the effectiveness of polymer grout in protecting bedding slopes.Specifically,load-displacement relationships and failure patterns were analyzed for different testing slopes with various dosages of polymer.Results show the great potential of polymer grout in improving bearing capacity,reducing settlement,and protecting slopes from being crushed under shearing.The polymer-treated slopes remained structurally intact,while the untreated slope exhibited considerable damage when subjected to loads surpassing the bearing capacity.It is also found that polymer-cemented soils concentrate around the injection pipe,forming a fan-shaped sheet-like structure.This study proves the improvement of polymer grouting for bedding slope treatment and will contribute to the development of a fast method to protect bedding slopes from landslides.

Urea breath test for Helicobacter pylori infection in adult dyspeptic patients: A meta-analysis of diagnostic test accuracy

BACKGROUND Helicobacter pylori(H.pylori)infection has been well-established as a significant risk factor for several gastrointestinal disorders.The urea breath test(UBT)has emerged as a leading non-invasive method for detecting H.pylori.Despite numerous studies confirming its substantial accuracy,the reliability of UBT results is often compromised by inherent limitations.These findings underscore the need for a rigorous statistical synthesis to clarify and reconcile the diagnostic accuracy of the UBT for the diagnosis of H.pylori infection.AIM To determine and compare the diagnostic accuracy of 13C-UBT and 14C-UBT for H.pylori infection in adult patients with dyspepsia.METHODS We conducted an independent search of the PubMed/MEDLINE,EMBASE,and Cochrane Central databases until April 2022.Our search included diagnostic accuracy studies that evaluated at least one of the index tests(^(13)C-UBT or ^(14)C-UBT)against a reference standard.We used the QUADAS-2 tool to assess the methodo-logical quality of the studies.We utilized the bivariate random-effects model to calculate sensitivity,specificity,positive and negative test likelihood ratios(LR+and LR-),as well as the diagnostic odds ratio(DOR),and their 95%confidence intervals.We conducted subgroup analyses based on urea dosing,time after urea administration,and assessment technique.To investigate a possible threshold effect,we conducted Spearman correlation analysis,and we generated summary receiver operating characteristic(SROC)curves to assess heterogeneity.Finally,we visually inspected a funnel plot and used Egger’s test to evaluate publication bias.endorsing both as reliable diagnostic tools in clinical practice.CONCLUSION In summary,our study has demonstrated that ^(13)C-UBT has been found to outperform the ^(14)C-UBT,making it the preferred diagnostic approach.Additionally,our results emphasize the significance of carefully considering urea dosage,assessment timing,and measurement techniques for both tests to enhance diagnostic precision.Nevertheless,it is crucial for researchers and clinicians to evaluate the strengths and limitations of our findings before implementing them in practice.

Continuous-flow electrosynthesis of urea and oxalic acid by CO_(2)-nitrate reduction and glycerol oxidation

Urea and oxalic acid are critical component in various chemical manufacturing industries.However,achieving simultaneous generation of urea and oxalic acid in a continuous-flow electrolyzer is a challenge.Herein,we report a continuous-flow electrolyzer equipped with 9-square centime-ter-effective area gas diffusion electrodes(GDE)which can simultaneously catalyze the glycerol oxidation reaction in the anode region and the reduction reaction of CO_(2) and nitrate in the cathode region,producing oxalic acid and urea at both the anode and cathode,respectively.The current density at low cell voltage(0.9 V)remained above 18.7 mA cm^(-2) for 10 consecutive electrolysis cycles(120 h in total),and the Faraday efficiency of oxalic acid(67.1%) and urea(70.9%)did not decay.Experimental and theoretical studies show that in terms of the formation of C-N bond at the cathode,Pd-sites can provide protons for the hydrogenation process of CO_(2) and NO_(3)^(-),Cu-sites can promote the generation of *COOH and Bi-sites can stabilize *COOH.In addition,in terms of glycerol oxidation,the introduction of Cu and Bi into Pd metallene promotes the oxidation of hydroxyl groups and the cleavage of C-C bond in glycerol molecules,respectively.

Efficient electrocatalytic urea synthesis from CO_(2)and nitrate over the scale-up produced FeNi alloy-decorated nanoporous carbon

Electrocatalytic urea synthesis provides a favorable strategy for conventional energy-consuming urea synthesis,but achieving large-scale catalyst synthesis with high catalytic efficiency remains challenging.Herein,we developed a simple method for the preparation of a series of FeNi-alloy-based catalysts,named FeNi@nC-T(n represents the content of nanoporous carbon as 1,3,5,7 or 9 g and T=900,950,1000 or 1100°C),for highly performed urea synthesis via NO_(3)−and CO_(2)co-reduction.The FeNi@7C-1000 achieved a high urea yield of 1041.33 mmol h^(−1)gFeNi^(−1)with a Faradaic efficiency of 15.56%at–1.2 V vs.RHE.Moreover,the scale-up synthesized FeNi@7C-950-S(over 140 g per batch)was achieved with its high catalytic performance and high stability maintained.Mechanism investigation illuminated that the Ni and Fe sites catalyze and stabilize the key*CO and*N intermediates and minimize the C–N coupling reaction barriers for highly efficient urea synthesis.

Generating highly active oxide-phosphide heterostructure through interfacial engineering to break the energy scaling relation toward urea-assisted natural seawater electrolysis

Urea-assisted natural seawater electrolysis is an emerging technology that is effective for grid-scale carbon-neutral hydrogen mass production yet challenging.Circumventing scaling relations is an effective strategy to break through the bottleneck of natural seawater splitting.Herein,by DFT calculation,we demonstrated that the interface boundaries between Ni_(2)P and MoO_(2) play an essential role in the selfrelaxation of the Ni-O interfacial bond,effectively modulating a coordination number of intermediates to control independently their adsorption-free energy,thus circumventing the adsorption-energy scaling relation.Following this conceptual model,a well-defined 3D F-doped Ni_(2)P-MoO_(2) heterostructure microrod array was rationally designed via an interfacial engineering strategy toward urea-assisted natural seawater electrolysis.As a result,the F-Ni_(2)P-MoO_(2) exhibits eminently active and durable bifunctional catalysts for both HER and OER in acid,alkaline,and alkaline sea water-based electrolytes.By in-situ analysis,we found that a thin amorphous layer of NiOOH,which is evolved from the Ni_(2)P during anodic reaction,is real catalytic active sites for the OER and UOR processes.Remarkable,such electrode-assembled urea-assisted natural seawater electrolyzer requires low voltages of 1.29 and 1.75 V to drive 10 and600 mA cm^(-2)and demonstrates superior durability by operating continuously for 100 h at 100 mA cm^(-2),beyond commercial Pt/C||RuO_(2) and most previous reports.

Integrated assessment of yield,nitrogen use efficiency and ecosystem economic benefits of use of controlled-release and common urea in ratoon rice production

Controlled-release urea(CRU)is commonly used to improve the crop yield and nitrogen use efficiency(NUE).However,few studies have investigated the effects of CRU in the ratoon rice system.Ratoon rice is the practice of obtaining a second harvest from tillers originating from the stubble of the previously harvested main crop.In this study,a 2-year field experiment using a randomized complete block design was conducted to determine the effects of CRU on the yield,NUE,and economic benefits of ratoon rice,including the main crop,to provide a theoretical basis for fertilization of ratoon rice.The experiment included four treatments:(i)no N fertilizer(CK);(ii)traditional practice with 5 applications of urea applied at different crop growth stages by surface broadcasting(FFP);(iii)one-time basal application of CRU(BF1);and(iv)one-time basal application of CRU combined with common urea(BF2).The BF1 and BF2 treatments significantly increased the main crop yield by 17.47 and 15.99%in 2019,and by 17.91 and 16.44%in 2020,respectively,compared with FFP treatment.The BF2 treatment achieved similar yield of the ratoon crop to the FFP treatment,whereas the BF1 treatment significantly increased the yield of the ratoon crop by 14.81%in 2019 and 12.21%in 2020 compared with the FFP treatment.The BF1 and BF2 treatments significantly improved the 2-year apparent N recovery efficiency,agronomic NUE,and partial factor productivity of applied N by 11.47-16.66,27.31-44.49,and 9.23-15.60%,respectively,compared with FFP treatment.The BF1 and BF2 treatments reduced the chalky rice rate and chalkiness of main and ratoon crops relative to the FFP treatment.Furthermore,emergy analysis showed that the production efficiency of the BF treatments was higher than that of the FFP treatment.The BF treatments reduced labor input due to reduced fertilization times and improved the economic benefits of ratoon rice.Compared with the FFP treatment,the BF1 and BF2 treatments increased the net income by 14.21-16.87 and 23.76-25.96%,respectively.Overall,the one-time blending use of CRU and common urea should be encouraged to achieve high yield,high nitrogen use efficiency,and good quality of ratoon rice,which has low labor input and low apparent N loss.

Preparation and Tribological Properties of Onion-like Carbon/Waterborne Polyurethane Coatings

Rice husk powder was used as a carbon source in a high-temperature carbonization reaction for the production of rice husk ash(RHA).Under the catalysis of ferric nitrate,onion-like carbon(OLC)nanomaterial with a particle size of approximately 200 nm was successfully prepared and incorporated into waterborne polyurethane(WPU).The tribological properties of the coatings were determined using a controlled-atmosphere tribometer(WMT-2E)under dry-friction conditions.Following the friction test,the friction mechanism was investigated by characterizing the abrasive spot surfaces of the test samples using 3D laser microscopy and scanning electron microscopy/energy dispersive spectrometer.The final results demonstrated that the thermal stability of WPU composite coatings containing various concentrations of OLC nanoparticles was significantly enhanced,binding forces between coatings and steel sheets increased,and hardness improved compared to pure WPU coatings.Tribological tests revealed a notable enhancement in the anti-wear properties of WPU coatings due to the presence of OLC particles.Specifically,the wear rate of the 1.5%OLC/WPU coating was reduced by 45.3%.The coating’s anti-wear mechanism was attributed to the improvement in the mechanical properties of WPU due to OLC,as well as OLC’s participation in the formation of a transfer film under induced friction,which protected the matrix.

Evaluation of urea breath test as a diagnostic tool for Helicobacter pylori infection in adult dyspeptic patients

In this editorial,we discuss the article in the World Journal of Gastroenterology.The article conducts a meta-analysis of the diagnostic accuracy of the urea breath test(UBT),a non-invasive method for detecting Helicobacter pylori(H.pylori)infection in humans.It is based on radionuclide-labeled urea.Various methods,both invasive and non-invasive,are available for diagnosing H.pylori infection,inclu-ding endoscopy with biopsy,serology for immunoglobulin titers,stool antigen analysis,and UBT.Several guidelines recommend UBTs as the primary choice for diagnosing H.pylori infection and for reexamining after eradication therapy.It is used to be the first choice non-invasive test due to their high accuracy,specificity,rapid results,and simplicity.Moreover,its performance remains unaffected by the distribution of H.pylori in the stomach,allowing a high flow of patients to be tested.Despite its widespread use,the performance characteristics of UBT have been inconsistently described and remain incompletely defined.There are two UBTs available with Food and Drug Administration approval:The 13C and 14C tests.Both tests are affordable and can provide real-time results.Physicians may prefer the 13C test because it is non-radioactive,compared to 14C which uses a radioactive isotope,especially in young children and pregnant women.Although there was heterogeneity among the studies regarding the diagnostic accuracy of both UBTs,13C-UBT consistently outperforms the 14C-UBT.This makes the 13C-UBT the preferred diagnostic approach.Furthermore,the provided findings of the meta-analysis emphasize the significance of precise considerations when choosing urea dosage,assessment timing,and measurement techniques for both the 13C-UBT and 14C-UBT,to enhance diagnostic precision.