Three‑dimensional numerical simulation of dynamic strength and failure mode of a rock mass with cross joints

To study the dynamic mechanical properties and failure characteristics of intersecting jointed rock masses with different joint distributions under confining pressure,considering the cross angleαand joint persistence ratioη,a numerical model of the biaxial Hopkinson bar test system was established using the finite element method–discrete-element model coupling method.The validity of the model was verified by comparing and analyzing it in conjunction with laboratory test results.Dynamics-static combined impact tests were conducted on specimens under various conditions to investigate the strength characteristics and patterns of crack initiation and expansion.The study revealed the predominant factors influencing intersecting joints with different angles and penetrations under impact loading.The results show that the peak stress of the specimens decreases first and then increases with the increase of the cross angle.Whenα<60°,regardless of the value ofη,the dynamic stress of the specimens is controlled by the main joint.Whenα≥60°,the peak stress borne by the specimens decreases with increasingη.Whenα<60°,the initiation and propagation of cracks in the cross-jointed specimens are mainly controlled by the main joint,and the final failure surface of the specimens is composed of the main joint and wing cracks.Whenα≥60°orη≥0.67,the secondary joint guides the expansion of the wing cracks,and multiple failure surfaces composed of main and secondary joints,wing cracks,and co-planar cracks are formed.Increasing lateral confinement significantly increases the dynamic peak stress able to be borne by the specimens.Under triaxial conditions,the degree of failure of the intersecting jointed specimens is much lower than that under uniaxial and biaxial conditions.

Synthesis of Reprocessable Lignin-based Non-isocyanate Poly(imine-hydroxyurethane)s Networks

In this study,an environmentally friendly and non-toxic route to synthesize lignin-based non-isocyanate poly(imine-hydroxyurethane)s networks was explored.Specifically,the NH_(2)-terminated polyhydroxyurethanes(NPHUs)prepolymer was first synthesized from bis(6-membered cyclic carbonate)(BCC)and diamine via the ring-opening reaction.Subsequently,the corresponding ligninbased non-isocyanate polyurethanes(NIPUs)with tunable properties were synthesized from NPHUs and levulinate lignin derivatives containing ketone groups via the Schiff base reaction.The structural,mechanical,and thermal properties of NIPUs with different stoichiometric feed ratios of BCC and levulinate lignin were characterized by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance(NMR),differential scanning calorimetry(DSC),dynamic mechanical analysis(DMA),and thermogravimetric analysis(TGA).The results indicated that the tensile strength,Young's modulus,toughness,storage modulus,glass transition temperature,and thermal stability of lignin-based NIPUs gradually increased with increasing lignin content,and the highest Young's modulus of 41.1 MPa was obtained when lignin content reached 45.53%.With good reprocessing properties,this synthetic framework of ligninbased NIPUs also provides sustainable non-isocyanate-based substitutions to traditional polyurethane networks.

Preparation and Applications of Soybean Residue CNF Films

In this study, soybean residues were treated with HCl and soybean residue cellulose was extracted, which was used to prepare cellulose nanofiber (CNF) using the high-pressure homogenization method. The maximum yield of CNF, the reaction temperature, reaction time, and HCl concentration were optimized. The optimum HCl concentration for acid treatment was 6%, the reaction time was 60 min, the reaction temperature was 80℃, and the maximum yield of soybean residue cellulose was 78.8%. The different CNF films were then prepared;the color, mechanical property, and light transmittance of the CNF films were studied. Compared to the properties of the CNF film prepared with the soybean residue cellulose by high-pressure homogenization 15 times (HGT-15 film), the mechanical properties of the CNF film with soybean residue cellulose by decolorizing treatment decreased, but the light transmittance increased. The film prepared by adding HGT- 15 CNF to whey protein was investigated for its mechanical property, light transmittance, and solubility. Unlike the pure whey protein film, addition of 2.0% CNF to the whey protein enhanced the mechanical property and water vapor transmission rate (WVT) of the film. With the increase in CNF content, the solubility of the whey protein film decreased, and then stabilized.

Synthesis of Lignin-based Nonisocyanate Poly(imine-hydroxyurethane)s Networks.Part II:Self-healing,Reprocessing,and Degradation

This study provides a comprehensive understanding of the polymeric properties of lignin-based non-isocyanate poly(iminehydroxyurethane)s(LNIPUs).The properties of the LNIPUs are affected by changes in the stoichiometric feed ratios of the bis(6-membered cyclic carbonate)(BCC)and levulinate enzymatic hydrolysis lignin(LEHL).The results showed that the LNIPUs exhibited a short relaxation time and excellent thermal repair and degradation properties.With a change in the LEHL content in the LNIPUs to 45.53%,a relaxation time of only 9 s was achieved,and the thermal repair rate of the scratches reached 93%.Furthermore,the tensile strength of the LNIPUs decreased with an increase in the LEHL content after two hot-pressing processes,while a higher than 75% tensile strength was maintained after the second hot-pressing treatment.The LNIPUs exhibited thermoresponsive shape memory property with deformation and shape fixing at 80℃.In addition,the as-synthesized LNIPUs were soluble in ethylene glycol in the absence of any organic solvents.This work demonstrates the synthesis of LNIPUs with self-healing,reprocessing,shape memory,and degradation properties.

The Results Observation on Adjuvant Chemotherapy with Microwave Hyperthermia and Stereotactic Radiotherapy in Retreated Elderly Patients with Advanced (III/IV Stage) Lung Cancer

Objective: To evaluate the significance of adjuvant chemotherapy and radiotherapy (Gamma-knife) in the elderly patients with retreated advance lung cancer. Methods 83 patients (age 50 to 81 years) with retreating advanced (III/IV stage) lung cancer were divided into three groups according to patients received treating by different methods. The cases were treated by synchronous chemo-radiotherapy (A group), sequentially chemo-radiotherapy (B group) and continuous systematized chemotherapy alone (C group). The systemic 3-dimensional orientation apparatus was used in radiotherapy. The chemotherapy regimen in combined radiotherapy was given by common first line regimen on lung cancer. The regimen of chemotherapy combated with whole body hyperthermia by using micro-wave on abodeman about 2 or 3 line was used in C group only. Results: The overall responses rates (RR) of A, B and C groups were 17.1%, 11.5% and 31.8%, but it was non-significance difference (P > 0.05). Overall responses rates (RR) of III and IV stage groups were 18.2% and 20.0%. The average overall survival time (OS) and median survival time (MST) of the patients treated by chemotherapy (C group) were highest about 14.2 and 9.3 months (respectively at A group 6.7 and 6.0 months. P < 0.01), in which B group was longer than A group (P < 0.05), and 95.5% CI value was not overlap. The total survival time of postoperative patients was longer in the various groups by different treated than that in non-operations. Conclusion: The rates (RR) of III and IV stage groups were non-significance difference. The higher of ORR, OS and MST in a few patients of re-treated advanced lung cancer was presented in case with treated by continuous system chemotherapy. There were survival superiority in initial postoperative patients groups by different treated. It is a profitable and effect treatment that the pure reasonable systemic chemotherapy was used for elderly case with advanced retreated lung cancer.

High-performance SSZ-13 membranes prepared using ball-milled nanosized seeds for carbon dioxide and nitrogen separations from methane

SSZ-13 membranes with high separation performances were prepared using ball-milled nanosized seeds by once hydrothermal synthesis.Separation performances of SSZ-13 membranes in CO2/CH4 and N2/CH4 mixtures were enhanced after synthesis modification.Single-gas permeances of CO2,N2 and CH4 and ideal selectivities were recorded through SSZ-13 membranes.The effects of temperature,pressure,feed flow rate and humidity on separation performance of the membranes were discussed.Three membranes prepared after synthesis modifications had an average CO2 permeance of 1.16×10-6 mol·(m2·s·Pa)-1(equal to 3554 GPU)with an average CO2/CH4 selectivity of 213 in a 50 vol%/50 vol%CO2/CH4 mixture.It suggests that membrane synthesis has a good reproducible.The membrane also displayed a N2 permeance of 1.07×10-7 mol·(m2·s·Pa)-1(equal to 320 GPU)with a N2/CH4 selectivity of 13 for a 50 vol%/50 vol%N2/CH4 mixture.SSZ-13 membrane displayed stable and good separation performance in the wet CO2/CH4 mixture for a long test period over 100 h at 348 K.The current SSZ-13 membranes show great potentials for the simultaneous removals of CO2 and N2 in natural gas purification as a facile process suitable for industrial application.

Preparation and Properties of Nanocellulose/Sodium Alginate Composite Hydrogel

Cellulose nanofiber(CNF)was isolated from Okara using deep eutectic solvent(DES)with high-speed stirring.The composite hydrogels obtained by using different proportions of CNF and sodium alginate(SA)had different properties.The CNF/SA composite hydrogels were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy and tested for compression properties,rheological properties,water content,and swelling degree.Physical crosslinking between SA and Ca^(2+),and different degrees of hydrogen bond formation between SA and CNF were observed.The CNF/SA composite hydrogel have great potential as reinforcements in eco-friendly composite hydrogels for diverse applications.

Effect of High Pressure Homogenization Treatment on Structure and Properties of Soybean Residue Cellulose Nanofibers

To reduce the adverse effects of non-cellulose materials on subsequent homogenization,the effects of a high-pressure homogenization treatment on the structure and properties of cellulose nanofibers(CNF)prepared by acid treatment of soybean residue were studied.The effects of the number of homogenization step on the microfibrillation degree,crystalline structure and mechanical properties of the soybean residue were analyzed by SEM,FT-IR,XRD,TG and DTG.The results showed that an increase in the number of homogenization steps led to an increase in the degree of microfibrillation,a more uniform distribution of the CNF diameter,and an increase in the crystallinity of CNF.However,but when the number of homogenization steps exceeded 15,the rate of change decreased,and the crystallinity of CNF decreased.As the number of homogenization steps increased,the average degree of polymerization and average molecular weight of CNF decreased continuously,and after 15 homogenization steps,their rate of change also decreased.Therefore,15 steps of high-pressure homogenization represented a suitable number of steps to prepare the soybean residue CNF with an average diameter of 15 nm.

Solvatochromic Probe Based on Nanocellulose Membrane Coated with Zn-terpyridine Complex in a Layer-by-Layer Manner

Solvatochromic materials have recently attracted increasing attention owing to their great significance in the security and sensor fields.In this study,ultrafast explicit and implicit information was collected regarding a fluorescent nanocellulose membrane produced from nanocellulose membranes coated with a Zn-terpyridine complex(Zn-tpy)in a layer-by-layer manner.The fluorescent emissions of the nanocellulose membrane changed from yellow(CIE:x=0.37,y=0.45)to green(CIE:x=0.32,y=0.47)under a dichloromethane environment and 365-nm irradiation.Due to the ease of dichloromethane volatilization,fluorescent emissions quickly returned to the original state.These solvatochromic nanocellulose membranes,with ultrafast explicit and implicit information,exhibited valuable application prospects in anti-counterfeiting techniques.

固定翼无人机飞行参数评估模型与实验

固定翼无人机飞行过程中,为减小模型参数的不确定性和外界扰动对控制器的影响,本文提出了一种飞行参数估计模型,在STM32上通过编程实现了该模型,通过飞行试验验证了该飞行参数估计模型的可行性。

Application of immune checkpoint targets in the anti-tumor novel drugs and traditional Chinese medicine development

Immune checkpoints are the crucial regulators of immune system and play essential roles in maintaining self-tolerance,preventing autoimmune responses,and minimizing tissue damage by regulating the duration and intensity of the immune response.Furthermore,immune checkpoints are usually overexpressed in cancer cells or noninvasive cells in tumor tissues and are capable of suppressing the antitumor response.Based on substantial physiological analyses as well as preclinical and clinical studies,checkpoint molecules have been evaluated as potential therapeutic targets for the treatment of multiple types of cancers.In the last few years,extensive evidence has supported the immunoregulatory effects of traditional Chinese medicines(TCMs).The main advantage of TCMs and natural medicine is that they usually contain multiple active components,which can act on multiple targets at the same time,resulting in additive or synergistic effects.The strong immune regulation function of traditional Chinese medicine on immune checkpoints has also been of great interest.For example,Astragalus membranaceus polysaccharides can induce anti-PD-1 antibody responses in animals,and these antibodies can overcome the exhaustion of immune cells under tumor immune evasion.Furthermore,many other TCM molecules could also be novel and effective drug candidates for the treatment of cancers.Therefore,it is essential to assess the application of immune checkpoints in the development of new drugs and TCMs.In this review,we focus on research progress in the field of immune checkpoints based on three topics:(1)immune checkpoint targets and pathways,(2)development of novel immune checkpoint-based drugs,and(3)application of immune checkpoints in the development of TCMs.

Bimetallic Ni-Mo nitride@C_(3)N_(4) for highly active and stable water catalysis

Non-noble metal electrocatalysts for water cracking have excellent pro-spects for development of sustainable and clean energy.Highly efficient electrocatalysts for the oxygen evolution reaction(OER)are very important for various energy storage and conversion systems such as water splitting devices and metal-air batteries.This study prepared a NiMo4@C_(3)N_(4) catalyst for OER and hydrogen evolution reaction(HER)by simple methods.The catalyst exhibited an excellent OER activity based on the response at a suitable temperature.To drive a current density of 10 mA-cm^(-2) for OER and HER,the overpotentials required for NiMo4@C_(3)N_(4)-800(prepared at 800℃)were 259 and 118 mV,respectively.A two-electrode system using NiMo4@C_(3)N_(4)-800 needed a very low cell potential of 1.572 V to reach a current density of 10 mA-cm^(-2).In addition,this catalyst showed excellent durability after long-term tests.It was seen to have good catalytic activity and broad application prospects.

Experimental investigation on dynamic mechanical properties of sandy clay treated with alkali-activated metakaolin cement and discrete polypropylene fibers

The dynamic mechanical properties and dynamic energy absorption capacity of marine sandy clay,which was stabilized by cement with partial substitution of alkali-activated metakaolin(AAMK)and discrete polypropylene fibers,were experimentally investigated at strain rates of 80-280 s^(-1).The AAMK,as partial replacement of cement,is eco-friendly and economical,and polypropylene fibers with corrosion resistance can withstand severe environmental conditions.Dynamic mechanical properties of 16 different mix ratios were experimentally examined via split Hopkinson compression pressure bar(SHPB)tests.Typical macroscopic post-impact fragment patterns Ⅰ and Ⅱ were observed in dynamic stress-strain curves and macroscopic fragmentations.The results confirmed an obvious enhancement in the dynamic compressive strength and energy absorption density due to the use of cement with partial substitution of AAMK and the addition of polypropylene fibers and sand.Based on scanning electron microscopy(SEM)tests and nuclear magnetic resonance(NMR)tests,cemented sandy clay specimens treated with 0.2%fiber contents or higher exhibited a denser network of soil particles with hydration products.The connection mechanism and typical interface between fiber-sand-hydrate-sandy clay particles were observed via SEM tests.Furthermore,an optimal mix ratio was proposed to satisfy the demands of high dynamic mechanical properties,energy absorption capacity,and economic and environmental constraints.The optimal mix ratio corresponded to 0.2% fiber content or higher and sand content of up to 16%.Additionally,it was observed that the dynamic compressive strength of samples with 0.1% fibers or less deteriorated.Based on absorption energy density and failure modes analysis,the fiber content should be higher than or equal to 0.2% to effectively reduce the degree of fragmentation and increase the size of fragments.

Influence of the spatial distribution of underground tunnel group on its blasting vibration response

The spatial distribution of underground tunnels is significant to the stress redistribution in the surrounding rock masses and blast wave propagation.The field blasting tests were first carried out to study the propagation of blast-induced seismic waves through under-ground tunnels of the Xiluodu Hydropower Station in China.The results show that the peak horizontal particle vibration velocity can be used as a safety criterion for underground tunnels.The effects of in situ stresses and spatial distributions of the tunnel group on the vibra-tion velocities distribution is afterward investigated by numerical simulation.The results show that there is a significant amplification of the blasting vibrations in the adjacent tunnels,which depends on their vertical positions during the excavation of a tunnel.The peak vibration velocity decreases as the lateral separation between tunnels increases.When the separation between the tunnels exceeds the width of three tunnels,the impact of the blast waves on each part of the adjacent tunnel tends to be stable on the whole.In terms of the size of the tunnel,the blasting vibration velocity in the upper part of the straight wall on the front-blast side increases as the width increases(and then levels off),while the blasting vibration velocity in the lower part decreases as the width increases(and then levels off).Finally,a generalized formula of blasting vibration velocity considering the spatial distribution is established,which can well predict the vibration velocity of particles in underground tunnels.

Single-cell RNA landscape of the special fiber initiation process in Bombax ceiba

As a new source of natural fibers,the Bombax ceiba tree can provide thin,light,extremely soft and warm fiber material for the textile industry.Natural fibers are an ideal model system for studying cell growth and differentiation,but the molecular mechanisms that regulate fiber initiation are not fully understood.In B.ceiba,we found that fiber cells differentiate from the epidermis of the inner ovary wall.Each initiated cell then divides into a cluster of fiber cells that eventually develop into mature fibers,a process very different from the classical fiber initiation process of cotton.We used high-throughput single-cell RNA sequencing(scRNA-seq)to examine the special characteristics of fiber initiation in B.ceiba.A total of 15567 high-quality cells were identified from the inner wall of the B.ceiba ovary,and 347 potential marker genes for fiber initiation cell types were identified.Two major cell types,initiated fiber cells and epidermal cells,were identified and verified by RNA in situ hybridization.A developmental trajectory analysis was used to reconstruct the process of fiber cell differentiation in B.ceiba.Comparative analysis of scRNAseq data from B.ceiba and cotton(Gossypium hirsutum)confirmed that the additional cell division process in B.ceiba is a novel species-specific mechanismfor fiber cell development.Candidate genes and key regulators that may contribute to fiber cell differentiation and division in B.ceiba were identified.This work reveals gene expression signatures during B.ceiba fiber initiation at a single-cell resolution,providing a new strategy and viewpoint for investigation of natural fiber cell differentiation and development.

Lanthanum:A novel inducer for enhancement of fungal laccase production by Shiraia bambusicola

Fungal laccases are industrially important inducible enzymes extensively used in the delignification of lignocellulosics,detoxification of environmental wastes and decolorization of textile dyes.The discovery of new inducers is crucial for laccase productivity by filamentous fungi.In this study,a novel laccase-producing strain S8 from a bambusicolous fungus Shiraia bambusicola was identified by using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate)as laccase secretion indicator and native polyacrylamide gel electrophoresis.The corresponding full-length cDNA of laccase was cloned and characterized.The effect of lanthanum(LaCl_(3))on extracellular laccase activity was tested at the concentration from 0.2 to 2.0 g/L and at different addition time(day 1-4)in the mycelium culture.In the presence of 1.0 g/L La^(3+) at the beginning of the mycelium cultures,the highest laccase activity(2.7×10^(4) U/L)is reached after 10 days of cultivation,about tenfold higher compared with non-induced cultures.La^(3+) is shown to be a very strong inducer for fungal laccase activity with no inhibitory effect on fungal growth at the optimized concentration.In vivo,La^(3+) added to the mycelium culture not only promotes a continuous and high expression of laccase gene(lcc1),but also induces a rapid generation of signaling molecules including reactive oxygen species(ROS)and nitric oxygen(NO).Both the NO donor sodium nitroprusside(SNP)and exogenous hydrogen peroxide(H_(2)O_(2))potentiate La^(3+)-induced laccase activity and increase membrane permeability of hyphal cells.Moreover,the scavengers such as 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide(cPTIO)for NO and vitamin C for ROS suppress the induction.These results suggest that these signals can mediate La^(3+)-induced laccase biosynthesis and its secretion.Our study provides a basis for understanding the induction mechanism of La^(3+) on laccase and a practical strategy for enhanced fungal laccase production.

Fe-doped NiCo_(2)O_(4)hollow hierarchical sphere as an efficient electrocatalyst for oxygen evolution reaction

We prepared porous Fe-doped nickel cobaltate(Fe-NiCo_(2)O_(4))hollow hierarchical nanospheres through a facile self-templated synthetic strategy.Due to the porous hollow structure and composition,the Fe-NiCo_(2)O_(4)presented vastly superior electrocatalytic activity for the oxygen evolution reaction(OER),compared with NiCo_(2)O_(4)and the majority of other OER catalysts.With an aim of stimulating a current density of 10 mA$cm-2,the Fe-NiCo_(2)O_(4)catalyst needs an overpotential of 210 mV,which is on a par with the general properties of commercial IrO2.In addition,the Fe-NiCo_(2)O_(4)catalyst performed stably in long-term testing.The excellent activity and long-term stability showed that such catalysts have great promise for widespread application in the field of water splitting.

Pediatric cancer surveillance in China:A hospital-based introduction

Background In recent years,increasing numbers of families have been affected by childhood cancer.According to data from the International Agency for Research on Cancer(IARC)of the World Health Organization,approximately 279000 new cases of cancer were predicted in children and adolescents aged 0–19 years worldwide in 2020.The global incidence of childhood cancer is 10.9 per 100000(global standard rate)and the mortality rate is 4.2 per 100000.1 According to data from the China National Cancer Center,the incidences of cancer in 2017 were 9.9 per 100000 in children aged 0–14 years and 11.5 per 100000 in adolescents aged 15–19 years.2 There are estimated to be approximately 22000 new cases of childhood cancer in China each year,and the incidence of malignant tumors in children aged 0–14 years has increased by 2.5%annually in the past decade.