Mechanical behaviours of sandstone containing intersecting fissures under uniaxial compression

Predicting rock cracking is important for assessing the stability of underground engineering.The effects of the intersecting angle a and the distribution orientation angleβof intersecting fissures on the uniaxial compressive strength and the failure characteristics of sandstone containing intersecting fissures are investigated through laboratory experiments and two-dimensional particle flow code(PFC2D).The relationship between the mechanical properties of sandstone and the intersecting angle a and the distribution orientation angleβis analysed.Crack initiation forms and the final failure modes are then categorised and determined via empirical methods.In addition,the cracking processes of intersecting fissures with different a andβvalues are discussed.The results show that variations in the peak stress,peak strain,average modulus,and crack initiation stress of sandstone containing intersecting fissures show a“moth”shape in the space of the a-β-mechanical parameters.Two crack initiation forms are identified:inner tip cracking(usually accompanied by one outer tip cracking)and only outer tips cracking.Two failure modes are observed:(1)the main fracture planes are created at the inner tip and one outer tip,and(2)the main fracture planes are formed at the two outer tips.Two main crack evolution processes of sandstone containing intersecting fissures under uniaxial compression are found.Approaches for quickly determining the crack initiation form and the failure mode are proposed.The combination of the determination equations for the crack initiation form and the failure mode can be used to predict the crack evolution.The approach for determining the crack evolution processes is hence proposed with acceptable precision.

Small-scale alpine topography at low latitudes and high altitudes:refuge areas of the genus Chrysanthemum and its allies

Cultivated chrysanthemum(Chrysanthemum morifolium Ramat.)is an economically important ornamental plant species grown worldwide.However,the origin of the genus Chrysanthemum remains unclear.This study was conducted in the Hengduan Mountains,Yunnan Province.We took advantage of a special geographic region where the southernmost species of Ajania and the highest altitude population of Chrysanthemum indicum coexist to investigate their evolutionary origins.Diversity analysis of 9 populations of 5 species that came from 3 genera was carried out based on morphological traits and SRAP markers.Furthermore,topographical and ecological analyses and surveys of the vegetation communities in the plots were carried out for correlation analysis,and past data were used to reconstruct the ancient topography and vegetation to estimate the migration path and divergence time.We found that Chrysanthemum and Ajania were closely related based on the smooth transition states among marginal female florets and their common pollination system.The genetic relationship between Phaeostigma and Chrysanthemum was relatively distant,and Ajania was between them.Low light intensity and relatively humid habitats may be driving the elongation and evolution of marginal female florets.We found that Chrysanthemum and related genera were largely restricted to stony topographies at an altitude of~3000 m.a.s.l.and in specialized alpine coniferous(Pinus)and broadleaved(Quercus)mixed forest marginal communities.These stony topographies have become ecological islands of refuge for these species in the current interglacial period.The Hengduan Mountains play a key role in the evolution,divergence,and survival of Chrysanthemum and its allies.

Theoretical framework construction on care complexity in Chinese hospitals: A grounded theory study

Objectives: This study aims to construct a theoretical framework to analyze risk factors and explore hospital nurses' perspectives on care complexity.Methods: The grounded theory method was adopted,and semi-structured in-depth interviews regarding the understanding of care complexity were conducted among the participants,including 31 nurses and nine doctors.In addition,data were coded and strictly analyzed in accordance with the coding strategy and requirements of grounded theory.Results: Our study reveals three factors that are closely related to care complexity,namely,(1) patient factors,including patients' condition,age,self-care abilities,compliance,social support systems,psy chological conditions,expectations,and requirements;(2) nursing staff factors,including work experiences,education,knowledge and operational skills of caring,and communication skills;and (3) organization and equipment factors,including nursing workforce,nursing workload,support from multidisciplinary teams and ancillary departments,and the conditions of medical and hospital services.Conclusions: This study defines care complexity on the basis of its factors.Care complexity refers to the difficulty of nursing tasks during patient care plan implementation,which are affected by patients,nurses,and other factors in nursing and multisectoral,multidisciplinary cooperation.The framework can be beneficial for nursing education and for the improvement of the quality and efficiency of clinical nursing practice.

Interlayer and doping engineering in partially graphitic hollow carbon nanospheres for fast sodium and potassium storage

Constructing anodes with fast ions/electrons transfer paths is an effective strategy to achieve high-performance sodium ion batteries(SIBs)/potassium ion batteries(PIBs). Amorphous carbon is a promising candidate anode for SIBs/PIBs owing to its disordered carbon layers, abundant defects/pores, and lowcost resources. However, the larger radius of Na^(+)/K^(+) leading to depressed kinetics and poor cycling performance, impeding their further applications. Herein, we propose an efficient strategy to construct of nitrogen, sulfur co-doped hollow carbon nanospheres(NS-HCS) involving an in situ growth of polydopamine on nano-Ni(OH)2template with subsequent sulfur doping process. During the formation process, the produced Ni nanospheres play as the hard template and catalyst for the formation of hollow carbon nanosphere with partially graphite microcrystalline structure, while the sulfur doping process can enlarge the interlayer space and create more defects on the surface of carbon nanospheres, thus synchronous improve the Na^(+)/K^(+) insertion and adsorption ability in NS-HCS. With the synergistic control of the enlarged interlayer spacing, high content of pyridinic N/pyrrolic N and graphitization, a hybrid storage mechanism facilitates the transport kinetics and endows the NS-HCS electrode with high capacities and good cycling stability in SIBs and PIB. Benefit from the multiple effects, NS-HCS exhibits the improved capacity of 274.8 m Ah/g at 0.1 A/g and excellent cycling stability of 149.5 m Ah/g after 5000 cycles at2.5A/g in SIBs, as well as good potassium ion storage behavior with a high capacity retention of 76.5%after 700 cycles at 1.0 A/g, demonstrating the potential applications of NS-HCS for high-performance SIBs and PIBs.

Conjugated Polymers for Combatting Antimicrobial Resistance

Antimicrobial resistance(AMR)is one of the major challenges in pathogenic infections,which endangers human health and brings devastating public health threats.Therefore,developing new materials to reduce the over-reliance on antibiotics or to replace antibiotics is in great need to solve this problem.Conjugated polymers(CPs)with excellent light-harvesting properties and good biocompatibility are ideal candidate materials for combat-ting AMR through photodynamic antimicrobial therapy(PACT)by sensitizing oxygen and photothermal therapy(PTT)by light to heat conversion.Sig-nificant works of CPs-based antimicrobial approaches have been reported in recent years.Herein,we summarize the types of CPs-based antimicrobial materials,illustrate their antimicrobial mechanisms,and discuss their applications in combating AMR mainly by PACT or antimicrobial PTT.In addi-tion,we proposed some other antimicrobial treatment strategies based on CPs,hoping to provide inspiring insight for overcoming AMR.

Strategies for Inhibition and Disaggregation of Amyloid-β Fibrillation

Comprehensive Summary Amyloid-β protein(Aβ)is a fatal cause of Alzheimer's disease,which can trigger a series of cytotoxicity by the abnormal aggregation of Aβ in human brain.The strategies for inhibition and disaggregation of Aβ fibrillation are mostly based on the interaction between monomers,oligomers,fibrils,and materials.