聚乳酸熔喷法非织造材料的应用及改性研究进展

为促进聚乳酸熔喷法非织造材料在医疗卫生、过滤分离和环境保护等领域的功能性应用,进而缓解传统石油基熔喷法非织造材料所带来的资源短缺与环境污染问题,文中对聚乳酸熔喷法非织造材料的成型、应用及改性研究进行了梳理,分析了聚乳酸熔喷法非织造材料的改性方法,并总结了聚乳酸熔喷法非织造材料的增韧改性、增塑改性、耐热改性及其他功能性改性。最后指出增强聚乳酸熔喷法非织造材料的功能性是其应用推广的必要前提,通过对聚乳酸熔喷法非织造材料的改性研究分析,为后续聚乳酸熔喷法非织造材料的研究与发展提供理论支持。

CEPC Technical Design Report

The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.

Design and simulation of a novel 4H-SiC LGAD timing device

Purpose Silicon-based fast timing detectors have been widely used in high-energy physics,nuclear physics,space exploration and other fields in recent years.However,silicon detectors often require complex low-temperature systems when operating in irradiation environment,and their detection performance decreases with the increase in the irradiation dose.Compared with silicon,silicon carbide(SiC)has a wider band gap,higher atomic displacement energy,saturated electron drift velocity and thermal conductivity.Simultaneously,the low-gain avalanche detector avoids cross talk and high noise from high multiplication due to its moderate gain,and thus can maintain a high detector signal without increasing noise.Aim Thus,the 4H-SiC particle detector,especially the low-gain avalanche detector,has the potential to detect the minimal ionizing particles under extreme irradiation and high-temperature environments.Method In this work,the emphasis was placed on the design of a 4H-SiC low-gain avalanche detector(LGAD),especially the epitaxial structure and technical process which play main roles.In addition,a simulation tool—RASER(RAdiation SEmiconductoR)—was developed to simulate the performances including the electrical properties and time resolution of the 4H-SiC LGAD we proposed.Conclusion The working voltage and gain effectiveness of the LGAD were verified by the simulation of electrical performances.The time resolution of the LGAD is(35.0±0.2)ps under the electrical field of−800 V,which is better than that of the 4H-SiC PIN detector.

Phosphorus does not alleviate the negative effect of nitrogen enrichment on legume performance in an alpine grassland

Aims Nitrogen(N)-fixing legumes,despite being highly phosphorus(P)-demanding,constitute an important plant functional group and play key roles in N-poor ecosystems such as alpine grasslands.However,legume performance,including biomass,abundance and species richness,is expected to change,because anthropogenic activities have drastically increased soil N and P availability world-wide.We conducted a field experiment to assess the effects of N and P addition,alone and in combination,on legume performance in an alpine grassland,and identified and clarified the mechanisms underlying these changes.Methods A three year field experiment of N addition(10 g N m−2 year−1),P addition(5 g P m−2 year−1),and N+P combined addition(both N and P,same amounts as solo treatments)was conducted in an alpine grassland on the tibetan Plateau in china from 2011 to 2013.Effects of nutrient addition were assessed at the community level(above-ground net primary production(ANPP),height and light intensity),functional group level(biomass,species richness,relative height,relative coverage and relative density of legumes)and species level(foliar N,P concentration of two legumes).Important findings Overall,adding N alone significantly increased ANPP by 20.82%,but adding P alone did not;whereas,addition of N and P together resulted in a large increase in ANPP(+37.03%)than addition of either alone,indicating potential co-limitation of alpine grasslands.In contrast,adding P alone significantly promoted legume perfor-mance as measured by 65.22%increase in biomass and 58.45%increase in relative abundance,while adding N alone reduced leg-ume performance as measured by 39.54%decrease in biomass and 50.36%in relative abundance.combining P and N addition did not mitigate the negative effect of N addition on legume performance and,surprisingly,suppressed legume biomass by 53.14%and relative abundance by 63.51%.N and P addition altered the balance of light competition between grasses and legumes as indicated by the changes in light levels,plant heights and litter accumulation.However,there were no obvious changes in legume species richness in response to N and P within our experimental timeframe.this study provides further evidence of the importance of P as a co-limiting nutrient in alpine grasslands,contrary to the traditional view that N limitation predominates in such regions.the contrasting effects of N and P addition on legume performance provide important insights into potential changes in legume performance in nutrient-limited grasslands following N and P enrichment under climate change,with implications for nutrient management in alpine grasslands.

Hydration, microstructure and autogenous shrinkage behaviors of cement mortars by addition of superabsorbent polymers

Superabsorbent Polymer(SAP)has emerged as a topic of considerable interest in recent years.The present study systematically and quantitively investigated the effect of SAP on hydration,autogenous shrinkage,mechanical properties,and microstructure of cement mortars.Influences of SAP on hydration heat and autogenous shrinkage were studied by utilizing TAM AIR technology and a non-contact autogenous shrinkage test method.Scanning Electron Microscope(SEM)was employed to assess the microstructure evolution.Although SAP decreased the peak rate of hydration heat and retarded the hydration,it significantly increased the cumulative heat,indicating SAP helps promote the hydration.Hydration promotion caused by SAP mainly occurred in the deceleration period and attenuation period.SAP can significantly mitigate the autogenous shrinkage when the content ranged from 0 to 0.5%.Microstructure characteristics showed that pores and gaps were introduced when SAP was added.The microstructure difference caused by SAP contributed to the inferior mechanical behaviors of cement mortars treated by SAP.

Classify the Higgs decays with the PFN and ParticleNet at electron-positron colliders

Various Higgs factories are proposed to study the Higgs boson precisely and systematically in a modelindependent way.In this study,the Particle Flow Network and ParticleNet techniques are used to classify the Higgs decays into multicategories,and the ultimate goal is to realize an"end-to-end"analysis.A Monte Carlo simulation study is performed to demonstrate the feasibility,and the performance looks rather promising.This result could be the basis of a"one-stop"analysis to measure all the branching fractions of the Higgs decays simultaneously.

An iterative weighting method to apply ISR correction to e+e−hadronic cross-section measurements

Initial State Radiation(ISR)plays an important role in e+e−collision experiments such as the BESIII.To correct the ISR effects in measurements of hadronic cross-sections of e+e−annihilation,an iterative method that weights simulated ISR events is proposed here to assess the efficiency of event selection and the ISR correction factor for the observed cross-section.The simulated ISR events were generated only once,and the obtained cross-sectional line shape was used iteratively to weigh the same simulated ISR events to evaluate the efficiency and corrections until the results converge.Compared with the method of generating ISR events iteratively,the proposed weighting method provides consistent results,and reduces the computational time and disk space required by a factor of five or more,thus speeding-up e+e−hadronic cross-section measurements.

Correlation between morphology parameters and skid resistance of asphalt pavement

Pavement skid resistance is critical for contributing to traffic safety.In this study,two pavement specimens were fabricated using different aggregate gradations and binder contents.Compaction efforts were made to ensure the same porosity of the two specimens.Some parameters related to the surface morphology were measured using the sand patching method and a 3D laser.The parameters include mean texture depth(MTD),interface roughness(R_(a)),skewness(R_(sk)),kurtosis(R_(ku)),fractal dimension(D)and parameters related to material ratio curve.Relationships between these parameters and skid resistance were quantitatively developed.Skid resistance increased along with the increase of MTD,R_(a) and D.From the surface A to surface B,MTD increased from 0.23 to 1.10 mm,R_(a) increased from 0.93 to 1.80 mm,D increased from 2.25 to 2.43 and the British Pendulum Number increased from 80 to 97 accordingly.The comprehensive analysis could assist scholars and practitioners to facilitate the understanding of tyre-pavement interaction and further assist pavement design.