Internal co-seismic deformation and curvature effect based on an analytical approach

In this study, we present a new method to compute internal co-seismic deformations of a homoge- neous sphere, based on our previous approach （Dong et al. 2016）. In practical numerical computations, we consider a strike-slip point source as an example, and compute the vertical co-seismic displacement on different internal spherical surfaces （including the Earth surface）. Numerical results show that the internal co-seismic deformations are generally larger than that on the Earth surface; especially, the maximum co-seismic displacement appears around the seismic source. The co-seismic displacements are opposite in sign for the areas over and beneath the position of the seismic source. The results also indicate that the curvature effect of the internal deformation is pretty large, and larger than that on the Earth surface. The results indicate that the dislocation theory for a sphere is necessary in computing internal co-seismic deformations.

The effect of internal tides on the vertical structure of tidal current in the North Huanghai Sea

The tidal current is generally predominant in China's offshore areas. The vertical structure of the observedtidal current is quite complicated with the presence of seasonal thermocline. The observed tidal current may be divided into two parts, an averaged barotropic tide current and a variation tide current. A method for studying the vertical structure of tidal current is developed from the constitution and distribution of energy, and the vertical structure of the observed tide current in the North Huanghai Sea is studied on the basis of the method. The result shows that the reason why the energy of the tidal current is concentrated on the neighbourhood of the thermocline mainly lies in the internal tides i under certain conditions, the fact that the direction of the internal tide current above the thermocline is opposite to the one below the thermocline will be able to cause the rotary directions of the observed tidal current above and below the thermocline to be in opposite. The interaction between the averaged barotropic and the variation tide current plays an important role in forming the vertical structure of the tidal current, and it is mainly the interaction that results in the inho-mogeneous distribution of the tide current energy in the entire water column ; the ratio between the total energies of the internal tide current above the thermocline and the variation tide current in the entire water column is greater than the ratio between the total energies of that below the thermocline and the variation's. In a strong internal tide area such as the neighbourhood of Station L4, at diurnal tide frequency, the above-mentioned corresponding ratios are about 38. 82% and 29. 88%, respectively, and the energy of the internal tide current is about 68. 70%of the energy of the variation tide current; at semidiurnal tide frequency, the above-mentioned corresponding ratios are about 26. 61 % and 19. 73% , respectively, and the total internal tide current energy is about 46. 36% of the total variation tide current energy.

Undrained vane shear strength of sand-foam mixtures subjected to different shear rates

The shear strength of sand-foam mixtures plays a crucial role in ensuring successful earth pressure balance(EPB)shield tunneling.Since the sand-foam mixtures are constantly sheared by the cutterhead and the screw conveyor with varied rotation speeds during tunneling,it is non-trivial to investigate the effect of shear rates on the undrained shear strength of sand-foam mixtures under chamber pressures to extend the understanding on the tunneling process.This study conducted a series of pressurized vane shear tests to investigate the role of shear rates on the peak and residual strengths of sand-foam mixtures at different pore states.Different from the shear-rate characteristics of natural sands or clay,the results showed that the peak strength of sand-foam mixtures under high vertical total stress(σ_(v)≥200 kPa)and low foam injection ratio(FIR30%)decreased with the increase in shear rate.Otherwise,the peak strength was not measurably affected by shear rates.The sand-foam mixtures in the residual state resembled low-viscous fluid with yield stress and the residual strength increased slightly with shear rates.In addition,the peak and residual strengths were approximately linear with vertical effective stress regardless of the total stress and FIR.The peak effective internal friction angle remained almost invariant in a low shear rate(γ′<0.25 s1)but decreased when the shear rate continued increasing.The residual effective internal friction angle was lower than the peak counterpart and insensitive to shear rates.This study unveiled the role of shear rates in the undrained shear strength of sand-foam mixtures with various FIRs and vertical total stresses.The findings can extend the understanding of the rate-dependent shear characteristics of conditioned soils and guide the decision-making of soil conditioning schemes in the EPB shield tunneling practice.

Carbon dots derived from Poria cocos polysaccharide as an effective“on-off”fluorescence sensor for chromium(Ⅵ)detection

Chromium is a harmful contaminant showing mutagenicity and carcinogenicity.Therefore,detection of chromium requires the development of low-cost and high-sensitivity sensors.Herein,blue-fluorescent carbon quantum dots were synthesized by one-step hydrothermal method from alkali-soluble Poria cocos polysaccharide,which is green source,cheap and easy to obtain,and has no pharmacological activity due to low water solubility.These carbon quantum dots exhibit good fluorescence stability,water solubility,anti-interference and low cytotoxicity,and can be specifically combined with the detection of Cr(Ⅵ)to form a non-fluorescent complex that causes fluorescence quenching,so they can be used as a label-free nanosensor.High-sensitivity detection of Cr(Ⅵ)was achieved through internal filtering and static quenching effects.The fluorescence quenching degree of carbon dots fluorescent probe showed a good linear relationship with Cr(Ⅵ)concentration in the range of 1-100μM.The linear equation was F;/F=0.9942+0.01472[Cr(Ⅵ)](R;=0.9922),and the detection limit can be as low as 0.25μM(S/N=3),which has been successfully applied to Cr(Ⅵ)detection in actual water samples herein.

PREPARATION OF ASYMMETRIC POLYETHERKETONE FLAT AND HOLLOW FIBER MEMBRANES FOR GAS SEPARATION USING ACETIC ACID BASED COAGULANTS

Membranes for gas separation have developed significantly in the last twenty years,however,there is still a need for high temperature and chemically resistant membranes that exhibit good selectivity and gas permeability.Our study examines the fundamental properties of polyetherketone (PEK,a thermally stable and chemically resistant polymer) membranes prepared using concentrated sulphuric acid (98% H_2SO_4) as the solvent.Non-solvents used in the work included acetic acid,ethanol,methanol,glycerol,and water....

EFFECT OF INTERNAL FIXATION PLATES ON MICROCIRCULATION IN UNDER-PLATE CORTICAL BONES MICROANGIOGRAPHY AND SCANNING ELECTRONMICROSCOPY

To elucidate the effect of the internal fixation plates on the local bone blood sapply, we used microangiography and scanning electron microscopy to observe the morphological changes of microcirculation in the cortical bones obtained from intact rabbit tibiae on which plates of two different stiffness had been fixed for comparison. The results indicated that both rigid stainless steel plate and less rigid methyl methacrylate plate could induce the bone microcirculation under the plate to undergo a process from early depression to late reactive recruitment. The features of the microcircuiation recruitment such as vascular number, arrangement and dilatation varied with plates of different stiffness and were more obvious in the cortex fixed by rigid stainless steel plate.

Analysis of the internal charging data in medium earth orbit with numerical simulation and ground experiment

The deep dielectric charging effect monitor(DDCEM)has been designed to study the internal charging effect by measuring the charging currents and potentials inside the spacecraft.It is equipped on three Chinese navigation satellites in a circular medium earth orbit(MEO)with 22000 km average height and 55°inclinations.Numerical simulation based on the Geant4-RIC method was used to evaluate the data of DDCEM.The data during May to November 2019 on one of the three satellites show that the charging currents of DDCEM were negatively enhanced when the satellite moved into the outer radiation belt.The currents reached the negative maximum during a significant electron enhancement in September 2019.Positive currents were also detected besides negative currents that were caused by the deposition of electrons in the sensor.The causation of positive currents in the space environment may be that the low-energy electrons cannot penetrate the satellite skin and make it charging to negative potential,the reference ground of DDCEM that is connected to the satellite skin drops below zero by the low-energy electrons so that the output currents turn to positive.Ground experiment was used to simulate the causation of positive currents and the result verified our theory.

CURRENT STUDIES ON BIOLOGICAL EFFECTS OF LOW LEVEL INTERNAL IRRADIATION

The biological effects of relative low level internal irradiation were introduced. 1. Life span studies on carcinogenesis. Pacific Northwest Laboratory observed 3782 rats given a single inhalation of 239Pu O2 at initial lung burden ranging from 0.25 to 180 nCi. Significant life span shortening was found at lung dose > 8 Gy and it was indicated that the presence of a 'possible' threshold of about 1 Gy for lung tumor formation. 2. Health effects of radon and its progeny. Both experimental and epidemiological survey were studied. The nominal probability coefficient (fatality) for the public and workers are 7.90×105 per mJhm-3 (2.77 ×10~4 per working level month, WLM). 3. Health effects of 3H on postnatal brain development and neurobehavior, genetic effects, carcinogenic effects and adaptive effects of 3H were investigated. 4. Study on the effects of neuroendocrine system under low level irradiation of 75Se (Auger electron emitter) and 35S (β-particles emitter). The results showed that the neuroendocrine system is very sensitive to small dose of internal irradiation.

Nitrogen-doped fluorescence carbon dots as multi-mechanism detection for iodide and curcumin in biological and food samples

Iodine ion is one of the most indispensable anions in living organisms,particularly being an important substance for the synthesis of thyroid hormones.Curcumin is a yellow-orange polyphenol compound derived from the rhizome of Curcuma longa L.,which has been commonly used as a spice and natural coloring agent,food additives,cosmetics as well as Chinese medicine.However,excess curcumin may cause DNA inactivation,lead to a decrease in intracellular ATP levels,and trigger the tissue necrosis.Therefore,quantitative detection of iodine and curcumin is of great significance in the fields of food and life sciences.Herein,we develop nitrogen-doped fluorescent carbon dots(NCDs)as a multi-mechanism detection for iodide and curcumin in actual complex biological and food samples,which was prepared by a one-step solid-phase synthesis using tartaric acid and urea as precursors without adding any other reagents.An assembled NCDs-Hg^(2+) fluorescence-enhanced sensor for the quantitative detection of I^(-) was established based on a fluorescence“turn-off-on”mechanism in a linear range of 0.3-15μM with a detection limit of 69.4 nM and successfully quantified trace amounts of I^(-) in water samples and urine sample.Meanwhile,the as-synthesized NCDs also can be used as a fluorescent quenched sensor for curcumin detection based on the synergistic internal filtration effect(IFE)and static quenching,achieving a good linear range of 0.1-20μM with a satisfactory detection limit of 29.8 nM.These results indicate that carbon dots are potential sensing materials for iodine and curcumin detection for the good of our health.

交互联合上的国际进步和评估在都市化和 eco 环境之间完成

Global urbanization is exerting severe stress and having far-reaching impacts on the eco-environment, and yet there exists a complex non-linear coupling relationship between the two. Research on the interactive coupling effect between urbanization and the eco-environment will be a popular area of study and frontier in international earth system science and sustainability science in the next 10 years, while also being a high-priority research topic of particular interest to international organizations. This paper systematically collates and summarizes the international progress made in research on interactive coupling theory, coupling relationships, coupling mechanisms, coupling laws, coupling thresholds, coupling models and coupling optimization decision support systems. The research shows that urbanization and eco-environment interactive coupling theories include the Kuznets curve theory, telecoupling theory, planetary boundaries theory, footprint family theory and urban metabolism theory; most research on interactive coupling relationships is concerned with single- element coupling relationships, such as those between urbanization and water, land, atmosphere, climate change, ecosystems and biodiversity; the majority of research on interactive coupling mechanisms and laws focuses on five research paradigms, including coupled human and nature systems, complex social-ecological systems, urban ecosystems, social-economic-natural complex ecosystems, and urbanization development and eco-environment constraint ring; the majority of interactive coupling simulations use STIRPAT models, coupling degree models, multi-agent system models and big data urban computer models; and research has been carried out on urbanization and eco-environment coupling thresholds, coercing risk and optimal decision support systems. An objective evaluation of progress in international research on interactive coupling between urbanization and the eco-environment suggests that there are six main research focal points and six areas lacking research： a lot of research exists on macroscopic coupling effects, with little research on urban agglomeration and scale coupling effects; considerable research exists on sin-gle-dimension coupling effects, with little on multiple-dimension coupling effects; a great deal exists on ＂one-to-one＂ dual- element coupling effects, with little on ＂many-to-many＂ multiple-element coupling effects; a lot exists on positive feedback coupling effects, and little on negative feedback coupling effects; a great deal exists on empirical coupling effects, and little on theoretical coupling effects; a great deal exists on the use of simple quantitative methods, and little on using integrated simulation methods. Future studies should focus on coupling effects between urbanization in urban agglomerations and the eco-environment, spatial scale coupling effects, multi-dimensional coupling effects, telecoupling effects, ＂one-to-many＂ and ＂many-to-many＂ element coupling effects, and positive and negative feedback coupling effects. There is also a need to strengthen the development and application of dynamic models for multi-element,-scale,-scenario,-module and-agent integrated spatiotemporal coupling systems and further improve theoretical innovations in coupling effect research and integrate and form complete and diverse coupling theoretical systems.

Relationship between single and bulk mechanical properties for zeolite ZSM5 spray-dried particles

In this work typical mechanical properties for a catalyst support material, ZSM5 （a spray-dried granular zeolite）, have been measured in order to relate the bulk behaviour of the powder material to the single particle mechanical properties. Particle shape and size distribution of the powders, determined by laser diffraction and scanning electron microscopy （SEM）, confirmed the spherical shape of the spray-dried particles. The excellent flowability of the material was assessed by typical methods such as the Hausner ratio and the Cart index, This was confirmed by bulk measurements of the particle-particle internal friction parameter and flow function using a Schulze shear cell, which also illustrated the low compressibility of the material. Single particle compression was used to characterize single particle mechanical properties such as reduced elastic modulus and strength from Hertz contact mechanics theory. Comparison with surface properties obtained from nanoindentation suggests heterogeneity, the surface being harder than the core. In order to evaluate the relationship between single particle mechanical properties and bulk compression behaviour, uniaxial confined compression was carried out. It was determined that the Adams model was suitable for describing the bulk compression and furthermore that the Adams model parameter, apparent strength of single particles, was in good agreement with the single particle strength determined from single particle compression test.