“过界”与“破界”之喻:粤港澳大湾区电影的建构与突围

当下,粤港澳大湾区电影的建构与突围,以“界”的隐喻呈现出来。聚焦跨境现象的《过界男女》《过春天》和《金都》,诉说着内地与香港地区在“一国两制”政策下的别样故事。《带你去见我妈》与《迷妹罗曼史》则展现了大湾区与其辐射区域更广阔的文化交融景观。至此,大湾区电影也就初步形成了“向内”的主体性建构。而《拆弹专家2》《雄狮少年》及《奇迹·笨小孩》则以更为成熟的市场化姿态,进一步挖掘和书写“大湾区特色”。无疑,在中国电影的地理版图上和地缘电影学的视域下,大湾区电影正在积极“向外”突围。

Smoothed particle hydrodynamics modeling and simulation of foundry filling process

A numerical model of foundry filling process was established based on the smoothed particle hydrodynamics（SPH）method.To mimic the constraints that the solid mold prescribes on the filling fluid,a composite treatment to the solid boundaries is elaborately designed.On solid boundary surfaces,boundary particles were set,which exert Lennard-Jones force on approaching fluid particles;inside the solid mold,ghost particles were arranged to complete the compact domain of near-boundary fluid particles.Water analog experiments were conducted in parallel with the model simulations.Very good agreement between experimental and simulation results demonstrates the success of model development.

Mechanical properties and friction-wear characteristics of VN/Ag multilayer coatings with heterogeneous and transition interfaces

The heterogeneous multilayer interface of VN/Ag coatings and transition multilayer interface of VN/Ag coatings were prepared on Inconel 781 and Si(100),and the microstructures,mechanical and tribological properties were investigated from 25 to 700℃.The results showed that the surface roughness and average grain size of VN/Ag coatings with transition multilayer interface are obviously larger than those of VN/Ag coatings with heterogeneous multilayer interface.The coatings with transition multilayer interface have higher adhesion force and hardness than the coatings with heterogeneous multilayer interface,and both coatings can effectively restrict the initiation and propagation of microcracks.Both coatings have excellent self-adaptive lubricating properties with a decrease of friction coefficient as the temperature increases,but their wear rates reveal a drastic increase.The phase composition of the worn area of both coatings was investigated,which indicates that a smooth Ag,Magnéli phase(V2O5)and bimetallic oxides(Ag3VO4 and AgVO3)can be responsible to the excellent lubricity of both coatings.To sum up,the coatings with transition multilayer interface have excellent adaptive lubricating properties and can properly control the diffusion rate and release rate of the lubricating phase,indicating that they have great potential in solving the problem of friction and wear of mechanical parts.

Towards the Mechanism of Mass Transfer of a Single Bubble

This paper focuses on the mechanism of interfacial mass transfer of a single bubble, based on the chemical potential driving force, an approach for calculating interfacial concentration in practical process is proposed. The absorption processes of bubble under both quiescent and mobile conditions are analyzed and discussed respectively. For a stationary absorption, only in the case of liquid bulk concentration near saturated value, the interfacial concentration could close to the equilibrium value ; For a moving bubble, under ordinary operating condition （Yo〉l）, the interfacial concentration is far from its equilibrium. Only under bulk concentration near saturated value or a smaller Yo（Yo〈0.1） which may involve the complication of additional resistance at interface induced by surface contamination or surfactant added, the interfacial concentration could be approximate to equilibrium value. The interfacial concentration close to the interface on liquid side for a single CO2 bubble absorbed by methanol is measured using a modern optical instrumentation in which the laser holographic interference method is adopted with a real-time and amplification technique. Experimental results show that the interfacial concentration decreases significantly with increasing Re and is far from the equilibrium one in a larger Re range. Experiments validate the proposed model.

Characterization of carbon fibers recovered through mechanochemical-enhanced recycling of waste carbon fiber reinforced plastics

In this study,we present the characterization of the carbon fibers recovered from the mechanochemical-enhanced recycling of carbon fiber reinforced fibers.The objectives of the study were to investigate the effect of our modified recycling method on the interfacial properties of recovered fibers.The reinforced plastics were recycled;the recycling efficiency was determined and the recovered fibers were sized using 1 wt%and 3 wt%concentration of(3-aminopropyl)triethoxysilane.We characterized the morphologies utilizing the electron spectroscopy for chemical analysis(ESCA),atomic force microscopy(AFM),FTIR-attenuated total reflection(ATR)spectroscopy and scanning electron microscopy(SEM).Although the surface of the fibers had no cracks,there was evidence of contaminations which affected the interfacial properties and the quality of the fibers.Results showed that the trends in the recovered and virgin fibers were similar with an increase in sizing concentration.The results highlighted the perspectives of increasing the quality of recovered fibers after the recycling process.

The Mechanism of Interfacial Mass Transfer in Gas Absorption Process

Based on the method of molecular thermodynamics, the mass transfer mechanism at gas-liquid interface is studied theoretically, and a new mathematical model is proposed. Using laser holographic interference technique, the hydrodynamics and mass transfer characteristics of CO2 absorption are measured. It is shown that the calculated results are in good agreement with the experimental data.

Global existence and blow up of a degenerate parabolic system

This paper deals with positive solutions of a degenerate parabolic system: u t= Δ u m+ v p ln α(h+u), v t= Δ v n+u q ln β(h+v) with homogeneous Dirichlet boundary conditions and positive initial conditions. This system describes the processes of diffusion of heat and burning in two component continuous media with nonlinear conductivity and volume energy release. We obtain the global existence and blow up results of the solution relying on comparison with carefully constructed upper solutions and lower solutions.

Statistical damage model for quasi-brittle materials under uniaxial tension

Based on the parallel bar system, combining with the synergetic method, the catastrophe theory and the acoustic emission test, a new motivated statistical damage model for quasi-brittle solid was developed. Taking concrete for instances, the rationality and the flexibility of this model and its parameters-determining method were identified by the comparative analyses between theoretical and experimental curves. The results show that the model can simulate the whole damage and fracture process in the fracture process zone of material when the materials arc exposed to quasi-static uniaxial tensile traction. The influence of the mesoscopic damage mechanism on the macroscopic mechanical properties of quasi-brittle materials is summarized into two aspects, rupture damage and yield damage. The whole damage course is divided into the statistical even damage phase and the local breach phase, corresponding to the two stages described by the catastrophe theory. The two characteristic states, the peak nominal stress state and the critical state are distinguished, and the critical state plays a key role during the whole damage evolution course.

Diffusion bonding of Al 7075 and Mg AZ31 alloys:Process parameters, microstructural analysis and mechanical properties

Al 7075 and Mg AZ31 alloys were joined by diffusion bonding method. Joining process was performed in pressure range of 10-35 MPa at temperatures of 430-450 ℃ for 60 min under a vacuum of 13.3 MPa. The microstructure evaluation, phase analysis and distribution of elements at the interface were done using scanning electron microscopy （SEM）, energy-dispersive X-ray spectroscopy （EDS） and X-ray diffraction （XRD）. The pressure of 25 MPa was determined as the optimum pressure in which the minimum amount of plastic deformation takes place at the joint. Different reaction layers containing intermetallic compounds, such as Al12Mg17, Al3Mg2 andα（Al） solid solution, were observed, in interfacial transition zone （ITZ）. Thickness of layers was increased with increasing the operating temperature. According to the results, diffusion of aluminum atoms into magnesium alloy was more and the interface movement towards the Al alloy was observed. The maximum bond strength of 38 MPa was achieved at the temperature of 440 ℃ and pressure of 25 MPa. Fractography studies indicated that the brittle fracture originated from Al3Mg2 phase.

Experimental study on the shear behavior of grout-infilled specimens and micromechanical properties of grout-rock interface

The grout-rock interfacial property is one of the key factors associated with the strength of grouted rock masses.In this study,direct shear tests and nanoindentation tests were adopted to investigate the mechanical properties of the grout-rock interface at both the macroscale and microscale.The cohesion of the cement specimens was higher than that of the grout-infilled joint specimens,while their internal friction angle was lower than that of the grout-infilled joint specimens.A“separation method”for identifying the different phases according to the qualitative and quantitative estimations was introduced,and the irregular interfacial transition zone(ITZ)thickness and elastic modulus were estimated.The ITZ thickness of the grout-infilled sandstone specimen ranged from 0 to 30μm,whereas it was within the range of 10-40μm for the grout-infilled mudstone specimen.The average elastic modulus of the ITZ in grout-infilled sandstone and mudstone specimens was approximately 58.2%and 54.1%lower than that of the bulk grout,respectively.Regarding the incidence of the rock type,the interlacing between the grout and sandstone was better developed.The ITZ with a higher porosity and lower modulus had a significant effect on the mechanical properties of the grout-infilled specimens.

Expression of Bmi-1,P16,and CD44v6 in Uterine Cervical Carcinoma and Its Clinical Significance

Objective Bmi-1, a putative proto-oncogene, is a core member of the polycomb gene family, which is expressed in many human tumors. The p16 protein negatively regulated cell proliferation, whereas CD44v6 is associated with proliferation as an important protein. Additionally, CD44v6 is an important nuclear antigen closely correlated to tumor metastasis. Tlle present study aims to investigate the expression and significance of Bmi-1, p16, and CD44v6 in uterine cervical carcinoma （UCC）. Methods A total of 62 UCC, 30 cervical neoplasic, and 20 normal cervical mucosal tissues were used ill the current study. The expression of Bmi-1, p16, and CD44v6 in these tissues was determined using immunohistochemical assay. The relationships among the expression of these indices, the clinicopathologic features of UCC, and the survival rate of UCC patients were also discussed. The correlation between Bmi-1 protein expression and p16 or CD44v6 protein in UCC was analyzed. Results The expression of Bmi-l, p16, and CD44v6 was significantly high in cervical carcinoma compared with that in tlle cervical neoplasia and normal colorectal mucosa （P〈0.05）. The over-expression of Bmi-1 protein in UCC was apparently related to the distant metastasis （P〈0.01） and the tumor, nodes and metastasis-classification, i.e. the TNM staging, World Health Organization （P〈0.05）. Nevertheless, the positive expression of p16 protein in UCC was not significantly associated with the clinicopathologic features （P〉0.05）. The Kaplan-Meier survival analysis showed that the over-expression of Bmi-1 significantly decreased the survival rate of UCC patients （P〈0.05）. A strong correlation indicated that there was statistical significance between the expression of Bmi-1 and CD44V6 proteins in UCC （r=0.419, P=0.001）. Conclusions The over-expression of Bmi-1 and CD44v6 protein closely correlate to the tumorigenesis, metastasis, and prognosis of UCC. Bmi-I and CD44v6 may be used to predict the prognosis of cervical carcinoma. Bmi-1 may indirectly regulate the expression of CD44v6 in UCC patients. The positive expression of p16 protein is possibly associated with the tumorigenesis, but not with the metastasis or prognosis of UCC.

Effect of Increasing Course of Temperature and Pressure on Polypropylene Degradation in Supercritical Water

The effect of increasing course of temperature and pressure on polypropylene （PP） degradation in supercritical water was investigated for developing a process of recycling waste plastic. A group of experiments was carded out in a reaction system at a pressure of 26MPa, temperature of 380℃ or 400℃ for 30min, 70min, and 120min by Course One （the increasing course of temperature and pressure is via gaseous regions to supercritical regions）, and the other group was carried out at corresponding holding conditions by Course Two （the increasing course of temperature and pressure is via liquid regions to supercritical regions）. The time of the increasing courses was about 30min. Products were analyzed by Ostward-type viscometer, gaseous chromatography, and mass spectrometers （GC/MS）. Characterization results suggested that different increasing courses of temperature and pressure would give rise to different results, although they were treated under the similar holding conditions. It was also found that Course Two was more effective on PP degradation in supercritical water.

Effect of meridional wind on gap-leaping western boundary current

Using a 1.5-layer reduced-gravity nonlinear shallow-water equation model, we studied the effect of the meridional wind on the western boundary currents (WBC) at critical states with hysteresis courses. The results of the simulation indicate that the WBC is prone to penetrating into the gap under northerly winds, and its path is more difficult to alter due to the larger interval between the two critical transition curves (C1P and C1L). For southerly winds, the WBC is prone to leaping across the gap, and its path is easier to alter due to the smaller interval between the two critical transition curves. The simulation results also indicate that the meridional winds over the southern region of the gap are the dominant factor determining the formation of the WBC. The dynamic mechanism influencing the transport of WBC near the gap is both Ekman transport and the blocking of Ekman transport. Ekman transport induced by northerly winds may reduce the transport of the WBC, causing the β-effect to dominate the meridional advection (promoting the penetration). Southerly winds, however, may enhance the transport of the WBC, causing the meridional advection to dominate the β-effect (promoting the leaping state). These results explain some structural features of the Kuroshio at the Luzon Strait.

Improving performance of recycled aggregate concrete with superfine pozzolanic powders

Phosphorous slag （PHS）, ground granulated blast-furnace slag （GGBS） and fly ash （FA） were used as replacements of Portland cement to modify the microstruc^xe of recycled aggregate concrete （RAC）. A new manufacturing method named ＂W3T4＂ was proposed to improve the performances of interracial transition zone （ITZ） between recycled aggregate and mortar. The mechanical properties and the durability of RAC were tested, which show that this new manufacturing method improves the properties of RAC, and the GGBS with finest size makes a great contribution to the performance of RAC due to its better filling effect and much earlier pozzolanic reaction. Combined with GGBS, the effects of PHS on the retardation of setting time can be alleviated and the synergistic effect helps to make a more compact RAC. For the RAC with 25% of the recycled aggregate （RA） replacement and 10% PHS ＋ 10% GGBS additives, the compressive strength increases by 25.4%, but the permeability decreases by 64.3% with respect to the reference concrete made with nature aggregates. The micro-mechanisms of these improvements were investigated by the scanning electron microscope （SEM）. The SEM images show that the new manufacturing method, adding superfine pozzolanic powders and super-plasticizer benefits, makes a much denser ITZ in RAC.

Critical Heat Flux with Subcooled Flowing Water in Tubes for Pressures from Atmosphere to Near-Critical Point

During last 45 years, two groups of the experimental data on critical heat flux were obtained in bare tubes, covering the pressures from atmosphere to near-critical point. One group of the data were obtained in the inner diameter of 2.32, 5.16, 8.05, 10.0 and 16.0 mm, respectively, with the ranges of pressure of 0.1-1.92 MPa, velocity of 1.47-23.3 m/s, local subcooling of 3.7-108.7 ℃ and heat flux of up to 38.3 MW/m2. Another group of the data were obtained in the inner diameter of 4.62, 7.98 and 10.89 mm, respectively, with the ranges of pressure of 1.7-20.6 MPa, mass flux of 454-4,055 kg/（m2.s） and inlet subcooling of 53-361 ℃. The results showed complicated effects of the pressure, mass flux, subcooling and diameter on the critical heat flux. They were formulated by two empirical correlations. A mechanistic model on the limit of heat transfer capability from the bubbly layer to the subcooled core was also proposed for all the results.

Role of transition-metal electrocatalysts for oxygen evolution with Si-based photoanodes

A comprehensive understanding of the role of the electrocatalyst in photoelectrochemical(PEC)water splitting is central to improving its performance.Herein,taking the Si-based photoanodes(n^(+)p-Si/SiO_(x)/Fe/FeOx/MOOH,M=Fe,Co,Ni)as a model system,we investigate the effect of the transition-metal electrocatalysts on the oxygen evolution reaction(OER).Among the photoanodes with the three different electrocatalysts,the best OER activity,with a low-onset potential of∼1.01 VRHE,a high photocurrent density of 24.10 mA cm^(-2)at 1.23 VRHE,and a remarkable saturation photocurrent density of 38.82 mA cm^(-2),was obtained with the NiOOH overlayer under AM 1.5G simulated sunlight(100 mW cm^(-2))in 1 M KOH electrolyte.The optimal interfacial engineering for electrocatalysts plays a key role for achieving high performance because it promotes interfacial charge transport,provides a larger number of surface active sites,and results in higher OER activity,compared to other electrocatalysts.This study provides insights into how electrocatalysts function in water-splitting devices to guide future studies of solar energy conversion.

Bonding between Aggregates and Cement Pastes in Concrete

This investigation was carried out to study the effect of aggregate roughness on ITZ （interfacial transition zone） at same water/cement ratio and the influence of silica fume on the bond strength. On the experimental side, two types of aggregates （limestone and granite） were used, which were prepared with broken surface. Cement （Type I） was used with same w/c ratio for all batches. In order to study the effect of silica fume on the bond, the same mixes were produced with 8% silica fume. Three different tests were performed： ＂pull a part＂, Brazilian test and compressive strength test. The specimens for Brazilian and compressive strength were tested after 28 days, while the ＂pull a part＂ specimens were tested after 29 days. The result showed that the bond strength is influenced by the surface roughness of aggregate. For the same mix, limestone recorded higher bond strength than granite. Moreover, the bond strength is increased by adding the silica fume.

An Investigation on Polypropylene Degradation in Supercritical Water Adding Benzoyl Peroxide

The effect of benzoyl peroxide （BPO） on polypropylene （PP） degradation in supercritical water was investigated with the aim of developing a process for recycling of waste plastics. A series of experiments with and without BPO were carried out at temperatures of 653 K and 673 K under pressure about 26 MPa for 30, 75 and 120 min respectively. Products were analyzed by an Ostward-type viscometer, gas chromatography and spectrometry （GC/MS） etc. The results indicated that mean molecular weight of the samples decreased greatly along with the time elapsing or with the temperature increasing, and PP was decomposed to Miphatic and cycloparaftinic hydrocarbons but a few benzenoid hydrocarbons. By comparing the experiments with and without BPO, it was made clear that BPO is an effective additive on PP degradation in supercritical water.

Seroprevalence of Porcine Cysticercosis and Associated Risk Factors in Pigs Slaughtered in Abattoirs in Thika, Kiambu County, Kenya

Taenia solium is an important food-bome pathogen worldwide and is emerging as a serious public health risk in both rural and urban communities where pigs are raised and consumed. Adult tapeworms are found in the intestines of humans while the developmental larval forms occur in the muscles and organs constituting cysticercosis of pigs and humans. Cysticercosis has a worldwide distribution, mainly related to poor hygiene and sanitation and consumption of infected pork. Pigs get infected through consumption of food and contaminated with human faeces containg eggs. In recent years pork consumption has increased with the opening up of pork eating centres. Porcine cysticercosis has previously been reported in Kenya, however, there are scarce data on the occurrence of the disease, as well as on the risk factors for transmission, in key production and consumption areas including Thika. The purpose of the study was to determine the seroprevalence of porcine cysticercosis in slaughtered pigs and associated risk factors for occurrence of the disease in selected abattoirs in Thika. Systematic random sampling was used to select a total of 276 pigs. The source of the slaughter pigs was derived fi＇om the movement permits, the breed, sex and estimation of age was done at ante mortem examination. The slaughter and meat inspection processes were carried out by the slaughter house personnel and the investigators only observed and received the outcome of the inspection. Blood samples were collected fi＇om each identified pig at slaughter, processed and analyzed using purified Taenia solium antigen ELISA commercial kit. The results meat inspection showed that none of the pigs in this study had any visible cysts whereas 4.35% of the pigs were seropositive which poses public health risk.

Framework Definitions of Effects and Phenomena and Examples in Differential and Difference Equations

Framework definitions of earlier informally used notions of effect and phenomenon are proposed, examples of their role in developing mathematics are given. Phenomena of singular cycle and deepening boundary layer in the theory of singularly perturbed differential equations and ancient popular synergetic process described by system of random difference equations are presented.