Effect of anti-CIRP antibody on inflammatory response, tumor formation and abdominal aortic aneurysm in rats

Purpose: To investigate the effect of anti-cold induced RNA binding protein (CIRP) antibody on inflammation, tumor formation and abdominal aortic aneurysm in rats.Methods: Thirty healthy male Wistar rats were assigned to pseudo-operation, abdominal aortic aneurysm model, and anti-CIRP groups, with 10 in each group. The levels of CIRP, TNF- α, monocyte giant cytokine chemokine-1 (MCP-1), Toll-like receptor 4 (TLR4)) and nuclear factor kappaB (NF- κB)were determined compared among the groups.Results: At both 2 and 4 weeks, the expression of CIRP protein in the model group was significantly higher than that in the sham operation group (p < 0.05). At these two time-points, tumor formation and maximum diameter were higher in anti-CIRP and model control rats than in pseudo-operation rats. After 4 weeks of treatment, the protein expressions of TNF- α, MCP-1, TLR4 and NF-κB were higher in anti-CIRP and model control rats than in pseudo-operation rats, but were lower than model control values (p < 0.05).Conclusion: CIRP expression is significantly increased in abdominal aortic aneurysm tissue and serum, and is involved in the onset and progress of abdominal aortic aneurysm. Anti-CIRP antibody therapy effectively suppresses tumorigenesis, and inhibits tumor wall inflammatory reaction viaTLR4/NF-κB pathway. This finding provides a clue and new strategy for the clinical management of abdominal aortic aneurysm. Keywords: CIRP, Abdominal aortic tumor wall, Inflammatory reaction, Protein expression, Tumor bod

Modelling cracking damage of asphalt mixtures under compressive monotonic and repeated loads using pseudo J-integral Paris’ law

Field observations and mechanical analyses have shown that cracks accompany rutting in asphalt mixtures under external compressive loads. This study aims to model crack growth in asphalt mixtures under compressive monotonic and repeated loads. Using energy equilibrium and viscoelastic Griffith fracture criterion, a damage density characterising the cracks in mixtures is derived as a function of stress, nonlinear viscofracture strain, asphalt film thickness and bond energy. Crack evolution is modelled by pseudo J-integral Paris’ law. Six types of asphalt mixture were tested by monotonic compressive strength tests at 40°C. Two were further tested at four more temperatures and four more loading rates, respectively. Repeated load test results for the same mixtures were obtained from previous studies. The different shape of the damage density curve (S-shape for monotonic load and increasing exponential shape for repeated load) demonstrates the dependence of damage growth on loading mode, due to different energy release rates. Pseudo J-integral Paris’ law can model the crack growth in mixtures and capture the post-peak softening behaviour under a monotonic load. The Paris’ law coefficients (A and n) are independent of loading mode (monotonic or repeated), rate or temperature. They are fundamental material properties and can be used to predict crack growth under varying loading and temperature conditions

Molecular dynamics investigation of interfacial adhesion between oxidised bitumen and mineral surfaces

The interfacial adhesion between oxidised bitumen and mineral surfaces at dry and wet conditions was investigated using molecular dynamics (MD) simulations. Molecular models were built for virgin and oxidised bitumen components including saturate, aromatic, resin and asphaltenes. The bitumen models and four representative mineral substrates (namely quartz, calcite, albite and microcline) were employed to construct bitumen-mineral interface systems. These models were validated by the experimental results and MD simulations reported in the literature. The hardening mechanism of the aged bitumen was analysed by comparing the density, cohesive energy density and fraction of free volume between the virgin and oxidised bitumen. Work of adhesion was computed to quantify the adhesive bonding property of the bitumen-mineral interface systems for the virgin, lightly oxidised and heavily oxidised bitumen models under dry and wet conditions. Results show that the oxidised products (carbonyl and sulfoxide) strengthen the intermolecular bonding, resulting in molecular aggregation and physical hardening of the aged bitumen. When bitumen becomes oxidised at the dry condition, the interfacial adhesion of bitumen-acidic minerals (quartz) is dominated by van der Waals interaction which decreases due to the increased bitumen-quartz intermolecular distance caused by the aggregated bitumen molecules during aging. In comparison, the interfacial adhesion of bitumen-strong alkali minerals (albite and microcline) is dominated by electrostatic energy which increases due to higher polarity introduced by the oxidised products. For the bitumen-weak alkali mineral (calcite), the interfacial adhesion is attributed to both electrostatic energy and van der Waals energy, where compared to the virgin bitumen, the electrostatic energy becomes lower for the lightly-oxidised bitumen due to the increased bitumen-mineral distance but becomes higher for the heavily-oxidised bitumen due to higher polarity. At wet condition, water is the dominating factor that affects (weakens) the interfacial adhesion between the bitumen and the acidic minerals (quartz), and the oxidative aging of bitumen is the major factor that affects (strengthens) the interfacial adhesion between the bitumen and the strongly alkaline minerals (albite and microcline). For the weak alkali minerals such as calcite, both water and bitumen aging can significantly affect the interfacial adhesion

Impact of biological clogging on the barrier performance of landfill liners

The durability of landfill mainly relies on the anti-seepage characteristic of liner system. The accumulation of microbial biomass is effective in reducing the hydraulic conductivity of soils. This study aimed at evaluating the impact of the microorganism on the barrier performance of landfill liners. According to the results, Escherichia coli. produced huge amounts of extracellular polymeric substances and coalesced to form a confluent plugging biofilm. This microorganism eventually resulted in the decrease of soil permeability by 81%–95%. Meanwhile, the increase of surface roughness inside the internal pores improved the adhesion between microorganism colonization and particle surface. Subsequently, an extensive parametric sensitivity analysis was undertaken for evaluating the contaminant transport in landfill liners. Decreasing the hydraulic conductivity from 1 × 10−8 m/s to 1 × 10−10 m/s resulted in the increase of the breakthrough time by 345.2%. This indicates that a low hydraulic conductivity was essential for the liner systems to achieve desirable barrier performance

Design, Implementation and Modeling of Flooding Disaster-Oriented USV

Although there exist some unmanned surface platforms, and parts of them have been applied in flooding disaster relief, the autonomy of these platforms is still so weak that most of them can only work under the control of operators. The primary reason is the difficulty of obtaining a dynamical model that is sufficient rich for model-based control and sufficient simple for model parameters identification. This makes them difficult to be used to achieve some high-performance autonomous control, such as robust control with respect to disturbances and unknown dynamics and trajectory tracking control in complicated and dynamical surroundings. In this chapter, a flooding disaster-oriented unmanned surface vehicle (USV) designed and implemented by Shenyang Institute of Automation, Chinese Academy of Sciences (SIA, CAS) is introduced first, including the hardware and software structures. Then, we propose a quasi-linear parameter varying (qLPV) model to approach the dynamics of the USV system. We first apply this to solve a structured modeling problem and then introduce model error to solve an unstructured modeling problem. Subsequently, the qLPV model identification results are analyzed and the superiority compared to two linear models is demonstrated. At last, extensive application experiments, including rescuing rope throwing using an automatic pneumatic and water sampling in a 2.5 m radius circle, are described in detail to show the performance of course keeping control and GPS point tracking control based on the proposed model

Impact of minerals and water on bitumen-mineral adhesion and debonding behaviours using molecular dynamics simulations

This study aims to evaluate the effects of mineral types and water on the adhesion properties and debonding behaviours of bitumen-mineral interface systems. A molecular dynamics modelling approach was employed to simulate the interactions between minerals and bitumen with and without the presence of water. Four representative minerals (quartz, calcite, albite and microcline) were selected to build the mineral-bitumen interface systems and the mineral-water-bitumen interface systems in the molecular dynamics models. The adhesion property between minerals and bitumen was quantified by work of adhesion, defined as the energy required to separate a unit area of the bitumen-mineral interface. The debonding behaviour between minerals and bitumen is characterised by work of debonding, defined as the energy required to displace bitumen by water at the mineral-bitumen interface. The simulation results were validated by available experimental results reported in the literature. It was found that the work of adhesion and the work of debonding for the four bitumen-minerals interface systems are ranked microcline > albite > calcite > quartz at both dry and wet conditions. Moisture can reduce the adhesion between minerals and bitumen by 82%, 84%, 18% and 1% for the quartz, calcite, albite and microcline, respectively. The adhesion between minerals and bitumen is attributed to the non-bond interaction energy, in which the major component is van der Waals interaction for neutral minerals (e.g., quartz) and the electrostatic interaction for the alkali minerals (e.g., calcite, albite and microcline). The bitumen-mineral debonding is a thermodynamically favourable process with reduced total potential energy of the system. It is concluded that the bitumen-mineral adhesion and debonding behaviours strongly depends on the chemistry and mineralogical properties of the minerals. This work provides a fundamental understanding of the adhesion and debonding behaviours of the bitumen-mineral interface at the atomistic scale

Kinetics-based aging evaluation of in-service recycled asphalt pavement

Reclaimed asphalt pavement (RAP) is a type of material that already suffers long-term aging in the field, so its aging characteristics become prominent since they are closely related to premature distresses and longevity of recycled pavements. While most of investigations of RAP mixtures are carried out in the laboratory, this study focuses on in situ aging of asphalt pavements with RAP overlays. A kinetics-based aging modeling approach is proposed to analyze and quantify long-term field aging of RAP overlays using the Falling Weight Deflectometer (FWD) data and climate data. The kinetics-based approach contains a modulus aging model with kinetic parameters (e.g. aging activation energy) for asphalt mixtures. Eight asphalt overlays are selected with different mixtures (RAP and virgin), thickness (50 mm and 125 mm), and surface preparation (milling and no milling). An asphalt pavement with an overlay has a composite aging process since the aging speeds of different asphalt layers are different. Thus an approach to separate the FWD modulus is developed in order to obtain the actual aging behaviors and properties of the overlay. By applying the kinetics-based modeling to the separated FWD moduli, the aging activation energies of both the overlays and old asphalt layers are determined. It is found that the RAP overlay has the highest aging activation energies and slowest aging rates among the RAP overlay, virgin overlay, and old asphalt layer for the selected pavements. It also reveals through the aging activation energy that the thick overlays age slower than thin ones, and the overlays on milled pavements age slower than those placed without milling. The findings in terms of the aging activation energy can be used to explain the difference in the field performance of overlay pavement sections

Mechanistic-empirical models for better consideration of subgrade and unbound layers influence on pavement performance

It has been reported that the pavement performance predicted by the current mechanistic-empirical pavement design shows low or no sensitivity to subgrade and unbound layers. This issue has raised wide attention. Targeting this problem, this paper summarizes the process used by the authors to find better models of the influence of subgrade and unbound base course layers on the performance of flexible and rigid pavements. A comprehensive literature review is first conducted and the findings are categorized. It is found that the resilient modulus, permanent deformation, shear strength, and erosion are key factors. In particular, the properties that provide greater sensitivity are 1) the moisture-dependency of the modulus, shear strength, and permanent deformation; 2) stress-dependency of the modulus and permanent deformation; and 3) cross-anisotropy of the modulus. A number of unbound layer/subgrade models have been located and categorized. Three criteria are developed to identify the candidate models in terms of the degree of susceptibility, degree of accuracy, and ease of development. The first two criteria are used to evaluate the collected unbound layer/subgrade models, while associated development and implementation issues are planned as subsequent work. Two models that the authors previously developed are selected as examples to illustrate the improvement of the performance prediction, including the moisture-sensitive, stress-dependent, and cross-anisotropic modulus model for unbound layers and stress-dependent mechanistic-empirical permanent deformation model for unbound base layers. These two models are verified through laboratory tests and numerical simulations. Moreover, they are compared to their counterparts in the AASHTOWare Pavement ME Design. The advantages of accuracy and sensitivity to the operational conditions (e.g. moisture, traffic stress, and load-induced/particle-induced anisotropy) are obvious. In addition to these two models, the development of the shear strength model and erosion model are sketched. The candidate models need further development and implementation, which address issues such as hierarchical inputs, calibration/validation, and implementation. These are the on-going and planned work on this topic to better incorporate the influence of subgrade and unbound layers so as to contribute to the improvement of pavement designs

Structural performance and sustainability assessment of cold central-plant and in-place recycled asphalt pavements: A case study

This paper aimed at assessing the structural performance and sustainability of cold recycled asphalt pavements. Four cold recycling technologies were investigated, including the cold central-plant recycling with emulsified and foamed asphalt binders (i.e., CCPR-E and CCPR-F), and the cold in-place recycling with emulsified and foamed asphalt binders (i.e., CIR-E and CIR-F). Firstly, the laboratory tests were conducted to comprehensively evaluate the dynamic modulus, rutting, and cracking performance of cold recycled asphalt mixtures. Subsequently, these laboratory results were used to determine the inputs of cold recycled asphalt mixtures for the Pavement ME Design program, which was employed to predict the pavement performance. Meanwhile, the National Center for Asphalt Technology also constructed four cold recycled pavement sections in the field. The monitored and predicted pavement performance showed similar trends in the first two years, but the Pavement ME Design program over predicted the rut depth of these sections. The pavement performance results confirmed that the bottom-up fatigue cracking was a negligible distress mode for cold recycled asphalt pavements. In the following, the life cycle cost analysis and life cycle assessment were conducted to evaluate the four different cold recycling projects. The life cycle cost analysis results demonstrated that all of the four cold recycling projects yielded less net present values than the HMA project. The life cycle assessment data indicated that the cold recycling technologies reduced the energy consumption by 56–64%, and decreased the greenhouse gas emissions by 39–46%. Finally, this study found that the overlay and asphalt treated base thicknesses and climatic conditions had significant impact on the performance of cold recycled asphalt pavements