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The purpose of this paper is to explore the possibility of an enhanced continuous liquid interface production (CLIP) with a porous track-etched membrane as the oxygen-permeable window, which is prepared by irradiating polyethylene terephthalate membranes with accelerated heavy ions.

Experimental approaches are carried out to characterize printing parameters of resins with different photo-initiator concentrations by a photo-polymerization matrix, to experimentally observe and theoretically fit the oxygen inhibition layer thickness during printing under conditions of pure oxygen and air, respectively, and to demonstrate the enhanced CLIP processes by using pure oxygen and air, respectively.

Owing to the high permeability of track-etched membrane, CLIP process is demonstrated with printing speed up to 800 mm/h in the condition of pure oxygen, which matches well with the theoretically predicted maximum printing speed at difference light expose. Making a trade-off between printing speed and surface quality, maximum printing speed of 470 mm/h is also obtained even using air. As the oxygen inhibition layer created by air is thinner than that by pure oxygen, maximum speed cannot be simply increased by intensifying the light exposure as the case with pure oxygen.

CLIP process is capable of building objects continuously instead of the traditional layer-by-layer manner, which enables tens of times improvement in printing speed. This work presents an enhanced CLIP process by first using a porous track-etched membrane to serve as the oxygen permeable window, in which a record printing speed up to 800 mm/h using pure oxygen is demonstrated. Owing to the high permeability of track-etched membrane, continuous process at a speed of 470 mm/h is also achieved even using air instead of pure oxygen, which is of significance for a compact robust high-speed 3D printer.

Blueberry contains bioactive compounds which are beneficial to organisms, such as phenolics and flavonoids. The purpose of this paper is to evaluate the potential protective effects of blueberry extracts (BE) on H₂O₂-induced HepG2 cells.

Cell protection was evaluated via the survivals of the cell. Reactive oxygen species (ROS) level, antioxidant enzyme and malondialdehyde (MDA) were detected. Western blot was carried out to analysis protein which was related to the cell apoptosis pathway. Changes in morphology including: cell total apoptosis/necrosis and G0/G1 cycle arresting were also concomitant.

The levels of ROS and malondialdehyde (MDA) reduced after the BE treatment while the contents of superoxide dismutase, and glutathione peroxidase (GSH-Px) increased in HepG2 cells induced by H2O2. Furthermore, mechanistic studies indicated that BE regulated the activation of mitochondrial apoptosis signal-regulating (Bcl-2, Bax). Qu was used as a positive control group. All these results demonstrated that the BE have a potential against oxidative stress in vitro.

Few studies have focused on the bioactivities of blueberry on oxidative stress. Taken together, the results confirm that polyphenol-enriched BE have the ability to protect against oxidative stress in cells. It has a great potential as a functional food ingredient to health benefits. Furthermore, this work showed the value of using simple biological models to screen for compounds that are of interest for food and pharmacological industry.

The purpose of this paper is to investigate the relationship between servant leadership and life satisfaction through the mediating role of workplace positive affect (WPA), and the moderating roles of collectivistic orientation and general self-efficacy.

Using a sample of 304 employees in a two-wave survey, the hypotheses were demonstrated with hierarchical regression analyses.

The results revealed that servant leadership was positively related to employee life satisfaction, and WPA served as a mediator between them. Moreover, collectivistic orientation and general self-efficacy moderated the relationship between servant leadership and WPA, and the indirect effect of servant leadership on life satisfaction via WPA.

The time-lagged research design of this study may limit the ability to draw causal conclusions. Moreover, as this research was conducted in a Chinese context, the question of the generalizability of our findings calls for more attention.

Leaders are encouraged to adopt the servant leadership style to facilitate employee life satisfaction and organizations should select and recruit managers with servant leadership qualities. Furthermore, because employees’ collectivistic orientation and general self-efficacy moderate the effects of servant leadership on followers’ outcomes, managers need to take individual differences into consideration when they implement managerial strategy.

This research contributed to a burgeoning stream of servant leadership literature by investigating the functions of servant leadership in promoting life satisfaction, and exploring the affective mechanism linking servant leadership and life satisfaction as well as the boundary conditions of collectivistic orientation and general self-efficacy.

The purpose of this paper is to investigate consumer preference of and willingness to pay for eco-labelled eggs using cross-sectional data collected from Chongqing Municipality in China.

This study employs both conditional logistic model and mixed logistic model to conduct the empirical analysis.

The empirical results show that individual heterogeneous preference and attributes of eco-labelled eggs significantly influence consumer choices. More specifically, higher per capita income, families with pregnant women or children, higher level of trust in and knowledge of eco-labels contribute positively to choosing eco-labelled eggs, and attributes of eco-labelled eggs such as certification labels, free-range husbandry, and nutrition enrichment significantly increase consumer utility. Generally, the price premium that consumers are willing to pay for eggs containing “organic”, “free-range husbandry”, and “nutrition enrichment” labels is 375.0% more, equivalent to 42.8 Yuan/kg.

This study used first-hand survey data to reveal consumers’ heterogeneous preference of and willingness to pay for eco-labelled eggs based on the random utility theory.

This paper aims to study the agent learning from expert demonstration data while incorporating reinforcement learning (RL), which enables the agent to break through the limitations of expert demonstration data and reduces the dimensionality of the agent’s exploration space to speed up the training convergence rate.

Firstly, the decay weight function is set in the objective function of the agent’s training to combine both types of methods, and both RL and imitation learning (IL) are considered to guide the agent's behavior when updating the policy. Second, this study designs a coupling utilization method between the demonstration trajectory and the training experience, so that samples from both aspects can be combined during the agent’s learning process, and the utilization rate of the data and the agent’s learning speed can be improved.

The method is superior to other algorithms in terms of convergence speed and decision stability, avoiding training from scratch for reward values, and breaking through the restrictions brought by demonstration data.

The agent can adapt to dynamic scenes through exploration and trial-and-error mechanisms based on the experience of demonstrating trajectories. The demonstration data set used in IL and the experience samples obtained in the process of RL are coupled and used to improve the data utilization efficiency and the generalization ability of the agent.

Mega construction projects (MCPs), which play an important role in the economy, society and environment of a country, have developed rapidly in recent years. However, due to frequent social conflicts caused by the negative social impact of MCPs, social risk control has become a major challenge. Exploring the relationship between social risk factors and social risk from the perspective of risk evolution and identifying key factors contribute to social risk control; but few studies have paid enough attention to this. Therefore, this study aims to systematically analyze the impact of social risk factors on social risk based on a social risk evolution path.

This study proposed a social risk evolution path for MCPs explaining how social risk occurs and develops with the impact of social risk factors. To further analyze the impact quantitatively, a social risk analysis model combining structural equation model (SEM) with Bayesian network (BN) was developed. SEM was used to verify the relationship in the social risk evolution path. BN was applied to identify key social risk factors and predict the probabilities of social risk, quantitatively. The feasibility of the proposed model was verified by the case of water conservancy projects.

The results show that negative impact on residents’ living standards, public opinion advantage and emergency management ability were key social risk factors through sensitivity analysis. Then, scenario analysis simulated the risk probability results with the impact of different states of these key factors to obtain management strategies.

This study creatively proposes a social risk evolution path describing the dynamic interaction of the social risk and first applies the hybrid SEM–BN method in the social risk analysis for MCPs to explore effective risk control strategies. This study can facilitate the understanding of social risk from the perspective of risk evolution and provide decision-making support for the government coping with social risk in the implementation of MCPs.

The main cause of aseptic inflammation after an in vivo implantation is that Poly(L-lactide) (PLLA) and Poly(D-lactide) have a slower degradation and absorption rate, while Poly(D, L-lactide) (PDLLA) has a much faster degradation rate than PLLA because of its amorphous structure. Also, the hydrolyzate of Hydroxyapatite (HA) is alkaline, which can neutralize local tissue peracid caused by hydrolysis of Polylactic acid.

In this study, the selective laser sintering (SLS) technique was chosen to prepare bone scaffolds using nano-HA/PDLLA composite microspheres, which were prepared by the solid-in-oil-in-water (S/O/W) method. First, the SLS parameters range of bulk was determined by the result of a single-layer experiment and the optimized parameters were then obtained by the orthogonal experiment. The tensile property, hydrophobicity, biocompatibility, biological toxicity and in vitro degradation of the samples with optimized SLS parameters were characterized.

As a result, the samples showed a lower tensile strength because of the many holes in their interior, which was conducive to better cell adhesion and nutrient transport. In addition, the samples retained their inherent properties after SLS and the hydrophobicity was improved after adding nano-HA because of the OH group. Furthermore, the samples showed good biocompatibility with the large number of cells adhering to the material through pseudopods and there was no significant difference between the pure PDLLA and 10% HA/PDLLA in terms of biological toxicity. Finally, the degradation rate of the composites could be tailored by the amount of nano-HA.

This study combined the S/O/W and SLS technique and provides a theoretical future basis for the preparation of drug-loaded microsphere scaffolds through SLS using HA/PDLLA composites.

Semi-crystalline polymers such as polyamide-12 can be used for selective laser sintering (SLS) to make near-fully dense plastic parts. At present, however, the types of semi-crystalline polymers suitable for SLS are critically limited. Therefore, the purpose of this paper is to investigate the processibility of a new kind of semi-crystalline polypropylene (PP) with low isotacticity for SLS process.

The SLS processibility of the PP powder, including particle size and shape, sintering window, degree of crystallinity and degradation temperature, was evaluated. Effects of the applied laser energy density on the surface micromorphology, density, tensile strength and thermal properties of SLS-built PP specimens were studied.

The results show that the PP powder has a nearly spherical shape, smooth surfaces, an appropriate average particle size of 63.6 μm, a broad sintering window of 21 oC and low crystalline degree of 30.4 per cent comparable to that of polyamide-12, a high degradation temperature of 381.8°C and low part bed temperature of 105°C, indicating a very good SLS processibility. The density and the tensile strength first increase with increasing laser energy density until they reach the maximum values of 0.831 g/cm3 and 19.9 MPa, respectively, at the laser energy density of 0.0458 J/mm², and then decrease when the applied laser energy density continue to increase owing to the degradation of PP powders. The complex PP components have been manufactured by SLS using the optimum parameters, which are strong enough to be directly used as functional parts.

This paper provides a new knowledge for this field that low-isotacticity PPs exhibit good SLS processibility, therefore increasing material types and broadening the application of SLS technology.

This paper aims to tackle the challenge topic of continuum structural layout in the presence of random loads and to develop an efficient robust method.

An innovative robust topology optimization approach for continuum structures with random applied loads is reported. Simultaneous minimization of the expectation and the variance of the structural compliance is performed. Uncertain load vectors are dealt with by using additional uncertain pseudo random load vectors. The sensitivity information of the robust objective function is obtained approximately by using the Taylor expansion technique. The design problem is solved using bi-directional evolutionary structural optimization method with the derived sensitivity numbers.

The numerical examples show the significant topological changes of the robust solutions compared with the equivalent deterministic solutions.

A simple yet efficient robust topology optimization approach for continuum structures with random applied loads is developed. The computational time scales linearly with the number of applied loads with uncertainty, which is very efficient when compared with Monte Carlo-based optimization method.

This paper aims to present a method of color three-dimensional (3D) printing based on color adherence.

First, experiments of the color effects of 3D printings using different carriers and different printing methods were performed. Second, the color of a specific point could be calculated through a theory of dimension-reducing, and the color distribution of 3D model was transformed from 3D to 1D color line corresponding with 3D print sequence. At last, the color lines, which were printed on a PE film by silk-screen printing, was carried by a filament and then printed through a fused deposition modeling 3D printer.

The printing ink and PE film are suitable as the pigment and carrier under this investigation, respectively. Based on an idea of reducing dimension, the method of 3D color printing through adhering color to a filament is realized. The color saturation of the sample was relatively high through the method.

It is hard to avoid that there may be some residual color in the nozzle through this method, and the purity of following color will be affected. As a result, continuous improvements should be made to perfect the method.

An approach of 3D color printing is described in detail, and what kind of model is more applicable is discussed particularly.

This approach is implemented to print color 3D objects with just one nozzle by means of color adherence. That is, printing the 3D objects using the filament is carried out with 1D color line, which is printed by a traditional printing method.