Display omitted
•Data system of aqueous BrC was improved.•The optical properties of aqueous BrC were regular.•The research results can provide some experimental basis for atmospheric and climate ...models.
Brown carbon (BrC) can absorb solar radiation in the ultraviolet (UV) and near visible (Vis) regions, which plays an important role in the Earth’s radiative balance and global climate. 1,4-dioxane-2,5-diol (DD), glyoxal (GX) and acetaldehyde (AAld) appeared moderate absorbent and fluorescent, when each of them reaction with glycine (Gly)/ammonium sulfate (AS). Combined with the previous experimental studies of the methylglyoxal (MG), GX reaction with GX/AS, novelty conclusions are as following: the absorbance of the reaction products in the same reaction time followed the order: MG-Gly＞DD-Gly＞GX-Gly＞AAld-Gly, DD-AS＞MG-AS＞GX-AS＞AAld-AS. And for the same aldehyde compound reaction with Gly the reaction rate was faster than with AS. Three-dimensional excitation-emission matrix (EEM) plot showed that, with the increasing of reaction time, red shift of emission peak occurred in MG-Gly/AS and GX-Gly, no shift occurred in DD-Gly/AS and AAld-Gly, and blue shift occurred in GX-AS. The H2O2 oxidation photolysis results showed that the effective H2O2 oxidation photolysis rate constants (k) in the visible region are larger than in UV region for the reaction MG, GX, DD with Gly. But for AAld-Gly system, the k in the visible region is smaller than in the UV region. Besides, the reaction MG, GX, DD, AAld with Gly clearly showed that the presence of abundant organic products by Liquid chromatography/mass spectrometry (LC/MS) analysis.
PurposeThis research aims to propose a comparative environmental analysis of conventional and prefabricated construction techniques utilizing a building information modelling (BIM) ...technique.Design/methodology/approachA set of indicators are selected to assess the environmental emissions throughout the construction life cycle, based on BIM platform. An existing project involving ten apartment buildings in Shanghai is selected as a case study.FindingsThe results reveal that prefabricated construction demonstrates environment-friendly performance with some exceptions of acidification and mineral resource consumption. Environmental impacts can also be further reduced by increasing the projected area ratio and percentage of project prefabrication.Originality/valueOverall, the proposed method can be used to identify relevant environmental merits and for decision-making of appropriate construction techniques in building construction projects.
Covalent organic frameworks (COFs) are a new class of functional solids featuring several fantastic structural characteristics, including a great diversity of building units and cross-linking ...patterns, precise integration of building blocks, and adjustable topology of porous architecture. In addition to the above features, some COF samples are constructed with high-density conjugated fragments, which have unique potential advantages in fluorescence imaging, and thus may have great potential applications in bioimaging. Herein, this article summarizes the recent progress in the design and preparation of fluorescent covalent organic frameworks. We investigate the systemic correlation between the structural qualities of COF networks and biological sensors. Finally, the significant advantages, major challenges, and future opportunities of fluorescent covalent organic frameworks are discussed for the development of next-generation porous materials for sensing applications.
Aluminum alloy is widely used in high˗speed train bodies. However, compared with the base material, the tensile strength and elongation of its laser welded joints are significantly reduced, which ...limits the lightweight application of the next generation of high˗speed trains. The research in this article indicates that laser welding with Ca micro˗alloyed 5356 filler metal has changed the mechanical properties and microstructure of the weld seam. Without the Ca in the filler metal, the strength and elongation of the laser welded joint are only 215.5 MPa and 3.1 %. When the Ca content in the filler metal reaches 0.04 wt%, the laser welded joint has high tensile strength and maximum elongation, which are 251.5 MPa and 9.7 %, respectively. As the Ca content increases, the grain size of the welded joint gradually decreases, and the limiting effect of Ca element on the growth of α˗Al grains is the main reason for grain refinement. In addition, the addition of Ca transforms the coarse Fe˗rich phase in the weld into a fine˗grained second phase, while promoting the formation of deformable nanoparticles γ˗Al12Mg17, leading to the accumulation of dislocations and successfully improving the strength and plasticity of laser welded joints. When the Ca content further increases, the second phase grows, and the tensile strength and plasticity of the joint slightly decrease, but are still higher than that of the joint without Ca.
False rumors can lead to huge economic losses or/and social instability. Hence, mitigating the impact of bogus rumors is of primary importance. This paper focuses on the problem of how to suppress a ...false rumor by use of the truth. Based on a set of rational hypotheses and a novel rumor-truth mixed spreading model, the effectiveness and cost of a rumor-containing strategy are quantified, respectively. On this basis, the original problem is modeled as a constrained optimization problem (the RC model), in which the independent variable and the objective function represent a rumor-containing strategy and the effectiveness of a rumor-containing strategy, respectively. The goal of the optimization problem is to find the most effective rumor-containing strategy subject to a limited rumor-containing budget. Some optimal rumor-containing strategies are given by solving their respective RC models. The influence of different factors on the highest cost effectiveness of a RC model is illuminated through computer experiments. The results obtained are instructive to develop effective rumor-containing strategies.
•The issue of suppressing a false rumor by use of the truth is addressed.•A rumor-truth mixed spreading model is proposed.•The original problem is modeled as an optimization problem.•Some optimal rumor-containing strategies are derived.•The influence of different factors on the highest cost effectiveness is uncovered.
Bone infections caused by bacteria during bone graft implantations can impair the ability of bone tissue repair, which is currently a clinical problem. In this study, the electrospinning technique ...was used to prepare a polylactic acid (PLLA)/silver (Ag) composite fiber, in which the silver nanoparticles (Ag-NPs) were uniformly distributed on the inner surface of PLLA fibers; dopamine (DA) was self-polymerized on the composite fiber surface to construct the adhesive polydopamine (PDA) film and chitosan (CS) was used to regulate Ag+ in situ through pulse electrochemical deposition for the construction of a stable Ag-NPs coating (CS/Ag), achieving the steady and slow release of Ag-NPs, therefore accomplishing the construction of a “inside-outside” Ag-NPs-loaded PLLA/Ag@PDA@CS/Ag composite fiber with dual functions of long-lasting antibacterial effect as well as bone regeneration promotion ability. The study results showed that the composite fiber has an excellent antibacterial effect against E. coli and S. aureus, and good osteoinductive and angiogenic properties. In summary, under the dual regulations of the strong adhesion of PDA and CS chelation, the “inside-outside” Ag-NPs-loaded composite fiber was endowed with good physiological stability, long-term antibacterial effect and bone infection inhibition ability, making it a promising bone implant material.
Display omitted
•Electrospinning technology and pulse electrochemical deposition technology for fabricating composite fiber•Dual regulations of the strong adhesion of PDA and CS chelation•Inside-outside silver nanoparticles-loaded composite fiber•Good physiological stability and long-term antibacterial effect•Capability in promoting osteoinduction differentiation and angiogenesis
Abstract
This study aimed to investigate the relationship between exercise addiction and brain structure in middle-older individuals, and to examine the role of self-efficacy in mediating ...physiological changes associated with exercise addiction. A total of 133 patients exhibiting symptoms of exercise addiction were recruited for this study (male = 43, age 52.86 ± 11.78 years). Structural magnetic resonance imaging and behavioral assessments were administered to assess the study population. Voxel-based morphological analysis was conducted using SPM12 software. Mediation analysis was employed to explore the potential neuropsychological mechanism of self-efficacy in relation to exercise addiction. The findings revealed a positive correlation between exercise addiction and gray matter volume in the right inferior temporal region and the right hippocampus. Conversely, there was a negative correlation with gray matter volume in the left Rolandic operculum. Self-efficacy was found to indirectly influence exercise addiction by affecting right inferior temporal region gray matter volume and acted as a mediating variable in the relationship between the gray matter volume of right inferior temporal region and exercise addiction. In summary, this study elucidates the link between exercise addiction and brain structure among middle-older individuals. It uncovers the intricate interplay among exercise addiction, brain structure, and psychological factors. These findings enhance our comprehension of exercise addiction and offer valuable insights for the development of interventions and treatments.
•Porosity is a critical defect in aluminum alloys during laser welding.•Mg element has an important effect on the stability of laser welding process.•Mg element promotes the molten filler wire to ...transfer to keyhole.•Molten droplets flow down the front wall of the keyhole and connect with the protrusion of the rear wall, resulting in the collapse of the keyhole.
Porosity is a critical defect in aluminum alloys during laser welding. In this study, three filler wires with different Mg content were used to study the effect of Mg on the porosity formation in laser wire filling welding. The increase of Mg content of filler wire leads to the increase of recoil pressure and decrease the surface tension of keyhole wall, which promotes the molten filler wire with more Mg content to transfer to keyhole. The molten droplets flow down the front wall of the keyhole and connect with the protrusion of the rear wall, resulting in the collapse of the keyhole. Therefore, the porosity is more likely to occur in the laser welding with higher Mg content filler wire.
Compared with traditional onsite construction, prefabricated construction has a more complex working environment, resulting in more safety risks. While cognitive failure has been identified as a ...primary cause of intentional unsafe behaviors, there remains a lack of knowledge on the formation mechanism underlying intentional unsafe behaviors among workers in precast construction. Using the Theory of Planned Behavior and the risk preference variable, this study constructs a theoretical model for intentional unsafe behaviors of precast construction workers. Data related to precast construction and safety management activities is collected from 208 frontline workers. Structural Equation Modeling is used to test and modify the theoretical model in order to identify the formation mechanism and pathway underlying intentional unsafe behaviors. The findings show that: (1) workers’ perceptual behavior control, behavior and attitude, risk preference, and subjective norms influence their intention to engage in unsafe behavior and subsequently lead to intentional unsafe behavior; (2) the effect of personal risk preference on intentional unsafe behaviors is significant, contributing 7.71% to overall intentional unsafe behavior; and (3) the effects of the observed variables are more evident than the initial theoretical model. The most prominent of these are the effects of task intensity (IBC1), safety equipment (IBC2), worker behavior (IOW1), historical behavior (IBC3), and behavioral belief (BAA3). Finally, comprehensive measures to control the intentional unsafe behaviors of precast construction workers are recommended. The results of this study are useful for reducing the occurrence of intentional unsafe behaviors by workers and reducing the incidence of accidents in a complex manufacturing-oriented construction environment.
Chinese herbal medicine (CHM) evolved through thousands of years of practice and was popular not only among the Chinese population, but also most countries in the world.
(L.) DC. as a traditional ...treatment for wound healing in Li Nationality Medicine has a long history of nearly 2000 years. This study was to evaluate the effects of total flavonoids from
(L.) DC. on skin excisional wound on the back of Sprague-Dawley rats, reveal its chemical constitution, and postulate its action mechanism. The rats were divided into five groups and the model groups were treated with 30% glycerol, the positive control groups with Jing Wan Hong (JWH) ointment, and three treatment groups with high dose (2.52 g·kg
), medium dose (1.26 g·kg
), and low dose (0.63 g·kg
) of total flavonoids from
. During 10 consecutive days of treatment, the therapeutic effects of rates were evaluated. On day 1, day 3, day 5, day 7, and day 10 after treatment, skin samples were taken from all the rats for further study. Significant increases of granulation tissue, fibroblast, and capillary vessel proliferation were observed at day 7 in the high dose and positive control groups, compared with the model group, with the method of 4% paraformaldehyde for histopathological examination and immunofluorescence staining. To reveal the action mechanisms of total flavonoids on wound healing, the levels of CD68, vascular endothelial growth factor (VEGF), transforming growth factor-
₁ (TGF-
₁), and hydroxyproline were measured at different days. Results showed that total flavonoids had significant effects on rat skin excisional wound healing compared with controls, especially high dose ones (
< 0.05). Furthermore, the total flavonoid extract was investigated phytochemically, and twenty-seven compounds were identified from the total flavonoid sample by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry/diode array detector (UPLC-Q-TOF-MS/DAD), including 16 flavonoid aglucons, five flavonoid glycosides (main peaks in chromatogram), five chlorogenic acid analogs, and 1 coumarin. Reports show that flavonoid glycoside possesses therapeutic effects of curing wounds by inducing neovascularization, and chlorogenic acid also has anti-inflammatory and wound healing activities; we postulated that all the ingredients in total flavonoids sample maybe exert a synergetic effect on wound curing. Accompanied with detection of four growth factors, the upregulation of these key growth factors may be the mechanism of therapeutic activities of total flavonoids. The present study confirmed undoubtedly that flavonoids were the main active constituents that contribute to excisional wound healing, and suggested its action mechanism of improving expression levels of growth factors at different healing phases.
PDF
