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Chitosan (CS) is the only natural alkaline polysaccharide originated from deacetylation of chitin that is the main component of shell from marine organisms. It has great potential medical application due to its broad-spectrum antimicrobial activity and good water solubility originated from its protonated amino groups under acidic condition and abundant hydroxyl groups. However, unprotonated NH2 group of CS leads to its poor solubility under physiological condition and limits its diverse applications. Therefore, it is highly necessary to summarize the modification strategies of CS derivatives systematically to help researchers select the most appropriate strategies for their specific applications. Herein, we have summarized the modification strategies of CS derivatives for improving their antimicrobial activity, water solubility, biocompatibility, and mechanical property by chemical reaction and physical integration. And then we have reviewed the CS derivatives in hydrogels, nanoparticles, or coatings for medical application in wound dressing, drug delivery, medical implant. Last but not the least, we have put forward the future perspectives of deep studies about structure-activity relationship and clinical applications of CS derivatives.

In presented research work, high energy planetary ball milling process was employed to prepare different types of organic and inorganic particles by dry pulverization. The agricultural fibrous waste (i.e. Agave Americana, cornhusk, jute) was utilized to prepare organic particulate fillers whereas the wastes of basalt, carbon, glass and fly ash were utilized to prepare inorganic particles. The particles were then incorporated at 3 wt% loading into epoxy resin, and their properties were investigated for improvement in dynamic mechanical and creep behavior of epoxy composites.

The overall number of drug abuse cases has been on the rise around the world, causing it a disaster in many countries. In this retrospective study, we analyzed the characteristics of 11,903 drug abuse cases in Beijing, the capital of China, in the perspective of age, gender, nationality, region, season, type of specimens and various drugs, respectively. The case information was collected by the national-level forensic toxicology laboratory, which belongs to the China University of Political Science and Law. It was shown that the overall number of drug abuse cases had increased sharply from 2018 to 2019 and had a decrease of 25% in 2020. The incidence of drug abuse cases involving men was much higher than that of the cases involving women. The adolescents and young adults accounted for the largest share of drug abusers in our study. Haidian, as a national center of scientific and technological innovation with global influence, had the largest percentage of toxic substance-related cases, and the change was more pronounced than other districts during the 3-year-period. Chaoyang was second to Haidian in the number toxic substance-related cases. As a key window of economic, Chaoyang had the highest number of foreigner drug cases. June to August had the highest number of drug abuse cases, while amphetamines, opioids, cannabis and cocaine were the most common toxic substances involved in the cases we detected. To our knowledge, this is the first study to provide an overall analysis of drug abuse cases in Beijing, China. The study indicated the presence of a wide number of drug abuse cases in the capital city and confirmed the threat for the public safety and health. Such forensic information can assist the government to devise intelligence-based preventive and repressive measures and policies.

Recycled aggregate has emerged expecting to address raw materials shortage in construction sector by converting waste concrete into resource. Many researchers adopted life cycle assessment (LCA) to evaluate and compare environmental impact of recycled aggregate concrete (RAC) and natural aggregate concrete (NAC). However, there are numbers of problems in applying the LCA in RAC, a unified treatment of the subject is still lacking. By reviewing existing corresponding literature, this paper identified the existing problems of applying the LCA method in RAC from 5 aspects, including mixture design method, selection of functional units, allocation of inventory, CO2 uptake during the life cycle of concrete and transport distance of recycled aggregate. Review results indicate that when analyzing the environmental impact of RAC by LCA, a clear indication of the mixture design methods of RAC should be given at first. Second, a benchmark method to define the functional unit of the LCA of RAC is urgently needed to make different LCA studies comparable. A method that combining the effect of quality, mass and market price on the allocation procedure of recycled aggregate should be further investigated. Besides, ignoring CO2 uptake in the use stage of RAC will lead to an overestimated CO2 emission of RAC. In addition, a critical distance for recycled aggregate is existed when comparing the environmental impact between NAC and RAC. At last, some contents of recycled aggregate concrete for further research have been proposed.

Se-enriched green tea has been widely used as a functional food and disease prevention. In this study, two kinds of homogeneous polysaccharides namely ASe-TPS2 and NSe-TPS2 were obtained from artificial and natural Se-enriched teas with the molecular weights of 6.73 × 103 Da and 2.44 × 105 Da. The structures of ASe-TPS2 and NSe-TPS2 were characterized by monosaccharide composition analysis, partial acid hydrolysis, methylation, FT-IR spectroscopy, NMR spectroscopy, SEM and TGA analysis. It showed that ASe-TPS2 and NSe-TPS2 were acidic polysaccharides containing high amount of uronic acid. The structure of the ASe-TPS2 was mainly composed of β‑D‑(1 → 3)‑Glcp, α‑D‑(1 → 4)‑GalpA, (1 → 4)‑Glcp, α‑L‑(1 → 2)‑Rhap and α‑D‑(1 → 4)‑GalpA, and the non-reducing ends were mainly composed of Araf and Xylp. However, the NSe-TPS2 was mainly composed of β‑D-(1 → 4)‑Glcp and α‑D‑(1 → 4)-GalpA, and the branches were mainly composed of β‑L‑(1 → 2)‑Araf, α‑D‑(1 → 3)‑Galp and β‑L‑(1 → 2)‑Rhap whereas the non-reducing ends were mainly composed of Glcp and Galp residues. These results suggested that the distinction of selenylation methods could present different polysaccharide chain structures.

Using supplementary cementitious materials (SCMs) in concrete is considered as one of the possible solutions to making green concrete. Previous research often analyzed the environmental impact of concrete without considering the influences of compressive strength and durability simultaneously. Such a practice will lead to less rational life cycle assessment (LCA) results, since the service life of concrete could be shortened when durability is poor, especially if concrete is exposed to marine dry-wet environment where chloride ion is intensive. Moreover, Fick’s second law of diffusion was always used to determine the chloride diffusion coefficient of concrete, without considering the influences of convection zone and peak value of chloride concentration. Therefore, this paper proposed an integrated functional unit combining durability (resistance to chloride ion diffusion), compressive strength and volume to evaluate the environmental impact of concrete containing SCMs. The chloride diffusion coefficient was calculated by re-scaling the ‘‘zero’’ of penetration axis to calibrate Fick’s second law of diffusion. In addition, three other functional units (volume, combining volume and compressive strength, combing volume and durability) were also proposed and compared. Results indicate that the selection of functional unit has a significant influence on the LCA results of the studied concrete. Despite the variation with different functional units, concrete containing silica fume or silica fume as well as fly ash shows a consistently superior environmental performance over the ordinary concrete.

Exponential damping is an improved version of the viscous damping model and better represent energy dissipation character of actual structures. This study aims at verifying the applicability of the exponential damping model for concrete structures and the accuracy of model parameter identification methods. In this paper, the dynamic tests are conducted on a series of reinforced concrete cantilever beams to obtain frequency response functions. The obtained results show that the exponential damping model can better reflect the energy dissipation capacity of concrete components, especially in the high frequency vibration modal. The recently proposed identification method based on FEM updating for the exponential damping system can predict accurately not only natural frequencies but also the FRFs of concrete beams. The research of the exponential damping will increase the accuracy and efficiency of dynamic behavior analysis of actual concrete structures.

China has about 60 billion m2 of existing buildings, with approximately 2 billion m2 newly constructed each year. This accounts for half of all new buildings globally. A large number of buildings were demolished during the urban renewal process in China, significantly reducing the average lifespan of buildings and wasting vast amounts of energy and resources. However, the corresponding environmental impacts of reduced building lifespans have not been studied. Moreover, how to accurately evaluate future environmental impacts of construction projects is still a difficult problem, since in some cases the environmental impacts may not be realized for many years. In order to investigate the relationship between building lifespans and the corresponding environmental impacts, this paper first estimated the average lifespan of buildings in China through literature review, field investigation and calculation (using survival rate and demolition rate, respectively), revealing that the average building lifespan in China is from 25 to 35 years which is far shorter than the designed lifespans of buildings in China. It is also much shorter compared to the building lifespans in ten developed countries. Six buildings in Hebei Province in China were selected as case studies to conduct life cycle environmental (LCE) impact assessment. The results of the case studies indicate that (1) extending the building's lifespan from 30 to 50 years would reduce 40% of its total LCE impacts; (2) the environmental impacts caused by buildings (per area per year) in China is 2.3 times than that in the UK; (3) when environmental impacts are considered over time, they would decrease dramatically with the increase of discount rate, indicating that the buildings in developed cities in China with higher discount rates are more sensitive to environmental degradation.

Se-containing polysaccharide is known to Se-conjugated macromolecule, with potent bioactivities due to the synergistic effects of Se and native polysaccharide. It is not only explored as a novel Se source in dietary supplement, but also as the superb bioactive component owning various functions, including antioxidant, antitumor, immune-enhancement, hepatoprotective, antidiabetic, anti-inflammatory and neuroprotective activities. Se-containing polysaccharide can exert the efficacy of Se and polysaccharide, and its activities are much higher than those of Se or polysaccharide. In the last decades, numerous reports on Se-containing polysaccharide (including natural Se-containing polysaccharide and selenylated polysaccharide) appeared in literature. For the first time, this article systematically introduces recent advances on preparation, structural characterization and bioactivities of Se-containing polysaccharide in details, and discusses its future prospects and the weaknesses in the current study.

Converting natural resources into electricity is an essential part of the transition to sustainable energy generation. Evaporation-driven moist-electric generators (EMEGs) are an emergent technology and show great potential for harvesting clean energy. In this paper, we report a flexible textile EMEG based on the decoration of an asymmetric micro-nano hierarchical capillary system on the cotton fabric. When water droplets encounter this textile EMEG, the water flows spontaneously under capillary action without requiring an external power supply, resulting in a constant generation of voltages up to 0.65 V and currents up to 8 μA on a small piece of sample with size of 2 cm × 5.5 cm × 0.2 mm (0.16 mL of water can induce a constant electric output for more than 3600 s). More importantly, even when fully wetted or totally immersed in water, the EMEG can maintain its electrical output owing to its inherent electrochemical asymmetry. Furthermore, the output can be enhanced by integrating multiple units, generating sufficient power to drive LED devices, while the energy can also be stored in supercapacitors. This study is of high value for designing of versatile electric generator to harvest clean energy constantly.

Protease has been widely used in biological and industrial fields. Developing efficient artificial enzyme mimics remains a major technical challenge due to the high stability of peptide bonds. Nanoenzymes with high stability, high activity and low cost, provided new opportunities to break through natural enzyme inherent limitations. However, compared with many nanomaterials with inherent peroxidase activity, the intrinsic mimic proteases properties of magnetic nanomaterials were seldom explored, let alone the interaction between magnetic nanomaterials and cellular proteins. Herein, we reported for the first time that magnetic CuFe2O4 possesses inherent protease activity to hydrolyze bovine serum albumin (BSA) and casein under physiological conditions, and the CuFe2O4 is more resistant to high temperature than the natural trypsin. It also exhibited significantly higher catalytic efficiency than other copper nanomaterials and can be recycled for many times. Protease participated in pathophysiological processes and all stages of tumor progression. Interesting, CuFe2O4 exhibited anti-proliferative effect on A549, SKOV3, HT-29, BABL-3T3 and HUVEC cells, as well as it was particularly sensitive against SKOV3 cells. CuFe2O4 was about 30 times more effective than conventional chemotherapy drugs oxaliplatin and artesunate against SKOV3 cells. In addition, CuFe2O4 also mediated the expression of intracellular proteins, such as MMP-2, MMP-9, F-actin, and NF-kB, which may be associated with global protein hydrolysis by CuFe2O4, leading to inhibition of cell migration. The merits of the high magnetic properties, good protease-mimic and antitumor activities make CuFe2O4 nanoparticles very prospective candidates for many applications such as proteomics and biotechnology.

So far, the poor stability of Cu2O is still the major challenge in heterogeneous catalysis. Herein, Bougainvillea glabra (B. glabra) derived carbon supported copper composite (Cu2O/BGC) was synthesized in situ by one-pot pyrolysis method. In the synthetic strategy, B. glabra was used as reductant and carbon source simultaneously, and copper nitrate as copper precursor. Cu2O/BGC exhibited a significant enhancement in both catalytic activity and stability for cyclohexane oxidation with tert-butyl hydroperoxide as oxidant under solvent-free condition. Cu2O/BGC with a Cu/C ratio of 0.8 calcined at 800 °C showed the highest catalytic cyclohexane conversion efficiency (77.1%) and cyclohexanone selectivity (68.5%). Its turnover number (TON) is 12.2- and 1.3-fold compared to pure Cu2O and Cu2O/BGC prepared by deposition-reduction method, respectively. Hot filtration experiment confirmed that the sample was a heterogeneous catalyst which could be reused five times without losing its activity.

In China, rapid and continuing infrastructure growth will significantly affect the feasibility of achieving CO2 emission reduction targets. It is uncertain whether the current infrastructure designs are consistent with the national emission targets of China, consequently posing a threat to the national commitment to reaching carbon neutrality. To illustrate the gap in achieving the emission targets with respect to bridges, we present carbon intensity reduction targets relevant to bridges by 2040. By exploring three policy–economic scenarios that combine with CO2 emission reduction policy scenarios of the International Energy Agency and shared socioeconomic pathways, we assess the adaptability of the bridge designs to short-, medium- and long-term carbon intensity targets. We propose a new sustainability design approach based on a bridge big data set that integrates reliability, environmental impacts, and cost. We show that, under the current policy–economic scenario, more than 50% of code-based bridges would meet the five-year CO2 emission target, whereas only one in ten thousand could meet the ten-year target under the new policy–economic scenario. Under the sustainable development policy–economic scenario, none of the bridge designs would meet the carbon reduction targets over the next 20 years. Our findings highlight that the bridges in China need to be duly considered in setting CO2 reduction targets, and in the national move toward zero carbon, careful consideration should be given to implementing our proposed bridge sustainability design.

The performance of disposable face masks in blocking pathogenic microbes mainly relies on the ability of melt-blown fabrics to electrostatically adsorb air droplets. While their easy invalidity in electrostatic effect highly limits their use recyclability, leading to a heavy burden on the surrounding environment due to their decomposing difficulty. Thus, it is urgent to develop reusable air filtration fabrics. In this work, we report a washable electret air-filtering fabrics with negligible cytotoxicity by combining spontaneous polarizing photochromic molecule with electrospinning electret technology. The electrostatic charge and filtration efficiency of the composite fabrics were highly improved compared to the commercial polypropylene melt-blown fabrics. Moreover, due to its electrostatic charge induced by self-polarization, the photochromic Spiropyran(SP)/polystyrene(PS) electret fabrics can maintain high filtration performance (over 95%) towards PM0.3 particles and low air flow resistance (

The traditional construction industry is characterized as a labor-intensive, wasteful, and inefficient sector. Currently, prefabrication has become a common practice in residential development and has reduced energy consumption and waste generation compared to traditional on-site practices. This study investigates the differences in life cycle environmental impacts among three different floor systems (precast slab, composite slab (semi-precast slab) and cast-in-situ slab) based on two functional units (delivering the same carrying capacity and maintaining consistent floor depth) using both LCA midpoint and endpoint methods using the software tool SimaPro. This study sets a calculation boundary for the construction process: raw material production, slab production, transportation, construction activities on-site, demolition and recycling of buildings at the end-of-life stage. Moreover, uncertainty and sensitivity analysis are carried out to help decision-makers identify major environmental impact factors and develop eco-friendly plans to facilitate housing industrialization. The results indicate that (1) the environmental impact of precast slab outperforms those of cast-in-situ and composite floors regardless of different design functional units and evaluation methods. (2) While under different functional units, the environmental performance of composite and cast-in-situ floors varies considerably. (3) From the perspective of life cycle stages, the transportation sector and its supply chain make up a significant portion of the final environmental impact and are responsible for 45.2%, 50.1% and 53.6% of the total impact for the precast, composite and cast-in-situ slabs, respectively. Slab production of precast slab (it is raw material production of cast-in-situ and composite slabs) is the second largest contributor to the environmental impact.

Maintenances are necessary to ensure the safety and serviceability of existing bridges. With the increasing number of existing bridges, maintenances cost a large proportion of financial fund and have significant impact on environment. Implementation of preventive maintenance (PM) could reduce the frequency of essential maintenance (EM) and corresponding cost, leading to considerably lower environmental impact of maintenances. Different from planning of EM, which depends on the structural condition of an existing bridge, PM is periodical. Selection of initial time and time interval of PM will influence the life cycle cost and environmental impact of existing bridges. In this study, a framework for the maintenance scheme optimization of existing bridges based on the genetic algorithm was proposed. Maximum safety, minimum life cycle cost and life cycle environmental impact were taken as optimization objects to find a more rational initial time and time interval of PM of the bridges. To verify the effectiveness of the proposed optimization procedure, a case bridge was selected and the cumulative failure probability, life cycle cost, and life cycle environmental impact of the case bridge with different maintenance schemes were calculated. An optimal maintenance schemes set of the case bridge was obtained. Comparison among the optimal schemes and the scheme without PM was conducted. It can be concluded that PM is of great importance on bridge management. Selection of the initial time and time interval of PM rationally would decrease the bridge's life cycle environmental impact effectively. The reduction of the life cycle cost of the bridge caused by maintenance scheme optimization is not significant. This is because that time value of cost was considered by introducing discount rate into the framework.

The creep-recovery behavior of both normal and high strength concrete (HSC) under various load conditions has not been studied thoroughly. Although the use of HSC is long-established, rational creep-recovery prediction of HSC is still unavailable since current study just regards recovery deformation as a secondary result of creep experiments. In this paper, a new prediction model for creep-recovery of normal strength concrete (NSC) with considering the influence of stress level and load history was proposed at first. Then, a model for HSC creep-recovery was established according to creep-recovery data of NSC and HSC in literatures and the influence of compressive strength of concrete. To validate the HSC model, an experimental study of the creep behavior of C80 concrete was conducted. Creep and residual strain after unloading of specimens at various compression stress levels (30% and 50% of the compression strength) were compared with the HSC creep-recovery model. Although the HSC model tends to underestimate the first 7 days’ creep-recovery value, the results show high overall prediction accuracy. Moreover, parametric analysis results indicate that the recoverable creep of HSC reduces significantly than that of NSC. The effect becomes stronger with the increase of loading age and weaker with a prolongation of load duration.

Concrete is one of the most widespread construction materials in the world, but its production is responsible for significant amounts of energy consumption, and even greater greenhouse gas emissions. However, the substitution of Portland cement with fly ash (FA) reduces both the energy consumption and the greenhouse gas emissions generated during the production of clinker. Currently, most studies of FA concrete focus on mechanical properties, sustainability assessments (environment, society and economy) of FA during its life cycle have not been reported. This paper presents a life cycle sustainability assessment (LCSA) that brings together environmental, economic and social impacts using a proposed three-dimensional coordinate diagram to combine the different units into a single sustainable value. The assessment method is applied to different substitutions of FA in concrete to ascertain the optimum substitution percentage across these three factors. Monte Carlo simulation is then used to evaluate the durability of concrete structures with different FA addition in order to calculate their service life. A case study is conducted of a bridge structure with different FA substitutions; this demonstrates that the addition of FA would improve the sustainability of concrete significantly in the short term. However, when the durability and service life of the structure are taken into account, without maintenance, the use of FA concrete may not improve the environment performance due a potentially shortened service life, but it can reduce the social burden and save costs significantly over the long term.

Diabetes and its related metabolic disorders are worldwide public health issues. Many studies have shown that changes in the structure and composition of the intestinal flora are closely related to the host's physiological and pathological processes. In this study, we aim to explore the effect of Liubao tea (LBT) extract on hyperglycemic mice with metabolic disorders and intestinal flora dysbiosis and to further study its regulatory effect on insulin resistance and its potential regulatory mechanism. Our results show that LBT had a good hypoglycemic effect and could significantly alleviate the metabolic disorder evoked by hyperglycemia. The gut microbial sequencing showed that LBT treatment increased the diversity of intestinal flora, increased the abundance of beneficial bacteria, and reduced the abundance of harmful or conditional pathogenic bacteria, as well as significantly altered 39 of the top 50 OTUs with abundance. Besides, LBT could activate the PI3K-Akt-PPARs-GLUT2 cascade signaling pathway to improve metabolic disorders, thereby alleviating insulin resistance. These results suggest that LBT has excellent potential to become a natural functional food for the prevention of hyperglycemia and insulin resistance.

Qingzhuan tea (QZT) with longer aging year is usually believed to have higher quality and commercial value. In this study, a 20 years sequence of aged QZT were subjected to an electronic tongue and liquid chromatography-mass spectrometry to investigate the effect of storage age on its metabolic profile and taste quality. The changes in both taste quality and metabolic profile exhibited a parabolic trend in the 20 years of QZT aging and reached the maximum at the 10th year. A total of 47 compounds were identified as critical metabolites responsible for the age variation of QZT quality, with the methylation of catechins, glycosylation of flavonoids, degradation of flavoalkaloids, biosynthesis of triterpenoids, and formation of theabrownins. These results suggested that the taste of QZT was improved after 10 years of storage, with the reduction of bitterness and astringency and a general increase of key quality-related compounds.

The chemical profile and taste quality of various dark teas vary considerably due to the huge differences in tea cultivar, processing technology, and production region. Herein, we integrated liquid chromatography-mass spectrometry and electronic tongue to reveal variations in chemical profile and taste quality of five typical dark teas, namely Pu-erh tea (PET), Fuzhuan tea (FZT), Qingzhuan tea (QZT), Kangzhuan tea (KZT), and Liubao tea (LBT), and elucidate chemical basis for their taste quality. The chemical phenotypes of dark teas were classified into FZT, PET, and QZT-KZT-LBT, whereas their taste phenotypes were classified into FZT, PET-QZT, and KZT-LBT. Totally, 49 compounds were identified as differential metabolites, with higher contents of catechins and flavonoid glycosides in FZT, and higher contents of catechin derivatives, flavonoids, and alkaloids in PET. PET had the strongest bitterness and aftertaste-bitterness, while FZT showed the strongest astringency, aftertaste-astringency, and saltiness among five typical dark teas. The bitterness and aftertaste-bitterness of dark teas were negatively associated with polyphenols, flavonoids, and polysaccharides, but positively associated with theabrownins; their aftertaste-astringency was positively related to polyphenols and flavonoids, but negatively related to theabrownins. This study will guide dark tea taste quality control and lay a foundation for comparing their health benefits.

Concrete is one of the most widely used materials in modern civil engineering construction. Concrete creep is traditionally defined to be a kind of time-dependent behavior exhibited by concrete under sustained constant loads. In this article, a new method is proposed to test the short-term creep of concrete and the deformation state after unloading process. The test results indicate that after loading, regardless of whether the constant load is sustained or not, the specimen exhibits a hysteretic recovery after unloading, which challenges the traditional definition of concrete creep. In addition, we first observed that the fundamental time-dependent strains of concrete, which can be separated from concrete creep under sustained load, could peak in several minutes and begin to fall. The long-term creep mainly results from unrecoverable deformation, which arises as the recoverable deformation is gradually transformed into unrecoverable deformation through micro-damage accumulation. The hysteretic recovery and time-dependent behaviors which were discovered reveal the fundamental viscoelastic origin of concrete creep.

Buildings consume large amounts of energy and resources and have a significant impact on environment. In 2010 buildings accounted for 32% of total global final energy use and 19% of energy-related GHG emissions. This energy use and related emissions may double or potentially even triple by mid-century. China is the world's largest energy consumer and CO2 emitter. With the process of urbanization, China has been entering into a period of great prosperity for construction, about 1.6–2.0 billion m2 buildings are constructed each year, which accounts for about 40% of the world's total new buildings. It is predicted that China’s building energy use and related emissions will continue to increase over the next 15 years. Therefore, promoting green building development has become an urgent issue in China. However, green building is a highly complicated system engineering, its promotion needs evaluation standards as technical support. Many countries had issued a series of green building evaluation standards since 1990. Currently, there are some representative green building assessment schemes. Code for Sustainable Homes (CSH) has been fully implemented as the national authoritative standard of the UK since 2010. Leadership in Energy and Environmental Design (LEED) developed by the USA, was revised and updated regularly with the latest version issued in 2013. China enacted its national evaluation standard for green building in 2006, and revised the standard in 2014. Based on introducing the latest evaluation standards for green buildings in China, Britain and United States, the paper compared these standards from 5 aspects including energy-saving, water-saving, material-saving, site selection and the outdoor and indoor environmental quality. The comparison mainly focuses on evaluation methods and evaluation indicators in the three standard systems. Besides, the characteristics of each standard system were summarized and some suggestions for improving China’s evaluation standard for green building were proposed.

In this study, a rapid sandwich immunochromatographic assay (ICA) was developed to detect parvalbumin (PV). Firstly, two optimum primary monoclonal antibody (mAb) against PV had been screened out: mAb1 was used as the capture antibody, and mAb2 conjugated to Fe3O4/Au nanoparticles (Fe3O4/AuNPs) that served as a detection reagent. Using this pair of mAbs, a sandwich ICA strip based on Fe3O4/AuNPs was developed. The results showed that the color intensity of test line positively correlated with the PV concentration in the standard or spiked sample. The limit of detection for qualitative (LOD) and quantitative detection (LOQ) were 2 ng/mL and 0.691 ng/mL, respectively. Besides, the detection time of this ICA strip was within 15 min. The recovery rates ranged from 104.0% to 117.4%, within an acceptable level (80–120%). Moreover, the developed assay also showed high cross reaction in different fish species. These results demonstrated that the established test strip has the potential to be used as a rapid screening tool for large scale determination of PV in foodstuffs.

The objective of present research was to study the Ohmic heating and mechanical stability of carbon fabric/green epoxy laminated composites after incorporation of 0.5, 1 and 3 wt % unmilled and milled fly ash particles. The Ohmic heating behavior was analyzed by estimating temperature response rapidity, maximum temperature, and electric power efficiency from time-temperature curves of the composites when constant voltage of 5 V was applied for the duration of 120 s. The composites filled with 0.5 wt % milled fly ash showed rapid heating, high temperature generation and less power consumption. Later, the effect of 15, 30 and 60 min Ohmic heating action on structural and mechanical stability of 0.5 wt % fly ash filled composites was examined from DSC, SEM, tensile testing, dynamic mechanical analysis and creep testing. The composites filled with milled fly ash showed superior mechanical and viscoelastic stability than unmilled fly ash composites. This indicated faster heat transportation characteristics by milled fly ash particles to avoid local matrix melting around carbon fibres during Ohmic heating. The marginal loss in mechanical properties was found due to increased agglomeration tendency of fly ash particles under Ohmic heating.

Creep and damping, which are two important static and dynamic properties of concrete material, have similar mechanical characteristics and have not been studied integratedly. This paper aims to develop a new method to investigate the creep and damping properties of recycled aggregate concrete (RAC) from viscoelastic perspective. In this research, a fractional order derivative viscoelastic creep model of RAC under different load levels was proposed. Then, with the consideration of recovery coefficient and time-dependent behavior, the damping properties of RAC based on interconversion between viscoelastic functions were investigated. The creep tests of reinforced RAC beams, accompanied by loading and unloading tests, were conducted to study the viscoelastic properties, meanwhile, free-vibration tests at different ages were carried out to analyze the time-dependent damping behavior of RAC. Test results indicate that compared with three parameter model and generalized three parameter model, fractional three parameter model is a feasible viscoelastic model to characterize both creep and damping behavior of RAC. The creep compliance of RAC is higher than that of NAC, and increases with the increasing of load level. The damping property of RAC decreases with the increasing of load frequency and the decreasing of load level, meanwhile, the damping property of RAC is related to recoverable instantaneous deformation. In addition, the damping property of RAC decreases with the increasing age when it is not considering load, but increases when it is subjected to sustained load. The proposed damping model was validated with a database of RAC damping in published literatures.

Buildings contribute 23 % of the total CO2 emissions produced by global economics activities, in which nearly 41 % are emitted by China. Carbon accounting is necessary to support an efficient low-carbon economic system. There is currently very little research on the carbon cost of buildings, especially in China. This article analyzes the carbon emissions generated during the life cycle of buildings, and transfers them to building environment cost and carbon cost. A life cycle building carbon cost accounting model was proposed under different carbon cost systems, including carbon trading system and carbon tax system. To verify the validity and reliability of the proposed model, the similarities and differences between carbon cost and carbon emission environmental damage cost determined by the Life-cycle Impact Assessment Method based on Endpoint Modeling (LIME) were compared. Carbon costs can link carbon reduction with economic benefits, and push the present policy-based mandatory reduction measures to market-based means, which is of great significance to sustainable development of the construction industry and China's future emission reduction targets.

Embedding of the functional materials into aerogel powders was realized via the filtration method. In this work, the effect of aerogel on the molecule structure of the embedded polyethylene glycol (PEG) was investigated by dispersing aerogel powders in 20 wt% PEG aqueous solution with subsequent filtration method. The encapsulation of the PEG in the aerogel was characterized by isothermal nitrogen (N2) adsorption/desorption. The structure of the embedded PEG in the aerogel powders was investigated via SEM-EDS, FE-SEM, FT-IR, XRD. TG-DTA, DSC, and leakage test. It was found that the only physical capillary force worked to adsorb PEG molecules from its solution by the aerogel powders. The BET surface area and the DFT pore volume of the PEG/aerogel powders were reduced obviously when compared with pure aerogel powders. The ability of the pores in the aerogel powders ranging from 14 nm to 16 nm to adsorbing the PEG molecules from the water system was weak. The crystallinity of the PEG was significantly reduced because of the limited space for crystal growth, and the decomposed temperature and thermal capacity decreased correspondingly.

Concrete creep and damping are related to reinforced concrete structural static and dynamic performance respectively. Comprehensive investigation of the fundamental behavior of concrete under dynamic and static loading is quite significant to material science of concrete. However, over more than a hundred years since concrete creep was found, it was seldom studied jointly with concrete damping. This paper analyzed the correlation between concrete damping and creep from the perspective of viscoelasticity. Firstly, concrete creep and damping tests under different loading rates were conducted to prove that the damping and creep characteristics of concrete are related to viscoelasticity of concrete. Secondly, in terms of theoretical calculation, a new conversion formula of concrete creep and damping was proposed based on viscoelastic theory. Comparison with experimental results shows that the proposed conversion formula is applicable to concrete.

Methcathinone metabolic profiles were meticulously evaluated in human blood (plasma), urine and hair samples. Ultrasound-assisted extraction with methanol was used to hair extraction, while solid-phase extraction (SPE) was applied to urine and blood (plasma) samples. Liquid chromatography-high field quadrupole exactive orbitrap mass spectrometer (LC-Q Exactive HF MS) was then applied to analyze the extracts. Full-scan positive-ion mode and the targeted MS/MS strategies were firstly employed to obtain precise mass measurements. Seventeen metabolites, including 14 phase I and 3 phase II metabolites, were characterized and preliminarily identified. In addition to methcathinone and cathinone, 15 unreported metabolites were identified initially. Six metabolic pathways, including demethylation, ketone reduction, glucuronidation, hydroxylation, acetylation and sulphation were also illuminated in this work, containing five novel metabolic pathways of methcathinone. Although methcathinone and cathinone are widely considered to be the primary biomarker, they were not detected in blood (plasma) samples. By comparing the contents and metabolic time points of these metabolites in different biological samples, it was determined that urine samples can serve as the preferred biological material for identifying methcathinone misuse. M4 (Demethylation + monohydroxlyation) was detected in all the biological samples, suggesting that it can potentially act as a new biomarker for monitoring methcathinone abuse.

Creep and sulfate erosion resistance of concrete are very important in terms of performance of concrete. It is of great interests to combine these two effects together to make a comprehensive investigation of the long-term performance of concrete. However, the research of the concrete creep under both dry-wet circulation and sulfate attack condition has rarely been reported. This paper firstly conducted experiments on the creep of concrete subjected to dry-wet cycle and sulfate attack. The test factors considered in this study include load stress level, sulfate solution concentration, immersion ways including long-term immersion (LM) and dry-wet cycle (DW). Then a creep model of concrete under sulfate corrosion was proposed considering concrete damage by mechanics theory, the prediction from the modified creep model is in good agreement with the test data. Taking into account the dry-wet cycles effects in the BP-KX model of concrete creep, the paper presented a model to predict the creep of concrete under dry-wet circulation and sulfate attack based on the creep model of concrete under sulfate corrosion. Finally, the calculated results from this new model were compared with the test data and the characteristics, shortage and applicability of this new model were also discussed.

In this paper, a full-factorial design of experiment was applied to thoroughly investigate the effects of compression ratio, intake valve closing retardation angle, and engine speed on the fuel consumption performance and power performance of the Miller cycle engine based on a quasi-dimensional simulation model. A new indirect analysis method based on formula derivation and main effect analysis was proposed to simplify the complex relationship between the design factors and the performance parameters. The definition of effective compression ratio was modified to take account of the actual mass of mixture trapped in the cylinder. The results show that the distributions of brake mean effective pressure and brake specific fuel consumption can be regarded as the re-organization results from the distributions of volumetric efficiency and indicated efficiency. The intake valve closing retardation angle has a strong negative correlation with volumetric efficiency. The modified effective compression ratio is the approximate product of the compression ratio and the volumetric efficiency, and makes obvious effects on the distribution of the indicated efficiency. Therefore the combustion process is co-evolved with the intake process in a Miller cycle engine. The further improvement of brake specific fuel consumption is mainly limited by four factors, i.e., the back flow loss, the exergy loss, the incomplete expansion loss, and the combustion loss. The improvement of fuel consumption performance is at a cost of power performance, and the trade-off between the both essentially results from the knock constraint. The engine speed makes obviously effects on both volumetric efficiency and indicated efficiency, resulting in increasing the nonlinearity of the variation of the performance parameters. However, the nonlinearity provides a possibility for a Miller cycle range extender to improve the fuel consumption performance and power performance at same time by optimizing the controlled speed.

The non-uniformly distributed material damping in single-layer latticed domes subjected to earthquake ground motions has been ignored in engineering practice, and the structural damping of bearings and joints has been modeled at a structural level in previous studies. In this paper, an explicit method for modeling the material damping and structural damping using a finite element method is proposed. The proposed method includes important characteristics for modeling single-layer latticed domes. The steel material damping is directly taken into account using Ramberg–Osgood material model (power-law) with hysteretic damping; the structural damping at bearings is modeled based on the bearing type. The ball joints of domes tend to be simplified as nodes in the finite element method without considering the actual geometric shapes and sizes of the balls for convenience. In this paper, the energy dissipation at joints and modeling methods for damping are proposed and discussed in terms of the joint type in domes. To illustrate the proposed method for computation, a typical single-layer latticed dome with base isolation bearings subjected to six near-fault earthquake ground motions is selected as an example. The dynamic demands of this single-layer latticed dome are analyzed using the simulation technology proposed in this paper. The effects of key parameters of the dome on the damping forces, which are of interest to many practitioners, are presented and discussed. Compared with the previous modeling methods for damping, the proposed method can model the damping effects of domes with a higher fidelity, which eliminates the unrealistically high forces generated with conventional modeling methods.

Although recycled aggregate concrete (RAC) has been studied intensively over past two decades, its damping property is still not analyzed sufficiently. In this paper, a nonlinear damping model for RAC prisms subjected to cyclic uniaxial compression are presented. Then with the combination of the compressive strength and damping property of RAC, an optimum recycled concrete aggregates (RCA) content including particle size and replacement percentage are recommended. The cyclic uniaxial compression test was conducted to investigate the dynamic modulus and nonlinear damping property of RAC, meanwhile tests for the RAC’s static compressive strength and modulus of elasticity were also carried out. Then based on the nonlinear damping model and compressive strength, relationships among the compressive strength, damping property, load indicators and RCA content are analyzed to obtain the optimum RCA content. Test results indicate that RAC obtains a higher loss factor than NAC. The loss factor of RAC is an increasing power function of RCA particle size and a decreasing power function of RCA replacement percentage. However, the compressive strength and dynamic modulus of RAC decreases compare with that of natural aggregate concrete. The different choice of cyclic uniaxial compression load indicators (cyclic stress range, stress level or strain range) has significance impact on RAC damping property and optimum RCA content.

Creep brings forth considerable influences on both static and dynamic behaviours of concrete structures. This paper intends to deepen the investigation on the creep influence on structural dynamic performance, evaluating their relationship from the view of reliability. The influencing mechanism of concrete creep on structural dynamic behaviour is first stated. Integration of the structural creep analysis by the Model B3 and the age-adjusted effective modulus method with the stochastic seismic analysis by the pseudo-excitation method is then proposed. Based on the creep-influenced structural static and stochastic seismic behaviours, formulations for the dynamic reliability with the consideration of creep effect are derived using the first-passage failure criterion and Poisson crossing assumption. A systematic numerical simulation is conducted on a long-span concrete filled steel tube arch bridge, considering (1) the creep influence on concrete mechanical properties and structural configuration and internal forces; (2) the dimensionality, wave passage effect and incoherence effect of random ground motions; and (3) the uncertainties existing in the structure and creep behaviour. Critical conclusions are drawn and it is recommended to consider the long-term effect of dead loads in seismic design to ensure structural seismic safety.

In order to classify typical Chinese tea varieties, Fourier transform infrared spectroscopy (FTIR) of tea polysaccharides (TPS) was used as an accurate and economical method. Partial least squares (PLS) modeling method along with a self-organizing map (SOM) neural network method was utilized due to the diversity and heterozygosis between teas. FTIR spectra results of tea extracts after spectra preprocessing were used as input data for PLS and SOM multivariate statistical analyses respectively. The predicted correlation coefficient of optimization PLS model was 0.9994, and root mean square error of calibration and cross-validation (RMSECV) was 0.03285. The features of PLS can be visualized in principal component (PC) space, contributing to discover correlation between different classes of spectra samples. After that, a data matrix consisted of the scores on the selected 3PCs computed by principle component analysis (PCA) and the characteristic spectrum data was used as inputs for training of SOM neural network. Compared with the PLS linear technique's recognition rate of 67% only, the correct recognition rate of the PLS-SOM as a non-linear classification algorithm to differentiate types of tea reaches up to 100%. And the models become reliable and provide a reasonable clustering of tea varieties.