Abstract ：

Heavy metals that are readily chelated with coexisting organic ligands in industrial wastewaters impose threats to environment and human health but are also valuable metal resources. Traditional treatment methods generally require additional chemicals and generate secondary contaminants. Here, a reagent-free dual-cathode electrochemical system was proposed for the efficient destruction of Cu-organic complexes and synchronous cathodic recovery of Cu, whereby in situ production of H2O2 at carbon aerogel (CA) cathode was coupled with the reduction of Cu(II) to Cu(I) and finally to Cu(0) at Ti cathode. The intermediate Cu(II) complexes enabled the self-reinforced degradation owing to their higher activities toward •OH generation by activating H2O2 in contrast to initial Cu-ethylenediaminetetraacetic acid (Cu-EDTA). The enhanced production of Cu(I) by Ti cathode facilitated both •OH and Cu(III) formation, and the copper redox cycle was realized in the self-reinforced system, maintaining its sustainable catalytic activity. The energy cost of the dual-cathode system is 0.011 kWh/g for decomplexation and 0.057 kWh/g for Cu recovery, which is much lower than single Ti or CA cathode system. This established process provides a prospective approach for cost-effective destruction of chelating metal complexes and metal resources recovery from heavy metal wastewaters. © 2024

Keyword ：

Heavy metals Chelation Doping (additives) Redox reactions Energy efficiency Metal recovery Bioremediation

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Abstract ：

Urban waterlogging poses a severe threat to lives and property globally, making it crucial to identify the distribution of urban value and waterlogging risk. Previous research has overlooked the heterogeneity of value and risk in spatial distribution. To identify the overlay effect of urban land value and risk, this study employs the Entropy Weighting Method (EM) to assess urban value, Principal Component Analysis (PCA) to determine waterlogging risk and key areas (RK), local Moran's I (SC) to identify key areas (HK), and finally Bivariate local Moran's I (DC) to comprehensively evaluate urban value and waterlogging risk to delineate key areas (BH). The results indicate that waterlogging risk is primarily influenced by proximity to water systems (PCA coefficient: 0.567), population density (0.550), and rainfall (0.445). There is a positive correlation between urban value and waterlogging risk, with a global Moran's I of 0.536, indicating that areas with higher urban value also face greater waterlogging risk. The DC method improved identification precision, reducing the BH area by 6.42 and 3.51 km2 compared to RK and HK, accounting for 25.50 % and 15.76 % of the RK and HK identified areas, respectively. At present, rescue resources can access less than one-third of the area within 5 min, but with the DC method, during the centennial rainfall scenario, the accessibility rate within 5 min for the BH area reaches 63 %, and all BH key areas can be covered within 15 min. This study provides a new methodology for identifying key areas of waterlogging disasters and can be used to enhance urban rescue efficiency and the precision management of flood disasters.

Keyword ：

Land use value Bivariate spatial autocorrelation Value -risk overlay Risk assessment Urban waterlogging

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Abstract ：

Blue laser with high power and high beam quality has many applications such as in laser display, underwater communication and imaging, and non-ferrous metal processing. Optically pumped external -cavity surface -emitting laser combines the advantages of both surface -emitting semiconductor lasers and solid-state disk lasers, and can produce high output power and good beam quality simultaneously. Its high intracavity circulating power is more conducive to intracavity frequency doubling, achieving high -power and high beam quality blue light through fundamental laser in the near -infrared waveband. This paper reports an efficient intracavity frequency doubled 490 nm high power blue light by using a 980 nm fundamental laser in an external -cavity surface -emitting laser. The V -type resonant cavity is formed by the high reflectivity distributed Bragg reflector (DBR) at the bottom of gain chip, a folded flat concave mirror (high reflectivity coated for 980 nm and anti -reflectivity coated for 490 nm), and a flat concave end mirror (high reflectivity coated for 980 nm and 490 nm). By inserting a nonlinear crystal LBO into the cavity at the beam waist formed by the folded mirror and end mirror, and employing a birefringent filter (BRF) to polarize the fundamental laser and narrow the linewidth of the laser, a high power and high beam quality blue laser with high conversion efficiency is obtained. The effects of different factors including the length of nonlinear crystal, the linewidth of fundamental laser, and the compensation of walk off angle on the output power of the blue laser are studied experimentally. The length of the nonlinear crystal is optimized based on the size of the fundamental laser beam waist at the position of the crystal in the resonant cavity. Under the type -I phase matching condition of LBO, over 6 W output power at 491 nm wavelength is obtained when the crystal length is 5 mm and the BRF thickness is 1 mm. The beam quality M2 factor in the x direction and the y direction are both 1.08, and the conversion efficiency of frequency doubling is 63%. The experimental results also show that symmetrically placed nonlinear crystals can compensate for the walk -off angle during frequency doubling to a certain extent, thereby clearly improving the conversion efficiency of the frequency doubled blue laser.

Keyword ：

compensation of walk off angle intracavity frequency-doubled type-I phase matching external-cavity surface-emitting blue laser

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As one of the most important topics studied in creep fracture mechanics, mechanics fields at 3D sharp V-notch front tip in creeping solids have drawn remarkable attention at present. In this paper, the higher-order asymptotic analysis is carried out for 3D sharp V-notch front tip fields in creeping solids subjected to mode I loading, and a 3D higher-order term solution is theoretically proposed by introducing the out-of-plane stress factor Tz to establish the 3D nonlinear governing equations of front tip fields. The present higher-order asymptotic solution for 3D sharp V-notch can naturally be degenerated to that for 3D crack. It is found that the stress exponents and angular distribution functions of higher-order terms for 3D notch and crack are highly related to Tz. The proposed 3D higher-order term solution overall shows better agreement with the FEA results than the existing 3D leading-term solution and 2D higher-order term solutions available in the literature, especially for smaller notch angle and shorter ligament lengths. Based on the 3D higherorder asymptotic solution, a new fracture parameter AT2 is given and combined with Tz to characterize 3D constraint effect. It is noted that the effects of AT2 and Tz on 3D constraint are highly interlinked rather than simply separated into in-plane and out-of-plane parts. The present 3D higher-order asymptotic solution can promote the understanding and characterization of 3D constraint effect and is of great significance in the evaluation of 3D fracture behavior and structural failure assessment under creep conditions.

Keyword ：

Creeping solid 3D crack Higher-order asymptotic solution Constraint effect 3D V-notch

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Long-term high sugar accelerates skin ageing via glycosylation. In this study, microalgae-derived active compounds were investigated for their potentially beneficial effects on skin ageing. Two carotenoids, namely astaxanthin (in the form of either monoester or diester) and lutein, were separated from the green alga Haematococcus pluvialis. These carotenoid fractions significantly attenuated the high glucose (HG)-induced cell injury and oxidative stress. They also inhibited the formation of N epsilon-Carboxymethyllysine (CML), a typical product of glycosylation. The degradation of collagen I and III caused by HG was substantially recovered, in which astaxanthin monoester exhibited the most prominent effect. This was attributed to the down-regulation of matrix metalloproteinase (MMP)-2 mRNA expression. Through proteomics analyses, six hub proteins were identified, which work as highly connected nodes in the protective effects of astaxanthin monoester against HG stress. These findings strongly suggest the benefits of microalgae-derived carotenoids in alleviating HG-induced skin ageing.

Keyword ：

Haematococcus pluvialis Collagen degradation Astaxanthin esters Glycosylation Lutein

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Abstract ：

High-speed rotation instruments that apply gradient hypergravities can induce local variations in structure and thus induce cracking. Rotation-induced hypergravity is a kind of gradient force, and it has a gradient value that depends on distance and local weight. Conventional mechanical testing applies a constant force or periodic force instead of true gradient hypergravity to rotating components. In this study, a dedicated instrument was designed and assembled, and a special sample of 1060 aluminium slats with multiple thinned necks was used to reveal the difference between gradient hypergravity and conventional constant forces. Hypergravity caused more significant damage to the aluminium slat, and the ultimate crack strength was approximately 10% of the strength observed under the constant force applied at the same temperature. All the samples cracked on the inner neck which bears the highest hypergravity. Two types of cracks were categorized based on the relative extension: type I mode cracks occurred in the centre of the neck with long extension before cracking under hypergravity more than 3.5 MPa, while type II cracks occurred in the root of the neck without long extension before cracking under hypergravity less than 3.5 MPa. Combination of hypergravity and torsional force in high-speed rotation system prompt cracking and exhibit similar microstructure with that under high constant force. Typical cracking and its microstructure under the effects of hypergravity and temperature provided a convenient and practicable method for evaluating service safety of commercial rotating machines for industrial applications and raw alloys.

Keyword ：

Microstructure Hypergravity Cracking Aluminium

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Establishing the correlation between damage recovery and temperature in nuclear materials is vital to understanding material property degradation. Among the handful of topics related, one long-standing concern is the differences in damage recovery caused by different initial defect concentrations, with respect to ranges below and beyond the damage saturation limit. In this study, the temperature dependence of damage recovery has been comprehensively elucidated for pure tungsten, irradiated with 6 MeV copper ions at room temperature (RT), up to 0.05 dpa (non-saturated damage, n-SD) and 0.6 dpa (saturated damage, SD), and followed by isochronal annealing. Coupled transmission electron microscopy and Doppler broadening positron annihilation spectroscopy characterizations provided a full-probe-range picture of defect evolution. The varied initial defect concentrations caused retaining differences in damage recovery, but no substantial influence on temperaturedependent defect evolution. Moderate and dramatic damage recovery were identified below 973 K and above 1123 K in n-SD and SD tungsten, respectively. Most strikingly, nano-sized voids were confirmed at 473 K in both samples. Annealing at 1873 K saw the complete removal of defects in n-SD tungsten, but survival of a few dislocations via void pinning in SD tungsten. Full damage recovery in SD tungsten was projected to be similar to 2000 K. The current revisit of damage recovery stages demonstrated the significance of encompassing scenarios of nonsaturated and saturated defect concentrations. Accordingly, four damage recovery stages were redefined for heavy-ion irradiated tungsten, namely stage I (20 K- RT), stage II (RT- 653 K), stage III (653- 1123 K), and stage IV (1123- 2000 K).

Keyword ：

Heavy-ion irradiation Non-saturated and saturated displacement demage Tungsten Damage recovery stages Defect evolution and recovery

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Iodinated aromatic disinfection byproducts have attracted much attention owing to their high toxicity. However, little has been known about the iodination mechanism to date. In this study, the iodination of model aromatic precursors, tyrosine (Tyr) and its model dipeptides, by HOI and other iodinating agents was explored using a quantum chemical computational method, and the halogenation of Tyr by HOX (X = Cl, Br, and I) was compared. The results indicate that the phenolate salt plays a key role in the iodination of the phenol ring in Tyr compounds by HOI via the classic SEAr mechanism and the second deprotonation becomes the rate-limiting step, which explains why the kinetic isotope effect (KIE) was observed in the iodination of aromatic compounds. Among the seven possible iodinating agents present in chloramination, HOI is the predominant one, and I2 is the second in the iodination of the phenol ring under typical chloramination conditions. In the further investigation of bromination and chlorination, the KIE was found to also occur in the bromination of Tyr. More importantly, the different reactivity orders of HOX reacting with the phenol ring and the amino group in Tyr are related to the hardness of both HOX and substrates, which can be evaluated from the energy gap (ELUMO-HOMO) between the LUMO and HOMO energies. Following the "like-attracts-like" principle, the halogenating agent prefers the substrate with a similar ELUMO-HOMO value. The results are helpful in further understanding the iodination mechanism and identifying various halogenated products. The iodination mechanism of Tyr compounds by HOI and other iodinating agents was studied using the DFT method, and the halogenation of Tyr by HOX (X = Cl, Br, and I) was compared.

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Negative stiffness element has been applied to improve the control performance of tuned mass dampers (TMDs) recently, and two tuned mass dampers enhanced with negative stiffness (TMDNS) element, namely KDamper (Without loss of generality, it is referred to as TMD-NS I in the present study) and Extended KDamper (EKD, TMD-NS II), have been developed. Previous studies have demonstrated the control effectiveness of TMD-NS I and II. However, there still exist some issues to be addressed: (1) previous studies normally optimize TMD-NS via the intricate and timeconsuming numerical methods, the analytical solutions for the optimal design parameters of TMD-NS II remain unknown; (2) a comprehensive and exhaustive evaluation that compares the control effectiveness of TMD-NS I and II is absent from existing literature. To fill these research gaps, this study derives closed-form optimum solutions for TMD-NS II using the H infinity approach. The control effectiveness of TMD-NS I and II in suppressing the seismic responses of structures is investigated systematically. Specifically, the analytical model of an undamped SDOF system equipped with TMD-NS I or II is first developed within a unified framework, and corresponding dynamic equations of motion are formulated. Subsequently, the optimal parameters of TMD-NS I and II are derived based on the classical "fixed-point" theory. Based on the derived optimal parameters, the control effectiveness of TMD-NS I and II are examined by using a damped SDOF system subjected to harmonic excitations and real earthquake ground motions. Finally, a 5-storey isolated benchmark building model is adopted to further investigate the effectiveness of TMD-NS in the seismic protection of engineering structures. The results reveal that the derived closed-form solutions are accurate in capturing the optimal parameters of TMD-NS. In addition, both the optimized TMD-NS I and II outperform the conventional TMD in reducing the seismic responses of structures. Furthermore, TMD-NS I proves more effective in reducing the absolute acceleration of the isolated building, whereas TMD-NS II demonstrates better performance in mitigating the isolating deformation. In a nutshell, both the TMD-NS I and II are highly effective alternatives to conventional TMDs, showcasing superior performance in vibration reduction and robustness.

Keyword ：

Extended KDamper KDamper Closed-form optimum solutions Isolated structures Control effectiveness

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This paper analyzes the damping dissipation of damped outrigger tall buildings with inerter and negative stiffness considering soil-structure-interaction (SSI). A unified characteristic equation is established concerning different soil conditions and outrigger systems. By solving the unified characteristic equation, the multi-mode damping effect are parametrically investigated to evaluate the influence of SSI on tall buildings installing conventional outrigger (CO), conventional damped outrigger (CDO), negative stiffness damped outrigger (NSDO), and inerter damped outrigger (IDO). Then, the vibration performances of damped outrigger systems considering SSI are evaluated under both wind and earthquake loadings. Two key points are highlighted: (i) the interaction between the soil rocking behavior and the outrigger rotation in tall buildings; (ii) the influence of frequency variation caused by SSI on the damping effect of IDO and NSDO with frequency-dependent/independent features. Analyzing results indicate that a stronger CO would increase the damping effect of the foundation soil as long as the CO is not installed at lower stories. The SSI effect will render CDO itself undergo more dissipation for the first mode but limit CDO's damping effect on higher modes. IDO can be effective for the target mode, but is very sensitive to SSI effect due to its frequency-dependent feature; a re-optimization of IDO to proper vibration mode is always needed in resisting wind and earthquake. In contrast, NSDO's damping effect is less sensitive to the SSI effect and can be effective to multiple modes due to its frequency-independent feature. For example, the majority of the input energy from winds (over 90%) and earthquake (over 70 %) will be dissipated by NSDO, and such high values change little under SSI conditions, validating NSDO can provide effective and robust control to multiple hazards.

Keyword ：

Winds & earthquake mitigation Inerter absorbers Soil-structure-interaction Negative stiffness Tall buildings Damped outrigger Complex frequency analysis

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