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The hysteretic damping tuned mass damper (HD-TMD), which exhibits linear damping force, has been achieved by variable friction devices. Such devices own the advantages of stable mitigation capacity and easy maintenance compared to viscous damping devices. Previous studies have mainly concentrated on the vibration mitigation effect of the HD-TMD system without explicit consideration of structural acceleration control. In this context, seismic optimizations of HD-TMD for structural acceleration control were presented, and the effective damping of HD-TMD was investigated. H∞ optimizations of the HD-TMD were considered for undamped and lightly damped structures with fixed-point theory, where the closed-form solutions of optimal and improved parameters were derived. Parametric analysis for the dynamic amplification factors (DAFs) of structural acceleration revealed that the closed-form solutions effectively tuned the DAF into double peaks and reduced the maximum response overall frequency. H2 optimizations were conducted with residue theory for the optimization of the undamped structure, and the optimal parameters of HD-TMD subjected to stochastic ground excitation were obtained by numerical searching and curve-fitting techniques. Effective damping of the HD-TMD was consequently examined using the stochastic stationary process in which the damping effect additionally provided to the structure was measured. The effectiveness of the proposed optimal solutions for the HD-TMD in the form of an available engineering variable friction device was thereby corroborated by twenty sets of seismic ground motions. Spectrum's results indicated that the proposed optimal parameters greatly improved the absolute structural acceleration response and provided excellent seismic mitigation capacity for structural displacement response. The response of the equivalent SDOF demonstrated almost the same trend of absolute structural acceleration reduction, which revealed the successful application of effective damping of HD-TMD for designers. Detailed analysis of the earthquake record indicated the functionality and effectiveness of the proposed methods of HD-TMD with the average absolute structural acceleration reduction ratio of 65.86% and 42.66% for maximum reduction and standard deviation reduction, respectively. [ABSTRACT FROM AUTHOR]

• The nonlinear behavior of the PTMD with different damping is fully described. • Damping nonlinearity and stiffness nonlinearity of structure-PTMDs system are illustrated. • The attenuation characteristics of the PTMDs are obtained with closed-form expressions. • Nonlinear performance oriented optimization is based on amplitude robustness. • The optimization achieves an enlarged damping dissipation capacity of PTMD with HD. The inherent nonlinearity of the pendulum motion becomes increasingly pronounced as excitation amplitudes rise, leading to the uncertainty of vibration and the loss of predictive accuracy owing to the linear assumption. To address this concern, this study introduces the pendulum tuned mass damper (PTMD) with hysteretic damping (HD) to realize the nonlinear performance oriented optimal seismic design. The primary contribution of this study is introducing the nonlinear performance of the PTMD with HD, thereby proposing amplitude robustness optimization based on nonlinear dynamic performance. Theoretical configurations of PTMD that facilitate different types of damping, including viscous damping (VD), constant damping, and hysteretic damping (HD), are compared. The Krylov–Bogoliubov (K–B) method is originally adopted to analyze the nonlinear effect of the PTMDs in the case of forced oscillation and free vibration. The nonlinear frequency response functions (FRFs) of the structure-PTMD system are derived, and the coupled systems are evaluated. The presence of stiffness softening, the persistence of stable solutions, and the occurrence of unstable frequency response loops demonstrate the inherent nonlinearity and sensitivity of control effectiveness. Attenuation characteristics of the PTMDs are obtained to determine the damping dissipation properties with accuracy compared with the dynamic solutions. Prue HD shows a similar dynamic interaction with an exponential decay in damping dissipation as the VD, which exhibits the linear damping performance for the coupled control system. A nonlinear performance oriented optimal seismic design based on the amplitude robustness index is proposed to consider the amplitude uncertainty impact on the structure-PTMD system. A case study is assessed based on the 20-story benchmark structure to investigate the functionality of the proposed optimization for the PTMD with HD. The results confirm the effectiveness of optimization from the perspective of FRFs, where the optimal PTMD with HD exhibited an FRF with a lower peak in structural amplitude compared to the optimal PTMD with VD. Seismic validations of the spectral analysis and specific earthquake evaluations verify the applicability of the proposed optimization for PTMD with HD, enabling an enlarged damping dissipation capacity as earthquake excitation increases to provide better structural protection. [Display omitted] [ABSTRACT FROM AUTHOR]

Flexible high-rise buildings are extremely vulnerable to wind, especially when synchronously subjected to alongwind and crosswind forces. In this scenario, acceleration-sensitive targets (such as delicate instruments) are at risk of damage. Moreover, occupant comfort and structural safety may be degraded due to excessive bi-directional vibrations. To resolve this problem, a bi-directional rail variable friction pendulum-tuned mass damper (BRVFP-TMD) is used to achieve optimal bi-directional wind-induced vibration control. The modeling of the BRVFP-TMD for bi-directional high-rise buildings under bi-directional winds was performed. Further, the physical interaction forces of the BRVFP-TMD with a multi-degree-of-freedom structure and the governing equations for the modal structure with the BRVFP-TMD were derived, with experimental results confirming the effectiveness of the linear variable friction force. For the BRVFP-TMD with a lightly damped structure, acceleration optimizations were conducted to obtain closed-form solutions for optimal parameters. However, the deployment position of the tuned mass damper (TMD) was found to degrade the optimal control performance significantly. Therefore, for the convenience of engineers, improved optimal solutions were obtained by considering the actual deployment position of the TMD and the influence of inherent structural damping. The stochastic linearization method was used to evaluate the effect of linear hysteretic damping (HD) with equivalent viscous damping (VD) in the field of random theory. Accordingly, a closed-form expression for the VD ratio was proposed to represent HD. Numerical verifications of a Chinese landmark (Canton Tower) subjected to bi-directional winds were assessed through time history and frequency decomposition analyses. The results verified the effectiveness, correctness, and necessity of the BRVFP-TMD; the improved optimal solutions were also confirmed. Compared with the closed-form solution, which neglects the deployment position of the TMD, and the classic TMD, the improved optimal solutions of the BRVFP-TMD demonstrated superior performance in mitigating both structural displacement and acceleration. The vibration reduction ratios achieved were 44.55% for the displacement at the top of the mast and 46.69% for the acceleration at the top of the main tower. • The constitutive relation of BRVFP-TMD equipped with MDOF structure is provided. • Closed-form solutions for optimal acceleration control of BRVFP-TMD are obtained. • Improved optimal solutions of BRVFP-TMD considering deploy position are acquired. • SLM is verified by MCS to illustrate the connection between VD and HD. • Closed-form expression of equivalent VD ratio to represent HD ratio is obtained. [ABSTRACT FROM AUTHOR]

• A new two-dimensional anionic metal-organic framework (K-Zn-MOF) was synthesized by one-step solvothermal method. • K-Zn-MOF exhibited high adsorption capacity towards Sr2+ (q m = 878.3 mg/g). • K-Zn-MOF exhibited ultrafast kinetics for Sr2+ with 95.39% at an equilibrium time of 60 min. • The adsorption mechanisms include ion exchange and coordination adsorption. Efficient removal of radioactive 90Sr from solutions is of vital importance due to its radioactive nature and high mobility. Herein, a 2D anionic metal-organic framework (MOF) [Me 2 NH 2 ][KZn(pydc) 2 (H 2 O) 2 ]∙H 2 O (K-Zn-MOF; pydc = 2,6-pyridinedicarboxylic acid) was synthesized and characterized. The prepared K-Zn-MOF was in turn applied for the removal of Sr2+ ions and various experimental conditions including contact time, initial concentration, and temperatures were optimized. Experimental findings revealed that the adsorption of Sr2+ on K-Zn-MOF reached equilibrium within 60 min at room temperature with R e = 95.39%. K-Zn-MOF exhibited ultra-high adsorption capacity (878.3 mg g−1), remarkable affinity (K d = 5.8 × 105 mL g−1) in solutions and super-high selectivity in the presence of interfering coexisting ions (Na+, K+, Mg2+, and Ca2+). Mechanistic investigation suggested that free exchangeable [Me 2 NH 2 ]+ ions and strong interactions between uncoordinated oxygens from COO− groups with target ions significantly contributed to the rapid adsorption of Sr2+ ions. A 2-D anionic layer structure containing [Me 2 NH 2 ] + ions by the simple solvothermal reaction were obtained, denoted as K-Zn-MOF. Systematic studies revealed that K-Zn-MOF was an efficient ion exchanger material for the selective capture of Sr2+ ions. [Display omitted] [ABSTRACT FROM AUTHOR]

The impact of wind speed on PV power generation is influenced by the monsoon and the complex topography and environmental factors found in mountainous areas. This complexity can reduce the correlation between PV power and irradiance. To better understand the impact of wind speed, we conducted an analysis in various topographical regions of the Hengduan Mountain in China. Our findings show that high wind speeds can enhance PV utilization, particularly in plateau and hill regions. This is due to the blocking and lifting effect of the north-south oriented mountains on the east-west wind, as well as the channeling effect on the north-south wind. To improve the efficiency of utilizing solar energy, it is important to consider the spatial distribution of wind speed when developing PV. Correlation analysis of multi-factors on a spatial and temporal scale can also offer insight. Furthermore, planning the layout of PV systems with meteorological resources in mind can enhance PV utilization in complex mountainous terrain. [ABSTRACT FROM AUTHOR]

• Pendulum tuned mass damper (PTMD) with geometric nonlinear dampers (GND) is proposed. • Nonlinear behavior of the PTMD with GND characterized by the "unavailable" points. • The stochastic linearization method is adopted to simplify the nonlinear model. • Closed-form solution and optimal design procedure are built for the PTMD with GND. • The optimal design provides significant reduction by the dynamic damping mechanism. In engineering applications, the geometric nonlinear (GN) arrangement of pendulum-tuned mass dampers (PTMDs) may induce the damping force to deviate from its intended state. Therefore, this study extends the scope of the structural control strategy by introducing a pendulum-tuned mass damper considering geometric nonlinear dampers (GND). Specifically, the damper developed in this study, termed PTMD with GND, is an inconspicuous pendulum-type tuned mass damper with different GN settings in the initial state. A nonlinear mathematical model of the PTMD with GND is developed, identifying its significant nonlinear characteristics, particularly the "unavailable" locations. The stochastic linearization method (SLM) is adopted to simplify the nonlinear model using the Kanai-Tajimi modified spectrum. The SLM agrees well with the numerical results obtained using the Monte Carlo simulation method. Furthermore, the control strategy of PTMD with GND is proposed with the consideration of filtered random excitation. Several numerical cases have been conducted to investigate the availability of PTMD with GND and the proposed optimal design strategy under 178 real seismic excitations. The results show that the PTMD with GND is nearly as effective as the ideal transitional TMD in mitigating the seismic response of the primary structure and more effective than the inverted rough linear adjustment. It can be concluded that the proposed optimal design strategy for the PTMDs with GND efficiently suppressed the structural vibration through multiple performance indices and used the nonlinearity of the damping mechanism of the GND to provide a sufficient damping energy dissipation effect adaptively. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Changes in the key flavor substances were elucidated during broad bean fermentation. • The core microorganisms during the fermentation process were identified. • The pathways and mechanisms for forming the key flavor substances were established. Pixian Douban (PXDB) is a popular Chinese condiment for its distinctive flavor. Broad bean fermentation (Meju) is the most important process in the formation of flavor substances. Key flavors were analyzed qualitatively and quantitatively, and metagenomic technology was applied to study the microbial diversity during broad bean fermentation. In addition, the main metabolic pathways of key flavors were explored. Results indicated that Staphylococcus_gallinarum was the main microorganism in the microbial community, accounting for 39.13%, followed by Lactobacillus_agilis , accounting for 13.76%. Aspergillus_flavus was the fungus with the highest species abundance, accounting for 3.02%. The KEGG Pathway enrichment analysis showed that carbohydrate metabolism and amino acid metabolism were the main metabolic pathways. Glycoside hydrolase and glycosyltransferase genes were the most abundant, accounting for more than 70% of the total number of active enzyme genes. A total of 113 enzymes related to key flavors and 39 microorganisms corresponding to enzymes were annotated. And Staphylococcus_gallinarum, Lactobacillus_agilis, Weissella_confusa, Pediococcus_acidilactici, Staphylococcus_kloosii, Aspergillus_oryzae, and Aspergillus_flavus played a key role in the metabolic pathway. This study reveals the formation mechanism of key flavors in fermented broad bean, it is important for guiding the industrial production of PXDB and improving product quality. [ABSTRACT FROM AUTHOR]

Sterol regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) is a widely expressed membrane glycoprotein that acts as an important modulator of lipid metabolism and inflammatory stress. N-glycosylation of SCAP has been suggested to modulate cancer development, but its role in nonalcoholic steatohepatitis (NASH) is poorly understood. In this study, the N-glycosylation of SCAP was analyzed by using sequential trypsin proteolysis and glycosidase treatment. The liver cell lines expressing wild-type and N-glycosylation sites mutated SCAP were constructed to investigate the N-glycosylation role of SCAP in regulating inflammation and lipid accumulation as well as the underlying mechanisms. The hepatic SCAP protein levels were significantly increased in C57BL/6J mice fed with Western diet and sugar water (WD + SW) and diabetic db/db mice, which exhibited typical liver steatosis and inflammation accompanied with hyperglycemia. In vitro, the enhanced N-glycosylation by high glucose increased the protein stability of SCAP and hence increased its total protein levels, whereas the ablation of N-glycosylation significantly decreased SCAP protein stability and alleviated lipid accumulation and inflammation in hepatic cell lines. Mechanistically, SCAP N-glycosylation increased not only the SREBP-1-mediated acetyl-CoA synthetase 2 (ACSS2) transcription but also the AMPK-mediated S659 phosphorylation of ACCS2 protein, causing the enhanced ACSS2 levels in nucleus and hence increasing the histone H3K27 acetylation (H3K27ac), which is a key epigenetic modification associated with NASH. Modulating ACSS2 expression or its location in the nuclear abolished the effects of SCAP N-glycosylation on H3K27ac and lipid accumulation and inflammation. In conclusion, SCAP N-glycosylation aggravates inflammation and lipid accumulation through enhancing ACSS2-mediated H3K27ac in hepatocytes. NEW & NOTEWORTHY:N-glycosylation of SCAP exacerbates inflammation and lipid accumulation in hepatocytes through ACSS2-mediated H3K27ac. Our data suggest that SCAP N-glycosylation plays a key role in regulating histone H3K27 acetylation and targeting SCAP N-glycosylation may be a new strategy for treating nonalcoholic steatohepatitis (NASH). [ABSTRACT FROM AUTHOR]

The self-calibrating sensor based on Tb/Eu-MOF-6 exhibits visual colorimetric sensing for anthrax biomarker: fluorescent color changes from yellow to red after adding DPA. [Display omitted] Bacillus anthracis is toxic bacterial spore that cause human anthrax infections. Therefore, rapid and sensitive detection of Bacillus anthracis or its main biomarker 2, 6-pyridine dicarboxylic acid (DPA) is of great significance. Herein, a series of lanthanide–organic frameworks (Tb/Eu-MOF - 1 – 6) were synthesized by the solvothermal reactions of 2,2′-bipyridine-6,6′-dicarboxylic acid (H 2 BPDC) with Eu3+ and Tb3+. Among these samples, Tb/Eu-MOF-6 exhibited selective detection of DPA with self-calibrating and colorimetric fluorescence determination. The sensitivity of Tb/Eu-MOF-6 revealed a linear response of ln (I N) = -10.896C DPA + 0.14366 with a limit of detection with 4.51 μM. The emission color of Tb/Eu-MOF-6 observed with the naked eye, turned yellow to red after introducing appropriate concentration of DPA. The energy-transfer behavior between BPDC2- Tb3+, and Eu3+ was systematically studied, which primarily controlled the sensitivity of detection. With the combined merits of self-calibrating, rapid and naked-eye recognition of DPA, Tb/Eu-MOF-6 can be counted as a promising contender for anthrax biomarker detection. [ABSTRACT FROM AUTHOR]

In the realm of electronic circuits, materials with high thermal conductivity are sought after as ideal packaging components. It is crucial that such materials not only possess excellent thermal conductivity, but also maintain desirable dielectric properties. To this end, boron nitride nanosheets (BNNS) and BNNS/nanodiamond (ND) aerogels with a three‐dimensional (3D) structure using the ice‐template method were prepared. Subsequently, these aerogels were utilized as a framework to produce 3D‐BNNS/epoxy and 3D‐BNNS/ND/epoxy composites via the vacuum‐assisted impregnation method, which exhibit enhanced anisotropic thermal conductivity. Furthermore, the thermal conductivity exhibited by the 3D‐BNNS/epoxy composites outperforms those containing randomly distributed BNNS. The experiment also reveals sintering the aerogel at elevated temperatures to remove the PVA can significantly improve the thermal conductivity exhibited by the 3D‐BNNS/epoxy and 3D‐BNNS/ND/epoxy composites. Importantly, the 3D‐BNNS/ND/epoxy composites illustrate exceptional thermal conductivity values of 1.326 W/(m·K), indicating a remarkable synergistic effect of BNNS and ND in improving thermal conductivity. It is noteworthy to state that the relative thermal conductivity ratio of the 3D‐BNNS/epoxy and 3D‐BNNS/ND/epoxy composites to pure epoxy resin was markedly higher at lower temperatures than the values measured at room temperature, signifying their superior heat transfer performance at lower temperatures. In addition, the composites depict excellent dielectric properties and lower coefficients of thermal expansion values. Finally, the 3D‐BNNS/ND/epoxy composites also have significantly improved Tg (132.5 and 152.6°C). The high‐performance polymer composites described in this study are envisaged for implementation within the realm of electronic packaging materials. [ABSTRACT FROM AUTHOR]

The inner doubly iterative efficient algorithm (IDEAL), an advanced fully implicit algorithm for solving the pressure-velocity coupling problem, lacks a comprehensive implementation procedure on commonly used collocated unstructured grids. Therefore, this study provides a thorough demonstration of the fundamental principles, solving procedures, discretizations of momentum and pressure equations, Rhie-Chow interpolation implementation, mass continuity processing, and boundary condition treatment associated with the IDEAL algorithm on a collocated unstructured grid. Additionally, a comparative analysis between the semi-implicit method for pressure-linked equations (SIMPLE) and the IDEAL algorithm is conducted concerning computational efficiency under different grid types and flow conditions. The results indicate a significantly higher computational efficiency achieved by the IDEAL algorithm across all tested cases, attributed to its ability to overcome two fundamental assumptions inherent in the SIMPLE algorithm. The average acceleration ratio for these cases is approximately 3.13 (tSIMPLE/tIDEAL). This study serves as a valuable reference for the further development and application of the IDEAL algorithm in solving flow problems with complex irregular domains discretized by unstructured grids. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fermentation mechanism was studied by metabolomics and transcriptomics. • Arginine may be an important metabolite in hypersaline fermentation environments. • Bacillus amyloliquefaciens responds to salt stress via an active response system. • Bacillus amyloliquefaciens has potential in high salt fermented foods. Pixian broad bean paste is a renowned fermented seasoning. The fermentation of broad bean is the most important process of Pixian broad bean paste. To enhance the flavor of tank-fermented broad bean paste, salt-tolerant Bacillus amyloliquefaciens strain was inoculated, resulting in an increase in total amount of volatile compounds, potentially leading to different flavor characteristics. To investigate the fermentation mechanism, monoculture simulated fermentation systems were designed. Metabolomics and transcriptomics were used to explore Bacillus amyloliquefaciens ' transcriptional response to salt stress and potential aroma production mechanisms. The results highlighted different metabolite profiles under salt stress, and the crucial roles of energy metabolism, amino acid metabolism, reaction system, transportation system in Bacillus amyloliquefaciens ' hypersaline stress response. This study provides a scientific basis for the industrial application of Bacillus amyloliquefaciens and new insights into addressing the challenges of poor flavor quality in tank fermentation products. [ABSTRACT FROM AUTHOR]

The increasing penetration of intermittent renewable energy sources leads to a higher demand for flexible balancing service in the power system. Consequently, demand-side management techniques, such as utilizing flexible resources from residential electric-heating loads, provide a promising solution. However, due to various uncertainties such as stochastic weather and market prices, it is challenging to develop an economically efficient strategy. Hence, this paper proposes an economic operation optimization approach for residential electric-heating loads to develop optimal bidding and scheduling strategy in the multi-stage market. First, the dynamic characteristics of aggregated electric-heating loads are modeled as the virtual energy storage systems (VESS) to quantify the flexibility potential arising from the combination of building thermal inertia, user tolerance and thermal energy storage (TES). Subsequently, the joint energy and balancing service market is introduced to exploit the operating flexibility of VESS. A multi-agent deep reinforcement learning (MADRL) optimization framework is proposed to address the multi-objective problem at different decision frequency, which involves achieving lower economic costs while maintaining indoor comfort. Finally, we combine the DRL with imitation learning (IL) by introducing the behavior cloning mechanism to mitigate training process instability. It reduces the computational costs and eliminates the need for redundant additional structure. Comparative simulation experiments demonstrate the efficiency of data-driven optimization approach, which provides an adaptive, economic cost-effective and general solution for multi-type aggregators to activate their flexibility in dynamic markets. • The dynamic flexibility edge of electric-heating loads is quantified as VESS. • The MADRL is introduced to solve the optimization problem in multi-timescale market. • The IL is integrated to DRL to accelerate and smooth training process. • The proposed approach provides a general solution for multi-type LA strategy. [ABSTRACT FROM AUTHOR]

Chilling injury (CI) is a bottleneck factor constraining the refrigeration and cold chain logistics of mango fruit. Methyl jasmonate (MeJA) is an important phytohormone that can regulate multiple abiotic stresses. This study evaluated the potential effects of MeJA on CI in 'Guifei' mango fruit stored at 4 °C and its underlying mechanisms involved in the regulation of antioxidation and energy status. The application of 50 µM MeJA mitigated CI symptoms and improved ripening-related quality during refrigeration, as indicated by a lowered CI index, retarded declines in chlorophyll fluorescence (Fv/Fm) and chromaticity L * and advanced color transformation (from green to yellow), softening and accumulation of soluble solids. MeJA treatment repressed the increases in relative conductivity (RC), malondialdehyde (MDA) content and reactive oxygen species (ROS) (O 2 -. and H 2 O 2). Reduced ROS generation in MeJA-treated fruit was a consequence of the enhancement of antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). Ultrastructural observation revealed that MeJA treatment protected mitochondrial structure. MeJA treatment promoted intracellular energy synthesis and utilization, as indicated by increments in intracellular adenosine triphosphate (iATP) level, activities of isocitrate dehydrogenase (IDH), α-ketoglutarate dehydrogenase (α-KGDH), succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), H+-ATPase and Ca2+-ATPase as well as contents of reduced coenzymes (NADH and FADH 2). In addition, the expression levels of genes (MiAPYs , MiENTs , MiPUPs and MiAPRTs) related to extracellular ATP (eATP) hydrolysis, eATP transport and iATP regeneration were upregulated in response to MeJA, contributing to maintenance of eATP/iATP homeostasis. These findings suggest that MeJA could reinforce cold tolerance in mango fruit by inhibiting oxidative stress and promoting energy metabolism. • Methyl jasmonate (MeJA) relieved chilling injury in mango fruit during cold storage. • MeJA increased the activities of antioxidant enzymes in mango fruit. • MeJA protected mitochondrial structure and promoted energy synthesis in mango fruit. • MeJA enhanced activities of mitochondrial H+-ATPase and Ca2+-ATPase in mango fruit. • MeJA maintained eATP/iATP homeostasis by regulating iATP salvage pathways. [ABSTRACT FROM AUTHOR]

The effectiveness of the conventional friction pendulum isolator (FPI) is limited in complex geographical environments and unpredictable earthquake events due to its complex frictional properties and the requirement for a unified setup target. With a view to addressing the aforementioned issues, in conjunction with an adaptive variable friction pendulum isolator (AVFPI), a simple and practical mechanical model is proposed. After applying the mechanical model with a friction-dependent influence model, an improved response spectrum analysis procedure (IRS) is proposed for variable friction pendulum isolation systems. Notably, the proposed procedure allows for the consideration of the effects of variations in velocity, temperature, and pressure on the friction characteristics without the necessity for nonlinear response history analysis (NRHA). The procedure commences with obtaining a numerical model of friction dependency through friction material examinations, then proceeds to verifying the reliability of both the friction dependency and mechanical model through prototype tests of AVFPIs. The following study presents a proposed correction method that depends on random vibration theory to establish a functional relationship between the pseudo-velocity spectrum and the velocity spectrum. Additionally, an association is established between the peak velocity and the generation of frictional heat. Finally, the procedure is evaluated based on the results of an NRHA that takes friction dependence into account through a numerically variable friction pendulum isolation system. The results of the study indicate that the IRS provides a more accurate and secure assessment of the isolator displacement at various temperatures than the response spectrum method, which does not account for the influence of frictional dependency. The failure to consider the influence of friction dependency in high-temperature environments produces an underestimation of isolator slip displacement and a subsequent increase in failure rates. The Polytetrafluoroethylene (PTFE) friction materials that are currently in widespread use exhibit a strong correlation with friction dependence and, as a consequence, cause relatively large displacements at temperatures that are both low and high. The results of this study present an opportunity to expand how response spectrum analysis techniques can be applied to friction pendulum isolation systems. • A simplified mechanical hysteresis model for adaptive variable friction pendulum isolators is proposed. • A new friction material was tested and the velocity, pressure stress and temperature dependence expressions were obtained for the new friction material. • An expression for the friction coefficient of an adaptive variable friction pendulum isolator that takes into account the effects of velocity, pressure stress, and temperature dependence during nonlinear response history analysis is presented. • An improved method for analysing the response spectrum of variable friction pendulum isolation systems is proposed. Notably, the proposed procedure allows the consideration of the effects of velocity, temperature and pressure variations on the friction characteristics without the necessity to proceed to a nonlinear response history analysis (NRHA). • In the improved method of response spectrum analysis of variable friction pendulum isolation system, based on the correction method of stochastic vibration theory, the functional relationship between the pseudo velocity spectrum and the velocity spectrum is established, and a simplified calculation method for calculating frictional heat by peak velocity response is proposed. [ABSTRACT FROM AUTHOR]

Excessive fungicide residues in crops threaten food safety, and may initiate oxidative stress and cause phytotoxicity to products. Melatonin (Mel), a pleiotropic bioactive molecule, plays multiple physiological functions in plants. In this study, utilizing postharvest dipping with Mel and fungicide prochloraz (Pcz) as the model, we explored the effect of Mel on Pcz-triggered toxification and its underlying physiological mechanism in 'Guifei' mango fruit during storage at 25 °C. Results showed that pretreatment with 1 mmol L−1 Mel before exposure to 1.2 g L−1 Pcz (Mel + Pcz) reduced Pcz residues by 15.1% and 30.7% in mango fruit at 4 and 8 d, respectively, while ameliorating phytotoxicity to a greater extent than Pcz treatment alone. Microscopic observation revealed that Mel alleviated Pcz-triggered damage to lenticels on fruit exocarp tissue. Mel appreciably repressed Pcz-induced oxidative stress, as indicated by lower levels of reactive oxygen species, malondialdehyde, damaged DNA and carbonylated proteins and good maintenance of membrane integrity and mitochondrial membrane potential in Mel + Pcz fruit. Moreover, Pcz-induced increases in activities of antioxidant enzymes (superoxide dismutase, catalase and peroxidase), levels of ascorbate-glutathione cycle components and activities of pesticide degradative enzymes (cytochrome P450, glutathione S-transferase and glycosyltransferase) were further amplified after treatment with Mel + Pcz, which contributed to a stronger detoxification capacity in mango fruit. The study might provide a strategy for diminishing fungicide residues and attenuating phytotoxicity in postharvest fruits. • Melatonin (Mel) reduced prochloraz (Pcz) residues and alleviated toxicity in mangoes. • Mel attenuated Pcz-induced oxidative stress by activating antioxidant system in mangoes. • Mel promoted the increase in pesticide degradative enzyme activities in mangoes. • Mel could be a promising agent to detoxify fungicide in harvested mango fruit. [ABSTRACT FROM AUTHOR]