Reclaiming of ground rubber tire (GRT) by a novel reclaiming agent

The present paper describes the mechanical reclaiming of ground rubber tire (GRT) by tetra methyl thiuram disulfide (TMTD), a multi-functional reclaiming agent. The versatility of the proposed agent is that it acts as a reclaiming agent during reclaiming and as a curing agent during revulcanization of the reclaimed sample. Reclaiming of GRT was carried out on an open two roll mixing mill at various time intervals and different concentrations of the reclaiming agent (TMTD). The degree of reclaiming was evaluated by measurement of the gel content, inherent viscosity of sol rubber, Mooney viscosity of the reclaimed rubber, crosslink density, swelling ratio and molecular weight between two crosslink bonds as a function of milling time. Also, the influence of the gel content on crosslink density at various time intervals on the open two roll mixing mill was determined. A unique correlation between gel fraction and crosslink density obtained at various time intervals and concentrations of reclaiming agent indicated that an optimization of the concentration of TMTD and milling time has a positive influence on improving the efficiency of reclaiming. The reclaiming conditions have been optimized in view of the mechanical properties of the revulcanized GRT and the aging resistance properties of the revulcanized reclaim. The influence of the concentration of sulfur on the mechanical properties in the revulcanized reclaim was also studied. Scanning electron microscopy (SEM) studies further indicate the coherency and homogeneity in the revulcanized reclaim rubber when reclamation is carried out by optimum concentration of TMTD after maximum time of reclaiming.     

Herding and idiosyncratic choices: Nonlinearity and aging-induced transitions in the noisy voter model

We consider the herding-to-non-herding transition caused by idiosyncratic choices or imperfect imitation in the context of the Kirman Model for financial markets, or equivalently the Noisy Voter Model for opinion formation. In these original models, this is a finite-size transition that disappears for a large number of agents. We show how the introduction of two different mechanisms makes this transition robust and well defined. A first mechanism is nonlinear interactions among agents taking into account the nonlinear effect of local majorities. The second one is aging, so that the longer an agent has been in a given state the more reluctant she becomes to change state.     

Study on flavonoid and bioactivity features of the pericarp of Citri Reticulatae ‘chachi' during storage

The mature pericarp of Citri Reticulatae 'Chachi' (PCRC) is one of the six traditional Chinese medicinal materials that should be used after long storage, and it was regarded that the longer the medicine was stored, the better. However, the aging mechanism of the medicine is not clear. To further investigate the effect of aging on the main active flavonoids of PCRC, ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-MS/MS) and metabolomics analysis were used to analyze the flavonoids of PCRC stored for different periods. In the results, 219 flavonoids were detected. 5,7,3′,4′,5′-pentamethoxy dihydroflavone and 2′-hydroxy-3,4,5,3′4′,6′-hexamethoxychalcone were found from PCRC for the first time. According to the clustering analysis of metabolites, aging times of 0 year, 1 year, and 2 year were clustered into one group, and aging times of 3 year, 4 year, and 29 year were clustered into the other group. Quantitative analysis showed that the former group contained a greater amount of 4 flavonoids than the latter group, while the latter group contained a greater amount of 15 polymethoxyflavonoids. The newly harvested PCRC was compared with the other 5 groups of PCRC (stored for 1, 2, 3, 4, and 29 years). Eight flavonoids, tectochrysin, apigenin, 2′-hydroxyisoflavone, luteolin, 6-hydroxyluteolin, gallocatechin, quercetin -O- acetylhexoside and apigenin ?7-O-[β-D-glucuronide (1 → 2) -O-β-D-glucuronide], were used as marker components to discriminate newly harvested PCRC and aging PCRC. In addition, the antioxidant potency composite index (APC) indicated that the PCRC stored for three or four years had stronger antioxidant activity than the PCRC stored for other periods. By means of molecular docking, it was reviewed that the amount of antiviral components against SARS-CoV-2 in freshly harvested PCRC was significantly higher than that in aging PCRC. The results in this study supplied scientific data for quality control, evaluation, and rational utilization of PCRC and basic information for further analysis of the metabolic regulation of the active components of the PCRC.     

具有混音功能的新型语音卡设计与实现

为满足某控制系统实时记录语音和播放录音的实际需求,基于语音压缩编码技术,以现场可编程门阵列(FPGA)为控制核心,设计实现了16个通道采集语音信号,进行ADPCM编码,将语音文件以WAVE格式存储,集监听、播放指定语音通道及任意时间段录音于一体的紧凑型PCI(CPCI)板卡。该板卡区别于传统语音卡的创新点在于运用语音叠加技术使板卡具有混音功能,能够将不同通道语音混音、记录存储,同时具有压缩比可自由选择的功能。详细介绍了板卡的组成机构、工作原理、硬件设计和软件设计。最后进行实验测试,板卡语音存储、语音回放等各项功能正常,音质良好,验证了设计方案的可行性与实用性。     

Microstructure and age characterization of Cu-15Ni-8Sn alloy coatings by laser cladding

The present work has investigated the influence of direct aging treatment on the precipitation sequence and properties of the Cu-15Ni-8Sn alloy coatings prepared by laser cladding. The experimental results show that the tendency of Sn segregation in the conventional Cu-15Ni-8Sn solidification microstructure is effectively relieved. Before aging, there are only two phases in the coating: the α-Cu solid solution dendrites with 7 wt.% Sn solubility, and a small fraction of Sn-enriched δ-phase at the interdendrites in rapid solidified microstructure. After the coating was directly aged at 370 °C without traditional solution pretreatment, the α-Cu solid solution dendrites experience precipitations in the order of pure spinodal decomposition, DO₂₂-ordered structure and discontinue γ-DO₃. The microhardness of the coating treated by direct aging reached 390 HV 0.5, which was higher than that treated by conventional solution and aging process owing to the solidified fine grains and hardening effect of spinodal decomposition. In addition, the Sn-enriched δ-phase at the interdendrites also decomposes to laminar discontinuous precipitated γ-DO₃ phase after aging. Precipitation sequence and properties of the clad coatings change obviously during the direct aging treatment.     

Accelerated aging and aging mechanism of acrylic sealant

One-component acrylic latex sealants with different moduli were subjected to accelerated aging tests, heat aging at different temperatures, xenon arc and UV exposure. The effects of various aging factors on sealant properties were studied by reviewing the appearance and mechanical properties. The aging mechanism was evaluated by thermal analysis, FTIR and solvent swell. The results show that a good relation exists among mechanical properties after aging; mild accelerated aging conditions and short aging times are enough to lead to obvious degradation of acrylic sealants with low modulus. Fillers with ingredients within high modulus may resist UV radiation effectively and enhance their durability but the quantity must be proper. The degree of chain breaking caused by UV is larger than that by heat aging. The study also shows that there are the same or similar aging mechanisms for different aging conditions and that the cure reaction by water volatilisation dominates the initial period of aging while degradation will be induced when aging time is longer and it can result in changes of molecular structure.