Kinetics

动力学
  • 文章类型: Journal Article
    在固体推进剂中,燃烧催化剂起着至关重要的作用。这里,我们介绍了一种在水存在下UIO-66(Mn)自组装的方便方法,导致制备Mn/C气凝胶。气凝胶已成功用于高氯酸铵(AP)的热催化分解。结果表明,掺入2%质量分数的Mn/C气凝胶可将AP分解的峰值温度提高约87.5°C。Mn/C气凝胶显示出优异的催化性能。结合动力学,我们提出了一种热催化机理。
    In solid propellants, combustion catalysts play a crucial role. Here, we introduce a convenient method for the self-assembly of UIO-66 (Mn) in the presence of water, leading to the preparation of Mn/C aerogels. The aerogels were successfully utilized in the thermocatalytic decomposition of ammonium perchlorate (AP). The results indicate that the incorporation of 2% mass fraction of Mn/C aerogels enhances the peak temperature of AP decomposition by approximately 87.5°C. Mn/C aerogels demonstrate excellent catalytic performance. In combination with kinetics, we propose a thermal catalytic mechanism.
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  • 文章类型: Journal Article
    非热(脉冲电场,PEF)和热预处理(真空蒸汽脉冲烫漂,VSPB)对干燥动力学,质量属性,研究了百合鳞片的多维微观结构。结果表明,与未处理的百合鳞片相比,PEF和VSPB预处理均提高了干燥速率。具体来说,PEF预处理使干燥时间缩短29.58%-43.60%,而VSPB实现了46.91%的干燥时间减少。与VSPB处理的样品相比,PEF处理促进了酚和类黄酮的增强浸出,从而增加抗氧化活性。用PEF和VSPB处理提高了干百合的复水率,这与微观结构密切相关。Weibull分布和Page模型证明了百合鳞片的干燥和复水动力学的极好拟合,分别(R2>0.993)。对多维微观结构和超微结构的分析证实了不同处理之间水分迁移和植物化学物质含量的变化。因此,这项研究为水果和蔬菜非热预处理的潜力提供了技术支持。
    The effects of the non-thermal (pulsed electric field, PEF) and thermal pretreatment (vacuum steam pulsed blanching, VSPB) on the drying kinetics, quality attributes, and multi-dimensional microstructure of lily scales were investigated. The results indicate that both PEF and VSPB pretreatments improved the drying rate compared to untreated lily scales. Specifically, PEF pretreatment reduced the drying time by 29.58 % - 43.60 %, while VSPB achieved a 46.91 % reduction in drying time. PEF treatment facilitated the enhanced leaching of phenols and flavonoids compared to VSPB treated samples, thereby increasing antioxidant activity. The rehydration ratio of the dried lilies was improved with PEF and VSPB treatment, which closely related to the microstructure. Weibull distribution and Page model demonstrated excellent fit for the drying and rehydration kinetics of lily scales, respectively (R2 > 0.993). The analysis of multi-dimensional microstructure and ultrastructure confirmed the variations in moisture migration and phytochemical contents among different treatments. Consequently, this study offers insights into the technological support for the potential of non-thermal pretreatment in fruits and vegetables.
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  • 文章类型: Journal Article
    镁离子(Mg2+)在利用具有二磷酸基团的底物的II类萜烯环化酶中是至关重要的。有趣的是,这些酶催化不裂解二磷酸基团的反应,而是通过质子化引发反应。在我们最近的研究中,我们在showdoensis链霉菌中发现了一种新型的II类倍半萜环化酶。值得注意的是,我们确定了其晶体结构,并在其活性位点内鉴定了Mg2。这一发现揭示了先前难以捉摸的II类萜烯环化酶中Mg2结合的问题。在这一章中,我们概述了我们发现这种新型酶的方法,包括其纯化步骤,结晶,和动力学分析。
    Magnesium ions (Mg2+) are crucial in class II terpene cyclases that utilize substrates with diphosphate groups. Interestingly, these enzymes catalyze reactions without cleaving the diphosphate group, instead initiating the reaction through protonation. In our recent research, we discovered a novel class II sesquiterpene cyclase in Streptomyces showdoensis. Notably, we determined its crystal structure and identified Mg2+ within its active site. This finding has shed light on the previously elusive question of Mg2+ binding in class II terpene cyclases. In this chapter, we outline our methods for discovering this novel enzyme, including steps for its purification, crystallization, and kinetic analysis.
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  • 文章类型: Journal Article
    超分辨率成像,尤其是单分子定位方法,引发了一场荧光团工程革命,追逐稀疏的单分子暗亮闪烁变换。然而,从结构上设计荧光团操纵单分子闪烁动力学是一个挑战。在这种追求中,我们通过将可光活化的亚硝基笼式策略创新地整合到自闪烁的磺酰胺中以形成亚硝基笼式磺酰胺罗丹明(NOSR)来开发触发策略。我们的荧光团在光触发的笼式单元释放后表现出可控的自闪烁事件。与自闪烁类似物相比,这种出色的闪烁动力学改善了微管的超分辨率成像完整性。借助最重要的单分子荧光动力学,我们成功地重建了核孔的环状结构和线粒体外膜的轴向形态。我们预见,我们的光活化和自闪烁的合成方法将有助于罗丹明设计超分辨率成像。
    Super-resolution imaging, especially a single-molecule localization approach, has raised a fluorophore engineering revolution chasing sparse single-molecule dark-bright blinking transforms. Yet, it is a challenge to structurally devise fluorophores manipulating the single-molecule blinking kinetics. In this pursuit, we have developed a triggering strategy by innovatively integrating the photoactivatable nitroso-caging strategy into self-blinking sulfonamide to form a nitroso-caged sulfonamide rhodamine (NOSR). Our fluorophore demonstrated controllable self-blinking events upon phototriggered caging unit release. This exceptional blink kinetics improved the super-resolution imaging integrity on microtubules compared to self-blinking analogues. With the aid of paramount single-molecule fluorescence kinetics, we successfully reconstructed the ring structure of nuclear pores and the axial morphology of mitochondrial outer membranes. We foresee that our synthetic approach of photoactivation and self-blinking would facilitate rhodamine devising for super-resolution imaging.
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  • 文章类型: Journal Article
    众所周知,呼吸道含有包括细菌在内的微生物群落,病毒,和真菌。新技术对鉴定未知或与培养无关的物种做出了巨大贡献,并揭示了群落与宿主免疫系统的相互作用。现有的呼吸道微生物组和来自供体肺移植物的移植微生物组的基本平衡提供了肺移植(LT)受体中微环境动态变化的极端爆发。移植物中的菌群失调不仅与修饰的微生物成分有关,而且还涉及宿主移植物的动力学。“这标志着移植物移植损伤的目的地,急性排斥反应,感染,和长期生存的慢性同种异体移植功能障碍发展。当使用基因修饰的猪来源的器官时,微生物组来源的因子可能有助于肺异种移植物的存活。这里,我们回顾了各种移植前适应症的移植肺中微生物群落的动力学和弹性的最先进的知识。概念和分析观点已经沿着时间序列进行了说明,深入了解微生物组和肺移植物。未来在精密工具上的努力,复杂的模型,需要新的靶向治疗方案来改善这些患者的长期生存率.
    The respiratory tract is known to harbor a microbial community including bacteria, viruses, and fungi. New techniques contribute enormously to the identification of unknown or culture-independent species and reveal the interaction of the community with the host immune system. The existing respiratory microbiome and substantial equilibrium of the transplanted microbiome from donor lung grafts provide an extreme bloom of dynamic changes in the microenvironment in lung transplantation (LT) recipients. Dysbiosis in grafts are not only related to the modified microbial components but also involve the kinetics of the host-graft \"talk,\" which signifies the destination of graft allograft injury, acute rejection, infection, and chronic allograft dysfunction development in short- and long-term survival. Microbiome-derived factors may contribute to lung xenograft survival when using genetically multimodified pig-derived organs. Here, we review the most advanced knowledge of the dynamics and resilience of microbial communities in transplanted lungs with various pretransplant indications. Conceptual and analytical points of view have been illustrated along the time series, gaining insight into the microbiome and lung grafts. Future endeavors on precise tools, sophisticated models, and novel targeted regimens are needed to improve the long-term survival in these patients.
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  • 文章类型: Journal Article
    由于硬碳阳极具有成本效益和出色的平台容量,因此在钠离子电池中具有出色的潜力。然而,高原容量与电池操作的截止电压的接近以及由高速率极化引起的过早截止电压响应极大地限制了高原容量的开发,引起了人们对高高原容量硬碳的低率性能的极大关注。在这项工作中,提出了一种简单的预氧化策略来制造木质素衍生的硬碳。由于引入了膨胀的假石墨域和高速闭孔,高平台容量和碱化动力学均显着增强。令人印象深刻的是,优化的硬碳表现出增加的可逆容量从252.1到302.0mAhg-1,以及优异的倍率性能(174.7mAhg-1在5C)和稳定的循环能力超过500次循环。这项研究为调节生物质衍生的硬碳材料的微观结构以促进平台钠储存动力学铺平了一条低成本且有效的途径。
    Hard carbon anode demonstrates exceptional potential in sodium-ion batteries due to their cost-effectivenss and superior plateau capacity. However, the proximity of the plateau capacity to the cut-off voltage of battery operation and the premature cut-off voltage response caused by polarization at high rates greatly limit the exploitation of plateau capacities, raising big concerns about inferior rate performance of high-plateau-capacity hard carbon. In this work, a facile pre-oxidation strategy is proposed for fabricating lignin-derived hard carbon. Both high-plateau capacity and sodiation kinetics are significantly enhanced due to the introduction of expanded pseudo-graphitic domains and high-speed closed pores. Impressively, the optimized hard carbon exhibits an increased reversible capacity from 252.1 to 302.0 mAh g-1, alongside superior rate performance (174.7 mAh g-1 at 5 C) and stable cyclability over 500 cycles. This study paves a low-cost and effective pathway to modulate the microstructure of biomass-derived hard carbon materials for facilitating plateau sodium storage kinetics.
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  • 文章类型: Journal Article
    背景:在城市跑步或马拉松比赛中,经常遇到平地和上下斜坡的变化,导致下肢生物力学的变化。跑鞋的纵向弯曲刚度影响跑步性能。
    目的:本研究旨在研究在跑鞋的不同纵向弯曲刚度(LBS)水平下,从水平地面过渡到上坡时下肢的生物力学变化。
    方法:招募了15名男性业余跑步者,并穿着三种不同的LBS跑鞋进行了测试。要求参与者用右脚以3.3m/s±0.2的速度通过力平台。运动学数据和GRF是同步收集的。每个参与者完成并记录每双鞋10次成功的实验。
    结果:膝关节矢状面的运动范围随着纵向弯曲刚度的增加而减小。踝关节矢状面的积极功增加,而敏锐关节的积极功减少。膝关节的负功在矢状面增加。矢状平面中meta趾关节的正功增加。
    结论:从水平面上运行过渡到上坡运行,穿着高LBS的跑鞋,可以提高下肢功能的效率。然而,跑鞋较高的LBS增加了膝关节的能量吸收,可能会增加膝盖受伤的风险。因此,业余爱好者应该选择跑步时刚度最佳的跑鞋。
    BACKGROUND: During city running or marathon races, shifts in level ground and up-and-down slopes are regularly encountered, resulting in changes in lower limb biomechanics. The longitudinal bending stiffness of the running shoe affects the running performance.
    OBJECTIVE: This research aimed to investigate the biomechanical changes in the lower limbs when transitioning from level ground to an uphill slope under different longitudinal bending stiffness (LBS) levels in running shoes.
    METHODS: Fifteen male amateur runners were recruited and tested while wearing three different LBS running shoes. The participants were asked to pass the force platform with their right foot at a speed of 3.3 m/s ± 0.2. Kinematics data and GRFs were collected synchronously. Each participant completed and recorded ten successful experiments per pair of shoes.
    RESULTS: The range of motion in the sagittal of the knee joint was reduced with the increase in the longitudinal bending stiffness. Positive work was increased in the sagittal plane of the ankle joint and reduced in the keen joint. The negative work of the knee joint increased in the sagittal plane. The positive work of the metatarsophalangeal joint in the sagittal plane increased.
    CONCLUSIONS: Transitioning from running on a level surface to running uphill, while wearing running shoes with high LBS, could lead to improved efficiency in lower limb function. However, the higher LBS of running shoes increases the energy absorption of the knee joint, potentially increasing the risk of knee injuries. Thus, amateurs should choose running shoes with optimal stiffness when running.
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  • 文章类型: Journal Article
    在这项研究中,RM(红泥)用硫酸酸化,并将酸化的ARM(酸化的赤泥)用作处理含抗生素废水的创新吸附材料。吸附条件,动力学,等温线,热力学,并对环丙沙星对CIP(环丙沙星)的作用机制进行了研究。ARM的表征涉及扫描电子显微镜(SEM)等技术,透射电子显微镜(TEM),Brunauer-Emmett-Teller(BET),X射线衍射(XRD)X射线荧光(XRF),热重分析(TGA),和NH3-TPD分析。吸附研究采用响应面方法(RSM)进行实验设计。结果表明,ARM可以有效吸收CIP。RSM优化实验表明,影响吸附量最显著的模型项是溶液pH,CIP初始浓度,和ARM剂量,在此条件下,预测的最大吸附容量达到7.30mg/g。吸附动力学符合伪二阶模型,虽然平衡数据符合朗缪尔-弗洛伊德利希等温线,产量最大容量值为7.35毫克/克。吸附过程自发发生并吸收热量,由-83.05和-91.50kJ/mol之间的ΔGθ值证明,ΔSθ为281.6J/mol/K,和ΔHθ为0.86kJ/mol。使用衰减全反射傅里叶变换红外光谱(ATR-FTIR)的分析表明,ARM中的Al-O与酯基-COOinCIP之间存在复杂的反应。CIP中的C=O键可能会发生轻微的静电相互作用或与ARM的内部球形表面结合。研究结果表明,ARM是一种有前途的高效吸附剂,可用于去除废水中的CIP。
    In this study, RM (red mud) was acidified with sulfuric acid, and the acidified ARM (acidified red mud) was utilized as an innovative adsorption material for treating antibiotic-containing wastewater. The adsorption conditions, kinetics, isotherms, thermodynamics, and mechanism of ARM for CIP (ciprofloxacin) were investigated. The characterization of the ARM involved techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TGA), and NH3-TPD analysis. Adsorption studies employed a response surface methodology (RSM) for the experimental design. The results showed that ARM can absorb CIP effectively. The RSM optimal experiment indicated that the most significant model terms influencing adsorption capacity were solution pH, CIP initial concentration, and ARM dosage, under which the predicted maximum adsorption capacity achieved 7.30 mg/g. The adsorption kinetics adhered to a pseudo-second-order model, while equilibrium data fitted the Langmuir-Freundlich isotherm, yielding maximum capacity values of 7.35 mg/g. The adsorption process occurred spontaneously and absorbed heat, evidenced by ΔGθ values between -83.05 and -91.50 kJ/mol, ΔSθ at 281.6 J/mol/K, and ΔHθ at 0.86 kJ/mol. Analysis using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) indicated a complex reaction between the Al-O in the ARM and the ester group -COO in CIP. The C=O bond in CIP was likely to undergo a slight electrostatic interaction or be bound to the internal spherical surface of the ARM. The findings indicate that ARM is a promising and efficient adsorbent for CIP removal from wastewater.
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  • 文章类型: Journal Article
    在这项研究中,我们报道了一种新型高灵敏度基于强度的表面等离子体共振成像(SPRi)生物传感器的成功开发及其在检测分子相互作用中的应用。通过优化激发波长并采用波分复用(WDM)算法,该系统可以根据样品的初始折射率确定最佳激发波长,而无需调整入射角。实验结果表明,该系统的折射率分辨率达到1.77×10-6RIU。此外,它可以获得初始折射率在1.333至1.370RIU范围内的样品的最佳激发波长,并精确监测0.0037RIU范围内的变化,而无需调整入射角。此外,我们的新SPRi技术实现了高通量生物分子结合过程的实时检测,能够分析动力学参数。这项研究有望促进更精确的SPRi分子相互作用分析技术的发展。
    In this study, we report the successful development of a novel high-sensitivity intensity-based Surface Plasmon Resonance imaging (SPRi) biosensor and its application for detecting molecular interactions. By optimizing the excitation wavelength and employing a wavelength division multiplexing (WDM) algorithm, the system can determine the optimal excitation wavelength based on the initial refractive index of the sample without adjusting the incidence angle. The experimental results demonstrate that the refractive index resolution of the system reaches 1.77×10-6 RIU. Moreover, it can obtain the optimal excitation wavelength for samples with an initial refractive index in the range of 1.333 to 1.370 RIU and accurately monitor variations within the range of 0.0037 RIU without adjusting the incidence angle. Additionally, our new SPRi technique realized real-time detection of high-throughput biomolecular binding processes, enabling analysis of kinetic parameters. This research is expected to advance the development of more accurate SPRi technologies for molecular interaction analysis.
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  • 文章类型: Journal Article
    尽管进行了广泛的研究,碱-二氧化硅反应(ASR)的进展与ASR引起的混凝土膨胀之间的关系,特别是对于反应性慢的异质聚集体,没有被彻底理解。在本文中,当暴露于NaOH溶液时,砂岩中存在的反应性二氧化硅的溶解动力学,随着岩石棱柱在ASR条件下的膨胀特性,被研究过。实验结果表明,ASR表现为一级反应,伴随着OH-浓度随时间的指数下降,二氧化硅的溶解速率主要受扩散动力学控制。值得注意的是,升高温度会加速ASR,这增加了有限空间中的膨胀压力,导致更显著的总量扩张。相反,较高的温度也导致ASR凝胶在聚集体中的保留减少,导致ASR扩展的缓解。我们的发现强调,较大的聚集体保留了更大量的凝胶,导致更明显的扩张。基于混凝土ASR膨胀与高低温的关系,建立ASR预测模型,在实验中,应仔细考虑固化温度范围和骨料分级尺寸等参数。
    Despite extensive research, the relationship between the progression of the alkali-silica reaction (ASR) and the expansion of concrete due to ASR, particularly for the heterogeneous aggregate with slow reactivity, is not thoroughly understood. In this paper, the dissolution kinetics of reactive silica present in sandstone when exposed to NaOH solutions, alongside the expansion characteristics of rock prisms under ASR conditions, were studied. The experimental results indicate that ASR behaves as a first-order reaction, accompanied by an exponential decrease in the concentration of OH- over time, and the dissolution rate of silica is predominantly governed by diffusion dynamics. Notably, increasing the temperature accelerates ASR, which augments the expansive pressure in a confined and limited space, leading to more significant aggregate expansion. Conversely, higher temperatures also result in a diminished retention of ASR gels within the aggregate, leading to the mitigation of ASR expansion. Our findings underscore that larger aggregates retain a greater quantity of gels, resulting in more pronounced expansion. To establish an ASR prediction model based on the relationship of the ASR expansion of concrete to high and low temperatures, the parameters such as the range of curing temperatures and the grading size of aggregates should be carefully considered for the experiments.
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