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31.
Mengya Kong Yuyang Gu Yingjie Chai Jiaming Ke Yulai Liu Xincheng Xu Zhanxian Li Wei Feng Fuyou Li 《中国科学:化学(英文版)》2021,(6):974-984
Luminescence nanothermometry makes non-invasive and real-time temperature readings possible in living animals. However,the spectral fluctuation in tissues and fluids, as well as the interaction between fluorophores and environment hinders accuracy of the thermometry. Here, we report a luminescence lifetime-based nanothermometry which specifically addresses this problem. A temporal based calibration(lifetime sensing) in the NIR range, an endogenous thermal response as well as a polymer encapsulation evading environmental factors, altogether help to pinpoint temperature in vivo. Thanks to the highly condensed NdYb ions in a well-protected tiny core-shell nanocrystal(overall 11 nm), a temperature sensitivity about 2.07% K~(-1)(with 5% Yb~(3+) doped nanoparticles) and an accuracy of 0.27 K(with 25% Yb~(3+) doped nanoparticles) in biological fluids are achieved.Hopefully, combining thermally activated energy transfer nanothermometer with anti-interference lifetime thermometry would provide a more accurate temperature measurement for biological and preclinical studies. 相似文献
32.
The main purpose of this paper is to study the persistence of the general multispecies competition predator-pray system with Holling Ⅲ type functional response.In this system,the competition among predator species and among prey species are simultaneously considered.By using the comparison theory and qualitative analysis,the sufficient conditions for uniform strong persistence are obtained. 相似文献
33.
In this paper we report some explicit evolutionary PDEs of the Drinfeld-Sokolov hierarchy of type E(1)6,and show how the unknown functions in these PDEs are rel... 相似文献
34.
35.
在溴代十六烷基吡啶存在下5-Br-PADAP分光光度法测定水中微量铁的研究 总被引:1,自引:0,他引:1
研究了显色剂2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(简称为5-Br-PADAP)与铁(Ⅱ)显色反应条件,在pH=6.0的醋酸-醋酸钠缓冲体系中,采用阳离子表面活性剂溴代十六烷基吡啶增溶增敏。铁(Ⅱ)与显色剂形成的配合物组成为Fe(Ⅱ)∶R=1∶2,络合物具有两个吸收峰,分别位于λ1=556nm与λ2=748nm。选择748nm进行测定,其摩尔吸光系数为ε748=3.3×104L·mol-1·cm-1。铁含量在0—30μg/25mL范围内服从比耳定律。此法用于水样中微量铁的测定,结果准确可靠。 相似文献
36.
37.
Lingmin Dai Ke Zhong Yan Ma Xiaoqian Cui Yuhang Sun Ang Zhang Guomin Han 《Molecules (Basel, Switzerland)》2022,27(9)
Acetaldehyde is a critical reactant on modifying the phenolic profile during red wine aging, suggesting that the acetaldehyde-mediated condensation can be responsible for the variation of antioxidant activity during the aging of this beverage. The present study employs exogenous acetaldehyde at six levels of treatment (7.86 ± 0.10–259.02 ± 4.95 mg/L) before the bottle aging of Merlot wines to encourage phenolic modification. Acetaldehyde and antioxidant activity of wine were evaluated at 0, 15, 30, 45, 60 and 75 days of storage, while monomeric and polymeric phenolics were analyzed at 0, 30 and 75 days of storage. The loss of acetaldehyde was fitted to a first-order reaction model, the rate constant (k) demonstrated that different chemical reaction happened in wines containing a different initial acetaldehyde. The disappearance of monomeric phenolics and the formation of polymeric phenolics induced by acetaldehyde could be divided into two phases, the antioxidant activity of wine did not alter significantly in the first phase, although most monomeric phenolics vanished, but the second phase would dramatically reduce the antioxidant activity of wine. Furthermore, a higher level of acetaldehyde could shorten the reaction time of the first phase. These results indicate that careful vinification handling aiming at controlling the acetaldehyde allows one to maintain prolonged biological activity during wine aging. 相似文献
38.
利用Rosemount气体分析仪和定碳炉搭建起固定床燃烧反应试验平台,通过红外光谱分析技术定量分析沥青及其胶浆在高升温速率条件下燃烧反应的有毒气态产物成分、及其释放规律。研究表明,在高升温速率、近等温条件下,沥青及胶浆的燃烧过程可近似分为活泼挥发组分析出燃烧、二次挥发析出结合残炭燃烧两个阶段,其主要气态产物为CO2,CO,NO,NO2及SO2。沥青材料中活泼挥发组分含量是影响燃烧气态产物释放规律的关键因素之一,减少沥青材料中活泼挥发组分的含量可有效降低燃烧气态产物的生成、尤其是CO的产生。 相似文献
39.
3 GPa熔融盐固体介质三轴高温压力容器的轴压摩擦力标定 总被引:1,自引:0,他引:1
在温度标定和围压标定的基础上,采用轴压循环方法,对3 GPa固体介质三轴高温高压实验系统的轴压摩擦力进行了标定,分析了围压、温度、轴向位移速率、装样方式(盐套类型)等实验条件对轴压摩擦力的影响。结果表明:静摩擦力、挤压摩擦力和滑动摩擦力3种轴压摩擦力对轴向应力的影响不同,其中静摩擦力和挤压摩擦力对轴向应力的影响很小,影响应力精度的主要是滑动摩擦力。静摩擦力及滑动摩擦力与围压正相关;静摩擦力与轴向位移速率正相关,但受其影响较小,滑动摩擦力不受其影响;静摩擦力和滑动摩擦力与温度负相关,并且受其影响较显著;盐套类型对轴压摩擦力的影响较大,当实验条件接近盐套熔点时,轴压摩擦力显著降低,当样品周围的盐套处于熔融状态时,轴压摩擦力最小。基于此,确定了标定轴压摩擦力的具体步骤,并对角闪岩的应力-应变曲线进行了轴压摩擦力标定。对比轴压摩擦力校正前、后的应力-应变曲线发现,经过轴压摩擦力校正的应力-应变曲线能更好地反映样品的实际变形情况。 相似文献
40.
Ji-Wu Huang Chuang-Jun Li Jing-Zhi Yang Chuan Li Yu Zhang Ke Liu Yue Yu Jian-Dong Jiang Dong-Ming Zhang 《中国化学》2021,(5):1129-1137
Main observation and conclusion
Eight new polycyclic phloroglucinol meroterpenoids guajamers A-H (1-8),a methylated benzoylphloroglucinol meroterpenoid guajamer... 相似文献