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991.
992.
Vladimir V. Aristov Anatoly S. Buchelnikov Yury D. Nechipurenko 《Entropy (Basel, Switzerland)》2022,24(2)
Some problems of describing biological systems with the use of entropy as a measure of the complexity of these systems are considered. Entropy is studied both for the organism as a whole and for its parts down to the molecular level. Correlation of actions of various parts of the whole organism, intercellular interactions and control, as well as cooperativity on the microlevel lead to a more complex structure and lower statistical entropy. For a multicellular organism, entropy is much lower than entropy for the same mass of a colony of unicellular organisms. Cooperativity always reduces the entropy of the system; a simple example of ligand binding to a macromolecule carrying two reaction centers shows how entropy is consistent with the ambiguity of the result in the Bernoulli test scheme. Particular attention is paid to the qualitative and quantitative relationship between the entropy of the system and the cooperativity of ligand binding to macromolecules. A kinetic model of metabolism. corresponding to Schrödinger’s concept of the maintenance biosystems by “negentropy feeding”, is proposed. This model allows calculating the nonequilibrium local entropy and comparing it with the local equilibrium entropy inherent in non-living matter. 相似文献
993.
Correlations of active galactic nuclei (AGNs) with microquasars are discussed based on the coexistence of the Blandford-Znajek (BZ) and magnetic coupling (MC) processes (CEBZMC) in black hole (BH) accretion disk.The proportions of several quantities of BH systems for both AGNs and microquasars are derived by combining the observational data with CEBZMC. It is shown that the square of the magnetic field at the BH horizon is inversely proportional to the BH mass, while the accretion rate of the disk is proportional to the BH mass. In addition, the very steep emissivity indexes from the recent XMM-Newton observations of the nearby bright Seyfert 1 galaxy MCG-6-30-15 and the microquasars XTE J1650-500 are well fitted by considering the MC effects on the disk radiation. These results suggest strongly the correlations of A GNs with microquasars. 相似文献
994.
995.
The fluorescence quenching of Rhodamine 6G (R6G) by graphene oxide (GO) was interrogated by R6G fluorescence measurements using a set of controlled GO samples with varied C/O ratios as the quencher.The carbonyl groups on the GO nanosheet turned to play a dominant role in quenching the R6G fluorescence.The quenching in the static regime can be described by the "sphere of action" model.The significant absorption of the R6G fluorescence by the ground-state complex formed between R6G and GO was identified to be responsible for the static quenching.This work offers helpful insights into the fluorescence quenching mechanisms in the R6G/GO system. 相似文献
996.
在 p H2 .0的氯乙酸 -氢氧化钠缓冲介质与吐温 - 80存在下 ,磺硝酚偶氮若丹宁 (NSPAR)与汞反应生成 2∶ 1稳定络合物 ,可被 Waters Sep- Pak C18小柱固相萃取 ,氮 -氮二甲基甲酰氨 (DMF)洗脱后光度法测定 ,λmax=5 5 0 nm,体系摩尔吸光系数ε=8.12× 10 4L· mol-1· cm-1。汞含量在 0 .0 5— 4 .0μg/m L内符合比耳定律 ,用于生物样品中汞含量的测定 ,结果令人满意 相似文献
997.
激光单分子探测技术的研究 总被引:6,自引:1,他引:6
文中介绍利用激光激发分子荧光的方法探测液体中单个染料分子的新技术,以及作者自行设计和研制的激光单分子探测谱仪。通过探测“光子爆发”,把单个染料分子的荧光同很强的背景杂散光区别开来。进一步用82MHz高重复频率的锁模激光器和时间门符合技术,成功地消除了Raman散射光。目前该谱仪达到的检测限为灵敏区内仅有~7个R6G分子。 相似文献
998.
999.
Synthesis and characterization of Sr3Al2O6:Eu2+, Dy3+ phosphors prepared by sol-gel-combustion processing
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A type of red luminescent Sr3Al2O6:Eu2+, Dy3+ phosphor powder is synthesised by sol-gel-combustion processing, with metal nitrates used as the source of metal ions and citric acid as a chelating agent of metal ions. By tracing the formation process of the sol-gel, it is found that it is necessary to reduce the amount of NO3- by dropping ethanol into the solution for forming a stable and homogeneous sol-gel. Thermogravimetric and Differential Scanning Calorimeter Analysis, x-ray diffractionmeter, scanning electron microscopy and photoluminescence spectroscopy are used to investigate the luminescent properties of the as-synthesised Sr3Al2O6:Eu2+, Dy3+. The results reveal that the Sr3Al2O6 crystallises completely when the combustion ash is sintered at 1250 C. The excitation and the emission spectra indicate that the excitation broadband lies mainly in a visible range and the phosphors emit a strong light at 618 nm under the excitation of 472 nm. The afterglow of (Sr0.94Eu0.03Dy0.03)3Al2O6 phosphors sintered at 1250 ℃ lasts for over 1000 s when the excited source is cut off. 相似文献
1000.
Wen-Rong Liu 《中国物理 B》2022,31(3):37305-037305
The two-dimensional (2D) materials with nodal line band crossing have been attracting great research interest. However, it remains a challenge to find high-stable nodal line structure in 2D systems. Herein, based on the first-principles calculations and theoretical analysis, we propose that monolayer B6O possesses symmetry protected Dirac nodal line (DNL) state, with its Fermi velocity of 106 m/s in the same order of magnitude as that of graphene. The origin of DNL fermions is induced by coexistence of time-reversal symmetry and inversion symmetry. A two-band tight-binding model is further given to understand the mechanism of DNL. Considering its robustness against spin—orbit coupling (SOC) and high structural stability, these results suggest monolayer B6O as a new platform for realizing future high-speed low-dissipation devices. 相似文献