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关键词： Free energy   Equilibrium constant   Absorption   Solvation   Enthalpy  

摘要： Temperature-dependent correlations for equilibrium constants (ln K) and heat of absorption (Delta H-abs) of different reactions (i.e., deprotonation, double deprotonation, carbamate formation, protonated carbamate formation, dicarbamate formation) involved in the piperazine (PZ)/CO2/H2O system have been calculated using computational chemistry based ln K values input to the Gibbs-Helmholtz equation. This work also presents an extensive study of gaseous phase free energy and enthalpy for different reactions using composite (G3MP2B3, G3MP2, CBS-QB3, and G4MP2) and density functional theory [B3LYP/6-311++G(d,p)] methods. The explicit solvation shell (ESS) model and SM8T solvation free energy coupled with gaseous phase density functional theory calculations give temperature-dependent reaction equilibrium constants for different reactions. Calculated individual and overall reaction equilibrium constants and enthalpies of different reactions involved in CO2 absorption in piperazine solution are compared against experimental data, where available, in the temperature range 273.15-373 K. Postcombustion CO2 capture (PCC) is a temperature swing absorption-desorption process. The enthalpy of the solution directly correlates with the steam requirement of the amine regeneration step. Temperature-dependent correlations for ln K and Delta H-abs calculated using computational chemistry tools can help evaluate potential PCC solvents' thermodynamics and cost-efficiency. These correlations can also be employed in thermodynamic models (e.g., e-UNIQUAC, e-NRTL) to better understand postcombustion CO2 capture solvent chemistry.

关键词： generalised differential modulation   Golden code   multiple-input symbols   quadrature amplitude modulation   sphere detection   STBC  

摘要： The receiver of a conventional differential modulation scheme performs detection without knowledge of the channel state information (CSI). This results in a 3 dB performance loss compared to coherent modulation. In order to enhance this error performance, generalised differential modulation is utilised. This paper extends the generalised differential modulation scheme to multiple-input symbol Golden code (MIS-GC) and proposes a multiple-input symbol generalised differential Golden code (MIS-GD-GC) scheme. This scheme improves the error performance when compared to conventional differential MIS-GC and achieves a diversity order of 2(l)N(r) compared to the conventional Golden code, where l >= 1 is an integer, N-r is the number of receive antennas and 2(l) represents the number of multiple-input symbols in the MIS-GC system. We also derive the average bit error probability for the MIS-GD-GC scheme. The simulations of bit error rate (BER) compare very well to the derived theoretical bounds and show that the BER of MIS-GD-GC draws closer to that of coherent MIS-GC as the frame length increases. For instance, at a frame length of B=400, the error performance gap between MIS-GD-GC and its coherent counterpart is only 0.4 dB.

关键词： Fatty acids   weight   appetite   energy expenditure   diet induced thermogenesis  

摘要： The association between weight and chronic diseases is well defined. The quality and quantity of dietary fatty acids is an important external factor and appetite and energy expenditure, are important internal factors in determining body weight. On the other hand, dietary fatty acids composition can modulate appetite and energy metabolism, but not all fats are equal in producing metabolic responses. Given the accumulating evidence for differential effects of various dietary fatty acids, one important area of investigation is to scrutinize their roles in weight, appetite and energy expenditure modulation. There is substantial evidence to suggest that saturated fatty acids have a greater effect on appetite control, although in the long run may result in more weight gain than unsaturated fatty acids due to a weaker stimulation of energy expenditure. In contrast, mono-unsaturated fats do not have much effects on appetite control, but they can be beneficial in weight control over the long term due to stimulatory effects on energy expenditure. Interestingly, in case of poly unsaturated fats, including n-3 and n-6, their effect on increasing energy expenditure is aligned, but they act differently in controlling weight and appetite.

关键词： Functional differential equations   State-dependence   Integral inequality   Asymptotics   Lyapunov indirect method  

摘要： In this paper we study existence and asymptotic behaviors of solutions for mixed-type functional differenof state-dependent terms, it is so difficult to discuss its stability by Lyapunov direct method. Through an order-preserving transformation, we generalize Gronwall inequality to obtain boundedness and asymptotics of solutions. It can be regarded as an extension to Lyapunov indirect method. Moreover, we indicate that Krasnoselskii fixed point theorem also can be used to study existence of sign-changing solutions. Finally, we apply our method to iterative functional differential equations and provide two concrete examples. (c) 2021 Elsevier Inc. All rights reserved.

摘要： Motivation: The distinct functionalities of human tissues and cell types underlie complex phenotype-genotype relationships, yet often remain elusive. Harnessing the multitude of bulk and single-cell human transcriptomes while focusing on processes can help reveal these distinct functionalities. Results: The Tissue-Process Activity (TiPA) method aims to identify processes that are preferentially active or underexpressed in specific contexts, by comparing the expression levels of process genes between contexts. We tested TiPA on 1579 tissue-specific processes and bulk tissue transcriptomes, finding that it performed better than another method. Next, we used TiPA to ask whether the activity of certain processes could underlie the tissue-specific manifestation of 1233 hereditary diseases. We found that 21% of the disease-causing genes indeed participated in such processes, thereby illuminating their genotype-phenotype relationships. Lastly, we applied TiPA to single-cell transcriptomes of 108 human cell types, revealing that process activities often match cell-type identities and can thus aid annotation efforts. Hence, differential activity of processes can highlight the distinct functionality of tissues and cells in a robust and meaningful manner.

关键词： Dynamic light scattering  

摘要： Few techniques can reliably measure the dynamics of colloidal suspensions or other soft materials over a wide range of turbidities. Here we systematically investigate the capability of Differential Dynamic Microscopy (DDM) to characterise particle dynamics in turbid colloidal suspensions based on brightfield optical microscopy. We measure the Intermediate Scattering Function (ISF) of polystyrene microspheres suspended in water over a range of concentrations, turbidities, and up to 4 orders of magnitude in time-scales. These DDM results are compared to data obtained from both Dynamic Light Scattering (DLS) and Two-colour Dynamic Light Scattering (TCDLS). The latter allows for suppression of multiple scattering for moderately turbid suspensions. We find that DDM can obtain reliable diffusion coefficients at up to 10 and 1000 times higher particle concentrations than TCDLS and standard DLS, respectively. Additionally, we investigate the roles of the four length-scales relevant when imaging a suspension: the sample thickness L, the imaging depth z, the imaging depth of field DoF, and the photon mean free path l. More detailed experiments and analysis reveal the appearance of a short-time process as turbidity is increased, which we associate with multiple scattering events within the imaging depth of the field. The long-time process corresponds to the particle dynamics from which particle-size can be estimated in the case of non-interacting particles. Finally, we provide a simple theoretical framework, ms-DDM, for turbid samples, which accounts for multiple scattering.

关键词： Cytochrome b(6)f complex   drought stress   non-photochemical quenching   plant development   photosystem II   photosynthesis   resurrection plant   thylakoid membrane  

摘要： A group of vascular plants called homoiochlorophyllous resurrection plants evolved unique capabilities to protect their photosynthetic machinery against desiccation-induced damage. This study examined whether the ontogenetic status of the resurrection plant Craterostigma pumilum has an impact on how the plant responds to dehydration at the thylakoid membrane level to prepare cells for the desiccated state. Thus, younger plants (<4 months) were compared with their older (>6 months) counterparts. Ultrastructural analysis provided evidence that younger plants suppressed senescence-like programs that are realized in older plants. During dehydration, older plants degrade specific subunits of the photosynthetic apparatus such as the D1 subunit of PSII and subunits of the cytochrome b(6)f complex. The latter leads to a controlled down-regulation of linear electron transport. In contrast, younger plants increased photoprotective high-energy quenching mechanisms and maintained a high capability to replace damaged D1 subunits. It follows that depending on the ontogenetic state, either more degradation-based or more photoprotective mechanisms are employed during dehydration of Craterostigma pumilum. Younger resurrection plants mainly employ photoprotective mechanisms to prepare the photosynthetic apparatus for the desiccated state, whereas older plants mainly degrade specific subunits.

关键词： differential ion mobility   two-temperature theory   collision cross section   ion-solvent cluster   density functional theory  

摘要： Differential mobility spectrometry is a separation technique that may be applied to a variety of analytes ranging from small molecule drugs to peptides and proteins. Although rudimentary theoretical models of differential mobility exist, these models are often only applied to small molecules and atomic ions without considering the effects of dynamic microsolvation. Here, we advance our theoretical description of differential ion mobility in pure N-2 and microsolvating environments by incorporating higher order corrections to two-temperature theory (2TT) and a pseudoequilibrium approach to describe ion-neutral interactions. When comparing theoretical predictions to experimentally measured dispersion plots of over 300 different compounds, we find that higher order corrections to 2TT reduce errors by roughly a factor of 2 when compared to first order. Model predictions are accurate especially for pure N-2 environments (mean absolute error of 4 V at SV = 4000 V). For strongly clustering environments, accurate thermochemical corrections for ion-solvent clustering are likely required to reliably predict differential ion mobility behavior. Within our model, general trends associated with clustering strength, solvent vapor concentration, and background gas temperature are well reproduced, and fine structure visible in some dispersion plots is captured. These results provide insight into the dynamic ion-solvent clustering process that underpins the phenomenon of differential ion mobility.

关键词： 隐性信息   高频考点   解法探究   导数压轴题   解法探析   解题思路   高考试卷   双变量  

摘要： 历年高考试卷中的导数压轴题,都是命题专家的独具匠心之作.而双变量问题是其中的高频考点,高频考点之下必有变式,2021年全国卷导数压轴题其本身表述简洁,但解题的思想方法是灵活多样的,这有利于激发学生思维的灵活性.在解题中,若学生不能将题中的隐性信息识别转化,就无法打开解题思路,因此如何将所给条件进行转化成为解题的关键.本文对此类问题进行解法探究,总结处理此类问题的常用方法及基本思想,以期达到抛砖引玉之效.