Chemically Influenced Self-Preservation Kinetics of CH4 Hydrates below the Sub-Zero Temperature

The self-preservation property of CH4 hydrates is beneficial for the transportation and storage of natural gas in the form of gas hydrates. Few studies have been conducted on the effects of chemicals (kinetic and thermodynamic promoters) on the self-preservation properties of CH4 hydrates, and most of the available literature is limited to pure water. The novelty of this work is that we have studied and compared the kinetics of CH4 hydrate formation in the presence of amino acids (hydrophobic and hydrophilic) when the temperature dropped below 0 °C. Furthermore, we also investigated the self-preservation of CH4 hydrate in the presence of amino acids. The main results are: (1) At T < 0 ℃, the formation kinetics and the total gas uptake improved in the presence of histidine (hydrophilic) at concentrations greater than 3000 ppm, but no significant change was observed for methionine (hydrophobic), confirming the improvement in the formation kinetics (for hydrophilic amino acids) due to increased subcooling; (2) At T = −2 °C, the presence of amino acids improved the metastability of CH4 hydrate. Increasing the concentration from 3000 to 20,000 ppm enhanced the metastability of CH4 hydrate; (3) Metastability was stronger in the presence of methionine compared to histidine; (4) This study provides experimental evidence for the use of amino acids as CH4 hydrate stabilizers for the storage and transportation of natural gas due to faster formation kinetics, no foam during dissociation, and stronger self-preservation.

M♮-Convexity and Its Applications in Operations

A new approach for structural analysis of operations models with substitutability structures. In many operations models with substitutability structures, one often ends up with parametric optimization models that maximize submodular objective functions, and it is desirable to derive structural properties including monotone comparative statics of the optimal solutions or preservation of submodularity under the optimization operations. Yet, this task is challenging because the classical and commonly used results in lattice programming, applicable to optimization models with supermodular objective function maximization, do not apply. Using a key concept in discrete convex analysis, M♮-convexity, Chen and Li establish conditions under which the optimal solutions are nonincreasing in the parameters and the preservation property holds for parametric maximization models with submodular objectives, together with the development of several new fundamental properties of M♮-convexity. Their approach is powerful as demonstrated by applications in a classical multiproduct stochastic inventory model and a portfolio contract model.

Synthesis of carbon dots with antiphage activity using caffeic acid

Recent studies on preservation property in the field of materials science suggest that a newly synthesized material can retain the biological properties of the raw material. Still, further study is...

Dispersive order comparisons on extreme order statistics from homogeneous dependent random vectors

In this paper, we investigate sufficient conditions for preservation property of the dispersive order for the smallest and largest order statistics of homogeneous dependent random vectors. Moreover, we establish sufficient conditions for ordering with the dispersive order the largest order statistics from dependent homogeneous samples of different sizes.

9 Interim Measures of Protection/Emergency Arbitrator Procedures: (Article 23 and Appendix III)

This chapter addresses the subject of interim measures of protection, including emergency arbitrator procedures. Interim measures provide means to parties to preserve the status quo as between themselves pending the resolution of their dispute. Article 23 of the CIETAC Rules sets forth some general provisions on conservatory and interim measures in the context of CIETAC arbitration, covering such aspects as conservatory measures from PRC Court (Article 23.1), emergency reliefs from emergency arbitrator (Article 23.2), and interim measures from arbitral tribunal (Article 23.3). The interim measures available from the PRC court are limited to three types: evidence preservation; property preservation; and conduct preservation. Meanwhile, contained in Appendix III of the CIETAC Rules are detailed provisions relating to emergency arbitrator procedures.

A mass conserving mixed stress formulation for the Stokes equations

We propose stress formulation of the Stokes equations. The velocity $u$ is approximated with $H(\operatorname{div})$-conforming finite elements providing exact mass conservation. While many standard methods use $H^1$-conforming spaces for the discrete velocity $H(\operatorname{div})$-conformity fits the considered variational formulation in this work. A new stress-like variable $\sigma $ equalling the gradient of the velocity is set within a new function space $H(\operatorname{curl} \operatorname{div})$. New matrix-valued finite elements having continuous ‘normal-tangential’ components are constructed to approximate functions in $H(\operatorname{curl} \operatorname{div})$. An error analysis concludes with optimal rates of convergence for errors in $u$ (measured in a discrete $H^1$-norm), errors in $\sigma $ (measured in $L^2$) and the pressure $p$ (also measured in $L^2$). The exact mass conservation property is directly related to another structure-preservation property called pressure robustness, as shown by pressure-independent velocity error estimates. The computational cost measured in terms of interface degrees of freedom is comparable to old and new Stokes discretizations.