Mechanical effects of acupuncture

Acupuncture, a physiotherapy, has been widely accepted all around the world. This study focuses on the influence of membrane structures and explains the acupuncture sensations from the aspect of mechanical properties. By mathematical modeling and numerical simulation, the scientific meaning of the acupuncture depth is investigated and phenomena and theory of acupuncture are discussed. The simulation results show that (a) the fascial structure is the main contributor to the force on the needle, the axial force will gradually increase before piercing the fascial, and suddenly decrease after piercing the fascial; (b) there is an inverse relationship between the needle radius and the maximum radial stress, which indicates that the needle should not be too sharp to cause local stress concentration and piece the fascia layer; and (c) the simulation results of comprehensively considering the static friction and sliding friction is identical with the experiment results. This study proposes a preliminary study of mechanical effects of acupuncture manipulation, clarifies key factors affecting the stress on the needle, and explains the objective requirement of acupuncture depth to effective treatment.     

Screening gas-phase chemical kinetic models: Collision limit compliance and ultrafast timescales

Detailed gas-phase chemical kinetic models are widely used in combustion research, and many new mechanisms for different fuels and reacting conditions are developed each year. Recent works have highlighted the need for error checking when preparing such models, but a useful community tool to perform such analysis is missing. In this work, we present a simple online tool to screen chemical kinetic mechanisms for bimolecular reactions exceeding collision limits. The tool is implemented on a user-friendly website, cloudflame.kaust.edu.sa, and checks three different classes of bimolecular reactions; (ie, pressure independent, pressure-dependent falloff, and pressure-dependent PLOG). In addition, two other online modules are provided to check thermodynamic properties and transport parameters to help kinetic model developers determine the sources of errors for reactions that are not collision limit compliant. Furthermore, issues related to unphysically fast timescales can remain an issue even if all bimolecular reactions are within collision limits. Therefore, we also present a procedure to screen ultrafast reaction timescales using computational singular perturbation. For demonstration purposes only, three versions of the rigorously developed AramcoMech are screened for collision limit compliance and ultrafast timescales, and recommendations are made for improving the models. Larger models for biodiesel surrogates, tetrahydropyran, and gasoline surrogates are also analyzed for exemplary purposes. Numerical simulations with updated kinetic parameters are presented to show improvements in wall-clock time when resolving ultrafast timescales.     

A new class of conformable spectral observers for signal reconstruction

In this work, the design of spectral observers for signal reconstruction based on Kalman filters is performed and evaluated. The conformable derivative and the beta‐derivative were used to design the Kalman filters. Both derivatives satisfy the same formulas of the classical derivation, eg, the chain rule. The derivative order, the Ricatti equation parameters, and the observers tuning parameters were optimized using an optimization algorithm based on the bat's echolocation behavior (Bat algorithm). The simulation results showed the advantages of using the proposed observers for the signal reconstruction.     

Critical Assessment of the DFT + U Approach for the Prediction of Vanadium Dioxide Properties

In a previous study (Stahl and Bredow, Chem. Phys. Lett. 2018, 695, 28–33), we have studied structural, energetic, and electronic properties of two vanadium dioxide VO₂ polymorphs with modified global and range-separated hybrid functionals. Since hybrid methods are computationally demanding, we evaluate the computationally more efficient DFT + U method in the present study. We assessed the widely used Dudarev PBE + U approach with a literature value of the effective Hubbard parameter U_eff = 3.4 eV. We compared the PBE + U results for the two VO₂ polymorphs with our previous results, a self-consistent hybrid functional sc-PBE0, and the meta-GGA functional SCAN. It was found that the PBE + U method yields a strongly distorted monoclinic phase and does not reproduce the metal-to-insulator transition of VO₂ correctly, even with modified values of U_eff. On the other hand, sc-PBE0 and SCAN describe the relative stability and the electronic structure of both polymorphs correctly and also provide reasonable lattice parameters. The functional SCAN yields the optimal balance between computational efficiency and accuracy. © 2019 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc.     

富里叶级数的收敛速度

对正弦和余弦富立叶级数,通过合并相邻同号项,使其重排成交错级数.讨论了重排形成的交错级数的敛散性.指出根据自变量x的不同取值,该交错级数可能是单调递减或周期递减的级数.按照莱布尼茨判定法提出了不同精度要求的级数项数的计算公式.选取一到三阶收敛的富立叶级数计算了不同比值精度及差值精度要求的级数项数.计算表明,在x的取值为2π的等分点时,富立叶级数的部分和随项数的增加单调地逼近其收敛值.在x的取值为其它点时,富立叶级数的部分和随项数的增加围绕收敛值上下变动,周期地逼近其收敛值.低收敛阶富立叶级数的收敛速度较慢.要达到0.01%的精度,一收敛阶富立叶级数需要数万项,二收敛阶富立叶级数也需要数百项.在不同计算点处,要达到相同的计算精度,需要的级数项数差别较大.     

Allostatic load as a complex clinical construct: A case‐based computational modeling approach

Allostatic load (AL) is a complex clinical construct, providing a unique window into the cumulative impact of stress. However, due to its inherent complexity, AL presents two major measurement challenges to conventional statistical modeling (the field's dominant methodology): it is comprised of a complex causal network of bioallostatic systems, represented by an even larger set of dynamic biomarkers; and, it is situated within a web of antecedent socioecological systems, linking AL to differences in health outcomes and disparities. To address these challenges, we employed case‐based computational modeling (CBM), which allowed us to make four advances: (1) we developed a multisystem, 7‐factor (20 biomarker) model of AL's network of allostatic systems; (2) used it to create a catalog of nine different clinical AL profiles (causal pathways); (3) linked each clinical profile to a typology of 23 health outcomes; and (4) explored our results (post hoc) as a function of gender, a key socioecological factor. In terms of highlights, (a) the Healthy clinical profile had few health risks; (b) the pro‐inflammatory profile linked to high blood pressure and diabetes; (c) Low Stress Hormones linked to heart disease, TIA/Stroke, diabetes, and circulation problems; and (d) high stress hormones linked to heart disease and high blood pressure. Post hoc analyses also found that males were overrepresented on the High Blood Pressure (61.2%), Metabolic Syndrome (63.2%), High Stress Hormones (66.4%), and High Blood Sugar (57.1%); while females were overrepresented on the Healthy (81.9%), Low Stress Hormones (66.3%), and Low Stress Antagonists (stress buffers) (95.4%) profiles. © 2015 Wiley Periodicals, Inc. Complexity 21: 291–306, 2016     

A computational method for geometric optimization of enhanced heat transfer devices based upon entropy generation minimization

A computational fluid dynamics‐based optimization methodology is developed, appropriate for the geometric optimization of enhanced heat transfer devices based upon the principle of entropy generation minimization, in which the objective function is evaluated from a flow field obtained by computational simulation. A quasi‐Newton optimization procedure is employed, with computation of the objective function gradients based upon a finite difference approach. The optimization procedure is developed to be general with regard to the choice of objective function, the details of the problem under consideration, and the computational methodology employed in solving the fluid flow and heat transfer problems. A novel implementation of a Taylor series‐based procedure for the fast solution of nearby problems is presented, which is found to greatly benefit the efficiency of the present methodology. Finally, a numerical experiment is presented, illustrating the use of the present method in the geometric optimization of a practical enhanced heat transfer device on the basis of the criterion of entropy generation minimization. The optimization of the fin spacing of a simple plate fin heat sink is considered, and a comparison of the computational results with results obtained by analytical optimization based upon empirical friction factor and Nusselt number correlations is given. Copyright © 2012 John Wiley & Sons, Ltd.     

Electric field assisted oxygen removal from the basal plane of the graphitic material

We provide a novel strategy to eliminate the epoxy group from the basal plane of graphene platelets. Given that the current reduction methods are unsatisfactory to clean the epoxides or sometimes cause undesirable structure deformations, the proposed strategy restores the original hexagonal carbon network without creating other new defects. To the best of our knowledge, the electric field mediated graphene oxide (GO) reduction has not yet been systematically investigated. The capability would permit the improvement of existing GO reduction methods and assist in the fabrication of high‐quality graphitic materials. © 2012 Wiley Periodicals, Inc.     

A novel molecularly imprinted method with computational simulation for the affinity isolation and knockout of baicalein from Scutellaria baicalensis

A novel molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization with baicalein (BAI) as the template and used as solid‐phase extraction (SPE) adsorbent, aiming at the affinity isolation and selective knockout of BAI from Scutellaria baicalensis Georgi (SB). We used computational simulation to predict the optimal functional monomer, polymerization solvent and molar ratio of template to functional monomer. Characterization and performance tests revealed that MIP exhibited uniform spherical morphology, rapid binding kinetics, and higher adsorption capacity for BAI compared with nonimprinted polymer (NIP). The application of MIP in SPE coupled with high‐performance liquid chromatography to extract BAI from SB showed excellent recovery (94.3%) and purity (97.0%). Not only the single BAI compound, but also the BAI‐removed SB extract was obtained by one‐step process. This new method is useful for isolation and knockout of key bioactive compounds from herbal medicines. Copyright © 2015 John Wiley & Sons, Ltd.