Numerical Modeling of a Teeth-shaped Nano-plasmonic Waveguide Filter

In this paper, tooth-shaped and multiple-teeth-shaped plasmonic filters in the metal-insulator-metal (MIM) waveguides are demonstrated numerically. By introducing a three-port waveguide splitter, a modified model based on the multiple-beam-interference and the scattering matrix is given. The ransmittance spectrum as a function of teeth width, depth, period and period number are respectively addressed. The result shows the new structure not only performs the filtering function as well as MIM grating-like structures, but also is of submicrometer size for ultra-high integration and relatively easy fabrication.Comment: 21pages, 7 figure

Atmospheric pollen concentrations and chronic obstructive pulmonary disease (COPD) patients visits in Beijing: time series analysis using a generalized additive model

Abstract To investigate the correlation between the daily visits of chronic obstructive pulmonary disease (COPD) patients in hospital clinic and pollen concentrations in Beijing. We collected daily visits of COPD patients of Beijing Shijitan Hospital from April 1st, 2019 to September 30th, 2019. The relationship between pollen concentrations and COPD patient number was analyzed with meteorological factors, time trend, day of the week effect and holiday effect being controlled by the generalized additive model of time series analysis. R4.1.2 software was applied to generate Spearman correlation coefficient, specific and incremental cumulative effect curves of relative risks as well as the response and three-dimensional diagrams for the exposure lag effect prediction. The fitting models were used to predict the lag relative risk and 95% confidence intervals for specific and incremental cumulative effects of specific pollen concentrations. The number of COPD patients was positively correlated with pollen concentration. When pollen concentration increased by 10 grains/1000 mm2, the peak value of the specific cumulative effect appeared on day0, with the effect gone on day4 and a lag time of 4 days observed, whereas the incremental cumulative effect’s peak value was shown on day17, and the effect disappeared on day18, with a lag time of 18 days. The results showed that pollen concentration was not only positively correlated with the number of COPD patients, but also had a bimodal lag effect on COPD visits in the hospital at Beijing

A First-Principles Study of the Structural, Elastic, and Mechanical Characteristics of Mg₂Ni Subjected to Pressure Conditions

This study employs first-principles calculations to examine structural, elastic, and mechanistic relationships of Mg2Ni alloys under varying conditions of pressure. The investigation encompasses Young’s modulus, bulk modulus, shear modulus, Poisson’s ratio, and anisotropy index, as well as sound velocity, Debye temperature, and related properties. Our findings indicate that the lattice parameters of Mg2Ni in its ground state are in agreement with values obtained experimentally and from the literature, confirming the reliability of the calculated results. Furthermore, a gradual decrease in the values of the lattice parameters a/a0 and c/c0 is observed with increasing pressure. Specifically, the values for C13 and C33 decrease at a hydrostatic pressure of 5 GPa, while C11 and C13 increase when the external hydrostatic pressure exceeds 5 GPa. All other elastic constants exhibit a consistent increasing trend with increasing pressure between 0 and 30 GPa, with C11 and C12 increasing at a faster rate than C44 and C66. In the 0–30 GPa pressure range, Mg2Ni satisfies the mechanical stability criterion, indicating its stable existence under these conditions. Additionally, the Poisson’s ratio of Mg2Ni consistently exceeds 0.26 over a range of pressures from 0 to 30 GPa, signifying ductility and demonstrating consistency with the value of B/G. The hardness of Mg2Ni increases within the pressure range of 0–5 GPa, but decreases above 5 GPa. Notably, the shear anisotropy of Mg2Ni exhibits greater significance than the compressive anisotropy, with its anisotropy intensifying under higher pressures. Both the sound anisotropy and the Debye temperature of Mg2Ni demonstrate an increasing trend with rising pressure

Advances in Laser Drilling of Structural Ceramics

The high-quality, high-efficiency micro-hole drilling of structural ceramics to improve the thermal conductivity of hot-end parts or achieve high-density electronic packaging is still a technical challenge for conventional processing techniques. Recently, the laser drilling method (LDM) has become the preferred processing tool for structural ceramics, and it plays an irreplaceable role in the industrialized processing of group holes on structural ceramic surfaces. A variety of LDMs such as long pulsed laser drilling, short pulsed laser drilling, ultrafast pulsed laser drilling, liquid-assisted laser drilling, combined pulse laser drilling have been developed to achieved high-quality and high-efficiency micro-hole drilling through controlling the laser–matter interaction. This article reviews the characteristics of different LDMs and systematically compares the morphology, diameter, circularity, taper angle, cross-section, heat affect zone, recast layer, cracks, roughness, micro–nano structure, photothermal effect and photochemical reaction of the drilling. Additionally, exactly what processing parameters and ambient environments are optimal for precise and efficient laser drilling and their recent advancements were analyzed. Finally, a summary and outlook of the LDM technology are also highlighted

Investigating the <i>β</i>-Mg₁₇Al₁₂ Alloy under Pressure Using First-Principles Methods: Structure, Elastic Properties, and Mechanical Properties

Calculations of first principles were employed to explore the elastic constants of the β-Mg17Al12 intermetallic complex under pressure, along with several related physical parameters, including the bulk modulus, the shear modulus, Young’s modulus, Poisson’s ratio, and the anisotropy index. The volume of the β-Mg17Al12 crystal in the ground state was V0 = 1180.353 Å3, and the lattice parameter was 10.57 Å. This is in agreement with the available results in the literature, which indicate that the calculations were correct. The three independent elastic constants, C11, C12, and C44, increased with increasing pressure. The bulk modulus B, shear modulus G, and Young’s modulus E increased with increasing pressure, indicating that the bulk deformation resistance, shear deformation resistance, and stiffness of the β-Mg17Al12 phase increased with increasing pressure. The phase had a B/G > 1.75 and a Poisson’s ratio of ν > 0.26 and increased with pressure, indicating that the β-Mg17Al12 crystals were ductile and that the ductility increased with pressure. The Cauchy pressure C12–C44 increased with increasing pressure. The anisotropy coefficients A(100) and A(110) deviated further from 1, and the anisotropy increased. The electronic structure calculations showed that the total density of the states (TDOS) was achieved mainly by the Mg-3p and Al-3p states, and the total density of states moved toward the higher energy regions under pressure, with enhanced interatomic bonding, leading to an increase in the elastic constants and ultimately to an increase in each physical property with increasing pressure

Numerical investigation of entropy generation of turbulent flow in twisted tri-lobed tubes

Twisted tri-lobed tubes have garnered attention due to their exceptional heat transfer efficiency and straightforward fabrication. Existing literature lacks comprehensive assessments of the overall heat transfer performance of twisted tri-lobed tubes from the perspective of energy loss and irreversibility. This research aims to investigate entropy generation during turbulent water flow within twisted tri-lobed tubes, examining the influence of geometric parameters on local and average entropy production. Findings indicate that larger small circle radius (r) and straight lengths (l), coupled with smaller transition circle radius (R) and twist pitch lengths (p), result in diminished local and average heat transfer entropy production while enhancing local and average frictional entropy production, with heat transfer entropy generation dominating the overall entropy production. Additionally, with increasing Reynolds numbers, all twisted tubes demonstrate an increasing trend in average frictional entropy production, except for some cases (Case 1-Case 4) that exhibit an initial rise followed by a decline in average heat transfer entropy generation. Among the examined Reynolds range, Case 4 displays lower overall irreversibility compared to a plain tube. Following the second law of thermodynamics, Case 4 is preferred. The findings and methodology contribute to enhancing the thermodynamic evaluation of convective heat transfer in twisted tri-lobed tubes

<i>m</i>‑Phthalic Diamide-Linked Zinc Bisporphyrinate: Spontaneous Resolution of Its Crystals and Its Application in Chiral Recognition of Amino Acid Esters

A novel <i>m</i>-phthalic diamide-linked zinc bisporphyrinate [Zn₂-<b>1</b>] has been designed and synthesized. Its chiral crystalline samples have been spontaneously resolved by crystallization. Data for C₄₈H₂₉N₅OZn follow: tetragonal, <i>I</i>4₁, <i>a</i> = 17.809(2) Å, <i>b</i> = 17.809(2) Å, <i>c</i> = 27.080(8) Å, <i>V</i> = 8589 (3) ų, <i>Z</i> = 8. X-ray crystallography reveals the two porphyrin subunits are clockwise arranged in the solved structure. Each zinc atom is coordinated by four pyrrole nitrogens and the amide oxygen of the neighboring molecule. Through coordination bonds, it forms a helical chain with <i>P</i> configuration along the <i>c</i> axis. The overall crystal forms an unprecedented chiral bisporphyin coordination polymer. The chirality of the single crystals has been confirmed by CD spectroscopy. UV–vis and NMR spectroscopic studies suggested the molecule aggregates in solution. Such <i>m</i>-phthalic diamide-linked zinc bisporphyrinate shows a strong chiral recognition ability for amino acid ethyl esters. The amplitude value of the induced circular dichroism (ICD) (∼1900 cm^–1 M^–1) is around 10 times larger than the one observed for the oxalic amide-linked species (<i>Dalton Trans.</i> <b>2013</b>, <i>42</i>, 7651–7659). Further studies by ¹H NMR and UV–vis spectroscopies have revealed amino acid esters function as monodentate ligands, and [Zn₂-<b>1</b>] interacts with amino acid ethyl esters through coordination and hydrogen bonding interactions. The CD amplitude values have also shown dependence on the bulkiness of the side chain of amino acid esters. A possible chiral recognition mechanism has been proposed

Exploring the CO₂ Electrocatalysis Potential of 2D Metal–Organic Transition Metal–Hexahydroxytriquinoline Frameworks: A DFT Investigation

Metal–organic frameworks have demonstrated great capacity in catalytic CO2 reduction due to their versatile pore structures, diverse active sites, and functionalization capabilities. In this study, a novel electrocatalytic framework for CO2 reduction was designed and implemented using 2D coordination network-type transition metal–hexahydroxytricyclic quinazoline (TM–HHTQ) materials. Density functional theory calculations were carried out to examine the binding energies between the HHTQ substrate and 10 single TM atoms, ranging from Sc to Zn, which revealed a stable distribution of metal atoms on the HHTQ substrate. The majority of the catalysts exhibited high selectivity for CO2 reduction, except for the Mn–HHTQ catalysts, which only exhibited selectivity at pH values above 4.183. Specifically, Ti and Cr primarily produced HCOOH, with corresponding 0.606 V and 0.236 V overpotentials. Vanadium produced CH4 as the main product with an overpotential of 0.675 V, while Fe formed HCHO with an overpotential of 0.342 V. Therefore, V, Cr, Fe, and Ti exhibit promising potential as electrocatalysts for carbon dioxide reduction due to their favorable product selectivity and low overpotential. Cu mainly produces CH3OH as the primary product, with an overpotential of 0.96 V. Zn primarily produces CO with a relatively high overpotential of 1.046 V. In contrast, catalysts such as Sc, Mn, Ni, and Co, among others, produce multiple products simultaneously at the same rate-limiting step and potential threshold

Theoretical Study on the Structural, Elastic, Electronic and Thermodynamic Properties of Long-Period Superstructures h- and r-Al₂Ti under High Pressure

The formations of long-period superstructures strongly influence the properties of Al-rich L10-TiAl intermetallic alloys. To soundly understand the role of the superstructures in the alloys, fundamentals about them have to be known. In the present work, the structural, elastic, electronic and thermodynamic properties of h- and r-Al2Ti long-period superstructures under pressure up to 30 GPa were systematically investigated using first-principles calculations based on density functional theory. The pressure dependence of structural parameters, single-crystal elastic constants, polycrystalline elastic modulus, Cauchy pressures and elastic anisotropy were successfully calculated and discussed. The total and partial densities of states at different pressures were also successfully calculated and discussed. Furthermore, combining with quasi-harmonic approximation, the effects of the pressure on the temperature dependent volume, isothermal bulk modulus, thermal expansion coefficient, heat capacity and Gibbs free energy difference were successfully obtained and discussed. Our results were consistent with the available experimental and theoretical values

Table_1_Random forest algorithm for predicting postoperative delirium in older patients.DOCX

ObjectiveIn this study, we were aimed to identify important variables via machine learning algorithms and predict postoperative delirium (POD) occurrence in older patients.MethodsThis study was to make the secondary analysis of data from a randomized controlled trial. The Boruta function was used to screen relevant basic characteristic variables. Four models including Logistic Regression (LR), K-Nearest Neighbor (KNN), the Classification and Regression Tree (CART), and Random Forest (RF) were established from the data set using repeated cross validation, hyper-parameter optimization, and Smote technique (Synthetic minority over-sampling technique, Smote), with the calculation of confusion matrix parameters and the plotting of Receiver operating characteristic curve (ROC), Precision recall curve (PRC), and partial dependence graph for further analysis and evaluation.ResultsThe basic characteristic variables resulting from Boruta screening included grouping, preoperative Mini-Mental State Examination(MMSE), CHARLSON score, preoperative HCT, preoperative serum creatinine, intraoperative bleeding volume, intraoperative urine volume, anesthesia duration, operation duration, postoperative morphine dosage, intensive care unit (ICU) duration, tracheal intubation duration, and 7-day postoperative rest and move pain score (median and max; VAS-Rest-M, VAS-Move-M, VAS-Rest-Max, and VAS-Move-Max). And Random Forest (RF) showed the best performance in the testing set among the 4 models with Accuracy: 0.9878; Matthews correlation coefficient (MCC): 0.8763; Area under ROC curve (AUC-ROC): 1.0; Area under the PRC Curve (AUC-PRC): 1.0.ConclusionA high-performance algorithm was established and verified in this study demonstrating the degree of POD risk changes in perioperative elderly patients. And the major risk factors for the development of POD were CREA and VAS-Move-Max.</p