Multiple-parameter Linear Regression Research Articles

Ytterbium-Doped Lead-Halide Perovskite Nanocrystals: Synthesis, Near-Infrared Emission, and Open-Source Machine Learning Model for Prediction of Optical Properties.

Lead-halide perovskite nanocrystals are an attractive class of materials since they can be easily fabricated, their optical properties can be tuned all over the visible spectral range, and they possess high emission quantum yields and narrow photoluminescence linewidths. Doping perovskites with lanthanides is one of the ways to widen the spectral range of their emission, making them attractive for further applications. Herein, we summarize the recent progress in the synthesis of ytterbium-doped perovskite nanocrystals in terms of the varying synthesis parameters such as temperature, ligand molar ratio, ytterbium precursor type, and dopant content. We further consider the dependence of morphology (size and ytterbium content) and optical parameters (photoluminescence quantum yield in visible and near-infrared spectral ranges) on the synthesis parameters. The developed open-source code approximates those dependencies as multiple-parameter linear regression and allows us to estimate the value of the photoluminescence quantum yield from the parameters of the perovskite synthesis. Further use and promotion of an open-source database will expand the possibilities of the developed code to predict the synthesis protocols for doped perovskite nanocrystals.

Plasma synthesis of ammonia by asymmetric electrode arrangement

ABSTRACT The plasma reactors are of great interest in ammonia synthesis because of their green performance, small-scale process capabilities, and various design and application options. The purpose of this research is to synthesize water-soluble ammonia by plasma electrolysis which utilizes nitrogen atmospheric pressure plasma generated by DC discharge. Then, we investigate the influence of the plasma characteristics such as the electron temperature and density on the resultant ammonia concentration. For this purpose, the model of the Hoffman electrolysis apparatus was designed for separating the anodic and the cathodic parts, producing plasma, and finally interacting with an aqueous solution surface. This procedure allows us to compare the mechanism of the classical electrolysis with plasma electrolysis. The concentration of synthesized ammonia resulting from the reaction of active species in the interaction between plasma and the liquid surface on the cathode side of the device was obtained. The plasma electron temperature and density were measured by the standard Boltzmann plot method and the Stark broadening of via optical emission spectroscopy (OES), respectively, and their effects on the interaction between plasma and the water surface were investigated, which leads to nitrite and ammonia synthesis. The intensity of the emitted light varied as the discharge voltage was increased according to 8kV, 9kV, 10kV, and 11kV. As a result, the plasma electron temperature, density, and the synthesis of additional water-soluble ammonia parameters increase. Multiple parameter linear regression was used to evaluate the effect of varying the voltage on these parameters, which was positive.

Screening the main factors affecting phthalate esters adsorption on soils, humic acid, and clay organo-mineral complexes

Phthalate esters (PAEs) are one of the most frequently detected organic pollutants in soils. In this work, the adsorption behaviors of di-ethyl phthalate (DEP) and dibutyl phthalate (DBP) on soils, humins (HM) and Clay organo-mineral complexes (Clay-OM) from four regions in China, Changchun (CC), Cangzhou (CZ), Yinchuan (YC), and Changsha (CS) were studied. The surface and structural properties of these sorbents were characterized using Brunauer-Emmett-Teller specific surface area, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and 13C nuclear magnetic resonance methods. The results showed that the CC soil has the largest pore volume (PV) and specific surface area (SSA). PV, SSA, and aliphatic carbon content of the samples ranked as Clay-OM>HM>soil. Adsorption experiments indicated that the Clay-OM exhibited the strongest adsorption affinity for both DBP and DEP, followed by HM, and then the soil samples. Furthermore, DEP and DBP adsorption amounts on the samples declined as follows: CC>CS>CZ>YC. To illustrate the dominant mechanisms for PAEs adsorption onto soil, the soil organic carbon content normalized adsorption coefficient (LogKoc) was correlated with several possible parameters using multiple parameter linear regression and significance testing. The R2 values of the DBP and DEP in multi-regression equations were 0.825 and 0.741 respectively, and the significance test suggested that pore structure and specific surface area had crucial influences on the adsorption progress.

The Relationship between Tropical Cyclones at Genesis and Their Maximum Attained Intensity

Despite recent improvements made to tropical cyclone intensity predictions, this study investigates a different approach than those attempted thus far. Here, the overall environmental setup at genesis is evaluated to determine whether it predisposes a storm to reach its future maximum intensity. Variables retrieved from ERA-Interim are used to generate storm-centered composites at the time of genesis for Atlantic basin, main development region TCs from 1979–2015. Composites are stratified by their maximum attained intensity: tropical depressions (GTD), tropical storms (GTS), minor hurricanes (GMN), or major hurricanes (GMJ). A multiple-parameter linear regression is then used to associate the eventual attained intensity of tropical cyclone to the obtained variables at genesis. The regression has an adjusted r2 of 0.39, which indicates that a statistical relationship is present. Regression coefficients, along with the spatial distribution of variables in the storm-centered composites, indicate that storms that reach higher intensities are associated at genesis with stronger, more compact, low-level vortices, better-defined outflow jets, a more compact region of high midlevel relative humidity, and higher atmospheric water vapor content.

Efficient Rank-Adaptive Least-Square Estimation and Multiple-Parameter Linear Regression Using Novel Dyadically Recursive Hermitian Matrix Inversion

Least-square estimation (LSE) and multiple-parameter linear regression (MLR) are the important estimation techniques for engineering and science, especially in the mobile communications and signal processing applications. The majority of computational complexity incurred in LSE and MLR arises from a Hermitian matrix inversion. In practice, the Yule-Walker equations are not valid, and hence the Levinson-Durbin algorithm cannot be employed for general LSE and MLR problems. Therefore, the most efficient Hermitian matrix inversion method is based on the Cholesky factorization. In this paper, we derive a new dyadic recursion algorithm for sequential rank-adaptive Hermitian matrix inversions. In addition, we provide the theoretical computational complexity analyses to compare our new dyadic recursion scheme and the conventional Cholesky factorization. We can design a variable model-order LSE (MLR) using this proposed dyadic recursion approach thereupon. Through our complexity analyses and the Monte Carlo simulations, we show that our new dyadic recursion algorithm is more efficient than the conventional Cholesky factorization for the sequential rank-adaptive LSE (MLR) and the associated variable model-order LSE (MLR) can seek the trade-off between the targeted estimation performance and the required computational complexity. Our proposed new scheme can benefit future portable and mobile signal processing or communications devices.

Effect of coarse aggregate characteristics on concrete rheology

In the present study, concrete was considered as a two-phase material, consisting of coarse aggregate (CA) and mortar. Coarse aggregate properties were characterized by fineness, uncompacted void and friction angle. The combined effects of CA characteristics and mix design on the rheological properties of the corresponding concrete were investigated using a portable IBB concrete rheometer. Experimental results indicated that a higher CA and fine aggregate content normally result in higher concrete rheological parameters (yield stress and viscosity). For a given type and amount of mortar, concrete yield stress and viscosity generally increase with the uncompacted void content and friction angle but decreased with the size (or fineness) of CA. Well graded CA, generally having low uncompacted void content, provides concrete with considerably reduced yield stress and viscosity when compared with single-sized CA. In addition, a multiple-parameter linear regression analysis was conducted to evaluate how different CA characteristics (fineness, uncompacted void and friction angle) and mix design parameters (mortar composition, and CA volume fraction) affect concrete rheological behavior.

Increase of anthropogenic CO2 in the Pacific Ocean over the last two decades

Abstract The multiple-parameter linear regression method (Monitoring global ocean carbon inventories. Ocean Observing System Development Panel, Texas AM Global Biogeochem. Cycles 13 (1999) 179) is used to compare inorganic carbon data from the GEOSECS CO 2 survey in the Pacific Ocean in 1973 to the WOCE/JGOFS global CO 2 survey in the 1990s. A model of total dissolved inorganic carbon (DIC) as a function of five variables (AOU, θ , S, Si, and PO 4 ) has been developed from the recent CO 2 survey data (namely CGC91 and CGC96) in the Pacific Ocean. After correcting for a systematic DIC offset of −30.3±7 μmol kg −1 from the GEOSECS data, the residual DIC based on this model as computed from GEOSECS data has been used to estimate the anthropogenic CO 2 penetration in the Pacific Ocean. In the Northeast Pacific, we obtained an increase of CO 2 of 21.3±7.9 mol m −2 over the period from GEOSECS in 1973 to CGC91 in 1991. This gives a mean anthropogenic CO 2 uptake rate of 1.3±0.5 mol m −2 yr −1 over this 17 year time period. In the South Pacific, north of 50°S between 180° and 120°W region, the integrated anthropogenic CO 2 inventory is estimated to be 19.7±5.7 mol m −2 over the period from GEOSECS in 1974 to CGC96 in 1996. The equivalent mean CO 2 uptake rate is estimated to be 0.9±0.3 mol m −2 yr −1 over the 22 years. These results are compared with the isopycnal method (Nature 396 (1998) 560) to estimate the anthropogenic CO 2 signal in the Northeast Pacific (30°N, 152°W) at the crossover region between CGC91 and GEOSECS. The results of the isopycnal method are consistent with those derived from the MLR method. Both methods show an increase in anthropogenic CO 2 inventory in the ocean over two decades that is consistent with the increase expected if the ocean uptake has kept pace with the atmospheric CO 2 increase.

Competitive binding of 7-substituted-2,3-dichlorodibenzo-p-dioxins with human placental Ah receptor—A QSAR analysis

The competitive binding affinities of thirteen 7-substituted-2,3-dichlorodibenzo-p-dioxins to the human placental cytosolic aryl hydrocarbon (Ah) receptor were determined using [ 3 H]2,3,7,8 tetrachlorodibenzo-p- dioxin as the radioligand. Multiple parameter linear regression analysis of the competitive binding ec 50 values for these compounds gave the following equation: p ec 50( M) = 6.246 + 1.632 π − 1.764 σ 0 m + 1.282 HB where π, σ 0 m and HB are the physiochemical parameters for substituent lipophilicity, meta-directing electronegativity, and hydrogen bonding capacity respectively. The 7-t-butyl- and 7-phenyl-2,3-dichlorodibenzo-p-dioxins were treated as outliers for the derivation of this equation, and these results suggest that only substituents with van der Waals' volumes < 40 cm 3/mol were accommodated in the receptor binding site. The equations previously derived from the binding of the 7-substituted-2,3-dichlorodibenzo-p-dioxins to the rat, mouse, guinea pig and hamster hepatic cytosolic receptor were different than the correlation obtained using human placental receptor and provide further evidence for the interspecies differences in the molecular and binding properties of the Ah receptor protein.

7-Substituted-2,3-dichlorodibenzo- p-dioxins as competitive ligands for the Ah receptor: Quantitative structure-activity relationships (QSARs) and a comparison of human receptor with Ah receptor from rodents

The competitive binding affinities of thirteen 7-substituted-2,3,-dichlorodibenzo- p-dioxins to the human Ah placental cytosolic Ah receptor were determined versus [ 3 H]-2,3,7,8- tetrachlorodibenzo-p- dioxin (TCDD) as the radioligand. Multiple parameter linear regression analysis of the competitive binding EC 50 values for these compounds gave the following equation: pEC 50 (M) =6.246+1.632 π − 1.764σ m° + 1.282 HB were π is the substituent lipophilicity, σ m° the meta-directing electronegativity and HB the hydrogen binding capacity. The equation obtained using human placental receptor was different than correlations previously derived for the binding of the same series of compounds to the rat, mouse, guinea pig or hamster cytosolic Ah receptor, providing further evidence for interspecies differences in the properties of the Ah receptor protein.

Substituted polychlorinated dibenzofuran receptor binding affinites and aryl hydrocarbon hydroxylase induction potencies — A QSAR analysis

The rat hepatic cytosolic receptor binding affinities of 8-substituted 2,3-dichlorodibenzofurans and 8-substituted 2,3,4-trichlorodibenzofurans have been measured. The EC 50-value for each compound was determined by dose-response competitive displacement of 2,3,7,8-[ 3H]tetrachlorodibenzo- p-dioxin (TCDD). Multiple parameter linear regression analysis of the data using several substituent parameters [lipophilicity (π), hydrogen bonding (HB), electronegativity ( σ 0 p), STERIMOL ( ΔB 5)] demonstrated that for both sets of ligands, the binding affinities were dependent on substituent π-values. The equations derived for the 8-substituted 2,3,4-trichlorodibenzofurans (a) and 8-substituted 2,3-dichlorodibenzofurans (b) were log( 1 EC 50 )=1.09π+5.77 log( 1 EC 50 )=1.10π+5.19 remarkably similar, moreover the relatively bulky t-butyl substituent was treated as an outlier for both calculations. The in vitro induction of aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD) in rat hepatoma H-4-II E cells by both sets of ligands demonstrated that there was not a rank order correlation between induction potencies and receptor binding affinities for these compounds. Analysis of the data for the 8-substituted 2,3-dichlorodibenofurans demonstrated that the monooxygenase enzyme induction was dependent on substituent lipophilicity and a STERIMOL ( ΔB 5) factor which is related to log( 1 EC 50 ) AHH=0.80π+0.87θB 5−0.35(θB 5) 2+4.63 log( 1 EC 50 ) AHH=0.76π−1.11θB 5+2.23ω °p+6.78 substituent width. In contrast, the equation for the 8-substituted 2,3,4-trichlorodibenzofurans also included a substituent σ 0 p Hammett constant. The results indicate that although the binding affinities of the two sets of ligands are dependent only on substituent π-values, their enzyme induction activities are both substituent and chlorine substitution pattern-dependent.

Properties of the 2,3,7,8-TCDD receptor- a QSAR approach

The Ah or 2,3,7,8-TCDD receptor protein plays an important role in mediating the biologic, toxic and genotoxic effects of aryl and halogenated aryl hydrocarbons. An assessment of the physicochemical parameters which facilitate ligand: receptor interactions was determined by multiple parameter linear regression analysis of the relative receptor binding affinities of a series of 7-substituted-2,3-dichlorodibenzo-p-dixoins (Eq 1), 8-substituted-2,3-di (Eq. 2) and 2,3,4-trichlorodibenzofurans (Eq 3). The results demonstrate that substituent lipophilicity (π) and molecular volumes were Eq. 1 log (I/EC 50) = 1.24 π + 6.10 Eq. 2 log (I/EC 50) = 1.10 π + 5.19 Eq. 3 log (I/EC 50) = 1.09 π + 5.77 the major determinant factors governing interactions between the rat hepatic cytosolic receptor protein and the diverse substituted ligands. It has been shown that there are marked differences in species sensitivity to 2,3,7,8-TCDD (i.e. guinea pig > rat ∼ maice > hamster) although hepatic receptor levels in these species are comparable. QSAR analysis of the receptor binding EC 50 data for the 7-substituted-2,3-dichlorodibenzo-p-dioxins using rat (Eq. 1), mouse (Eq. 4), guinea pig (Eq. 5) and hamster (Eq. 6) hepatic cytosol demonstrated that there were significant differences in these equations. However it was also noted that Eq. 4 log (I/EC 50) = 0.95 + 0.93 E s + 5.28 Eq. 5 log (I/EC 50) = 0.94 + 0.579 σ p + 6.13 Eq. 6 log (I/EC 50) = 0.70 + 1.227 σ p + 6.38 physicochemical factors which are important for ligand-receptor interactions were identical for the most sensitive (guinea pig) and least sensitive (hamster) species. These results indicate that events which follow the initial ligand-receptor interaction must be the major factors which determine species sensitivity to 2,3,7,8-TCDD.