A Review of the Calculation Formula for the Four-component Borehole Strainmeter and Application to Earthquake Cases

Based on the principle formula for the four-component strainmeters, we can directly obtain the specific plane strain, shear strain and azimuthal angle of the principal strain, and the maximum and minimum principal strains calculated afterwards are the indirect result. The problems of practicality of the sensitivity coefficients A and B of plane strain and shear strain are then discussed. Based on this idea, we analyzed the observation data of several four-component borehole strainmeters near the epicenter of the Yiliang M_S5.7 earthquake in 2012 and the Ludian M_S6.5 earthquake in 2014 in the Zhaotong area, Yunnan Province. The results show that the analysis based on the perspective of plane strain and shear strain has an obviously better effect than that based on the component readings, and can directly peel off the respective abnormality of the plane strain and shear strain. In addition, the correlation coefficient curves between measured data of two plane strains show significant anomalies which often occur several days before and during the earthquake.

Synthesis of Polysubstituted 1,4-Dihydropyridines via Four-component Reactions of Arylamine,Acetylenedicarboxylate, Aromatic Aldehyde and Ethyl Acetoacetate

An efficient synthetic protocol for the 1,4-diaryl-1,4-dihydropyridines was developed via the domino four-component reaction of arylamine,acetylenedicarboxylate,aromatic aldehyde and ethyl acetoacetate.The reaction mechanism involves the formation of β-enamino ester and its sequential Michael addition to arylidene acetoacetate.

Double-Peakon Solutions of Two Four-Component Camassa-Holm Type Equations

This paper is contributed to study two new integrable four-component systems reduced from a multi-component generation of Camassa-Holm equation. Some double peakon solutions of both systems are described in an explicit formula by the method of variation of constant for ordinary differential equations. These double peakon solutions are established in weak sense. The dynamic behaviors of the obtained double peakon solutions are illustrated by some figures.

Nickel-catalyzed carbonylative four-component 1,4-dicarbofunctionalization of 1,3-enynes

An efficient Ni-catalyzed four-component 1,4-carbocarbonylation of 1,3-enynes with activated alkyl halides and arylboronic acids under atmospheric pressure of CO is presented.By tuning the electronic and steric effects of alkyl radicals,both electronrich and electron-deficient 1,3-enynes were compatible with this cascade.This protocol features mild conditions,broad substrate scope,excellent functional group compatibility and facile gram-scale synthesis,providing a practical approach to the quaternary carbon center-containing allenyl ketones.Mechanistic study revealed that the acyl-NiIIspecies plays an important role in both the coupling and the alkyl radical generation processes.

Additive-free synthesis of S-substituted isothioureas via visible-light-induced four-component reaction ofα-diazoesters,aryl isothiocyanates,amines and cyclic ethers

An additive-free and environmentally friendly strategy has been realized for the construction of S-substituted isothioureas through visible-light-induced multicomponent reaction starting fromα-diazoesters,aryl isothiocyanates,amines and cyclic ethers.This methodology features simple operation,mild reaction conditions,favorable functional group tolerance,easily available starting materials and high efficiency.

An Efficient Synthesis of N-Substituted-3-aryl-3-（2-hydroxy-4,4- dimethyl-6-oxocyclohex-l-enyl）propanamides by Four-component Reaction in Aqueous Medium

A mild and efficient synthesis of N-substituted-3-aryl-3-（2-hydroxy-4,4-dimethyl-6-oxocyclohex-l- enyl）propanamides via four-component reaction of an aldehyde, amine, Meldrum＇s acid and 5,5-dimethylcyclo- hexane-1,3-dione in the presence of benzyltriethylammonium chloride （TEBAC） in aqueous medium is described. This method has the advantages of accessible starting materials, good yields, mild reaction conditions and eco- friendliness.

Satellite-Based Estimation of Daily Average Net Radiation under Clear-Sky Conditions

ABSTRACT Daily average net radiation （DANR） is an important variable for estimating evapotranspiration from satellite data at regional scales, and is used for atmospheric and hydrologic modeling, as well as ecosystem management. A scheme is proposed to estimate the DANR over large heterogeneous areas under clear-sky conditions using only remotely sensed data. The method was designed to overcome the dependence of DANR estimates on ground data, and to map spatially consistent and reasonably distributed DANR, by using various land and atmospheric data products retrieved from MODIS （Moderate Resolution Imaging Spectroradiometer） data. An improved sinusoidal model was used to retrieve the diurnal variations of downward shortwave radiation using a single instantaneous value from satellites. The downward shortwave component of DANR was directly obtained from this instantaneous value, and the upward shortwave component was estimated using satellite-derived albedo products. Four observations of air temperature from MOD07_L2 and MYD07_L2 data products were used to derive the downward longwave component of DANR, while the upward longwave component was estimated using the land surface temperature （LST） and the surface emissivity from MOD1 l_L2. Compared to in situ observations at the cropland and grassland sites located in Tongyu, northern China, the root mean square error （RMSE） of DANR estimated for both sites under clear-sky conditions was 37 W m-2 and 40 W m-2, respectively. The errors in estimation of DANR were comparable to those from previous satellite-based methods. Our estimates can be used for studying the surface radiation balance and evapotranspiration.

Co纳米粒子催化无溶剂条件下一锅四组分法高效合成1,4-二氢吡啶衍生物(英文)

A straightforward and general method has been developed for the synthesis of C5-unsubstitiuted 1,4-dihydropyridines by a reaction using dimedone, acetophenone, aromatic aldehydes, and ammonium acetate in the presence of a catalytic amount of Co nanoparticles as a heterogeneous and eco-friendly catalyst with high catalytic activity at room temperature under solvent-free conditions. This catalyst is easily separated by magnetic devices and can be reused without any apparent loss of activity for the reaction. In addition, it is very interesting that when using Co nanoparticles as a catalyst, spatially-hindered aldehydes such as 2-methoxy-, 2-fluoro-, and 2-chloro-aldehydes are suitable for this reaction.

One-step,synthesis of Hantzsch esters and polyhydroquinoline derivatives using new organocatalyst

Herein we report an efficient organocatalyst for the multicomponent Hantzsch reaction under mild condition.The product easily isolated by simple filtration and catalyst can be recovered.

Simultaneous Spectrophotometric Determination of Four Components including Acetaminophen by Taget Factor Analysis

UV Spectrophotometric Target Factor Analysis （TFA） was used for the simultaneous determination of four components （acetaminophen, guuaifenesin, caffeine, Chlorphenamine maleate） in cough syrup. The computer Frogram of TFA is based on VC＋＋ language. The difficulty of overlapping of absorption spectra of four compounds was overcome by this procedure. The experimental results show that the average recovery of each component is all in the range from 98.9% to 106.8% and each component obtains satisfactory results without any pre-separation.

Recent advances in the syntheses of pyrroles

The pyrrole moiety is an important structural motif in functional materials,natural products,and pharmaceuticals.More and more synthetic strategies toward pyrroles have emerged,where various efficient building blocks are developed and these synthons enable the syntheses of pyrroles with different numbers of components.However,no review specifically summarizes the syntheses of pyrroles according to the type and number of employed building blocks.To aid researchers to design appropriate substrates for pyrrole synthesis,herein we summarized the advances in pyrrole syntheses and classified these reactions into four categories according to the number of employed components,which may shed light on developing more efficient synthetic methods toward substituted pyrroles.

A simple and efficient approach to one-pot synthesis of mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates catalyzed by InCl_3

An efficient and straightforward procedure has been developed for the synthesis of highly substituted mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates via a one-pot, four-component domino reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in the presence of InCl3 （20 mol%） in MeOH at ambient temperature. The salient advantages of this method are mild reaction conditions, environmentally benign, high to excellent yields, shorter reaction times, easy operation and no column chromatographic separation.

Electrophoretic deposition of chitosan-bioglass^(■)-hydroxyapatite-halloysite nanotube composite coating

The composite coatings of chitosan(CS)-bioglass^(■)(BG)-hydroxyapatite(HA)-halloysite nanotube(HNT)were investigated and produced via electrophoretic deposition(EPD)technique.The utilization of CS as a dispersing,blending and charging agent for ceramic particles,including BG,HA and HNT,allowed the formation of CS-BG/HA/HNT composite,functionally graded composite(FGC)and bilayer film containing different layers.The results of scanning electron microscopy(SEM),energy-dispersive spectrometry(EDS),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)illustrate the composite in the form of the optimum distribution of ceramic components in the CS matrix with thickness of 28μm on titanium(Ti)substrate.Electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization tests indicate that the corrosion resistance of the coated sample increases in corrected simulated body fluid(C-SBF)at 37℃.Finally,the apatiteinducing ability of CS-BG-HA-HNT is proved by the formation of carbonated hydroxyapatite particles on composite coating in C-SBF.