Comprehensive Benefit Evaluation Method of Mountain Flood Disaster Prevention and Control in Jiangxi Province Based on Matter-Element Extension Model

Taking the mountain flood disaster prevention and control project in Jiangxi province as the research object, the evaluation period is 2010-2015, and 29 evaluation indexes are selected from 7 aspects. In this paper, game theory is introduced to optimize the subjective and objective weights of the index, and the comprehensive weights are obtained by normalization. The results show that the eigenvalues of the grade variables of benefit evaluation decreased from 3.43 to 2.03, indicating that the project of mountain flood disaster prevention and control in Jiangxi province brings into play the benefits year by year, and the eigenvalues tend to decrease steadily after 2012, it is consistent with the changes of various engineering measures and non-engineering measures in the project.

Full-temperature covered switching material with triple optic-dielectric states in a lead-free hybrid perovskite

Optic-electric responsive materials have attracted much attention for their applications in temperaturesensing,actuators,and memory switches.However,it is a challenge to integrate various functions to form multifunctional responsive materials.As molecule-based hybrid materials usually consist of organic and inorganic components,the introduction of multiple functions can be achieved through structural construction.Thus far,even though fulltemperature cover is required for device applications,fulltemperature covered multi-switchable hybrid materials have rarely been successfully synthesized.Herein,the dynamic[(CH3)3NOH]+cation and luminous center Mn(II)were introduced to form a hybrid material[(CH3)3NOH][Mn Cl3],showing multiple temperature-responsive behaviors.Upon temperature change,it exhibits multi-state dielectric switching response and intensity or peak shift response of luminous in full-temperature range(low,room,and high temperatures).These responsive behaviors are triggered by the motion or reorientation of[(CH3)3NOH]+cations and inorganic framework.Overall,the switchable photoelectric material has potential applications in multiple encrypted storage and sensor devices.

Tunable phase transition, band gap and SHG properties by halogen replacement of hybrid perovskites [(thiomorpholinium)PbX_(3), X = Cl,Br,I]

By the replacement of halogen anion,three new multifunctional organic-inorganic hybrid perovskites(thiomorpholinium)PbX_(3)(X=Cl,Br,I)were successfully synthesized and underwent reversible struc-tural transformation above room temperature,accompanied by the anomalous change of dielectric con-stant.With the adjustment of the halogen anion from Cl to I in the inorganic skeleton,the space group is transformed from centrosymmetric space group P2_(1)/c((thiomorpholinium)PbCl_(3))to chiral one P2_(1)2_(1)2_(1)((thiomorpholinium)PbBr3,(thiomorpholinium)PbI_(3))at room temperature.The ordered-disordered tran-sition of organic cations and the change of hydrogen bonds with the increase of temperature lead to above-room-temperature phase transitions.Ultraviolet absorption and second-harmonic generation(SHG)measurements confirmed that both the band gap and SHG activity of(thiomorpholinium)PbX_(3)(X=Cl,Br,I)crystals were tunable.The band gaps reveal a broadening trend with 3.532 e V,3.410 e V and 3.175 e V along the Cl→Br→I series.This work provides an effective molecular design for multifunctional organic-inorganic perovskites.

High-temperature dielectric switch and second harmonic generation integrated in a stimulus responsive material

Stimulus re s ponsive materials can provide a variety of desirable properties in one equipment unit,such as optoelectronic devices,data communications,actuators,memories,sensors and capacitors.However,it remains a large challenge to design such stimulus responsive materials,especially functional materials having both dielectric switch and second harmonic generation(SHG).Here,a new stimuli-responsive switchable material [(CH_(3))_(3)N(CH_(2))_(2)Cl]_(2)]Mn(SCN)_(4)(H_(2)O)_(2)] was discovered as a potential secondharmonic generation(SHG) dielectric switch.It is worth noting that it has SHG characteristics before and after undergoing reversible high-temperature phase transitions.In this work,we successfully refined the tetramethylammonium cation to obtain a quasi-spherical cation,which is tetramethylchloroethylamine(TMCEM) cation.By substituting H with a halogen,the increased steric hindrance of the molecular makes energy barrier increased,resulting in the reversible high-temperature phase transition.At the same time,the interactions of quasi-spherical cations and [Mn(SCN)_(4)(H_(2)O)_(2)]^(2-) anions affect a noncentrosymmetric structure to induce the SHG effect.These findings provide a new approach to design novel functional switch materials.