Outstanding Humidity Chemiresistors Based on Imine-Linked Covalent Organic Framework Films for Human Respiration Monitoring

Human metabolite moisture detection is important in health monitoring and non-invasive diagnosis.However,ultra-sensitive quantitative extraction of respiration information in real-time remains a great challenge.Herein,chemiresistors based on imine-linked covalent organic framework(COF)films with dual-active sites are fabricated to address this issue,which demonstrates an amplified humidity-sensing signal performance.By regulation of monomers and functional groups,these COF films can be pre-engineered to achieve high response,wide detection range,fast response,and recovery time.Under the condition of relative humidity ranging from 13 to 98%,the COFTAPB-DHTA film-based humidity sensor exhibits outstanding humidity sensing perfor-mance with an expanded response value of 390 times.Furthermore,the response values of the COF film-based sensor are highly linear to the relative humidity in the range below 60%,reflecting a quantitative sensing mechanism at the molecular level.Based on the dual-site adsorption of the(-C=N-)and(C-N)stretching vibrations,the revers-ible tautomerism induced by hydrogen bonding with water molecules is demonstrated to be the main intrinsic mechanism for this effective humidity detection.In addition,the synthesized COF films can be further exploited to effectively detect human nasal and oral breathing as well as fabric permeability,which will inspire novel designs for effective humidity-detection devices.

Value of Horizontal Inscribed Boards in Jiuxia Village from the Perspective of Farming-reading Culture

Horizontal inscribed boards are the main form for working people to long for and pursue a better life,and are an important carrier of traditional culture. From the perspectives of sociology,architecture and ecological folklore,this article analyzes the intrinsic relationships between people’s values,neighborhoods,customs and horizontal inscribed boards,and interprets the decorative value,human value and modern value of horizontal inscribed boards through preliminarily studying the cultural connotation of horizontal inscribed boards in Jiuxia Village.

Incommensurate-commensurate magnetic phase transition in double tungstate Li_(2)Co(WO_4)_(2)

Magnetic susceptibility,specific heat,and neutron powder diffraction measurements have been performed on polycrystalline Li_(2)Co(WO_4)_(2)samples.Under zero magnetic field,two successive magnetic transitions at T_(N1)~9.4 K and T_(N2)~7.4 K are observed.The magnetic ordering temperatures gradually decrease as the magnetic field increases.Neutron diffraction reveals that Li_(2)Co(WO_4)_(2)enters an incommensurate magnetic state with a temperature dependent k between T_(N1)and T_(N2).The magnetic propagation vector locks-in to a commensurate value k=(1/2,1/4,1/4)below T_(N2).The antiferromagnetic structure is refined at 1.7 K with Co2+magnetic moment 2.8(1),μ_B,consistent with our first-principles calculations.

Control of large linear magnetoelectricity in Co_(3)NiNb_(2)O_(9)

Magnetoelectric(ME)materials have caught worldwide attentions owing to their potential technological applications in ME switching devices or high-density data storage.However,realizing a sufficiently strong ME effect in one single material is always the key issue.Herein,we systematically investigate the Co_(3)NiNb_(2)O_(9),including the characterization of its crystalline structure,magnetism,specific heat,and pyroelectric properties.It is revealed that Co_(3)NiNb_(2)O_(9) exhibits a remarkable ME response below the magnetic phase transition temperature of TN-32 K.On one hand,the magnetic field-induced electric polarization is observed below TN while it is non-ferroelectric at no magnetic field.The evaluated ME coefficient is as large as 21.2 ps/m.On the other hand,the magnetization is significantly modulated by the applied electric field,with the inverse ME coefficient being 14.1 ps/m.The observed ME responses suggest a stable ME mutual control by the magnetic or electric field in Co_(3)NiNb_(2)O_(9).