Seasonal dynamics and impact factors of urban forest CO2 concentration in Harbin,China

CO2 concentrations in different plant communities （larch, birch, lilac, and grassland） were measured during the growing season in the Heilongjiang Forest Botanical Garden to study diurnal variation, seasonal and annual dynamics and factors that impact CO2 concentration in different spaces. CO2 concentration in different communities in green lands had an obvious diurnal variation, chronically decreasing, and temperature influenced the lilac area and the grassland. Seasonally, CO2 was lowest in the larch green land （344.03 ±23.03 μmol/mol） and highest in the grassland （360.13 ± 22.43 μmol/mol）. The overall trend in CO2 concentration was autumn 〉 spring 〉 summer; temperature is the main factor controlling variation in CO2 concentrations during the growing season; the CO2 concentration at the larch, birch, lilac, and grassland types of sites was negatively correlated with land surface temperature and air temperature, and the CO2 concentration at the larch and birch sites was positively correlated with atmospheric pressure. Without any obvious annual change law, further study and observation are needed.

Heteroatom substitution-induced asymmetric A–D–A type non-fullerene acceptor for efficient organic solar cells

Research on asymmetric A–D–A structured non-fullerene acceptors has lagged far behind the development of symmetric counterpart.In this contribution,by simply replacing one sulfur atom in indacenodithiophene unit with a selenium atom,an asymmetric building block Se PT and a corresponding asymmetric non-fullerene acceptor Se PT-IN have been developed.Asymmetric Se PT-IN achieved a high efficiency of 10.20% in organic solar cells when blended with PBT1-C,much higher than that of symmetric TPT-IN counterpart(8.91%).Our results demonstrated an effective heteroatom substitution strategy to develop asymmetric A–D–A structured non-fullerene acceptors.

Synergy of porous structure and cation doping in Ta3N5 photoanode towards improved photoelectrochemical water oxidation

Herein,a cross-linked porous Ta3N5 film was prepared via a simple solution combustion route followed by a high-temperature nitridation process for photoelectrochemical(PEC) water oxidation.Meanwhile,the metal cations(Mg2+ and Zr4+) were incorporated into the porous Ta3N5 to enhance the PEC performance.The porous Mg/Zr co-doped Ta3N5 photoanode yielded a photocurrent density of 1.40 mA cm^(-2) at 1.23 V vs RHE,which is 5.6 times higher than that of the dense Ta3N5 photoanode.The enhanced performance should be ascribed to the synergistic effect of porous structure and cation doping,which can enlarge the electrochemical active surface area and accelerate the charge transfer by introducing ON substitution defects.Subsequently,Co(OH)2 cocatalyst was loaded on the Mg/Zr-Ta3N5 photoanode to negatively shift the onset potential to 0.45 V vs RHE and further improve the photocurrent density to 3.5 mA cm^(-2)at 1.23 V vs.RHE,with a maximum half-cell solar to hydrogen efficiency of 0.45%.The present study provides a new strategy to design efficient Ta3N5 photoelectrodes via the simultaneous control of the morphology and composition.

Short-term effects of fire disturbance on CH4 emission from forested wetlands in the Xiaoxing’an Mountains, Northeast China

Using static chamber gas chromatography, we determined the seasonal dynamics, controlling factors, and distribution patterns of forest swamp CH4 levels and related environmental factors (temperature, water level) after fire disturbance in the Xiaoxing’an Mountains. The results showed the following: during the growing season, the annual CH4 emission distribution ranged from - 0.001 ± 0.012 to 22.373 ± 3.650 mg m^-2 h^-1;mild fire caused the swamp CH4 emission flux of tussock, shrub, Alnus sibirica and birch swamp to increase by 56.0–524.7%;at low water levels, temperature had a significant influence on the swamp type, and the correlation between the methane emission flux and temperature was significantly strengthened;after a fire disturbance, methane emissions from all types of marsh were highest in summer and second highest in autumn, with a weak absorption in spring;and along the water environment gradient of the transition zone, the CH4 emission flux presented a decreasing trend in its spatial distribution pattern.

Analysis of Concrete Crack Treatment Technologies in Buildings

With the continuous development of civil engineering,concrete crack treatment technology has become an important research field.This paper proposes treatment techniques for different types of cracks,including the prevention and repair of surface cracks,the reinforcement and grouting of structural cracks,and the design and construction of controlled cracks through the analysis of the causes and classification of concrete cracks.The methods and suggestions proposed in this paper are practical and can improve the quality and safety of buildings.

Effects of childhood trauma on aggressive behaviors andhippocampal function:the modulation of COMT haplotypes

Background:Aggression is a commonly hostile behavior linked to the hippocampal activity.Childhood trauma(CT)exposure has been associated with altered sensitization of the hypothalamic-pituitary-adrenal(HPA)axis and hippocampal volumewhich could increase violent aggressive behaviors.Additionally,Catechol-O-methyltransferase(COMT),the major dopamine metabolism enzyme,is impli-cated in stress responsivity,including aggression.Hence,CT exposure may affect aggression through the effect on the hippocampal function,which might also be modulated by the COMT variations.Objectives:This study examined whether both CT and haplotypes of COMT moderate hippocampal function and thus affect human aggressive behavior.Methods:We obtained bilateral hippocampal functional connectivity maps using resting state functional magnetic resonance imag-ing(MRI)data.COMT haplotype estimation was performed using Haploview 4.2 and PHASE 2.1.Then we constructed a moderated mediation model to study the effect of the CTQ×COMT on aggressive behavior.Results:Three major haplotypes were generated from thirteen single nucleotide polymorphisms(SNPs)within the COMT gene and formed three haplotypes corresponding to high,medium,and low enzymatic activity of COMT.The results showed interactive re-lationships between the Childhood Trauma Questionnaire(CTQ)and COMT with respect to the functional connectivity(FC)of the bilateral hippocampus(HIP)-orbital frontal cortex(OFC).Specifically,CT experience predicted lower negative HIP-OFC coupling in the APS and HPS haplotypes corresponding to the medium and high enzymatic activity of COMT,but greater FC in the LPS haplotypes corresponding to the low enzymatic activity.We also observed a conditional mediation effect of the right HIP-OFC coupling in the link between COMT and aggressive behavior that was moderated by CT experience.Conclusions:These results suggest that CT and COMT have a combined effect on aggressive behavior through hippocampal function.This mediation analysis sheds light on the influence of childhood experience on aggressive behavior in different genetic backgrounds.