Smart Technology for “Clean Your Plate” Campaign against Wasting Food in University Canteens

Food security is becoming increasingly prominent due to the impact of the COVID-19 and extreme weathers. The Smart Project for “Clean Your Plate” Campaign has been designed and implemented to address food waste on campus. The project takes advantage of technologies such as IoT, dynamic QR code, and visual recognition. Smart devices for clear plate recognition can be installed in multiple locations in campus cafeterias and canteens. Users can login onto a public account and a Mini Program for points reward, exchange and sale. Combining offline clear plate recognition and online points exchange, the project encourages food saving and reduces human cost for university canteens.

Surface Water Quality Assessment Using Multivariate Statistical Techniques:Case Study of Songhua River Basin,China

Multivariate statistical techniques,such as principal component analysis(PCA),factor analysis(FA)and cluster analysis(CA),were applied to evaluating and interpreting the surface water quality datasets of the Songhua River Basin(SRB)in China,obtained during two years(2012-2013)of monitoring of 13 physicochemical parameters at 29 different sites.PCA assisted to recognize the factors or origins responsible for surface water quality variations and identified three latent factors and explained 83.79%of the total variance,standing for organic pollution,metal pollution and oil pollution,respectively.FA revealed that the SRB water chemistry was strongly affected by the discharge of industrial,agricultural and municipal sewage water,mining operations and petroleum exploitation.Hierarchical CA grouped 29 different sampling sites into three groups,i.e.,relatively less polluted(LP),moderately polluted(MP)and highly polluted(HP)sites,based on the similarity of water quality characteristics.This study illustrates the usefulness of multivariate statistical techniques for the analysis and interpretation of huge and complex data sets,identification of pollution sources and better understanding variations in water quality for effective surface water management.

Grey Relevance Analysis of Major Factors of Energy-Related CO2 Emissions in Tianjin,China

Energy-related CO2 emissions from Tianjin’s production and household sectors during 2000–2012 were calculated based on the default carbon-emission coefficients provided by the Intergovernmental Panel on Climate Change.Grey relational analysis was used in this study to capture the dynamic characteristics of 12 different factors related to CO2 emissions.The results indicated that population scale and structure,industrial structure,per capita disposable income,energy consumption and structure appeared as the main drivers related to the CO2 emissions increase during the study period.Based on the research,we make the policy recommendations including optimizing the industrial structure and energy structure,improving energy efficiency and promoting low-carbon consumption.

H-bonding interactions enable a 3D pillared cobalt(Ⅱ) coordination polymer for touchless finger moisture detection

Coordination polymers(CPs) are emerging as the next generation of macromolecule materials in many industrial and technological applications,e.g.gas/humidity sensing.The design of CP-based sensors with high performance and low cost is of significance,but this work is still in the infancy stage.In this contribution,a new one dimensional(1D) CP has been successfully synthesized by a simple solvent evaporation method at room temperature,namely [Co(DPP)(H_(2)O)_(2)]n·(TCA)2(H_(2)O)_(4)(named as Co-1,HTCA=3-thiophenezoic acid,DPP=1,3-di(4-pyridyl)propane).The Co-1 structure contains abundant H-bonding interactions,weaving it from 1D chain structure into three dimensional(3D) pillared-layer structure.As an impedimetric humidity sensing material,this CP exhibits short response time,small hysteresis,excellent repeatability,and good stability in the working range of 11%-97% relative humidity(RH).Furthermore,it also shows excellent performance in monitoring the moisture content of human finger skin.By analyzing the complex impedance spectra,the humidity sensing mechanism of Co-1 sensor was expounded at different RH ranges.

Toxicological effects of rare earth yttrium on wheat seedlings(Triticum aestivum)

This study examined the biochemical responses of wheat（Triticum aestivum） to the stress of rare earth yttrium（Y） and showed that 25–100 mg/kg Y treatments evidently increased the biomass（root mass,shoot mass and leaf mass）,accompanied by a significant（p0.05） increase in the chlorophyll（CHL） content in wheat leaves.Increased malondialdehyde（MDA） levels were detected in wheat shoots（stem and leaf） and roots too,indicating the presence of poisoning active oxygen species（AOS）.The MDA content in wheat roots increased with the augmentation of Y concentration.These results indicated that there was a dose-dependent effect of Y on the changes of MDA content in wheat roots.Although the activities of superoxide dismutases（SOD）,peroxidases（POD） and catalases（CAT） in wheat shoots and roots irregularly fluctuated with the increase in Y concentration,25–100 mg/kg Y significantly（p0.01） increased the activities of SOD and POD.In general,the dose-dependent effects of Y on the activity of antioxidant enzymes were insignificant.Our data also indicated that the increase in SOD and POD activities could be used as a good biomarker for the stress induced by low concentrations of Y.

Rich defects and nanograins boosted formaldehyde sensing performance of mesoporous polycrystalline ZnO nanosheets

Comprehensive consideration of structural and electronic sensitization is of significant importance for rational design and assembly of high-performance gas sensors based on metal oxides.In this work,hierarchically mesoporous ZnO nanosheets are synthesized via a hydrothermal method followed by calcination.Material characterization reveals polycrystalline feature of these ZnO nanosheets rich in mesopores and defects.Gas sensing performance of as-synthesized ZnO nanosheets was sys-tematically investigated,taking formaldehyde as probe molecules.Compared with commercial ZnO nanoparticles,ZnO nanosheets exhibited enhanced formaldehyde sensing properties,including lower operation temperature,higher sensitivity,faster response,and smaller detection limit.Notably,the response(S=227.4)of ZnO nanosheets to 200×10^(-6) formaldehyde is about 17 times larger than that of ZnO nanoparticles(S=13.5).Excluding effects of grain size and surface area,enhanced sensing properties,especially response value,are credited in large part to synergistic actions of surface defects,grain boundaries,as well as unique structural advantage of ZnO nanosheets.Furthermore,this work offers a guideline for boosting performance of metal oxide-based gas sensors via surface defect control and grain boundary construction.

A highly efficient humidity sensor based on lead(Ⅱ) coordination polymer via in-situ decarboxylation and hydrolysis synthesis

Function-oriented design of coordination polymers is emerging as an attracting topic to explore their practical applications, e.g., gas/humidity sensing. However,the successful synthesis of new coordination polymers showing splendid sensing property is an urgent need in fields of materials and sensors, yet still at the initial stage.In this contribution, a new one-dimensional(1D) coordination polymer with formula of [Pb(TAA)(BA)(H_(2)O)]_(n)(namedasPbL,HTAA = 3-thiopheneaceticacid,HBA = benzoic acid) has been successfully synthesized by a hydrothermal method, which involves in-situ synthesis of both decarboxylation and hydrolysis. As an impedimetric humidity sensing material, this coordination polymer exhibits excellent humidity sensing performance including high response, fast response, small hysteresis, and good repeatability. In the total relative humidity range(11%–97%) at room temperature, it is worth noting that the sensitivity of the humidity sensor is as high as 1.18×10^(4),the response time is only 2 s, and the max humidity hysteresis is as small as 1.8%. At last, we discussed the sensing mechanism using the alternating current(AC) impedance technique at various relative humidity.