Validity Study on the Test Paper of the Academic English Reading and Writing Course

The aim of this study is to conduct the validity analysis of the test paper of the academic English reading and writing course referring to the freshmen of non-English majors in a university of Technology in Shanghai.The validity is mainly analyzed from these three aspects:the content and construct validity,the reaction process,and the internal structure of the test paper.And the principles of language assessment in the design of the test paper are given in this study.The validity study was also conducted in a class with 42 freshmen,and the scores of them were analyzed through the internal correlation coefficient from Statistic Package for Social Science(SPSS)25.0.Finally,the validity of the test paper is concluded.

Silicon quantum dots-based fluorescent sensor for the detection of cobalt with high sensitivity and selectivity

Fluorescent silicon quantum dots(Si QDs)were hydrothermally synthesized from a mixture of 3(2-aminoethylamino)propyl(dimethoxymethylsilane)(AEAPDMMS)and poly(vinylpyrrolidine)(PVP).The resulting Si QDs exhibited good water solubility and high stability.Under the optimized conditions,the probe revealed an excellent linear fluorescence quenching effect on Co2+ranging from 1μmol/L to 120μmol/L with a limit of detection of 0.37μmol/L(based on 3 s/k).The quenching mechanism was studied,showing that static quenching(SQE)causes the main effect.Furthermore,the test paper based on Si QDs was prepared,which is cost-effective,high sensitivity,good selectivity,easy to use and show excellent anti-interference capability.This method was applied to analyze the content of Co2+in environmental water samples with satisfying results.

3DRGO-NiFe2O4/NiO nanoparticles for fast and simple detection of organophosphorus pesticides

The residues of organophosphorus pesticide(OPs)on fruits and vegetables pose a threat to human health,so it is very meaningful to explore simple and fast detect methods for OPs residual.In this work,nickel ferrite/nickel oxide nanoparticles co-loaded three-dimensional reduced graphene oxide(3DRGONiFe2O4/NiO NPs),as a new low cost nanocomposite,was prepared.Based on its high performance mimetic peroxidase activity,a colorimetric method for the detection of OPs has been developed.Dichlorvos was chosen as model compounds to evaluate the detection performance.The detection linear range for dichlorvos is from 50μg/mL to 2.5×10^4μg/mL with a detection limit of 10μg/mL.Furthermore,a test paper can be developed based on the 3 DRGO-NiFe2O4/NiO NPs for visual detection of dichlorvos,and the image information of the paper sensor can be converted into digital signal and quantitative detection by a smartphone.Notably,this method can also be used to detect dichlorvos in real samples,including vegetables and fruits.Thus,the developed naked assay holds great potential in simple,inexpensive and rapid detection of OPs in fruit and vegetable samples.

Portable device for on-site detection of ammonia nitrogen

Portable measurement of ammonia nitrogen in water is of great significance for water qual-ity monitoring.It’s beneficial to reduce biological diseases and promote aquatic product safety.Traditional methods such as Nessler’s reagent method suffer from complex opera-tion,time delays and toxic residues.To realize simple and pollution-free detection,this paper develops a low-cost portable device for ammonia nitrogen detection.A test paper was proposed to cooperate the device and offer a chromogenic reaction.The portable device reduces the impact of any ambient light,simplifies the operation,and provides human–computer interaction.The result obtained for the detection range of 0.4–10 mg/L(R^(2) are 0.9902 and 0.9893 for the rang of 0.4–4.5 and 4.5–10 mg/L,respectively)with the detection limit of 0.36 mg/L,and the average recovery of aquaculture water is 100.98–137.75%.The results show that the portable device can provide a great potential for on-site detection ammonia nitrogen concentration.