Fabrication and Characterization of Au Nanoparticle-aggregated Nanowires by Using Nanomeniscus-induced Colloidal Stacking Method

We fabricate and characterize Au nanoparticle-aggregated nanowires by using the nano meniscus-induced colloidal stacking method. The Au nanoparticle solution ejects with guidance of nanopipette/quartz tuning fork-based atomic force microscope in ambient conditions, and the stacking particles form Au nanoparticle-aggregated nanowire while the nozzle retracts from the surface. Their mechanical properties with relatively low elastic modulus are in situ investigated by using the same apparatus.

Evaluation of Dynamic Changes of IgG and IgM in COVID-19 Patients by Different Detection Methods

Objective: To analyze the dynamic evaluation of chemiluminescence, colloidal gold, and immunofluorescence chromatography in detecting antibodies in COVID-19 patients within four weeks of infection, and to provide evidence for clinical application. Method: 74 patients with confirmed SARS-COV-2 infection in the local area were selected as the experimental group, while 231 patients with negative SARS-COV-2 results but not vaccinated with Covid19 vaccine were selected as the control group;during the first, second, third, and fourth weeks after enrollment in the experimental group, three methods were used to detect SARS-COV-2 IgG and IgM in patients’ blood: chemiluminescence method, colloidal gold antibody method, and immuno-fluorescence chromatography. In the control group, three methods were used to detect SARS-COV-2 IgG and IgM during physical examination for SARS-COV-2 nucleic acids. The ROC curve was drawn to analyze the value of each indicator in predicting SARS-COV-2 infection, and the kappa method was used to analyze the consistency of the detection results of each indicator. Results: There was no significant difference in the positive rates of SARS-COV-2 IgM and IgG antibodies detected by chemiluminescence, colloidal gold, and immunofluorescence chromatography during the four-week period (P > 0.05). The positive rates of SARS-COV-2 IgM and IgG antibodies detected by the three methods during the first week of infection were not higher than 60%;when the three methods were used to detect SARS-COV-2 IgM and IgG in vivo, the AUC diagnosed by the test results was less than 0.80 at the first week, the diagnostic efficacy of the three methods was above 0.95 from the second week to the fourth week, and the diagnostic efficacy of the three methods was higher than 0.97 at the fourth week. The diagnostic efficacy of the three methods was comparable;the three methods for detecting SARS-COV-2 IgM and IgG antibodies showed high consistency in four cycles. Conclusion: Chemiluminescence, colloidal gold, and immunofluorescence chromatography are highly consistent in the detection of SARS-COV-2 IgM and IgG antibodies, and can be used as an auxiliary diagnosis and efficacy observation of novel coronavirus infections according to the needs, but the positive rate of infected people in the first week is low.

Colloidal synthesis and characterization of Cu_2ZnSnS_4 nanoplates

Synthesis of copper zinc tin sulphide（Cu_2ZnSnS_4/ with nanoplate morphology was achieved through colloidal method using oleic acid as capping agent and solvent with 1-octadecene（1-ODE） at 240°C.X-ray diffraction（XRD） analysis shows that the synthesized nanoplates possessed pure kesterite phase.SEM analysis clearly shows the formation of nanoplates having the size of about 50–100 nm.Electron spin resonance（ESR） spectrum analysis of the prepared nanoplates shows that the valence state of copper（II） which indicates the strong coupling with other metal ions.Thermo gravimetric/differential thermal analysis（TG/DTA） analysis shows the weight loss of sample at 450°C predicting the loss of capping ligands on the surface of the nanoparticles.The possible mechanism for the conversion of nanoplate-like structures during synthesis was discussed.The results are discussed in detail.

Using the DEM-CFD method to predict Brownian particle deposition in a constricted tube

Modelling of the agglomeration and deposition on a constricted tube collector of colloidal size particles immersed in a liquid is investigated using the discrete element method （DEM）. The ability of this method to represent surface interactions allows the simulation of agglomeration and deposition at the particle scale. The numerical model adopts a mechanistic approach to represent the forces involved in colloidal suspensions by including near-wall drag retardation, surface interaction and Brownian forces. The model is implemented using the commercially available DEM package EDEM 2.3~, so that results can be repli- cated in a standard and user-friendly framework. The effects of various particle-to-collector size ratios, inlet fluid flow-rates and particle concentrations are examined and it is found that deposition efficiency is strongly dependent on the inter-relation of these parameters. Particle deposition and re-suspension mechanisms have been identified and analyzed thanks to EDEM＇s post processing capability. One-way coupling with computational fluid dynamics （CFD） is considered and results are compared with a two- way coupling between EDEM 2.3 and FLUENT 12.1. It is found that two-way coupling requires circa 500% more time than one-way coupling for similar results.

Synthesis-temperature-dependent phase composition manipulation toward high thermoelectric performance in tetrahedrites

Tetrahedrite,an Earth-abundant natural mineral,has attracted extensive research interest because of its excellent thermoelectric performance.Herein,tetrahedrite samples comprising Cu-poor Cu_(12)Sb_(4)S_(13)and Cu-rich Cu_(14)Sb_(4)S_(13)phases have been synthesized using a colloidal method,in which the ratio of two phases is manipulated by controlling the synthesis temperature to improve the thermoelectric perfor-mance.It is found that an ultralow total thermal conductivity of∼0.3 W m^(−1)K^(−1)at 723 K is realized in the sample with a Cu-rich phase fraction of∼50%,which can be attributed to maximized phonon scattering by phase boundaries.As a result,combined with a decent power factor,this sample obtains an optimal zT of 1.15,which is about 85%higher than that of the sample with a Cu-rich phase fraction of∼64%and comparable to zT values of other eco-friendly,abundant Cu-based thermoelectric materials.This work demonstrates an effective synthesis-temperature-dependent phase composition manipulation strategy toward enhanced thermoelectric performance in tetrahedrites.