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Microfluidic approaches for the determination of interfacial tension and viscosity of liquid-liquid systems still face some challenges. One of them is liquid-liquid systems with low interfacial and high viscosity, because dripping flow in normal microdevices can’t be easily realized for the systems. In this work, we designed a capillary embedded step T-junction microdevice to develop a modified microfluidic approach to determine the interfacial tension of several systems, specially, for the systems with low interfacial tension and high viscosity. This method combines a classical T-junction geometry with a step to strengthen the shear force further to form monodispersed w/o or Aqueous Two-phase (ATP) droplet under dripping flow. For systems with low interfacial tension and high viscosity, the operating range for dripping flow is relative narrow whereas a wider dripping flow operating range can be realized in this step T-junction microdevice when the capillary number of the continuous phase is in the range of 0.01 to 0.7. Additionally, the viscosity of the continuous phase was also measured in the same microdevice. Several different systems with an interfacial tension from 1.0 to 8.0 mN·m−1 and a viscosity from 0.9 to 10 mPa·s were measured accurately. The experimental results are in good agreement with the data obtained from a commercial interfacial tensiometer and a spinning digital viscometer. This work could extend the application of microfluidic flows.

Doubled haploid breeding (DH breeding) is one of the major maize breeding techniques. The screening of haploid seeds is an essential link of DH breeding. Oil marking method is more stable than other haploid marking methods, which makes the oil content of haploid and diploid seeds significantly different. Currently, it is the most mature way to measure the oil content of maize seeds by nuclear magnetic resonance (NMR) spectrometer. However, the slow speed, high cost, and large volume have restricted the wide applications of NMR spectrometer. Similar to NMR, near infrared spectroscopy (NIRS) can also be used for the non-destructive screening of seeds. Moreover, compared with NMR spectrometer, NIRS spectrometer has a fast speed, low cost, and small volume. This study attempts to explore a maize haploid seed screening solution based on NIRS quantitative analysis to meet the demand of large-scale DH breeding. In this study, a screening solution for Maize Haploid seeds based on the quantitative analysis of NIRS is proposed, and tests of the solution by two representative varieties show a consistent average accuracy above 90%. A model monitoring and calibration solution based on small sample set is proposed to guarantee the stability and efficiency of the screening solution. The reason for the poor separability of the non-embryo side diffuse reflectance spectra is analyzed, and the feasibility of the non-embryo side spectra is verified by analyzing the spectral information of hyperspectral data. In summary, this research provides a more economical and efficient solution for maize haploid screening.

The kinetics of p-nitrotoluene nitration with mixed acid is important to industrial process design and safety control. However, it's difficult to acquire accurate kinetic data and no kinetics study has ever been reported before because of fast, highly exothermic and heterogeneous characteristics. In this work, a continuous-flow microreactor system including a micromixer, a capillary reactor and an online quenching module was designed to carry out the nitration under a homogeneous reaction condition. The homogeneous nitration can completely eliminate mass transfer resistance between phases, and accurately control reaction temperature and residence time in the continuous-flow microreactor system. The observed reaction rate constants separately based on HNO3 and NO2+, pre-exponential factor and activation energy of p-nitrotoluene nitration were obtained and a general method was established to collect kinetics data for such a kind of fast and highly exothermal nitration reactions.