Interfacial distribution and compatibilization of imidazolium functionalized CNTs in poly(lactic acid)/polycaprolactone composites with excellent EMI shielding and mechanical properties.

Imidazolium-functionalized polyurethane (IPU) functionalized multi-walled carbon nanotubes (CNTs) was used to control interfacial distribution and compatibilization of CNTs, and enhance electromagnetic interference (EMI) shielding and mechanical properties of poly(lactic acid)/polycaprolactone (PLA/PCL) based composites. IPU facilitated the uniformly dispersion of CNTs and induced the selectively location of CNTs at the interface and PCL phase, which is beneficial to build more effective three-dimensional network structure at the co-continuous interphase. The EMI shielding properties for the PLA/PCL/8CNT/0.8IPU composites have been evidently increased to 35.6 dB. Meanwhile, the elongation at break and the notched impact strength of the PLA/PCL/8CNT/0.8IPU composite reached 307.8 % and 51.3 kJ/m2, respectively, which are increased by 27 and 53 % of PLA/PCL/8CNT because of the compatibilization effect of IPU and the distribution of CNTs. This work presented a promising prospect of polymer-based composites with satisfactory EMI shielding and mechanical properties.

Residual thickness enhanced core-removed D-shaped single-mode fiber and its application for VOC evaporation monitoring.

A core-removed D-shaped structure with different residual thickness (RT) was manufactured on a single mode silica fiber (SMF) to enhance the sensitivity by using of ultra-precise polishing technology. With six different RTs ranging from ∼55 µm to ∼28 µm, the RT enhancement effect in a D-shaped SMF was researched in detail. The influence of the RT on its transmission spectra was investigated both theoretically and experimentally. Considering a compromise between the multimode interference efficiency and optical power loss, an optimum RT value of 34.09 µm was achieved. The obtained refractive index (RI) sensitivity was 10243 nm/RIU in the RI range of 1.430-1.444, corresponding to a RI resolution of 1.9×10-6 RIU. A high-performance all-fiber sensor was developed to monitor the evaporation process volatile organic compounds (VOCs) based on the RT-enhanced D-shaped SMF. As proof of concept, a 2-hour continuous monitoring was carried to monitor the chloroform and alcohol mixture. As a result, the evaporation of alcohol and chloroform were clearly identified and monitored. The developed RT-enhanced D-shaped fiber sensor provides an alternative way for chemical process monitoring and industrial applications.

Quartz-enhanced photoacoustic spectroscopy employing pilot line manufactured custom tuning forks.

Pilot line manufactured custom quartz tuning forks (QTFs) with a resonance frequency of 28 kHz and a Q value of >30, 000 in a vacuum and ∼ 7500 in the air, were designed and produced for trace gas sensing based on quartz enhanced photoacoustic spectroscopy (QEPAS). The pilot line was able to produce hundreds of low-frequency custom QTFs with small frequency shift < 10 ppm, benefiting the detecting of molecules with slow vibrational-translational (V-T) relaxation rates. An Au film with a thickness of 600 nm were deposited on both sides of QTF to enhance the piezoelectric charge collection efficiency and reduce the environmental electromagnetic noise. The laser focus position and modulation depth were optimized. With an integration time of 84 s, a normalized noise equivalent absorption (NNEA) coefficient of 1.7 × 10-8 cm-1∙W∙Hz-1/2 was achieved which is ∼10 times higher than a commercially available QTF with a resonance frequency of 32 kHz.

Influence of Tuning Fork Resonance Properties on Quartz-Enhanced Photoacoustic Spectroscopy Performance.

A detailed investigation of the influence of quartz tuning forks (QTFs) resonance properties on the performance of quartz-enhanced photoacoustic spectroscopy (QEPAS) exploiting QTFs as acousto-electric transducers is reported. The performance of two commercial QTFs with the same resonance frequency (32.7 KHz) but different geometries and two custom QTFs with lower resonance frequencies (2.9 KHz and 7.2 KHz) were compared and discussed. The results demonstrated that the fundamental resonance frequency as well as the quality factor and the electrical resistance were strongly inter-dependent on the QTF prongs geometry. Even if the resonance frequency was reduced, the quality factor must be kept as high as possible and the electrical resistance as low as possible in order to guarantee high QEPAS performance.

[Studies of somatic embryogenesis and genetic transformation by Agrobacterium- mediated in soybean].

Somatic embryogenesis was induced and the regenerated plants were obtained by higher concentrations of auxins with immature cotyledon of 55 genotypes in soybean. Bivalent insect resistant genes were transformed into immature cotyledon of soybean which have high frequency of somatic embryogenesis via Agrobacterium-mediated. The results showed that 14 genotypes possessed high frequency of somatic embryogenesis (more than 40%) among soybean genotypes from Northeast area. 2147 immature cotyledons of 5 different soybean genotypes cultured in Northeast area were inoculated with LBA4404 (including pGBI121S4ABC plasmid). 17 plantlets were obtained under Kanamicy selection. 12 plantlets showed positive reaction in PCTR and PCR-Southern detection. These analyses confirmed the presence of introduced Bt gene in soybean.