The outstanding overall performance of polyimide (PI) films is critical for their application in the microelectronic and optoelectronic industries. A series of novel PI films containing trifluoromethoxy groups were prepared from a 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)/2,2′-bis (trifluoromethyl) biphenyl-4,4′-diamine (TFMB)/2,2′-bistrifluoromethoxy-biphenyl-4,4′-diamine (TFMOB) tri-copolymer in this paper. The comprehensive performances of the derived PI films could be modulated by the molar ratio of TFMOB/TFMB, and each performance of the PI films was explored in detail. All PI films exhibited excellent overall performance against PI-ref (PI films were prepared by PMDA and ODA in our lab, which referred to the raw materials of Kapton films), especially PI-30, which possessed the best performance, such as remarkable thermal stability (T 5% = 581 °C and T g = 368 °C), outstanding mechanical properties (T S = 195 MPa and T M = 3.5 GPa), ultralow moisture absorption (M a = 0.74%), lower dielectricity (D k = 2.877 and D f = 0.00815 at 10 GHz), and high optical transparency. In addition, PI-50 had the largest breaking elongation (E b = 27.6%), PI-70 had the lowest dielectric loss (D f = 0.00514), and PI-100 presented the lowest moisture absorption (M a = 0.50%). Each PI film possessed its own unique advantages to meet the special demand. Subsequently, the PI-30 film was used as a colorless and transparent substrate for flexible circuits, which could withstand multiple bends and still maintained excellent electrical performance after 1,40,000 folding times. The high comprehensive performance makes these PI films favorable candidates for flexible circuit substrates, foldable screens, and solar panels in the optoelectronic engineering and microelectronics industries.

Bifidobacteria-loaded alginate poly-l-lysine microparticles (bap microparticles) were prepared using an air atomization method and then freeze-dried. The viability of the bap microparticles was investigated as a function of the amount of the bifidobacteria cultures, and the addition of a yeast extract, cryoprotectants, antioxidants and neutralizer. The size of the bap microparticles with and without the bifidobacteria was 84.8 +/- 28.5 microm (mean +/- standard deviation) and 113.1 +/- 38.5 microm, respectively. The surface morphology was slightly ellipsoid and wrinkled regardless of the incorporating bifidobacteria. The viability gradually decreased with increasing freeze-drying time. Free-flowing powdered bap microparticles were obtained at least 12 h after freeze-drying the wetted slurry of bap microparticles. However, the particles tended to aggregate when either lactose or ascorbic acid was added. The addition of a yeast extract, cryoprotectants (glycerol and lactose), antioxidants (NaHSO3 and ascorbic acid) and neutralizer (Mg3(PO4)2) resulted in a significantly higher viability of the bifidobacteria in the bap microparticles after freeze-drying (0.34-1.84 log) compared with the culture alone.

No abstract

No abstract

UV/H 2 O 2 /micro-aeration is a newly developed process based on UV/H 2 O 2 . Halogenated pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) photochemical degradation in aqueous solution was studiedunder various solution conditions. The UV intensity, initial 2,4-D concentrations and solution temperature varied from 183.6 to 1048.7 μW·cm −2 , from 59.2 to 300.0 μg·L −1 and from 15 to 30℃, respectively. The concentration of hydrogen peroxide (H 2 O 2 ) and pH ranged from 0 to 50 mg·L −1 and 5 to 9, and different water quality solutions (tap water, distilled water and deionized water) were examined in this study. With initial concentration of about 100 μg·L −1 , more than 95.6% of 2,4-D can be removed in 90 min at intensity of UV radiation of 843.9 μW·cm −2 , H 2 O 2 dosage of 20 mg·L −1 , pH 7 and room temperature. The removal efficiency of 2,4-D by UV/H 2 O 2 /micro-aeration process is better than UV/H 2 O 2 process. The photodecomposition of 2,4-D in aqueous solution follows pseudo-first-order kinetics. 2,4-D is greatly affected by UV irradation intensity, H 2 O 2 dosage, initial 2,4-D concentration and water quality solutions, but it appears to be slightly influenced by pH and temperature. There is a linear relationship between rate constant k and UV intensity and initial H 2 O 2 concentration, which indicates that higher removal capacity can be achieved by the improvement of these factors. Finally, a preliminary cost analysis reveals that UV/H 2 O 2 /micro-aeration process is more cost-effective than the UV/H 2 O 2 process in the removal of 2,4-D from drinking water.