The resistance of wood-fiber paper to water, grease, and water vapor is usually attained by immersing the base paper in hydrophobic oil, laminating with a plastic or metal film, or the application of a barrier coating...The resistance of wood-fiber paper to water, grease, and water vapor is usually attained by immersing the base paper in hydrophobic oil, laminating with a plastic or metal film, or the application of a barrier coating. Oil impregnation and the addition of films may make the paper difficult to recycle or persistent in the environment owing to their strong binding force and nondegradability. Environmental concerns have attracted worldwide attention to eco-friendly barrier coatings. In this study, degradable polyvinyl alcohol(PVA) and kaolin clay pigment were used to prepare coatings that were applied to a base paper. By measuring the barrier properties of the coated paper, including the water absorptiveness(Cobb60 value), Hercules sizing degree, oil resistance(Kit rating), and water vapor transmission rate(WVTR), an optimal coating formulation and process were proposed. To examine the barrier mechanism of the PVA/kaolin clay coating, we characterized the coating microstructures using a scanning electron microscopy(SEM) and a mercury porosimeter. The results showed that the Cobb60 value and water vapor transmission rate of the coated paper decreased by 61.4% and 98.6%, respectively, compared with the base paper, for a pre-coating weight of 0.98 g/m^2 and a top-coating weight of about 3.23 g/m^2. Furthermore, the Hercules sizing degree rose by a factor of 337.2, while the oil resistance(Kit rating) increased from 0 to 12. The optimum drying temperature for a wet coating layer was found to be 170℃, and the optimum weight ratio of PVA to kaolin clay in the coating was determined to be 50∶50. It was assumed that the PVA/kaolin clay coating improved the smoothness of the paper considerably and decreased the pore size by filling the pores on the paper surface and forming an even film, thus enhancing the paper barrier performance. The coated paper also exhibited good repulpability.展开更多
Despite its biodegradability, adequate cohesive strength and comparatively low cost, the use of cooked starch as a paper coating binder is limited due to its high viscosity and serious negative impact on the gloss. St...Despite its biodegradability, adequate cohesive strength and comparatively low cost, the use of cooked starch as a paper coating binder is limited due to its high viscosity and serious negative impact on the gloss. Starch-based bio-latex with size in the nanometer or sub-micrometer range has been developed recently to overcome these shortcomings. In this study, ultrafine starch particle(UFSP) was prepared by mechanical milling using a DYNO mill in combination with light chemical pretreatment. Model coating colors containing different dosages of UFSP were applied to base paper and the properties of the coated papers were evaluated. The results showed that the UFSP was disc-shaped with a median particle diameter of 167 nm. Water retention capacity of the coating colors was improved considerably with the addition of UFSP, i.e., the water retention value decreased by nearly 40% when styrene-butadiene latex was replaced by UFSP at a dosage of 3 pph(per hundred parts of pigment). The high shear rate viscosities of the coating colors containing no more than 2 pph of USFP were similar to that of the control coating color at shear strain rate higher than 2000 s^(-1). The properties and performances of the coated papers were comparable to the control coated paper with single synthesized latex binder. The gloss and the print gloss of paper samples with or without USFP were 59.7% and 58.2%, 79.0% and 78.8%, respectively. Surface strength of paper samples with or without USFP were 0.96 and 0.90 m/s, respectively, while the ink absorptivity values were 34% and 33%. This study demonstrates a promising approach to obtain submicrometer sized starch for paper coating.展开更多
In this study,kiwi juice was fermented with acid-resistant and bile-resistant probiotics to screen out lactic acid bacteria that can lower cholesterol and were suitable for kiwi fermentation.A non-linear fitting equat...In this study,kiwi juice was fermented with acid-resistant and bile-resistant probiotics to screen out lactic acid bacteria that can lower cholesterol and were suitable for kiwi fermentation.A non-linear fitting equation was used to establish a kinetic model of probiotics fermenting kiwi juice(R^(2)>0.90),and then a fermented juice with special effects of lowering fat was prepared.We have studied the lipid-lowering effect of fermented fruit juice through in vivo validation experiments in mice,and determined the lipid-lowering effect of fermented fruit juice according to the mouse serum indicators and the distribution of intestinal flora.The results suggested that the juice fermented with Bifidobacterium bifidum 6169 and Lactobacillus plantarum 21805 were more effective in cholesterol degradation,and the cholesterol degradation rates were 67.57%and 64.22%,respectively.The number of viable bacteria after fermentation was significantly higher than other groups(p<0.05),and the sensory score was also higher.In addition,the serum indicators were significantly ameliorated and the number of beneficial microorganisms in the intestinal flora increased after the high-fat mice were treated with fermented kiwifruit juice.The research indicates that the fermented products have a regulatory effect on cholesterol levels in mice with hyperlipidemia.展开更多
In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliab...In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant number:51403239)
文摘The resistance of wood-fiber paper to water, grease, and water vapor is usually attained by immersing the base paper in hydrophobic oil, laminating with a plastic or metal film, or the application of a barrier coating. Oil impregnation and the addition of films may make the paper difficult to recycle or persistent in the environment owing to their strong binding force and nondegradability. Environmental concerns have attracted worldwide attention to eco-friendly barrier coatings. In this study, degradable polyvinyl alcohol(PVA) and kaolin clay pigment were used to prepare coatings that were applied to a base paper. By measuring the barrier properties of the coated paper, including the water absorptiveness(Cobb60 value), Hercules sizing degree, oil resistance(Kit rating), and water vapor transmission rate(WVTR), an optimal coating formulation and process were proposed. To examine the barrier mechanism of the PVA/kaolin clay coating, we characterized the coating microstructures using a scanning electron microscopy(SEM) and a mercury porosimeter. The results showed that the Cobb60 value and water vapor transmission rate of the coated paper decreased by 61.4% and 98.6%, respectively, compared with the base paper, for a pre-coating weight of 0.98 g/m^2 and a top-coating weight of about 3.23 g/m^2. Furthermore, the Hercules sizing degree rose by a factor of 337.2, while the oil resistance(Kit rating) increased from 0 to 12. The optimum drying temperature for a wet coating layer was found to be 170℃, and the optimum weight ratio of PVA to kaolin clay in the coating was determined to be 50∶50. It was assumed that the PVA/kaolin clay coating improved the smoothness of the paper considerably and decreased the pore size by filling the pores on the paper surface and forming an even film, thus enhancing the paper barrier performance. The coated paper also exhibited good repulpability.
基金financially supported by the National Natural Science Foundation of China(Grant No.51403239)
文摘Despite its biodegradability, adequate cohesive strength and comparatively low cost, the use of cooked starch as a paper coating binder is limited due to its high viscosity and serious negative impact on the gloss. Starch-based bio-latex with size in the nanometer or sub-micrometer range has been developed recently to overcome these shortcomings. In this study, ultrafine starch particle(UFSP) was prepared by mechanical milling using a DYNO mill in combination with light chemical pretreatment. Model coating colors containing different dosages of UFSP were applied to base paper and the properties of the coated papers were evaluated. The results showed that the UFSP was disc-shaped with a median particle diameter of 167 nm. Water retention capacity of the coating colors was improved considerably with the addition of UFSP, i.e., the water retention value decreased by nearly 40% when styrene-butadiene latex was replaced by UFSP at a dosage of 3 pph(per hundred parts of pigment). The high shear rate viscosities of the coating colors containing no more than 2 pph of USFP were similar to that of the control coating color at shear strain rate higher than 2000 s^(-1). The properties and performances of the coated papers were comparable to the control coated paper with single synthesized latex binder. The gloss and the print gloss of paper samples with or without USFP were 59.7% and 58.2%, 79.0% and 78.8%, respectively. Surface strength of paper samples with or without USFP were 0.96 and 0.90 m/s, respectively, while the ink absorptivity values were 34% and 33%. This study demonstrates a promising approach to obtain submicrometer sized starch for paper coating.
基金supported by grants from the National Key R&D Program of China(2017YFD0400702)the Key Agricultural Science and Technology project of Shaanxi Provincial,China(NYKJ-2019-XA)the Key Research and Development Plan of Shaanxi Province,China(2020NY-096).
文摘In this study,kiwi juice was fermented with acid-resistant and bile-resistant probiotics to screen out lactic acid bacteria that can lower cholesterol and were suitable for kiwi fermentation.A non-linear fitting equation was used to establish a kinetic model of probiotics fermenting kiwi juice(R^(2)>0.90),and then a fermented juice with special effects of lowering fat was prepared.We have studied the lipid-lowering effect of fermented fruit juice through in vivo validation experiments in mice,and determined the lipid-lowering effect of fermented fruit juice according to the mouse serum indicators and the distribution of intestinal flora.The results suggested that the juice fermented with Bifidobacterium bifidum 6169 and Lactobacillus plantarum 21805 were more effective in cholesterol degradation,and the cholesterol degradation rates were 67.57%and 64.22%,respectively.The number of viable bacteria after fermentation was significantly higher than other groups(p<0.05),and the sensory score was also higher.In addition,the serum indicators were significantly ameliorated and the number of beneficial microorganisms in the intestinal flora increased after the high-fat mice were treated with fermented kiwifruit juice.The research indicates that the fermented products have a regulatory effect on cholesterol levels in mice with hyperlipidemia.
基金This work was supported by the National Natural Science Foundation of China (No. 41404022) and the Shanxi National Science Foundation (No. 2015JM4128).
文摘In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.