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BackgroundPrinters can release particles, which is harmful to human health. However, there is insufficient research on how printing conditions affect the level of particles released by printers.ObjectiveTo explore the effects of different printing conditions on the level of printer-emitted particles.MethodsThe experiment was carried out in a closed experimental chamber, and the changes in the number concentration of particles (size range: 0.25-32 μm) and ozone concentration in the experimental chamber during designed printing process were monitored with a portable aerosol particle size spectrometer and an ozone detector respectively. The monitoring included three parts: 2 min before printing as the background number concentration, printing 72 sheets with a designed printing task sets, and then 10 min after printing. A set of printing tasks with predetermined conditions included font, font size, single/double-sided printing mode, page layout, paper size, paper brand, and paper moisture content. The association between printing conditions and level of printer-emitted particles was evaluated by Spearman correlation analysis.ResultsWhen printing in different fonts (Song and Kai) and different font sizes (14 points and 10.5 points), the number concentration peaks of particles in the experimental chamber were 14.71-59.35 P·cm−3, and there was no significant difference (P>0.05). There was no difference in the peak concentrations of printer-emitted particles between single-sided printing and double-sided printing (P>0.05), but there was a significant difference in the time of peak occurrence (P middle 1/ 3> lower 1/3). No increase in the concentration of printer-emitted particles was detected when printing with B5 paper. The peak concentration of printer-emitted particles in printing paper with varying degrees of paper moisture showed differences (P0.05).ConclusionBy changing printing conditions, the levels of printer-emitted particles are affected. Among them, page layout, paper size, and degree of paper moisture have a significant impact on the results; however, single/double-sided printing, font, font size, and paper brand have no significant impact on the results.

In order to enhance the flavor of hydrolysate from the mixture of chicken skeleton and chicken breast, the hydrolysis of chicken skeleton and chicken breast composite substrate was carried out by biological enzymatic hydrolysis technology. The enzymatic hydrolysis process was optimized by single factor experiment and orthogonal experiment. Furthermore, the free amino acid content and molecular weight distribution of peptide in hydrolysates were analyzed. The results pointed out that the flavor of hydrolysate was better using simultaneous hydrolysis with protamex and flavourzyme by the ratio of 3:1. The optimal enzymolysis conditions were as follows: Ratio of chicken skeleton to chicken breast 9:1, solid-liquid ratio 1:2 g/mL, temperature 50 ℃, pH7.5, enzyme dosage 0.6%, and hydrolysis time 3 h. Under these conditions, the hydrolysate had a prominent umami taste, obvious meat flavor and good taste, with hydrolysis degree and sensory score of 13.60% and 4.7, respectively. With the prolongation of enzymatic hydrolysis time, the content of total free amino acids and peptides with low molecular weight increased continuously. Under the optimal process conditions, the content of bitter amino acids in the hydrolysate was 2.74 mg/mL, accounting for 71.73% of the total free amino acids, which were the main amino acids, and the content of peptides with molecular weight less than 3 kDa was 93.26%. The results provide a reference for the comprehensive development and application of low-value chicken skeleton.

Disturbances of gut microbiota may affect the balance of the host immune system. The metabolism of gut microbiota produces many bioactive molecules interacting with host, typically secondary bile acids (SBAs). SBAs are involved in regulating the energy metabolism and the expression of inflammatory response-related genes by binding to membrane receptors and nuclear receptors, such as takeda G protein-coupled receptor (TGR5) and farnesol X receptor (FXR), which are essential for maintaining host immune homeostasis.