Synergistic effects of low-dose arsenic and N-methyl-N'-nitro-N-nitrosoguanidine co-exposure by altering gut microbiota and intestinal metabolic profile in rats.

Biological organisms are exposed to low-dose arsenic or N-nitro compounds (NOCs) alone or in combination worldwide, especially in areas with high cancer prevalence through drinking water or food exposure; however, information on their combined exposure effects is limited. Here, we conducted an in-depth study of the effects on the gut microbiota, metabolomics, and signaling pathways using rat models exposed to arsenic or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), one of the most active carcinogenic NOCs, separately or in combination with metabolomics and high-throughput sequencing. Compared to exposure alone, combined exposure to arsenic and MNNG exacerbated damage to gastric tissue morphology, interfered with intestinal microflora and substance metabolism, and exerted a stronger carcinogenic effect. This may be related to intestinal microbiota disorders, including Dyella, Oscillibacter, Myroides, and metabolic pathways such as glycine, serine, and threonine metabolism, arginine biosynthesis, central carbon metabolism in cancer, and purine and pyrimidine metabolism, thereby enhancing the cancer-causing effects of gonadotrophin-releasing hormone (GnRH), P53, and Wnt signaling pathways.

Tribological behaviors of laser textured surface under different lubrication conditions for rotary compressor.

Tribological behaviors of laser textured surface with elliptical dimples were experimentally compared with that of the smooth one under different lubrication conditions, including the poor-oil, rich-oil and dry lubrication. The lubrication regime was analyzed with the increasing operating load by ring-on-ring tribological tests. Finally, the performance impact of rolling piston rotary compressor with textures fabricated on the thrust surfaces was investigated. Results show that the tribological improvement strongly depends on lubrication condition. With the increase of applied loads under rich-oil and poor-oil lubrication, the effect of micro dimple promotes the critical load transforming lubrication regime, and expands the range of hydrodynamic lubrication, meanwhile maintains a similar minimum of friction coefficient as the smooth surface but enhances wear resistance. However, it is reverse to increase the friction coefficient and surface wear for the textured surfaces under dry lubrication. The compressor performance can be improved significantly by laser surface texturing with a 2% reduction of friction power consumption and a 2.5% enhancement of energy efficiency ratio.

Simultaneous saccharification and fermentation of cassava to succinic acid by Escherichia coli NZN111.

In this study, the production of succinic acid from cassava starch and raw cassava instead of glucose by Escherichia coli NZN111 was investigated. During the two-stage fermentation, simultaneous saccharification and fermentation (SSF) was applied in the anaerobic stage. The results showed that both the productivity and specific productivity in the process conducted at 40°C were higher than those in the cultivation conducted at 37°C. The yield of succinic acid based on the amount of added starch reached the highest level 0.86 g/g and cassava starch was almost totally hydrolyzed in the SSF process. With the improved cell density, 127.13 g/L of succinic acid was obtained. When the liquefied crude cassava powder was used directly in SSF, 106.17 g/L of succinic acid was formed. The result showed that crude cassava powder could be another cheap raw material for succinic acid formation.