Investigation of the deterioration of passive films in H_2S-containing solutions

The effect of H_2S on the corrosion behavior of 316 L stainless steel was investigated using electrochemical methods by changing the gas condition from CO_2 to H_2S and then back to CO_2. The presence of H_2S showed an acceleration effect on the corrosion of 316 L stainless steel in comparison with CO_2. The acceleration effect remained even after the complete removal of H_2S by CO_2, indicating that the passive film was irreversibly damaged. X-ray photoelectron spectroscopy(XPS) analysis indicated that the passive film was composed of Cr_2O_3, Fe_2O_3, and FeS_2 after being immersed in H_2S-containing solutions. The semiconducting property of the passive film was then investigated by using the Mott–Schottky approach. The presence of sulfides resulted in higher acceptor and donor densities and thus was responsible for the deterioration of passive films.

Wheat silage partially replacing oaten hay exhibited greater feed efficiency and fibre digestion despite low feed intake by feedlot lambs

This study aimed to investigate the feeding effect of wheat silage on growth performance,nutrient digestibility,rumen fermentation,and microbiota composition in feedlot lambs.Sixty-four male crossbred Chinese Han lambs(BW=27.8±0.67 kg,3 months of age)were randomly assigned to four ration groups with wheat silage replacing 0%(WS0),36%(WS36),64%(WS64),and 100%(WS100)of oaten hay on forage dry matter basis.The concentrate-to-forage ratio was 80:20 and the feeding trial lasted 52 d.Increasing wheat silage inclusion linearly decreased dry matter intake by 4%to 27%(P<0.01).However,increasing the wheat silage replacement of oaten hay by no more than 64%improved the feed efficiency by 14%as noted by the feed-to-gain ratio(P=0.04).Apparent digestibility of organic matter(P<0.01),neutral detergent fibre(P=0.04)and acid detergent fibre(P<0.01)quadratically increased.Ammonia nitrogen(P=0.01)decreased while microbial protein production(P<0.01)increased with the increase of wheat silage inclusion.Total volatile fatty acids concentration increased quadratically with the increase of wheat silage inclusion(P<0.01),and the highest occurred in WS64.The molar proportion of acetate(P<0.01)and acetate-to-propionate ratio(P=0.04)decreased while butyrate(P<0.01)and isovalerate(P=0.04)increased.Increasing wheat silage inclusion increased the Firmicutes-toBacteroidota ratio by 226%to 357%,resulting in Firmicutes instead of Bacteroidota being the most abundant phylum.The relative abundance of cellulolytic Ruminococcus numerically increased but that of amylolytic Prevotella(P<0.01)decreased as increasing wheat silage inclusion.Taken together,increasing wheat silage replacement of oaten hay by no more than 64%exhibited greater feed efficiency and fibre digestion despite low feed intake by feedlot lambs due to the change of Firmicutes-to-Bacteroidota ratio in the rumen.