Improvement of the food value of rice straw is urgently required in rice crop growing areas to mitigate pollution caused by rice straw burning and enhance the supply of high-quality forages for ruminants. The aims of the present study were to compare the effects of fresh corn Stover and rice straw co-fermented with probiotics and enzymes on rumen fermentation and establish the feasibility of increasing the rice straw content in ruminant diets and, by extension, reducing air pollution caused by burning rice straw. Twenty Simmental hybrid beef cattle were randomly allotted to two groups with ten cattle per group. They were fed diets based either on rice straw co-fermented with probiotics and enzymes or fresh corn Stover for 90 days. Rumen fluid was sampled with an esophageal tube vacuum pump device from each animal on the mornings of days 30, 60, and 90. Bacterial diversity was evaluated by sequencing the V4-V5 region of the 16S rRNA gene. Metabolomes were analyzed by gas chromatography/time-of-flight mass spectrometry (GC-TOF/MS). Compared to cattle fed fresh corn Stover, those fed rice straw co-fermented with probiotics and enzymes had higher (P < 0.05) levels of acetic acid and propionate in rumen liquid at d 60 and d 90 respectively, higher (P < 0.05) abundances of the phyla Bacteroidetes and Fibrobacteres and the genera Ruminococcus, Saccharofermentans, Pseudobutyrivibrio, Treponema, Lachnoclostridium, and Ruminobacter, and higher (P < 0.05) concentrations of metabolites involved in metabolisms of amino acid, carbohydrate, and cofactors and vitamins. Relative to fresh corn Stover, rice straw co-fermented with probiotics and enzymes resulted in higher VFA concentrations, numbers of complex carbohydrate-decomposing and H 2utilizing bacteria, and feed energy conversion efficiency in the rumen. It is of great significance to vigorously develop ruminant production in the main grain producing areas to increase the amount of crop straw in ruminant diet, reduce the pollution caused by crop straw burning, and increase the income of farmers and herdsmen. However, feeding large amounts of untreated crop straw to ruminants will reduce their performance and expel large amounts of methane, which not only reduces the energy efficiency of ruminant diet, but also adversely affects the climate 1. Therefore, the key problem to be solved is how to improve the effective fermentation of crop straw and reduce the formation of methane in the rumen while using crop straw to develop ruminant production.
Power Hardware in the Loop (PHIL) systems are used to test a power system with the help of combined software and hardware. Generally, to construct a PHIL system, a switched-mode power amplifier that has a stable performance is used, because of their large, linear signal control-to-output characteristics. However, the fundamental limitations of a switch-mode power amplifier (PA) are the dynamic performance and output bandwidth. In this paper, a compound controller has been used for the rectifier part of a PA, which can ensure the stability of a PA under transient or fault operating conditions. Moreover, a compound controller, which involves a feed-forward controller, a proportional controller and a repetitive controller, is proposed in the inverter part of a PA, and it can be used for PHIL applications. Experimental results are obtained under various operating conditions, such as transient responses under load step change, and output voltage bandwidth testing for a PHIL system, it is concluded that a proposed switched-mode power amplifier is useful for the PHIL system.
Lemon is a fruit with delicious taste and attractive flavor, which has been widely accepted by people over the world. Dry lemon slice is a classical processed product of lemon. It is readily to be browning during storage. Which chemicals are responsible for the browning behavior remains unclear. Therefore, in this work, nuclear magnetic resonance spectroscopy is used to analyze the metabolites changes in dry lemon slice during storage. Nineteen metabolites were identified and their related levels were statistically calculated by principal component analysis. The first principal components were represented by glutamic acid, -amino-butyric acid, -amino-butyric acid, alanine, limonoid, citric acid, glutamine, and phosphocholine. The changes of browning degree during storage and its correlations with the levels of polyphenol, ascorbic acid, amino acid nitrogen, and 5-hydroxymethylfurfural were analyzed. The results indicated that Maillard reaction and oxidation of phenolics were two main processes contributing to the nonenzymatic browning during storage.
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