Sponges have traditionally been viewed as rather unselective filter feeders, and therefore as potential biofilters to remediate microbial water pollution. Here we show that the assumed connection between the ability of sponges to feed on microbes and the potential biotechnological use of such an ability to reduce microbial pollution is more complex than assumed. In a laboratory feeding experiment combined with a transmission electron microscopy study, we assessed the potential of the marine sponge Hymeniacidon perlevis to ingest and digest 3 common pathogenic microbes occurring in coastal waters: 2 bacteria (Escherichia coli and Vibrio anguillarum), and 1 marine yeast Rhodotorula sp. All 3 microbes were ingested by the sponge, but selectively, at different rates and following different cellular mechanisms. Yeast cells were processed very atypically by the sponge. Differences in the ingestion and digestion pathways led to large differences in the effectiveness of the sponge to remove the microbes. While sponge grazing reduced the concentration of E. coli and Rhodotorula sp. to levels far below the initial values, sponges were ineffective in abating concentrations of the most infective bacterium, V. anguillarum. This bacterium, which was digested more slowly than E. coli, proliferated in the experimental flasks at much higher rates than it was grazed. These findings raise the question whether sponges are suitable for bioremediation of microbial pollution, since selective or preferential ingestion of certain bacteria by sponges may end up fueling growth of those grazed less, such as Vibrio spp.

Two experiments were conducted to determine the effects of rancidity and FFA in choice white grease (CWG) on growth performance and nutrient digestibility in nursery pigs. In Exp. 1,150 crossbred pigs (average initial BW of 6.8 kg and average initial age of 21 d) were used. Treatments (as-fed basis) were a corn-soybean meal-based control with no added fat, 6% CWG, and 6% CWG heated at 80 degrees C, with oxygen gas bubbled through it at 849 mL/min for 5, 7, 9, or 11 d. Peroxide value for the CWG increased as oxidative exposure was increased from 0 to 7 d (i.e., peroxide values of 1, 40, and 105 mEq/kg for d 0, 5, and 7, respectively), but decreased to 1 mEq/kg as the hydroperoxides decomposed after 9 and 11 d of oxidation. Pigs fed the control diet (no added fat) had the same (P = 0.91) overall ADG (d 0 to 35) but lower G:F (P < 0.04) than pigs fed diets with added fat. As for the effects of fat quality, ADG (linear effect, P < 0.01) and ADFI (linear effect, P < 0.001) decreased as the fat was made more rancid. However, there were no changes in digestibility of fatty acids as the rancidity of the fat was increased (P = 0.16), suggesting that the negative effects of rancidity were from decreased food intake and not decreased nutrient utilization. In Exp. 2, 125 crossbred pigs (average initial BW of 6.2 kg and average initial age of 21 d) were used to determine the effects of FFA in CWG on the growth performance and nutrient digestibility in nursery pigs. Treatments (as-fed basis) were a corn-soybean meal-based control with no added fat, 6% CWG, and 6% CWG that had been treated with 872, 1,752 or 2,248 lipase units/g of fat. The FFA concentrations in the CWG were increased from 2% with no lipase added to 18, 35, and 53% as lipase additions were increased. Pigs fed the control diet (no added fat) had the same (P = 0.30) overall ADG (d 0 to 33) but lower G:F (P < 0.01) than pigs fed diets with added fat. There were no effects of FFA concentration on ADG (P = 0.18), and ADFI increased (linear effect, P < 0.04) as FFA concentration in the CWG increased. Fatty acid digestibility was not affected (P = 0.17) by FFA in the diet. In conclusion, our data suggest that as fat is oxidized (especially to peroxide values greater than 40 mEq/kg), ADG and ADFI in nursery pigs will decrease; however, FFA concentrations of at least 53% do not adversely affect utilization of CWG in nursery pigs.

One hundred fifty-three sows (average parity of 2.2) were used to determine the effects of dietary electrolyte balance (calculated as mEq/kg of diet for Na + K - Cl) on sows and their litters during lactation. The sows were fed corn-soybean meal-based diets (1.0% lysine, 1.0% valine, 0.95% Ca, and 0.80% P; as-fed basis) starting on d 109 of gestation and throughout the 21-d lactation experiment. Dietary electrolyte balance (dEB) was 0, 100, 200, 350, and 500 mEq/kg (as-fed basis), well above and below the dEB of 185 mEq/kg found in a simple corn-soybean meal-based lactation diet. To achieve the desired dEB, diets had the following: 1) 1.8% HCl (6 N) and 1.06% CaCl2, 2) 1.0% CaCl2, 3) 0.04% NaHCO3, 4) 1.29% NaHCO3, and 5) 2.54% NaHCO3 (as-fed basis). Increasing dEB increased blood pH (linear and quadratic effects, P < 0.001), partial pressure of carbon dioxide (linear effect, P < 0.001), HCO3- concentration (linear and quadratic effects, P < 0.001), and blood base excess (linear and quadratic effects, P < 0.001). However, increased dEB resulted in lower blood concentrations of K (linear and quadratic effects, P < 0.04), Cl (linear and quadratic effects, P < 0.001), and ionized Ca (linear and quadratic effects, P < 0.001). Changing dEB did not affect ADFI; water usage, litter weight gain; sow weight change; sow backfat change; percentages of CP, lactose, and fat in the milk; percentage of sows returning to estrus; days to estrus; and number of pigs born alive in the subsequent litter (P = 0.06). However, piglet survivability to d 10 and overall was greatest with the lower dEB treatments (linear effect, P < 0.05). The pH (linear and quadratic effects, P < 0.001) and colony forming units of total bacteria (linear effect, P < 0.03) in the urine increased as dEB of the diet was increased. In conclusion, dEB had pronounced effects on the physiological status of sows and decreasing dEB below that in a simple corn-soybean meal-based diet decreased bacterial counts in the urine and increased piglet survivability. However, milk composition, sow and litter weights at weaning, and subsequent rebreeding performance of the sows were not affected by dEB.

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The importance of robot contact operation control has been increasing recently due to a need for robots to interact more with the outside world. However, traditional robot compliance control cannot take both transient contact force overshoots and steady-state force tracking error problems into account. To address this problem, this paper aims to design a dynamic adaptive hybrid impedance (DAHI) controller to deal with dynamic contact force tracking in uncertain environments (e.g., polishing scenarios). Under the premise of analyzing the transient response and steady-state error in the hybrid impedance control (HI) and adaptive hybrid impedance (AHI) control, the DAHI control, which combines the advantages from HI and AHI control, is applied to improve the performance of AHI controller. The main goal of such a controller is to avoid force overshoots in the contact stage while maintaining force tracking error in the dynamic tracking stage. The proposed controller is capable of adapting its update rate parameter online in order to track a reference force in uncertain environments. Besides, it does not require any modeling or estimation of an environment's dynamics or the robot's dynamics. The simulation and experimental results both show the achieved control performance. The results have also been compared with the previous control methods.INDEX TERMS Contact operation control, dynamic adaptive hybrid impedance control, force tracking, force overshoots avoidance, industrial application.

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Xylanase has been demonstrated to improve growth performance of broilers fed wheat- or corn-based diets due to its ability to degrade arabinoxylans (AX). However, content and structure of AX in corn and wheat are different, comparing effects of xylanase on cecal microbiota of broilers fed corn- or wheat-based diets could further elaborate the mechanism of the specificity of xylanase for different cereal grains. Thus, a total of 192 one-day-old broilers were randomly allotted into four dietary treatments, including wheat-soybean basal diet, wheat-soybean basal diet with 4,000U/kg xylanase, corn-soybean basal diet, and corn-soybean basal diet with 4,000U/kg xylanase to evaluate interactive effects of xylanase in corn- or wheat-based diets on broilers cecal microbiota during a 6-week production period. The results indicated that bacterial community clustering was mainly due to cereal grains rather than xylanase supplementation. Compared with broilers fed wheat-based diets, corn-based diets increased alpha-diversity and separated from wheat-based diets (p&lt;0.05). Xylanase modulated the abundance of specific bacteria without changing overall microbial structure. In broilers fed wheat-based diets, xylanase increased the abundance of Lactobacillus, Bifidobacterium, and some butyrate-producing bacteria, and decreased the abundance of non-starch polysaccharides-degrading (NSP) bacteria, such as Ruminococcaceae and Bacteroidetes (p&lt;0.05). In broilers fed corn-based diets, xylanase decreased the abundance of harmful bacteria (such as genus Faecalitalea and Escherichia-Shigella) and promoted the abundance of beneficial bacteria (such as Anaerofustis and Lachnospiraceae_UCG_010) in the cecum (p&lt;0.05). Overall, xylanase supplementation to wheat- or corn-based diets improved broilers performance and cecal microbiota composition. Xylanase supplementation to wheat-based diets increased the abundance of butyrate-producing bacteria and decreased the abundance of NSP-degrading bacteria. Moreover, positive effects of xylanase on cecal microbiota of broilers fed corn-based diets were mostly related to the inhibition of potentially pathogenic bacteria, and xylanase supplementation to corn-based diets slightly affected the abundance of butyrate-producing bacteria and NSP-degrading bacterium, the difference might be related to lower content of AX in corn compared to wheat.