Hypoxia in coastal waters is a pressing ecological problem caused by continued eutrophication and climatic change that has widespread consequences for metazoan life and biogeochemical cycles. Numerous studies have investigated the controls on seasonal hypoxia formation and persistence in many of the world’s large estuaries and coastal hypoxic zones, but far fewer studies have examined the controls on short-term oxygen variability that leads to diel-cycling hypoxia in shallow-water environments. We utilized a unique, comprehensive (181 stations) record of dissolved oxygen concentrations collected at shallow water sites (primarily < 2 m) at high frequency (15 min) throughout the estuarine complex of the Chesapeake Bay and its tributaries to quantify how internal and external variables co-varied with dissolved oxygen. We used a combination of time-series analysis, harmonic analysis, and machine learning (e.g., classification and regression trees (CART)) approaches to identify spatial patterns in major controls on oxygen variability and the duration of moderate hypoxia. We found that key controls on oxygen variability varied substantially over space. For example, photosynthetically active radiation (PAR) was a strong predictor of oxygen dynamics in the majority of mesohaline waters. In more fetch-exposed stations, wind strongly controlled hypoxic duration, but in eutrophic, inshore locations, chlorophyll a, or turbidity were often better predictors. Specifically, diel oxygen variability was muted in upstream regions characterized by high turbidity. The duration of low oxygen conditions, which we defined conservatively as less than 4.8 mg O2 L−1 (156 µM), was strongly controlled by temperature, and simple projections of regional warming and CART-derived oxygen thresholds suggest that the Bay could experience a 10

The purpose of this paper is to provide an update on technology developments that demonstrate feasible alternatives to the manufacture of CFC and halogenated ABA flexible polyurethane foams. A number of approaches will be presented along with a discussion regarding how they can be used by foam producers to reduce or eliminate the need for these materials

Tested standardized procedures for handling premixes and mineral supplements from time of sampling to time of analysis for vitamin A have not been developed, which could account for some unexplained inconsistent and low analytical results. Grinding premix samples and storing them in a freezer for one month had little effect on amount of vitamin A found, but there was a significant loss (about 10%) after storage for one month at room temperature. Results on replicated determinations of vitamin A in unground and ground mineral supplements and on effect of storage were somewhat more variable than for premixes, but only the loss (about 12%) during storage for one month at room temperature was significant.

Biochemical and nutritional properties of high-moisture sorghum grain treated with 1.5% propionic acid or 0.6 or 1.2% of a combination of 6 parts propionic acid and 2 parts each of acetic and benzoic acids were studied. Acid treatment increased the concentrations of reducing sugars (considered a non-enzymatic effect from lack of inherent diastatic activity) and several free amino acids, somewhat reduced the activity of alpha-amylase added to the grain, and increased the in vitro digestibility by pepsin-pancreatin of proteins in the grain. Tests using weanling rats showed no significant differences in protein efficiency ratios, relative nutritive values, or biological values of proteins from control and treated sorghum grains. Diets prepared with treated grain decreased absorption of iron in weanling rats.

Selected blue-color developing reagents for determining vitamin A, effects of some carotenoids, tocopherol, and sterols commonly found in vitamin A extracts of feeds and foods, and effects of moisture and light on the colors developed under normal laboratory conditions were studied. Similar blue colors were obtained using SbCl3, CF3COOH, and CCl3COOH in solutions of CHCl3, CH2Cl2 and C2H4Cl2. In general, the reagents in CH2Cl2 solutions produced the most stable blue colors. The CCl3COOH-in-CH2Cl2 reagent developed slightly higher initial color, but CCl3COOH, especially in CHCl3 solution, was the least stable reagent. Small amounts of moisture affected only SbCl3 reagents, by forming cloudy solutions and precipitates. Carotene and monohydroxy and dihydroxy carotenoids reacted with all reagents tested to produce bluish colors, which, however, reached maximum development much later than the vitamin A blue colors. The presence of sterols slightly decreased color production of vitamin A solutions and frequently slightly increased rate of fading, especially for SbCl3 reagents. With proper precautions any of the reagents studied may be used to determine vitamin A. The preferred reagent for general use probably is CF3COOH-in-CH2Cl2, but it is not the most economical.

Thermoalkali-processed soy protein concentrates (experimental soy concentrate) were compared with sodium caseinate and a commercial soy protein concentrate (Promocaf) as protein sources in milk replacers, supplying .75 of the protein in 20%-protein replacers. Week-old Holstein calves were fed the replacers in two 4-wk trials. Average gains of calves fed experimental soy concentrate (processed 5min at 85C and pH 10.5), caseinate, and Promocaf replacers were 3.0, 6.6, and 6.6kg. Calves fed experimental soy concentrate replacers heated for shorter or longer times lost .8 to 3kg weight during the first 2 wk but gained .6 to 1.7kg during the, last 2 wk. Occasionally calves had loose feces, mainly during the first 2 wk, with no significant differences between groups. Efficiency with which rats used protein of nonfat, spray-dried, milk-replacer ingredients correlated .96 with growth of calves fed corresponding replacers. Growths and protein efficiency ratios were similar when rats were fed lyophilized, thermoalkali-processed soy products heated for various times up to 1h at either 85C and pH 10.5 or 75C and pH 9. Rats fed the experimental soy concentrate performed satisfactorily; calves, less satisfactorily. The protein efficiency ratio of experimental soy products determined with rats correlated .68 with in vitro protein digestibility, −.60 with soluble nitrogen, and −.59 with trypsin inhibitor activity.

Abstract The official final action method for determining vitamin A in mixed feeds, 39.008–39.013, was simplified where possible, principally in extraction and transfer procedures and by omission of chromatography, and was modified to apply to a larger variety of feed and food products. Twenty-two analysts of various degrees of experience participated in the collaborative study of the method, using 6 products. After outliers were eliminated by the Dixon test, data were analyzed and averages were compared with amounts of vitamin A known to be, or estimated, in each sample. The average, per cent deviation from added amount, standard deviation, and coefficient of variation, respectively, on each sample were: breakfast cereal (Sample 1), 23.8 μg/g, 2% less, 3.08, 13% ; mixed feed (or premix), 12.6 μg/g, 5% less, 0.99, 8%; mixed feed containing carotenoid pigments (Sample 3 ), 4.5 μg/g, 3% more, 0.66, 15%; mixed feed without pigments, 4.5 μg/g, 3% more, 0.57, 13% ; liquid feed supplement, 11.4 μg/g, 9% less, 1.44, 12%; powdered breakfast drink, 19.6, 7% less, 1.91, 10%. Some analysts did not correct for pigments in Samples 1 and 3, or for losses on analysis, which could account in part for the degree of variation and for the lower values on some samples. The method has been adopted as official first action to replace 39.008-39.013.

Abstract The present official final action method for determining vitamin A in feeds, 39.008–39.013, was simplified where possible and modified to provide alternative procedures so that it could be used to analyze different types of feed and food products. Among the changes were the following: making fewer extractions, solution transfers, and dilutions to volume; using smaller aliquots; and eliminating chromatography. There was less change in the method for samples of low vitamin A content and those containing carotenoid pigments. A biopotency test was added to provide a basis for converting analytical values of vitamin A stated in μg to USP units.

Abstract Liquid feed concentrates and supplements were analyzed for total vitamin A content, and relative biopotencies were calculated from maleic values determined on those products. The initial relative biopotencies were from 65 to 97% for concentrates and 57 to 85% for supplements. Even when total vitamin A content decreased, storage up to 47 weeks had relatively small effect on relative biopotencies. A single correction factor could not be applied to relate vitamin A analytical data to vitamin A biopotency. Small quantities of anhydroretinol, vitamin A ether, and other unidentified types of vitamin A were found in several liquid feed products. On some samples spectrophotometric determinations yielded values in the same general range as calculated values based on relative biopotencies, but in a few instances the relationship was poor.

Abstract Maleic values were determined on vitamin A extracts from liquid feeds so that estimates could be made of biopotency of the vitamin A; the AOAC method is not suitable for this assay. Biopotencies were 57–81% of total vitamin A found. For comparison, maleic values were determined on Vitamin A Reference Solution and on chicken, quail, and rat livers. Most vitamin A in those sources appeared to be the all-trans form. Results of bioassays of vitamin A in liquid feeds indicate that further work is required before the assays are suitable for comparative purposes with results of biopotency estimates using maleic values.