Rapid colorimetric determination of free fatty acids

In 1964, a method was described for the determination of free fatty acids (FFAs) in vegetable oil. This paper describes an expansion of that work, improving the sensitivity and reproducibility of the method, as well as examination of solubilities of the copper soaps as a function of chain length and unsaturation. Involvement of the micellar structure was reviewed. Finally, a procedure is described that permits very rapid determination of FFA at the 2.0–14.0 μmol (0.5–4.0 mg oleic acid) level, and the results with several oils are given. Particular attention was given to evaluation of solvent systems which would extract the copper complexes. Presented in part at the AOCS Meeting in San Francisco, April 1969. Technical Paper No. 4036, Oregon Agricultural Experiment Station.     

A simple,sensitive method for lipid phosphorus

A method is described for quantitatively determining lipid phosphorus with a linear range from 0.7–10.0 μg. The method is simple and rapid, requiring one stable reagent and a single extraction with 1-butyl acetate after the phosphorus is converted to inorganic phosphate by means of a perchlorate digestion. The stable complex is read at 310 nm. Technical Paper no. 3777, Oregon Argiculture Experiment Station.     

A rapid automated system for the analysis of dissolved total organic nitrogen in aqueous solutions

An automated system for the analysis of dissolved organic nitrogen has been developed and applied to natural waters. It is based on subjecting sample to u.v. irradiation followed by a heterogeneous reduction of the nitrogen containing irradiation products to ammonia which is detected by an ammonia gas sensing probe. Quantitative recoveries of different organic nitrogen compounds common to natural waters were obtained after 17 min of irradiation. Determination with and without irradiation make possible the separate determination of total and inorganic nitrogen, respectively.     

The role of house staff in undergraduate surgical education

An analysis of the contribution made by house officers in fulfilling the objectives for a comprehensive clerkship experience was undertaken by questioning members of the 1975 medical class. The objectives examined over a broad spectrum of surgical disease and are applicable to any general surgical clerkship. In addition, the instruction received in technical skills was analyzed and deficiencies were noted. Major subject areas related to surgical disease were examined for adequacy of house staff instruction, and an estimation of hours per week devoted to the clerkship experience by house and staff was derived. The university-private hospital training program at this institution permitted a comparison of instruction between these clerkship settings. Some deficiencies did appear in intellectual and technical instruction in both clerkship environments. These deficiencies, however, usually were related to a paucity of patient material and to the lack of opportunity for clinical instruction which ensues from these cases. With few exceptions, the house staff provided nearly one third of the knowledge base acquired during the junior medical student experience. The results indicate that very little difference exists between the didactic role of the house officer in either the university or community hospital environment.     

Long-term transformation and fate of manufactured ag nanoparticles in a simulated large scale freshwater emergent wetland

Transformations and long-term fate of engineered nanomaterials must be measured in realistic complex natural systems to accurately assess the risks that they may pose. Here, we determine the long-term behavior of poly(vinylpyrrolidone)-coated silver nanoparticles (AgNPs) in freshwater mesocosms simulating an emergent wetland environment. AgNPs were either applied to the water column or to the terrestrial soils. The distribution of silver among water, solids, and biota, and Ag speciation in soils and sediment was determined 18 months after dosing. Most (70 wt %) of the added Ag resided in the soils and sediments, and largely remained in the compartment in which they were dosed. However, some movement between soil and sediment was observed. Movement of AgNPs from terrestrial soils to sediments was more facile than from sediments to soils, suggesting that erosion and runoff is a potential pathway for AgNPs to enter waterways. The AgNPs in terrestrial soils were transformed to Ag(2)S (~52%), whereas AgNPs in the subaquatic sediment were present as Ag(2)S (55%) and Ag-sulfhydryl compounds (27%). Despite significant sulfidation of the AgNPs, a fraction of the added Ag resided in the terrestrial plant biomass (~3 wt % for the terrestrially dosed mesocosm), and relatively high body burdens of Ag (0.5-3.3 μg Ag/g wet weight) were found in mosquito fish and chironomids in both mesocosms. Thus, Ag from the NPs remained bioavailable even after partial sulfidation and when water column total Ag concentrations are low (<0.002 mg/L).     

Achieving the ideal strength in annealed molybdenum nanopillars

The theoretical strength of a material is the stress required to deform an infinite, defect-free crystal. Achieving the theoretical strength of a material experimentally is hindered by the ability to create and mechanically test an absolutely defect-free material. Here we show that through annealing it is possible to employ the versatility of the focused ion beam (FIB) but recover a mechanically pristine limited volume. Starting with FIB-milled molybdenum pillars, we anneal them in situ in a transmission electron microscope (TEM) producing a molybdenum pillar with a spherical cap. This geometry allows for the maximum stress to occur in the interior of the spherical cap and is ideally suited for experimentally achieving the ideal strength. During in situ compression testing in the TEM the annealed pillars show initial elastic loading followed by catastrophic failure at, or very near, the calculated theoretical strength of molybdenum.     

Flavonol glycoside distribution in cultivars and hybrids of Leucaena leucocephala

Flavonol glycosides found in the leaves of Leucaena leucocephala comprised the 3-arabinosides, 3-rhamnosides and 3-glucuronides of quercetin and myricetin, and quercetin-3-rhamnosylglucoside, at a total concentration of 3–4%. In cultivars of high productivity (Peru, El Salvador (K28) and Cunningham) all seven compounds occurred with a largely constant pattern of relative concentrations. However in the cosmopolitan form naturalised throughout the tropics the 3-arabinosides were invariably absent. The same feature which was conspicuous on the high performance liquid chromatography trace, occurred with a low frequency (ca 10%) in Peru and Cunningham. The pattern provides a quick method for identifying the provenance of commercial leucaena leaf meal, and also for detecting blending or adulteration with other leaf meals. The flavonol glycoside distribution of those species associated with ‘leucaena’ leaf meal (Acacia villosa, Calliandra calothyrsus, Manihot utilissima and Sesbania grandiflora) is very different, and all have fewer compounds. All compounds occur in the apical tissue of young leucaena seedlings, enabling identification of cultivar from seed in 10 days. Comparison of leaf flavonol patterns for L. leucocephala, L. pulverulenta their known F₁ hybrid, and an entity known locally in Java as ‘L. glabrata’ strongly suggest a hybrid origin for the latter.     

Effects of selenium, vitamins, and ration fiber on placental retention and performance of dairy cattle

One hundred and twenty Holstein cows were assigned to a randomized complete block design to determine effects of selenium, vitamins, and ration fiber on incidence of placental retention and other health and reproductive problems. The selenium treatment (50 mg selenium, 680 IU vitamin E) was administered as a single injection approximately 3 to 4 wk prepartum. The vitamin treatment (3 million IU vitamin A, 450,000 IU vitamin D3, 300 IU vitamin E) consisted of two injections, one administered at 3 to 4 wk prepartum and another at 2 to 3 wk postpartum. Fiber treatments were: control, 15.7% crude fiber; beet pulp, 19.3% crude fiber; and soyhull, 19.0% crude fiber. Feeding of experimental rations was begun 1 day postpartum, and the ration effect on placental retention was examined only at subsequent parturition. The overall placental retention rate of 28% was not affected by either selenium, vitamin, or combined treatments. Ration treatments did not affect the placental retention rate of 42% at subsequent parturition. Cows receiving the soyhull ration required fewer services per conception. Incidence of foot problems tended to be higher in the cows that received the combined selenium and vitamin A, D, E treatments. Supplemental selenium, vitamins A, D, and E, and ration fiber treatments did not reduce incidence of placental retention or improve most other health and reproductive measures.