Long-time Treatments Research Articles

Residual Alkaline Phosphatase Activity in Milks Subjected to Various Time-Temperature Treatments

Milk is routinely tested for proper pasteurization. The Scharer and Fluorophos methods, among others, test for residual alkaline phosphatase (ALP) activity to assure proper pasteurization. Until recently there were no tests available to accurately detect residual ALP activity levels below the U.S. legal limit of 1 μg of phenol or 350 mU of ALP per liter of milk. The new Fluorophos method can detect accurately residual ALP activity levels as low as 10 mU/liter.The Fluorophos method was used to investigate residual ALP activity levels in several fluid milk products. The milk products were thermally processed under various time and temperature protocols below, at, and above current U.S. Food and Drug Administration-mandated heat treatments for fluid milk and milk products. The data established values for residual ALP activity in milks pasteurized under high-temperature short-time (HTST) and low-temperature long-time (LTLT) treatments. The mean ALP activities for whole, 2% lowfat, 1% lowfat, skim, half and half, and chocolate-flavored milks thermally processed at the legal minimum HTST pasteurization treatment are 169.7 ± 12.3, 145.2 ± 9.3, 98.6 ± 8.9, 72.5 ± 4.2, 38.4±4.6 and 157.3±6.5 mU/liter, respectively. The mean ALP activities generated at the legal minimum LTLT pasteurization treatment are 81.8 ± 4.8, 66.4 ± 5.9, 56.4 ± 2.1, 39.1 ± 3.9, 35.0±1.2 and 91.3±7.7 mU/liter, respectively. The values for all milks pasteurized at the legal minimum heat treatment were significantly below the current legal cutoff for residual ALP activity of 350 mU/liter of milk or milk product.

N–3 fatty acids induce oxidative modifications in human erythrocytes depending on dose and duration of dietary supplementation

The present work was performed to study an optimal dose and duration of dietary n-3 polyunsaturated fatty acid (PUFA) supplementation that would not result in harmful modifications of oxidative cell metabolism. Forty healthy subjects were divided into four groups that received 2.5 g/d eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), 5.1 g EPA + DHA/d, 7.7 g EPA + DHA/d, or placebo. Fatty acid composition, tocopherol status, and susceptibility to lipid peroxidation induced in vitro by 2,2'-azobis-(2-amidinopropane) (AAPH) were evaluated in human red blood cell (RBC) membranes on days 30 and 180. n-3 PUFA treatment increased EPA and DHA concentrations in RBC membranes in a time-dependent manner in all of the n-3 PUFA groups. These modifications occurred with concomitant dose- and time-dependent increases in the membrane unsaturation index. After 30 d of treatment with n-3 PUFAs, alpha-to-copherol significantly increased in RBC membranes of the intermediate- and high-dose groups. Because of the higher concentration of this antioxidant in these groups, the susceptibility of RBC membranes to peroxidation was decreased. However, after 180 d of treatment, alpha-tocopherol decreased to baseline values and AAPH-induced lipid peroxidation increased in a dose-dependent manner. These results show that high doses of dietary n-3 PUFAs, as well as long-time treatments, affect human RBC susceptibility to lipid peroxidation by changes in fatty acid composition and tocopherol content.

Microstructural evolution of near-γ TiAl alloys during long-time heat treatments

Near-{gamma} titanium aluminide (TiAl) alloys have potential as lightweight high temperature structural materials for the automotive and aerospace industries. This can be attributed to the material`s low density, good oxidation, resistance, high elastic modulus, and good elevated-temperature strength retention. However, the microstructural evolution of near-{gamma} TiAl alloys during extended heat treatment periods has not been studied in detail and therefore, a comprehensive understanding of these microstructures is not available. This paper focuses on the microstructural response of three powder metallurgy (P/M) near-{gamma} TiAl alloys to long-time heat treatments at temperatures near the {alpha}transus temperature (T{sub {alpha}}). Relevant microstructural features are characterized and T{sub {alpha}} for each alloy is determined.

Ocular hypotensive effects of prostaglandins (PGs) and their analogs

The imidazoline-based ophthalmic drugs oxymetazoline and xylometazoline are widely used as ocular decongestants in pharmaceutical preparations. In this paper, the degradation of these drugs and the model compound 2-methyl-2-imidazoline, was studied in the presence of the vitamin B2 (Riboflavin) and visible light.The photogenerated Riboflavin electronically excited triplet state interacts with oxymetazoline and xylometazoline and as a result different free radicals and reactive oxygen species are produced. These species interact with the drugs in further steps, producing their degradation.Oxymetazoline is more easily photo-degradable than xylometazoline towards reactive oxygen species. Particularly, oxymetazoline reacts four orders of magnitude faster than xylometazoline with singlet oxygen. This fact is due to the presence of an OH-group in the benzene ring of oxymetazoline, increasing the oxidability of the drug. The degradation of xylometazoline by reactive oxygen species becomes more important as its concentration increases. This finding should warn against long-time treatments with xylometazoline. An eventual local accumulation of the drug may cause adverse effects in the ocular organ in the presence of Riboflavin. In parallel, the present results advise for a moderate precaution in relation to light exposure after topical application of the imidazoline derivatives oxymetazoline and xylometazoline.

Nε-(β-aspartyl)lysine

Publisher Summary N ɛ -(β-aspartyl)lysine cross-linking is generally found only in heated proteins. N ɛ -(β-Aspartyl)lysine has also been found in the urine of children with various pathological conditions, but its presence does not appear to be related to specific symptoms. The occurrence of β-Asp-ɛ-Lys links in native wool is doubtful. It is known that proteins from blood serum membranes, may accumulate in colostrum, and it is natural to predict that the products of the reactions catalyzed by these enzymes might also be detected in colostrum. When colostrums was screened for the presence of isopeptide bonds, not only the γ-Glu- ɛ-Lys link, but also the β-Asp-ɛ-Lys link, could be detected, however, only in a limited number of samples. The methods used to detect isopeptides include complete enzymatic digestion of proteins, requiring long-time treatments at pH 2.0 and 8.2. Under these conditions, the rather labile β-Asp-amide bond may well be hydrolyzed to a certain extent and it is, thus, likely that small amounts of this derivative are overlooked.

The influence of long-time stress relief treatments on the dynamic fracture toughness properties of ASME SA508 C1 2a and ASME SA533 Gr B C1 2 pressure vessel steels

Dynamic fracture toughness tests were performed on SA508 Cl 2a and SA533 Gr B Cl 2 parent base materials which had been subjected to one of three longtime post weld type stress relief heat treatments: 48 hours at 1000 °F (538 °C), 24 hours at 1125 °F (607 °C), and 48 hours at 1125 °F (607 °C). Linear elastic Kld results were obtained at low temperatures while Jintegral techniques were utilized to evaluate dynamic fracture toughness over the transition and upper shelf temperature ranges. Loading rates in terms of K averaged 4.14 × 104 ksi√in. per second (4.58 × 104 MPa√m per second). Tensile, Charpy impact, and drop weight nilductility transition tests as well as room temperature, air environment fatigue crack growth rate tests (SA508 Cl 2a only) were also performed. The higher temperature stress relief heat treatments (24 or 48 hours at 1125 °F, 607 °C) decreased the dynamic fracture toughness of SA508 Cl 2a and SA533 Gr B Cl 2 pressure vessel steels. Nevertheless, the dynamic fracture toughness of both base materials exceeded the ASME specified minimum reference toughness KIR curve. Furthermore, the room temperature, air environment fatigue crack growth rate properties of SA508 Cl 2a steel were essentially unchanged by the longtime post weld type stress relief heat treatments.

Rapid Tempering of High Speed Steel

1—Rapid induction tempering of W-Mo high speed steel produces mechanical properties, as indicated by hardness and bend test results, which are approximately equal to those resulting from conventional long-time tempering treatments. 2—Short-time tempering data for high speed steel exhibits a lack of conformance to the tempering parameter T (c + log t). It appears that tempering reactions are accelerated by rapid induction tempering to rates considerably greater than those predicted by the parameter. Plastic deformation or thermal strain during the heating part of the short tempering cycle is thought to be the cause of the tempering anomaly. It is believed that such strain accelerates the tempering reactions during rapid heating so as to place the steel in an advanced state of tempering at the instant the tempering temperature is reached. This advanced state will not proceed significantly until after a period of time depending on the extent of advancement. Induction-tempered, high speed steel which is held at the tempering temperature by short power impulses is found to undergo additional acceleration of the tempering reactions during the holding period. This is thought to be due to small thermal strain produced by the temperature oscillations. By this method of tempering maximum secondary hardness may be reached in at least a few minutes at a temperature which would normally require 1 hr by conventional methods. 3—At maximum secondary hardness, high speed steel which is induction tempered by rapid heating exhibits a slightly greater proportion of retained austenite than does the steel which is conventionally tempered for long times. 4—Maximum bend strength for high speed steel whether tempered rapidly by induction or slowly by salt bath approximately coincides with the completion of the retained austenite transformation.

The Effect of Long‐Time Fertility Treatments on the Nitrogen and Carbon Content of a Prairie Soil1

Agronomy JournalVolume 40, Issue 9 p. 778-785 Article The Effect of Long-Time Fertility Treatments on the Nitrogen and Carbon Content of a Prairie Soil1 Darold A. Dodge, Darold A. DodgeSearch for more papers by this authorH. E. Jones, H. E. Jones Formerly Graduate Student, now Instructor in Soil Survey, and Assistant Professor of Soils, Department of Agronomy, respectively. Grateful acknowledgement is made to staff members and former staff members for collection of data over the period of the experiment and to Dr. H. C. Fryer, Station Statistician, for helpful suggestions in the statistical analysis of the data.Search for more papers by this author Darold A. Dodge, Darold A. DodgeSearch for more papers by this authorH. E. Jones, H. E. Jones Formerly Graduate Student, now Instructor in Soil Survey, and Assistant Professor of Soils, Department of Agronomy, respectively. Grateful acknowledgement is made to staff members and former staff members for collection of data over the period of the experiment and to Dr. H. C. Fryer, Station Statistician, for helpful suggestions in the statistical analysis of the data.Search for more papers by this author First published: 01 September 1948 https://doi.org/10.2134/agronj1948.00021962004000090003xCitations: 5 1 Contribution No. 392 from the Department of Agronomy, Kansas Agricultural Experiment Station, Manhattan, Kans. Also presented before Section IV of the Soil Science Society of America at the annual meeting at Cincinnati, Ohio, November 18, 1947. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume40, Issue9September 1948Pages 778-785 RelatedInformation