Solvent extraction used in industrial separation of rare earths

The total reflux method as applied to the separation of rare earth elements is outlined with reference to extractants Versatic 911, tributyl phosphate and di-2-ethylhexyl phosphoric acid. Industrial solvent extraction processes are described for the production of pure compounds of lanthanum, praseodymium, neodymium, samarium, europium, gadolinium and yttrium.     

African Americans and anxiety disorders research: Development of a testable theoretical framework.

Examines research conducted with African Americans suffering with a Diagnostic and Statistical Manual of Mental Disorders-diagnosed anxiety disorder. Authors first examine previous epidemiological and treatment outcome studies in an effort to ascertain the consistencies and inconsistencies that exist within the literature. A preliminary theoretical framework is provided which can account for previous discrepant findings, and, by incorporating both racial identity and acculturation into its definition of ethnicity, also allows investigators to generate testable hypotheses regarding the manifestation and presentation of anxious symptoms, and to evaluate the efficacy of psychological interventions among African Americans. Suggestions for future investigations in this area are also offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

alpha1-adrenergic-receptor responsiveness in skeletal muscle during dynamic exercise

Attenuation of sympathetic vasoconstriction (sympatholysis) in working muscles during dynamic exercise is controversial. One potential mechanism is a reduction in alpha1-adrenergic-receptor responsiveness. The purpose of this study was to examine alpha1-adrenergic-receptor-mediated vasoconstriction in resting and working skeletal muscles by using intra-arterial infusions of a selective agonist. Seven mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs and a catheter in one femoral artery. A selective alpha1-adrenergic-receptor agonist (phenylephrine) was infused as a bolus into the femoral artery catheter at rest and during exercise. All dogs ran on a motorized treadmill at two exercise intensities (3 and 6 miles/h). Intra-arterial infusions of the same effective concentration of phenylephrine elicited reductions in vascular conductance of 76 +/- 4, 76 +/- 6, and 67 +/- 5% (P > 0.05) at rest, 3 miles/h, and 6 miles/h, respectively. Systemic blood pressure and blood flow in the contralateral iliac artery were unaffected by phenylephrine. These results do not demonstrate an attenuation of vasoconstriction to a selective alpha1-agonist during exercise and do not support the concept of sympatholysis.     

Short-term group therapy for couples in a health maintenance organization.

Describes a 15-session group treatment program for couples in a health maintenance organization (HMO). The program demonstrates principles of efficiency, economy, integration of services, and prevention in an HMO. It is argued that the location of the program in a comprehensive organized health care setting enhances the efficacy of the treatment. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The breakdown into nitric oxide of compounds potentially derived from nitrite in a biological matrix

Summary N-Nitroso compounds can be determined using a chemiluminescence analyzer by means of the nitric oxide liberated as a volatile product of their denitrosation using hydrogen bromide [1, 2]. Much of the nitrite present in or added to a food matrix can be lost even during storage in a refrigerated condition and thus the possibility arises of its conversion into compounds other than nitrosamines and nitrosamides which could also give rise to nitric oxide under, for instance, thermal degradation. Among compounds potentially formed from nitrite that have been studied in relation to their breakdown to nitric oxide have been included an alkyl nitrate, an alkyl nitrite, an amine oxide, an azoxy compound, a nitramine, a nitro guanidine, a nitrolic acid, a nitrone, an oxime, a pseudonitrole, a pseudonitrosite, a thionitrite, a thionitrate as well as C-nitro and C-nitroso compounds. Only in the case of the nitrolic acid and the thionitrate was it likely that interference with the determination of N-nitroso compounds could occur to any considerable extent.

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Abspaltung von NO aus möglichen Folgeprodukten von Nitrit in einer biologischen Matrix

Zusammenfassung N-Nitrosoverbindungen können durch die Chemiluminiscenz-Methode über das Stickoxid bestimmt werden, das durch Denitrosierung mit HBr als flüchtiges Produkt entsteht. Ein großer Teil des Nitrits, das in Lebensmitteln enthalten ist oder zugesetzt wurde kann auch bei Kühllagerung bereits verloren gehen und in andere Produkte als Nitrosamine oder Nitrosamide umgewandelt werden, die bei der thermischen Zersetzung zur Bildung von NO Anlaß geben. Unter den mit Nitrit entstehenden Verbindungen, die zu einer Abspaltung von NO führen könnten, wurden näher untersucht ein Alkylnitrat, ein Alkylnitrit, ein Aminoxyd, eine Azoxy-Verbindung, ein Nitramin, ein Nitroguanidin, eine Nitrolsäure, ein Nitron, ein Oxim, ein Pseudonitrol, ein Pseudonitrosit, ein Thionitrit, sowie C-Nitro- und C-Nitroso-Verbindungen. Nur bei der Nitrolsäure und bei Thionitrat könnte eine Störung der Bestimmung von N-Nitrosoverbindungen über die NO-Abspaltung in beachtlichem Umfang eintreten.

     

Refractory Glass and Glass Ceramic Tube Seals

Complex vacuum-tube envelopes are required to house and support integrated thermionic circuits (ITC) during long-term operation at elevated temperatures. Li2O-ZnO-SiO2 glass ceramic and CaO-A12O3 glass seals were investigated because they are refractory, moldable, have relatively high thermal expansion coefficients, and bond directly to a variety of metals.     

The mechanical properties of lettuce: A comparison of some agronomic and postharvest effects

Mechanical properties data of Iceberg lettuce leaves are described in relation to the applied agronomic variables and post-harvest treatment. Leaf tissue strength and stiffness were both reduced significantly in plants grown with 120 kg/ha applied nitrogen compared with plants grown with 0 kg/ha applied nitrogen. Leaf tissue strength and stiffness were increased significantly in plants grown with added calcium at 80 kg/ha. Significant reductions in stiffness and increases in failure strain were associated with reduced hydration. These findings show that agronomy changes in mechanical properties are as large as maturity and post harvest induced turgor changes, which has implications for both quality and damage of cut salads.