The Athy—Heckel equation applied to granular agglomerates of basic tricalcium phosphate [3Ca3PO4)2·Ca(OH)2]

It is shown that direct compression grade tricalcium phosphate yields linear Heckel plots only if the particle density used is that obtained by liquid pycnometry or mercury porosimetry. If the true density is used (i.e. that obtained by gas displacement), then linearization is not obtained in a pressure range where bonding evidently occurs. It is shown that the pore volume in the range of diameters from 0.5 to 2 μm decreases as tableting pressure increases, and that bonding is associated with the loss of pores of this size.     

Solid-state13C NMR investigations of insoluble deposits in aromatic bitters

Insoluble deposit formed in aromatic bitters produced from alcoholic extracts of about 30 different botanical materials with a dry matter content of 1.67% and 38 vol% alcohol and a characteristic astringent flavour was shown by¹³C NMR spectroscopy to be a coprecipitate of plant polyphenols, proteins and carbohydrates. The polyphenols in the deposit were flavonoids such as anthocyanidins and anthocyanins, with glucose as the principal carbohydrate and derivatives of cinnamic acid. The deposit formation in the aromatic bitters was accelerated by addition of the radical initiator 2,2′-azobis(2-amidinopropane) dihydrochloride or by addition of hydrogen peroxide in combination with iron(III) nitrate and ascorbic acid as a Fenton reagent. Polymerization of catechin and pelargonidin was shown, in model experiments, to be oxidative and to be accelerated by exposure to light. A mechanism involving oxidative polymerization of polyphenols followed by coprecipitation of polymerized polyphenols, proteins and carbohydrates is proposed for formation of deposits in alcoholic beverages of the bitters type.     

An adaptive non‐conforming finite‐element method for Reissner–Mindlin plates

Adaptive algorithms are important tools for efficient finite‐element mesh design. In this paper, an error controlled adaptive mesh‐refining algorithm is proposed for a non‐conforming low‐order finite‐element method for the Reissner–Mindlin plate model. The algorithm is controlled by a reliable and efficient residual‐based a posteriori error estimate, which is robust with respect to the plate's thickness. Numerical evidence for this and the efficiency of the new algorithm is provided in the sense that non‐optimal convergence rates are optimally improved in our numerical experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

On some interval methods for algebraic,exponential and trigonometric polynomials

New inclusion methods for the simultaneous determination of the zeros of algebraic, exponential and trigonometric polynomials are presented. These methods are realized in real interval arithmetic and do not use any derivatives. Using Weierstrass' correction some modified methods with the increased convergence rate are constructed. Convergence analysis and numerical example are included.     

Linearization of Drug Delivery from Sustained-Release Dosage Forms, Synthetic Gel Systems

A linear, apparent zero-order, in vitro release profile may be approximated from triple-pressed tablets using synthetic gum systems in the first and second press coats. This is coupled with varying concentrations of the actives (Melperone HCl. Diethylpropion HCl, and Dyphylline) in the core and press coats. The approximately linear release function obtained from these tablet systems is in stark contrast to a supposedly prolonged release tablet (comparative formulation) from the literature, which actually releases by the square root of time function characteristic of diffusion control. Addition of a placebo press coat to the outside of the synthetic gum systems simply increases the lag times for release (while the placebo coat is undergoing hydration, etc.). The linearity following the lag is reminiscent of saturation kinetics. Results suggest that the almost linear release profile is a function of the concentration of the various layers (core first and second press coats) coupled with the gelation characteristics of the synthetic gums. This zero order release does not hold for the systems of the comparative formulation taken from the patent literature.     

Notch sensitivity of thermoset and thermoplastic laminates loaded in tension

Inplane tensile fracture of unnotched and notched thermoset graphite-epoxy and thermoplastic graphite-PEEK composite laminates is examined. Both fibre-dominated quasi-isotropic and matrix dominated ±45 angle-ply layups were investigated.Classical lamination theory predictions of elastic and strength properties of unnotched specimens are compared with experiments. Several notched geometries, i.e. centre-notched, double-edge notched and open-hole specimens subjected to tensile loading to fracture were examined. The notched strength of the quasi-isotropic laminates was analysed by a damage zone model, where damage around the notch is represented by an equivalent crack with cohesive force acting between the crack surfaces.Good agreement between experimental and calculated strength was observed for the graphite-epoxy laminates which failed in a collinear manner. For the graphite-PEEK laminates discrepancies between predicted and experimental strength are related to observed deviations from collinear crack growth. The angle-ply graphite-PEEK laminates showed larger notch sensitivity than the corresponding graphite-epoxy, probably due to less degree of stress relieving damage formation around the notch.     

Storage life of frozen salmonoids Effect of light and packaging conditions on carotenoid oxidation and lipid oxidation

Summary The combined effect of oxygen transmission of packaging material and of exposure to light with different spectral distribution on the oxidative degradation of carotenoids and lipids in frozen salmonoids has been characterized in a storage experiment with steaks of rainbow trout. The degradation of the carotenoid astaxanthin, as followed by HPLC analysis and tristimulus colorimetric measurement, was sensitive to the radiant flux density of UV light and less sensitive to the oxygen transmission rate of the packaging material, in agreement with previous findings for photooxidation of carotenoids in food model systems. This is in contrast to the lipid oxidation, which was found to be dependent on the accessability of oxygen rather than on exposure to UV light. Formation of peroxides in the product culminated after 3 months of storage (up to 8.4 mEq kg^–1 oil), and preceded the formation of thiobarbituric-acid-reactive substances. The product in packaging material with a high oxygen transmission rate (60 cm³ m^–2 bar^–1 per 24 h) reached a level of approximately 5 mol malonaldhyde/kg^–1 product, when stored exposed to standard fluorescent light or fluorescent light with a high UV component. Rancid taste was not detected by sensory evaluation for any of the products after 6 months of storage, whereas a bitter taste was noted for the product exposed to UV light.

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Die Haltbarkeit von Lachsforellen Einfluß von Licht und Verpackung auf die Carotenoid- und Fettoxydation

Zusammenfassung Der kombinierte Effekt von Sauerstoffdurchgang durch Verpackungsmaterial und der Lichteinwirkung verschiedener spektraler Verteilung auf den oxidativen Abbau der Carotinoide und Fette in gefrorenen Lachsforellen wurde in einem Lagerungsversuch untersucht. Der Abbau des Carotenoids Astaxanthin wurde mit HPLC undTristimulus-Calorimetrie beobachtet, und war empfindlich gegenüber UV-Licht und weniger empfindlich gegenüber der Sauerstoffdurchlässigkeit der Verpackung, was mit früheren Ergebnissen für Photooxidation der Carotinoide in Modellsystemen übereinstimmt. Dies widerspricht der Fettoxidation, die mehr von Sauerstoffzugang abhängig ist als von der Entwicklung des UV-Lichtes. Die Bildung von Peroxiden des Produktes kuliminierte nach 3monatiger Lagerung (bis 8,4 meq/kg Öl) und ging der Bildung von Thiobarbitursäure-aktiven Substanzen voraus. Das Produkt im Material mit hohem Sauerstoffdurchgang (60 cm³ m^–2 bar^–1 pro 24 h), das bei normalen fluorescierendem Licht oder bei fluorescierendem Licht mit hohem UV-Anteil aufbewahrt wurde, erreichte einen TBS-Wert von ungefähr 5 mol Malonaldehyd/kg Fleisch. Ein ranziger Geschmack wurde durch sensorische Bewertung nach 6monatiger Lagerung nicht erkannt, wohl aber ein bitterer Geschmack bei dem UV-Licht ausgesetzten Proben.

     

Emission of excited potassium species from an industrial iron catalyst for ammonia synthesis

The angular dependence of potassium emission-desorption is studied from a fused iron catalyst of the type used for ammonia synthesis. The excited species (K^*, K _n ^* , etc.) and positive ions K⁺ have strongly different angular distributions. The bilobular distribution measured for ion desorption is concluded to be either due to excited atoms, so-called Rydberg atoms, or excited clusters. Both types of species have to desorb from the edges of the sample and become field ionized and deexcited just outside the sample, as reported in previous studies on an iron oxide catalyst. The peak in the normal direction measured for excited species is due to excited cluster formation outside the catalyst surface. Similarities with previous results for other catalysts are observed. The possibility that the promoter function of potassium in the ammonia synthesis is due to excited species is pointed out.On leave from Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Cracow, Poland.     

Acid-catalysed reduction of ferrylmyoglobin: product distribution and kinetics of autoreduction and reduction by NADH

The pH dependence of iron(II)/iron(III) product distribution, following reduction of the hypervalent iron in equine ferrylmyoglobin by the protein moiety of the pigment (so-called autoreduction) and by NADH (nicotinamide adenine dinucleotide, reduced) and the rate of reduction was found to depend different on pH. Autoreduction is specific acid catalysed and has a more modest temperature dependence than autoxidation of oxymyoglobin, with the activation parameters H ^#=58.5±0.4 kJ·mol^–1 and S ^#=2.7±0.1 J·mol^–1·K^–1 in 0.16 mol·1^–1 NaCl. The product of autoreduction is the iron(III) pigment metmyoglobin, which is slightly modified in the protein moiety. The reaction has a positive kinetic salt effect from which it is deduced that the reactive centre of ferrylmyoglobin has a charge of +1 in agreement with the structure Fe(IV)=O. Reduction by NADH involves parallel reactions of two pigment forms in acid/base equilibrium with each other with a pK _a equal to 4.9, both forms yielding metmyoglobin as well as the iron(II) pigment, oxymyoglobin, as products. The protonated form reacts faster than the deprotonated form, and two-electron transfer has greater importance for the protonated form with a limiting Fe(II)/Fe(III) product ratio of 0.6 in acidic solution compared to 0.12 in alkaline solution. A square root dependence of rate on NADH concentration suggests involvement of NAD·radicals with a disproportionation as the termination reaction.

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Säure-katalysierte Reduktion von Ferrylmyoglobin. Produktdistribution und Kinetik der Autoreduktion und Reduktion von NADH

Zusammenfassung Die Reaktionsgeschwindigkeit und das Eisen(II)/Eisen(III)-Verhältnis des Produkts nach Reduktion von hypervalentem Eisen in Ferrylmyoglobin aus Pferden zeigt eine unterschiedliche pH-Abhängigkeit der sogenannten Autoreduktion (Reduktion am Proteinteil des Pigments) sowie der Reduktion durch NADH. Die Autoreduktion weist eine spezifische Säure-Katalyse auf sowie eine moderate Temperaturabhängigkeit im Vergleich zur Autooxidation von Oxymyoglobin mit den Aktivierungsparametern H ^#=58.5±0.4 kJ·mol^–1 und S ^#=2.7±0.1 J·mol^–1·K^–1 in 0.16 mol·1^–1 NaCl. Das Produkt der Autoreduktion ist das Eisen(III)-Pigment Metmyoglobin mit leicht modifiziertem Proteinanteil. Die Reaktion hat einen positiv kinetischen Salzeffekt, woraus zu erschließen ist, daß das reaktive Zentrum im Ferrylmyoglobin die Ladung +1 übereinstimmend mit der Struktur Fe(IV)=O besitzt. Die Reduktion durch NADH weist auf parallele Reaktionen von zwei Pigmentformen in einem Säure/Base-Gleichgewicht mit pk _a=4.9 hin, beide Formen ergeben Metmyoglobin sowie das Eisen(II)-Pigment Oxymyoglobin als Produkt. Die protonisierte Form reagiert schneller als die deprotonisierte Form, und eine zwei-Elektronenübertragung hat größere Bedeutung für die protonisierte Form mit einem Fe(II)/Fe(III) Produktverbrauch von 0.6 in der Säurelösung und 0.12 in der Baselösung. Die Quadratwurzel Abhängigkeit der Geschwindigkeit von NADH deutet auf eine Teilnahme von NAD-Radikalen mit Disproportionierung als Schlußreaktion.

     

A little Birdie told me: Social media,organizational legitimacy,and underpricing in initial public offerings

Drawing on the organizational legitimacy literature, we propose and test a set of hypotheses arguing that social media, an artifact of information technology, serves as a mechanism for conferring legitimacy in the market for initial public offerings (IPOs). The extant literature identifies third-party authorities, such as traditional media outlets and industry analysts, as a valuable source of organizational legitimacy. Social media and micro-blogging, however, remain outside current classifications of the phenomenon. This study theoretically develops and empirically tests a new mechanism in the legitimation process: the direct interaction with potential investors and society-at-large via social media. Our findings indicate broad support that having a Twitter account, and the extent to which a firm utilizes Twitter, is associated with systematically higher levels of IPO underpricing. Moreover, we find support that social media variables external to the firm, including number of followers and retweets, also impact the level of underpricing in an IPO. In conclusion, we highlight the emerging role of social media in processes of legitimation and invite additional research at the intersection of IS and management.