Geschäftsmodelle

The business model concept, although a relatively new topic for research, has garnered growing attention over the past decade. Whilst it has been robustly defined, the concept has so far attracted very little substantive research. In the context of the wide-spread digitization of businesses and society at large, the logic inherent in a business model has become critical for business success and, hence, a focus for academic inquiry. The business model concept is identified as the missing link between business strategy, processes, and Information Technology (IT). The authors argue that the BISE community offers distinct and unique competencies (e.g., translating business strategies into IT systems, managing business and IT processes, etc.) that can be harnessed for significant research contributions to this field. Within this research gap three distinct streams are delineated, namely, business models in IT industries, IT enabled or digital business models, and IT support for developing and managing business models. For these streams, the current state of the art, suggest critical research questions, and suitable research methodologies are outlined.     

NMR chemical shift reagents in structural determination of lipid derivatives: IV. Methylcis- andtrans-9,10-epoxystearate and methylerythro- andthreo-9,10-dihydroxystearate

Chemical shift reagents were used to expand the amount of structural information obtainable from NMR studies of derivatives of methyl oleate and elaidate:methylcis-9,10-epoxystearate, methyltrans-9,10-epoxystearate, methyl erythro-9,10-dihydroxystearate, and methyl threo-9,10-dihydroxystearate. Chemical shift reagent studies of methyltrans-9,10-epoxystearate and methyl threo-9,10-dihydroxystearate afforded the most information. Chemical shift reagent studies of methylcis-9,10-epoxystearate and methyl erythro-9,10-dihydroxystearate were decidedly inferior. The series of complementary interpretive techniques previously developed during chemical shift reagent studies of monofunctional fatty esters and model polyfunctional fatty esters were found to be applicable in the current study. However, to avoid ambiguity in several proton assignments, supplementary spin decoupling experiments were necessary.     

NMR chemical shift reagents in structural determination of lipid derivatives: II. Methyl petroselinate and methyl oleate

Whentris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octaneodionato)europium (III)—Eu(fod)₃—forms a complex with a sufficiently basic functional group in a donor molecule, the change in the magnetic environment of protons near the coordination site causes their nuclear magnetic resonance (NMR) signals to shift to different positions. Consequently Eu(fod)₃ and other compounds that similarly affect NMR signals have been designated chemical shift reagents (csr). Because of their ability to shift proton signals, csr substantially increase the amount of structural information that can be obtained from NMR spectroscopy, frequently converting complicated splitting patterns into first-order spectra. Some generally useful experimental and interpretive csr techniques are described here using methyl petroselinate and methyl oleate as examples. Csr studies of methyl petroselinate reveal that the position of the double bond is at C-6, and that there is no chain substitution or branching before C-9. Csr studies of methyl oleate reveal that the position of the double bond is at or beyond C-9, and that there is no chain substitution or branching before C-6. Some suggestions are presented for expanding the amount of structural information that can be obtained by csr studies of unsaturated lipid derivatives. Presented in part at AOCS Meeting, Atlantic City, October, 1971.     

Esters of hydroxystearic acids as primary low-temperature plasticizers for a vinyl chloride—Vinyl acetate copolymer

Summary Thirty-one acyloxy or aryloxy esters prepared from hydroxystearic acids have been evaluated as plasticizers for a vinyl chloride-vinyl acetate copolymer (95∶5). Many of them were found to be primary plasticizers, having outstanding low-temperature performance when employed at the 35% level. Formulations with these compounds compared quite favorably in tensile properties with those containing the di-2-ethylhexyl esters of phthalic, sebacic, azelaic, and adipic acids. Volatility losses were similar to those of the four di-2-ethylhexyl esters. The loss of plasticizer through migration was equal to or less than that from compositions containing the esters of sebacic, azelaic, and adipic acids but was greater than that of the phthalate ester. A mechanistic scheme of plasticizer-polymer interaction has been presented, proposing that the rate of diffusion of plasticizer through the polymer mass is a controlling factor in both good low-temperature performance and the resulting high migration losses. Methyl esters, some aromatic esters, and esters containing three or more polar centers have improved permanence but show a more rapid change in torsional modulus as the temperature is lowered during the determination of the Clash-Berg stiffening temperature. Eastern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

EXTERNAL FLUID HEATING OF A POROUS ED

This work deals with the thermal analysis of externally heated porous beds of finite length. A one dimensional model was developed that includes conduction and storage in both the fluid and bed, convective exchange between the fluid and bed, and the effect of adsorption/desorption in the bed. This model results in two coupled differential equations for the fluid and bed temperatures as functions of four independent dimensionless parameters. These equations were solved numerically using finite difference approximations. A truncation error analysis was carried out to maintain an accurate solution. The method of normalization is such that the results of this analysis are of use in bed design when the breakthrough characteristics in finite length beds are of interest. A method to measure bed thermal performance is defined and a means to optimize bed thermal performance is presented. An experiment was conducted to validate the numerically obtained results. A comparison of numerical to experimental results is presented     

Synthesis and Microstructure of Highly Oriented Lead Titanate Thin Films Prepared by a Sol-Gel Method

Thin films of PbTiO₃ were deposited on fused silica, resistor-grade alumina, and single-crystal (100) MgO by a sol–gel processing method. Whereas the films deposited on silica and alumina substrates were randomly oriented and polycrystalline, highly {100} oriented PbTiO₃ films were grown on the MgO single crystals. The perovskite-type structure was observed with films deposited on the single-crystal MgO and annealed at temperatures as low as 470°C, whereas a pyrochlore-type strcuture was observed with films on fused silica and alumina processed in a similar manner. All films heat-treated at temperatures in excess of 570°C showed significant formation of a second PbTi₃O₇ phase. The films were characterized by electron microscopy and glancing-incidence-angle X-ray diffraction.     

Tissue-type plasminogen activator variants with domain duplications and rearrangements

The interactions between tPA domains that are important forcatalysis are poorly understood. We have probed the functionof interdomain interactions by generating tPA variants in whichdomains are duplicated or rearranged. The proteins were expressedin a transient mammalian expression system and tested in vitrofor their ability to activate plasminogen, induce fibrinolysisand bind to a forming fibrin clot. Duplication of the heavychain domains of tPA produced enzymatically active tPA variants,many of which demonstrated similar in vitro amidolytic and fibrinolyticactivity and similar fibrin affinity to the parent molecule.Zymographic analysis of the domain duplication tPA variantsshowed one major active species for each variant. Selectionof the residues duplicated and the interdomain spacing werefound to be critical considerations in the design of tPA variantswith duplicated domains. We also rearranged the domains of tPAsuch that kringle 1 replaced the second kringle domain and viceversa. An analysis of these variants indicates that the firstkringle domain can confer fibrin affinity to a tPA variant andfunction in place of kringle 2. Therefore, in wild-type tPA,the functions of kringle 1 and kringle 2 must be dependent partiallyon their orientation within the heavy chain of the protein.The functional autonomy of the heavy and light chains of tPAis demonstrated by the activity of a tPA variant in which theorder of the heavy and light chains was reversed.     

EXPERIMENTAL STUDIES OF NUCLEATION PHENOMENA WITHIN THERMAL BOUNDARY LAYERS—INFLUENCE ON CHEMICAL VAPOR DEPOSITION RATE PROCESSES

In carrying out partial vapor condensations using actively cooled surfaces it is known that 'mist' formation can occur within thermal boundary layers (Rosner and Epstein, 1968), dramatically modifying total deposition fluxes. Using a combination of flash-evaporation (Rosner and Liang, 1986) and laser probing techniques, we report new experimental results on binary alkali salt (K₂SO₄ + Na₂SO₄) deposition from combustion gases showing that the deposition rate of potassium sulfate first increases with the addition of sodium sulfate until the concentration of Na₂SO₄ reaches a (target surface temperature dependent) 'threshold' value. Further increases in the concentration of Na₂SO₄ dramatically decrease the total deposition rate of K₂SO₄, implying that potassium sulfate-containing microdroplets are formed within the thermal boundary layer, which, despite their thermophoretic drift toward the target, are not collected as effectively as the 'parent' K₂SO₄-vapor species. Laser light scattering measurements clearly reveal that suspended particles exist near the deposition surface under these conditions. Our experimental results on mass transfer rate and light scattering are consistent with those predicted using laminar boundary layer theory (Castillo and Rosner, 1989b) coupling both binary salt vapor deposition with particle vapor scavenging and deposition. Comparisons of our observed mist onset conditions (implying critical supersaturations near unity) with those expected using homogeneous nucleation theory suggest that the binary alkali sulfate mist nucleation mechanism is, instead, heterogeneous, even in our relatively 'clean' combustion products. Because of the; well-known vapor pressure reduction phenomenon associated here with the formation of non-ideal solutions, binary systems are shown to provide convenient 'vehicles' to investigate BL mist formation onset conditions and CVD-rate consequences without requiring the more extreme surface coolings characteristic of unary condensible vapor systems. An understanding of this dramatic phenomenon, obtained via such laboratory experiments and calculations, will allow its inclusion in future deposition rate calculations of engineering importance.     

Oriented crystallization and mechanical properties of polypropylene nucleated on fibrillated polytetrafluoroethylene scaffolds

It is known that friction deposited polytetrafluoroethylene (PTFE) layers are able to nucleate crystallization of thin films of isotactic polypropylene (iPP). In order to investigate the influence of PTFE on the crystallization behavior and morphology of iPP in bulk, PTFE‐particles of two different sizes in various concentrations were melt‐blended with iPP and subsequently processed by injection molding. For one size of particles, high resolution scanning electron microscopy (HR‐SEM) showed the presence of a PTFE scaffold consisting of highly fibrillated PTFE particles. With X‐ray diffraction (WAXD) pole‐figures, it was evidenced that, after melting and recrystallization of the iPP matrix, a strongly oriented crystallization of iPP on this PTFE scaffold takes place (quiescent crystallization conditions). With WAXD it was also shown that under processing conditions, PTFE acts as a nucleating agent for iPP and that PTFE strongly enhances the formation of processing induced morphologies. Impact and tensile performance of the mixtures were measured. Both the strain energy release rate (G_I) and the E‐modulus were found to increase upon introducing PTFE in iPP. POLYM. ENG. SCI., 45:458–468, 2005. © 2005 Society of Plastics Engineers.