Note on the connectivity of line graphs

Let G be a connected graph with vertex set V(G), edge set E(G), vertex-connectivity κ(G) and edge-connectivity λ(G).A subset S of E(G) is called a restricted edge-cut if G−S is disconnected and each component contains at least two vertices. The restricted edge-connectivity λ₂(G) is the minimum cardinality over all restricted edge-cuts. Clearly λ₂(G)?λ(G)?κ(G).In 1969, Chartrand and Stewart have shown that

     

Identification of desulphoglucosinolates in Brassicaceae by LC/MS/MS: comparison of ESI and atmospheric pressure chemical ionisation-MS

In order to develop a sensitive method for the detection of desulphoglucosinolates by HPLC-MS, the two most common interfaces for HPLC-MS, atmospheric pressure chemical ionisation (APCI) and ESI, were compared. While working with the APCI-interface the evaporation temperature and corona amperage were optimised. In doing so 300 degrees C and 6 muA proved to be most suitable for aliphatic and indole desulphoglucosinolates. The use of formic acid instead of water in the eluent in HPLC-ESI-MS measurements increased the sensitivity for the indole desulphoglucosinolates in the presence of 1 mM formic acid, while the sensitivity for the aliphatic desulphoglucosinolate desulphoglucoraphanin was substantially increased by the presence of 5 mM formic acid. Using an Agilent ion trap, two optimisation procedures for the MS parameters, smart and expert mode, were available. In smart mode the software optimises several parameters automatically, which is much more time efficient than expert mode, in which the optimisation is done manually. It turned out that ESI-MS is most sensitive in smart mode, while for APCI-MS a higher sensitivity could be gained using the expert mode. Comparing both interfaces, APCI-MS was more sensitive than ESI-MS. However, no additional information, in terms of structure determination, was obtained by APCI-MS.     

Synthesis,Characterization and Application of Sucrose Carboxylic Acid Polyesters — A Prototype of Non-Caloric or Surface Active Compounds

Sucrose carboxylic acid polyesters are in dependence of the degree of acylation and fatty acid composition more or less undigestible or emulsifying fat substitutes and functional additives for foods. In this connection the relationships between their molecular parameters and functional properties are discussed. New procedures of the solvent-free synthesis are presented. Furthermore, open biochemical and toxicological problems of pinocytosis and accumulation of intact polyesters in organs and tissue being still under investigations are considered.     

Microstructure and Compression Strength of Novel TRIP‐Steel/Mg‐PSZ Composites

Novel composites on basis of austenitic stainless TRIP‐steel as matrix with reinforcements of Mg‐PSZ are presented. Compact rods were produced by cold isostatic pressing and sintering, square honeycomb samples by the ceramic extrusion technique. The samples are characterized by optical and scanning electron microscopy before and after deformation, showing the microstructure and the deformation‐ induced martensite formation. The mechanical properties of samples with 5 vol% zirconia are superior compared to zirconia‐free samples and composites with higher zirconia contents in terms of bending and compression tests. The honeycomb samples exhibit extraordinary high specific energy absorption in compression.     

Linking Simultaneous In Situ WAXS/SAXS/Raman with Raman/ATR/UV–vis Spectroscopy: Comprehensive Insight into the Synthesis of Molybdate Catalyst Precursors

A new setup is presented which enables simultaneous wide- and small-angle X-ray scattering (WAXS/SAXS) and Raman spectroscopic experiments during the synthesis of Mo-based mixed oxide catalyst precursors at the μ-spot beamline at the Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY). Furthermore, we report about the separate monitoring of the same reactions under comparable conditions by simultaneous combined ATR/UV–vis/Raman spectroscopic measurements. For testing the performance of both experimental setups two syntheses were described comprising the precipitation of metal molybdates by mixing solutions of metal nitrates and ammonium heptamolybdate. Additionally, the effect of H₃PO₄ admixture on precipitation was investigated. The combined evaluation of spectroscopic and WAXS/SAXS data allows the discrimination between different molybdate species appearing in solution and precipitate. Furthermore, these molybdate species could be assigned to separate phases of different crystallinity.     

SDS electrophoresis of legume seed proteins in horizontal ultrathin-layer pore gradient gels

Summary Horizontal SDS electrophoresis of 18 legume seed protein extracts was performed in ultrathin-layer polyacrylamide gels on foil supports. Separation results of the SD S pore gradient electrophoresis (T=4–22.5%) are compared to those of SDS electrophoresis in a constant pore size gel (T=10%). Resolution as well as the sensitivity (0.1 g protein per band) of the ultrathin-layer SDS pore-gradient electrophoresis were extremely high. Because of the very low gel thickness, separation, staining and drying were completed in substantially shorter times than achieved with conventional thick gels. An easy technique for casting ultrathin-layer (360 gm) concave gradient gels for 10 cm separation distance and a width of 25 cm is described. The even distribution of the concave exponential pore-gradient over the whole gel width is demonstrated. Molecular weights of the legume proteins are detected from 5,000 to 110,000 daltons. The protein patterns are genus- and species-specific.

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Horizontale Ultradünnschicht SDS-Gradientengel-Elektrophorese von Leguminosensamenproteinen

Zusammenfassung Die ausgezeichnete Trennschärfe der horizontalen Ultradünnschicht-SDS-Gradienten-gel Elektrophorese wird am Beispiel von Samenproteinen 18 verschiedener Leguminosengattungen, -arten und -sorten gezeigt. Es werden die Trennergebnisse der SDS-Elektrophorese mit Gelgradienten (T=4-22,5%) bzw. mit Gelen konstanter Porengröße (T=10%) verglichen. Das höchste Auslösungsvermögen und die beste Trennschärfe zeigen ultradünne Gradientengele. Die Nachweisempfindlichkeit ist bei allen Ultradünn-schicht-SDS-Elektrophoresen sehr hoch (0,1 g Protein/Bande). Da die auf Folie polymerisierten Gele sehr dünn sind (360 m) kann mit wesentlich verkürzten Trenn-, Färbe-, Entfärbe- und Trocknungszeiten gear-beitet werden. Es wird eine einfache Herstellung ultradünner Polyacrylamidgele mit exponentiellen konkaven Gradienten für die Trenndistanz von 10 cm mit einer Breite von 25 cm beschrieben. Die gerade und gleichmäßige Verteilung des Gradienten über die gesamte Gelbreite wird gezeigt. Mit der beschriebenen Methode werden bei den untersuchten Leguminosen-proteinen Molekulargewichte von 5 000 his 110 000 Dalton gefunden. Die Proteinmuster erweisen sich als gattungs- und artspezifisch.

     

Vicious and virtuous circles of offshoring attitudes and relational behaviours. A configurational study of German IT developers

Prior research has shown that the success of offshoring is affected by relational behaviours of the employees involved in an offshoring collaboration. However, hardly anything is known about the attitudes that onshore colleagues hold towards offshoring, and how such offshoring attitudes affect relational behaviours towards offshore colleagues. We therefore present an interpretivist, qualitative case study that explores the offshoring attitudes of German information technology developers. We found that offshoring attitudes affected relational behaviours towards Indian offshore colleagues, in terms of (1) treating Indian colleagues as fellow team members as opposed to suppliers; (2) spending more or less effort in communication and knowledge transfer; and (3) supporting vs. avoiding the task transfer. These relational behaviours fed back into participants' offshoring attitudes, leading to vicious and virtuous circles. The circles created two contrasting configurations of offshoring attitudes and relational behaviours, driven by opposing forces within the departmental context. Our findings highlight the value of taking a configurational perspective for understanding offshoring success and for identifying drivers that need to be managed in order to achieve favourable configurations. We suggest that future research should further expand the typology of attitude‐behaviour configurations and could apply theories of efficacy, self‐reinforcing spirals and planned behaviour.     

Looking on Heterogeneous Catalytic Systems from Different Perspectives: Multitechnique Approaches as a New Challenge for In Situ Studies

Adapting physico-chemical characterization techniques for in situ studies of real heterogeneous catalysts during conditioning, reaction, and deactivation processes is a research topic of growing importance. Up to now, in most studies only one single in situ technique is applied. However, new trends are focused on using a portfolio of several in situ methods to obtain comprehensive information on structure-reactivity relationships. This review discusses such application examples with the aim to point out the particular benefits that arise from multitechnique approaches for understanding processes like formation of active sites, interaction of those sites with reactant molecules, and catalyst deactivation. Except for Fourier-transform infrared spectroscopy and quasi-in situ X-ray photoelectron spectroscopy, the examples deal mainly with the combined use of bulk techniques such as electron paramagnetic resonance, ultraviolet/visible diffuse reflection spectroscopy, laser-Raman spectroscopy, temperature-programmed spectroscopy, X-ray diffraction, and X-ray absorption spectroscopy. However, although not being surface-sensitive per se, these techniques provide results relevant for the catalyzed reaction. Illustrative case studies comprise the investigation of (i) vanadia-based catalysts during selective oxidation and ammoxidation of toluene and during methanol synthesis, (ii) supported chromium oxides during octane aromatization, (iii) zeolite crystallization and catalysis, and (iv) a Cu/ZnO catalyst during methanol synthesis.     

Morphology and properties of foamed high crystallinity PEEK prepared by high temperature thermally induced phase separation

Polyetheretherketone (PEEK) is a high-performance semi-crystalline thermoplastic polymer with outstanding mechanical properties, high thermal stability, resistance to most common solvents, and good biocompatibility. A high temperature thermally induced phase separation technique was used to produce PEEK foams with controlled foam density from PEEK in 4-phenylphenol (4PPH) solutions. Physical and mechanical properties, foam and bulk density, surface area, and pore morphology of foamed PEEK were characterized and the role of PEEK concentration and cooling rate was investigated. Porous PEEK with densities ranging from 110 to 360 kg/m³ with elastic moduli and crush strength ranging from 13 to 125 MPa and 0.8 to 7 MPa, respectively, was produced.