Eigenvalues and eigenfunctions of discontinuous Sturm--Liouville problems with eigenparameter-dependent boundary conditions

We extend some fundamental spectral properties of classic regular Sturm--Liouville problems to discontinuous boundary-value problems with eigenvalue-dependent boundary conditions. We suggest a new approach for investigation of such type discontinuous problems.     

Diastereoselective O-Vinylation of Phenols using DMAD under Mild Reaction Conditions

An efficient and straightforward pyridine-catalyzed method allowing selective O-vinylation of phenols with DMAD is reported. The reaction is diastereoselective and leads exclusively to (Z)-configuration in high yields.     

Application of an ion mobility detector in radiation stimulated plasma chemistry

Fast electrons emitted by a beta radiation source produce ion pairs between a two eletrode arrangement full with argon or nitrogen at ambient pressure. Ions created there were identified with the help of an ion mobility spectrometer. The production of reactive species by field accelerated electrons was studied in argon.     

Protein‐ and homo poly(amino acid)‐based hydrogels with super‐swelling properties

The use of super‐swelling polymers is steadily increasing and the applications in industry are continuing to grow. With the authorization of the superabsorbents in food packaging by the Food and Drug Administration recently, demand may soon take off in the market. However, the increase in prices of petroleum products in recent years may be a drawback for these acrylic‐based materials. Thus, there is now a need to develop natural‐based super‐swelling hydrogels which are more economical and environment friendly. In addition, the super‐swelling gels are promising novel functions in the biomedical and pharmaceutical applications. This review is aimed to highlight research and trends in protein‐ and homo poly(amino acid)‐based super‐swelling hydrogels. Thus, the proteinaceous hydrogels, including chemically modified soy‐, fish‐ and collagen‐based proteins, are discussed. The protein‐polysaccharide, protein‐synthetics, and the inorganic composites are also investigated as hybrid materials. Finally, the super‐swelling hydrogels based on homo polypeptides, i.e. poly(aspartic acid), poly(glutamic acid), and poly(ε‐L‐lysine) are reviewed. Copyright © 2009 John Wiley & Sons, Ltd.     

Linseed oil‐based reactive diluents preparation to improve tetra‐functional epoxy resin properties

Two kinds of bio‐resourced reactive diluents have been synthesized from linseed oil. The prepared epoxidized linseed oil (ELO) and the cyclocarbonated linseed oil (CLO) were separately blended with a petroleum‐based tetra‐functional epoxy resin (TGDDM) to improve its processability and to overcome the brittleness of the thermoset network therefrom. The linseed oil modifications were spectrally established, and processability improvement of the resin blends was rheologically confirmed. The curing of samples was studied by differential scanning calorimetry, and their mechanical properties (ie, tensile, flexural, fracture toughness, and adhesion) were investigated as well. Scanning electron microscopy images were obtained to reconfirm the toughness improvement of the modified thermosets. In contrast of the epoxidized soybean oil (ie, the most conventionally studied bio‐based reactive diluent), ELO and CLO had no negative effects on the thermoset material characteristics. They improved properties such as tensile strength (up to 43.2 MPa), fracture toughness (1.1 MPa m^1/2), and peel‐adhesion strength (4.5 N/25 mm). It was concluded that ELO and CLO were efficient reactive diluents to be used in formulations of polymer composites, surface coatings, and structural adhesives based on epoxy resins.     

Investigations about triggering of coaxial multichannel pseudosparkswitches

A fundamental problem of pseudospark switches is erosion in the borehole area. One way to reduce erosion is to distribute the current to several discharge channels. Essential for multichannel operation is a reliable ignition of all these channels. The aim of this work was to find out the requirements for a trigger for multichannel pseudospark switches and to develop a suitable trigger device. The investigations were made with a three channel pseudospark switch. The developed trigger is a pulsed hollow cathode discharge with a 3 mA dc-preionization. A trigger voltage of 4 kV results in a current of about 6 A in the hollow cathode of the trigger-section. This hollow cathode discharge causes a trigger current into the hollow cathodes of the pseudospark chambers. The trigger current which is necessary to ignite an equally distributed discharge has to be at least 3 mA into each main switch hollow cathode. A jitter of 2 ns was achieved for the coaxial multichannel pseudospark switch     

Measurement and calculation of the two-dimensional backscattering Mueller matrix of a turbid medium: errata

In our recent Letter,(1) several typographical errors were present. On p. 487, in Fig. 2, the equations for the following Mueller matrix elements should read as S(14) = (RO - LO), S(22) = (HH + VV) - (HV + VH), S(23) = (PH + MV) - (PV + MH), S(24) = (RH + LV) - (RV + LH), S(32) = (HP + VM) - (HM + VP), S(33) = (PP + MM) - (PM + MP), S(34) = (RP + LM) - (RM + LP), S(41) = (OR + OL), S(42) = (HR + VL) - (HL + VR), S(43) = (PR + ML) - (PL + MR), and S(44) = (RR + LL) - (RL + LR). Also on p. 487, in the left-hand column, line 10 from the top should read as follows: mfp? = 1/[mua + mus(1 - g)], was 0.957 cm.     

ON ALGEBRAIC VOLUME DENSITY PROPERTY

A smooth affine algebraic variety X equipped with an algebraic volume form ω has the algebraic volume density property (AVDP) if the Lie algebra generated by complete algebraic vector fields of ω-divergence zero coincides with the space of all algebraic vector fields of ω-divergence zero. We develop an effective criterion of verifying whether a given X has AVDP. As an application of this method we establish AVDP for any homogeneous space X = G/R that admits a G-invariant algebraic volume form where G is a linear algebraic group and R is a closed reductive subgroup of G.     

Zur alkalischen Verseifung der Diacetylweinsäure und ihres Methylesters

Zusammenfassung Es wurde die alkalische Verseifungsgeschwindigkeit der Diacetylweinsäure und ihres Methylesters untersucht.Im Methylester verseifen die Methyle mit einer weit größeren Geschwindigkeit als die Acetyle. Das Konstantenverhältnis der stufenweisen Methylverseifung ist ungefähr 21.Das Konstantenverhältnis der stufenweisen Acetylverseifung in der Diacetylweinsäure ist rund 3·51.     

β-Eucryptite by a Sol-Gel Route

-Eucryptite solid solution (LAS) Li2O : Al 2O3 : 3SiO2(113) was prepared via a sol-gel route. Complex solutions of lithium or aluminum salts in ethanol/water mixtures were catalysed by inorganic acids (catalyst/alkoxide ratio 0.1). Different ratios of H2SO4 catalyst were also used.TGA showed that the maximum % yield of LAS 113 occurred using H2SO4 catalyst. Above 400°C exothermic peaks occurred in DSC followed by the glass transition. XRD and IR showed a high crystallinity of -eucryptite solid solution using all acids at the 0.1 ratio with the highest crystallinity for the 0.05 H2SO4 ratio. SEM revealed similar grain sizes in spite of higher acid concentrations. XRD data indicated a change to a tetragonal modification with higher catalyst ratio.