Some results concerning Lp(μ)-spaces

It is proved that L^p(μ) does not have an unconditional basis if the cardinality of L^p(μ) is sufficiently large and μ is a finite measure. It is also shown that L^p(μ) has a weaker kind of basis for arbitrary μ and 1 < p < ∞. A new truncation lemma concerning sequences in L^p equivalent to the usual l^p-basis is given. This lemma is used in solving the problem of when l^p(Γ) imbeds in L^r(μ) for uncountable sets Γ and finite measures μ. It may also be used to give a nonprobabilistic proof of the fact (due to Schwartz-Kwapien) that there exist non-q-absolutely summing operators from L^∞to L^qfor 2 < q < ∞. It is again used in proving that basic sequences in L^p equivalent to the usual l^p-basis admit subsequences with a complemented linear span. Other applications of the techniques introduced are also given.     

Index theory of geometric Fredholm operators on varieties with isolated singularities

It sometimes happens that geometric elliptic differential operators on a noncompact Riemannian manifold are Fredholm. The smooth parts of singular algebraic varieties provide examples of complete and incomplete manifolds where this can happen. The indices of such operators often provide topological or geometric information about the singular variety. This paper shows that the operators of the title represent K homology elements and solves the index problem for these operators by exhibiting equivalent K homology cycles in topological form.This material is based upon work supported by the National Science Foundation under Grant No. DMS-8501513.     

Characterisation of bacterial cellulose from diverse <Emphasis Type="Italic">Komagataeibacter</Emphasis> strains and their application to construct plant cell wall analogues

This study investigated cellulose production and microstructure variation from six Komagataeibacter strains (ATCC 53524, ATCC 10245, ATCC 23769, ATCC 700178, NBRC 13693 and KTH 5655). Strain KTH 5655 produced the highest cellulose yields (10.39 g/l) after 9 days cultivation. Nuclear magnetic resonance spectroscopy and X-ray diffraction revealed that strain ATCC 23769 synthesised cellulose with the lowest crystallinity and decreased ratio of Iα/Iβ allomorph, whilst strain KTH 5655 produced a relatively ordered cellulose structure. However, the average widths of cellulose ribbons were similar (30–50 nm) for all types of cellulose. Phylogenetic analysis of the 16S rRNA gene indicated that these strains shared a high level of genetic similarity (ranging from 88 to 98%). All strains were used to produce cellulose in the presence of arabinoxylan or xyloglucan as simplified cell wall analogues. Our results provide guidance for the selection of cellulose-producing strains for specific biotechnological and research applications.     

Atmospheric Pressure Ionization Using a High Voltage Target Compared to Electrospray Ionization

A new atmospheric pressure ionization (API) source, viz. UniSpray, was evaluated for mass spectrometry (MS) analysis of pharmaceutical compounds by head-to-head comparison with electrospray ionization (ESI) on the same high-resolution MS system. The atmospheric pressure ionization source is composed of a grounded nebulizer spraying onto a high voltage, cylindrical stainless steel target. Molecules are ionized in a similar fashion to electrospray ionization, predominantly producing protonated or deprotonated species. Adduct formation (e.g., proton and sodium adducts) and in-source fragmentation is shown to be almost identical between the two sources. The performance of the new API source was compared with electrospray by infusion of a mix of 22 pharmaceutical compounds with a wide variety of functional groups and physico-chemical properties (molecular weight, logP, and pKa) in more than 100 different conditions (mobile phase strength, solvents, pH, and flow rate). The new API source shows an intensity gain of a factor 2.2 compared with ESI considering all conditions on all compounds tested. Finally, some hypotheses on the ionization mechanism, similarities, and differences with ESI, are discussed.

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One drop chemical derivatization – DESI‐MS analysis for metabolite structure identification

Structural elucidation of metabolites is an important part during the discovery and development process of new pharmaceutical drugs. Liquid Chromatography (LC) in combination with Mass Spectrometry (MS) is usually the technique of choice for structural identification but cannot always provide precise structural identification of the studied metabolite (e.g. site of hydroxylation and site of glucuronidation). In order to identify those metabolites, different approaches are used combined with MS data including nuclear magnetic resonance, hydrogen/deuterium exchange and chemical derivatization followed by LC‐MS. Those techniques are often time‐consuming and/or require extra sample pre‐treatment. In this paper, a fast and easy to set up tool using desorption electrospray ionization–MS for metabolite identification is presented. In the developed method, analytes in solution are simply dried on a glass plate with printed Teflon spots and then a single drop of derivatization mixture is added. Once the spot is dried, the derivatized compound is analyzed. Six classic chemical derivatizations were adjusted to work as a one drop reaction and applied on a list of compounds with relevant functional groups. Subsequently, two successive reactions on a single spot of amoxicillin were tested and the methodology described was successfully applied on an in vitro incubated alprazolam metabolite. All reactions and analyses were performed within an hour and gave useful structural information by derivatizing functional groups, making the method a time‐saving and efficient tool for metabolite identification if used in addition or in some cases as an alternative to common methods. Copyright © 2015 John Wiley & Sons, Ltd.     

High-efficiency high performance liquid chromatographic analysis of red wine anthocyanins

The analysis of anthocyanins in natural products is of significant relevance in recent times due to the recognised health benefits associated with their consumption. In red grapes and wines in particular, anthocyanins are known to contribute important properties to the sensory (colour and taste), anti-oxidant- and ageing characteristics. However, the detailed investigation of the alteration of these compounds during wine ageing is hampered by the challenges associated with the separation of grape-derived anthocyanins and their derived products. High performance liquid chromatography (HPLC) is primarily used for this purpose, often in combination with mass spectrometric (MS) detection, although conventional HPLC methods provide incomplete resolution. We have previously demonstrated how on-column inter-conversion reactions are responsible for poor chromatographic efficiency in the HPLC analysis of anthocyanins, and how an increase in temperature and decrease in particle size may improve the chromatographic performance. In the current contribution an experimental configuration for the high efficiency analysis of anthocyanins is derived using the kinetic plot method (KPM). Further, it is shown how analysis under optimal conditions, in combination with MS detection, delivers much improved separation and identification of red wine anthocyanins and their derived products. This improved analytical performance holds promise for the in-depth investigation of these influential compounds in wine during ageing.     

On a theorem of J. L. Krivine concerning block finite representability of lp in general Banach spaces

A simplified proof and generalizations are given for the following remarkable theorem of J. L. Krivine: Let (x_j) be a sequence in a Banach space with infinite-dimensional linear span. Then either there is a 1 ? p < ∞ so that l^p is block finitely represented in (x_j) or c₀ is block finitely represented in some permutation of (x_j).     

Variable-Temperature and Variable-Pressure 17O-NMR Study of Water Exchange of Hexaaquaaluminium(III)

The transverse relaxation rate of H₂O in Al(H₂O) has been measured as a function of temperature (255 to 417 K) and pressure (up to 220 MPa) using the ¹⁷O-NMR line-broadening technique, in the presence of Mn(II) as a relaxation agent. At high temperatures the relaxation rate is governed by chemical exchange with bulk H₂O, whereas at low temperatures quadrupolar relaxation is prevailing. Low-temperature fast-injection ¹⁷O-NMR was used to extend the accessible kinetic domain. The samples studied contained Al³⁺ (0.5 m), Mn²⁺ (0.2–0.5 m), H ⁺ (0.2–3.1 m) and ¹⁷O-enriched (20–40%) H₂O. Non-coordinating perchlorate was used as counter ion. The following H₂O exchange parameters were obtained: k = (1.29 ± 0.04) s⁻¹, ΔH* = (84.7 ± 0.3) kJ mol⁻¹, ΔS* = +(41.6 ± 0.9) J K ⁻¹ mol⁻¹, and ΔV = +(5.7 ± 0.2) cm³ mol⁻¹, indicating a dissociative interchange, I_d, mechanism. These results of H₂O exchange on Al(H₂O) are discussed together with the available complex-formation rate data and permit also the assignment of I_d mechanisms to these latter reactions.     

Electronic properties of Ru(II) complexes bound to a bisphenolate bridge with low lying pi* orbitals

The synthesis and a detailed investigation into the electronic properties of mononuclear and dinuclear Ru(II) complexes of the ligand bis(2-hydroxyphenyl)-2,5-dihydropyrazine (H(2)BHD) is described. In these complexes the Ru(II) moieties are bound through O,N coordination to an anionic phenolate and the pyrazine bridge. Relatively few reports are available on the dinuclear complexes bridged across a phenolate and this study provides an opportunity to examine the impact of reduced oxygen donor ligands on metal-metal communication. The results presented here reveal some very unusual behavior whereby the apparent location of the LUMO changes between the mononuclear and dinuclear complexes. The lowest energy optical transition appears to involve the peripheral bipyridine ligand as acceptor in the mononuclear complex, whereas this ligand is not involved in the lowest energy optical transition in the dinuclear complex. The origin of this difference is not clear, however, significant changes in the electronic properties of the mononuclear complex are observed on coordination of the second metal, reflected in significant alterations in the electrochemistry of the bridge and metals as well as changes in the optical spectroscopy. The BHD(2-) bridge is shown to support weakly coupled class II behavior according to the Robin and Day classification, reflected in a K(c) of 335.     

Kinetic plot method as a tool to design coupled column systems producing 100,000 theoretical plates in the shortest possible time

The present paper reports on the possibility to use the kinetic plot method (KPM) to select and design the best possible system to achieve a given number (100,000) of theoretical plates for a pharmaceutical test mixture, using the information obtained from a series of single column performance measurements of sub-2microm and supra-2microm porous shell particles conducted at three different temperatures and using mixtures of acetonitrile and 0.1% formic acid in water as the mobile phase. Because the KPM involves an extrapolation to different column lengths, the quality of the design was subsequently verified by coupling several columns to achieve the optimal total column length and run the actual analysis at the calculated optimal flow rate. The prediction error was generally better than 10%, with a slightly better prediction for t(0) and N than for the retention time t(R). The sub-2microm and the porous shell particle coupled column systems achieve the 100,000 plates about equally fast, despite the fact that the former were used at 1000bar and the latter only at 600bar. The high temperature operation (80 degrees C) yielded the fastest separation in both cases, allowing to reach 100,000 plates for a component eluting at k'=2.5 in only about 15min.