13C CPMAS NMR investigations of cellulose polymorphs in different pulps

In order to obtain information about the crystallinity and polymorphs of cellulose, and the occurrence of hemicelluloses in pulp fibers, wood cellulose, bacterial cellulose, cotton linters, viscose, and celluloses in different pulps were investigated by solid state ¹³C CPMAS NMR spectroscopy. A mixed softwood kraft pulp and a dissolving-grade pulp were treated under strongly alkaline and acidic conditions and the effect on cellulose crystallinity was studied. The presence of different crystalline polymorphs of cellulose and the amounts of hemicelluloses are considered.     

Mass spectrometric characterization of a series of adenosylated peptides acting as bisubstrate analogs of protein kinases

We are currently developing strategies to synthesize bisubstrate analogs as potential inhibitors of serine and tyrosine protein kinases; several such analogs have been synthesized. The initial target proteins were the cAMP dependent protein kinase (cAPK) and the Ca⁺²/calmodulin dependent protein kinase (CaM kiiase II). These bisubstrate analogs were based on either known peptide substrates such as kemptide, a seven amino acid peptide substrate of cAPK, or on inhibitory peptides such as a seventeen amino acid peptide encompassing the autoinhibitory domain of CaM kinase II. Peptides containing a single phosphoserine group were first synthesized and then adenosine 5′-monophosphate (AMP), adenosine 5′-diphosphate (ADP), or adenosine 5′-triphosphate (ATP) was coupled through the serine phosphate with prior activation by 1,1-carbonyldiimidazole using either a solution or solid phase reaction scheme. In this current study, we report the characterization of the bisubstrate analogs by liquid secondary ionization mass spectrometry (LSIMS), matrix-assisted laser desorption mass spectrometry (MALDI), and tandem mass spectrometry (MS/MS). In the positive-ion mode, the LSIMS spectra of the bisubstrate analogs yielded a series of molecular ions containing mono-, di-, and trivalent cation adducts. Cation adducts were absent in the negative-ion mode where the dominant species were deprotonated molecular ions, [M ? H]^?, making this latter technique more useful for confirming product identity and assessing purity. Analysis of these compounds by MALDI in both the positive- and negative-ion modes yielded molecular ions which also contained metal ion adducts, although they were limited primarily to Fe⁺² adducts. Unlike LSIMS, the MALDI spectra showed no evidence for the elimination of the phosphoadenosine or other structural moieties. When these compounds were subjected to high energy collision-induced dissociation (CID), the dominant fragmentation pathways under positive-ion MS/MS conditions resulted from cleavage of the phosphate linkages to the adenosine moiety with charge retention on the peptide, although a major peak for 5′-deoxyadenosine was also seen at m/z 250. Charge retention in the negative-ion mode was most pronounced for ion fragments containing the highly acidic phosphate moieties and yielded phosphoadenosine related ions, for example, (AMP-H)^?, (AMP-H-H₂O)^?, (ADP-H)^?, etc., as well as ions originating from the phosphate linker such as PO₃ ^?, H₂PO₄ ^?, HP₂O₆ ^?, H₃P₂O₇ ^?, and H₂P₃O₉ ^?. The largest phosphoadenosine ion in the negative-ion CID spectra for each bisubstrate analog, for example, m/z 426 (ADP-H)^?, m/z 506 (ATP-H)^?, or m/z 586 (AP₄-H)^?, indicated that the desired covalent modification had been formed between the phosphoserine and AP_n moieties.     

Past and future impact of electroactive polymers on the electronics sector

A broad review of the field of applications of electroactive polymers, defined as inherently conductive, charged, piezoelectric and pyroelectric, and systems made electroactive by addition of conductive additives, in the field of electronics and microelectronics. Applications mentioned include the use of polymers for electrodes for rechargeable batteries, electret microphones, hydrophones, vidicons, EMI and ESD protection, and conductor and resistor tracks as thick films on printed circuit boards. Future trends as the development of supermolecular assemblies for parallel processing are also highlighted.     

Passive Systems with a Normal Main Operator and Quasi-selfadjoint Systems

Passive systems with and as an input and output space and as a state space are considered in the case that the main operator on the state space is normal. Basic properties are given and a general unitary similarity result involving some spectral theoretic conditions on the main operator is established. A passive system with is said to be quasi-selfadjoint if ran . The subclass of the Schur class is the class formed by all transfer functions of quasi-selfadjoint passive systems. The subclass is characterized and minimal passive quasi-selfadjoint realizations are studied. The connection between the transfer function belonging to the subclass and the Q-function of T is given. Received: December 16, 2007., Accepted: March 4, 2008.     

In situ fabrication of waveguide-compatible glass-embedded silver nanoparticle patterns by masked ion-exchange process

We report a study on the properties of silver nanoparticles formed in glass using a masked silver–sodium ion-exchange technique, a process that has been used to fabricate patterned optical waveguides. Characterizations reveal that spherical nanoparticles with a diameter of 5–10 nm are concentrated below the mask edge at a depth of 50–100 nm from the surface. The amount of nanoparticles and the wavelength of the associated localized surface plasmon resonance can be controlled by the spacing between adjacent mask openings. After gentle etching, the surface morphology of the sample shows well-defined nanoparticle patterns. These closely packed nanoparticles embedded in the glass surface have a potential to be used for high-sensitivity surface enhanced spectroscopy, in a glass waveguide device.     

Nevanlinna Functions,Perturbation Formulas,and Triplets of Hilbert Spaces

Let S be a closed symmetric operator with defect numbers (1,1) in a Hilbert space ?? and let A be a selfadjoint operator extension of S in ??. Then S is necessarily a graph restriction of A and the selfadjoint extensions of S can be considered as graph perturbations of A, cf. [8]. Only when S is not densely defined and, in particular, when S is bounded, 5 is given by a domain restriction of A and the graph perturbations reduce to rank one perturbations in the sense of [23]. This happens precisely when the Q - function of S and A belongs to the subclass No of Nevanlinna functions. In this paper we show that by going beyond the Hilbert space ?? the graph perturbations can be interpreted as compressions of rank one perturbations. We present two points of view: either the Hilbert space ?? is given a one-dimensional extension, or the use of Hilbert space triplets associated with A is invoked. If the Q - function of S and A belongs to the subclass N₁ of Nevanlinna functions, then it is convenient to describe the selfadjoint extensions of S including its generalized Friedrichs extension (see [6]) by interpolating the original triplet, cf. [5]. For the case when A is semibounded, see also [4]. We prove some invariance properties, which imply that such an interpolation is independent of the (nonexceptional) extension.     

Double diffusive convection in the diffusive regime

Numerical solutions to convection of a fluid which is heated, and to which salt is introduced from the bottom, have been obtained. Although different in boundary conditions from the conditions in the study of Huppert and Moore, qualitatively the flow investigated here has many features the same as theirs. The differences are discussed and solutions are given for two fluids whose Prandtl numbers are 1 and 7 and ratio of molecular and thermal diffusivities is 0.1. The fields of temperature and salinity, and the stream patterns are shown in contour plots. The saline and thermal Nusselt numbers are given as functions of the thermal Rayleigh number.Nomenclature A aspect ratio of the enclosure - g gravitational acceleration - H the height of the enclosure - k _S molecular diffusivity of salt - k _T molecular diffusivity of heat - N _S averaged saline Nusselt number - N _T averaged thermal Nusselt number - P transported variable of temperature, salinity, or vorticity - p pressure above its hydrostatic value - Pr Prandtl number - velocity vector - R _S saline Rayleigh number - R _T thermal Rayleigh number - S salinity - S slainity difference between the top and the bottom - S ₀ salinity at the top surface - S _r salinity at the reference state=S₀+S/2 - T temperature - T temperature difference between the top and and the bottom - T ₀ temperature at the top surface - T _r temperature at the reference state=T₀+T/2 - t time - u velocity component in the horizontal direction - transport velocity - v velocity component in the vertical direction - W the width of the enclosure - x horizontal coordinate - x mesh size in the horizontal direction - y vertical coordinate Greek Letters coefficient of thermal expansion - coefficient of volumetric expansion produced by salt - kinematic viscosity - ratio of diffusivities - vorticity - density - _r density at the reference state - density difference between the top and the bottom - streamfunction