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First-principles calculations for KH 2 PO 4 (KDP) show that hydrogen off-center (OC) ordering in the ferroelectric phase is accompanied by electronic charge delocalization from the acceptor and localization at the donor oxygen within the O-H···O bonds. This induces P atoms off-centering in the PO 4 tetrahedrons and pairing with K + ions along the tetragonal axis, thus developing macroscopic polarization. Centered H are collectivelly unstable. However, if the protons are centered, the P and K atoms are stable in their centered positions. In addition, off-centering of a single proton is not energetically favorable. Only correlated proton motions, involving also displacements of heavier atoms, exhibit significant double wells, thus questioning the role of tunneling in isotope effects.

Abstract: The results of experiment on the influence of a direct current and a low-frequency alternating current, as well as a magnetic field, on the microwave-range conductivity σ MW of Ln0.7Pb0.3MnO3 single crystals with giant magnetoresistance are presented. The greatest sensitivity of the samples toward the effects of a current is observed in the temperature range corresponding to the dc magnetoresistance maximum. The response signal of a sample in the microwave range to the effects of an alternating current of a low frequency f 0 has a nonlinear character. As f 0 is varied in a magnetic field, the amplitude of the response signal varies with the appearance of resonance peaks. The results obtained are interpreted within an approach based on the coexistence of two phases having different conductivities in the doped manganite crystals. This two-phase interpretation is supported by data from magneticresonance investigations, which demonstrate the existence of two magnetic phases over a broad temperature range in Ln0.7Pb0.3MnO3 single crystals.

Purified flagellar filaments isolated from six methanogens were composed of multiple flagellins. Two flagellins were present in Methanococcus deltae (Mr=34000 and 32000), Methanoculleus marisnigri (Mr=31000 and 25500) and Methanococcus jannaschii (Mr=31000 and 27500), three in Methanothermus fervidus (Mr=34000, 25000 and 24000) and four or more in both Methanococcus vanniellii and Methanococcus maripaludis (Mrranging from 27500 to 32000). The flagellins of M. fervidus and M. deltae reacted positively with glycoprotein-specific stains. The flagellins of M. deltae, M. maripaludis and M. vannielii were closely related to those of M. voltae based on cross-reactivity with antisera raised against M. voltae flagellins and homology with flagellin-specific oligonucleotide probes to the N-terminus and leader peptide of M. voltae flagellins. Similarities appear to exist among the flagellins of M. fervidus, M. marisnigri and Halobacterium halobium based on cross-reactivity with antisera produced against the flagella of Methanospirillum hungatei JF1. The N-termini of the flagellins from the mesophilic Methanococcus spp. and M. marisnigri show homology with the N-termini of other archaebacterial flagellins. These N-termini may undergo a modification involving removal of a leader peptide.

The dynamics of electrical explosion of tungsten wires under water in microsecond times was studied. A new optical method for temperature measurement has been developed. For tungsten, uniform heating took place at 1011

The effect of secondary recrystallization and coarsening of the structure in annealing of hot pressed manganese-zinc ferrites may be used for substantially increasing their initial magnetic permeability.

The ultrastructure and chemical composition of the cell wall of the marine archaebacterium Methanococcus voltae were studied by negative-staining and freeze-etch electron microscopy and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. M. voltae possesses a single regularly structured (RS) protein layer external to the plasma membrane. Freeze-etch preparations of cells indicated that the protein subunits are hexagonally arranged with a center-to-center spacing of approximately 10 nm. The extracted RS protein had a molecular weight of 76,000. It was present on envelopes prepared by shearing in a French press, osmotic lysis, or sonication, as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. NaCl was not required for attachment of the RS protein to the underlying plasma membrane. The hexagonal array could be demonstrated by platinum shadowing and freeze-etching of envelopes, but negative staining in the abscence of NaCl failed to stabilize the array. The RS protein could be solubilized by urea, guanidine hydrochloride, dithiothreitol, and several detergents, including Nonidet P-40, Triton X-100, and Tween 20. However, the most specific release of the wall protein from envelopes occurred after a heat treatment in HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) buffer at 50 to 60 degrees C.

We determined that paracrystalline protein surface arrays (S layers) protected gram-negative eubacteria from predation by Bdellovibrio bacteriovorus. Aquaspirillum serpens VHA and MW5 and Aquaspirillum sinuosum were resistant to predation by B. bacteriovorus 6-5-S when fully covered by their S layers. The S layer of Aeromonas salmonicida A449 protected the cells from predication by B. bacteriovorus 109J. A predacious, plaque-forming vibrio that lysed an S-layer- variant of Caulobacter crescentus but was not predacious on the parental strain which possessed an S layer was isolated from raw sewage. Since S layers are stable components of many bacterial surfaces in nature, they can provide this protective function in both aquatic and terrestrial habitats where Bdellovibrio spp. are found.

In high (45 mM)-phosphate medium, Methanospirillum hungatei strains GP1 and JF1 grew as very long, nonmotile chains of cells that did not possess flagella. However, growth in lower (3 or 30 mM)-phosphate medium resulted in the production of mostly single cells and short chains that were motile by means of two polar tufts of flagella, which transected the multilayered terminal plug of the cell. Electron microscopy of negatively stained whole mounts revealed a flagellar filament diameter of approximately 10 nm. Flagellar filaments were isolated from either culture fluid or concentrated cell suspensions that were subjected to shearing. Flagellar filaments were sensitive to treatment with both Triton X-100 and Triton X-114 at concentrations as low as 0.1% (vol/vol). The filaments of both strains were composed of two flagellins of Mr 24,000 and 25,000. However, variations in trace element composition of the medium resulted in the production of a third flagellin in strain JF1. This additional flagellin appeared as a ladderlike smear on sodium dodecyl sulfate-polyacylamide gels with a center of intensity of Mr 35,000 and cross-reacted with antisera produced from filaments containing only the Mr-24,000 and -25,000 flagellins. On sodium dodecyl sulfate-polyacrylamide gels, all flagellins stained by the thymol-sulfuric acid and Alcian blue methods, suggesting that they were glycosylated. This was further supported by chemical deglycosylation of the strain JF1 flagellins, which resulted in a reduction in their apparent molecular weight on sodium dodecyl sulfate-polyacylamide gels. Heterologous reactions to sera raised against the flagella from each strain were limited to the Mr-24,000 flagellins.

The flagella of Methanococcus voltae were isolated by using three procedures. Initially, cells were sheared to release the filaments, which were purified by differential centrifugation and banding in KBr gradients. Flagella were also prepared by solubilization of cells with 1% (vol/vol) Triton X-100 and purified as described above. Both of these techniques resulted in variable recovery and poor yield of flagellar filaments. Purification of intact flagella (filament, hook, and basal body) was achieved by using phase transition separation with Triton X-114. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified flagella revealed two major proteins, with molecular weights of 33,000 and 31,000. This result indicates the likely presence of two flagellins. The filament had a diameter of 13 nm. The basal structure consisted of a small knob, while a slight thickening of the filament immediately adjacent to this area was the only evidence of a hook region. Flagella from three other Methanococcus species were isolated by this technique and found to have the same ultrastructure as flagella from M. voltae. Isolation of flagella from three eubacteria and another methanogen (Methanospirillum hungatei [M. hungatii]) by the phase separation technique indicated that the detergent treatment did not affect the structure of basal bodies. Intact ring structures and well-differentiated hook regions were apparent in each of these flagellar preparations.

Methanospirillum hungateistrains GP1 and JF1 when cultivated at 37°C in JMA medium grew as motile single cells or short chains of cells (typically 10–30 μm long). When M. hungateiwas grown in low Ca2+concentrations or with the divalent cation chelator EDTA, the organism grew as long non-flagellated filaments (up to 900 μm long). The two strains had different thresholds of calcium concentrations for long filament formation (<0.25 mM for GP1 and <0.15 mM for JF1) as well as different minimal Ca2+requirements for growth. Both strains produced long, almost straight, filaments at Ca2+concentrations near the minimum required for growth. At suboptimal growth temperatures the organisms still grew as short filaments but no longer possessed flagella. Western blot analysis indicated that flagellin monomer was present in cultures of long non-flagellated filaments and short non-flagellated cultures grown at suboptimal temperatures. The amount of flagellin present appeared to be equal in both non-flagellated and flagellated cultures. When cells were grown as long non-flagellated filaments and switched to growth conditions inducing short, flagellated forms, flagella were first observed at 2.5 h after this switch.

The Triton X-100-insoluble wall fraction of Aquaspirillum serpens VHA contained three major proteins: the regularly structured (RS) superficial protein (molecular weight 140,000) and two peptidoglycan-associated proteins (molecular weights, 32,000 and 33,000). The molecular arrangement and interactions of the outer membrane and RS proteins were examined with the use of bifunctional cross-linking reagents. The peptidoglycan-associated and RS proteins were not readily cross-linked in either homo- or heteropolymers. This suggests that the free amino groups are not suitably disposed for cross-linking. Some high-molecular-weight multimers of the RS protein were produced, but the subunit structure of the RS array was not stabilized by cross-linking. The peptidoglycan-associated proteins were cross-linked to high-molecular-weight multimers, but no dimers or trimers were produced. This result suggests that these proteins exist in the outer membrane as multimers larger than trimers.

The aim of this study was to assess influence of different variants of combined treatment of hypertension, including with type 2 diabetes (T2D), with application of angiotensin receptor blocker (ARB) olmesartan or angiotensin-converting enzyme (ACE) inhibitor ramipril on apelin blood levels.

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The aim of the study was to investigate the peculiarities of the changes angiopoetin - 2 (Ang-2) of blood levels in patients with essential hypertension (EH).