Properties Of Other Members Research Articles

Determination of single-crystal elastic moduli of LiREF4 (RE = Y, Gd, and Tb) by resonant ultrasound spectroscopy

The tetragonal fluoro-scheelite LiREF4 compounds (RE=rareearth) have been shown to exhibit a variety of useful optical and magnetic properties. While LiYF4 has been widely studied, many of the fundamental thermodynamic properties of other members of this family remain unknown. Here, we report the complete elastic tensors (Cij) of single-crystalline LiYF4, LiTbF4, and LiGdF4 using resonant ultrasound spectroscopy and density functional theory (DFT). We compare the results for LiYF4 with prior experimental results using time-of-flight ultrasound methods. This is the first report, however, of the experimental elastic tensors of LiTbF4 and LiGdF4. The present results point to a softening of the elastic moduli of the LiREF4 system when Y is replaced by the larger ionic radius of Tb or Gd. Furthermore, we find that just 0.3% doping with Nd on the Y site also leads to a slight softening of the moduli. The variation of the elastic moduli as a function of temperature up to 216°C was also measured. A nearly linear softening of all seven independent elastic moduli was observed with increasing temperature. Phonon dispersions and phonon density of states obtained by DFT support the experimental finding of a significantly higher sound velocity due to lighter Y atoms in LiYF4, as compared to heavier LiTbF4 and LiGdF4.

Motel Builders of the Modern West

Motel Builders of the Modern West

Enhanced magnetic properties of YBa2Cu3O7−δ bulk superconductors with tailored structure by a novel seeding assembly

YBa2Cu3O7−δ (YBCO) bulk superconductors are regarded as the most promising alternatives for conventional permanent magnets as they provide high field trapping capacity at low temperatures. However, for further improving their superconducting properties, it remains a significant challenge to enlarge the c growth sector by large-sized seeds or multi-seeds while maintaining the microstructure with a low porosity or clean grain boundaries that enables their performance. Here, we report a novel seeding assembly approach by vertically-connecting strip-seeds for inducing potential [110]-oriented overgrowth. Initially, from naturally right-angled corners, YBCO rapidly crystallized to form kite-liked convex areas, which, together with the original seed, effectively functioned as a large-sized seed to generate a sizable c growth sector. The novel-seeded sample exhibited a promising structure not only free of grain boundaries, but also with a favorable porosity of 20.29%. Such a low value is similar to 19.77% of the small-seeded one and much lower than 34.20% of the large-seeded one. Finally, due to structure tailoring towards an enlarged c growth sector with maintained pore characteristics, high and mono-peak trapped fields of 16 mm diameter YBCO bulks were reliably attained, up to a record value of 0.7025 T. This work offers insights into design principles for boosting magnetic properties of other members in the YBCO family.

Horizontal Transfer of Virulence Factors by Pathogenic Enterobacteria to Marine Saprotrophic Bacteria during Co-Cultivation in Biofilm.

Environmental problems associated with marine pollution and climate warming create favorable conditions for the penetration and survival of pathogenic bacteria in marine ecosystems. These microorganisms have interspecific competitive interactions with marine bacteria. Co-culture, as an important research strategy that mimics the natural environment of bacteria, can activate silent genes or clusters through interspecies interactions. The authors used modern biotechnology of co-cultivation to dynamically study intercellular interactions between different taxa of bacteria—pathogenic enterobacteria Yersinia pseudotuberculosis and Listeria monocytogenes and saprotrophic marine bacteria Bacillus sp. and Pseudomonas japonica isolated in summer from the coastal waters of the recreational areas of the Sea of Japan. The results of the experiments showed that during the formation of polycultural biofilms, horizontal transfer of genes encoding some pathogenicity factors from Y. pseudotuberculosis and L. monocytogenes to marine saprotrophic bacteria with different secretion systems is possible. It was previously thought that this was largely prevented by the type VI secretion system (T6SS) found in marine saprotrophic bacteria. The authors showed for the first time the ability of marine bacteria Bacillus sp. and P. japonica to biofilm formation with pathogenic enterobacteria Y. pseudotuberculosis and L. monocytogenes, saprophytic bacteria with type III secretion system (T3SS). For the first time, a marine saprotrophic strain of Bacillus sp. Revealed manifestations of hyaluronidase, proteolytic and hemolytic activity after cultivation in a polycultural biofilm with listeria. Saprotrophic marine bacteria that have acquired virulence factors from pathogenic enterobacteria, including antibiotic resistance genes, could potentially play a role in altering the biological properties of other members of the marine microbial community. In addition, given the possible interdomain nature of intercellular gene translocation, acquired virulence factors can be transferred to marine unicellular and multicellular eukaryotes. The results obtained contribute to the paradigm of the epidemiological significance and potential danger of anthropogenic pollution of marine ecosystems, which creates serious problems for public health and the development of marine culture as an important area of economic activity in coastal regions.

Magnetic structure of magnetoelectric multiferroic HoFeWO6

The polar magnetic oxide, HoFeWO6, is synthesized, and its crystal structure, magnetic structure, and thermodynamic properties are investigated. HoFeWO6 forms the polar crystal structure (space group Pna21 (#33)) due to the cation ordering of W6+ and Fe3+. An antiferromagnetic transition at TN = 17 K is accompanied by a significant change in magnetic entropy with a value of ≈ 5 J kg−1 K−1 in a 70 kOe applied field. Temperature dependent neutron diffraction and magnetization data indicate that the Fe sublattice orders in a strongly non-collinear and non-coplanar arrangement below TN. The Fe ordering initially leads to induced ordering of the Ho spins such that the Ho spins also show behavior of long-range ordering that is evident from the neutron diffraction measurements. Below T ≈ 4 K, the Ho spins order independently and pull the Fe spins toward the direction of Ho spins. A comparison with the magnetic structures and corresponding ferroelectric properties of other members of RMWO6 (R = Y, Sm-Tm, M = Cr, Fe, V) family indicate that the spontaneous polarization is due to the magnetic structure specific to the Fe sublattice through magnetoelectric coupling whereas the polarization is independent of the Ho sublattice.

Oncolytic properties of non-vaccinia poxviruses.

Vaccinia virus, a member of the Poxviridae family, has been extensively used as an oncolytic agent and has entered late stage clinical development. In this study, we evaluated the potential oncolytic properties of other members of the Poxviridae family. Numerous tumor cell lines were infected with ten non-vaccinia poxviruses to identify which virus displayed the most potential as an oncolytic agent. Cell viability indicated that tumor cell lines were differentially susceptible to each virus. Raccoonpox virus was the most potent of the tested poxviruses and was highly effective in controlling cell growth in all tumor cell lines. To investigate further the oncolytic capacity of the Raccoonpox virus, we have generated a thymidine kinase (TK)-deleted recombinant Raccoonpox virus expressing the suicide gene FCU1. This TK-deleted Raccoonpox virus was notably attenuated in normal primary cells but replicated efficiently in numerous tumor cell lines. In human colon cancer xenograft model, a single intratumoral inoculation of the recombinant Raccoonpox virus, in combination with 5-fluorocytosine administration, produced relevant tumor growth control. The results demonstrated significant antitumoral activity of this new modified Raccoonpox virus armed with FCU1 and this virus could be considered to be included into the growing armamentarium of oncolytic virotherapy for cancer.

Transport of Antibiotics through the Substrate Specific OprD Channel of Pseudomonas Aeruginosa

Pseudomonas aeruginosa is a significant cause of nosocomial pneumonia and it is the most prevalent pathogen found in patients with severe injury or burns, where the associated mortality rate is up to 50%. Due to its poorly permeable outer membrane, P. aeruginosa shows strong resistance to a wide range of antibiotics. OprD is a specific porin for basic amino acids and apparently transports some carbapenems, a class of antibiotics with excellent activity against P. aeruginosa. However, there is little direct evidence for a specific binding-site for carbapenems within the OprD channel.With the help of biased molecular dynamics simulations, we aim to understand the structure and function of OprD at the molecular level and thus to elucidate the interaction of drug molecules with this channel. Our study suggests that the movement of loop L2 is a major factor governing ion transport through OprD. It has also been found out that the dynamics of loops L3 and L7 in the constriction region of the porin play a vital role in antibiotic transport as well as in the modulation of ion transport through OprD. The orientation of the carbapenem molecule is important for translocation of the molecule and this is influenced by the electrostatic effect of the basic ladder (constituting of ARG30, ARG39 ARG391 & ARG410) and negatively charged pocket (constituting of TYR176, TYR282 & ASP307) of OprD.Our study is not only helpful to understand the properties of OprD, but it also helps us to understand the properties of other members of the Outer membrane Carboxylic acid Channel (Occ) family. Representatives of this family, which show very high pairwise identity, are found in many pseudomonads and related bacteria.

Doping effects on the magnetic properties of NdRhIn5 intermetallic antiferromagnet

Abstract We report temperature dependent heat capacity and magnetization measurements on single crystals of Nd 1 - x La x RhIn 5 ( x = 0.15 , 0.4 and 0.5) and NdRhIn 5 - x Sn x ( x = 0.08 , 0.12 and 0.24). NdRhIn5 is an antiferromagnetic (AFM) compound with T N ≈ 11 K which crystallizes in the same layered tetragonal structure of the CeMIn5 family ( M = Rh , Co and Ir), where different ground states can be found by tuning the interplay among different microscopic interactions such as the Kondo effect, crystal field (CEF) effects and the Ruderman–Kittel–Kasuya–Yoshida (RKKY) magnetic interaction. Here, we explore the evolution of the AFM correlations in this Nd-based (non-Kondo) compound while perturbing the RKKY exchange by using two different substitutions: (i) replacing Nd 3 + by non-magnetic La 3 + within NdIn3 atomic planes (dilution) and (ii) substituting In by Sn in the In-sites (electronic tuning). For both types of doping, our results show the suppression of the AFM state as the La- or Sn-content is increased. This doping induced suppression of the AFM order is discussed considering the effects of dilution and effects in the tetragonal CEF using a mean-field model applied to the observed data. Our results are compared to the properties of other members of the RRhIn5 family considering the role of dimensionality in the magnetic interactions.

Mapping on the HEALPix grid

The natural spherical projection associated with the Hierarchical Equal-Area and Isolatitude Pixelization (HEALPix) is described and shown to be one of a hybrid class that combines the cylindrical equal-area and Collignon projections, not previously documented in the cartographic literature. Projection equations are derived for the class in general and are used to investigate its properties. It is shown that the HEALPix projection suggests a simple method of (i) storing and (ii) visualizing data sampled on the grid of the HEALPix pixelization, and also suggests an extension of the pixelization that is better suited for these purposes. Potentially useful properties of other members of the class are described, and new triangular and hexagonal pixelizations are constructed from them. Finally, the standard formalism is defined for representing the celestial coordinate system for any member of the class in the FITS data format.

In Vitro Cultivation of an Insect Microsporidian Tubulinosema ratisbonensis in Mammalian Cells

Tubulinosema ratisbonensis is a microsporidian pathogen of Drosophila melanogaster belonging to the family Tubulinosematidae. The microsporidia in this family mainly cause infections in invertebrate hosts, but two members of this family, Brachiola vesicularum and Brachiola algerae, have been found to cause infections in humans as well. Moreover, B. algerae can be transmitted to immunodeficient mice and grows in mammalian cell cultures. Thus, the examination of the opportunistic properties of other members of the family Tubulinosematidae is important. Spores of T. ratisbonensis, isolated from infected fruit flies, were used to inoculate mammalian and insect cell cultures. Parasite growth was only seen in human lung fibroblasts. No growth was seen in Vero cells or insect cell cultures. Comparison of growth kinetics at 31 degrees C and 37 degrees C showed that there were fewer and smaller parasitic foci in cultures incubated at 37 degrees C. Transmission electron microscopy revealed the typical ultrastructure of T. ratisbonensis, and scanning electron microscopy showed oval or slightly pyriform spores, with some spores having extruded their polar tubes. The PCR-amplified sequences of rDNA fragments from infected cell cultures were 100% identical to the original T. ratisbonensis rRNA sequence. As T. ratisbonensis is able to proliferate in mammalian cell cultures, it may have the opportunistic properties of other members of the family Tubulinosematidae.

A Flavoprotein Encoded in Selenomonas ruminantium Is Characterized after Expression in Escherichia coli

Selenomonas ruminantium is an obligate anaerobe that is very important for the provision of vitamin B12 to ruminants, which are particularly dependent upon this cofactor. One important use for vitamin B12 in anaerobic bacteria is for the utilization of glycerol as carbon source. A new flavoprotein has been found expressed by Escherichia coli from a plasmid created as part of a gene library of S. ruminantium. The 2.5-kb fragment of chromosomal DNA responsible for protein expression contains parts of two operons. Only one polypeptide (the flavoprotein) encoded by the S. ruminantium DNA is produced in E. coli in large amounts. The gene for the flavoprotein has been identified and is probably transcribed as part of an operon involved in glycerol metabolism in S. ruminantium. The flavoprotein has been purified and its molecular properties have been examined. Sequence analysis showed that this protein is a divergent member of the family of nitroreductases. Pure protein is a homodimer with a molecular weight of 44,500, containing one molecule of FMN per dimer. Like other nitroreductases, this protein forms a complex with pyridine nucleotide (NADPH), but unlike other nitroreductases, it fails to be reduced in this complex at a biologically significant rate. It has none of the common catalytic properties of other members of the nitroreductase family.

Identification of the Major Autophosphorylation Sites of Nyk/Mer, an NCAM-related Receptor Tyrosine Kinase

Nyk/Mer receptor tyrosine kinase is a new member of the Ufo/Axl tyrosine kinase family and is characterized by its neural cell adhesion molecule-like extracellular domain. By using a vaccinia virus expression system to express a constitutively activated form of Nyk, we identified the major sites of Nyk autophosphorylation in tryptic peptide IY749SGDY753Y754R. Tyr-749, Tyr-753, and Tyr-754 in this peptide lie in the activation loop of the kinase domain. We also studied a series of Nyk mutants in which the three tyrosine residues were replaced individually, in pairs, or all together by phenylalanine. Single mutations of Tyr-749 or Tyr-753 to phenylalanine reduced Nyk kinase activity toward exogenous substrate to 39 or 10% of that of the wild type Nyk, respectively, whereas the Tyr-754 mutant is completely inactive. All of the double and triple Tyr-Phe mutants reduced Nyk kinase activity to a level below the background. Similar results were obtained when Nyk autophosphorylation levels were examined. Our studies suggest that full activity of Nyk/Mer kinase requires phosphorylation of all three tyrosine residues in the kinase domain (Tyr-749, Tyr-753, and Tyr-754) and that Nyk kinase activity is modulated by the level of autophosphorylation in the kinase domain. Given the highly conserved nature of this region among the Ufo/Axl receptor family members, the information presented in this report may provide insight to the biochemical properties of other members of this family.

Stochastic FEM‐Based Validation of LRFD

Stochastic finite‐element based reliability analysis is used to examine the performance of the load and resistance factor design (LRFD) method for steel structures. The reliabilities of members in actual configurations are estimated for both strength and serviceability limit states using the proposed method and compared with the target reliabilities used to derive the LRFD specifications. The dependence of the reliability of a member in an actual structure on the statistical properties of other members, the location of the member in the overall configuration, and the statistical correlations between the various random variables is investigated. The LRFD specifications, which are based on reliability analyses of isolated simple structural elements, are found to result in a conservative design of members in complicated structures, especially when the design is governed by serviceability criteria.

Biochemical characterization of porcine enteric calicivirus: analysis of structural and nonstructural viral proteins

In this report, the molecular weight and antigenicity of the proteins of a porcine enteric calicivirus (PEC) were characterized. The PEC virions were purified from intestinal contents of infected pigs and from infected cell culture lysates. The average buoyant density of the purified virus was 1.37 gm/cm3 in cesium chloride. One major structural protein with a molecular weight of approximately 58 k was found in the gut and cell culture-passaged PEC using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Using immunoblotting techniques only one immunoreactive protein (58 k) ws identified. The PEC and a prototype calicivirus, feline calicivirus (FCV) were propagated in pig kidney and feline kidney (Crandell) cell lines, respectively and intrinsically labeled using [35S]methionine at various times post-inoculation (PI). SDS-PAGE of the radiolabeled proteins indicated the presence of the major structural protein (58 k) and one probable nonstructural protein (28 k) synthesized in the PEC-infected cell lysates by 12 h PI. Other minor protein bands were also evident by 24 h PI (32 k and 82 k). Only the 58 k major protein was detected by radioimmunoprecipitation (RIP) analysis using hyperimmune anti-PEC serum. SDS-PAGE and RIP analysis of FCV-infected cell lysates using hyperimmune anti-FCV serum identified a single major protein of approximately 64 k. No antigenic relationship between PEC and FCV proteins was detected by RIP analysis. The single major structural protein of PEC, the morphological appearance and size of the virus, and its average density of 1.37 gm/cm3 in cesium chloride are consistent with properties of other members of the family Caliciviridae.

Chemical composition and translation products of radish enation mosaic virus isolated in Japan.

Radish enation mosaic virus (RMV) is a member of the comovirus group, but a biochemical characterization of the group has been done only with cowpea mosaic virus (CpMV) which is the type member of the group. Therefore, the biochemical properties of other members of the group, such as RMV, are poorly understood. The present study was an attempt to analyze the nucleic acid, coat protein and gene composition of RMV. The purified RMV was fractionated into the three components (T, M and B components). B and M components were composed of two kinds of coat proteins with molecular weights of 47k and 18k daltons and contained single stranded RNAs with molecular weights of 2.0×106 and 1.6×106 daltons respectively, but T did not contain RNAs. The RNAs contained poly (A) sequences. Then, the B-RNA was in vitro translated into one polypeptide with a molecular weight of 200k daltons in the presence of zinc ions, which inhibited the protease activity. M-RNA was in vitro translated into two polypeptides with molecular weights of 115k and 105k daltons. These products in vitro translated from M and B-RNA were cleaved into eight kinds of polypeptides during incubation without the zinc ions. The results indicated that RMV might have essentially the same chemical composition and translation strategy as cowpea mosaic virus, except that the molecular weights of M-RNA and M-RNA translation products of RMV were quite different from those of CpMV.

The structure of rat mast cell protease II at 1.9-A resolution.

The structure of rat mast cell protease II (RMCP II), a serine protease with chymotrypsin-like primary specificity, has been determined to a nominal resolution of 1.9 A by single isomorphous replacement, molecular replacement, and restrained crystallographic refinement to a final R-factor of 0.191. There are two independent molecules of RMCP II in the asymmetric unit of the crystal. The rms deviation from ideal bond lengths is 0.016 A and from ideal bond angles is 2.7 degrees. The overall structure of RMCP II is extremely similar to that of chymotrypsin, but the largest differences between the two structures are clustered around the active-site region in a manner which suggests that the unusual substrate specificity of RMCP II is due to these changes. Unlike chymotrypsin, RMCP II has a deep cleft around the active site. An insertion of three residues between residues 35 and 41 of chymotrypsin, combined with concerted changes in sequence and a deletion near residue 61, allows residues 35-41 of RMCP II to adopt a conformation not seen in any other serine protease. Additionally, the loss of the disulfide bridge between residues 191 and 220 of chymotrypsin leads to the formation of an additional substrate binding pocket that we propose to interact with the P3 side chain of bound substrate. RMCP II is a member of a homologous subclass of serine proteases that are expressed by mast cells, neutrophils, lymphocytes, and cytotoxic T-cells. Thus, the structure of RMCP II forms a basis for an explanation of the unusual properties of other members of this class.