A (0, 2)-graph is a connected graph, where each pair of vertices has either 0 or 2 common neighbours. These graphs constitute a subclass of (0, λ)-graphs introduced by Mulder in 1979. A rectagraph, well known in diagram geometry, is a triangle-free (0, 2)-graph. (0, 2)-graphs include hypercubes, folded cube graphs and some particular graphs such as icosahedral graph, Shrikhande graph, Klein graph, Gewirtz graph, etc. In this paper, we give some local properties of 4-cycles in (0, λ)-graphs and more specifically in (0, 2)-graphs, leading to new characterizations of rectagraphs and hypercubes., Khadra Bouanane, Abdelhafid Berrachedi., and Obsahuje bibliografii
Diatomite is a siliceous sedimentary rock, and it can be used in many industrial applications due to its high porosity, low density porous and permeable structure, chemical resistance, high purity, high specific surface area, absorptive capacity and to its absorbent properties. The best known Portuguese occurrences of diatomite are located in the regions of Óbidos and Rio Maior. The purpose of this research is to characterize the Rio Maior and Amieira diatomite and beneficiate this rock to be used in some potential applications locally or not. The studied diatomites present a fine texture; chemically the samples have a high SiO2 content, the principal minerlas are quartz and amorphous opal. The studied diatomites benefited with temperature and addition of NaCl (acting as accelerator of the crystallization process), with 5 % of NaCl being reduced the transformation temperature of the amorphous opal in opal C / CT at about 200 ºC. The diatomites from Rio Maior and Amieira in natural state has an enormous potential as absorbent, of heavy metals (e.g. in soil contamination) or dyes (textile industry). These diatomites after beneficiation can be used in construction materials (as additive), being more reactive and crystalline than in the natural state, diatomites can be promoters of mechanical resistance in mortars and geopolymers. and Costa Cristiana, Velosa Ana, Cerqueira Angela, Caetano Paulo, Rocha Fernando.
In this paper, the concepts of indecomposable matrices and fully indecomposable matrices over a distributive lattice $L$ are introduced, and some algebraic properties of them are obtained. Also, some characterizations of the set $F_n(L)$ of all $n\times n$ fully indecomposable matrices as a subsemigroup of the semigroup $H_n(L)$ of all $n\times n$ Hall matrices over the lattice $L$ are given.
A graph G is a k-tree if either G is the complete graph on k + 1 vertices, or G has a vertex v whose neighborhood is a clique of order k and the graph obtained by removing v from G is also a k-tree. Clearly, a k-tree has at least k + 1 vertices, and G is a 1-tree (usual tree) if and only if it is a 1-connected graph and has no K_{3} -minor. In this paper, motivated by some properties of 2-trees, we obtain a characterization of k-trees as follows: if G is a graph with at least k + 1 vertices, then G is a k-tree if and only if G has no K_{k+2} -minor, G does not contain any chordless cycle of length at least 4 and G is k-connected., De-Yan Zeng, Jian-Hua Yin., and Obsahuje seznam literatury
Pyridoxal kinase (PLK; EC 2.7.1.35) is a key enzyme in the metabolism of vitamin B6 (VB6) in Bombyx mori. A fusion expressional vector pET-22b-BPLK-His was constructed using a sub-cloning technique, the recombinant B. mori PLK was then expressed in Escherichia coli, purified and characterized. Bioinformatics were used to deduce the protein structure and genomic organization of this enzyme. Using Ni Sepharose affinity column chromatography, the recombinant protein was purified to very high degree (approximately 90%). The recombinant PLK exhibits a high specific enzymatic activity (1800 nmol/min/mg of protein). The maximum catalytic activity of this enzyme was recorded over a narrow pH range (5.5-6.0) and Zn2+ is the most effective cation for catalysis under saturating substrate concentrations. When only triethanolamine is present as the cation, K+ is an activator of PLK. A double reciprocal plot of initial velocity suggests that the enzyme catalyses the reaction by means of a sequential catalytic mechanism. Under optimal conditions, the Km value for the substrates of ATP and pyridoxal are 57.9 ± 5.1 and 44.1 ± 3.9 µM. B. mori's genome contains a single copy of the PLK gene, which is 7.73 kb long and contains five exons and four introns, and is located on the eighth chromosome. The PLK may be a dimer with two identical subunits under native conditions, and it is hypothesized that each monomer contains eight α-helices (α1-8), nine β-strands (β1-9) and two segments of 310 helices. and Shuo-Hao HUANG, Wang MA, Ping-Ping ZHANG, Jian-Yun ZHANG, Yan-Feng XIE, Long-Quan HUANG.
The article considers the nature of descriptive statements and the ontological status of descriptive constructs in linguistics, taking the example of a phoneme of English. It is argued that descriptive statements should be seen as expressions of the content of descriptive models or as hypotheses. Furthermore, it is argued that descriptive models and constructs in linguistics have a purely explanatory function in relation to speech events and without ontological commitment to corresponding entities in the real world., Článek pojednává o povaze popisných výroků a ontologickém stavu deskriptivních konstrukcí v lingvistice, přičemž vychází z příkladu fonému angličtiny. Argumentuje se tím, že popisná prohlášení by měla být chápána jako vyjádření obsahu popisných modelů nebo jako hypotézy. Dále, to je argumentoval, že popisné modely a konstrukce v lingvistice mají čistě vysvětlující funkci ve vztahu k událostem řeči a bez ontologického závazku k odpovídajícím entitám v reálném světě., and Paul Rastall