scholarly journals Characterization of Modular Join-Semilattices

1970 ◽  
Vol 29 ◽  
pp. 43-49
Author(s):  
MR Talukder ◽  
MHB Arif
Keyword(s):  
Key Words ◽  
Classical Characterization ◽  
Join Semilattices ◽  
Distributive Semilattices

In this paper we have proved a classical characterization of modular join-semilattices. We have also given some characterizations of modular ideals of join-semilattices through congruences. Key words: Join-semilattices; modular semilattices; distributive semilattices; quotient semilattices GANIT J. Bangladesh Math. Soc. (ISSN 1606-3694) 29 (2009) 43-49  DOI: http://dx.doi.org/10.3329/ganit.v29i0.8514

Synthesis and characterization of the binuclear diamido titanium chalcogenides [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, Te)

2002 ◽  
Vol 80 (11) ◽  
pp. 1524-1529 ◽  
Author(s):  
Tianle Zhang ◽  
Warren E Piers ◽  
Masood Parvez
Keyword(s):  
Solid State ◽  
Key Words ◽  
Synthesis And Characterization ◽  
Catalyst Precursor ◽  
Tellurium Atom ◽  
Titanium Complex ◽  
X Ray ◽  
X Ray Crystallography ◽  
Atom Source

Reaction of McConville's chelating amido titanium complex [(Ar)NCH2CH2CH2N(Ar)]Ti(CH3)2 (Ar = 2,6-i-Pr2C6H3) with either elemental Se or the tellurium atom source Te=PBu3 resulted in the formation of bis-µ-chalcogenido dimers [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, 2; Te, 3) with concommitant loss of EMe2. The dimers 2 and 3 were characterized spectroscopically and via X-ray crystallography. The two compounds are isostructural in the solid state. The tellurido dimer 3 may also be synthesized by reduction of the diamido dichloride [(Ar)NCH2CH2CH2N(Ar)]2TiCl2 with Na–Hg amalgam followed by treatment with Te=PBu3. This dimer is unreactive toward further Te=PBu3 or stannanes such as HSnBu3. Unlike decamethyltitanocene derivatives, the diamido complex is not an effective catalyst precursor for the heterohydrodecoupling of Te=PBu3 and HSnBu3.Key words: diamido titanium complexes, selenides, tellurides.

scholarly journals PRÜFER ⋆-MULTIPLICATION DOMAINS AND SEMISTAR OPERATIONS

2003 ◽  
Vol 02 (01) ◽  
pp. 21-50 ◽  
Author(s):  
M. FONTANA ◽  
P. JARA ◽  
E. SANTOS
Keyword(s):  
Characterization Theorem ◽  
Field Extensions ◽  
Star Operation ◽  
Classical Characterization ◽  
Integrally Closed ◽  
Prufer Domains ◽  
Semistar Operation ◽  
Prüfer Domains ◽  
The Given

Starting from the notion of semistar operation, introduced in 1994 by Okabe and Matsuda [49], which generalizes the classical concept of star operation (cf. Gilmer's book [27]) and, hence, the related classical theory of ideal systems based on the works by W. Krull, E. Noether, H. Prüfer, P. Lorenzen and P. Jaffard (cf. Halter–Koch's book [32]), in this paper we outline a general approach to the theory of Prüfer ⋆-multiplication domains (or P⋆MDs), where ⋆ is a semistar operation. This approach leads to relax the classical restriction on the base domain, which is not necessarily integrally closed in the semistar case, and to determine a semistar invariant character for this important class of multiplicative domains (cf. also J. M. García, P. Jara and E. Santos [25]). We give a characterization theorem of these domains in terms of Kronecker function rings and Nagata rings associated naturally to the given semistar operation, generalizing previous results by J. Arnold and J. Brewer ]10] and B. G. Kang [39]. We prove a characterization of a P⋆MD, when ⋆ is a semistar operation, in terms of polynomials (by using the classical characterization of Prüfer domains, in terms of polynomials given by R. Gilmer and J. Hoffman [28], as a model), extending a result proved in the star case by E. Houston, S. J. Malik and J. Mott [36]. We also deal with the preservation of the P⋆MD property by ascent and descent in case of field extensions. In this context, we generalize to the P⋆MD case some classical results concerning Prüfer domains and PvMDs. In particular, we reobtain as a particular case a result due to H. Prüfer [51] and W. Krull [41] (cf. also F. Lucius [43] and F. Halter-Koch [34]). Finally, we develop several examples and applications when ⋆ is a (semi)star given explicitly (e.g. we consider the case of the standardv-, t-, b-, w-operations or the case of semistar operations associated to appropriate families of overrings).

Morphological and anatomical characterization of ectomycorrhizas and ectendomycorrhizas on Pinus strobus seedlings in a southern Ontario nursery

1997 ◽  
Vol 75 (12) ◽  
pp. 2057-2072 ◽  
Author(s):  
Margot Ursic ◽  
R. Larry Peterson
Keyword(s):  
Key Words ◽  
Pinus Strobus ◽  
Anatomical Study ◽  
Culture Conditions ◽  
Thelephora Terrestris ◽  
Southern Ontario ◽  
Conifer Seedlings ◽  
The Given ◽  
Pot Culture

A morphological and anatomical study of the mycorrhizas on Pinus strobus L. was conducted on seedlings excavated from St.-Williams nursery in southern Ontario. Micro- and macro-scopic characters were used to classify the morphotypes into complexes and, when possible, genera and species. An E-strain fungus, fungi from the Mycelium radicis atrovirens (MRA) complex, and an unidentified ascomycetous "red-type" fungus formed ectendomycorrhizal (EECM) associations, while Tuber sp., Hebeloma sp., and Thelephora terrestris formed ectomycorrhizal (ECM) associations in the nursery. Cultures of Hebeloma sp., the E-strain fungus, Tuber sp., and two morphologically distinct MRA fungi (MRA1, later identified as Phialophora finlandia Wang & Wilcox, and MRA2, unidentified) were isolated from field-collected morphotypes and re-inoculated onto Pinus strobus seedlings grown in semisterile pot cultures for 4 months. In the resynthesis experiment, the E-strain fungus formed EECM with sparse intracellular colonization, and Tuber sp. formed ECM with characteristic cystidia and densely packed mantles, as they had in the field. However, unlike the MRA field specimens, Phialophora finlandia formed ECM in pot culture. Hebeloma sp., normally an ECM former with conifer seedlings, did not form mycorrhizal structures under the given culture conditions, and neither did the MRA2 isolate. Key words: ectomycorrhiza, ectendomycorrhiza, Pinus strobus, Tuber sp., Phialophora finlandia, E-strain.

Classical characterization of biphoton correlation in waveguide lattices

2011 ◽  
Vol 83 (1) ◽  
Author(s):  
Robert Keil ◽  
Felix Dreisow ◽  
Matthias Heinrich ◽  
Andreas Tünnermann ◽  
Stefan Nolte ◽  
...  
Keyword(s):  
Classical Characterization

Synthesis and characterization of an homologous series of bis(amido)diazadipnictetidines (Pnict = P, As, Sb, Bi)

2001 ◽  
Vol 79 (3) ◽  
pp. 342-348 ◽  
Author(s):  
Neil Burford ◽  
T Stanley Cameron ◽  
Kim-Chung Lam ◽  
Daren J LeBlanc ◽  
Charles LB Macdonald ◽  
...  
Keyword(s):  
Key Words ◽  
General Formula ◽  
Homologous Series ◽  
Spectroscopic Characterization ◽  
Structural Features ◽  
Synthesis And Characterization ◽  
General Reaction ◽  
Coordinative Unsaturation

Spectroscopic and structural features are presented for the first homologous series of diazadipnictetidines, which have the general formula [DipNPnN(H)Dip]2 (Pn = P, As, Sb, Bi; Dip = 2,6-diisopropylphenyl). The compounds are obtained from a general reaction of the corresponding halopnictine with excess LiN(H)Dip, which was previously reported for [DipNBiN(H)Dip]2. However, isolation is improved by the introduction of LiN(H)-t-Bu (at the appropriate stoichiometry) following the addition of LiN(H)Dip. The intermediate steric presence of the Dip substituent is suitable to support the heterocatenate framework for all homologues. This is in contrast to the small substituents (e.g. alkyl), which enable both bis- and tris-amination, and the larger substituent (Mes* = tri-tert-butylphenyl), which can impose coordinative unsaturation (aminoiminopnictine) for the smaller congeners (P and As).Key words: phosphorus, arsenic, antimony, bismuth, phosphazanes, phosphetidines, synthesis, structures, spectroscopic characterization.

Powder diffraction study of arsenic-substituted nasicon structures MeZr2As(3−x)PxO12 (Me=Na+, K+)

1998 ◽  
Vol 13 (4) ◽  
pp. 227-231 ◽  
Author(s):  
D. Mazza ◽  
M. Lucco-Borlera ◽  
S. Ronchetti
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Key Words ◽  
Powder Diffraction ◽  
Mixed Oxides ◽  
Structural Data ◽  
Nasicon Structure ◽  
Ionic Conductors ◽  
X Ray

Three new mixed oxides having the nasicon structure and containing arsenic(V) as tetrahedral ion were prepared and X-ray analyzed. The stoichiometry of the three phases can be expressed by the comprehensive notation MeZr2As(3−x)PxO12 where Me stands for Na+ or K+, x equals to 0 and 1.5 when Me=Na, while x equals to 1.5 when Me=K. For two other compositions of the above series, the powder patterns were calculated on the basis of the structural data from single crystal determinations, thus permitting us to complete the characterization of the solids, with nasicon framework, deriving from MeZr2P3O12 (Me=Na+, K+) by partial (50%) or complete (100%) substitution of As for P.Key words: nasicon, ionic conductors, phosphates, arsenates

Genetic characterization of partial lactose-fermenting revertants from lactose-negative mutants of lactococci

1991 ◽  
Vol 37 (4) ◽  
pp. 281-286 ◽  
Author(s):  
R. P. Sinha
Keyword(s):  
Key Words ◽  
Plasmid Dna ◽  
Genetic Information ◽  
Genetic Characterization ◽  
Skim Milk ◽  
Starter Cultures ◽  
Chromosomal Gene ◽  
Cheese Ripening ◽  
Lactose Fermentation

Partial lactose-positive (Lac+) revertants, designated RS0121 and RS033, were isolated from lactose-negative (Lac−) mutants of Lactococcus lactis subsp. lactis C2 and ML3, respectively. These revertants were found to coagulate 10% reconstituted skim milk, but the rate of lactose fermentation was much slower than that of their parental Lac+ strains. Such partial Lac+ revertants were also isolated from Lac− mutants of L. lactis subsp. Lactis SL712, SH4109, and SL763 and of L. lactis subsp. cremoris ML1 and SC607, showing a generalized phenomenon. The Lac+ characteristic of the revertant strains was conjugally transferred to Lac− variants. When the plasmid profiles of the Lac− variants and their partial Lac+ revertants and transconjugants were analyzed, there were no detectable differences in the plasmid bands. A strain with no plasmids, MG1363, also yielded partial Lac+ revertants, which were devoid of all plasmids. In addition, the Lac+ phenotype of one such revertant, designated RS101, was transferable to other Lac− strains by conjugation. The results indicate that the genetic information for slow lactose metabolism in such partial Lac+ revertants is mediated through chromosomal gene(s) and is under the influence of some suppressor. These observations also suggest the possibility of utilizing this method for isolating slow acid producing variants, which could be used as adjuncts with regular cheese starter cultures for accelerated cheese ripening. Key words: lactococci, lactose-negative mutants, plasmid DNA, lactose-fermenting revertants.

Use of critical state representations of sand in the method of stress characteristics

1987 ◽  
Vol 24 (3) ◽  
pp. 441-446 ◽  
Author(s):  
M. G. Jefferies ◽  
K. Been
Keyword(s):  
Bearing Capacity ◽  
Key Words ◽  
Critical State ◽  
Method Of Characteristics ◽  
Kinematic Constraint ◽  
Kinematic Constraints ◽  
The Method Of Characteristics ◽  
State Stress

The limitations of critical state representations of sand behaviour are discussed and it is shown that stress dilatancy is an implicit part of a critical state framework. It is then argued that dilatancy leads to underestimates of bearing capacity factors in the method of characteristics. Kinematic constraints should also be considered in such calculations. Both dilatancy and kinematic constraint may be introduced into a stress characteristics approach while preserving critical state characterization of sand, using the technique known as the method of associated fields. Key words: bearing capacity, critical state, stress dilatancy, method of characteristics.

Chlamydomonas reinhardtii cDNAs upregulated in low-CO2 conditions: expression and analyses

1998 ◽  
Vol 76 (6) ◽  
pp. 1003-1009
Author(s):  
Aravind Somanchi ◽  
Eric R Handley ◽  
James V Moroney
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Chlamydomonas Reinhardtii ◽  
Key Words ◽  
Cdna Clones ◽  
Low Co2 ◽  
Unicellular Algae ◽  
Concentrating Mechanism ◽  
Inducible Genes

Unicellular algae acquire the ability to raise their internal CO2 concentrations under low-CO2 conditions because of the presence of a CO2 concentrating mechanism (CCM). In Chlamydomonas reinhardtii, this mechanism is induced when cells grown in high-CO2 conditions are switched to low-CO2 conditions. To elucidate the genes and proteins involved in this mechanism, we constructed a cDNA library from low CO2 adapted cells and differentially screened the library for cDNAs upregulated under low-CO2 conditions. Earlier studies identified six classes of clones specific to low CO2 adapting cells. To identify other genes and proteins playing a role in this mechanism, we have systematically characterized the cDNA clones that appear to be upregulated by low-CO2 adaptation but do not cross-hybridize with the six previously identified classes. We identified seven new classes of clones that are distinctly upregulated in low-CO2 conditions. These clones were checked by Northern analyses, sequencing, and homology studies. One class of clone represents a novel gene, lci 3. We report on the seven classes of clones and the characterization of lci 3.Key words: Chlamydomonas, CO2 concentrating mechanism, gene regulation, inducible genes, gene expression.

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