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Keywords = annihilator in ring

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11 pages, 263 KB  
Article
On the Conditions Under Which an Algebra over a Field Has a Multiplicative Identity Element
by Małgorzata Jastrzębska
Symmetry 2025, 17(7), 1128; https://doi.org/10.3390/sym17071128 - 14 Jul 2025
Viewed by 399
Abstract
The set of all annihilators in a ring forms a lattice whose structure reflects the internal properties of the ring. In contrast to the lattices of one-sided ideals, lattices of one-sided annihilators possess a particularly desirable property: symmetry. More precisely, the lattice of [...] Read more.
The set of all annihilators in a ring forms a lattice whose structure reflects the internal properties of the ring. In contrast to the lattices of one-sided ideals, lattices of one-sided annihilators possess a particularly desirable property: symmetry. More precisely, the lattice of left annihilators in a given ring is anti-isomorphic to the lattice of right annihilators. In the literature, attention is primarily focused on rings with identity. In this work, we study lattices of one-sided annihilators in rings without a multiplicative identity element. The properties of rings with an identity element usually differ significantly from those of rings without an identity. We restrict our consideration to rings that are algebras over fields. We indicate certain connections between algebras A without identity and their extensions to algebras A1 with identity (we consider the Dorroh extension). We highlight similarities and differences in the structure of the lattices of one-sided annihilators in A and those in A1. We also identify conditions on annihilators in semiprimary algebras that ensure the existence of an identity element. Furthermore, we show that the existence of an identity in an algebra A is not guaranteed even if A satisfies the condition A2=A and possesses a one-sided identity. Full article
(This article belongs to the Section Mathematics)
13 pages, 280 KB  
Article
Exploring Geometrical Properties of Annihilator Intersection Graph of Commutative Rings
by Ali Al Khabyah and Moin A. Ansari
Axioms 2025, 14(5), 336; https://doi.org/10.3390/axioms14050336 - 27 Apr 2025
Cited by 1 | Viewed by 592
Abstract
Let Λ denote a commutative ring with unity and D(Λ) denote a collection of all annihilating ideals from Λ. An annihilator intersection graph of Λ is represented by the notation AIG(Λ). This graph is not [...] Read more.
Let Λ denote a commutative ring with unity and D(Λ) denote a collection of all annihilating ideals from Λ. An annihilator intersection graph of Λ is represented by the notation AIG(Λ). This graph is not directed in nature, where the vertex set is represented by D(Λ)*. There is a connection in the form of an edge between two distinct vertices ς and ϱ in AIG(Λ) iff Ann(ςϱ)Ann(ς)Ann(ϱ). In this work, we begin by categorizing commutative rings Λ, which are finite in structure, so that AIG(Λ) forms a star graph/2-outerplanar graph, and we identify the inner vertex number of AIG(Λ). In addition, a classification of the finite rings where the genus of AIG(Λ) is 2, meaning AIG(Λ) is a double-toroidal graph, is also investigated. Further, we determine Λ, having a crosscap 1 of AIG(Λ), indicating that AIG(Λ) is a projective plane. Finally, we examine the domination number for the annihilator intersection graph and demonstrate that it is at maximum, two. Full article
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19 pages, 3997 KB  
Article
The Triplet–Triplet Annihilation Efficiency of Some 9,10-Substituted Diphenyl Anthracene Variants—A Decisive Analysis from Kinetic Rate Constants
by Mikael Lindgren, Victoria M. Bjelland, Thor-Bernt Melø, Callum McCracken, Satoshi Seo and Harue Nakashima
Optics 2025, 6(1), 8; https://doi.org/10.3390/opt6010008 - 12 Mar 2025
Viewed by 1685
Abstract
Triplet–triplet transfer photochemical reactions are essential in many biological, chemical, and photonic applications. Here, the Pd-octaethylporphyrin sensitizer along with triplet–triplet annihilator (TTA) active 9,10-diphenylantracenes (DPA) and the related substituted variants in low concentrations were examined. A full experimental approach is presented for finding [...] Read more.
Triplet–triplet transfer photochemical reactions are essential in many biological, chemical, and photonic applications. Here, the Pd-octaethylporphyrin sensitizer along with triplet–triplet annihilator (TTA) active 9,10-diphenylantracenes (DPA) and the related substituted variants in low concentrations were examined. A full experimental approach is presented for finding the necessary rate parameters with statistical standard deviation parameters. This was achieved by solving the pertinent non-analytical kinetic differential equation and fitting it to the experimental time-resolved photoluminescence of both slow fluorescence and sensitizer phosphorescence. The efficiency of the triplet–triplet energy transfer rate was found to be around 90% in THF but only around 75% in toluene. This appears to follow from the shorter lifetime of the sensitizer triplet in toluene. Moreover, the TTA transfer rate was on average more than 40% in THF toluene whereas a considerably lower value around 20–30% was found for toluene. This originated in an order of magnitude higher solvent quenching rate using toluene, based on the analysis of the delayed fluorescence decay traces. These are also higher than the statistically expected 1/9 TTA efficiency but in accordance with recent results in the literature, that attributed these high values to an inverse intersystem crossing process. In addition, quantum chemical calculations were carried out to reveal the pertinent excited triplet molecular orbitals of the lowest triplet excited state for a series of substituted DPAs, in comparison with the singlet ground state. Conclusively, these states distribute mainly in an anthracene ring in all compounds being in the range 1.64–1.65 eV above the ground state. The TTA efficiency was found to vary depending on the DPA annihilator substitution scheme and found to be smaller in THF. This is likely because the molecular framework over which the T1 excited molecular orbitals distribute is less sensitive for a longer lifetime of the annihilator triplet state. Full article
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19 pages, 644 KB  
Article
On Nilpotent Elements, Weak Symmetry and Related Properties of Skew Generalized Power Series Rings
by Ryszard Mazurek
Symmetry 2024, 16(12), 1693; https://doi.org/10.3390/sym16121693 - 20 Dec 2024
Viewed by 1021
Abstract
The skew generalized power series ring R[[S,ω]] is a ring construction involving a ring R, a strictly ordered monoid (S,), and a monoid homomorphism [...] Read more.
The skew generalized power series ring R[[S,ω]] is a ring construction involving a ring R, a strictly ordered monoid (S,), and a monoid homomorphism ω:SEnd(R). The ring R[[S,ω]] is a common generalization of ring extensions such as (skew) polynomial rings, (skew) Laurent polynomial rings, (skew) power series rings, (skew) Laurent series rings, (skew) Mal’cev–Neumann series rings, and (skew) monoid rings. In this paper, we study the nilpotent elements of skew generalized power series rings and the relationships between the properties of the rings R and R[[S,ω]] expressed in terms of annihilators, such as weak symmetry, weak zip, and the nil-Armendariz and McCoy properties. We obtain results on transferring the weak symmetry and weak zip properties between the rings R and R[[S,ω]], as well as sufficient and necessary conditions for a ring R to be (S,ω)-nil-Armendariz or linearly (S,ω)-McCoy. Full article
(This article belongs to the Section Mathematics)
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23 pages, 18733 KB  
Article
Antioxidant Scavenging of the Superoxide Radical by Yerba Mate (Ilex paraguariensis) and Black Tea (Camellia sinensis) Plus Caffeic and Chlorogenic Acids, as Shown via DFT and Hydrodynamic Voltammetry
by Francesco Caruso, Raiyan Sakib, Stuart Belli, Alessio Caruso and Miriam Rossi
Int. J. Mol. Sci. 2024, 25(17), 9342; https://doi.org/10.3390/ijms25179342 - 28 Aug 2024
Cited by 3 | Viewed by 1442
Abstract
We describe the antioxidant capability of scavenging the superoxide radical of several tea and yerba mate samples using rotating ring–disk electrochemistry (RRDE). We directly measured superoxide concentrations and detected their decrease upon the addition of an antioxidant to the electrochemical cell. We studied [...] Read more.
We describe the antioxidant capability of scavenging the superoxide radical of several tea and yerba mate samples using rotating ring–disk electrochemistry (RRDE). We directly measured superoxide concentrations and detected their decrease upon the addition of an antioxidant to the electrochemical cell. We studied two varieties of yerba mate, two varieties of black tea from Bangladesh, a sample of Pu-erh tea from China, and two components, caffeic acid and chlorogenic acid. All of these plant infusions and components showed strong antioxidant activities, virtually annihilating the available superoxide concentration. Using density functional theory (DFT) calculations, we describe a mechanism of superoxide scavenging via caffeic and chlorogenic acids. Superoxide can initially interact at two sites in these acids: the H4 catechol hydrogen (a) or the acidic proton of the acid (b). For (a), caffeic acid needs an additional π–π superoxide radical, which transfers electron density to the ring and forms a HO2 anion. A second caffeic acid proton and HO2 anion forms H2O2. Chlorogenic acid acts differently, as the initial approach of superoxide to the catechol moiety (a) is enough to form the HO2 anion. After an additional acidic proton of chlorogenic acid is given to HO2, three well-separated compounds arise: (1) a carboxylate moiety, (2) H2O2, and a (3) chlorogenic acid semiquinone. The latter can capture a second superoxide in a π–π manner, which remains trapped due to the aromatic ring, as for caffeic acid. With enough of both acids and superoxide radicals, the final products are equivalent: H2O2 plus a complex of the type [X-acid–η–O2], X = caffeic, chlorogenic. Chlorogenic acid (b) is described by the following reaction: 2 O2•− + 2 chlorogenic acid → 2 chlorogenic carboxylate + O2 + H2O2, and so, it acts as a non-enzymatic superoxide dismutase (SOD) mimic, as shown via the product formation of O2 plus H2O2, which is limited due to chlorogenic acid consumption. Caffeic acid (b) differs from chlorogenic acid, as there is no acidic proton capture via superoxide. In this case, approaching a second superoxide to the H4 polyphenol moiety forms a HO2 anion and, later, an H2O2 molecule upon the transfer of a second caffeic acid proton. Full article
(This article belongs to the Section Biochemistry)
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27 pages, 6045 KB  
Article
Nanostructured Molecular–Network Arsenoselenides from the Border of a Glass-Forming Region: A Disproportionality Analysis Using Complementary Characterization Probes
by Oleh Shpotyuk, Malgorzata Hyla, Adam Ingram, Yaroslav Shpotyuk, Vitaliy Boyko, Pavlo Demchenko, Renata Wojnarowska-Nowak, Zdenka Lukáčová Bujňáková and Peter Baláž
Molecules 2024, 29(16), 3948; https://doi.org/10.3390/molecules29163948 - 21 Aug 2024
Cited by 2 | Viewed by 1334
Abstract
Binary AsxSe100−x alloys from the border of a glass-forming region (65 < x < 70) subjected to nanomilling in dry and dry–wet modes are characterized by the XRPD, micro-Raman scattering (micro-RS) and revised positron annihilation lifetime (PAL) methods complemented by [...] Read more.
Binary AsxSe100−x alloys from the border of a glass-forming region (65 < x < 70) subjected to nanomilling in dry and dry–wet modes are characterized by the XRPD, micro-Raman scattering (micro-RS) and revised positron annihilation lifetime (PAL) methods complemented by a disproportionality analysis using the quantum–chemical cluster modeling approach. These alloys are examined with respect to tetra-arsenic biselenide As4Se2 stoichiometry, realized in glassy g-As65Se35, glassy–crystalline g/c-As67Se33 and glassy–crystalline g/c-As70Se30. From the XRPD results, the number of rhombohedral As and cubic arsenolite As2O3 phases in As-Se alloys increases after nanomilling, especially in the wet mode realized in a PVP water solution. Nanomilling-driven amorphization and reamorphization transformations in these alloys are identified by an analysis of diffuse peak halos in their XRPD patterning, showing the interplay between the levels of a medium-range structure (disruption of the intermediate-range ordering at the cost of an extended-range one). From the micro-RS spectroscopy results, these alloys are stabilized by molecular thioarsenides As4Sen (n = 3, 4), regardless of their phase composition, remnants of thioarsenide molecules destructed under nanomilling being reincorporated into a glass network undergoing a polyamorphic transition. From the PAL spectroscopy results, volumetric changes in the wet-milled alloys with respect to the dry-milled ones are identified as resulting from a direct conversion of the bound positron–electron (Ps, positronium) states in the positron traps. Ps-hosting holes in the PVP medium appear instead of positron traps, with ~0.36–0.38 ns lifetimes ascribed to multivacancies in the As-Se matrix. The superposition of PAL spectrum peaks and tails for pelletized PVP, unmilled, dry-milled, and dry–wet-milled As-Se samples shows a spectacular smoothly decaying trend. The microstructure scenarios of the spontaneous (under quenching) and activated (under nanomilling) decomposition of principal network clusters in As4Se2-bearing arsenoselenides are recognized. Over-constrained As6·(2/3) ring-like network clusters acting as pre-cursors of the rhombohedral As phase are the main products of this decomposition. Two spontaneous processes for creating thioarsenides with crystalline counterparts explain the location of the glass-forming border in an As-Se system near the As4Se2 composition, while an activated decomposition process for creating layered As2Se3 structures is responsible for the nanomilling-driven molecular-to-network transition. Full article
(This article belongs to the Special Issue Exclusive Feature Papers in Physical Chemistry, 2nd Edition)
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31 pages, 43899 KB  
Article
“Polymerization” of Bimerons in Quasi-Two-Dimensional Chiral Magnets with Easy-Plane Anisotropy
by Natsuki Mukai and Andrey O. Leonov
Nanomaterials 2024, 14(6), 504; https://doi.org/10.3390/nano14060504 - 11 Mar 2024
Cited by 9 | Viewed by 2520
Abstract
We re-examine the internal structure of bimerons, which are stabilized in easy-plane chiral magnets and represent coupled states of two merons with the same topological charge |1/2| but with opposite vorticity and the polarity. We find that, in addition [...] Read more.
We re-examine the internal structure of bimerons, which are stabilized in easy-plane chiral magnets and represent coupled states of two merons with the same topological charge |1/2| but with opposite vorticity and the polarity. We find that, in addition to the vortices and antivortices, bimerons feature circular regions which are located behind the anti-vortices and bear the rotational sense opposite to the rotational sense chosen by the Dzyaloshinskii–Moriya interaction. In an attempt to eliminate these wrong-twist regions with an excess of positive energy density, bimerons assemble into chains, and as such exhibit an attracting interaction potential. As an alternative to chains, we demonstrate the existence of ring-shaped bimeron clusters of several varieties. In some rings, bimeron dipoles are oriented along the circle and swirl clockwise and/or counterclockwise (dubbed “roundabouts”). Moreover, a central meron encircled by the outer bimerons may possess either positive or negative polarity. In other rings, the bimeron dipoles point towards the center of a ring and consequently couple to the central meron (dubbed “crossings”). We point out that the ringlike solutions for baryons obtained within the Skyrme model of pions, although driven by the same tendency of the energy reduction, yield only one type of bimeron rings. The conditions of stability applied to the described bimeron rings are additionally extended to bimeron networks when bimerons fill the whole space of two-dimensional samples and exhibit combinations of rings and chains dispersed with different spatial density (dubbed bimeron “polymers”). In particular, bimeron crystals with hexagonal and the square bimeron orderings are possible when the sides of the unit cells represent chains of bimerons joined in intersections with three or four bimerons, respectively; otherwise, bimeron networks represent disordered bimeron structures. Moreover, we scrutinize the inter-transformations between hexagonal Skyrmion lattices and disordered bimeron polymers occuring via nucleation and mutual annihilation of merons within the cell boundaries. Our theory provides clear directions for experimental studies of bimeron orderings in different condensed-matter systems with quasi-two-dimensional geometries. Full article
(This article belongs to the Section Theory and Simulation of Nanostructures)
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12 pages, 2619 KB  
Article
Nano-Architectonics of Antibiotic-Loaded Polymer Particles as Vehicles for Active Molecules
by Norin Forna, Daniela Damir, Letitia Doina Duceac, Marius Gabriel Dabija, Gabriela Calin, Daniela Luminita Ichim, Cristian Gutu, Carmen Grierosu, Lucian Eva, Mădălina Irina Ciuhodaru, Elena Roxana Bogdan Goroftei, Elena Ariela Banu, Liviu Stafie, Ciolpan Gabriela, Geta Mitrea and Constantin Marcu
Appl. Sci. 2022, 12(4), 1998; https://doi.org/10.3390/app12041998 - 14 Feb 2022
Cited by 18 | Viewed by 3298
Abstract
Recently, nanotechnology research studies have been proven that use of various nanoparticles as drug delivery systems to target and to annihilate pathogenic microorganisms may be a good solution for prevention and treatment of severe infection. In the last few years, antimicrobial drug encapsulation [...] Read more.
Recently, nanotechnology research studies have been proven that use of various nanoparticles as drug delivery systems to target and to annihilate pathogenic microorganisms may be a good solution for prevention and treatment of severe infection. In the last few years, antimicrobial drug encapsulation into nano-sized systems has materialized as a promising alternative that increased drug efficacy and minimized adverse effects. Physicochemical properties of erythromycin-loaded polymer nanoparticles were assessed using particle size distribution, HPLC, FTIR, TG/DTA, and SEM characterization techniques. The as-prepared samples exhibited an average particle size of 340 and 270 nm, respectively, with erythromycin content of 99.7% in both samples. From the release profile of erythromycin from PLA/PLGA, a prolonged drug release can be observed from both Ery-PLA and Ery-PLGA nanostructures. Morphology images exhibited spherical, rigid, and ring-shaped nanoparticles. Thermal analytical study in the case of Ery-PLA and Ery-PLGA samples showed that pure drug has an endothermic peak at around 150 °C assigned to a melting point. The antibiotic melting peak disappeared for both antibiotic-loaded PLA and PLGA nanoparticles thermographs, denoting the presence of erythromycin. This indicates that the antibiotic is uniformly dispensed throughout the host polymer matrix at nanometer scale. FTIR spectra of Ery-PLA and Ery-PLGA nano-architectures with almost similar peaks indicated no alteration in chemical structure of drug-loaded polymer nanoparticles. Full article
(This article belongs to the Special Issue New Materials and Advanced Procedures of Obtaining and Processing)
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9 pages, 276 KB  
Article
Rings with Boolean Lattices of One-Sided Annihilators
by Małgorzata Jastrzębska
Symmetry 2021, 13(10), 1909; https://doi.org/10.3390/sym13101909 - 11 Oct 2021
Cited by 2 | Viewed by 2028
Abstract
The present paper is part of the research on the description of rings with a given property of the lattice of left (right) annihilators. The anti-isomorphism of lattices of left and right annihilators in any ring gives some kind of symmetry: the lattice [...] Read more.
The present paper is part of the research on the description of rings with a given property of the lattice of left (right) annihilators. The anti-isomorphism of lattices of left and right annihilators in any ring gives some kind of symmetry: the lattice of left annihilators is Boolean (complemented, distributive) if and only if the lattice of right annihilators is such. This allows us to restrict our investigations mainly to the left side. For a unital associative ring R, we prove that the lattice of left annihilators in R is Boolean if and only if R is a reduced ring. We also prove that the lattice of left annihilators of R being two-sided ideals is complemented if and only if this lattice is Boolean. The last statement, in turn, is known to be equivalent to the semiprimeness of R. On the other hand, for any complete lattice L, we construct a nilpotent ring whose lattice of left annihilators coincides with its sublattice of left annihilators being two-sided ideals and is isomorphic to L. This construction shows that the assumption of R being unital cannot be dropped in any of the above two results. Some additional results on rings with distributive or complemented lattices of left annihilators are obtained. Full article
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17 pages, 360 KB  
Review
Image of the Electron Suggested by Nonlinear Electrodynamics Coupled to Gravity
by Irina Dymnikova
Particles 2021, 4(2), 129-145; https://doi.org/10.3390/particles4020013 - 26 Mar 2021
Cited by 10 | Viewed by 3337
Abstract
We present a systematic review of the basic features that were adopted for different electron models and show, in a brief overview, that, for electromagnetic spinning solitons in nonlinear electrodynamics minimally coupled to gravity (NED-GR), all of these features follow directly from NED-GR [...] Read more.
We present a systematic review of the basic features that were adopted for different electron models and show, in a brief overview, that, for electromagnetic spinning solitons in nonlinear electrodynamics minimally coupled to gravity (NED-GR), all of these features follow directly from NED-GR dynamical equations as model-independent generic features. Regular spherically symmetric solutions of NED-GR equations that describe electrically charged objects have obligatory de Sitter center due to the algebraic structure of stress–energy tensors for electromagnetic fields. By the Gürses-Gürsey formalism, which includes the Newman–Janis algorithm, they are transformed to axially symmetric solutions that describe regular spinning objects asymptotically Kerr–Newman for a distant observer, with the gyromagnetic ratio g=2. Their masses are determined by the electromagnetic density, related to the interior de Sitter vacuum and to the breaking of spacetime symmetry from the de Sitter group. De Sitter center transforms to the de Sitter vacuum disk, which has properties of a perfect conductor and ideal diamagnetic. The ring singularity of the Kerr–Newman geometry is replaced with the superconducting current, which serves as the non-dissipative source for exterior fields and source of the intrinsic magnetic momentum for any electrically charged spinning NED-GR object. Electromagnetic spinning soliton with the electron parameters can shed some light on appearance of a minimal length scale in the annihilation reaction e+eγγ(γ). Full article
21 pages, 5975 KB  
Article
Structure-Gas Barrier Property Relationship in a Novel Polyimide Containing Naphthalene and Amide Groups: Evaluation by Experiments and Simulations
by Yi Zeng, Yiwu Liu, Jinghua Tan, Jie Huang, Junjie Liu, Ao Tang, Chengliang Chen and Hong Chen
Materials 2021, 14(6), 1402; https://doi.org/10.3390/ma14061402 - 13 Mar 2021
Cited by 5 | Viewed by 2907
Abstract
In order to meet the increasingly stringent requirements for heat resistance and barrier properties in the packaging and electronic device encapsulation field. A high-barrier polyimide (NAPPI) contains naphthalene ring and amide group was prepared by polymerization of a novel diamine (NAPDA) and pyromellitic [...] Read more.
In order to meet the increasingly stringent requirements for heat resistance and barrier properties in the packaging and electronic device encapsulation field. A high-barrier polyimide (NAPPI) contains naphthalene ring and amide group was prepared by polymerization of a novel diamine (NAPDA) and pyromellitic dianhydride. The structure and properties of diamine monomers and polymers were characterized. Results show that the NAPPI exhibits superior barrier properties with extremely low water vapor and oxygen transmission rate values of 0.14 g·m−2·day−1 and 0.04 cm3·m−2·day−1, respectively. In addition, the NAPPI presents outstanding mechanical properties and thermal stability as well. This article attempts to explore the relationship between NAPPI structure and barrier properties by combining experiment and simulation. Studies on positron annihilation lifetime spectroscopy, Wide angle X-ray diffractograms and molecular dynamics simulations prove that the NAPPI has smaller interplanar spacing and higher chain regularity. In addition, the strong chain rigidity and interchain cohesion of NAPPI due to the presence of the rigid naphthalene ring and a large number of hydrogen bond interactions formed by amide groups result in compact chain packing and smaller free volume, which reduces the solubility and diffusibility of small molecules in the matrix. In general, the simulation results are consistent with the experimental results, which are important for understanding the barrier mechanism of NAPPI. Full article
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15 pages, 318 KB  
Article
Composite Hurwitz Rings as PF-Rings and PP-Rings
by Dong Kyu Kim and Jung Wook Lim
Mathematics 2020, 8(1), 100; https://doi.org/10.3390/math8010100 - 7 Jan 2020
Cited by 1 | Viewed by 2356
Abstract
Let R T be an extension of commutative rings with identity and H ( R , T ) (respectively, h ( R , T ) ) the composite Hurwitz series ring (respectively, composite Hurwitz polynomial ring). In this article, we study equivalent [...] Read more.
Let R T be an extension of commutative rings with identity and H ( R , T ) (respectively, h ( R , T ) ) the composite Hurwitz series ring (respectively, composite Hurwitz polynomial ring). In this article, we study equivalent conditions for the rings H ( R , T ) and h ( R , T ) to be PF-rings and PP-rings. We also give some examples of PP-rings and PF-rings via the rings H ( R , T ) and h ( R , T ) . Full article
(This article belongs to the Special Issue Algebra and Discrete Mathematics)
18 pages, 3890 KB  
Article
Development of a PET Scanner for Simultaneously Imaging Small Animals with MRI and PET
by Christopher J Thompson, Andrew L Goertzen, Jonathan D Thiessen, Daryl Bishop, Greg Stortz, Piotr Kozlowski, Fabrice Retière, Xuezhu Zhang and Vesna Sossi
Sensors 2014, 14(8), 14654-14671; https://doi.org/10.3390/s140814654 - 12 Aug 2014
Cited by 23 | Viewed by 9677
Abstract
Recently, positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of cancer. Combined PET and X-ray computed tomography (PET-CT) scanners are now the modality of choice in cancer treatment planning. More recently, the combination of PET and [...] Read more.
Recently, positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of cancer. Combined PET and X-ray computed tomography (PET-CT) scanners are now the modality of choice in cancer treatment planning. More recently, the combination of PET and magnetic resonance imaging (MRI) is being explored in many sites. Combining PET and MRI has presented many challenges since the photo-multiplier tubes (PMT) in PET do not function in high magnetic fields, and conventional PET detectors distort MRI images. Solid state light sensors like avalanche photo-diodes (APDs) and more recently silicon photo-multipliers (SiPMs) are much less sensitive to magnetic fields thus easing the compatibility issues. This paper presents the results of a group of Canadian scientists who are developing a PET detector ring which fits inside a high field small animal MRI scanner with the goal of providing simultaneous PET and MRI images of small rodents used in pre-clinical medical research. We discuss the evolution of both the crystal blocks (which detect annihilation photons from positron decay) and the SiPM array performance in the last four years which together combine to deliver significant system performance in terms of speed, energy and timing resolution. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors in Canada 2014)
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