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1.
Numerical semigroup rings are investigated from the relative viewpoint. It is known that algebraic properties such as singularities of a numerical semigroup ring are properties of a flat numerical semigroup algebra. In this paper, we show that arithmetic and set-theoretic properties of a numerical semigroup ring are properties of an equi-gcd numerical semigroup algebra.
相似文献2.
3.
Petra Krystek Jutta Tentschert Yacine Nia Benedicte Trouiller Laurent Noël Mario E. Goetz Arnaud Papin Andreas Luch Thierry Guérin Wim H. de Jong 《Analytical and bioanalytical chemistry》2014,406(16):3853-3861
Nanosized titanium dioxide (TiO2) is one of the most interesting and valuable nanomaterials for the construction industry but also in health care applications, food, and consumer goods, e.g., cosmetics. Therefore, the properties associated with this material are described in detail. Despite its widespread use, the analytical determination and characterization of nanosized metal oxides is not as straightforward as the comparatively easy-to-detect metallic nanoparticles (e.g., silver or gold). This study presents the method development and the results of the determination of tissue titanium (Ti) levels after treatment of rats with the nanosized TiO2. Total Ti levels were chosen to evaluate the presence and distribution of TiO2 nanoparticles. A procedure consisting of incubation with a mixture of nitric acid (HNO3) and hydrofluoric acid (HF), and heating was developed to digest tissues and TiO2 nanomaterials in order to determine the total Ti content by inductively coupled plasma mass spectrometry (ICPMS). For the inter-laboratory comparison, altogether four laboratories analyzed the same samples upon digestion using the available ICPMS equipment. A major premise for any toxicokinetic study is the possibility to detect the chemical under investigation in biological samples (tissues). So, the study has to be performed with a dose high enough to allow for subsequent tissue level measurement of the chemical under investigation. On the other hand, dose of the chemical applied should not induce over toxicity in the animal as this may affect its absorption, distribution, metabolism, and excretion. To determine a non-toxic TiO2 dosage, an acute toxicity study in rats was performed, and the organs obtained were evaluated for the presence of Ti by ICPMS. Despite the differences in methodology and independent of the sample preparation and the ICPMS equipment used, the results obtained for samples with Ti concentrations >4 μg Ti/g tissue agreed well. Figure
Major Ti concentrations in micrograms per gram of organ as determined by different laboratories. 相似文献
4.
Partovi MH 《Physical review letters》2002,89(14):144101
A Hamilton-Jacobi formulation of the Lyapunov spectrum and Kolmogorov-Sinai (KS) entropy is developed. It is numerically efficient and reveals a close relation between the KS invariant and the classical action. This formulation is extended to the quantum domain using the Madelung-Bohm orbits associated with the Schroedinger equation. The resulting quantum KS invariant for a given orbit equals the mean decay rate of the probability density along the orbit, while its ensemble average measures the mean growth rate of configuration-space information for the quantum system. 相似文献
5.
Blue vitriol (copper(II) sulfate pentahydrate), CuSO4·5H2O has been chosen and investigated for its effectiveness as a flame-retardant, when impregnated into cotton fabric (cotton
with a plain structure; woven 180 g m−2, with 22 numbers of yarns per 10 mm). Using the vertical flame test, the extent of resistance to burning of the specimens
has been determined. The impregnation was accomplished via dipping and stirring of bone-dried, weighed fabrics into the individual
and suitable concentrations of the salt at room temperature. Afterwards the samples were squeeze rolled and dried horizontally
at 110°C for 30 min in an oven and cooled in a desiccator and reweighed with an analytical precision. They were then kept
under ordinary conditions overnight prior the fulfillment of the vertical flame test. The efficient quantities of the aforesaid
salt expressed in g per 100 g dry fabric have been determined in an average figure of 12.75%. Estimation of uniformity in
a selected sample was carried out via a spectrophotometer and results are in favor of the heterogeneous distribution of the
salt in the fabric’s middle sectors. However initial and final parts of specimen showed to be rather uniformed. Thermogravimetric
analysis of the pure cotton and the treated ones with insufficient and effective amounts of the salt were fulfilled and their
thermograms were compared and commented. The results obtained for the effect of copper(II) sulfate comply with ‘The Dust or
Wall Effect Theory’. This action is also assigned to the condensed phase retardation. 相似文献
6.
A novel titania sol-gel coating, including tetrabutyl orthototitanat (TBOT) as initial alkoxide, triethanolamine (TEA) as stabilizer, nitric acid as acid catalyst, and polyethylene glycol (PEG, 6000) as binder was prepared for the first time on an anodized aluminium wire and subsequently applied to headspace solid phase microextraction (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEX) with gas chromatography flame ionization detection (GC-FID). The analytical characteristics of the proposed porous titania sol-gel derived TBOT/PEG/TEA (41.6:16.0:42.4) fiber were comparable with reported fibers. The extraction temperature, extraction time, effect of salt addition, desorption temperature and desorption time were optimized. Under the optimized conditions and for all BTEX components, the linearity was from 20 to 800 μg L−1, the RSD was below 8.2% and limit of detections (LODs) were between 5.4 and 14.8 μg L−1. The recovery values were from 86.7% to 94.2% in water samples. The proposed HS-SPME-GC-FID method was successfully applied for the analysis of BTEX compounds from petrochemical wastewater samples. 相似文献
7.
Abolghasem Davoodnia Mehdi Bakavoli Raheleh Moloudi Niloofar Tavakoli-Hoseini Maryam Khashi 《Monatshefte für Chemie / Chemical Monthly》2010,122(3):867-870
Abstract
A simple, efficient, and green method for synthesis of 2,4,6-triarylpyridines by one-pot three-component reaction of acetophenones, aryl aldehydes, and ammonium acetate using 3-methyl-1-(4-sulfonylbutyl)imidazolium hydrogen sulfate [HO3S(CH2)4MIM][HSO4], a Br?nsted-acidic ionic liquid, as an effective and reusable catalyst under solvent-free conditions is described. This method has several advantages, for example simple procedure with an easy work-up, shorter reaction times, and high yields. 相似文献8.
We study arithmetic properties of tangent cones associated to large families of monomial curves obtained by gluing. In particular, we characterize their Cohen-Macaulay and Gorenstein properties and prove that they have non-decreasing Hilbert functions. The results come from a careful analysis of some special Apéry sets of the numerical semigroups obtained by gluing under a condition that we call specific gluing. As a consequence, we complete and extend the results proved by Arslan et al. (in Proc. Am. Math. Soc. 137:2225–2232, 2009) about nice gluings by using different techniques. Our results also allow to prove that for a given numerical semigroup with a non-decreasing Hilbert function and an integer q>1, all extensions of it by q, except a finite number, have non-decreasing Hibert functions. 相似文献
9.
Composite of conducting polyaniline-isobutylated urea formaldehyde: Preparation and characterization
Bakhshali Massoumi Raheleh Magssoudi Elmira Kashani Ali Akbar Entezami 《Polymer Science Series A》2011,53(8):727-732
Composite of conductive polyaniline-isobutylated urea formaldehyde have been prepared by chemical oxidative emulsion polymerization
of aniline in the presence of isobutylated urea formaldehyde resin (BUFR) in toluene-water solvents at room temperature. The
mass loading of polyaniline was controlled by varying the BUFR/aniline charging ratio as well as oxidant (ammonium persulfate)/aniline
molar ratio. Some factors capable of affecting the yield and conductivity of composite, such as amount of the oxidant, type
of the dispersants (span-80 and span-20), and amount of resin and organic acid (para-toluene sulfonic acid) were investigated.
The prepared composites were characterized by FTIR spectroscopy and scanning electron microscopy (SEM). 相似文献
10.
We describe the catalytic activity of the first chimeric ligase containing a foldameric sequence of β- and γ-amino acids. The chimeric backbone provides for the spatial arrangement of all functional groups involved in the formation of the catalytic site to allow efficient catalysis to take place. Our finding indicates significant progress in the field of functionally active artificial motifs. 相似文献