Novel palladium nanoparticles supported on β‐cyclodextrin@graphene oxide as magnetically recyclable catalyst for Suzuki–Miyaura cross‐coupling reaction with two different approaches in bio‐based solvents

A novel nanocatalyst was designed and prepared. Initially, the surface of magnetic graphene oxide (M‐GO) was modified using thionyl chloride, tris(hydroxymethyl)aminomethane and acryloyl chloride as linkers which provide reactive C═C bonds for the polymerization of vinylic monomers. Separately, β‐cyclodextrin (β‐CD) was treated with acryloyl chloride to provide a modified β‐CD. Then, in the presence methylenebisacrylamide as a cross‐linker, monomers of modified β‐CD and acrylamide were polymerized on the surface of the pre‐prepared M‐GO. Finally, palladium acetate and sodium borohydride were added to this composite to afford supported palladium nanoparticles. This fabricated nanocomposite was fully characterized using various techniques. The efficiency of this easily separable and reusable heterogeneous catalyst was successfully examined in Suzuki–Miyaura cross‐coupling reactions of aryl halides and boronic acid as well as in modified Suzuki–Miyaura cross‐coupling reactions of N‐acylsuccinimides and boronic acid in green media. The results showed that the nanocatalyst was efficient in coupling reactions for direct formation of the corresponding biphenyl as well as benzophenone derivatives in green media based on bio‐based solvents. In addition, the nanocatalyst was easily separable, using an external magnet, and could be reused several times without significant loss of activity under the optimum reaction conditions.     

Validation of scanning electron microscope (SEM), energy dispersive X-ray (EDX) and gamma spectrometry to verify source nuclear material for safeguards purposes

Ten ore samples, two unpurified yellow cake samples and natural uranyl nitrate hexahydrate sample were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) method to verify source nuclear material. Samples represent source nuclear material as possible. All samples were scanned at ideal conditions; working distance = 10 mm, voltage = 30 kV, magnification value = × 100, spot size = 50 to screen samples for the presence of uranium and thorium, Also Hyper pure germanium (HPGe) gamma spectrometers were applied to estimate the uranium and thorium contents in Bq/kg (ppm). For the ore samples uranium-238 ranges from 1,049.23 Bq/kg (85.30 ppm) to 2,096.06 Bq/kg (170.41 ppm), uranium-235 ranges from 47.51 to 105.61 Bq/kg and thorium-232 ranges from 22.84 Bq/kg (5.65 ppm) to 41.78 Bq/kg (10.34 ppm). For the yellow cake samples and uranyl nitrate hexahydrate uranium-238 ranges from 42.99 Bq/kg (3.50 ppm) to 71,887.2 Bq/kg (5,844.49 ppm) and thorium-232 is 4.78 Bq/kg (1.83 ppm) and the other two samples are lower than the detection limit.     

Facile synthesis and antimicrobial evaluations of some novel pyrazolo[3,4-b]selenolo[3,2-e]pyrazines and their related heterocycles

A new series of pyrazolopyrazinoselenolotriazolopyrimidines was synthesized by a facile method based on condensation of 5-amino-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]selenolo[3,2-e]pyrazine-6-carbonitrile ( 3 ) with triethyl orthoformate followed by intramolecular cyclization with hydrazine to afford 7-amino-8-imino-3-methyl-1-phenyl-1,8-dihydro-7H-pyrazolo[3″,4″:5′,6′]pyrazino[2′,3′:4,5] selenolo[3,2-d]pyrimidine ( 5 ). The latter compound was utilized as a multipurpose precursor for the construction of other new triazoles fused to the pyrazolopyrazino- selenolopyrimidine moiety. Alternatively, acetylation and chloro-acetylation of compound 3 using acetic anhydride and chloroacetyl chloride yielded the acetyl amino 11 and chloroacetamido 12 derivatives, respectively. Compound 12 underwent nucleophilic substitution upon reaction with morpholine to provide the morpholinyl acetamide 13 . Furthermore, the pyrazolopyridoselenolopyrazine ring system 14 was synthesized by the reaction of the o-amino-carbonitrile 3 with malononitrile. Assignment of the chemical structures for the new compounds was confirmed depending on elemental and spectral techniques. On the other hand, most of the synthesized compounds revealed promising results against various bacterial and fungal strains.     

Intransitive Permutation Group with Bounded Movement

Let G be a intransitive permutation group on a set with no fixed point in ; let m, n be a positive integer and let |^g – | m, for every and g G. When G has t orbits and degree n close to [2mp/(p – 1)] + t – 1, this paper constructs such a group with m close to [n(p – 1)/2p].AMS Subject Classification: 20BXX.     

Coupled fixed point theorems for contractions in fuzzy metric spaces

In the present work, we prove a coupled fixed point theorem for contractive mappings in complete fuzzy metric spaces.     

Some results on the annihilators and attached primes of local cohomology modules

Let \((R, \mathfrak {m})\) be a local ring and M a finitely generated R-module. It is shown that if M is relative Cohen–Macaulay with respect to an ideal \(\mathfrak {a}\) of R, then \({\text {Ann}}_R(H_{\mathfrak {a}}^{{\text {cd}}(\mathfrak {a}, M)}(M))={\text {Ann}}_RM/L={\text {Ann}}_RM\) and \({\text {Ass}}_R (R/{\text {Ann}}_RM)\subseteq \{\mathfrak {p}\in {\text {Ass}}_R M|\,\mathrm{cd}(\mathfrak {a}, R/\mathfrak {p})={\text {cd}}(\mathfrak {a}, M)\},\) where L is the largest submodule of M such that \(\mathrm{cd}(\mathfrak {a}, L)< \mathrm{cd}(\mathfrak {a}, M)\). We also show that if \(H^{\dim M}_{\mathfrak {a}}(M)=0\), then \({\text {Att}}_R(H^{\dim M-1}_{\mathfrak {a}}(M))= \{\mathfrak {p}\in {\text {Supp}}(M)|\mathrm{cd}(\mathfrak {a}, R/\mathfrak {p})=\dim M-1\},\) and so the attached primes of \(H^{\dim M-1}_{\mathfrak {a}}(M)\) depend only on \({\text {Supp}}(M)\). Finally, we prove that if M is an arbitrary module (not necessarily finitely generated) over a Noetherian ring R with \(\mathrm{cd}(\mathfrak {a}, M)=\mathrm{cd}(\mathfrak {a}, R/{\text {Ann}}_RM)\), then \({\text {Att}}_R(H^{\mathrm{cd}(\mathfrak {a}, M)}_{\mathfrak {a}}(M))\subseteq \{\mathfrak {p}\in {\text {V}}({\text {Ann}}_RM)|\,\mathrm{cd}(\mathfrak {a}, R/\mathfrak {p})=\mathrm{cd}(\mathfrak {a}, M)\}.\) As a consequence of this, it is shown that if \(\dim M=\dim R\), then \({\text {Att}}_R(H^{\dim M}_{\mathfrak {a}}(M))\subseteq \{\mathfrak {p}\in {\text {Ass}}_R M|\mathrm{cd}(\mathfrak {a}, R/\mathfrak {p})=\dim M\}\).     

Acetone extracted propolis as a novel membrane and its application in phenol biosensors: the case of catechol

A novel biosensor for catechol has been constructed by immobilizing polyphenol oxidase (PPO) into acetone-extracted propolis (AEP) composite modified with gold nanoparticles (GNPs) and attached to multiwalled carbon nanotube (MWCNTs) on a gold electrode surface. The propolis for AEP was obtained from honeybee colonies. Under the optimum conditions, this method could be successfully used for the amperometric determination of catechol within a concentration range of 1 × 10^?6 to 5 × 10^?4?M, with a detection limit of 8 × 10^?7?M (S/N = 3). The effects of pH and operating potential are also explored to optimize the measurement conditions. The best response was obtained at pH?5, while an optimum ratio of signal-to-noise (S/N) was obtained at ?20?mV (versus Ag/AgCl), which was selected as the applied potential for the amperometric measurements. All subsequent experiments were performed at pH?5. Cyclic voltammetry and electrochemical impedance spectroscopy was used to characterize the PPO/CNTs/GNPs/AEP/Au biosensor. The biosensor also exhibited good selectivity, stability, and reproducibility.     

Faltings’ local–global principle for finiteness dimension of cofinite modules

Archiv der Mathematik - Let R denote a commutative Noetherian ring, $$\mathfrak {a}$$ an ideal of R, and M an $$\mathfrak {a}$$ -cofinite R-module. The purpose of this article is to show that for a...     

Weakly associated primes and primary decomposition of modules over commutative rings

Summary We characterize finitely generated Laskerian modules over a commutative ring in terms of weakly associated prime ideals.