Search

The temperature dependent magnetization of nanocomposite alloys has been fit with a modified Handrich-Kobe equation with an asymmetric exchange fluctuation parameter combined with the Arrott-Noakes equation. The two equations of state are combined to calculate the entropy change in the magnetocaloric effect associated with the ferromagnetic to paramagnetic phase transformation. The complete fit for the M(T) of (Fe70Ni30)88Zr7B4Cu nanocomposite powder is accomplished by combining the two theories. We investigate the broadening of the second-order transition arising from asymmetric exchange parameters and resulting from the fluctuations of interatomic spacing found in an amorphous matrix and the asymmetric dependence of exchange energy on interatomic spacing. The magnetic entropy curve revealed extra broadening with a refrigeration capacity (RC) value of 135 J/kg at 5 T, which is comparable to (Fe76Cr8-xMoxCu1B15) ribbons, which have a RC value of 180 J/kg for the same applied field. Broadening of the magnetic entropy can lead to larger RC values and a wider working temperature range, making nanocomposite alloys promising for magnetocaloric applications.

The temperature dependent magnetization of nanocomposite alloys has been fit with a modified Handrich-Kobe equation with an asymmetric exchange fluctuation parameter combined with the Arrott-Noakes equation. The two equations of state are combined to calculate the entropy change in the magnetocaloric effect associated with the ferromagnetic to paramagnetic phase transformation. The complete fit for the M(T) of (Fe70Ni30)88Zr7B4Cu nanocomposite powder is accomplished by combining the two theories. We investigate the broadening of the second-order transition arising from asymmetric exchange parameters and resulting from the fluctuations of interatomic spacing found in an amorphous matrix and the asymmetric dependence of exchange energy on interatomic spacing. The magnetic entropy curve revealed extra broadening with a refrigeration capacity (RC) value of 135 J/kg at 5 T, which is comparable to (Fe76Cr8-xMoxCu1B15) ribbons, which have a RC value of 180 J/kg for the same applied field. Broadening of the magnetic entropy can lead to larger RC values and a wider working temperature range, making nanocomposite alloys promising for magnetocaloric applications.

The temperature dependent magnetization of nanocomposite alloys has been fit with a modified Handrich-Kobe equation with an asymmetric exchange fluctuation parameter combined with the Arrott-Noakes equation. The two equations of state are combined to calculate the entropy change in the magnetocaloric effect associated with the ferromagnetic to paramagnetic phase transformation. The complete fit for the M(T) of (Fe70Ni30)88Zr7B4Cu nanocomposite powder is accomplished by combining the two theories. We investigate the broadening of the second-order transition arising from asymmetric exchange parameters and resulting from the fluctuations of interatomic spacing found in an amorphous matrix and the asymmetric dependence of exchange energy on interatomic spacing. The magnetic entropy curve revealed extra broadening with a refrigeration capacity (RC) value of 135 J/kg at 5 T, which is comparable to (Fe76Cr8-xMoxCu1B15) ribbons, which have a RC value of 180 J/kg for the same applied field. Broadening of the magnetic entropy can lead to larger RC values and a wider working temperature range, making nanocomposite alloys promising for magnetocaloric applications.

The temperature dependent magnetization of nanocomposite alloys has been fit with a modified Handrich-Kobe equation with an asymmetric exchange fluctuation parameter combined with the Arrott-Noakes equation. The two equations of state are combined to calculate the entropy change in the magnetocaloric effect associated with the ferromagnetic to paramagnetic phase transformation. The complete fit for the M(T) of (Fe70Ni30)88Zr7B4Cu nanocomposite powder is accomplished by combining the two theories. We investigate the broadening of the second-order transition arising from asymmetric exchange parameters and resulting from the fluctuations of interatomic spacing found in an amorphous matrix and the asymmetric dependence of exchange energy on interatomic spacing. The magnetic entropy curve revealed extra broadening with a refrigeration capacity (RC) value of 135 J/kg at 5 T, which is comparable to (Fe76Cr8-xMoxCu1B15) ribbons, which have a RC value of 180 J/kg for the same applied field. Broadening of the magnetic entropy can lead to larger RC values and a wider working temperature range, making nanocomposite alloys promising for magnetocaloric applications.

The synthesis and antiviral activity of an original series of 6-benzoyl-benzoxazolin-2-one and 6-benzoyl-benzothiazolin-2-one derivatives are described. Several compounds were found to have a selective inhibitory activity against human cytomegalovirus (HCMV) and varicella-zoster virus (VZV) in vitro, being inactive against a variety of other DNA and RNA viruses. 6-(3-fluorobenzoyl)benzoxazolin-2-one, 6-(3-fluorobenzoyl)benzothiazolin-2-one, 6-(3-bromobenzoyl)benzothiazolin-2-one, 6-(3-iodobenzoyl)benzothiazolin-2-one, 3-methyl-6-(3-fluorobenzoyl)benzothiazolin-2-one, 3-benzyl-6-benzoyl-benzothiazolin-2-one, 3-benzyl-6-(3-fluorobenzoyl)benzothiazolin-2-one and 3-benzoyl-6-(3-fluorobenzoyl)benzothiazolin-2-one were the most active of the series against HCMV and VZV with a selectivity index (CC50/IC50) ranging from 10 to 20. They displayed similar activity against thymidine kinase competent (TK+) and deficient (TK-) VZV strains, and also proved to be active against clinical HCMV isolates that were resistant to ganciclovir (GCV). Time-of-addition experiments revealed a site of interaction with the HCMV replicative cycle that may be close or similar to that of GCV and cidofovir (HPMPC). The compounds showed poor, if any, activity against herpes simplex virus type 1 (HSV-1) and HSV-2, and were not inhibitory against human immunodeficiency virus and other DNA and RNA viruses. Therefore, these compounds may represent a novel lead for the development of specific HCMV and VZV drugs.

A series of 2(3H)-benzoxazolone and 2(3H)-benzothiazolone derivatives were synthesized and evaluated for anticonvulsant activity. The compounds were assayed, intraperitoneally in mice and per os in rats, against seizures induced by maximal electroshock (MES) and pentylenetetrazole (scMet). Neurologic deficit was evaluated by the rotarod test. The compounds were prepared to determine the relationship between the 2(3H)-benzoxazolone and 2(3H)-benzothiazolone derivatives' structures and anticonvulsant activity. Several of these compounds showed significant anticonvulsant activity. Compounds 43 and 45 were the most active of the series against MES-induced seizures with ED50 values of 8.7 and 7.6 mg/kg, respectively. Compound 45 displayed good protection against MES-induced seizures and low toxicity in rats with an oral ED50 of 18.6 mg/kg and a protective index (PI = TD50/ED50) of < 26.9. In vitro receptor binding studies revealed that compounds 43 and 45 bind to sigma 1 receptors with nanomolar affinities.

6-Acyl-2(3H)-benzoxazolone and 6-acyl-2(3H)-benzothiazolone derivatives have particularly interesting anti-inflammatory, antiepileptic, analgesic and antiviral properties. in this study, we report an original method of acylation on the 6-position of 2(3H)-benzoxazolone and 2(3H)-benzothiazolone which consists in a two-step procedure involving migration of the acyl group from the N-position to the 6-position of the heterocycle, at 165 degrees C and catalyzed by AlCl3. This new procedure was found to be more efficient with regard to the consumption of AlCl3 and the yield (76-90%) than other acylation methods previously described. (C) 1998 Elsevier Science Ltd. All rights reserved.

A series of original 2(3H)-benzoxazolone and 2(3H)-benzothiazolone derivatives were evaluated for their affinity at sigma1 and sigma2 receptor subtypes in competition binding experiments, using [3H](+)-pentazocine or [3H]1,3-di-o-tolyl-guanidine (DTG) in the presence of 100 nM (+)-N-allylnormetazocine (NANM) in guinea-pig brain membranes. Several of these derivatives showed preferential selectivity for sigma1 binding sites. Compound 1 [3-(1-piperidinoethyl)-6-propylbenzothiazolin-2-one] emerged as a potent sigma1 receptor ligand (Ki = 0.6 nM) and displayed a moderate selectivity over the sigma2 receptor subtype (Ki for sigma2/Ki for sigma1 = 29). Compounds 2 [3-(1-piperidinopropyl)-6-propanoylbenzothiazolin-2-one] and 3 [3-(1-piperidinopropyl)-6-propanoylbenzoxazolin-2-one] still showed rather high affinities for sigma1 binding sites with Ki values of 2.3 and 8.5 nM, respectively. On the contrary, they had 87- and 58-fold less affinity at sigma2 receptors, respectively. Unlike their potent affinity for sigma binding sites, these compounds had negligible affinity for mu-, delta- and kappa-opioid receptors, 5-HT2, dopamine D2, and muscarinic M2 receptors. Sigma receptor ligands may affect neuronal transmission and display, in animal models, antipsychotic, cognitive, motor, neuroprotective and anticonvulsant activity. Therefore, on the basis of these findings, these novel sigma receptor ligands were assayed, in mice, in three tests: maximal electroshock, subcutaneous pentylenetetrazol and rotarod neurotoxicity. Compound 1, administered intraperitoneally, was the most effective against maximal electroshock-induced seizures and was devoid of significant neurotoxic effects.

Synthesis of series of symmetrical benzophenone derivatives by C-alkylation reaction of 2(3H)-benzoxazolone and 2 (3H)-benzothiazolone with carbon tetrachloride in presence of AlCl3-DMF reagent is reported.

This paper reports and compares different methods to synthesize 6-benzoyl-2(3H)-benzoxazolone and 6-benzoyl-2(3H)-benzothiazolone by Fridel-Crafts acylation of 2(3H)-benzoxazolone and 2(3H)-benzothiazolone. The best method found consisted of the transposition of the N-benzoyl derivative fa the target compound, a process taking place at 160 degrees C and catalyzed by AlCl3. In these conditions, 6-benzoyl-2(3H)-benzoxazolone and 6-benzoyl-2(3H)-benzothiazolone were obtained in 80 and 85 % yield, respectively.

2(3H)-benzoxazolones or 2(3H)-benzothiazolones react at 70-75 degrees C with omega-halogenoacyl chlorides in the presence the AlCl3-DMF complex to produce the expected ketones in 55-88 % yield. Treatment of a 2(3H)-benzoxazolone or 2(3H)-benzothiazolone by 4-chlorobutyryl chloride produced an alcohol derivative, presumably via an anchimeric participation of the 6-acyl carbonyl moiety.

The Willgerodt-Kindler reaction was studied on three different model compounds (4-bromo benzaldehyde, 4-fluorobenzaldehyde, 4-methoxyacetophenone) with particular emphasis on the influence of the solvent on the yield of the reaction, Best conditions involved the use of polar aprotic solvents such as DMF. This finding was applied to the Willgerodt-Kindler reaction of two difficult substrates, i.e. 3-methyl-6-formyl-2(3H)-benzoxazolinone and 3-methyl-6-formyl-2(3H)-benzothiazolinone with various secondary amines.