Crystallographic report: Bis{µ‐[O‐cyclopentyl(4‐methoxyphenyl)dithiophosphonato]1κ:S,2κ:S‐[O‐cyclopentyl(4‐methoxyphenyl)dithiophosphonato]‐1κ2S,S′}dicadmium(II)

The centrosymmetric title compound, [Cd₂{CH₃OC₆H₄P(OC₅H₉)S₂}₄], features an eight‐membered [? Cd? S? P? S? ]₂ ring owing to the presence of bridging dithiolate ligands. Tetrahedral coordination geometries for cadmium are completed by chelating ligands. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of cold work on the dissolution kinetics in the precipitating Al-2 wt% Mg alloy

The fracture stress _f was taken to assess the mechanism of dissolution of the -phase in the Al-2 wt% Mg alloy. The role of pre-cold working the polycrystalline samples was investigated. The dissolution of the -phase was carried out at different temperatures. The relation between the fracture stress and the time of dissolution showed peaky curves. The rise of _f towards a maximum was attributed to the progressive dissolution of the precipitates. The position of the peak was found to shift towards lower times of dissolution with the increase of the dissolution temperature or the increase of the pre-cold work. Considering the peak position indicative of a certain degree of dissolution, equivalent times and temperatures of the dissolution mechanism were thus found and the activation energy was calculated. Pre-cold working the samples before the dissolution act decreased the activation energy responsible for the process from 1·95×10^–19 J to about 0·48× 10^–19 J. The initial drop in _f observed for heavily cold worked samples pointed towards the possible effect of excess vacancies created by cold work.The authors are really grateful for the enlightening discussions with Prof. R. Kamel.     

Effects of Microstructural Defects on Ion-Irradiated Type-316 Stainless Steel

Microstructure defects play a very important role in the swelling of irradiated stainless steel. This work is a parametric study of the effects of microstructural defects on the swelling of ion-irradiated steel. For simplicity, vacancy loop effects were neglected. Cold working was found to play a complicated role in the swelling behavior. On one hand, it increase the bias to interstitial absorption due to the increase in dislocation density. On the other hand, it decreases the total flux of point defects to voids by the decrease of the point defect concentrations. Grain size has also a strong effect on swelling. It was found that large gain sizes produces higher swelling and vise versa, i.e. the larger the surface of grain boundaries the less the irradiation-produced swelling. Similar effects were found for precipitates.     

Commutativity theorems for s-unital rings with constraints on commutators

Let R be an associative s-unital ring with the polynomial identity \( y^{s}[x^{n},y]=\pm [x,y^{m}]x^t\) or \( y^{s}[x^{n},y]=\pm x^{t}[x,y^{m}]\) , where m, n, s and t are given non-negative integers such that m > 0 or n > 0 and m ≠ n if s = m ? 1 and t = n ? 1. Using similar methods as in our recent papers [1] and [2], we prove here the commutativity of R for various values of m, n, s and t, under appropriate constraints on torsion of commutators.     

Comparison of Boolean algebras

In this work, some results related to superatomic Boolean interval algebras are presented, and proved in a topological way. Let x be an uncountable cardinal. To each I x, we can associate a superatomic interval Boolean algebra B _I of cardinality x in such a way that the following properties are equivalent: (i) I I x, (ii) B _I is a quotient algebra of B _J, and (iii) there is an homomorphism f from B _J into B _I such that for every atom b of B _I, there is an atom a of B _J satisfying f(a)=b. As a corollary, there are 2 ^x isomorphism types of superatomic interval Boolean algebras of cardinality x. This case is quite different from the countable one.     

Strong electromagnetic field localization near the surface of hemicylindrical particles

We theoretically study the forward and backward plane wave illuminations of hemicylindrical dielectric particles with different radii and refractive indices. Near field effects providing strong field enhancement and narrow beam width are obtained from hemicylindrical particles, which can be associated with whispering gallery modes (WGMs) and photonic nano-jets (PNJs). It should be noted that existence of PNJ and WGM effects depending on forward/backward light illuminations is studied for the first time in all-dielectric hemicylindrical particles. Compared to dielectric cylinders, hemicylindrical aided PNJs show relatively small influences of WGM regime, when exists, to PNJ behavior. Under the backward excitation, on the other hand, typical nano-jet is produced. The designed hemicylindrical structure could be implemented in high-resolution optical imaging and sensing applications.     

An unsteady thermal investigation of a wetted longitudinal porous fin of different profiles

Journal of Thermal Analysis and Calorimetry - The unsteady thermal behavior of a porous longitudinal fin in a fully wet circumstance in the existence of convection as well as radiation effect is...     

Mukaiyama–Michael Reactions with trans‐2,5‐Diarylpyrrolidine Catalysts: Enantioselectivity Arises from Attractive Noncovalent Interactions,Not from Steric Hindrance

The scope of the enantioselective Mukaiyama–Michael reactions catalyzed by trans‐2,5‐diphenylpyrrolidine has been expanded to include both α‐ and β‐substituted enals. However, the rationalization of the observed enantioselectivity is far from obvious since the catalyst is not very sterically hindered. DFT calculations were carried out to rationalize the observed stereoselectivities. Transition states of the C?C bond formation between iminium intermediates and silyloxyfurans were located and their relative energies were used to estimate the stereoselectivity data. We find excellent agreement between the predicted and observed stereoselectivities. The analysis of intermolecular forces reveals that the enantioselectivity is mostly due to stabilizing noncovalent interactions between the reacting partners, not due to steric hindrance. The role of attractive noncovalent interactions in enantioselective catalysis may be underappreciated.     

Antioxidant,Antimicrobial, and Insecticidal Properties of a Chemically Characterized Essential Oil from the Leaves of Dittrichia viscosa L.

Since some synthetic insecticides cause damage to human health, compounds in plants can be viable alternatives to conventional synthetic pesticides. Dittrichia viscosa L. is a perennial Mediterranean plant known to possess biological activities, including insecticidal properties. The chemical composition of an essential oil (EOD) from D. viscosa, as well as its antioxidant, antimicrobial, and insecticidal effects on the cowpea weevil (Callosobruchus maculatus) were determined. Forty-one volatile compounds were identified in EOD, which accounted for 97.5% of its constituents. Bornyl acetate (41%) was a major compound, followed by borneol (9.3%), α-amorphene (6.6%), and caryophyllene oxide (5.7%). EOD exhibited significant antioxidant activity in all tests performed, with an IC₅₀ of 1.30 ± 0.05 mg/mL in the DPPH test and an EC₅₀ equal to 36.0 ± 2.5 mg/mL in the FRAP assay. In the phosphor-molybdenum test, EOD results ranged from 39.81 ± 0.7 to 192.1 ± 0.8 mg AAE/g E. EOD was active on E. coli (9.5 ± 0.5 mm), S. aureus (31.0 ± 1.5 mm), C. albicans (20.4 ± 0.5 mm), and S. cerevisiae (28.0 ± 1.0 mm), with MICs ranging from 0.1 mg/mL to 3.3 mg/mL. We found that 1 µL of EOD caused 97.5 ± 5.0% insect mortality after 96 h in the inhalation test and 60.0 ± 8.3% in the ingestion assay. The median lethal concentration (LC₅₀) was 7.8 ± 0.3 μL EO/L, while the effective concentration in the ingestion test (LC₅₀) was 15.0 ± 2.1 μL EO/L. We found that 20 µL of EOD caused a reduction of more than 91% of C. maculatus laid eggs.