Recent developments in the synthesis of 11β-aryl-estrone derivatives

An industrial synthesis of 11β-aryl-estrone derivatives is described, based on the 1,4-addition of the aryl side-chain, as a cuprate, on to a mixture of allylic 5(10) alpha and beta epoxides, followed by hydrolysis and subsequent aromatization.     

The unexpected reactivity of Zeise's anion in strong basic medium discloses new substitution patterns at the platinum centre

Zeise's anion in strongly basic hydroxylated solvents undergoes unprecedented nucleophilic addition of OR- (R = H, Me, Et) to the eta2-ethene giving trans-[PtCl2(eta1-C2H4OR)(OR)]2- which readily reacts with bidentate nitrogen donors N-N to give Cl- and OR- substitution and formation of [PtCl(CH2CH2OR)(N-N)]. Protonolysis of this stable organometallic species offers a versatile route to cationic [PtCl(eta2-C2H4)(N-N)]+ complexes.     

1-Arylsulfonylamino-1,2,3-triazole derivatives from functionalyzed 1,2-cyclohexanediones

The heterocyclization reaction of arylsulfonylhydrazones from alkyl substituted 1,2-cyclohexanediones is sensitive to the steric requirements of the alkyl groups. A mechanism for the cyclization in acidic medium is also reported.     

Branched spines and contact structures on 3-manifolds

We introduce and analyze the characteristic foliation induced by a contact structure on a branched surface, in particular a branched standard spine of a 3-manifold. We extend to (fairly general) singular foliations of branched surfaces the local existence and uniqueness results which hold for genuine surfaces. Moreover we show that global uniqueness holds when restricting to tight structures. We establish branched versions of the elimination lemma. We prove a smooth version of the Gillman-Rolfsen PL-embedding theorem, deducing that branched spines can be used to construct contact structures in a given homotopy class of plane fields. Entrata in Redazione il 6 novembre 1998.     

Oxidative dissolution of chalcopyrite by Acidithiobacillus ferrooxidans analyzed by electrochemical impedance spectroscopy and atomic force microscopy

The microbiological leaching of chalcopyrite (CuFeS(2)) is of great interest because of its potential application to many CuFeS(2)-rich ore materials. However, the efficiency of the microbiological process is very limited because this mineral is one of the most refractory to bacterial attack. Knowledge of bacterial role during chalcopyrite oxidation is very important in order to improve the efficiency of bioleaching operation. The oxidative dissolution of a massive chalcopyrite electrode by Acidithiobacillus ferrooxidans was evaluated by electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). A massive chalcopyrite electrode was utilized in a Tait-type electrochemical cell in acid medium for different immersion times in the presence or absence of bacterium. The differences observed in the impedance diagrams were correlated with the adhesion process of bacteria on the mineral surface.     

Physico-chemical behaviour of sulpha drugs: VI. Electrochemical behaviour and electronic structure of sulphonamide derivatives

The electrochemical reduction of ØSO₂NH₂ and its ortho, para and meta amino derivatives was examined in aprotic medium (CH₃CN) with varying experimental conditions, i.e. drop time, concentration and temperature. It has been shown that the reduction process is irreversible and controlled by diffusion at small values of concentration and low drop times, while the whole process is controlled by an adsorption step at larger values of concentration and drop times. The reduction mechanism, proposed by Horner for sulphonamides of the type XØSO₂NR₁R₂, was confirmed and shown always to involve the S-N bond cleavage. Half-wave potentials and electrokinetic parameters were correlated with some theoretical and experimental structural indexes. Even if the correlation is fairly good and confirms the validity of the theoretical model assumed, it does not enable the pharmacological behaviour of the three isomers to be differentiated.     

The experimental design approach to the optimization of a simple quick easy cheap effective rugged and safe method for the analysis of phytoestrogens in complex soy‐based food

The present paper deals with the multivariate optimization of an extraction‐purification strategy for the determination of phytoestrogens (daidzein, genistein, coumestrol, formononetin, and biochanin A) in soy‐based meat substitutes by high performance liquid chromatography with tandem mass spectrometry. For a reliable quantitation of these new concerning compounds in such a complex matrix, recovery and matrix effect must be carefully evaluated. Therefore, two sequential experimental designs were used to optimize the sample‐pretreatment of soy‐based burgers: the chosen technique was the quick, easy, cheap, effective, rugged and safe methodology, which does not require any particular facility or instrumentation. Thanks to the first screening design (Plackett‐Burman), the significant factors influencing the studied responses were identified and further investigated through a response surface design (Box‐Behnken). The optimal values of the variables (volume of extraction solvent mix/sample mass ratio and two clean‐up sorbents) led to quantitative recoveries (97–104%) and low ion suppression (matrix effect 60–93%) for all analytes. This optimized method was characterized by low detection limits (0.2–1.5 ng/g) and excellent intraday precision (RSD 2–4%). It was applied to the determination of the considered compounds in several soy‐burgers from the Italian market, detecting low ng/g levels (up to 40 ng/g) of coumestrol, formononetin, and biochanin A, and high concentrations (7.9–78 µg/g) of genistein and daidzein.     

Application of ray-path geometry modification to the design of a collimating structure for LEDs

We investigate a system that is able to trace the ray path we decided previously, in particular, we would like to change a cylindrical raypath into a plane one after a given coordinate of the propagation axis. The technique we used is completely general, so we can calculate every kind of system to move some rays path in another one we want.