Effects of γ-irradiation on caprolactam level from multilayer PA-6 films for food packaging: Development and validation of a gas chromatographic method

A gas chromatographic method to determine caprolactam in multilayer PA-6 films used for meat foodstuffs and cheese was developed and validated. A wide linear range (0.8–400 μg/ml), RSD4.1% and recovery higher than 90.0% were obtained for the chromatographic system, while precision and accuracy of the method showed RSD3.8%, recovery from 95.5–100.0% and LOQ of 32 μg/g. Irradiated (3, 7 and 12 kGy) and non-irradiated commercial films were analyzed. Most of them increased caprolactam levels with the increase of irradiation doses.     

Diffusion coefficients of nickel chloride in aqueous solutions of lactose at T = 298.15 K and T = 310.15 K

Binary mutual diffusion coefficients (interdiffusion coefficients) of nickel chloride in water at T = 298.15 K and T = 310.15 K, and at concentrations between (0.000 and 0.100) mol · dm^?3, using a Taylor dispersion method have been measured. These data are discussed on the basis of the Onsager–Fuoss and Pikal models. The equivalent conductance at infinitesimal concentration of the nickel ion in these solutions at T = 310.15 K has been estimated using these results. Through the same technique, ternary mutual diffusion coefficients (D₁₁, D₂₂, D₁₂, and D₂₁) for aqueous solutions containing NiCl₂ and lactose, at T = 298.15 K and T = 310.15 K, and at different carrier concentrations were also measured. These data permit us to have a better understanding of the structure of these systems and the thermodynamic behaviour of NiCl₂ in different media.     

Molecular energetics of alkyl substituted pyridine <Emphasis Type="Italic">N</Emphasis>-oxides

The standard (p° = 0.1 MPa) energies of combustion in oxygen, at T = 298.15 K, for the solid compounds 2-methylpyridine-N-oxide (2-MePyNO), 3-methylpyridine-N-oxide (3-MePyNO) and 3,5-dimethylpyridine-N-oxide (3,5-DMePyNO) were measured by static-bomb calorimetry, from which the respective standard molar enthalpies of formation in the condensed phase were derived. The standard molar enthalpies of sublimation, at the same temperature, were measured by Calvet microcalorimetry. From the standard molar enthalpy of formation in gaseous phase, the molar dissociation enthalpies of the N–O bonds were derived, and compared with values of the dissociation enthalpies of other N–O bonds available for other pyridine-N-oxide derivatives.     

Solid phase microextraction associated with microwave assisted extraction of food products

Veltol® (2-methyl 3-hydroxy 4-pyrone) and Veltol-Plus® (2-ethyl 3-hydroxy 4-pyrone) are patented flavor ingredients in food products. Only Veltol® can occur naturally, but both Veltol® and Veltol-Plus® are often added to food products. In order to monitor the use of these compounds in food products, lower detection limits were needed. The Solid Phase Microextraction (SPME) technique for beverages and SPME coupled with Microwave Assisted Extraction (MAE) for solid food samples were studied. The influence of the pH, salt content, SPME adsorption time, GC inlet conditions, and the conditioning of the SPME fiber were investigated. Different food products were tested including coffee, beverages, chewing gums and potato chips. The coupled MAE and SPME shows good results for solid food samples. The reproducibility of the technique was less than 13%RSD and the detection limit was 10 ppb for Veltol® and 2 ppb for Veltol-Plus® using the SIM mode in GC/MS. The technique also shows good selectivity for the target compounds investigated in different food samples.     

Crystal Structure and Synthesis of Three New Steroidal Derivatives as Antiandrogens

Abstract  

The structures of 3β-cyclobutyl carbonyloxy-5-androsten-17-one (C₂₄H₃₄O₃), compound 1; 3β-cyclopentyl carbonyloxy-5-androsten-17-one (C₂₅H₃₆O₃), compound 2; and 3β-cyclohexyl carbonyloxy-5-androsten-17-one (C₂₆H₃₈O₃) compound 3 were established by spectral and X-ray diffraction studies. Steroidal derivatives 1–3 exhibited a high antiandrogenic effect and could be considered as potential drugs for the treatment of prostate cancer. Compound 1 crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters a = 6.618(2), β = 14.167(3), c = 22.329(5) ?, Z = 4. Compound 2 crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters a = 6.631(2), b = 13.865(4), c = 23.952(7) ?, Z = 4. Compound 3 crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters a = 6.6100(9), b = 13.896(2), c = 24.491(3) ?, Z = 4. All three structures (1–3) were solved by direct methods and refined to R = 0.0708, 0.0750 and 0.0496, respectively. For compound 2, there is positional disorder of the side chain at C3. All the rings of both steroid skeletons are trans connected. For structures 1–3, the six-membered rings A, B and C have a deformed chair, half chair and deformed chair conformations. The five-membered rings D adopt an intermediate envelope and half-chair conformations. For structure 2, the five-membered rings E and EA have a deformed envelope and an intermediate envelope and half-chair conformations, respectively. For structure 3, the six-membered ring E adopts a deformed chair conformation. Cohesion of the crystals can be attributed to van der Waals and weak C–H⋯O interactions.     

Efficient palladium-catalyzed cross-coupling of highly acidic substrates, nitroacetates

Palladium-catalyzed cross-coupling conditions were developed that efficiently afford 2-aryl-2-nitroacetates from aryl bromides and the very acidic nitroacetates.     

Palladium-catalyzed nitromethylation of aryl halides: an orthogonal formylation equivalent

An efficient cross-coupling reaction of aryl halides and nitromethane was developed with the use of parallel microscale experimentation. The arylnitromethane products are precursors for numerous useful synthetic products. An efficient method for their direct conversion to the corresponding oximes and aldehydes in a one-pot operation has been discovered. The process exploits inexpensive nitromethane as a carbonyl equivalent, providing a mild and convenient formylation method that is compatible with many functional groups.     

Mechanical and Biological Performances of New Scaffolds Made of Collagen Hydrogels and Fibroin Microfibers for Vascular Tissue Engineering

A microstructured composite material made of collagen hydrogel (matrix) and silk fibroin microfibers (randomly oriented reinforcing fibers) is investigated in order to conjugate the mechanical resistance of fibroin with the suitable biological performance of collagen to design new scaffolds for vascular tissue engineering. Results show that fibroin microfibers and collagen fibrils have suitable interfacial adhesion, and the scaffold exhibits improved mechanical properties if compared with a pure collagen hydrogel. Furthermore, the overall biological performance is improved.