Magnetic properties and DMRG modeling of the 1D bimetallic thiocyanate bridged compound {(CuL1)[Co(NCS)4]} (L1 = N-rac-5,12-Me2-[14]-4,11-dieneN4)

The magnetic properties of the bimetallic compound {(CuL₁)[Co(NCS)₄]}, where L₁ = N-rac-5,12-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene have been numerically analysed on the basis of the anisotropic Heisenberg spin-chain model. In the model the single-ion anisotropy of the Co(II) ions is taken into account and the interchain interactions are neglected. The thermodynamic properties are calculated using the DMRG technique adapted to the molecular-based chains for the first time which is reliable in the entire temperature region. The high accuracy results of our simulations have been successfully fitted to the corresponding experimental susceptibility and magnetization data measured for the powder sample and the model parameters (the exchange coupling J, the absolute value of the anisotropy constant D, the anisotropic g factors) have been estimated. The quantum model parameters are consistent with the previous findings, although the ferromagnetic interactions between Cu(II) and Co(II) ions through the thiocyanate bridge are somewhat weaker (J/k_B = 1.0 ± 0.1) than found before.     

BF3·OEt2-promoted reaction of isocyanides with o-aminobenzophenones

Aliphatic isocyanides react with o-aminobenzophenones in dichloromethane under Lewis acid catalysis at ambient temperature to give, unexpectedly, 4-aryl-4-hydroxy-3,4-dihydroquinazolines in good to excellent yields. The outcome of the reaction is rationalized by a skeletal rearrangement of the initially formed ‘intramolecular Passerini’ reaction products, 2-amino-3-hydroxy-3-aryl-3H-indoles.     

Stereoselective synthesis of novel functionalized cyclohexanone derivatives via the condensation of aromatic aldehydes with acetoacetamide and the influence of the ortho-effect and autocondensation

A simple, inexpensive and stereoselective synthesis of novel functionalized cyclohexanone derivatives via the reaction of acetoacetamide with aromatic aldehydes in ethanol at room temperature is described. Additionally, the presence of substituents such as NO₂ and Cl in the ortho-position of the aldehyde aromatic ring resulted in the formation of novel piperidines. The use of Lewis acids such as iron(III) chloride and bismuth(III) nitrate as catalysts led to autocondensation of acetoacetamide and the formation of 2,4-dimethyl-6-oxo-1,6-dihydropyridine-3-carboxamide.     

Hydration and hardening processes of Portland cements obtained from clinkers mineralized with fluoride and oxides

The hydration and hardening processes of Portland cements prepared from clinkers mineralized with sodium fluoride and/or oxides (SnO₂ or CuO) was studied. Type I cements (CEM I) were prepared by grinding with gypsum (5%) of clinkers obtained by the burning of an industrial raw mix with different mineralizers: sodium fluoride, oxides (CuO and SnO₂) or mixtures of sodium fluoride and oxide (NaF + CuO or NaF + SnO₂). The influence of foreign ions on the clinker morphology was assessed by scanning electronic microscopy (SEM) and energy dispersive X-ray spectrometry (EDX). The hydration processes of modified cements were examined by X-ray diffraction analysis (XRD) and thermal analysis techniques (TG and DTA). The main properties of the cements, i.e., flexural and compressive strengths, setting time, and soundness were also determined. A good correlation between the chemically bound water or portlandite content in pastes hydrated 2–28 days and compressive strength developed by mortars was observed. The influence of mineralizers on the kinetic of hydration processes and main properties of cements is different—0.5% NaF and 0.5% SnO₂ and their mixture increase the rate of cement hydration and hardening processes, opposite to 0.5% CuO that reduce the rate.     

Micro-analytical and microbiological investigation of selected book papers from the nineteenth century

Books represent a very important part of the cultural heritage, due to their double characteristics: first, as a man-made material and secondly, due to the information they store. The characterization of book paper represents a very important step in developing solutions for better conservation procedures, as well as for fully understanding their provenance. The present paper describes the analytical and microbiological evaluation of a collection of books from the nineteenth century, belonging to the authors’ private collections. The samples consisted of four books printed in Romania and five printed in France. The analytical characterization was performed using optical microscopy, thermal analysis, spectroscopic methods (X-ray fluorescence, X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy), as well as by the evaluation of the degree of polymerization and the color change. The analyses were chosen in order to be either non-destructive or, at least, micro-destructive. The fungal loading determination was performed by plating the samples on the potato dextrose agar and Sabouraud with chloramphenicol agar media, for 28 days, followed by macroscopically and microscopically identification of mold species. The present study offers a complex methodology regarding the use of non- or micro-invasive techniques for evaluating the composition, state of degradation and potential risks related to microorganism colonization of paper artifacts.     

Formation of Secondary or Tertiary Aliphatic Amines in Aqueous Media

Secondary and tertiary amines can be easily obtained from primary and secondary amines, respectively, in completely aqueous media, in the presence of a bicatalytic system formed of cheap commercial aluminum (Al) powder and 5% rhodium (Rh) or ruthenium (Ru) deposed on charcoal.     

Synthesis and properties of new fullerene C60 derivatives,containing acetonide and polyol fragments

New mono- and hexa-methanofullerenes containing different number of acetonide groups are synthesized and characterized. Removing the acetonide protection leads to new chromatographically pure water-soluble polyol methanofullerenes with essentially quantitative yields.     

One-sided Perron Differential Inclusions

The main qualitative properties of the solution set of almost lower (upper) semicontinuous one-sided Perron differential inclusion with state constraints in finite dimensional spaces are studied. Using the technique introduced by Veliov (Nonlinear Anal 23:1027–1038, 1994) we give sufficient conditions for the solution map of the above state constrained differential inclusion to be continuous in the sense of Hausdorff metric. An application on the propagation of the continuity of the state constrained minimum time function associated with the nonautonomous differential inclusion and the target zero is given. Some relaxation theorems are proved, which are used afterward to derive necessary and sufficient conditions for invariance.