New N-aryloxy-phthalimide derivatives. Synthesis,physico-chemical properties,and QSPR studies

Starting from N-hydroxyphthalimide 1 and the reactive fluoro- or chloro-nitroaryl derivatives 2, 3 and 4a-e (2-chloro-3,5-dinitropyridine; 3, NBD-chloride; 4a, 1-fluoro-2,4-dinitrobenzene; 4b, picryl chloride; 4c, 4-chloro-3,5-dinitrobenzotrifluoride; 4d, 2-chloro-3,5- dinitrobenzotrifluoride; 4e, 4-chloro-3,5-dinitrobenzoic acid) the corresponding N-(2-nitroaryloxy)-phthalimide derivatives 5a-e, or 6 and 7 were obtained and characterized by IR, UV-Vis ¹H-NMR and ¹³C-NMR spectroscopy. The TLC behavior and the hydrophobicity of these derivatives have been experimentally evaluated by R_M0 parameters (using RP-TLC). The experimental R_M0 parameters were compared with the calculated partition coefficient, log P. A QSPR study was also performed to establish possible correlations between the structure and physical properties (λ_max and R_M0) of compounds 5a-e, 6, and 7.      

<Emphasis Type="Italic">N</Emphasis>-Alkoxy-3,5-dinitro-4-aminobenzoic acid derivatives with controlled physico-chemical properties

Starting from 4-chloro-3,5-dinitrobenzoic acid 1, compounds 2–10 (N-alkoxy-3,5-dinitro-4-aminobenzoic acid esters where alkoxy stands for methoxy, carboxymethoxy, triphenylmethoxy, or corresponding amides) have been obtained, from which compounds 3–5 and 7–10 are new, and for the known compounds 2 and 6 the synthetic procedure has been improved. The new derivatives have been characterized by appropriate means (IR, UV–Vis, ¹H- and ¹³C-NMR, fluorescence) and their properties were studied. Thus, depending on their structure, the compounds have acid properties, fluorescence and complexing properties with alkaline cations.     

Pulsed and continuous wave acrylic acid radio frequency plasma deposits: plasma and surface chemistry

Plasma polymers have been formed from acrylic acid using a pulsed power source. An on-pulse duration of 100 micros was used with a range of discharge off-times between 0 (continuous wave) and 20,000 micros. X-ray photoelectron spectroscopy (XPS) has been used in combination with trifluoroethanol (TFE) derivatization to quantify the surface concentration of the carboxylic acid functionality in the deposit. Retention of this functionality from the monomer varied from 2% to 65%. When input power was expressed as the time-averaged energy per monomer molecule, E(mean), the deposit chemistry achieved could be described using a single relationship for all deposition conditions. Deposition rates were monitored using a quartz crystal microbalance, which revealed a range from 20 to 200 microg m(-2) s(-1), and these fell as COOH functional retention increased. The flow rate was found to be the major determinant of the deposition rate, rather than being uniquely defined by E(mean), connected to the rate at which fresh monomer enters the system in the monomer deficient regime. The neutral species were collected in a time-averaged manner. As the energy delivered per molecule in the system (E(mean)) decreased, the amount of intact monomer increased, with the average neutral mass approaching 72 amu as E(mean) tends to zero. No neutral oligomeric species were detected. Langmuir probes have been used to determine the temporal evolution of the density and temperature of the electrons in the plasma and the plasma potential adjacent to the depositing film. It has been found that even 500 micros into the afterglow period that ionic densities are still significant, 5-10% of the on-time density, and that ion accelerating sheath potentials fall from 40 V in the on-time to a few volts in the off-time. We have made the first detailed, time- and energy-resolved mass spectrometry measurements in depositing acrylic acid plasma. These have allowed us to identify and quantify the positive ion species in the acrylic acid plasma during both the on- and the off- periods. The relative intensities of oligomeric species of the type [nM + H]+ as large as n = 3 were observed to increase in the off-time suggesting vapor phase polymerization after power input to the plasma was ceased. The energy distribution functions of these ions demonstrated that they were produced in the plasma in both the on- and the off-times. This remarkable observation contradicts the assumptions usually made when speculating on pulsed plasma that ions have very short lifetimes, although it is anticipated that radicals still have significantly longer lifetimes, estimated from calculation to be in excess of 1 ms. The increase in average positive ion mass during the off-period can be related to the lower mobility of the heavier components, reducing their relative loss to surfaces, and the polymer chain growth in the gas phase due to the ion-neutral collisions. The implications of these observations are discussed in light of polymerization mechanisms proposed from continuous acrylic acid and millisecond pulsing plasmas.     

O-Methyloximes of Testosterone and of 17α-Methyltestosterone: TLC and QSPR Study of RF Values

JPC – Journal of Planar Chromatography – Modern TLC - The Z (1b and 2b, respectively) and E diastereomers (1c and 2c, respectively) of the O-methyloximes of testosterone (1a) and...     

Production, chemical and isotopic separation of the178m2Hf high-spin isomer

The ^178m2Hf with its long-lived (T_1/2=31 y), high-spin I^π = 16⁺, isomeric state, is a challenge for new and exotic nuclear physics studies. The ^178m2Hf isomer has been produced in microweight quantities using the ¹⁷⁶Yb(α,2n) nuclear reaction, by irradiation with a high-intensity beam using the U-200 cyclotron in Dubna. Radiochemistry and mass separation methods have been developed, with the aim to separate and purify the produced Hf material. Thin targets of isomeric hafnium-178 on carbon backings have been prepared and used in experiments with neutron, proton and deuteron beams. This revised version was published online in August 2006 with corrections to the Cover Date.     

57Fe Mössbauer spectroscopy on disordered crystalline media with Ca-gallogermanate type structure. II. Below the magnetic ordering temperature

Magnetic phase transitions in disordered crystalline iron germanates of the type Sr₂LnFe₃Ge₃O₁₄ (Ln=La; Nd) were observed at low temperatures by means of⁵⁷Fe Mössbauer spectroscopy. The hyperfine interaction of Fe³⁺ magnetic moments ordered in one octahedral and two tetrahedral magnetic sublattices is discussed. A local environment computation on the octahedral sites confirms the assumption that the wide distribution found for the 4.2 K octahedral hyperfine fields is due to the random occupation by Fe³⁺ and Ge⁴⁺ ions of the nearest cation environment of the octahedral iron. The effect of substituting Ln rare earth ions in the Thompson cubes on the magnetic behaviour of these compounds is pointed out.     

The supersymmetric transfer matrix for linear chains with nondiagonal disorder

A study is made of the supersymmetric transfer matrix of then-orbital linear chain with Gaussian nondiagonal and diagonal disorder in the matrix (Hubbard-Stratonovich) variables. This formalism is applied to the one-point Green's function. Invariant functions of supersymmetric matrices are discussed in Section 3.Work supported by the Deutsche Forschungsgemeinschaft.     

On the concept of code-isomorphy

LetF be a finite set of cardinality ¦F¦ =q 2,n 1 an integer and :F ⁿ×Fⁿ₀ theHamming metric. Acode isomorphism C D between two block codesC,D Fⁿ is defined as an isometry which can be extended to an isometry of the whole space Fⁿ. Any permutation S _n of the positions canonically induces a so-calledequivalence map Aut Fⁿ; any system (₁,₂,...,_n) ofn permutations of the character setF induces a so-calledconfiguration Aat Fⁿ. The group Aut Fⁿ of all isometries of Fⁿ turns out to be semidirect product of the configuration group with the symmetric group of degreen. The codeword estimating failure probability of a maximum likelihood codeword estimator for aq-nary symmetric channel does not depend on the transmitted codeword, if the automorphism group of the code acts transitively on the set of codewords. When using a systematic (n, k)-encoder, the symbol decoding failure probability does not depend on the transmitted symbol or on the time of transmission if the configuration group and the automorphism group act transitively on the set of codewords resp. on the set of thek information positions.In memoriam Giuseppe Tallini     

From the Hamiltonian to the Lagrangean formalism for 1-reducible theories. The Freedman-Townsend model

The paper presents a possible path to the sp(3) BRST Lagrangean formalism for a 1-reducible gauge field theory starting from the Hamiltonian one. This appears to be not at all a trivial attempt and will allow explanation of the structure of generators and the form of the master equations in the Lagrangean sp(3) theories. The Freedman-Townsend model, for which a Lagrangean (covariant) sp(3) theory is important, is presented.