Modular Synthetic Approach to Carboranyl‒Biomolecules Conjugates

The development of novel, tumor-selective and boron-rich compounds as potential agents for use in boron neutron capture therapy (BNCT) represents a very important field in cancer treatment by radiation therapy. Here, we report the design and synthesis of two promising compounds that combine meta-carborane, a water-soluble monosaccharide and a linking unit, namely glycine or ethylenediamine, for facile coupling with various tumor-selective biomolecules bearing a free amino or carboxylic acid group. In this work, coupling experiments with two selected biomolecules, a coumarin derivative and folic acid, were included. The task of every component in this approach was carefully chosen: the carborane moiety supplies ten boron atoms, which is a tenfold increase in boron content compared to the l-boronophenylalanine (l-BPA) presently used in BNCT; the sugar moiety compensates for the hydrophobic character of the carborane; the linking unit, depending on the chosen biomolecule, acts as the connection between the tumor-selective component and the boron-rich moiety; and the respective tumor-selective biomolecule provides the necessary selectivity. This approach makes it possible to develop a modular and feasible strategy for the synthesis of readily obtainable boron-rich agents with optimized properties for potential applications in BNCT.     

Pressure effects on the quadrupole coupling constant of 7Li in first stage lithium graphite

The pressure dependence of the experimental ⁷Li NMR spectra is reported for first stage lithium graphite (LiC₆) intercalation compound at temperatures T = 232 and 293 K. This experiment together with the presented point charge model calculation of the ⁷Li quadrupole coupling constant $\text{(}\text{e}{}^2\text{qQ}\text{h}\text{)}$ allows an unambiguous determination of the sign of e²qQ/h which is negative: $\text{e}{}^2\text{qQ}\text{h=-52 kHz}$ at p = 1 bar and T = 232 K. The averaged location of the electrons transferred from the Li intercalant to the graphite layers, as estimated in this study, is in excellent agreement with earlier theoretical energy-band calculations. The compressibility of LiC₆ in the c-direction is predicted to be k_c = 1.7 × 10^-12cm²dyn^-1, it agrees with estimates derived from the available phonon dispersion relations.     

Artinian level modules and cancellable sequences

In order to use dualization to study Hilbert functions of artinian level algebras we extend the notion of level sequences and cancellable sequences, introduced by Geramita and Lorenzini, to include Hilbert functions of certain artinian modules. As in the case of algebras a level sequence is cancellable, but now by dualization its reverse is also cancellable which gives a new condition on level sequences. We also give a characterization of the cancellable sequences involving Macaulay representations.     

Five-step phase-shifting algorithms with unknown values of phase shift

The presented work offers new algorithms for phase evaluation in interferometric measurements. Several phase-shifting algorithms with an arbitrary but constant phase-shift between captured intensity frames are proposed. These phase calculation algorithms need to measure five frames of the intensity of the interference field. The algorithms are similarly derived as so called Carré algorithm. The phase evaluation process then does not depend on the linear phase shift errors. Furthermore, the detailed analysis of the algorithms with respect to most important factors, which affect interferometric measurements, is carried out. It is also studied the dependency of the evaluation algorithms on the phase shift values, and the proposed phase calculation algorithms are compared with respect to the resulting phase errors. The influence of most important factors in the measurement and evaluation process was simulated as systematic and random errors using a proposed mathematical model.     

Comparison between Eulerian and Lagrangian semi-analytical models to simulate the pollutant dispersion in the PBL

In this work we display a numerical comparison, under statistical and computational point of view, between semi-analytical Eulerian and Lagrangian dispersion models to simulate the ground-level concentration values of a passive pollutant released from a low height source. The Eulerian approach is based on the solution of the advection–diffusion equation by the Laplace transform technique. The Lagrangian approach is based on solution of the Langevin equation through the Picard’s Iterative Method. Turbulence inputs are calculated according to a parameterization capable of generating continuous values in all stability conditions and in all heights of the Planetary Boundary Layer (PBL). Numerical simulations and comparisons show a good agreement between predicted and observed concentrations values. The comparison reveals the main advantages and disadvantages between the models.     

Bis(phosphino)borates: a new family of monoanionic chelating phosphine ligands

The reaction of dimethyldiaryltin reagents Me(2)SnR(2) (R = Ph (1), p-MePh (2), m,m-Me(2)Ph (3), p-(t)BuPh (4), p-MeOPh (5), p-CF(3)Ph (6)) with BCl(3) provided a high-yielding, simple preparative route to the corresponding diarylchloroboranes R(2)BCl (R = Ph (10), p-MePh (11), m,m-Me(2)Ph (12), p-(t)BuPh (13), p-MeOPh (14), p-CF(3)Ph (15)). In some cases, the desired diarylchloroborane was not formed from an appropriate tin reagent Me(2)SnR(2) (R = o-MeOPh (7), o,o-(MeO)(2)Ph (8), o-CF(3)Ph (9)). The reaction of lithiated methyldiaryl- or methyldialkylphosphines with diarylchloroboranes or dialkylchloroboranes is discussed. Specifically, several new monoanionic bis(phosphino)borates are detailed: [Ph(2)B(CH(2)PPh(2))(2)] (25); [(p-MePh)(2)B(CH(2)PPh(2))(2)] (26); [(p-(t)BuPh)(2)B(CH(2)PPh(2))(2)] (27); [(p-MeOPh)(2)B(CH(2)PPh(2))(2)] (28); [(p-CF(3)Ph)(2)B(CH(2)PPh(2))(2)] (29); [Cy(2)B(CH(2)PPh(2))(2)] (30); [Ph(2)B(CH(2)P[p-(t)BuPh](2))(2)] (31); [(p-MeOPh)(2)B(CH(2)P[p-(t)BuPh](2))(2)] (32); [Ph(2)B(CH(2)P[p-CF(3)Ph](2))(2)] (33); [Ph(2)B(CH(2)P(BH(3))(Me)(2))(2)] (34); [Ph(2)B(CH(2)P(S)(Me)(2))(2)] (35); [Ph(2)B(CH(2)P(i)Pr(2))(2)] (36); [Ph(2)B(CH(2)P(t)Bu(2))(2)] (37); [(m,m-Me(2)Ph)(2)B(CH(2)P(t)Bu(2))(2)] (38). The chelation of diarylphosphine derivatives 25-33 and 36 to platinum was examined by generation of a series of platinum dimethyl complexes. The electronic effects of substituted bis(phosphino)borates on the carbonyl stretching frequency of neutral platinum alkyl carbonyl complexes were studied by infrared spectroscopy. Substituents remote from the metal center (i.e. on boron) have minimal effect on the electronic nature of the metal center, whereas substitution close to the metal center (on phosphorus) has a greater effect on the electronic nature of the metal center.     

Determination of uranium by thermal and epithermal neutron activation in natural waters and in human urine

Uranium is determined via its ²³⁹U nuclide (74.0 keV, t_{$\text{1}\text{2}$} = 23.5 min) in natural waters down to 0.03 ng U ml^-1 after preconcentration with activated carbon and oxine; 30-min irradiation and counting times are used. No preconcentration is required for samples containing more than 4 ng U ml^-1 with 10-min irradiation and counting times. Uranium in urine can be determined under a boron shield at the 5 ng ml^-1 level after 30-min irradiation and counting.     

Thermodynamic Properties and Melting Behavior of Bi–Sn–Zn Alloys

Summary. The partial and integral enthalpies of mixing of liquid Bi–Sn–Zn alloys were determined at 500°C by a drop calorimetric technique using a Calvet-type microcalorimeter. The ternary interaction parameters in the Bi–Sn–Zn system were fitted using the Redlich-Kister-Muggianu model for substitutional solutions, and isoenthalpy curves of the integral molar enthalpy of mixing at 500°C were constructed. Furthermore, a DSC technique was used to determine the liquidus temperatures in three sections (3, 5, and 7 at.% Zn) as well as the invariant reaction temperature of the ternary eutectic L ⇄ (Bi) + (Sn) + (Zn). The ternary eutectic reaction was found at 135°C.