Gold dithiocarbamate derivatives as potential antineoplastic agents: design, spectroscopic properties, and in vitro antitumor activity

At present, cisplatin (cis-diamminodichloroplatinum(II)) is one of the most largely employed anticancer drugs as it is effective in the treatment of 70-90% of testicular and, in combination with other drugs, of ovarian, small cell lung, bladder, brain, and breast tumors. Anyway, despite its high effectiveness, it exhibits some clinical problems related to its use in the curative therapy, such as a severe normal tissue toxicity (in particular, nephrotoxicity) and the frequent occurrence of initial and acquired resistance to the treatment. To obtain compounds with superior chemotherapeutic index in terms of increased bioavailability, higher cytotoxicity, and lower side effects than cisplatin, we report here on some gold(I) and gold(III) complexes with dithiocarbamate ligands (DMDT = N,N-dimethyldithiocarbamate; DMDTM = S-methyl-N,N-dimethyldithiocarbamate; ESDT = ethylsarcosinedithiocarbamate), which have been synthesized, purified, and characterized by means of elemental analyses, conductivity measurements, mono- and bidimensional NMR, FT-IR, and UV-vis spectroscopy, and thermal analyses. Moreover, the electrochemical properties of the designed compounds have been studied through cyclic voltammetry. All the synthesized gold complexes have been tested for their in vitro cytotoxic activity. Remarkably, most of them, in particular gold(III) derivatives of N,N-dimethyldithiocarbamate and ethylsarcosinedithiocarbamate, have been proved to be much more cytotoxic in vitro than cisplatin, with IC50 values about 1- to 4-fold lower than that of the reference drug, even toward human tumor cell lines intrinsically resistant to cisplatin itself. Moreover, they appeared to be much more cytotoxic also on the cisplatin-resistant cell lines, with activity levels comparable to those on the corresponding cisplatin-sensitive cell lines, ruling out the occurrence of cross-resistance phenomena and supporting the hypothesis of a different antitumor activity mechanism of action.     

Plane Sources of Waves in the Presence of Magnetic Field

In this paper the generation of harmonic waves in an elastic magneticmaterial, which is a perfect conductor of electricity, isconsidered. It has been assumed that an infinite body is subjected tothe action of an initially constant magnetic fieldH = (H,0,0) and in the plane ax+by=0 acts a source ofdistortion. It has been shown that this source may produce bothtransverse and longitudinal waves and each of them consists of two parts,which propagate with different speeds. The amplitudes and speeds in dependence on theangle between the direction of wave propagation and the magnetic fieldintensity H have been discussed.     

Power loss mechanisms in small area monolithic-interconnected photovoltaic modules

Power loss mechanisms in small area monolithic-interconnected photovoltaic modules (MIM) are described and evaluated. Optical and electrical losses are quantified and individual loss components are derived for loss mechanisms of small area radial (radius?=?1?mm) pie-shaped six-segment GaAs MIM laser power converter. At low monochromatic homogeneous illumination (G_low?=?1.8?W/cm², λ₀?=?809?nm) conversion efficiency of the cell, designed for a low irradiance, is reduced by 3.7%_abs. due to isolation trench optical losses and by 7.0%_abs. due to electrical losses (mainly perimeter recombination). Electrical losses in a device designed for a high irradiance, result in 18%_abs. decrease of output power under homogeneous monochromatic illumination (G_high?=?83.1?W/cm², λ₀?=?809?nm), while 11.6%_abs. losses are attributed to optical reasons. Regardless the irradiance level, optical losses further increase if the device is illuminated with a Gaussian instead of an ideal flattop beam profile. In this case, beam spillage losses occur and losses due to isolation trenches and reflections from metallization are elevated. On top of that, additional current mismatch losses occur, if individual MIM’s segments are not equally illuminated. For the studied device, a 29?μm off center misalignment of a Gaussian shaped beam (with 1% spillage) reduces the short circuit current I_sc by 10%_abs. due to the current mismatch between segments.     

Transient photoluminescence decay study of minority carrier lifetime in GaAs heteroface solar cell structures

Transient photoluminescence decay has been studied theoretically and experimentally as a technique for the investigation of GaAs solar cell materials and solar cell structures. The time-dependent continuity equation was solved using two variable boundary conditions modelling the interface between the emitter and hetero-window layer (AlGaAs) and between the emitter and space charge region, respectively. The solution was found with help of the Fourier transform method and the method of residues. There results an analytical expression for the time dependent photoluminescence (PL) intensity. The influence of various solar cell parameters on this photoluminescence transient has been studied in detail. An experimental investigation of transient PL decay was performed using a synchronously pumped mode locked and cavity dumped Nd:YAG/dye laser system for excitation and an optical sampling oscilloscope as the detector. GaAs wafers with and without surface passivation have been measured as well as hetero-window pn-structures and processed solar cells. A fit of the theoretical PL transients to the measured transients allows surface and bulk recombination parameters to be determined.Dedicated to H.-J. Queisser on the occasion of his 60th birthday     

The thermal decomposition of platinum(II) and (IV) complexes

The decomposition characteristics of Pt(II) and Pt(IV) complexes in hydrogen, air and argon were investigated by thermal gravimetric and differential thermal analysis. Based on weight-loss measurements, the thermal stability in hydrogen increased in the order: hexachloroplatinic acid<platinum acetyl acetonate<platinum diamino dinitrite<tetrammine platinous hydroxide<tetrammine platinous chloride<platinum phthalocyanine; whereas in air, the order was: hexachloroplatinic acid<tetrammine platinous hydroxide<platinum acetyl acetonate<platinum diamino dinitrite<tetrammine platinous chloride. The platinum complexes were more stable in air than in hydrogen where decomposition was observed in all platinum samples at temperatures below 200°C.     

Calibrated numerical model of a GaInP–GaAs dual‐junction solar cell

In this letter a calibrated numerical model of a III–V dual‐junction solar cell including tunnel diode and Bragg reflector is presented. The quantum efficiencies of the subcells are computed by using the principle of current‐limitation in monolithic multi‐junction solar cells. A special procedure with bias‐illumination and bias‐voltage was implemented. Numerical simulations are used to study the influence of the top cell thickness on the cells' quantum efficiency and on the current‐matching condition. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Kinetics of Degradation of Biapenem

The kinetic and thermodynamic analysis of biapenem degradation was conducted during acid–base hydrolysis, under the influence of buffer components and in the solid state at increased temperature (dry air) and relative air humidity (RH > 50%). The effects of the initial concentration of biapenem and the formation of degradation products on its stability were investigated.     

Development of a process for routine production of123I using the127I(p, 5n)123Xe→123I reaction

The object of this paper is to give details of a production method for¹²³I, now in routine use at Harwell. We employ the (p, 5n) reaction, irradiating a liquid target of di-iodomethane (CH₂I₂) spiked with additional iodine, with 58 MeV protons. A yield of ∼9 mCi/μAh is obtained; the only detectable radionuclidic impurity is¹²⁵I, present to the extent of ∼0.15% by activity at the time of separation of Xe from I.