Cell‐Selective,Apoptosis‐inducing Rhodium(III) Crown Thiaether Complexes

Half‐sandwich rhodium(III) polypyridyl (pp) complexes with the metal atom capped by the facial crown thiaether 1,4,7‐trithiacyclononane [9]aneS₃ represent a promising class of apoptosis‐inducing potent cytostatic agents. The necrotic damage caused by the complexes is negligible. In vitro cytotoxicity assays with the human cancer cell lines MCF‐7 and HT‐29 and immortalized HEK‐293 cells indicate that the dicationic κ²N(imino) complexes [([9]aneS₃)RhCl(pp)]²⁺ are much more active than monocationic complexes [([9]aneS₃)RhCl₂(L)]⁺ (L=imidazole, CH₃CN). Whereas the κ²N(amino) complex [([9]aneS₃)RhCl(piperazine)]²⁺ is inactive, replacing piperazine with the structurally analogous κ²S (thiaether) ligand 1,4‐dithiane restores cytotoxicity as evidenced by IC₅₀ values in the range 8.1‐11.6 μM . Spectroscopic (CD, UV/Vis, NOESY) and viscosity measurements indicate that the active dppz complex 8 (IC₅₀ values: 4.7–8.9 μM ) exhibits strong intercalative binding towards DNA whereas the even more potent bipyrimidine complex 9 (IC₅₀ values: 0.6–1.9 μM ) causes no alteration of the duplex B conformation. Weaker intercalative binding is observed for the dpq complex 7 . A comparative annexin V–propidium iodide binding assay with lymphoma (BJAB) cells and healthy leukocytes demonstrates that the cytotoxic activity of complex 8 and particularly complex 9 is highly selective towards the malignant cells.     

An investigation of phase transformation behavior in sputter-deposited PtMn thin films

Sputter-deposited, equiatomic PtMn thin films have application in giant magnetoresistive spin valves, tunneling magnetoresistive spin valves, and magnetic random access memory. However, the as-deposited films are found to be a disordered A1 phase in a paramagnetic state rather than an antiferromagnetic phase with L1₀ structure, which is needed for device operation. Therefore, a postannealing step is required to induce the phase transformation from the asdeposited A1 face-centered-cubic phase to the antiferromagnetic L1₀ phase. The A1 to L1₀ metastable transformation was studied by x-ray diffraction and differential-scanning calorimetry. An exothermic transformation enthalpy of −12.1 kJ/mol of atoms was determined. The transformation kinetics were simulated using the Johnson-Mehl-Avrami analysis.     

New insights on the consolidation of salt weathered limestone: the case study of Modica stone

Bulletin of Engineering Geology and the Environment - The deterioration of a stone material is related to its pore structure, which affects the interaction between surface and environmental agents....     

The behaviour of consolidated Neapolitan yellow Tuff against salt weathering

Bulletin of Engineering Geology and the Environment - Salt crystallization is a strong weathering agent in porous building materials. The crystallization pressure exerted by salt crystals, growing...     

A model approach to assess the long-term trends of indirect photochemistry in lake water. The case of Lake Maggiore (NW Italy)

A model-based approach is here developed and applied to predict the long-term trends of indirect photochemical processes in the surface layer (5 m water depth) of Lake Maggiore, NW Italy. For this lake, time series of the main parameters of photochemical importance that cover almost two decades are available. As a way to assess the relevant photochemical reactions, the modelled steady-state concentrations of important photogenerated transients (^•OH, ³CDOM* and CO₃^-•) were taken into account. A multivariate analysis approach was adopted to have an overview of the system, to emphasise relationships among chemical, photochemical and seasonal variables, and to highlight annual and long-term trends. Over the considered time period, because of the decrease of the dissolved organic carbon (DOC) content of water and of the increase of alkalinity, a significant increase is predicted for the steady-state concentrations of the radicals ^•OH and CO₃^−•. Therefore, the photochemical degradation processes that involve the two radical species would be enhanced. Another issue of potential photochemical importance is related to the winter maxima of nitrate (a photochemical ^•OH source) and the summer maxima of DOC (^•OH sink and ³CDOM* source) in the lake water under consideration. From the combination of sunlight irradiance and chemical composition data, one predicts that the processes involving ^•OH and CO₃^−• would be most important in spring, while the reactions involving ³CDOM* would be most important in summer.     

Identification of large polycyclic aromatic hydrocarbons in carbon particulates formed in a fuel-rich premixed ethylene flame

Large polycyclic aromatic hydrocarbons were identified in carbon particulate sampled in a fuel-rich premixed ethylene flame. The particulate was extracted with dichloromethane (DCM) in order to separate the soluble organic species (DCM-extract) from the solid carbon (soot). After DCM extraction soot was re-extracted with N-methyl pyrrolidone (NMP) obtaining the NMP-extract. Both the DCM-extract and NMP-extract were further fractionated by size exclusion chromatography in selected molecular weight (MW) ranges. Large polycyclic aromatic hydrocarbons obtained by regular incorporation of C₂ and/or C₂H₂ unit (24/26 rule) occurring in both odd and even series of carbon atom number of polycyclic aromatic hydrocarbons, were identified by laser desorption ionization–mass spectrometry (LDI–MS) analysis of the lighter MW fractions of both the DCM-extract and NMP-extract (100–400 u MW of the DCM-extract and 200–600 u fractions of the NMP-extract). The LDI–MS spectra of the heaviest MW fractions of DCM-extract and NMP-extract (600–2000 u and 600–5000 u fraction) showed a continuous spectrum of masses typical of polymeric structures. The UV–visible absorption and emission spectral analysis corroborated the assignment of lighter and of heavier fractions of DCM-extract and NMP-extract to PAH and to polymeric aromatic structures, respectively.     

Advanced distillation curve measurements for corrosive fluids: Application to two crude oils

We have recently introduced several important improvements in the measurement of distillation curves for complex fluids. The modifications include a composition-explicit data channel for each distillate fraction (for both qualitative and quantitative analysis) and corrosivity assessment of each distillate fraction. The composition-explicit information is achieved with a new sampling approach that allows precise qualitative as well as quantitative analyses of each fraction, on the fly. We have applied the new method to a variety of fluids, including simple n-alkanes, rocket propellant, gasoline, jet fuels, and a hydrocarbon fluid made corrosive with dissolved hydrogen sulfide. In the current contribution, we present the application of the advanced distillation curve method to two samples of crude oil. A primary motivation behind the work is to precisely measure the distillation curves of these oils using our advanced distillation apparatus; these low uncertainty measurements of true thermodynamic state points can be used for equation of state development and differentiation of crude oil samples. Then, the information content of each distillation was extended much further by use of the composition-explicit data channel: gas chromatography–mass spectrometry (GC–MS), infrared spectrophotometry (IR), gas chromatography with sulfur chemiluminescence detection (GC–SCD), and the copper strip corrosion test (CSCT) were used for each distillate volume fraction sampled. Consequently, for each volume fraction of crude oil distillate sampled, we can address the composition, quantitate the total sulfur content, and measure the corrosivity.     

Quantification of NTproBNP in rat serum using immunoprecipitation and LC/MS/MS: a biomarker of drug-induced cardiac hypertrophy

Brain natriuretic peptide (BNP) and N-terminal proBNP (NTproBNP) are well established in the clinic as biomarkers of heart failure. BNP hormone and the inactive NTproBNP are predominantly secreted in the ventricles of the heart in response to pressure overload and, consequently, are being investigated as markers of drug-induced cardiac hypertrophy in rat to support drug development. In the work presented here, an immunoaffinity-based LC/MS/MS assay was developed and validated to measure a selective tryptic fragment of NTproBNP in rat serum. The assay covers the range of 13-329 pg/mL of the tryptic fragment LLELIR, corresponding to 0.1-2.5 ng/mL intact NTproBNP. A stable isotope-labeled version of NTproBNP containing the tryptic fragment LLELI[13C615N1]R was prepared by solid-phase peptide synthesis and was used as an internal standard to minimize assay variability. Due to endogenous NTproBNP present in rat serum, human serum was used as the control matrix, and parallelism between rat and human serum was established by standard addition. Assay accuracy (% RE) and precision (% CV) were measured at three concentrations on each of 4 days and did not exceed 4.2 and 14.5%, respectively. Additionally, study data are presented from the application of this assay in which rats demonstrated a significant increase in NTproBNP serum concentration following administration of an agent known to induce cardiac hypertrophy. In this study, the relationship between serum NTproBNP and cardiac hypertrophy was corroborated by increases in heart weight and magnetic resonance imaging of the test subjects' left ventricle. To our knowledge, this represents the first reported assay for NTproBNP in preclinical species for the assessment of cardiac hypertrophy.