Distinguishing Activities in the Photodynamic Arsenals of the Pigmented Ciliates Blepharisma sinuosum Sawaya, 1940 and Blepharisma japonicum Suzuki, 1954 (Ciliophora: Heterotrichea)

Blepharismins are photodynamic hypericin-like dianthrones produced as a variable pigment blend in Blepharisma ciliates and mostly studied in the Afro-Asiatic Blepharisma japonicum. The present work describes the bioactivity of pigments from the Brazilian Blepharisma sinuosum. Comparative analyses showed that the pigments from both species can trigger photo-induced modifications in phospholipids, but different redox properties and biological activities were assigned for each pigment blend. Stronger activities were detected for B. sinuosum pigments, with the lethal concentration LC₅₀ 10 × lower than B. japonicum pigments in light-irradiated tests against Bacillus cereus and less than half for treatments on the human HeLa tumor cells. HPLC showed B. sinuosum producing a simpler pigment blend, mostly with the blepharismin-C (~ 70%) and blepharismin-E (~ 30%) types. Each blepharismin engaged a specific dose–response profile on sensitive cells. The blepharismin-B and blepharismin-C were the most toxic pigments, showing LC₅₀ ~ 2.5–3.0 µm and ~ 100 µm on B. cereus and HeLa cells, respectively, after illumination. Similarity clustering analysis compiling the bioactivity data revealed two groups of blepharismins: the most active, B and C, and the less active, A, D and E. The B. sinuosum pigment blend includes one representative of each clade. Functional and medical implications are discussed.     

Studies in heavy ion activation analysis I. on the selection of activation reactions

Among the numerous heavy ion reactions, those of potential interest for chemical analysis can be identified based on their Q values, Coulomb barriers, and threshold energies. A simple computer code has been written for these calculations. The use of the calculated data is illustrated with a survey of the possibilities of HIAA with N⁺, Li⁺, B⁺, Be⁺ and C⁺ beams yielding radioisotopes with half-lives of 10 to 10⁴ sec.     

Trace determination of rhodium using proton activation followed by X-ray counting

The reaction¹⁰³Rh(p, n)¹⁰³Pd was investigated for the trace detection of Rh. Maximum activation of Rh with minimal interferences was achieved with protons of 11 MeV. The detection limit for the nondestructive assay of Rh is 0.03 ppm.     

Nanodomain analysis with cluster‐SIMS: application to the characterization of macromolecular brush architecture

We present the application of cluster‐SIMS for the analysis of the nanoscopic surface of diblock brush terpolymers (DBTs). This novel SIMS technique differs from conventional SIMS. It uses Au₄₀₀⁴⁺ projectiles at 520 keV and an event‐by‐event bombardment/detection regime for the analysis of co‐localized molecular species. The performance of this SIMS method was tested on ‘bottle brush’ block molecules featuring a vertical aligned backbone structure. We were able to assess the extent of secondary ion emissions from the surface and analyze the degree of ordered alignment for DBTs by the fluorocarbon surface coverage. We demonstrate the feasibility of characterizing the homogeneity of macromolecular films at the nanoscale. Copyright © 2015 John Wiley & Sons, Ltd.     

Structural characterization of organic molecules by negative ions in laser microprobe mass spectrometry. Part 1—Neutral compounds

Laser microprobe mass spectrometry (LMMS) has been used to systematically study polyfunctional molecules, covering a wide range of structure and polarity. The knowledge about the mechanisms actually involved for desorption and ionization (DI) of organics by laser microbeam irradiation of solid samples at high-power density is rather limited. Therefore we have elaborated a set of tentative hypotheses about DI in LMMS, permitting consistent rationalization of detected signals. The technique apparently combines desorption under mild conditions, shown by the release of intact thermolabiles, with extensive fragmentation. Structural data are typically distributed between cations and anions. Interpretation of negative-ion detection mode mass spectra often represents intricate problems, partly due to the lack of sustaining background information from conventional mass spectrometry. Selected examples are presented to illustrate the occurrence of electron capture ionization, the role of heteroatoms in the formation of negative ions and the tendency to undergo complex skeletal rearrangements. Although LMMS was originally aimed at microprobe applications, it has been found to be a valuable tool in organic mass spectrometry.     

Photon, Electron and Secondary Ion Emission from Single C(60) keV Impacts

This paper presents the first observation of coincidental emission of photons, electrons and secondary ions from individual C(60) keV impacts. An increase in photon, electron and secondary ion yields is observed as a function of C(60) projectile energy. The effect of target structure/composition on photon and electron emissions at the nanometer level is shown for a CsI target. The time-resolved photon emission may be characterized by a fast component emission in the UV-Vis range with a short decay time, while the electron and secondary ion emission follow a Poisson distribution.     

Synthesis,Modification, and Biological Evaluation of a Library of Novel Water-Soluble Thiopyridone-Based Organometallic Complexes and Their Unexpected (Biological) Behavior

A series of 16 dinuclear thiopyridone-based organometallics with excellent water solubility, increased stability and remarkable cytotoxicity were synthesized and characterized. The complexes of this work formed dimeric species featuring a double positive charge in polar protic solvents, accounting for their outstanding solubility in aqueous solution. Most of them displayed higher antiproliferative activity than their parental thiomaltol complex, with unexpected cytotoxicity trends depending on the employed metal center, ligand modification, and cell line. Insights into their behavior in biological systems were gathered by means of amino-acid interaction studies, cytotoxicity tests in 3D spheroid models, laser ablation, cellular accumulation measurements, as well as cell cycle experiments.     

Cis-trihetero-tris-σ-homobenzenes as tridentate ligands - X-ray crystal. Structure analyses of the Co(C6H9N3)2(NO3)3 and Ba(C6H6O3)4(ClO4)2-complexes

According to X-ray crystal structure analyses “cis-benzenetrisimine” ($\text{2}$) and “cis-benzenetrioxide” ($\text{1}$) act as tridentate ligands in their 2:1- and 4:1-complexes $\text{7}$ (Co(C₆H₉N₃)₂(NO₃)₃) and $\text{8}$ (Ba(C₆H₆O₃)₄(ClO₄)₂), resp. The latter is the rare example of an organic complex with the (approximate) T-symmetry.