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Dissociative ionization of Si(CH[SUB3])Cl[SUB3] has been investigated by photoionization mass spectrometry and calculations of molecular electronic structure. From the photoionization efficiency spectra of ions measured over an energy range 9-30 eV, we determined appearance energies of the parentcation and various fragment cations. The ionization energy of Si(CH[SUB3])Cl[SUB3] is 11.18 eV. A fragment SiCl[SUP+,SUB3] appears at 11.77 eV and a second fragment Si(CH[SUB3])Cl[SUP+,SUB2] at 12.02 eV. Molecular electronic SiCl[SUB3] calculations of structures and energies of the (CH[SUB3])Cl[SUP+,SUB3] radical cation and various fragment cations are made with GAUSSIAN-2 and GAUSSIAN-3 in the GAUSSIAN 98 package. Reaction energies for various fragmentation processes are computed, in satisfactory agreement with experimental data for dissociation. Results of these calculations are applied to establish dissociative photoionization channels of Si(CH[SUB3])Cl[SUB3] near the ionization threshold. [ABSTRACT FROM AUTHOR]

Tunable and polarized soft x-ray radiation was used to excite core electrons of H2O. Angle-resolved proton yields were measured by retarding potential analyzers at 0° and 90° with respect to the polarization vector of the radiation. The ability of angle-resolved detection to reveal hidden resonances in rich molecular spectra is demonstrated, and the anisotropy parameter obtained from the two ion yields identifies the symmetries and the relative oscillator strengths of the core-hole excited states in the near-edge region of the spectrum. The analysis of the data substantiates the validity of the axial recoil approximation and provides evidence for ultrafast dissociation. Comparisons with the results of theoretical calculations are made. [ABSTRACT FROM AUTHOR]

The symmetry of excited states reached by photoexcitation of K-shell electrons of N2 and O2 is identified from the fragmentation anisotropy. For each molecule, ion yield excitation spectra were obtained at 90°, 54.7°, and 0° relative to the axis of soft x-ray polarization. The degree of polarization of the synchrotron radiation was determined experimentally. From this determination and the angular dependence of the ion yield, the photoabsorption anisotropy parameter β is obtained as a function of photon energy. Variations in the β spectra are discussed in terms of previously assigned spectral features and are compared with other experimental results. A comparison also is made with theoretical calculations, which are available for the case of N2. [ABSTRACT FROM AUTHOR]

Electron energy spectra characterizing the relaxation of molecular oxygen from different core hole excited states are reported. By using monochromatic synchrotron radiation, spectra are obtained with excitation at the π* and σ* resonances and at various energies above the ionization threshold. The spectra obtained with excitation above threshold are very similar and result from Auger decay. The spectra obtained at the σ* resonance result from spectator autoionization, and those for the π* resonance result from both spectator and participator autoionization. The σ* resonance is broadened by spectral congestion, and the autoionization spectra indicate the presence of three components. Configurations and states produced by the electronic decay are identified, and a correlation between spectator screening and term values is documented. [ABSTRACT FROM AUTHOR]

Presents a study which characterized the native oxide, thermally oxidized and hydrofluoric acid rinsed surfaces of silicon (100) by photon stimulated ion desorption. Experimental details; Results and discussion; Conclusion.

An experimental method is described that is directed at monitoring the creation and decay of core hole states in molecules from state-to-state. Data in the form of a coincidence map are presented and analyzed for the case of nitrous oxide. [ABSTRACT FROM AUTHOR]

Auranofin, an FDA-approved drug for rheumatoid arthritis, has emerged as a promising antiparasitic medication in recent years. The gold(I) ion in auranofin is postulated to be responsible for its antiparasitic activity. Notably , aurothiomalate and aurothioglucose also contain gold(I), and, like auranofin, they were previously used to treat rheumatoid arthritis. Whether they have antiparasitic activity remains to be elucidated. Herein, we demonstrated that auranofin and similar derivatives, but not aurothiomalate and aurothioglucose, inhibited the growth of Toxoplasma gondii in vitro . We found that auranofin affected the T. gondii biological cycle (lytic cycle) by inhibiting T. gondii's invasion and triggering its egress from the host cell. However, auranofin could not prevent parasite replication once T. gondii resided within the host. Auranofin treatment induced apoptosis in T. gondii parasites , as demonstrated by its reduced size and elevated phosphatidylserine externalization (PS). Notably, the gold from auranofin enters the cytoplasm of T. gondii, as demonstrated by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS).IMPORTANCEToxoplasmosis, caused by Toxoplasma gondii , is a devastating disease affecting the brain and the eyes, frequently affecting immunocompromised individuals. Approximately 60 million people in the United States are already infected with T. gondii , representing a population at-risk of developing toxoplasmosis. Recent advances in treating cancer, autoimmune diseases, and organ transplants have contributed to this at-risk population's exponential growth. Paradoxically, treatments for toxoplasmosis have remained the same for more than 60 years, relying on medications well-known for their bone marrow toxicity and allergic reactions. Discovering new therapies is a priority, and repurposing FDA-approved drugs is an alternative approach to speed up drug discovery. Herein, we report the effect of auranofin, an FDA-approved drug, on the biological cycle of T. gondii and how both the phosphine ligand and the gold molecule determine the anti-parasitic activity of auranofin and other gold compounds. Our studies would contribute to the pipeline of candidate anti- T. gondii agents., Competing Interests: The authors declare no conflict of interest.

State-selective fragmentation dynamics for excited fragments and ionic fragments of gaseous and condensed Si(CH3)2Cl2 following Cl 2p and Si 2p core-level excitations have been characterized. The Cl 2p-->15a1* excitation of Si(CH3)2Cl2 induces significant enhancement of the Cl+ desorption yield in the condensed phase and the Si(CH3)+2 and SiCH+3 yields in the gaseous phase. The core-to-Rydberg excitations at both Si 2p and Cl 2p edges lead to enhanced production of the excited fragments. These complementary results provide deeper insight into the origin of state-selective fragmentation of molecules via core-level excitation.

An outbreak of PCB poisoning through consumption of the contaminated rice oil in Central Taiwan was investigated. It covered four counties and there were 1,843 cases by the end of 1980. The highest frequency of incidence occurred during the period from March to July 1979. Severity of clinical manifestations was graded, most patients exhibiting mild or moderate severity. The major age group of the outbreak was between 11 to 20 years old. Most of the victims were students and factory workers. The amount of PCB intake in each victim was estimated to be 0.7 to 1.84 gm and the latent period from the time of intake to the onset of clinical manifestations was approximately three to four months. The patients' blood PCB concentrations ranged from 3 to 1,156 ppb. In 613 patients, 44.37% (272 patients) had PCB levels of 51-100 ppb, and 27.57% (169 patients) had levels over 100 ppb.