Mass Spectrometric Study on the Combustion of Tetramethylsilane and the Formation of Silicon Oxide Clusters in Premixed Laminar Low-Pressure Synthesis Flames.

This work investigates the decomposition of tetramethylsilane and the formation of silicon oxide clusters in a laminar premixed low-pressure hydrogen flame using molecular-beam mass spectrometry (MBMS). A comprehensive list of the species that exist in the gas phase was compiled and spatially resolved mole fraction profiles of species in the flame were obtained. Quantitative data in dependence of height above the burner were obtained for all major species and intermediates. The MBMS detection technique allowed to monitor Si-C-O-H, and Si-O-H-containing compounds as well as C1-C2 species. The measured data show that the reaction of tetramethylsilane is initiated by H-abstraction from a methyl group and subsequent formation of oxygenated species. The measurements suggest that combustion of tetramethylsilane in a hydrogen flame proceeds mainly by a stepwise substitution of the methyl ligands by hydroxyl groups. Molecular and radical intermediates like Si(CH3)2OH, Si(OH)3, and Si(OH)4 are formed in the reaction zone. Significant amounts of Si(OH)4 are present at large distances above the burner. A repetitive growth pattern suggests that the monomer Si(OH)4 is a likely species initiating the formation and growth of larger silicon oxide clusters, e.g., Si4O10H4, Si5O12H4, and Si6O14H4, that can form nanoparticles in subsequent reactions.

Relationships of 18F-FDG uptake by primary tumors with prognostic factors and molecular subtype in ductal breast cancer.

OBJECTIVES: In this study, we aimed to investigate the correlation between SUVmax of primary tumor and prognostic factors/molecular subtype in ductal breast cancer patients. MATERIALS AND METHODS: We retrospectively reviewed 150 female patients with pathologically proven invasive ductal breast cancer from January 2015 to October 2019 who underwent 18F-FDG PET/CT for initial staging. Histopathological prognostic features of the primary tumor (histological grade, hormone receptor status, Ki-67 index, vb.) were obtained from the tru-cut biopsy report. In 18F-FDG PET/CT studies, the maximum standardized uptake value (SUVmax) of the primary breast tumor was calculated and compared with the presence of axillary lymphadenopathy and/or distant metastases, histopathological prognostic factors and molecular subtype. RESULTS: The high SUVmax of primary breast tumors is significantly correlated with the clinicopathological factors: high tumor size, high histologic grade, high Ki-67 index, axillary lymph node positivity and distant metastasis. SUVmax value was significantly higher in patients with basal subtype than patients with Luminal A subtype (8.14±3.71 and 4.64±2.45, p=0.002). Correlation analysis revealed a low correlation between Ki-67 index and SUVmax (r=0.276, p=0.001) and moderate correlation between tumor size and SUVmax (r=0.470, p=0.001). In multivariate linear regression analysis, Ki-67 index and tumor size had a statistically significant effect on SUVmax values. As these parameters increase, it is seen that it increases SUVmax values (p=0.004, Std Beta: 0.228, 95% CI: 0.010-0.055 and p=0.001, Std Beta: 0.374, 95% CI: 0.55-0.136, respectively). CONCLUSION: High SUVmax value is associated with prognotic factors suggesting poor prognosis. Pretreatment 18F-FDG PET/CT can be used as a tool to predict prognosis in breast cancer.

Study for online range monitoring with the interaction vertex imaging method.

Ion beam therapy enables a highly accurate dose conformation delivery to the tumor due to the finite range of charged ions in matter (i.e. Bragg peak (BP)). Consequently, the dose profile is very sensitive to patients anatomical changes as well as minor mispositioning, and so it requires improved dose control techniques. Proton interaction vertex imaging (IVI) could offer an online range control in carbon ion therapy. In this paper, a statistical method was used to study the sensitivity of the IVI technique on experimental data obtained from the Heidelberg Ion-Beam Therapy Center. The vertices of secondary protons were reconstructed with pixelized silicon detectors. The statistical study used the [Formula: see text] test of the reconstructed vertex distributions for a given displacement of the BP position as a function of the impinging carbon ions. Different phantom configurations were used with or without bone equivalent tissue and air inserts. The inflection points in the fall-off region of the longitudinal vertex distribution were computed using different methods, while the relation with the BP position was established. In the present setup, the resolution of the BP position was about 4-5 mm in the homogeneous phantom under clinical conditions (106 incident carbon ions). Our results show that the IVI method could therefore monitor the BP position with a promising resolution in clinical conditions.

The role of Hofbauer cells on the pathogenesis of early pregnancy loss.

INTRODUCTION: Hofbauer cells (HC) are the placental macrophages that play a significant role in many important placental events. The aim of this retrospective study is to investigate the role of HC in the pathogenesis of early pregnancy loss (EPL). METHODS: The slides were obtained from archival blocks of missed abortion (MA, n = 15) and blighted ovum (BO, n = 15) cases. Unwanted pregnancies materials constituted the control group (n = 15). HC and endothelial cells were identified using immunohistochemical methods. HC were counted under light microscope. The extent of villous vasculature was evaluated using two methods; the Chalkey method and microvessel scoring. RESULTS: The mean number of villous HC was found to be significantly higher in both MA and BO groups in contrast to the control group. MA group also showed a higher number of HC in comparison with the BO group. Higher microvessel scoring was also found in MA group in contrast to other two groups. Chalkey method revealed no significant difference in the extent of villous vasculature for the control group in comparison with MA and BO. DISCUSSION: As we identified relatively low quantity of HC in BO associated with defective vasculature, we hypothesize that an inadequate microvessel formation after hypoxic insult can explain the pathogenesis of BO. We believe that HC are increased in MA due to their divergent roles on immunity and inflammation. CONCLUSION: We therefore conclude that HC may be of biological importance in the pathogenesis of EPL.