Markéta Urbanová

Laser photolysis of liquid benzene and hexafluorobenzene: Graphitic and polymeric carbon formation at ambient temperature

Abstract ArF laser-induced liquid-phase photolysis of benzene and hexafluorobenzene afford similar products which are polyaromatic hydrocarbons or fluorocarbons with the preponderance of biphenyl or decafluorobiphenyl, graphite, and polymeric H-containing or F-containing carbon. The remarkable feature is that the graphite formation occurs at ambient temperature of the irradiated liquids; photolytic graphitization modes must therefore be different from those occurring in thermally-induced graphitization at temperatures above 2500 °C.

Smooth muscle actin-expressing stromal fibroblasts in head and neck squamous cell carcinoma: Increased expression of galectin-1 and induction of poor prognosis factors

Tumor stroma is an active part influencing the biological properties of malignancies via molecular cross‐talk. Cancer‐associated fibroblasts play a significant role in this interaction. These cells frequently express smooth muscle actin and can be classified as myofibroblasts. The adhesion/growth‐regulatory lectin galectin‐1 is an effector for their generation. In our study, we set the presence of smooth muscle actin‐positive cancer‐associated fibroblasts in relation to this endogenous lectin and an in vivo competitor (galectin‐3). In squamous cell carcinomas of head and neck, upregulation of galectin‐1 presence was highly significantly correlated to presence of smooth muscle actin‐positive cancer‐associated fibroblasts in the tumor (p = 4 × 10−8). To pinpoint further correlations on the molecular level, we applied microarray analyses to the transcription profiles of the corresponding tumors. Significant correlations of several transcripts were detected with the protein level of galectin‐1 in the cancer‐associated fibroblasts. These activated genes (MAP3K2, TRIM23, PTPLAD1, FUSIP1, SLC25A40 and SPIN1) are related to known squamous‐cell‐carcinoma poor‐prognosis factors, NF‐κB upregulation and splicing downregulation. These results provide new insights into the significance of presence of myofibroblasts in squamous cell carcinoma.

Si/C phases from the IR laser-induced decomposition of silacyclobutane and 1,3-disilacyclobutane

CO 2 laser-induced infrared multiphoton decomposition (IRMPD) and SF 6 photosensitized decomposition (LPD) of silacyclobutane (SCB) and 1,3-disilacyclobutane (DSCB) in the gas phase results in the very efficient deposition of Si/C/H and SiC materials, and it is inferred that the process is dominated by formation of transient silene ; silene rearrangement to methylsilylene ; silene and methylsilylene dehydrogenation ; and polymerization of SiCH n (n < 4) species. The deposits are sensitive to oxygen. Decomposition and SiC formation are favoured with IRMPD experiments conducted with high-energy fluxes. The laser technique is promising for low-temperature chemical vapour deposition of amorphous SiC.

IR laser-induced decomposition of disiloxane for chemical vapour deposition of poly(hydridosiloxane) films

Continuous-wave CO2-laser-induced gas-phase decomposition of H3SiOSiH3, dominated by elimination and polymerization of transient silanone H2SiO and yielding silane and hydrogen as side-products, represents a convenient process for chemical vapour deposition of poly(hydridosiloxane) films. Copyright

Laser-powered homogeneous pyrolysis of 4-silaspiro[3,3]heptane. A source for 2-silaallene and its polymer

Abstract Continuous-wave CO 2 laser-photosensitized (SF 6 ) decomposition of 4-silaspiro[3,3]heptane is dominated by the transient formation and polymerization of 2-silaallene. The first experimental evidence for 2-silaallene has been achieved via scavenging with alcohols ROH (R  CH 3 , CF 3 CH 2 ) to afford dialkoxy(dimethyl)silanes, (RO) 2 Si(CH 3 ) 2 . ESCA analysis of the polymer demonstrates SiC 2 stoichiometry and indicates the incorporation of oxygen, which may be explained by reaction of the residual Si  C bonds with air.

IR laser-induced decomposition of 1,3–dimethyldisiloxane for chemical vapour deposition of nano-structured methyl(hydrido)silicone phases

The infrared multiphoton decomposition of 1,3-dimethyldisiloxane induced by a TEA CO2 laser yields gaseous C1–C2 hydrocarbons, methylsilane, dimethylsilane, methyldisiloxane and trimethyldisiloxane. These products provide evidence for a range of decomposition steps; amongst these, cleavage of the Si–O bond is important. The process affords chemical vapour deposition of a white solid nano-structured methyl(hydrido)silicone phase that has been characterized by infrared and photoelectron spectroscopy and electron microscopy.

Laser induced chemical vapour deposition of polypyridine films

Continuous-wave CO2 laser photosensitized (SF6) decomposition of pyridine is dominated by dehydrogenative coupling of the heterocyclic rings, and it represents a convenient process for chemical vapour deposition of thin polypyridine films.

IR laser-induced thermolysis and UV laser-induced photolysis of 1,3-diethyldisiloxane: chemical vapour deposition of nanotextured hydridoalkylsilicones

IR laser thermolysis and UV laser photolysis of gaseous 1,3-diethyldisiloxane proceed via different mechanisms: the former involves 1,1-H2 and ethene elimination, whereas the latter is dominated by 1,1-H2 and ethane elimination. The difference plays an important role in determining the composition of the solid nanotextured films deposited from the gas phase.

Formation of hydrogenated Si2O films by UV laser photolysis of disiloxane

ArF laser-induced photolysis of disiloxane in the gas phase results in the cleavage of the Si–H bonds and affords chemical vapour deposition of novel hydrogenated silicon suboxide films. The films are sensitive to ambient atmosphere and were characterised by FTIR and XP spectroscopy and by SEM.

IR laser photosensitized decomposition of trimethyl(2-propynyloxy)silane for chemical vapour deposition of polydimethylsiloxane phases

Abstract The infrared laser-photosensitized (SF 6 ) decomposition of trimethyl(2-propynyloxy)silane (TMPSi) induced by TEA CO 2 laser affords a multitude of unsaturated hydrocarbons and a solid polydimethylsiloxane phase. This process of chemical vapour deposition in which all the silicon of the parent is completely utilised in the formation of the solid phase is briefly compared with UV laser photolysis of TMPSi.