Microchannel fabrication in PMMA based on localized heating using high-repetition rate femtosecond pulses

Abstract not reproduced here by request of the publisher. The text is available from: http://dx.doi.org/10.1117/12.638336

Microchannel fabrication in PMMA based on localized heating by nanojoule high repetitions rate femtosecond pulses

Microchannels are fabricated in a poly(methyl methacrylate) substrate by high repetition rate, nanojoule femtosecond laser pulses. The mechanism for channel fabrication is based on the localized heating of the substrate due to the high repetition rate of the laser, resulting in smooth walled cylindrical channels. Microchannels with diameters of 8 – 20 µm can be fabricated at 800 µm/s using 80 fs pulses at a repetition rate of 80 MHz and energy of 0.9 nJ/pulse

Formation of voids in a doped polymethylmethacrylate polymer

We report on the formation of submicrometer voids within a doped polymethylmethacrylate (PMMA) polymer under multiphoton absorption excited by an infrared laser beam. An ultrashort pulsed laser beam of pulse width 80 fs at a repetition rate of 82 MHz and a wavelength of 800 nm is focused into a PMMA-based photorefractive polymer consisting of 2,5-dimethyl-4(p- nitrophenylazo)anisole, 2,4,7-trinitro-9-fluorenone, and N-ethylcarbazole. The large change in refractive index associated with a void allows confocal reflection microscopy to be used as a detection method. Voids can be arranged in a multilayered structure for read-only high-density optical data storage. © 2002 American Institute of Physics

Three-dimensional coherent transfer function for reflection confocal microscopy in the presence of refractive-index mismatch

The three-dimensional (3-D) coherent transfer function for reflection confocal microscopy of high-numerical-aperture objectives is derived and calculated in the presence of refractive-index mismatch when a laser beam is focused into a medium of refractive index different from its immersion medium. This aberrated coherent transfer function is then used to estimate the readout efficiency of 3-D data bits recorded in a thick medium. It is shown that the readout efficiency of confocal microscopy for 3-D bit data storage is decreased with the focal depth of an objective in a recording medium. However, a high readout efficiency can be maintained if the tube length of a reading objective is linearly altered to compensate for the spherical aberration caused by the refractive-index mismatch

2,2,5,5-Tetramethyloxolane (TMO) Replacing Toluene as an Azeotropic Solvent for the Synthesis of Polyester Resins

A diverse array of chemical substances, from small molecules to macromolecules such as polyester resins for coatings applications, are synthesized in large quantities by means of condensation and polycondensation reactions. Condensation reactions starting from acids and alcohols are commonly used in industrial procedures because they utilize inexpensive starting materials and water is produced as the only byproduct. To ensure efficient removal of the water, the reaction can be conducted under reduced pressure or assisted by azeotropic solvents. For the latter, toluene is often used. In this study we were interested in exploring whether 2,2,5,5-tetramethyloxolane (TMO) also known as tetramethyl-tetrahydrofuran can be used as a safer and benign alternative to toluene. Therefore, the azeotropic polycondensation of polyester resins was examined in the presence of toluene or TMO. Furthermore, the nature of the TMO-water azeotrope and the stability of TMO under the reaction conditions were explored and compared to toluene. Results obtained showed that TMO does indeed form an azeotropic mixture and can be used as a safer alternative to toluene to efficiently remove water in polycondensation processes

Additional file 3: Table S2. of Comprehensive analysis of promoter-proximal RNA polymerase II pausing across mammalian cell types

GO biological process enrichment analysis for the top and bottom 25 % of genes by PI for each cell type. (XLSX 23028 kb

Additional file 2: Table S1. of Comprehensive analysis of promoter-proximal RNA polymerase II pausing across mammalian cell types

Datasets used in this study. (XLSX 19 kb

Additional file 4: Table S3. of Comprehensive analysis of promoter-proximal RNA polymerase II pausing across mammalian cell types

List of primers used in this study. (XLSX 10 kb

Additional file 1: Figure S1. of Comprehensive analysis of promoter-proximal RNA polymerase II pausing across mammalian cell types

Measurement of pausing index (PI). Figure S2. Robustness of RNAP2 pausing calculations. Figure S3. Pausing across cell and tissue types. Figure S4. Correlation between pausing and promoter GC and CpG content Figure S5. Relationship between whole gene, TSSR, and gene body RNAP2 density and PI to gene expression for GM12878, H1, K562, IMR90, HUVEC, and HepG2 cells. Figure S6. Grouping paused and non-paused genes by mean population-wide expression shows no consistent expression level difference within quantile. Figure S7. Effect of extracellular stimuli on RNAP2 pausing. Figure S8. Relationship of gene expression to TSSR and gene body RNAP2 density and to PI. Figure S9. The inflection point does not appear to be driven by a limit to the level of initiating RNAP2. Figure S10. Nucleosome positioning and RNAP2 pausing. Figure S11. Chromatin features and RNAP2 pausing. (PDF 7287 kb