Quantitating Fluorescence Intensity From Fluorophores: Practical Use of MESF Values

The present work uses fluorescein as the model fluorophore and points out critical steps in the use of MESF (Molecules of Equivalent Soluble Fluorophores) values for quantitative flow cytometric measurements. It has been found that emission spectrum matching between a reference solution and an analyte and normalization by the corresponding extinction coefficient are required for quantifying fluorescence signals using flow cytometers. Because of the use of fluorescein, the pH value of the medium is also critical for accurate MESF assignments. Given that the emission spectrum shapes of microbead suspensions and stained biological cells are not significantly different, the percentage of error due to spectrum mismatch is estimated. We have also found that the emission spectrum of a microbead with a seven-methylene linker between the fluorescein and the bead surface (bead7) provides the best match with the spectra from biological cells. Therefore, bead7 is potentially a better calibration standard for flow cytometers than the existing one that is commercially available and used in the present study.     

Experimental study of microwave transmission in snowpack

Microwave transmission loss in a natural snowpack was measured to provide fundamental data for snow subsurface radar. The snowpack consisted of many horizontal stratified layers of relatively large density and water inclusion. Field strength measurements were carried out in the vertical direction across horizontal snow layers in the frequency range 0.6-7.0 GHz. The transmission loss and the extinction coefficients were obtained as a function of frequency     

Plasma Oxidation of a Titanium Electrode in dc-Plasma Above the Water Surface

Plasma oxidation of a titanium electrode above liquid water was investigated to reveal the interaction between metallic titanium and plasma above liquid water. Dc-plasma was generated between the titanium and water electrodes. When the titanium electrode was set as anodal, a thick rutile layer was formed on the surface. We had reported previously that the layer showed the preferred orientation along 〈110〉normal to the surface. The degree of the preferred orientation showed a maximum of 0.8 at the electrode temperature of 1073 K. When the titanium electrode was set as cathodal, a plume was generated with the temperature rise because of the bombarding effect of cationic species in the plasma. The collected particles were spherical and were identified as anatase with a small amount of rutile. Optical emission spectroscopy suggested that an oxide layer (TiO₂) firstly formed on the Ti cathode surface, and then vaporization took place with the temperature rise. The spherical anatase particles were formed from the TiO₂ vapor through the rapid cooling.     

Psychological maladjustment among Asian and White American college students: Controlling for confounds.

Differences in psychological maladjustment among foreign-born Asian-, U.S.-born Asian- and White-American college students were examined, after controlling for variables that have been confounded with ethnicity (i.e., demographics, response set, and personality style) in previous studies. Psychological maladjustment was measured in terms of both intrapersonal and interpersonal distress. Results indicated that foreign-born Asian-American students differed from White-American students on levels of social desirability, other-directedness, and extraversion. However, even after controlling for differences on these variables, greater levels of intrapersonal and interpersonal distress were found for foreign-born Asian-American students. The findings suggest (1) that for Asian-Americans there are ethnic differences in psychological maladjustment that covary with generation level, and (2) that these differences cannot be solely attributed to cultural variations in response or personality styles. Implications for counseling with Asian-American students are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gamma-knife radiosurgery for metastatic brain tumors from primary lung cancer

INTRODUCTION: Improvements of the results of combined chemoradiotherapy (CRT) in esophageal cancer has led several groups to adopt a non surgical attitude specially in case of complete response (endoscopy +/- biopsy). Few information are available about the follow-up of these patients. We studied long-term results of 35 patients who underwent resection after complete response to preoperative chemoradiotherapy. PATIENTS AND METHODS: 161 patients with resecable carcinoma of the thoracic esophagus have received the same protocol of CRT (cisplatin 80 mg/m2, radiation therapy split course: 37.5 Gy) all patients were followed every for 4 months (no lost of view). RESULTS: Complete response (endoscopy and biopsy) was obtained for 35 patients (21.7%), 19 of them (54%) had pathologic complete response (PCR) (no tumor in the specimen), 16 have microscopic foci of residual tumor (46%). The overall 5-year survival rate was 49.8% for the whole group (median survival 64 months), 70% for the group without tumor in the specimen, 48% for the group with microscopic foci of residual tumor (NS). CONCLUSIONS: One half of the complete response (endoscopy + biopsy) have not a pathologic complete response (microscopic foci of residual tumor in the specimen). The 49.8% of five year survival suggests a benefit from esophagectomy for complete response after combined chemoradiotherapy.     

Interfacial tension of demixed polymer solutions over a wide range of reduced temperature

Interfacial tensions were measured for solutions of polystyrene-methylcyclohexane, polystyrene-heptamethylnonane and poly(dimethyl siloxane)-phenylethyl ether to investigate the behaviour of the interfacial tension from the critical point to a region far away from it. In the polystyrene-heptamethylnonane system, measurements were performed until the concentration of the polymer rich phase became about 70～80%. The molecular weight dependence of the interfacial tension was stronger away from the critical temperature than near to it. Data for polystyrene solutions with different solvents were connected by a scaling law. Recent scaling theories were compared with the results for poly(dimethyl siloxane) solution.     

Qualitative analysis of fluorescent whitening agents in river water

The analytical method of fluorescent whitening agents (FWAs) in river waters was examined. Two types of FWAs were identified qualitatively in river waters with the aid of the extraction method developed in the present work and thin layer chromatography.     

Reliability of high radiance InGaAsP/InP LED́s operating in the 1.2-1.3 µm wavelength

The reliability of high radiance InGaAsP/InP DH LED's operating in the1.2-1.3 mum wavelength and the defect structures observed in this quaternary alloy have been presented. Threading dislocations and misfit dislocations do not act as strong nonradiative recombination centers, in contrast with the case in GaAs or GaAlAs optical devices. Dark-spot defects (DSD's) were sometimes generated in the emitting area during aging at elevated temperatures. These defects were analyzed microscopically using a transmission electron microscope and were identified as precipitates. To investigate the homogeneous degradation, accelerated aging at the ambient temperatures of 20, 60, 120, 170, 200, and 230°C has been carried out for over 15 000 h at the current density of 8 kA/cm²using LED's without dark structures. The degradation rates were statistically calculated by assuming the normal distribution. The mean values of degradation rates and the values of standard deviation were determined at the temperatures above 170°C. The activation energy of homogeneous degradation was determined to be 1.0 eV and the extrapolated half-life in excess of 10⁹h was estimated at the ambient temperature of 60°C.