Measurements of coupling and reflection characteristics of butt-joints in passive waveguide integrated laser diodes

Amplified spontaneous emission (ASE) spectra of passive waveguide integrated lasers have been studied to estimate the coupling efficiency and the reflectivity at the butt-joints between active and passive waveguides. A new method has been proposed for the analysis of ASE to extract the coupling efficiency and reflectivity at the butt-joints. This method was applied experimentally to estimate the coupling and reflection of the passive waveguide integrated lasers with different amounts of vertical misalignments of active and passive waveguides.     

A software-based sensor for combined sewer overflows

A new methodology for online estimation of excess flow from combined sewer overflow (CSO) structures based on simulation models is presented. If sufficient flow and water level data from the sewer system is available, no rainfall data are needed to run the model. An inverse rainfall-runoff model was developed to simulate net rainfall based on flow and water level data. Excess flow at all CSO structures in a catchment can then be simulated with a rainfall-runoff model. The method is applied to a case study and results show that the inverse rainfall-runoff model can be used instead of missing rain gauges. Online operation is ensured by software providing an interface to the SCADA-system of the operator and controlling the model. A water quality model could be included to simulate also pollutant concentrations in the excess flow.     

Deposition of tellurium films by decomposition of electrochemically-generated H2Te: application to radiative cooling devices

The preparation of homogenous, large area thin layers of tellurium on thin polyethylene foils is described. The tellurium was formed by room temperature decomposition of electrochemically generated H₂Te. Pre-treatment of the polyethylene substrates with KMnO₄ to give a Mn-oxide layer was found to improve the Te adhesion and homogeneity. Optical characterization of the layers was performed using UV/VIS/NIR spectroscopy. Such coatings have favorable characteristics for use as solar radiation shields in radiative cooling devices. The simplicity of generation of the very unstable H₂Te was also exploited to demonstrate formation of size-quantized CdTe nanocrystals.     

Oxidation of H2S by iron oxides in unsaturated conditions

Previous studies have demonstrated that gas-phase H2S can immobilize certain redox-sensitive contaminants (e.g., Cr, U, Tc) in vadose zone environments. A key issue for effective and efficient delivery of H2S in these environments is the reactivity of the gas with indigenous iron oxides. To elucidate the factors that control the transport of H2S in the vadose zone, laboratory column experiments were conducted to identify reaction mechanisms and measure rates of H2S oxidation by iron oxide-coated sands using several carrier gas compositions (N2, air, and O2) and flow rates. Most experiments were conducted using ferrihydrite-coated sand. Additional studies were conducted with goethite- and hematite-coated sand and a natural sediment. Selective extractions were conducted at the end of each column experiment to determine the mass balance of the reaction products. XPS was used to confirm the presence of the reaction products. For column experiments in which ferrihydrite-coated sand was the substrate and N2 was the carrier gas, the major H2S oxidation products were FeS and elemental sulfur (mostly S8(0), represented as S(0) for simplicity) at ratios that were consistent with the stoichiometry of the postulated reactions. When air or O2 were used as the carrier gas, S(0) became the dominant reaction product along with FeS2 and smaller amounts of FeS, sulfate, and thiosulfate. A mathematical model of reactive transport was used to test the hypothesis that S(0) forming on the iron oxide surfaces reduces access of H2S to the reactive surface. Several conceptual models were assessed in the context of the postulated reactions with the final model based on a linear surface poisoning model and fitted reaction rates. These results indicate that carrier gas selection is a critical consideration with significant tradeoffs for remediation objectives.     

Quantifying ethanol content of beer using interpretive near-infrared spectroscopy

On the basis of absorption measurements in the near-infrared (NIR) spectral range, a new method for the quantification of the ethanol content of beer is presented. Instead of the multivariate calibration models most commonly employed in NIR spectroscopic works, we use interpretive difference spectroscopy: Two wavelengths are selected according to the assignment of the absorption bands of the main substances of content of beer in the NIR region, and the difference between the absorbances at these wavelengths is used for ethanol quantification. Absorption spectra of the dominating beer ingredients are discussed and the calibration procedure with ethanol/water mixtures is shown. Robustness against the carbohydrate content of beer samples was demonstrated by analyzing solutions of ethanol and maltose in water. Validation of the method was performed with various beer samples with an ethanol concentration range between 0.5 and 7.7 vol %. The pertinent advantage of the procedure developed in this work is the indication that the results are independent from seasonal variations of the ingredients, which is of high interest for products with natural ingredients such as beer.     

Historical view of the influences of measurement and reading theories on the assessment of reading

The purpose of this study is to briefly explore the interactions among measurement theories, reading theories, and measurement practices from an historical perspective. The assessment of reading provides a useful framework for examining how theories influence, and in some cases fail to influence, the practice of reading assessment as operationalized in reading tests. The first section describes a conceptual framework for examining the assessment of reading. Next I describe the major research traditions in measurement theory that have dominated measurement practice during the 20th century. In the next section I briefly introduce major reading theories. Next, I bring together the previous two sections in order to examine the adequacy of the proposed conceptual framework for examining the assessment of reading. This section includes criticism of measurement theory by selected reading theorists. It also provides a brief history of the use of Rasch measurement theory to calibrate reading tests. Finally, the main points of the study are summarized and discussed. It should be recognized that this study represents a preliminary analysis of these issues.     

Synthesis of SiC nanorods from bleached wood pulp

Unbleached and bleached soft wood pulps have been used as templates and carbon precursors to produce SiC nanorods. Hydrolyzed tetraethylorthosilicate (TEOS), silicic acid was infiltrated into the pulps followed by a carbothermal reduction to form SiC nanorods at 1400 °C in Ar. Residual carbon formed along with SiC was removed by gasification at 700 °C in air. The SiC materials prepared from unbleached pulp were non-uniform SiC with a thick SiO₂ coating, while the SiC nanorods prepared from the bleached pulp were uniform and straight with dimensions of 250 nm in diameter and 5.0 mm long. The formation of uniform camelback structure of SiC in the reaction between silica and bleached pulp is attributed to more silica deposited in the amorphous region of cellulose.     

Comparisons of mathematics achievement of grade 8 students in the United States and the Russian Federation

Using the Mantel-Haenszel (MH) Procedure, we analyzed data for 7,087 American and 4,022 Russian Grade 8 students from the Third International Mathematics and Science Study (TIMSS) to compare mathematics achievement in the two countries on each of the 124 multiple-choice items. The results of the analyses indicate that the performance of the students on individual multiple-choice mathematics items vary by country. The results also suggest that the relationship between country and item performance differ as a function of content area. A total score of a country's achievement does not provide the whole picture of achievement dynamics; it averages out potentially important information on student achievement and the causes of their performance relative to other countries. The dynamics of achievement across countries will not be revealed unless the analyses are done at the item level.     

Fluorescent dye encapsulated ZnO particles with cell-specific toxicity for potential use in biomedical applications

Fluorescein isothiocyanate (FITC)-encapsulated SiO₂ core-shell particles with a nanoscale ZnO finishing layer have been synthesized for the first time as multifunctional “smart” nanostructures. Detailed characterization studies confirmed the formation of an outer ZnO layer on the SiO₂–FITC core. These ~200 nm sized particles showed promise toward cell imaging and cellular uptake studies using the bacterium Escherichia coli and Jurkat cancer cells, respectively. The FITC encapsulated ZnO particles demonstrated excellent selectivity in preferentially killing Jurkat cancer cells with minimal toxicity to normal primary immune cells (18% and 75% viability remaining, respectively, after exposure to 60 μg/ml) and inhibited the growth of both gram-positive and gram-negative bacteria at concentrations ≥250–500 μg/ml (for Staphylococcus aureus and Escherichia coli, respectively). These results indicate that the novel FITC encapsulated multifunctional particles with nanoscale ZnO surface layer can be used as smart nanostructures for particle tracking, cell imaging, antibacterial treatments and cancer therapy.     

Home environment and the competitiveness of highly accomplished individuals in four talent fields.

This study explores the relationship between home environment and the competitiveness of highly accomplished individuals in 4 different talent fields (world-class tennis players, Olympic swimmers, award-winning concert pianists, and eminent research mathematicians). A secondary analysis was made of interview protocols collected as a part of the Development of Talent Project (B. S. Bloom, 1985). Results indicate that individuals from home environments in which competitiveness is valued, modeled, and rewarded tend to be more competitive, r(30)?=?.68, p?