Reflections on the Use of HCI Methods for the Design of Learning Spaces

http://deepblue.lib.umich.edu/bitstream/2027.42/97022/1/Quintana-CHI 2012 Architecture and Interaction.pd

Mixture Design Approach on the Physical Properties of Lignin-Resorcinol-Formaldehyde Xerogels

Organic xerogels were functionalized by incorporating sugarcane bagasse lignin from soda pulping black liquor, not used so far in this materials, with the aim of introducing new functional groups on traditional gels that could improve its adsorptive capacity. Two mixing designs were applied to identify the reactive combinations that allow a well gel formation and to adjust models that predict physical properties. The designs study five components: resorcinol (R, 0.04–0.3), lignin (L, 0.004–0.14), formaldehyde (F, 0.08–0.17), water (W, 0.45–0.8), and NaOH (C, 0.0003–0.0035). The first experimental design was an extreme vertices design and its results showed shrinkage between 4.3 and 59.7 and a bulk density from 0.54 to 1.3; a mass ratio LR/F near 1.5 was required for gel formation. In the second design a D-Optimal was used to achieve better adjusted coefficients and incorporate the largest possible amount of lignin in the gels. Bulk density varies from 0.42 to 0.9, shrinkage varies from 3.42 to 25.35, and specific surface area reaches values of 451.86 m2/g with 13% lignin and 270 m2/g with 27% lignin. High catalyst content improves lignin dissolution and increase shrinkage and bulk density of xerogels and bulk density. Lignin contributes to reducing shrinkage and specific surface area due to his compact and rigid structure

Evaluación de la capacidad de almacenamiento de energía en xerogeles de carbono activados obtenidos a partir lignina

En este trabajo se prepararon dos tipos de xerogeles orgánicos a partir de soluciones sol-gel usando resorcinol (R), formaldehido (F), lignina (L) y NaOH (C) como catalizador. La relación másica L/(R+L) se fijó en 0,27 y el contenido de catalizador se varió en dos relaciones másicas de (R+L)/C, 90,3 (serie G) y 72,1 (serie D). Los xerogeles orgánicos se activaron químicamente con ácido fosfórico a una relación másica de ácido a xerogel de 0,85/1, 1h de impregnación y 2h de activación y una temperatura de activación de 450°C. Los xerogeles de carbono activados se evaluaron electroquímicamente como electrodos para supercondensadores mediante diferentes técnicas como voltamperometría cíclica (VC), cronopotenciometría (CP) y espectroscopía de impedancia electroquímica (EIS) en una configuración de dos y tres electrodos. El valor de la capacidad gravimétrica a partir de las curvas de voltamperometría cíclica a 0,5mV/s (0 – 0,75V) para las muestras activadas GA27 y DA27 fueron 222 y 226F/g, respectivamente. La muestra DA27 mostró una mayor retención de la energía, que es atribuible a un aumento de la presencia de mesoporos en la muestra comparada con la GA27. Los mesoporos s forman debido a la degradación de la lignina en la activación con ácido fosfórico; la muestra DA27 tiene una reticulación superior en comparación con la muestra GA27, ya que el interior del xerogel orgánico es menos accesible. La muestra con mayor contenido de catalizador mostró mejor comportamiento electroquímico para su aplicación como electrodos para supercondensadores.In this work two types of organic xerogels were prepared from sol-gel solutions using resorcinol (R), formaldehyde (F), lignin (L) and NaOH (C) as catalyst. The mass ratio L/(R+L) was set at 0.27 and the amount of catalyst was varied on two mass ratios (R+L)/C, 90.3 (G series) and 72.1 (D series). Organic xerogels are chemically activated with phosphoric acid with a mass ratio of acid to xerogel 0.85/1, 1h of impregnation and 2h of activation and activation temperature is fixed at 450°C. Activated carbon xerogels are electrochemically evaluated as electrodes for supercapacitors using different techniques such as cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS) in a configuration of two and three electrodes. The value of the gravimetric capacity from cyclic voltammetry curves at 0.5mV/s (0 – 0.75V) for samples GA27 and DA27 were 222 and 226F/g, respectively. The DA27 sample showed more retention of energy than GA27, which is attributable to an increase in the presence.Neste trabalho foram preparados dois tipos de xerogéis orgânicos a partir de soluções de sol-gel utilizando o resorcinol (R), formaldeído (F), lignina (L) e NaOH (C) como catalisador. A proporção de massa L/(R+L) foi de 0,27 e o teor de catalisador foi variado em duas proporções de massa (R+L)/C, 90,3(série de G) e 72,1 (série de D). Os xerogéis orgânicos são quimicamente ativados com o ácido fosfórico com uma relação de massa de ácido para o xerogel de 0,85/1, tempos de impregnação e de ativação de uma hora e com uma temperatura de activação de 450°C. Os xerogéis de carbono ativados foram avaliados eletroquimicamente como eletrodos para supercapacitores usando técnicas diferentes, tais como voltametria cíclica (CV), cronopotenciometria (PB) e espectroscopia de impedância eletroquímica (EIS) numa configuração de dois e três eletrodos. O valor da capacidade gravimétrica obtidas das curvas de voltametria cíclica para 0,5mV/s (0 – 0,75V) para as amostras GA27 e DA27 foram de 222 e 226F/g, respetivamente. A amostra DA27 apresentou maior retenção de energia, que é atribuível a um aumento da presença de mesoporos na amostra em comparação com a GA 27. Os mesoporos são formados devido à degradação da lignina na activação com ácido fosfórico; amostra DA27 tem uma maior reticulação comparada com a amostra GA27, já que o interior do xerogel orgânico é menos acessível. A amostra com maior teor de catalisador apresentou melhor desempenho eletroquímico para aplicação como eletrodos para supercapacitores

Low kinetic energy oxygen ion irradiationof vertically aligned carbon nanotubes

International audienceVertically aligned multiwalled carbon nanotubes (v-CNTs) were functionalized with oxygen groups using low kinetic energy oxygen ion irradiation. X-ray photoelectron spectroscopy (XPS) analysis indicates that oxygen ion irradiation produces three different types of oxygen functional groups at the CNTs surface: epoxide, carbonyl and carboxyl groups. The relative concentration of these groups depends on the parameters used for oxygen ion irradiation. Scanning electron microscopy (SEM) shows that the macroscopic structure and alignment of v-CNTS are not affected by the ion irradiation and transmission electron microscopy (TEM) proves tip functionalization of v-CNTs. We observed that in comparison to oxygen plasma treatment, oxygen ion irradiation shows higher functionalization efficiency and versatility. Ion irradiation leads to higher amount of oxygen grafting at the v-CNTs surface, besides different functional groups and their relative concentration can be tuned varying the irradiation parameters

Band bending at In-rich InGaN surfaces

The band bending and carrier concentration profiles as a function of depth below the surface for oxidized InxGa1−xN alloys with a composition range of 0.39 ≤ x ≤ 1.00 are investigated using x-ray photoelectron, infrared reflection, and optical absorption spectroscopies, and solutions of Poisson’s equation within a modified Thomas–Fermi approximation. All of these InGaN samples exhibit downward band bending ranging from 0.19 to 0.66 eV and a high surface sheet charge density ranging from 5.0×1012 to 1.5×1013 cm−2. The downward band bending is more pronounced in the most In-rich InGaN samples, resulting in larger near-surface electron concentrations

Correction: The Genographic Project Public Participation Mitochondrial DNA Database

Correction: The Genographic Project Public Participation Mitochondrial DNA Databas

Planetary Candidates Observed by Kepler VI: Planet Sample from Q1-Q16 (47 Months)

\We present the sixth catalog of Kepler candidate planets based on nearly 4 years of high precision photometry. This catalog builds on the legacy of previous catalogs released by the Kepler project and includes 1493 new Kepler Objects of Interest (KOIs) of which 554 are planet candidates, and 131 of these candidates have best fit radii <1.5 R_earth. This brings the total number of KOIs and planet candidates to 7305 and 4173 respectively. We suspect that many of these new candidates at the low signal-to-noise limit may be false alarms created by instrumental noise, and discuss our efforts to identify such objects. We re-evaluate all previously published KOIs with orbital periods of >50 days to provide a consistently vetted sample that can be used to improve planet occurrence rate calculations. We discuss the performance of our planet detection algorithms, and the consistency of our vetting products. The full catalog is publicly available at the NASA Exoplanet Archive.Comment: 18 pages, to be published in the Astrophysical Journal Supplement Serie