Nanostructures on spin-coated polymer films controlled by solvent composition and polymer molecular weight

In this study we systematically investigated how the solvent composition used for polymer dissolution affects the porous structures of spin-coated polymers films. Cellulose acetate butyrate (CAB) and poly(methylmethacrylate) with low(PMMA-L) and high (PMMA-H) molecular weights were dissolved in mixtures of acetone (AC) and ethyl acetate (EA) at constant polymer concentration of 10 g/L The films were spin-coated at a relative air humidity of 55+/-5%, their thickness and index of refraction were determined by means of ellipsometry and their morphology was analyzed by atomic force microscopy. The dimensions and frequency of nanocavities on polymer films increased with the acetone content (phi(AC)) in the solvent mixture and decreased with increasing polymer molecular weight. Consequently, as the void content increased in the films, their apparent thicknesses increased and their indices of refraction decreased, creating low-cost anti-reflection surface. The void depth was larger for PMMA-L than for CAB. This effect was attributed to different activities of EA and AC in CAB or PMMA-L solution, the larger mobility of chains and the lower polarity of PMMA-L in comparison to CAB. (C) 2012 Elsevier B. V. All rights reserved.

Unmanned platform for long-range remote analysis of volatile compounds in air samples

This paper describes a long-range remotely controlled CE system built on an all-terrain vehicle. A four-stroke engine and a set of 12-V batteries were used to provide power to a series of subsystems that include drivers, communication, computers, and a capillary electrophoresis module. This dedicated instrument allows air sampling using a polypropylene porous tube, coupled to a flow system that transports the sample to the inlet of a fused-silica capillary. A hybrid approach was used for the construction of the analytical subsystem combining a conventional fused-silica capillary (used for separation) and a laser machined microfluidic block, made of PMMA. A solid-state cooling approach was also integrated in the CE module to enable controlling the temperature and therefore increasing the useful range of the robot. Although ultimately intended for detection of chemical warfare agents, the proposed system was used to analyze a series of volatile organic acids. As such, the system allowed the separation and detection of formic, acetic, and propionic acids with signal-to-noise ratios of 414, 150, and 115, respectively, after sampling by only 30 s and performing an electrokinetic injection during 2.0 s at 1.0 kV.

Relationships of Photosynthetic Photon Flux Density, air Temperature and Humidity with Tomato Leaf Diffusive Conductance and Temperature

The objective was to study the leaf temperature (LT) and leaf diffusive vapor conductance (gs) responses to temperature, humidity and incident flux density of photosynthetically active photons (PPFD) of tomato plants grown without water restriction in a plastic greenhouse in Santa Maria, RS, Brazil. The plants were grown in substrate and irrigated daily. The gs was measured using a steady-state null-balance porometer on the abaxial face of the leaves during the daytime. Both leaf surfaces were measured in one day. The PPFD and LT were measured using the porometer. Leaf temperature was determined using an infrared thermometer, and air temperature and humidity were measured using a thermohygrograph. The leaves on the upper layer of the plants had higher gs than the lower layer. The relationship between the gs and PPFD was different for the two layers in the plants. A consistent relationship between the gs and atmospheric water demand was observed only in the lower layer. The LT tended to be lower than the air temperature. The mean value for the gs was 2.88 times higher on the abaxial than adaxial leaf surface.

Application of the Z-scan technique to determine the optical Kerr coefficient and two-photon absorption coefficient of magnetite nanoparticles colloidal suspension

We investigate the occurrence of the optical Kerr effect and two-photon absorption when an oil-based magnetic Fe3O4 nanoparticles colloidal suspension is illuminated with high intensity femtosecond laser pulses. The frequency of the pulses is controlled and the Z-scan technique is employed in our measurements of the nonlinear optical Kerr coefficient (n(2)) and two-photon absorption coefficient (beta). From these values it was possible to calculate the real and imaginary parts of the third-order susceptibility. We observed that increasing the pulse frequency, additional physical processes take place, increasing artificially the absolute values of n(2) and beta. The experimental conditions are discussed to assure the obtention of reliable values of these nonlinear optical parameters, which may be useful in all-optical switching and optical power limiting applications. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4723829]

Diaphragmatic Breathing Training Program Improves Abdominal Motion During Natural Breathing in Patients With Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

Yamaguti WP, Claudino RC, Neto AP, Chammas MC, Gomes AC, Salge TM, Moriya HT, Cukier A, Carvalho CR. Diaphragmatic breathing training program improves abdominal motion during natural breathing in patients with chronic obstructive pulmonary disease: a randomized controlled trial. Arch Phys Med Rehabil 2012;93:571-7. Objective: To investigate the effects of a diaphragmatic breathing training program (DBTP) on thoracoabdominal motion and functional capacity in patients with chronic obstructive pulmonary disease. Design: A prospective, randomized controlled trial. Setting: Academic medical center. Participants: Subjects (N=30; forced expiratory volume in Is, 4270 +/- 13% predicted) were randomly allocated to either a training group (TG) or a control group (CG). Interventions: Subjects in the TG completed a 4-week supervised DBTP (3 individualized weekly sessions), while those in the CG received their usual care. Main Outcome Measures: Effectiveness was assessed by amplitude of the rib cage to abdominal motion ratio (RC/ABD ratio) (primary outcome) and diaphragmatic mobility (secondary outcome). The RC/ABD ratio was measured using respiratory inductive plethysmography during voluntary diaphragmatic breathing and natural breathing. Diaphragmatic mobility was measured by ultrasonography. A 6-minute walk test and health-related quality of life were also evaluated. Results: Immediately after the 4-week DBTP, the TG showed a greater abdominal motion during natural breathing quantified by a reduction in the RC/ABD ratio when compared with the CG (F=8.66; P<.001). Abdominal motion during voluntary diaphragmatic breathing after the intervention was also greater in the TG than in the CG (F=4.11; P<.05). The TG showed greater diaphragmatic mobility after the 4-week DBTP than did the CG (F=15.08; P<.001). An improvement in the 6-minute walk test and in health-related quality of life was also observed in the TG. Conclusions: DBTP for patients with chronic obstructive pulmonary disease induced increased diaphragm participation during natural breathing, resulting in an improvement in functional capacity.

Relationships of photosynthetic photon flux density, air temperature and humidity with tomato leaf diffusive conductance and temperature

The objective was to study the leaf temperature (LT) and leaf diffusive vapor conductance (gs) responses to temperature, humidity and incident flux density of photosynthetically active photons (PPFD) of tomato plants grown without water restriction in a plastic greenhouse in Santa Maria, RS, Brazil. The plants were grown in substrate and irrigated daily. The gs was measured using a steady-state null-balance porometer on the abaxial face of the leaves during the daytime. Both leaf surfaces were measured in one day. The PPFD and LT were measured using the porometer. Leaf temperature was determined using an infrared thermometer, and air temperature and humidity were measured using a thermohygrograph. The leaves on the upper layer of the plants had higher gs than the lower layer. The relationship between the gs and PPFD was different for the two layers in the plants. A consistent relationship between the gs and atmospheric water demand was observed only in the lower layer. The LT tended to be lower than the air temperature. The mean value for the gs was 2.88 times higher on the abaxial than adaxial leaf surface.