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Roughness influence on the sheet resistance of the PEDOT:PSS printed on paper
Rogerio M. Morais,Maykel S. Klem,Maíza S. Ozorio,Tiago C. Gomes,Neri Alves 한국물리학회 2018 Current Applied Physics Vol.18 No.2
The use of paper as a platform to manufacture organic electronic devices, electronic paper, has expanding potential for many applications because of several properties offered. In this work, we show a study of PEDOT:PSS printed by inkjet on bond paper, vegetal paper and sheets of PET. The relation between the surface density of the deposited material, morphology and resistivity was investigated for samples printed with a commercial Hewlett-Packard(HP)® printer and Microsoft Word® software. The amount of material deposited, i.e. surface density, was controlled using the print number in the same position and changing the gray scale used in the image formation. Changing the surface density of printed PEDOT:PSS, it is possible to produce a continuous film permeating the papers fibers. Sheet resistances obtained, when 7.0 mg cm−2 of PEDOT:PSS were deposited on the surfaces, were: (a) 413.2 kΩ/Sq for bond paper, (b) 5.6 kΩ/Sq for vegetable paper and (c) 2.3 kΩ/Sq for PET. The exponential dependence of sheet resistance with the surface density of printed material allows us to evaluate the strong influence of substrate roughness on PEDOT:PSS conductivity and to predict, for each one, conditions to minimize it.
Paraffin-based ramjet missile preliminary design
Rogerio L.V. Cruz,Carlos A.G. Veras,Olexiy Shynkarenko Techno-Press 2023 Advances in aircraft and spacecraft science Vol.10 No.4
This paper presents a basic methodology and a set of numerical tools for the preliminary design of solid-fueled ramjet missiles. An elementary code determines the baseline system configuration comprised of warhead, guidance-control, and propulsion masses and geometries from specific correlations found in the literature. Then, the system is refined with the help of external and internal ballistics codes. Equations of motion are solved for the flight's ascending, cruising, and descending stages and the internal ballistic set of equations designs the ramjet engine based on liquefying fuels. The combined tools sized the booster and the ramjet sustainer engines for a long-range missile, intended to transport 200 kg of payload for more than 300 km range flying near 14,000 m altitude at Mach 3.0. The refined system configuration had 600 mm in diameter and 8,500 mm in length with overall mass of 2,128 kg and 890 kg/m3 density. Ramjet engine propellant mass fraction was estimated as 74%. Increased missile range can be attained with paraffin-polyethylene blend burning at near constant regression rate through primary air mass flow rate control and lateral 2-D air intakes.
Rodrigo Rogerio Cerqueira da Silva,Raquel Gonçalves,Cinthya Bertoldo 한국콘크리트학회 2024 International Journal of Concrete Structures and M Vol.18 No.2
The use of nondestructive techniques in the technological control of concrete allows to evaluate and monitor the condition of the material without interfering with its properties; therefore, it is highly desirable in on-site inspections. Among these techniques, ultrasonic testing stands out as one of the most promising by its speed and simplicity to obtain results. However, inferences of strength and stiffness properties using ultrasound parameters should be made with caution, since many factors may interfere with wave propagation. This research aimed to evaluate the behavior of parameters obtained by ultrasonic testing (velocity of wave propagation [V] and stiffness coefficient [C = density × V2]) as predictors of the strength (fc) and stiffness (Eci) of concrete produced with coarse aggregates from different mineralogical origins. To achieve the objective, 128 specimens were produced with four aggregate mineralogical origins and four water-cement ratios, with 8 replications each. The ultrasonic tests were performed with two-frequency transducers (45 and 80 kHz). Prediction models of fc and Eci were statistically significant (P-value < 0,05) for both frequencies. The model using [C] as independent variable present better correlation with Eci (R2 > 91,2%) and with fc (R2 > 82%) than the model using only [V]. General regression models (regardless of the gravel type) were also statistically significant (P-value < 0.05), with R2 > 79% and prediction errors higher than those obtained for the specific models for different rock types.
Experimental investigation of local damage in high strength concrete columns using a shaking table
Bairrao, Rogerio,Kacianauskas, Rimantas,Kliukas, Romualdas Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.5
In this paper the accumulation of local damage during the cyclic loading in reinforced high-strength concrete columns is experimentally investigated. Two identical column specimens with annular cross-section and spiral reinforcement were designed and two tests, up to failure, under the action of a constant vertical concentrated force and a time-dependent concentrated horizontal force, were carried out at the LNEC shaking tables facility. Sine type signals, controlled in amplitude, frequency and time duration were used for these experiments. The concept of local damage based on local stiffness degradation is considered in detail and illustrated by experimental results. The specimens were designed and reinforced in such a way that the accumulation of damage was predicted by dominating deformations (cracking and crushing of the concrete) while the increasing of the loading values was a dominating factor of damage. It was observed that the local damage of HSC columns has exposed their anisotropic local behaviour. The damage accumulation was slightly different from the expected in accordance with the continuum damage concept, and a partial random character was observed.
Washington Rogerio de Sousa,Bruno Henrique Lopes Botelho Lourenc¸o,Michelle de Paula Reis,Guilherme Donadel,Marcia Alessandra Arantes Marques,Euclides Lara Cardozo Junior,Ezilda Jacomassi,Salviano Tra 한국식품영양과학회 2019 Journal of medicinal food Vol.22 No.1
Yerba mate (Ilex paraguariensis A. St.-Hil.; Aquifoliaceae) is a popular tonic and stimulant beverage that is widely consumed in different South American countries. Estimates indicate the consumption of >1 L per day in southern Brazil and Uruguay. Despite its relatively high consumption, data on reproductive toxicity during critical periods of gestation remain unclear. Thus, we evaluated the effects of an aqueous extract of I. paraguariensis leaves (“chimarrão” [IPC]) at two critical periods of gestation in Wistar rats: preimplantation embryonic stage and fetal organogenesis. Pregnant Wistar rats were orally treated with IPC (3, 30, and 300 mg/kg) from days 1 to 7 or 8 to 21 of pregnancy. The respective control groups received vehicle. During treatment, clinical signs of maternal toxicity, maternal body weight, and food and water intake were monitored. The rats were killed on days 8 and 20 of pregnancy, and the following parameters were evaluated: weight of the maternal uterus, weight of the liver, weight of the kidneys, weight of the spleen, total embryo implantation, preimplantation loss, the mean of live fetuses, the percentage of dead fetuses, fetus weight, and fetal malformation. The aqueous extract of the leaves of I. paraguariensis L. did not present any deleterious effects on preimplantation embryos or the organogenesis of offspring from female Wistar rats. These safety data provide evidence that IPC may be safe for consumption during gestation.
( Paulo Gustavo Kotze ),( Rogerio Saad Hossne ) 대한장연구학회 2013 Intestinal Research Vol.11 No.4
In most patients, postoperative endoscopic recurrence (PER) occurs 1 year after abdominal resection for Crohn`s disease (CD). Preventing PER is essential for disease control, as most patients develop further clinical and surgical recurrences. Conventional therapy with nitroimidazoles, aminosalicylates, and immunomodulators have limited efficacy for preventing PER. Initial trials with biological therapy (infliximab and adalimumab) showed promising results in preventing PER, and the efficacy of these drugs seems higher than that with conventional therapy. The aim of this review is to outline the results of studies that used infliximab or adalimumab for preventing and treating PER in CD patients. Data with both agents are available, and a few, small prospective trials have shown the efficacy of these drugs in patients with a high risk for recurrence. We believe that, in 2013, biological agents will be better accepted for the prevention PER in CD patients, in addition to the already existing data. Larger trials are still underway, and their results will certainly determine the role of these agents in PER, which develops after bowel resection for CD. (Intest Res 2013;11:256-260)