Seismic response control of building structures under pulse-type ground motions by active vibration controller

Active vibration control systems are commonly reported to be the most robust and effective method for vibration control of structures. However, the type of ground motions and the type of analysis may greatly influence their performances. This study investigates the seismic response of building with and without an active controller under pulse-type ground motions. A 20-story non-linear steel benchmark building is considered. Linear and non-linear analysis is conducted to check the effectiveness of the active control system. Active control with a linear quadratic Gaussian (LQG) control algorithm is applied to the benchmark building for seismic control purposes. Initially, some ground motions are selected following earlier studies from the literature concerning the benchmark building. It is found that the LQG control algorithm is quite effective under the considered earthquakes, and the analysis type does not affect the effectiveness of the controller. Thereafter, a set of additional 69 pulse-type ground motions are considered to check the performance of the LQG control algorithm and to find the suitability of linear analysis. It is noticed that under such pulse-type ground motion, the LQG control algorithm is not much effective if the non-linear behavior of the structure is incorporated in the seismic analysis, whereas in case of linear analysis, the LQG control algorithm is still effective. It is concluded that neglecting the non-linear behavior may lead to unconservative estimates of the seismic response when performing seismic analysis and designing structures equipped with active vibration control systems.</p

Electrodeposition of 4,4′-di-tert-butylbiphenyl peroxide from the anodic oxidation of p-tert-butylphenol in an alkaline acetonitrile solution

The electrogeneration of pure 4,4′-di-tert-butylbiphenyl peroxide as an electrodeposit could be achieved on a platinum electrode through the anodic oxidation of p-tert butylphenol in the presence of Lutidine, in addition to several soluble oligomers. The electrochemical and theoretical studies have shown that the favored coupling reaction corresponds to the O–O bond, albeit it is generally being considered unstable. Without the strong base, a mixture of trimer, tetramer and pentamer was deposited. The peroxide product presents a different electroactivity to that of the phenolic compound, with the appearance of a redox process involving cathodic and anodic symmetrical peaks at −0.10/0.15 V versus SCE, which indicates the preference of the polymer to adhere onto the electrode surface. The thermal degradation has also been analyzed. Quantum-chemical calculations reveal the reason for the oxygen–oxygen coupling.The authors would like to thank the Tunisian Ministry of Higher Education and Research for its financial support as well as the King Saud University for its funding through the Research Group Project No RGP-VPP-243. They would also like to thank the Spanish Ministry of Economy and Competitiveness for its financial support and the STIs for the ERDF funds (MAT2013-42007-P) and the Generalitat Valenciana (PROMETEO2013/ 038)

Electrochemical and spectral studies of auto-assembled arrays of calix[4]arenequinhydrone charge-transfer complex on indium-tin oxide (ITO) glass.

A sensing materiel based on calix[4]arene molecules is electrochemically deposited on ITO electrode coated. A brown film was electrodeposited at a potential Eimp&nbsp;=&nbsp;-1.00&nbsp;V versus SCE in acetonitrile solvent, however in dichloromethane solvent, a bluish film auto-assembled on the ITO electrode coated at a potential Eimp&nbsp;=&nbsp;-0.65&nbsp;V versus SCE. Both films are subsequently analyzed by cyclic voltammetry and UV-Vis spectroscopy. This investigation shows that in acetonitrile solvent, the charge-transfer complex, calix[4]arenequinhydrone was formed in electrolytic solution and it was not self-assembled on the ITO electrode. The related UV-Vis spectrum shows a single absorption band towards a wavelength about 350&nbsp;nm. The optical behaviour of the blue film shows two absorption bands: the first one appears on the first absorption band of the acceptor at 305&nbsp;nm and the second one in the visible range at 502&nbsp;nm. The band situated in the visible range correspond to a well-defined charge-transfer band indicating the presence of the charge-transfer complex, the calix[4]arenequinhydrone

Review of Vibration Control Strategies of High-Rise Buildings

Since the early ages of human existence on Earth, humans have fought against natural hazards for survival. Over time, the most dangerous hazards humanity has faced are earthquakes and strong winds. Since then and till nowadays, the challenges are ongoing to construct higher buildings that can withstand the forces of nature. This paper is a detailed review of various vibration control strategies used to enhance the dynamical response of high-rise buildings. Hence, different control strategies studied and used in civil engineering are presented with illustrations of real applications if existing. The main aim of this review paper is to provide a reference-rich document for all the contributors to the vibration control of structures. This paper will clarify the applicability of specific control strategies for high-rise buildings. It is worth noting that not all the studied and investigated methods are applicable to high-rise buildings; a few of them remain limited by many parameters such as cost-effectiveness and engineering-wise installation and maintenance

Electrochemical and spectral studies of auto-assembled arrays of calix[4]arenequinhydrone charge-transfer complex on indium–tin oxide (ITO) glass

A sensing materiel based on calix[4]arene molecules is electrochemically deposited on ITO electrode coated. A brown film was electrodeposited at a potential Eimp = -1.00 V versus SCE in acetonitrile solvent, however in dichloromethane solvent, a bluish film auto-assembled on the ITO electrode coated at a potential Eimp = -0.65 V versus SCE. Both films are subsequently analyzed by cyclic voltammetry and UV-Vis spectroscopy. This investigation shows that in acetonitrile solvent, the charge-transfer complex, calix[4]arenequinhydrone was formed in electrolytic solution and it was not self-assembled on the ITO electrode. The related UV-Vis spectrum shows a single absorption band towards a wavelength about 350 nm. The optical behaviour of the blue film shows two absorption bands: the first one appears on the first absorption band of the acceptor at 305 nm and the second one in the visible range at 502 nm. The band situated in the visible range correspond to a well-defined charge-transfer band indicating the presence of the charge-transfer complex, the calix[4]arenequinhydrone

Influence of drying plant material on yield, chemical composition, antioxidant and anti-inflammatory activities of essential oil extracted from the Tunisian Cupressus sempervirens leaves.

peer reviewedThe present study aims to assess the effectiveness of the drying time on the yield, chemical composition, antioxidant and anti-inflammatory properties of the essential oils (EOs) obtained from the Tunisian Cupressus sempervirens leaves. Adequate oils extraction conditions were determined. The drying time affected significantly the EOs yield of this plant. The major compounds found were; α-pinene, β-selinene, δ-3-carene, α-cubebene, β-caryophyllene and α-cedrol. Also, oils extracted from dried (60 and 90 days) leaves have high antioxidant properties due to the high content of (α-pinene and β-caryophyllene). Those constituents were known for their antioxidant activities. For the anti-inflammatory study, the inhibition was higher for the 60 days of drying at 100 μg mL-1. Keywords— Cupressus sempervirens; leaf; essential oils; Microwave-assisted hydrodistillation; antioxidant activity; anti-inflammator

Preparation of cypress (Cupressus sempervirens L.) essential oil loaded poly(lactic acid) nanofibers

This study investigated the production of poly (lactic acid) (PLA) nanofibers containing cypress (CUP) essential oil (EO) via electrospinning. The nanofibers were produced from polymer solution prepared with different percentages of cypress EO. Cypress EO-containing PLA nanofibers were characterized and some mechanical and thermal properties were examined using thermo-gravimetric analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, and dynamic mechanical analysis. The thermal stability of the nanofibers was reduced depending on the percentage of the cypress EO. As the ratio of the cypress EO to polymer matrices was increased, it was observed that the glassy transition temperatures of the nanofibers decreased and their flexibility increased. The T-g value was determined to be 53.74 degrees C for the neat PLA nanofiber, while 51.83 degrees C for the PLA-CUP nanofiber (containing 15% cypress EO). According to the results of releasing trial, the increased amount of cypress EO resulted in less cypress EO releasing from polymer matrices. The nanofibers were observed to exhibit antibacterial activity against Escherichia coli and Staphylococcus aureus. The inhibition zone diameter of the nanofibers containing 10% cypress EO was 20 mm for S. aureus and 16 mm for E. coli, while 10 mm in the presence of Kanamycin

Impaired Control of Effector T Cells by Regulatory T Cells: A Clue to Loss of Oral Tolerance and Autoimmunity in Celiac Disease?

International audienceOBJECTIVES:Regulatory T cells (Tregs) are instrumental for tolerance to self-antigens and dietary proteins. We have previously shown that interleukin (IL)-15, a cytokine overexpressed in the intestine of patients with celiac disease (CD), does not impair the generation of functional Tregs but renders human T cells resistant to Treg suppression. Treg numbers and responses of intestinal and peripheral T lymphocytes to suppression by Tregs were therefore compared in CD patients and controls.METHODS:Intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) were isolated from duodenal biopsy specimens of CD patients and controls. Concomitantly, CD4+CD25+ T lymphocytes (Tregs) were purified from blood. Responses of IELs and of LPLs, and peripheral lymphocytes (PBLs) to suppression by Tregs were tested by analyzing anti-CD3-induced proliferation and interferon (IFN)-γ production in the presence or absence of peripheral Tregs. Lamina propria and peripheral CD4+CD25+FOXP3+ T cells were assessed by flow cytometry.RESULTS:Although percentages of CD4+CD25+FOXP3+ LPLs were significantly increased in patients with active CD, proliferation and IFN-γ production of intestinal T lymphocytes were significantly less inhibited by autologous or heterologous Tregs in CD patients than in controls (P<0.01). In all tested CD patients, IEL were unable to respond to Tregs. Resistance of LPLs and PBLs to Treg suppression was observed in patients with villous atrophy who had significantly enhanced serum levels of IL-15 compared with patients without villous atrophy and controls.CONCLUSIONS:Our results indicate that effector T lymphocytes from active CD become resistant to suppression by Tregs. This resistance might cause loss of tolerance to gluten, but also to self-antigens.Am J Gastroenterol advance online publication, 22 November 2011; doi:10.1038/ajg.2011.397