Microwave assisted synthesis of gold nanoparticles and their antibacterial activity against <i>Escherichia coli</i> (<i>E. coli</i>)

Arshi, Nishat,Ahmed, Faheem,Kumar, Shalendra,Anwar, M.S.,Lu, Junqing,Koo, Bon Heun,Lee, Chan Gyu Elsevier 2011 Current Applied Physics Vol.11 No.1

<P><B>Abstract</B></P><P>We report a simple one step microwave irradiation method for the synthesis of gold nanoparticles using citric acid as reducing agent and cetyl trimethyl ammonium bromide (CTAB) as binding agent. The reaction was completed under two different microwave irradiation times (40 s and 70 s) for the production of two types of gold nanoparticles. The synthesized nanoparticles were characterized using UV–Vis absorption spectroscopy and transmission electron microscopy (TEM) measurements. UV–Vis study revealed the formation of gold nanoparticles with surface plasmon absorption maxima at 590 and 560 nm for 40 and 70 s irradiation time respectively. From TEM analysis, it is observed that the gold nanoparticles have spherical shape with particle size distribution in the range 1–10 nm and 1–2 nm for 40 s and 70 s irradiation time respectively. Antibacterial activity of gold nanoparticles as a function of particle concentration against gram-negative bacterium <I>Escherichia coli</I> (<I>E. coli</I>) was carried out in solid growth media. The two types of gold nanoparticles show high antibacterial activity with zone of inhibition of about 22 mm against <I>E. coli</I> (ATCC 25922 strain). Very small difference in the antibacterial activity for the two types of gold nanoparticles were observed. Though nanoparticles synthesized for 70 s irradiation time show slightly better antibacterial activity.</P> <P><B>Highlights</B></P><P>► Gold nanoparticles have been successfully synthesized using microwave irradiation technique. ► The mean diameter was ∼ 4.05 nm for 40 s and ∼1.05 nm for 70 s. ► Characteristic absorption peak was found to be 590 nm for 40 s and 560 nm for 70 s. ► The zone of inhibition for the two types of nanoparticles was almost similar (22 mm). ► Smaller size nanoparticles synthesized for 70s showed a slightly better antibacterial action.</P>

Hysteretic behavior of dissipative welded fuses for earthquake resistant composite steel and concrete frames

Luís Calado,Jorge M. Proenca,Miguel Espinha,Carlo A. Castiglioni 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.6

In recent years there has been increasing international interest about designing structures thatcost less to repair after they have been subjected to strong earthquakes. Considering this interest, aninnovative repairable fuse device has been developed for dissipative beam-to-column connections inmoment-resisting composite steel and concrete frames. The seismic performance of the device was assessedthrough an extensive experimental program comprising ten cyclic and two monotonic tests. These tests wereconducted on a single beam-to-column specimen with different fuse devices for each test. The devicesvaried in terms of the chosen geometric and mechanical parameters. The tests showed that the devices wereable to concentrate plasticity and to dissipate large amounts of energy through non-linear behavior.Numerical models were developed with Abaqus and simplified design models are also proposed.

Ovarian teratoma removed by laparoscopic ovariectomy in a dog

Inês T. Tavares,Ramón R. Barreno,José P. Sales-Luís,Carlo G. Vaudano 대한수의학회 2018 Journal of Veterinary Science Vol.19 No.6

An elective laparoscopic ovariectomy on a healthy dog revealed a cystic structure in the left ovary. The surgical procedure was successful. Histopathological examination showed the presence of a teratoma adjacent to the ovary. To the best of the authors’ knowledge, this is the first reported case of an ovarian teratoma removed by laparoscopic ovariectomy in a dog by using a multiport laparoscopic ovariectomy technique.

Functional capacity and ventilatory efficiency are preserved in well-controlled people living with human immunodeficiency virus/acquired immunodeficiency syndrome

Luís Fernando Deresz,Marlus Karsten,Isadora Faraco Corrêa,Anelise Sonza,Maria Letícia Rodrigues Ikeda,Candissa Silva da Silva,Pedro Dal Lago 한국운동재활학회 2018 JER Vol.14 No.4

Prestressed concrete beams under torsion-extension of the VATM and evaluation of constitutive relationships

Luís F.A. Bernardo,Jorge M.A. Andrade 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.5

A computing procedure is presented to predict the ultimate behavior of prestressed beams under torsion. This computing procedure is based on an extension of the Variable Angle Truss-Model (VATM) to cover both longitudinal and transversal prestressed beams. Several constitutive relationships are tested to model the behavior of the concrete in compression in the struts and the behavior of the reinforcement in tension (both ordinary and prestress). The theoretical predictions of the maximum torque and corresponding twist are compared with some results from reported tests and with the predictions obtained from some codes of practice. One of the tested combinations of the relationships for the materials was found to give simultaneously the best predictions for the resistance torque and the corresponding twist of prestressed beams under torsion. When compared with the predictions from some codes of practice, the theoretical model which incorporates the referred combination of the relationships provides best values for the torsional strength and leads to more optimized designs.

Parametric analysis and torsion design charts for axially restrained RC beams

Luís F.A. Bernardo,Cátia S.B. Taborda,Jorge M.R. Gama 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.1

This article presents a theoretical parametric analysis on the ultimate torsional behaviour of axially restrained reinforced concrete (RC) beams. This analysis is performed by using a computing procedure based on a modification of the Variable Angle Truss Model. This computing procedure was previously developed to account for the influence of the longitudinal compressive stress state due to the axial restraint conditions provided by the connections of the beams to other structural members. The presented parametric study aims to check the influence of some important variable studies, namely: torsional reinforcement ratio, compressive concrete strength and axial restraint level. From the results of this parametric study, nonlinear regression analyses are performed and some design charts are proposed. Such charts allow to correct the resistance torque of RC beams (rectangular sections with small height to width ratios) to account for the favorable influence of the axial restraint.

Delay Dependent Local Stabilization Conditions for Time-delay Nonlinear Discrete-time Systems Using Takagi-Sugeno Models

Luís F. P. Silva,Valter J. S. Leite,Eugênio B. Castelan,Gang Feng 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.3

We propose convex conditions for stabilization of nonlinear discrete-time systems with time-varying delay in states through a fuzzy Takagi-Sugeno (T-S) modeling. These conditions are developed from a fuzzy Lyapunov-Krasovskii function and they are formulated in terms of linear matrix inequalities (LMIs). The results can be applied to a class of nonlinear systems that can be exactly represented by T-S fuzzy models inside a specific region called the region of validity. As a consequence, we need to provide an estimate of the set of safe initial conditions called the region of attraction such that the closed-loop trajectories starting in this set are assured to remain in the region of validity and to converge asymptotically to the origin. The estimate of the region of attraction is done with the aid of two sets: one dealing with the current state, and the other concerning the delayed states. Then, we can obtain the feedback fuzzy control law depending on the current state, xk, and the maximum delayed state vector, xk-d. It is shown that such a control law can locally stabilize the nonlinear discrete-time system at the origin. We also develop convex optimization procedures for the computation of the fuzzy control gains that maximize the estimates of the region of attraction. We present two examples to demonstrate the efficiency of the developed approach and to compare it with other approaches in the literature.

An Overview on Cardamonin

Luís Moreira Gonçalves,Inês Maria Valente,José António Rodrigues 한국식품영양과학회 2014 Journal of medicinal food Vol.17 No.6

Cardamonin, as shown by the increasing number of publications, has received growing attention from the scientific community due to the expectations toward its benefits to human health. In this study, research on cardamonin is reviewed, including its natural sources, health promoting aspects, and analytical methods for its determination. Therefore, this article hopes to aid current and future researchers on the search for reliable answers concerning cardamonin’s value in medicine.

BEM-FORM Model for the Probabilistic Response of Circular Tunnels in Elastic Media

Luís Philipe Ribeiro Almeida,Eduardo Toledo de Lima Junior,João Carlos Cordeiro Barbirato 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.7

Problems involving cavities or excavations are widely addressed in geomechanics, in both analytical and numerical approaches. The boundary element method (BEM) is well-known as an interesting choice for half plane problems, providing accurate results at a low computational cost. This work deals with the probabilistic analysis of circular tunnels embedded in elastic media, coupling a BEM formulation to a structural reliability model. The gravitational loading and material parameters are treated as random variables, whose statistical description is taken from the literature. The loadings considered include the vertical overburden stress and the lateral earth pressure. Regarding the reliability evaluation, first order reliability method (FORM) and Monte Carlo simulation technique are employed, being compared in terms of accuracy. Regarding the BEM model, the Multiple Reciprocity Method (MRM) is used in the evaluation of domain integrals, and the subregion technique is employed for the analysis of the tunnel lining. Some analyses are presented, in order to validate the coupled BEM-FORM model and apply it to the estimation of failure probability, evaluating the influence of the random variables taken into account in the probabilistic response.

Clinical comparison of intraoral CMOS and PSP detectors in terms of time efficiency, patient comfort, and subjective image quality

Kamburoğlu Kıvanç,Samunahmetoğlu Erçin,Eratam Nejlan,Sönmez Gül,Karahan Sevilay 대한영상치의학회 2022 Imaging Science in Dentistry Vol.52 No.1

Purpose: This study compared the effectiveness of complementary metal-oxide semiconductors (CMOS) and photostimulable phosphor (PSP) plates as intraoral imaging systems in terms of time efficacy, patient comfort, and subjective image quality assessment in real clinical settings. Materials and Methods: Fifty-eight patients (25 women and 33 men) were included. Patients were referred for a full-mouth radiological examination including 1 bitewing radiograph (left and right) and 8 periapical radiographs for each side (left maxilla/mandible and right maxilla/mandible). For each patient, 1 side of the dental arch was radiographed using a CMOS detector, whereas the other side was radiographed using a PSP detector, ensuring an equal number of left and right arches imaged by each detector. Clinical application time, comfort/pain, and subjective image quality were assessed for each detector. Continuous variables were summarized as mean±standard deviation. Differences between detectors were evaluated using repeated-measures analysis of variance. P<0.05 was accepted as significant. Results: The mean total time required for all imaging procedures with the CMOS detector was significantly lower than the mean total time required for imaging procedures with PSP (P<0.05). The overall mean patient comfort scores for the CMOS and PSP detectors were 4.57 and 4.48, respectively, without a statistically significant difference (P>0.05). The performance of both observers in subjectively assessing structures was significantly higher when using CMOS images than when using PSP images for all regions (P<0.05). Conclusion: The CMOS detector was found to be superior to the PSP detector in terms of clinical time efficacy and subjective image quality.