Sharif Digital Repository

Materials with medical applications must show different properties and requirements, such as mimicking bones' structures and supporting bone tissue formation (osteogenesis) for implants. Magnesium (Mg) alloys as biodegradable materials have recently become outstanding biomaterials because of their desirable properties like being soluble within the body, having low density, exhibiting near-to-natural-bone Young module, and having after-corrosion-based products, which are not only biologically degradable but also non-toxic. In addition to the mentioned properties, the ability to stimulate new bone growth and more outstanding biocompatibility of Mg alloys than other ceramic-based, polymeric,... 

Considering the quasi-brittle mechanical properties of concrete, wedge-splitting tests are employed and improved in this paper to study the fracture behaviour of concrete. A novel wedge-splitting device is designed by fixing ten springs on the force transmission component. The adaptive spring force can be imposed on top of a concrete specimen to retard the brittle fracture process. With the proposed wedge-splitting test design for notched cuboid specimens, the complete load–strain/CMOD curves of concrete can be generated directly. The fracture toughness and the fracture energy can be calculated easily without numerical fitting using the double-K fracture model. The descending branch of the... 

A new method for the simulation of crack initiation and propagation in quasi-brittle materials is proposed that combines the scaled boundary finite element method and a nonlocal multiscale damage model. The scaling centre of the scaled boundary finite element subdomain is taken as the material point. Microscopic damage is defined in terms of the stretch rate of bonds of material points, and macroscale topologic damage is evaluated as the weighted average of microscale damage over bonds in the influence domain. Through the energetic degradation function of phase field analysis, which connects energy-based damage and macroscale topologic damage, the nonlocal multiscale damage model is inserted... 

This research analyzes a laminated double-curved panel's free/forced vibrational features and Low-Velocity Impact (LVI) Accordingly, the Hertz contact scheme is introduced to model the contact force between the structure and the impactor. Additionally, Hamilton's principle and four-variable refined quasi-3D logarithmic shear deformation theory (RQ-3DLSDT) are accessible for figuring out a structure's motion and Boundary Condition (BC) equations for the LVI. Moreover, for computing the motion equation in the displacement and time frames, respectively, the Galerkin and Newmark methods are provided. Finally, there are two subsections within the results section. The first examines the influence... 

The compressive performance of glass fiber reinforced polymer (GFRP) profiles subjected to elevated temperature was investigated through a large number of (3 0 0) tests. The effects of profile cross-sectional area, slenderness, and temperature on the behavior of the GFRP profiles at temperatures ranging from 25 to 400 °C were determined. It was observed that the compressive strength of the GFRP profiles has been decreased by half as the temperature exceeded 90 °C, i.e., close to the glass transition temperature of the matrix. The temperature and ratio of cross-sectional area to external perimeter were determined as two major parameters affecting section capacity. © 2020 Elsevier Ltd  

A very simple and well-controlled procedure was employed to prepare CdS nanoparticle/few-layer MoS2 nanosheet/Indium tin oxide (ITO) thin film heterostructures. To tune and fabricate the CdS/MoS2(t)/ITO thin films with various surface topographies, first electrophoretic deposition (EPD) was used to deposit MoS2 nanosheets on the ITO substrate under an optimized applied potential difference (8 V) for different deposition times (t) of 30, 60, 120 and 240 s. Then, CdS nanoparticles were deposited via a successive ion layer adsorption and reaction (SILAR) technique. The highest photo-current density of 285 μA cm-2 was measured for the CdS/MoS2(60 s)/ITO sample, which was about 2.3 times higher... 

Plasma medicine, or the biomedical application of cold atmospheric plasma (CAP), is an expanding field within plasma research. CAP has demonstrated remarkable versatility in diverse biological applications, including cancer treatment, wound healing, microorganism inactivation, and skin disease therapy. However, the precise mechanisms underlying the effects of CAP remain incompletely understood. The therapeutic effects of CAP are largely attributed to the generation of reactive oxygen and nitrogen species (RONS), which play a crucial role in the biological responses induced by CAP. Specifically, RONS produced during CAP treatment have the ability to chemically modify cell membranes and... 

In this manuscript, the sequel of agglomeration on the vibration of fiber metal laminated (FML) cylindrical shell in the micro phase using developed couple stress theory (MCST). Hamilton's principle has been carried out for deriving the non-classical equations of motion of size-dependent thin micro cylindrical shell on the basis of Love's first approximation theory. Mori-Tanaka and extended rule of mixture are utilized to estimate the mechanical attributes of carbon nanotubes (CNTs) and equivalent fiber, respectively. These four phases CNTs/fiber/polymer/metal laminated (CNTFPML) micro cylindrical shell is analyzed applying beam modal function model for several boundary limitations. Then, an... 

Retained austenite as a key constituent in final microstructure plays an important role in TRansformation Induced Plasticity (TRIP) steels. The volume fraction, carbon concentration, size, and morphology of this phase are the well-known parameters which effects on the rate of transformation of retained austenite to martensite and the properties of steel, are studied by many researchers. Of the transformation of retained austenite to martensite under strain in a TRIP steel is studied in this paper. The experimental results show that the transformation rate of retained, austenite with similar characteristics, to martensite in differently processed TRIP steel samples, exhibits an anisotropic... 

This study was aimed at gaining an improved understanding of the behavior of glass fiber-reinforced polymer laminates at elevated temperatures by means of testing laminate specimens with unidirectional, woven, and randomly distributed (chopped strand mat) fibers. The testing parameters were temperature, the type of fiber, and the thickness of the laminates. The failure modes of the specimens and their elasticity moduli at ambient temperature were investigated, and analysis of variance was conducted to determine the contribution of each parameter to the behavioral test results. The findings showed that among the parameters, an increase in temperature exerted the strongest effect on the... 

Direct solvent exfoliation of bulk MoS2 with the assistance of poly(3-hexylthiophene) (P3HT) produces a novel two-dimensional organic/inorganic semiconductor hetero-junction. The obtained P3HT-MoS2 nanohybrid exhibits unexpected optical limiting properties in contrast to the saturated absorption behavior of both P3HT and MoS2, showing potential in future photoelectric applications  

In this research, we developed a cost-effective automated guided vehicle for small clothing production workshops that ordinary workers in such workplaces can operate. We acquired workers’ opinions in multiple workshops about using the robots (with some social capabilities) and working alongside them. We performed the tests in China and Iran to investigate and compare different preferences and priorities in two countries with different cultural backgrounds. We used the UTAUT questionnaire and conducted two-way ANOVA tests considering two independent factors: Nationality and Gender. The results showed that workers in Iran and China have relatively similar expectations from a social AGV, with... 

This study investigates the flexural and impact behaviour of GFRP laminates after exposure to elevated temperatures. The effect of fibre's length and orientation, laminate's thickness, and exposure time is studied. A total number of 540 tests in terms of three-point bending and Charpy impact tests were conducted to obtain the mechanical properties. In addition, SEM analyses were carried out to investigate the degradation mechanisms. Finally, statistical study was conducted to investigate the contribution of each variable and develop probabilistic models using ANOVA and linear Bayesian regression method. The results showed that generally the flexural and impact properties of GFRP laminates... 

The huge volume change and unstable interface of the silicon anode usually result in the fracture of the active material and the disconnection with conducting agent/current collector, which would highly hinder the application of silicon in powering battery. Moreover, the un-uniform charge distribution at the surfaces of silicon would cause a degration of capacity at fast charging condition or low temperature. Thus, developing a stable interface with good mechanical stability to tolerate huge volume change of the silicon, and keep the robust adhesive property is one of the effective methods of resolving the above questions but a great challenge. Here, a molecular zipper fastened strategy is... 

The present research examines the effects of UV radiation, moisture and elevated temperature on the mechanical properties of GFRP pultruded profiles. Flexural, compressive and tensile properties of different GFRP sections were studied after they were exposed for 1000, 1500, 2000 and 3000 h to UV radiation and water vapour condensation cycles. Mechanical tests, including three-point bending, compression and tension tests, SEM analyses, and statistical studies were conducted to gather comprehensive results. The results showed that the mechanical properties of various GFRP sections generally decreased with the duration of conditioning: however, the rate of the decrease that was only slight up... 

MXene-based gas-sensitive nanocomposites are an area of high interest in developing high-performance gas sensors that operate at room temperature. Combining MXene with different nano-sized metal oxides is a strategy to improve sensing performance, but poor chemical stability, especially in humid environments, is the biggest obstacle to practical applications. Recently we demonstrated a method to prepare a ternary heterostructure gas sensor by decorating a stable TiO2/Ti3C2Tx composite with MoO3 which also provided selectivity. Here, we develop the proposed concept by synthesizing a Cr2O3/TiO2/Ti3C2Tx gas-sensitive material that shows a unique rapid and selective response to Triethylamine. In... 

Microorganisms have been essential in the natural world for millions of years, contributing significantly to environmental interaction. It has been disoverd that some bacteria are potential in geotechnical and environmental engineering due to their outstanding ability of biomineralization. Therefore, how to train bacteria as special and professional “workers” for biomineralization is increasingly a key topic in related research fields. This article briefly introduces the methods that are commonly utilized to improve the environmental adaptability and mineralization efficiency of bacteria, including microbial domestication, microbial mutation breeding, microbial targeted screening, and... 

Relations between the US and China have deteriorated to their lowest point since their rapprochement in the 1970s. To make sense of contemporary geopolitics, our objective in this article is two-fold. First, we historically situate contemporary US-China rivalry to conceptualise the Second Cold War (SCW). We argue that in the wake of the 2008 financial crisis, both the US and China launched ‘restorative’ political projects that harked back to imagined pasts. These projects are mutually exclusive and animate contemporary geopolitics. Second, we conceptualise the spatial logic of great power rivalry in the Second Cold War. In contrast to the first Cold War, when great powers sought to... 

A recently developed two-level undercut-profile substrate (2LUPS), containing two levels of plateaus connected by a curved wall with an undercut profile, enables self-forming filaments in a coated conductor during physical line-of-sight deposition of buffer and superconducting layers. In the present study, the 2LUPS concept is applied to a commercial cube-textured Ni-5at.%W tape, and the surface of the 2LUPS coated with two Gd2Zr2O7 buffer layers using chemical solution deposition is examined. Except for narrow regions near the edge of upper plateaus, the plateaus are found to be covered by strongly textured Gd2Zr2O7 buffer layers after dip coating and sintering  

Background: Planarians are non-parasitic Platyhelminthes (flatworms) famous for their regeneration ability and for having a well-organized brain. Dugesia japonica is a typical planarian species that is widely distributed in the East Asia. Extensive cellular and molecular experimental methods have been developed to identify the functions of thousands of genes in this species, making this planarian a good experimental model for regeneration biology and neurobiology. However, no genome-level information is available for D. japonica, and few gene regulatory networks have been identified thus far. Results: To obtain whole-genome information on this species and to study its gene regulatory...