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In the present research, the structural, electronic and optical properties of transition metal dichalcogenide-doped transition metal oxides MoS2-doped-V2O5 with various doping concentrations (x = 1–3%) of MoS2 atoms are studied by using first principles calculation. The generalized gradient approximation Perdew–Burke–Ernzerhof simulation approach is used to investigate the energy bandgap (Eg) of orthorhombic structures. We examined the energy bandgap (Eg) decrement from 2.76 to 1.30 eV with various doping (x = 1–3%) of molybdenum disulfide (MoS2) atoms. The bandgap nature shows that the material is a well-known direct bandgap semiconductor. MoS2 doping (x = 1–3%) atoms in pentoxide (V2O5) creates the extra gamma active states which contribute to the formation of conduction and valance bands. MoS2-doped-V2O5 composite is a proficient photocatalyst, has a large surface area for absorption of light, decreases the electron-hole pairs recombination rate and increases the charge transport. A comprehensive study of optical conductivity reveals that strong peaks of MoS2-doped-V2O5 increase in ultraviolet spectrum region with small shifts at larger energy bands through increment doping x = 1–3% atoms of MoS2. A significant decrement was found in the reflectivity due to the decrement in the bandgap with doping. The optical properties significantly increased by the decrement of bandgap (Eg). Two-dimensional MoS2-doped-V2O5 composite has high energy absorption, optical conductivity and refractive index, and is an appropriate material for photocatalytic applications.

Dense thin films of TiO2 and TiO2 doped with Zr4+ were spin coated on glass substrate and annealed at 450 °C. The optical characteristics and crystalline structure were studied using UV–vis, PL, XRD, and SEM. X-ray investigation proved that an anatase phase was formed in all Zr-doped samples (0, 0.5, 1, 5, and 10 %). Zr-doping changes the band gap energy from Eg = 3.48 eV (undoped) to 3.57 eV (1 % doping), along with the large size of Zr4+ results in slight lattice enlargement. Increasing Zr-doping beyond 1.0 % is associated with decreasing the band gap due to amorphization of TiO2. The anatase crystallites growth is stalled with increasing doping; from 23.5 nm to 10.43 nm and micro-strain increases with increasing doping concentration. The changes in optical properties, crystal growth and structure properties are due to lattice strain created by the collective effect of Zr-doping and reduction in crystallite size. Zr-doped TiO2 nanoparticles exhibited typical photoluminescence (PL) matching to the visible spectrum region when excited at 275 nm. The produced thin films had a lower rate of electron–hole recombination than TiO2 that was not doped.

One of the key issues involved in successfully achieving hydroxyapatite (HA) ceramic body without defects using colloidal processing technique, is the preparation of homogeneously high solid loading HA ceramic suspension. This could be achieved via controlling the HA powder properties. The maximum achievable solid loading suspension from the as received HA powder was found to be 14 vol%. The treatment of the as received powder via heat treatment process play a very versatile role in changing the physical properties of the powder. Owing to these changes, well dispersed high solid loading HA suspensions reaching 57 and 59 vol% were successfully prepared from HA powder heat-treated at 1000 and 1100 °C, respectively. The suspensions prepared from the heat-treated powder was found to have acceptable rheological properties for casting processes in terms of low particle interaction, lower number of floc and floc network and higher fluidity.

Recently, a considerable research effort has been devoted to bridge design and evaluation in Egypt. The traffic loading in the Egyptian code (ECP) gets heavier from 1963 to 2012. So, it was necessary to evaluate how much safe are the existing bridges when loaded with heavier traffic loading. For this reason, a comparative study is presented between the internal forces (bending moments) in longitudinal girders and deck slabs, in slab/girder bridges, resulting from traffic loads recommended by ECP 1963, ECP 1994 and ECP 2012. Tables and figures are displayed to show the variation in live load moments when using the three different codes for bridges with 10.5 m width (three traffic lanes) and with spans 15, 20 and 25 m. Since most highway bridges are continuous ones, the present analysis was expanded to cover the effects of the different recommended live loads on continuous bridges. The results reveal big differences between the different versions of traffic loads in the Egyptian codes. In addition, modified equations to calculate maximum moments in longitudinal girders according to ECP2012 are proposed. The proposed equations show excellent results when compared with the numerical study. Keywords: Traffic loads, Reinforced concrete bridges, Slab/girder bridges, Egyptian code ECP201

Preservation of environment and natural resources has recently attracted researchers to study the use of recycled aggregates from demolished concrete in new concrete structures. This paper presents an experimental study on punching shear behavior of simply supported natural and recycled coarse aggregate concrete slabs. The punching shear behavior of interior slab–column connection in flat plates is tested in “The Reinforced Concrete Laboratory of the Faculty of Engineering, Alexandria University”. Eight two-way slab specimens using two different types of aggregate “natural and recycled” and two aggregate nominal sizes (12.5 and 25 mm) were cast and tested to failure. The slabs were designed such that they would fail in punching shear only. The experimental work was conducted on (6) recycled coarse aggregate concrete (RCAC) slab specimens and (2) natural coarse aggregate concrete (NCAC) slabs. All the slabs were simply supported on four edges and tested under a central patch load. The ACI mix design procedure was adopted to achieve strength of concrete at 28 days of 35 MPa. Four concrete mix proportions were used with (0%, 30%, 60% and 100%) replacement of natural coarse aggregate with recycled coarse aggregate for each aggregate size. The test results showed that the first punch crack load, ultimate punch load, stiffness and energy absorption decrease as the replacement of natural coarse aggregate with recycled coarse aggregate increases. Also as the recycled aggregate size increases the cracking and failure load increases. The measured ultimate failure loads have been compared with code predictions (ECP 203, ACI 318, JSCE code, Euro code 2 and yield line theory). The Euro code – 2 equations gave the best correlation with the experimental results. Keywords: Punching shear, Two-way slab, Recycled coarse aggregate (RCA), Natural coarse aggregates (NCAs), Coarse aggregate sizes

Superstructure loads are transmitted to the underlying soil strata through a suitably designed foundation. Therefore, the foundation of a structure is considered the most crucial structural element in a building. The foundation may be classified into two main categories, shallow and deep foundations. Shallow foundation comprises isolated column footings, combined footings and reinforced concrete mat. The design of isolated column footing is accomplished through the application of geotechnical and structural analysis concepts. So that, the input research into isolated column footings comes from two different disciplines, geotechnical and structural. This may be one of the main causes that attributed to the limited research input to the subject. Therefore, the structural design of isolated column footings is based on empirical rules and the calculations of bending moments (BM) and shearing forces (SF) induced in a footing are based on the rules of beam theory, which is questionable. On the other hand, punching theory was developed on relatively thin floor slab, even though the theory is implemented for the calculation of punching shear in relatively thick footings. Also experimental research on isolated column footings is scarce, due to the difficulties involved in the setup of the laboratory models and the cost of experiments. The work presented in this article deals with the correlation between failure loads predicted by different code provisions, ECP203-11, ACI318-08, BS 8110.1-1997 and EC2-2004, of isolated column footings, and the corresponding measured values. The study showed that shear span to depth ratio of a footing and distributions of contact stress at footing–soil interface are key factors in the structural design of the footing. ECP203-11, ACI318-08, and EC2-2004 code provisions, underestimate the structural failure loads of isolated column footings, while BS 8110.1-1997 overpredicts the failure loads of isolated column footings, if punching provisions at perimeter of column are pulled out from the code.

This paper presents an experimental investigation on the behavior and strength of reinforced concrete slabs with lap splice of tension reinforcement using headed bars. Nine simply supported reinforced concrete one-way slabs were tested to study the effect of lap splices length, confinement at the splice zone, debonding of bars in the splice zone, and applying repeated gradually increasing cyclic loading. It was concluded that implementation of lap splice length as stated by ACI 318-14 for headed bars, but without adding confinement in the splice zone, and using cut-off ratio equal to 100%, led to brittle failure of the slab and the ductility was reduced. When the tested slabs were provided with confinement in the splice zone, the strength of slabs was improved and ductility of these slabs was remarkably increased. Additionally, the integrity of the lap joint was preserved when subjected to repeated gradually increasing cyclic loading.

Visible light active, highly stable, nontoxic, and efficient photocatalysts based on 1 %, 3 %, and 5 % Mn@Co3O4 were synthesized and functionalized with reduced graphene oxide. The X-rays diffraction (XRD) spectroscopy and FT-IR spectroscopy were employed for structural and functional group studies. Under visible light irradiation, photocatalytic activities of 1 %, 3 %, and 5 % Mn@Co3O4/rGO nanocomposites were studied for the degradation of organic pollutant methylene blue. Almost 85.4 %, 90.2 %, and 93.4 % degradation of methylene blue were observed after 80 min with 1 % Mn@Co3O4/rGO, 3 % Mn@Co3O4/rGO, and 5 % Mn@Co3O4/rGO respectively. The prepared nanocomposites followed pseudo-first-order kinetic studies. Among all samples, the 5 % Mn@Co3O4/rGO showed maximum degradation of 93.4 % in 80 min. Moreover, 5 % Mn@Co3O4/rGO nanocomposite maintained its excellent dye degradation ability even after three cycles. [ABSTRACT FROM AUTHOR]

Industrialization and urbanization have now become major factors in damaging different segments of the environment. Synthesis of novel nanomaterials for the removal of dyes and free radicals from aqueous medium has become a challenge for the researchers. The present work describes formation of novel-franklinite (ZnFe2O4) nanoparticles (FNPs) which have been synthesized adopting economical route of green method using extracts of fresh and dried leaves of Coriandrum sativum. The fabricated NPs were characterized employing state of the art analytical techniques including UV-visible, FTIR, SEM and XRD. The nanocatalyst exhibited excellent catalytic properties for the degradation of eosin yellow up to 86 % in 22 min and 90 % in 16 min using zinc-ferrite NPs synthesized using dried and fresh leaves respectively. Antioxidant activity of ZnFe2O4 in terms of DPPH and ABTS free radicals scavenging was also determined. Nanoparticles synthesized using fresh leaves exhibited better antiradical potential in comparison to NPs synthesized dried leaves. Therefore, synthesis of FNPs with active features can be achieved using extract of fresh plant. Franklinite NPs can be used as promising photocatalyst for the degradation of organic pollutants and scavenging of free radicals. [ABSTRACT FROM AUTHOR]