Visible Light Assisted Photocatalytic Degradation of Chromium (VI) by Using Nanoporous Fe2O3

A Fe2O3 nanoporous structure was prepared by using hydrothermal route; its physicochemical properties were effectively characterized using XRF, BET, FT-IR, VSM, SEM and EDX, DLS, XRD, and PL techniques. The surface area of the magnetic nanoporous structure Fe2O3 was higher than the normally synthesized Fe2O3 nanoparticle. The outcome of the photocatalytic removal of the chromium (VI) below the visible light irradiation confirmed that 82.11% of Cr(VI) was degraded by the Fe2O3 nanomaterials at 120 min of irradiation time. The improved photocatalytic activity of the nanoparticle was ascribed to efficient electron-hole separation. Fe2O3 was set up to be a tough and constant photocatalyst throughout recycling experiments. The conceivable mechanism for the electron-hole separation process on the heterojunction was probable. The synthesized samples own low band gap energy and a hollow structure appropriate for the improved photocatalytic activity. The toxicity of the samples was measured by using Mus musculus skin melanoma cells (B16-F10 (ATCC®, CRL-6475TM) which are set up to be safe for human cells; as a result, this systematic approach provides a better alternative upconversion material for integral photoabsorption.

Advances in Tendon and Ligament Tissue Engineering: Materials Perspective

Introduction. Tendons are specialised, heterogeneous connective tissues, which represent a significant healthcare challenge after injury. Primary surgical repair is the gold standard modality of care; however, it is highly dependent on the extent of injuries. Tissue engineering represents an alternative solution for good tissue integration and regeneration. In this review, we look at the advanced biomaterial composites employed to improve cellular growth while providing appropriate mechanical properties for tendon and ligament repair. Methodology. Comprehensive literature searches focused on advanced composite biomaterials for tendon and ligament tissue engineering. Studies were categorised depending on the application. Results. In the literature, a range of natural and/or synthetic materials have been combined to produce composite scaffolds tendon and ligament tissue engineering. In vitro and in vivo assessment demonstrate promising cellular integration with sufficient mechanical strength. The biological properties were improved with the addition of growth factors within the composite materials. Most in vivo studies were completed in small-scale animal models. Conclusions. Advanced composite materials represent a promising solution to the challenges associated with tendon and ligament tissue engineering. Nevertheless, these approaches still demonstrate limitations, including the necessity of larger-scale animal models to ease future clinical translation and comprehensive assessment of tissue response after implantation.

Molecular Dynamics Study on Deformation Mechanism of Grain Boundaries in Magnesium Crystal: Based on Coincidence Site Lattice Theory

As for magnesium (Mg) alloys, it has been noted that they are inferior to plastic deformation, but improvement in the mechanical properties by further refinement of grain size has been recently suggested. It means the importance of atomistic view of polycrystalline interface of Mg crystal. In this study, to discuss the deformation mechanism of polycrystalline Mg, atomistic grain boundary (GB) models by using coincidence site lattice (CSL) theory are constructed and are simulated for their relaxed and deformatted structures. First, GB structures in which the axis of rotation is in [11¯00] direction are relaxed at 10 Kelvin, and the GB energies are evaluated. Then, the deformation mechanism of each GB model under uniaxial tensile loading is observed by using the molecular dynamics (MD) method. The present MD simulations are based on embedded atom method (EAM) potential for Mg crystal. As a result, we were able to observe atomistically a variety of GB structures and to recognize significant difference in deformation mechanism between low-angle GBs and high-angle GBs. A close scrutiny is made on phenomena of dislocation emission processes peculiar to each atomistic local structure in high-angle GBs.

Reexamination of Solvothermal Synthesis of Layered Carbon Nitride

“Graphitic carbon nitride” synthesized by the solvothermal reaction between cyanuric chloride (C3N3Cl3) and sodium amide (NaNH2), which was one of the most common methods reported so far, was carefully examined by several analytical techniques for its chemical and structural characteristics. The chemical quantification by the electron microprobe and combustion methods showed that the product synthesized has a significant amount of hydrogen with a composition C3N5H3. Moreover, we found by FT-IR and IR-Raman measurements that the product consists mainly of stacked s-triazine units on the basis of the structural framework of cyanuric chloride, suggesting that s-triazine-based carbon nitride is more stable than heptazine-based one under a mild temperature condition (~200°C). The present study clearly demonstrates that hydrogen-free, pure graphitic C3N4 cannot be produced by the present solvothermal reaction proposed by the earlier study.

Modification of Aluminium 6063 Microstructure by Adding Boron and Titanium to Improve the Thermal Conductivity

This study aimed to improve the thermal conductivity of the Aluminium 6063 for heat sinks applications used in Central Processing Unit (CPU) of computers. Several studies had used different additional elements for this goal. In this paper, we studied the influence of Titanium and Boron addition on the thermal conductivity of Aluminium 6063. Several casting alloys samples were prepared with different percentage of addition elements and then heat-treated by homogenization and aging treatments. The results showed an important modification in thermal conductivity value per rapport to the reference metal, depending on the element of addition and its percentage. The bigger evolution was by using Boron in small percentage. More than 13% of the improvement was realized in the thermal conductivity with the addition of only 0.05% of Boron.

Well-Dispersed Nanoscale Zero-Valent Iron Supported in Macroporous Silica Foams: Synthesis, Characterization, and Performance in Cr(VI) Removal

Well-dispersed nanoscale zero-valent iron (NZVI) supported inside the pores of macroporous silica foams (MOSF) composites (Mx-NZVI) has been prepared as the Cr(VI) adsorbent by simply impregnating the MOSF matrix with ferric chloride, followed by the chemical reduction with NaHB4 in aqueous solution at ambient atmosphere. Through the support of MOSF, the reactivity and stability of NZVI are greatly improved. Transmission electron microscopy (TEM) results show that NZVI particles are spatially well-dispersed with a typical core-shell structure and supported inside MOSF matrix. The N2 adsorption-desorption isotherms demonstrate that the Mx-NZVI composites can maintain the macroporous structure of MOSF and exhibit a considerable high surface area (503 m2·g−1). X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD) measurements confirm the core-shell structure of iron nanoparticles composed of a metallic Fe0 core and an Fe(II)/Fe(III) species shell. Batch experiments reveal that the removal efficiency of Cr(VI) can reach 100% when the solution contains 15.0 mg·L−1 of Cr(VI) at room temperature. In addition, the solution pH and the composites dosage can affect the removal efficiency of Cr(VI). The Langmuir isotherm is applicable to describe the removal process. The kinetic studies demonstrate that the removal of Cr(VI) is consistent with pseudo-second-order kinetic model.

Investigation of Properties of Silk Fiber Produced in Ethiopia

The atmospheric conditions and other facilities to rear silk filaments are good in Ethiopia. In Awassa, Awash Melkassa, and Kombolcha silk rearing is started with good progress. The quality of the cocoons produced in the country is not determined in relation to commercial silk produced in major silk producing countries. So far there was no information available about the basic properties of silk filaments produced. In this research paper, the different physical properties of the eri and mulberry cocoon and their filaments were evaluated. Eri cocoons have shell ratio of approximately 14%, average fiber fineness of 3 dtex, and average weight of 3.2–3.3 g, while mulberry cocoons have raw silk ratio of 13-14%, average fiber fineness of 2 dtex, and average weight of 1.5 g. Even though the method of rearing, handling, and harvesting of the cocoons is poor, the physical properties of the silk produced in Ethiopia fall within the limits of commercial silk produced in major silk producing countries.

Utilizing Fullerenols as Surfactant for Carbon Nanotubes Dispersions Preparation

Dispersions of individual carbon nanotubes (CNTs) are crucial for nanodevices and polymer/CNTs nanocomposites. In this paper, stable and homogenous dispersions of individual multiwalled carbon nanotubes (MWCNTs) have been synthesized. The factors influencing the dispersibility mechanism, including the surfactant concentration and the pH value, have been investigated. SEM images display the impurities sticking on MWCNTs which have been removed. The oxygen-containing groups on the surface of MWCNTs sample have been detected through FT-IR and Raman spectra. All experimental results illustrate that using fullerenols as surfactant can greatly improve the dispersibility of MWCNTs. Moreover, the prepared dispersions exhibit good stability that the sediment percentage of fullerenols-MWCNTs is only 5.2% after 5 days.

Preparation, Characterization, and Cationic Functionalization of Cellulose-Based Aerogels for Wastewater Clarification

Aerogels are a series of materials with porous structure and light weight which can be applied to many industrial divisions as insulators, sensors, absorbents, and cushions. In this study, cellulose-based aerogels (aerocelluloses) were prepared from cellulosic material (microcrystalline cellulose) in sodium hydroxide/water solvent system followed by supercritical drying operation. The average specific surface area of aerocelluloses was 124 m2/g. The nitrogen gas (N2) adsorption/desorption isotherms revealed type H1 hysteresis loops for aerocelluloses, suggesting that aerocelluloses may possess a porous structure with cylindrically shaped pores open on both ends. FTIR and XRD analyses showed that the crystallinity of aerocelluloses was significantly decreased as compared to microcrystalline cellulose and that aerocelluloses exhibited a crystalline structure of cellulose II as compared to microcrystalline cellulose (cellulose I). To perform cationic functionalization, a cationic agent, (3-chloro-2-hydroxypropyl) trimethylammonium chloride, was used to introduce positively charged sites on aerocelluloses. The cationized aerocelluloses exhibited a strong ability to remove anionic dyes from wastewater. Highly porous and low cost aerocelluloses prepared in this study would be also promising as a fast absorbent for environmental pollutants.

Superplastic Grade Titanium Alloy: Comparative Evaluation of Mechanical Properties, Microstructure, and Fracture Behavior

In this investigation, static fracture, microstructure, and the mechanical behavior of SP-700 alloy (a superplastic grade) were evaluated and compared with two other titanium alloys. The comparisons were made in terms of suitably designed heat treatment cycles. The heat treatment cycles included annealing and a combination of solutionizing and aging treatments for all three alloys. Tensile properties were determined using MTS Landmark Servohydraulic Test System. Tensile tested samples’ fracture surfaces were investigated with LEO-VP SEM instrument. Ti-15-3-3-3 alloy exhibited relatively a higher combination of strength and ductility in comparison to the other two alloys. All three types of titanium alloys demonstrated a very good level of tensile strength and ductility suitable for applications in military and biomedical fields.