Applications of Metal and Metal Oxide-Based Nanomaterials in Medical and Biological Activities

Nanomaterials have been attracting the attention of many researchers because of their size, high stability, affinity, and selectivity nature. Over the past decades, considerable intensive studies on many metal and metal-oxide nanomaterials have drawn consideration through their significant properties like size, shape, surface mass proportion, and their reactivity; all these properties are fundamental cornerstones for the turn of events and use of nanomaterials and nanoscale gadgets in biomedical areas. There is also a vast scope for a broad range of biofunctional applications such as antibacterial, antiviral, antifungal, antitumor, bioimaging, tissue engineering, biosensors, gene, and drug delivery. The authors review the nature, forms, and synthesis of nanomaterials here, with a thorough biological synthesis assessment. They also address the development of nanoparticles by microorganisms in depth, and this chapter also includes updates on different biological and biomedical applications of these bionanomaterials.

Geopolymer Materials Based on Natural Pozzolans from the Moroccan Middle Atlas

The pozzolans of the Moroccan Middle Atlas are derived from a low explosive volcanism, mostly strombolian. They are mainly composed of olivine and pyroxene, presenting a less homogeneous structure (irregular vesicles). The main target of this project is to study the use of natural pozzolans (NP) and metakaolin as precursors for the production of geopolymeric binders. The characterization of raw materials and elaborated geopolymers was carried out to study their mineralogical, chemical, microstructural, and mechanical properties. The studied pozzolans and kaolin were crushed, grinded, and sifted to get a fine grain size diameter of less than 100 µm. Then, they were calcined at 750 °C for 2 h to achieve an amorphous structure, increasing of their reactivity. Geopolymer production consists of mixing pozzolans and metakaolin with different amounts with an alkaline solution of sodium hydroxide and sodium silicates. The mass proportion of metakaolin (MK) used in this study was 10%, 20%, and 30%. In the present work, the amount of metakaolin was added as a source of alumina. The elaborated geopolymers were characterized using XRD, FTIR, TGA, and SEM analyses. The compressive strength was measured at 7, 14, and 28 days. The results showed interesting mechanical proprieties at about 18 MPa at 28 days with the mixture containing 20% MK. The addition of MK showed a significant increase in mechanical properties of the elaborated geopolymer. Meanwhile, the other results confirmed the training of new phases in addition to N-A-S-H gel. All these results indicate that the use of pozzolans in the production of geopolymers could be a great solution for the sustainable management of this mineral resource.

Dynamic Behavior of Aviation Polymer Composites at Various Weight Fractions of Physical Modifier

The aim of this study was to determine the effect of a selected physical modifier with different granularity and mass percentage on the dynamics of aerospace polymer composites. The tests were carried out on samples made of certified aerospace materials used, among other purposes, for the manufacture of aircraft skin components. The hybrid composites were prepared from L285 resin, H286 hardener, GG 280T carbon fabric in twill 2/2 and alumina (Al2O3, designated as EA in this work). The manufactured composites contained alumina with grain sizes of F220, F240, F280, F320 and F360. The mass proportion of the modifier in the tested samples was 5% and 15%. The tested specimens, as cantilever beams fixed unilaterally, were subjected to kinematic excitation with defined parameters of amplitude and frequency excitation in the basic resonance zone of the structure. The results, obtained as dynamic responses, are presented in the form of amplitude–frequency characteristics. These relationships clearly indicate the variable nature of composite materials due to modifier density and grain size. The novelty of this study is the investigation of the influence of the alumina properties on system dynamics responses.

Resistance to the alkali-aggregate reaction of sustainable mortars produced with scheelite tailings in replacing natural sand aggregates

This work produced coating mortars with scheelite tailings (ST) in total replacement of natural sand aggregate. The chemical and mineralogical composition of the scheelite tailings was determined by X-ray diffraction (XRD) and X-ray fluorescence (XRF). Mortar samples with a mass proportion of 1:2:9 (cement: lime: sand/scheelite tailings) were prepared with and without the scheelite tailings. The mortars were evaluated by mercury intrusion porosimetry and compressive and flexural strength tests. The resistance to the alkali-aggregate reaction was assessed from the bar expansion test and by scanning electron microscopy (SEM) in the crack and pore regions. The results indicate that until the 22nd day, the scheelite tailings were not reactive; however, in 28 days, the expansion was deleterious. SEM images did not detect the presence of amorphous alkaline gel characteristic of the alkali-aggregate reaction. Therefore, although the mortar with scheelite tailings aggregate has shown the deleterious potential to 28 days, mechanical tests indicate that it has the potential to be used as a coating mortar.

Mercury Removal From Coal Combustion Flue Gas by Pyrite-Modified Fly Ash Adsorbent

Pyrite and fly ash have certain advantages in adsorption and mercury oxidation. The pyrite-modified fly ash (PY+AC-FA) mercury adsorbent was prepared by mixing pyrite (PY) with acid-modified fly ash (AC-FA), which has better mercury removal effect than AC-FA. The experimental results of mercury adsorption show: when the reaction temperature is 50°C, the best doping proportion of modified fly ash is 20wt%, the mass proportion of pyrite to acid modified fly ash is 4:1, and the flue gas flow rate is 1.0L/min, the adsorbent has the best performance, and the adsorption rate of mercury reaches 91.92%. BET, XRD, SEM, TG-DSG and XRF were used to characterize these adsorbents. And the mechanism of mercury removal of pyrite-modified fly ash adsorbent is inferred: Hg0 is first adsorbed on the surface of the adsorbent, and then oxidized to HgS by the active component FeS2 in pyrite-modified fly ash.

Development of Eco-Friendly Mortars Produced with Kaolin Processing Waste: Durability Behavior Viewpoint

This study presents the development of new eco-friendly mortar compositions containing kaolin residues (KR) and assesses their durability behavior. Firstly, the natural and calcinated kaolin residues (600 °C, 650 °C, 700 °C, 750 °C, and 800 °C) were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), granulometric analysis, and surface area. The kaolin residue calcinated at 800 °C was chosen to be added to new compositions of mortar because it presented the best pozzolanic performance. The aging tests accomplished in internal (Ei) and external (Ee) environments were applied in mortars with a mass proportion of 1:2:6 (cement + KR: lime: sand), in which the KR, calcinated at 800 °C, replaced the cement in the mass fraction of 0%, 5%, 10%, 15%, 20%, and 30%. The Ei was performed for 30, 60, 90, 180, and 360 days, and the Ee for 90; 210; 360; and 512 days. After the aging tests were completed, the mortar compositions containing KR were evaluated to determine their mineralogical phases (XRD), compressive strength (CS), and thermal behavior (DTA and thermogravimetry). In summary, the KR addition to the mortar compositions decreases the mechanical resistance to compression; however, mortars with a substitution of 10% and 20% presented resistance values within the minimum limit of 2.4 MPa established by ASTM C 270.

Efficiency of castor oil–based polyurethane foams for oil sorption S10 and S500: Influence of porous size and statistical analysis

This study evaluates the efficiency of castor oil–based polyurethane foams for oil sorption S10 and S500, focusing on the influence of the pores’ size. Different foams were produced by varying the polyol: isocyanate ratio (1:0.3; 1:0.5; 1:1.0; 1:1.5; and 1:2.0). The physicochemical properties, morphology, density, and Hg porosity were determined. The sorption capacity was influenced by exposure time, oil viscosity, and concentration of the reagents, considering variations in the hydrophobicity, void content, and morphology. The results showed that the foam produced at an in the same mass proportion (PUC) has a higher sorption capacity in exposure time from 25 to 40 h due to higher void content and larger pore diameter size. It was observed that the lower viscosity of S10 diesel contributes to the higher sorption efficiency compared to S500 one. The Taguchi method corroborated the mentioned results, indicating a higher sorption trend by varying the reagent concentration and exposure times.

Trends in forest fuel accumulation in pine forests of Kyiv Polissya in Ukraine

At present, forest fire research is becoming especially relevant in Ukraine. This study examines patterns of forest fuel accumulation in pine (Pinus sylvestris L.) stands that grow in different soil conditions with different pine stand structure. To estimate the load of forest fuel of different fractions, a combined methodology was used: the weighing method and the FIREMON (fuel load estimation) method. It was found that increase in surface forest fuel loads is not directly proportional to forest stands’ age. Fractional size distribution, capacity and loads of forest fuel depend on several factors, among which the greatest role is played by forestry characteristics of the pine stand. It was determined that in the forest site conditions of type C (fairly rich soils) in Kyiv Polissya, the share of forest litter compared to pine stands that grow in poor soil conditions (A) is smaller, ranging from 41% to 76% of the total forest fuel load. The mass proportion of the duff layer varies from 15% in young forest stands to 43% in mature stands. It was established that changes in forest fuel fractions for 1, 10, 100 and 1000 hours varied insignificantly with age rate. The share of substratum woody debris of 10 and 100 hours was insignificant and depended more on the forestry treatment regime on these sites. The mass proportion of coarse woody debris (1000 hours) was also insignificant, varying from 0% to 5.9% of the total load of surface fuel.