This study describes the production of nanocement (NC) using an efficient catalyst for the in-situ synthesis of Carbon Nanotubes (CNT) directly on Portland cement grains. The application of NC in mortar is straightforward and does not require the use of additives, surfactants, or any other agent to achieve homogeneous dispersion. The results show that incorporating 0.2% NC (1 g) to replace 10% of the Portland cement (39.5 g) in mortar not only reduces traditional cement usage and, consequently, the environmental impact by lowering CO2 emissions by approximately 20%, but also enhances mechanical properties, resulting in an increase of up to 33% in compressive strength. The research includes an in vitro biocompatibility assessment using MRC-5 cells, a normal human lung fibroblast cell line. The tests demonstrate that both CNT and mortar containing NC are highly biocompatible (over 90%). This makes NC a promising candidate for the safe application of CNT in cementitious matrices, while addressing environmental concerns. From both technological and innovative perspectives, NC represents a carbon-based alternative material with lower CO2 production and transportation costs compared to Portland cement, supporting its potential future classification as a green material.

This study reports the high-yield “in situ” growth of carbon nanotubes (CNT) on pozzolanic clay (P-Clay) and its application as a substitute for Portland cement in mortar. Initially, iron chloride hexahydrate (FeCl3·6H2O) and cobalt nitrate hexahydrate (Co(NO3)2·6H2O) supported on magnesium oxide (MgO) we used as catalysts, and the production of CNT over time was studied. The same catalyst was then employed for CNT synthesis on clay particles, resulting in an impressive 1700

Applications for carbon nanotubes (CNT) and the reuse of iron ore tailings (IOT) have been explored in the literature about nanostructured cementitious materials. Reinforced iron ore tailings (R-IOT) was produced growing CNT from an external catalyst directly on particles of IOT, regardless of its iron content. In this work, analyses by infrared spectroscopy detail the chemical bonds between IOT grains and the external catalyst. Also, different in situ CNT concentrations (0.05%, 0.2%, and 0.8%) in R-IOT were used for preparing a mortar which 25% of its aggregate's composition is reused IOT. R-IOT increased flexural strength (up to 29% with 0.8% CNT) and delivered better reinforcement efficiency (up to 60%) when compared to functionalized CNT. The electrical conductivity of the nanostructured composites was also higher (up to 370%) when compared nanostructured mortar to the mortar prepared from plain IOT. Contrary to the chemical CNT functionalization process to dispersion, the use of R-IOT to produce mortar is an easy and simple process that does not require additives, admixtures, surfactants, or any other additional chemical procedure. In terms of circular economy, the process combines innovation and sustainability since it reinserts IOT in the productive flow, representing an efficient application for this residue of mining activities.

A Olimpíada Brasileira de Astronomia e Astronáutica (OBA) teve sua primeira edição em 1998, promovendo, no Brasil, um evento educacional, com foco científico, já consolidado internacionalmente. O Grupo do Programa de Educação Tutorial de Conexões de Saberes em Física e Popularização da Ciência da Unifei (Campus Avançado de Itabira) criou um programa de atendimento e preparação de alunos com oficinas e gincanas de Astronomia. m parceria com um colégio de Ensino Fundamental de Itabira (MG). Baseado em uma metodologia que busca aliar o prazer em aprender com estudo constante dos alunos nos temas propostos, este programa visa solucionar as dificuldades no processo de formação dos alunos, na assimilação e construção de conhecimentos científicos e no processo de ensino-aprendizagem. Assim, diversas reações importantes foram observadas e este trabalho tem como objetivo mostrar análises relacionadas ao desempenho dos alunos do colégio na OBA. Foi verificado aumento de notas médias das turmas do 7º ao 9º ano, destacando-se as turmas do 7° ano com aumento de rendimento de 36%. Consequentemente, houve um aumento significativo no número de medalhas conquistadas, passando de 1 medalha para cada 50 alunos em 2015 para aproximadamente 1 medalha para cada 4 participantes em 2019.

This study reports the high-yield, “in-situ” growth of multi-walled carbon nanotubes on iron ore tailing. The final product is a pioneering approach on the use of nanostructured tailing to produce mortar with improved mechanical properties in a simple, effective methodology. Four different high-yield catalysts were developed to identify the most efficient parameters for the synthesis of carbon nanotubes (CNT) via Chemical Vapor Deposition on iron ore tailing (IOT). The process yields 1800% in carbon mass, an unprecedented result. Nanostructured IOT was used to produce mortar with different CNT quantities, including concentrations highly above the limits found in the literature, and resulted in increases of in flexural strength (up to 30%). Water loss after thermal treatment, consistency index and water absorption as a function of the CNT concentration in the mortar mass were also investigated. The proposed method delineates a viable way of incorporating CNT-reinforced macromaterials into cementitious matrices without functionalization, additives, or surfactants, which represents an advance for the nanocomposites industry. It also contributes to social and environmental development by aggregating value to iron ore tailing that would be otherwise stored in huge, and sometimes dangerous, disposal dams.

This study reports a new method of incorporating multi-walled carbon nanotubes (MWCNT) in mortar and the observed improvements in its mechanical properties. The method consists in growing carbon nanotubes (CNT) on sand grains prior to the mortar preparation instead of incorporating functionalized MWCNT (f-MWCNT) to the mixture. The use of additives or surfactants is not required. Flexural strength tests show an average increase of 12% in the strength when using f-MWCNT. Meanwhile, the average gain in flexural strength reached 26% with the proposed method. Also, image tests prove the efficiency of this new method in homogeneously distributing CNT bundles. Since no advanced technique is applied in producing mortar from the altered sand, the method represents a simple and economically viable way of incorporating CNT at building sites, disclosing a variety of future applications of nanotechnology in the cement industry.

Single-walled carbon nanotubes (SWCNT) are raising interest in biomedical field, as a drug delivery system, due to their large payload capacity and rich surface chemistry that allows attaching molecules. Generally, carbon nanotubes, without any surface modifications are cytotoxic to certain mammalian cells. However, after their functionalization, they become biocompatible and non-immunogenic. Thus, the aim of this work was to evaluate the effect of functionalization groups on the biocompatibility of SWCNT in vitro, as well as on its biodistribution in tumor-bearing mice. In this approach, carboxylate and bisphosphonate functionalized SWCNT were successfully synthesized and characterized by Raman, FTIR, and TGA techniques. The in vitro cytotoxicity against HEK-293 cells, and hemolysis assay were carried out and the results revealed important biocompatibility profile for both functionalized nanotubes. Furthermore, both types of SWCNT were successful radiolabeled with technetium-99 m, and biodistribution studies were conducted in Ehrlich tumor-bearing Swiss mice, showing higher tumor uptake by bisphosphonated SWCNT compared to carboxylated nanotubes. Moreover, acute toxicity study was performed in healthy Swiss mice revealing that none of the nanotubes displayed hematological, hepatic or renal toxicity. From all obtained results, the bisphosphonate functionalized SWCNT can be considered a plausible and alternative drug delivery platform for theranostic and therapeutics purposes.

The assessment of the biodegradability potential of carbon nanotubes (CNTs) is a fundamental point towards their applications in materials science and biomedicine. Due to the continuous concerns about the fate of such type of nanomaterials, it is very important to understand if they can undergo degradation under certain conditions and if the morphology and structure of the nanotubes play a role in this process. For this purpose we have decided to undertake a comparative study on the enzymatic degradation of CNTs with concentric multilayers. Double-walled (DW) and multi-walled (MW) CNTs of various lengths, degrees of oxidation and functionalizations using different methods were treated with horseradish peroxidase (HRP). While all tested DWCNTs resulted resistant to the biodegradation, some of the MWCNTs were partially degraded by the enzyme. We have found that short oxidized multi-walled CNTs functionalized by amidation were reduced in length and presented a high amount of defects at the end of the period of treatment with HRP. This comparative study holds its importance in the understanding of the structural changes of different types of nanotubes towards the catalytic enzymatic degradation and will help to design safer CNTs for future applications.

The infrared (IR) and Raman spectra of the osteoporosis drug alendronate in the monosodium trihydrate alendronate crystal were measured. In order to interpret them, density functional theory (DFT) calculations for the solvated alendronate molecule were performed following the structural features revealed by X‐ray data. A comparison between the DFT‐calculated IR and Raman of the converged species and the measured spectra unveils relevant phosphate group signatures in the 400–1400 cm−1 wavenumber range, especially IR absorption bands at 1015, 1049, 1067, 1131, 1177, and 1235 cm−1, which were related to CP and OP bond length stretching, and Raman lines at 449, 661, and 969 cm−1, involving phosphate scissors and bond length vibrations. A comparison with experimental data of alendronate incorporated into hydroxyapatite (HAP) indicates that, for wavenumbers below 1500 cm−1, the interaction of alendronate with HAP does not affect significantly the alendronate vibrational spectra, while for the 1600–3000 cm−1 interval the interaction with HAP changes the normal mode wavenumbers by about −100 cm−1. Copyright © 2014 John Wiley & Sons, Ltd.

OBJECTIVE:We evaluated the effects of sodium hyaluronate (HY) and carbon nanotubes functionalized with HY (HY-CNT) on bone repair in the tooth sockets of diabetic rats.MATERIALS AND METHODS:Diabetes was induced by streptozotocin (50 mg kg(-1) i.v.), and the sockets were divided into normal control, diabetic control, diabetic treated with HY (1%), and diabetic treated with HY-CNT (100 μg ml(-1)) groups. The sockets were analyzed according to the percentage of bone formation and the number of cell nuclei.RESULTS:The percentage of bone trabeculae was lower in diabetic control animals (11.16 ± 5.10% vs 41.92 ± 6.34% in normal animals) after 14 days. Treating diabetic animals with HY or HY-CNT significantly increased the percentage of neoformed trabeculae (HY: 29.43 ± 3.29%; HY-CNT: 36.90 ± 3.07%). Moreover, the sockets of diabetic animals had an increased number of cell nuclei and HY or HY-CNT reduced this parameter.CONCLUSION:Our results indicate that HY and HY-CNT restore bone repair in the tooth sockets of diabetic rats, suggesting that these biomaterials are potential adjuvant therapies for the management of diabetes.

Aims: Sodium hyaluronate (HY) accelerates the repair of bone defects. However, the weak stability of HY formulations in aqueous environments has hindered its wide utilization. The functionalization of carbon nanotubes (SWCNT) with NY (HY-SWCNT) results in a reinforced hydrogel with an increased stability. Nevertheless, the biological effects of HY-SWCNT have not been explored. Thus, our objective was to evaluate whether this biomaterial preserves the bioactivity of the HY.Main methods: Wistar rats were subjected to molar extraction and the sockets were treated with SWCNT (50-400 mu g/mL), 1% HY, HY-SWCNT (50-400 mu g/mL) or carbopol (vehicle). After seven days of surgery, histological and morphometric analyses were performed to evaluate the trabecular bone formation and the number of cell nuclei in the sockets. Expression of collagen types I and Ill was determined by immunohistochemistry.Key findings: Treatment with SWCNT did not alter the bone deposition, as well as the cell nuclei counting. Additionally, no significant evidence of toxicity was observed in SWCNT-treated sockets. Contrastingly, both HY and HY-SWCNT induced a marked increase in the bone formation (NY: 10.10 +/- 1.99%; HY-SWCNT 100 mu g/mL: 10.90 +/- 1.13%; control: 3.69 +/- 1.17%) and decreased the cell nuclei amount in the sockets. Moreover, collagen type I expression was more pronounced in HY- and HY-SWCNT-treated sockets. No significant differences were viewed in the expression of collagen type Ill.Significance: Our results indicate that SWCNT is a feasible material to deliver HY to bone defects. Importantly, the functionalization of SWCNT with HY preserved the beneficial biological properties of HY in the healing process, thereby suggesting that HY-SWCNT scaffolds are potentially useful biomaterials for the restoration of bone defects. (c) 2010 Elsevier Inc. All rights reserved.

Development of RNA interference (RNAi) technology utilizing short interfering RNA sequences (siRNA) has focused on creating methods for delivering siRNAs to cells and for enhancing siRNA stability in vitro and in vivo. Here, we describe a novel approach for siRNA cellular delivery using siRNA coiling into carboxyl-functionalized single-wall carbon nanotubes (SWCNTs). The CNT-siRNA delivery system successfully demonstrates nonspecific toxicity and transfection efficiency greater than 95%. This approach offers the potential for siRNA delivery into different types of cells, including hard-to-transfect cells, such as neuronal cells and cardiomyocytes. We also tested the CNT-siRNA system in a non-metastatic human hepatocellular carcinoma cell line (SKHep1). In all types of cells used in this work the CNT-siRNA delivery system showed high efficiency and apparent no side effects for various in vitro applications.

The field of bionanotechnology has been rapidly growing during the last few years and we can now envision a controllable integration between biological and artificial matter, where new biomimetic structures with a wide range of chemical and physical properties will promote the development of a novel generation of medical devices. In this work we describe a collagen/carbon nanotube composite which has the potential to be used as a scaffold for tissue regeneration. Because this biocomposite incorporates the advantageous properties of both collagen and carbon nanotubes, it has most of the characteristics that an ideal biomaterial requires in order to be used as an osteoinductive agent. This biocomposite is bioresorbable and biodegradable and has the desired mechanical rigidity while maintaining a three-dimensional(3-D) nanostructured surface. Tuned stability and swelling were achieved under fluid environments by varying the amount of carbon nanotubes (CNTs) incorporated into the composite. These variations can dictate the degree of interaction between fibroblastic cells and the biomaterials. Proof-of-concept was shown by performing an in vitro induced mineralization of hydroxylapatite crystals under physiological conditions. Furthermore, the ability to attach biofunctional groups to the CNT walls can open a new road for tissue regeneration since the combination of CNTs with specific growth factors or cellular ligands can create an environment capable of signaling and influencing specific cell functions. Our observations suggest that collagen/carbon nanotube biocomposites will have important uses in a wide range of biotechnological areas.

Amorphous silica nanowires have been produced by thermal annealing of Si/SiO2/Ni substrate structures at 900 degrees C under an atmosphere of hexamethyldisilazane (HMDS) and hydrogen (H-2). The wires have diameter ranging from 35 to 55 nm, which are controlled by the Ni particle size. It is demonstrated that the growth occurs through vapor-liquid-solid mechanisms, and it is proposed that the vapor source is volatile SiO generated from the etching of the Si substrate through active oxidation reactions. The role of the HMDS-H-2 atmosphere in promoting such reactions is discussed.

The synthesis and characterization of fluorescent microspheres of poly(2-methoxy,5-(2’ethyl-hexiloxy)-p-phenilene vinylene) MEH-PPV conjugated polymer encapsulated with polyvinyl alcohol (PVA) are presented. Comparison between the emission spectra obtained for MEH-PPV in chloroform solution and for a single PVA/MEH-PPV microsphere is done. The broadening and the enhancement of the vibronic peaks observed in the isolated microsphere spectrum are interpreted as due to confinement effects. Quality factors, of the order of 104 to 105, were estimated for microspheres radius ranging from 12 to 17μm, which strongly indicate that PVA/MEH-PPV microspheres are potential candidates for high gain spherical cavity lasers.