Search Results (53)

Countries that do not have oil and natural gas but are forced to reduce pollution due to combustion have stimulated and developed new technologies for absorption, storage, and energy creation based on nanotechnology. These new technologies are up-and-coming because they will solve the problem without additional environmental burden. The first technology is based on phase change materials (PCMs) that store the thermal energy produced by the sun and release it when requested. In the context of this article, there is a discussion about some devices that arise from this technology. The second technology is based on light nano-traps that convert solar energy into heat, which is then stored by heating water or other methods. The third practice is to absorb solar energy from nanoparticles, producing electricity. These technologies’ principles will be discussed and analyzed to understand their perspectives. Full article

We present two approaches for fabricating shadow masks for the evaporation of electrodes onto nanomaterials. In the first one, we combine the use of a commercial fiber laser engraving system with readily available aluminum foil. This method is suitable for fabricating shadow masks with line widths of 50 µm and minimum feature separation of 20 µm, and using it to create masks with complex patterns is very straightforward. In the second approach, we use a commercially available vinyl cutting machine to pattern a vinyl stencil mask, and we use a glass fiber to define the separation between the electrodes. With this approach, we achieve well-defined electrodes separated by 15 µm, but this technique is less versatile in creating complex masks as compared with the laser-based one. We demonstrate the potential of these techniques by fabricating field-effect transistor devices based on MoS₂. Our approach is a cost-effective and easily accessible method for fabricating shadow masks with high resolution and accuracy, making it accessible to a wider range of laboratories. Full article

The self-healing of cementitious materials can be achieved by precipitation of calcium carbonate through the enzymatic hydrolysis of urea. When a crack appears in cement, the damage can be repaired by allowing bacteria to encounter the water seeping through the crack. This forms a calcium carbonate, which heals the cracks. This occurs because microorganisms begin metabolizing and precipitating the mineral, healing the damage caused by the crack. Then, bacteria are incorporated into various containers, which release microorganisms by crushing, leading to the precipitation of calcium carbonate. In addition, this paper references the superabsorbent polymers (SAP) used for self-healing and hybrid organic-inorganic core–shell SAPs, a recently developed, state-of-the-art self-healing technology for cementitious materials. Full article

In this paper, three types of optical textured glass substrates were prepared at the glass/transparent conductive oxide interface using polydimethylsiloxane nanoimprint lithography to increase the conversion efficiency of dye-sensitized solar cells (DSSCs). There were three types of textures: nanotexture, microtexture, and micro/nano double texture. In terms of optical characteristics, it was confirmed that the reflectance of all of the textured glass substrates was lower than that of flat glass in the mean value of the 400–800 nm wavelength band. Further, the diffuse transmittance was higher than that of flat glass for all of the textured glass substrates, and the D-Tx was particularly high. DSSCs were fabricated using N749 and N719 dyes; their size was 6 mm². The conversion efficiencies of the N749 DSSCs were improved by 11% for the N-Tx (η of 2.41%) and 10% for the D-Tx (η of 2.38%) compared with flat glass (η of 2.17%) DSSCs. On the other hand, the M-Tx did not improve it. The conversion efficiencies of the N719 DSSCs with textured glass substrates were improved by 7.5% for the M-Tx (η of 2.74%), 18% for the N-Tx (η of 3.01%), and 26% for the D-Tx (η of 3.22%) compared with flat glass (η of 2.55%) DSSCs. Full article

High-temperature anneals of nonstoichiometric Si oxide (SiO_x, x < 2) films induce phase separation in them, with the formation of composite structures containing amorphous or crystalline Si nanoinclusions embedded in the Si oxide matrix. In this paper, a thermodynamic theory of the phase separation process in SiO_x films is proposed. The theory is based on the thermodynamic models addressing various aspects of this process which we previously developed. A review of these models is provided, including: (i) the derivation of the expressions for the Gibbs free energy of Si oxides and Si/Si oxide systems, (ii) the identification of the phase separation driving forces and counteracting mechanisms, and (iii) the crystallization behavior of amorphous Si nanoinclusions in the Si oxide matrix. A general description of the phase separation process is presented. A number of characteristic features of the nano-Si/Si oxide composites formed by SiO_x decomposition, such as the local separation of Si nanoinclusions surrounded by the Si oxide matrix; the dependence of the amount of separated Si and the equilibrium matrix composition on the initial Si oxide stoichiometry and annealing temperature; and the correlation of the presence of amorphous and crystalline Si nanoinclusions with the presence of SiO_x (x < 2) and SiO₂ phase, respectively, in the Si oxide matrix, are explained. Full article

Electrostatic charging of powders becomes important, when particles become smaller, especially for fine powders at micron or sub-micron size. Charging of powders causes strong particle adhesion and consequently difficulties in processes such as blending or mixing, and sieving, etc. Not only does the charge of powders influence the process and the quality of the products, but also the discharge creates risks of dust explosion. Assessing powder charge and the hazards in manufacturing can be difficult. One of the major challenges is to evaluate the charge levels and polarity in the powders but this requires a significant number of tests to detect charge tendency and distributions in bulk materials, which is time-consuming. In this paper, electrostatic charging of powders in material handling processes and the associated hazards are briefly reviewed. For an assessment, the challenges for sensing electrostatic charges of particulate solids, particularly for fine powders, are discussed. It was revealed that sensing the charge polarity for representative samples of powders can be the main challenge because of the difficulty in separation of the charged particles. The inductive charge sensor showed great potential to measure charge levels and polarity distributions in powders. Experimental trials for several fine powders showed that the inductive charge sensor can be used for rapidly assessing chargeability and charge polarity distribution of powders. Full article

The strong ferromagnetic nanoparticles are analyzed within the band structure-based shell model, accounting for discrete quantum levels of conducting electrons. As is demonstrated, such an approach allows for the description of the observed superparamagnetic features of these nanocrystals. Assemblies of such superparamagnets incorporated into nonmagnetic insulators, semiconductors, or metallic substrates are shown to display ferromagnetic coupling, resulting in a superferromagnetic ordering at sufficiently dense packing. Properties of such metamaterials are investigated by making use of the randomly jumping interacting moments model, accounting for quantum fluctuations induced by the discrete electronic levels and disorder. Employing the mean-field treatment for such superparamagnetic assemblies, we obtain the magnetic state equation, indicating conditions for an unstable behavior. Respectively, magnetic spinodal regions and critical points occur on the magnetic phase diagram of such ensembles. The respective magnetodynamics exhibit jerky behavior expressed as erratic stochastic jumps in magnetic induction curves. At critical points, magnetodynamics displays the features of self-organized criticality. Analyses of magnetic noise correlations are proposed as model-independent analytical tools employed in order to specify, quantify, and analyze the magnetic structure and origin of superferromagnetism. We discuss some results for a sensor-mode application of superferromagnetic reactivity associated with spatially local external fields, e.g., the detection of magnetic particles. The transport of electric charge carriers between superparamagnetic particles is considered tunneling and Landau-level state dynamics. The tunneling magnetoresistance is predicted to grow noticeably with decreasing nanomagnet size. The giant magnetoresistance is determined by the ratio of the respective times of flight and relaxation and can be significant at room temperature. Favorable designs for superferromagnetic systems with sensor implications are revealed. Full article

Silver nanoparticles (SNPs) can be produced by active and inactive forms of biomass, but their properties have not been compared. Recent research is attempting to reveal their differences in shape, size, amount, antibacterial activity, cytotoxicity, and apoptosis induction. The biomass of Fusarium oxysporum was divided into four groups and pretreated in the following devices: room temperature (RT) and refrigerator (for preparation of active biomass forms), autoclave, and hot air oven (for preparation of inactive biomass forms). Samples were floated in ddH₂O, and SNPs were produced after the addition of 0.1699 g/L AgNO₃ in the ddH₂O solution. SNP production was confirmed by visible spectrophotometry, transmission electron microscopy (TEM) and X-ray diffraction (XRD). SNPs were washed, and their concentration was determined by measuring atomic emission spectroscopy with inductively coupled plasma (ICP-OES). For antibacterial activity, the plate-well diffusion method was used. MTT and Annexin V-FITC/propidium iodide assays were used for cytotoxicity and apoptosis induction, respectively. The maximum absorbance peaks for SNPs pretreated in RT, refrigerator, autoclave, and hot air oven were 404, 402, 412, and 412 nm, respectively. The SNPs produced were almost the same shape and size, and the XRD results confirmed the presence of SNPs in all samples. Due to the differences in the type of bacterial strains used, the SNPs produced showed some differences in their antibacterial activity. The MTT assay showed that the amounts of SNPs in their IC₅₀ dose based on the results of ICP-OES were 0.40, 0.45, 0.66, and 0.44 ppm for the samples pretreated in the hot air oven, autoclave, and refrigerator, and RT, respectively. The apoptosis induction results showed that the biologically engineered SNPs induced more apoptosis (about 34.25%) and less necrosis (about 13.25%). In conclusion, the type and activity of SNPs produced by the active and inactive forms of fungal biomass did not change. Therefore, use of the inactive form of biomass in the future to avoid environmental contamination is reccommended. Full article

Mixed micelles from copolymers in aqueous media have emerged as a valuable tool for producing functional polymer nanostructures with applications in nanomedicine, including drug delivery and bioimaging. In this review, we discuss the basics of mixed copolymer micelles’ design, structure, and physicochemical properties. We also focus on their utilization in biomedical applications using examples from recent literature. Full article

Recently, several strategies have been adopted for the cesium lead halide, CsPbX₃ (X = Cl, Br, and/or I), crystal growth with a perovskite-type structure, paving the way for the further development of innovative optoelectronic and photovoltaic applications. The optoelectronic properties of advanced materials are controlled, in principle, by effects of morphology, particle size, structure, and composition, as well as imperfections in these parameters. Herein, we report a detailed investigation, using theoretical and experimental approaches to evaluate the structural, electronic, optical, and electrical properties of CsPbX₃ microcrystals. The microcrystals are synthesized successfully using the hydrothermal method without surfactants. This synthetic approach also offers an easy upscaling for perovskite-related material synthesis from low-cost precursors. Lastly, in this direction, we believe that deeper mechanistic studies, based on the synergy between theory and practice, can guide the discovery and development of new advanced materials with highly tailored properties for applications in optoelectronic devices, as well as other emergent technologies. Full article

Chloride–iodide perovskites have received substantial interest due to their better photovoltaic performance compared to pure iodide ones. The superior properties of chloride–iodide perovskites boost photovoltaic performance. However, quantifying the Cl composition in perovskite films remains challenging. Hence, it is not easy to correlate the Cl quantity with the improved photovoltaic performance. Considering this critical issue, it is still necessary to determine the correlation between the Cl quantity and the improved photovoltaic performance to solve this puzzle. Here, a critical review is presented showcasing the significant impacts of the Cl quantity on chloride–iodide perovskites and related solar cell devices. This review provides an up-to-date picture of different strategic methods to overcome the challenges of Cl incorporation in I-based perovskites, aiming to improve photovoltaic performance. Finally, some valuable remedies are prescribed for potential future research strategies to study the photovoltaic performance of chloride–iodide perovskite solar cells. Hopefully, this review will be a noteworthy scientific contribution to the advancement of the continuous progress of perovskite solar cells. Full article

It has been shown that defect-free Stone–Wales (SW) free few-layer graphene (FLG) can be obtained by carbonizing lignin under conditions of self-propagating high-temperature synthesis (SHS). The obtained few-layer graphene was used as a modifying additive for pyrotechnic compositions. It was found that the addition of 2.5 mass % of few-layer graphene synthesized from lignin to a pyrotechnic complex based on porous silicon and fluoropolymer leads to a significant increase in the combustion intensity of pyrotechnic compositions. Full article

The second most significant cause of cancer-related mortality and morbidity in the United States is colorectal cancer (CRC), the third most diagnosed malignancy. People over 50 have an increased risk of CRC everywhere in the world. Genetic and environmental risk factors significantly influence CRC development. Early detection is critical in the treatment and prevention of CRC. The population’s incidence rate of CRC is currently reduced by screening techniques and medicines, although recurrence of the disease may result from the cancer’s ability to spread locally. Consequently, the difficulty is in finding a different treatment for CRC. Nanotechnology is crucial for cancer treatment because it allows for the delivery of targeted chemotherapies to cancer cells directly and with greater therapeutic potency. Nanoemulsions have broad application in pharmaceutics, cosmetics, and food; their outstanding properties include enhanced dispersion of active hydrophobic components, small size, high surface area per unit volume, and improved absorption in cancer treatment. The present review highlights formulation aspects, preparation methods, and characterization techniques. We also provide a critical analysis of recent developments in nanoemulsions in colorectal cancer treatment that hold promise in delivering nanoemulsions in colorectal treatment. Full article