Including Iron Oxide Research Articles

Iron-Based Theranostic Nanoplatform for Improving Chemodynamic Therapy of Cancer.

Chemodynamic therapy (CDT) has aroused extensive attention for cancer treatment in the last five years, as it could suppress tumor progression through in situ detrimental oxidative stress of the tumor cells via the Fenton reaction. Under a tumor acidic microenvironment, the Fenton reaction can be initiated for disproportioning endogenous hydrogen peroxide into highly toxic hydroxyl radical. Taking advantage of the highly tumor-specific therapy modality, various Fenton nanocatalysts have been developed for CDT. In particular, iron-containing Fenton nanocatalysts with minimal cytotoxicity exhibit great promise for clinical translation. In this review, we summarize the recent progress of CDT based on iron-containing nanomaterials, including iron oxide nanoparticles, glassy iron nanoclusters, ferrocene nanoparticles, metal polyphenol networks, metal-organic frameworks, etc. We also discuss the challenges and perspectives for promoting CDT by rational design of iron-containing nanomaterials, highlighting their potential for precise cancer therapy.

Automated detection of corrosion in used nuclear fuel dry storage canisters using residual neural networks

Nondestructive evaluation methods play an important role in ensuring component integrity and safety in many industries. Operator fatigue can play a critical role in the reliability of such methods. This is important for inspecting high value assets or assets with a high consequence of failure, such as aerospace and nuclear components. Recent advances in convolution neural networks can support and automate these inspection efforts. This paper proposes using residual neural networks (ResNets) for real-time detection of corrosion, including iron oxide discoloration, pitting and stress corrosion cracking, in dry storage stainless steel canisters housing used nuclear fuel. The proposed approach crops nuclear canister images into smaller tiles, trains a ResNet on these tiles, and classifies images as corroded or intact using the per-image count of tiles predicted as corroded by the ResNet. The results demonstrate that such a deep learning approach allows to detect the locus of corrosion via smaller tiles, and at the same time to infer with high accuracy whether an image comes from a corroded canister. Thereby, the proposed approach holds promise to automate and speed up nuclear fuel canister inspections, to minimize inspection costs, and to partially replace human-conducted onsite inspections, thus reducing radiation doses to personnel.

Magnetic contributions in multiferroic gadolinium modified bismuth ferrite ceramics

Bi0.88Gd0.12FeO3 multiferroics are of interest for next-generation electronics and are shown with a remnant magnetization 0.2 emu·g−1, coercive field 8 kOe, Curie temperature 370 °C and magnetization of 0.7 emu·g−1 at magnetic fields 30 kOe. Scanning probe microscopy confirmed the intrinsic multiferroicity in the perovskite phase with coexistence of ferroelectric/ferroelastic and ferromagnetic domain structures. Strong magnetic hysteresis was produced by thermal cycling to 1000 °C due to degeneration of the perovskite phase into iron oxide inclusions, highlighting the importance of processing, thermal history and thermodynamic stability for minimizing the amount of parasitic magnetic secondary phases.

Synergistic photocatalytic effect between green LED light and Fe3O4/ZnO-modified natural pumice: A novel cleaner product for degradation of methylene blue

Herein, an efficient photocatalytic system is prepared and applied for photocatalytic degradation of methylene blue (MB), under green light irradiation. This catalytic system is made of the nanosized ingredients including iron oxide nanoparticles (Fe3O4 NPs) and zinc oxide nano-rods (ZnO NRs), to provide a wide surface active area. The first and foremost point from the structural aspect is the magnetic property enhancement through well composition of the natural pumice micro-plates with Fe3O4 NPs, as two magnetic ingredients. Through this property, the catalyst’s particles are conveniently collected and reused for additional eight times. Concisely, the highest photocatalytic efficiency (85.5%) has been obtained through using 50?mg of ZnO/Fe3O4@pumice photocatalyst under green LED light (7?W, 526?nm) irradiation, for 60?min. In this study, a plausible photocatalytic mechanism for degradation of the MB by the produced photocatalytic system is suggested as well.

Technetium immobilization by materials through sorption and redox-driven processes: A literature review.

The objective of this review is to evaluate materials for use as a barrier or other deployed technology to treat technetium-99 (Tc) in the subsurface. To achieve this, Tc interactions with different materials are considered within the context of remediation strategies. Several naturally occurring materials are considered for Tc immobilization, including iron oxides and low solubility sulfide phases. Synthetic materials are also considered, and include tin-based materials, sorbents (resins, activated carbon, modified clays), layered double hydroxides, metal organic frameworks, cationic polymeric networks and aerogels. All of the materials were evaluated for their potential in-situ and ex-situ performance with respect to long-term Tc uptake and immobilization, environmental impacts and deployability. Other factors such as the technology maturity, cost and availability were also considered. Given the difficulty of evaluating materials under different experimental conditions (e.g., solution chemistry, redox conditions, solution to solid ratio, Tc concentration etc.), a subset of these materials will be selected, on the basis of this review, for subsequent standardized batch loading tests.

Application of decorated magnetic nanophotocatalysts for efficient photodegradation of organic dye: A comparison study on photocatalytic activity of magnetic zinc sulfide and graphene quantum dots

In the present research, two magnetic nanophotocatalysts (MNPCs) including iron oxide nanoparticles decorated with zinc sulfide quantum dots (Fe3O4@ZnS QDs), and N,S- doped graphene QDs (Fe3O4 @ N, S-GQDs) were synthesized by the sonochemical and hydrothermal methods, respectively. The prepared MNPCs were characterized by various techniques including X-Ray Diffraction (XRD), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM), UV–vis absorption and Fourier transform infrared (FT-IR) spectroscopy. The SEM images show the formation of nano- sized particles of Fe3O4, also the morphology and size of the particles were changed after their decoration with ZnS and GQDs. The magnetic saturation values of Fe3O4@ZnS QDs and Fe3O4 @ N, S-GQDs samples were obtained as 19.43 and 55.58 emu.g−1, respectively. The desirable paramagnetic properties of the samples provide suitable magnetic separation process and simple recyclyig of MNPCs. The photocatalytic activity of the as-synthesized samples was evaluated through investigating their ability to degrade an organic pollutant (i.e. Victoria Blue R dye) in aqueous media. The photodegradation efficiency was evaluated based on the decrease of VBR concentration at its maximum absorption wavelength, in the presence of Fe3O4@ZnS QDs and Fe3O4 @ N, S-GQDs as nanophotocatalyst and under ultraviolet (UV) and visible (Vis) light irradiations, respectively. In optimization experiments, the effect of various factors including pH, dye concentration, irradiation time, MNPC dosage, type and concentration of salts were investigated. The maximum photodegradation percentage of Fe3O4@ZnS QDs was obtained as 93.44 % at pH 8, and in the case of Fe3O4 @ N, S-GQDs as 96.68 % at pH 9, after 120 min irradiation.

Discovery of Cosmic Spherules from the Mesoproterozoic Strata and its Significance—in Case of the Ming Tombs Area, Beijing

AbstractThis study covers cosmic spherules derived from the Mesoproterozoic Dahongyu Formation in the Ming Tombs area, Beijing. The cosmic spherules include iron oxide cosmic spherules, carbonaceous chondrites, and atomic iron “steely bead”‐shaped cosmic spherules. The mineral assemblage of silicon carbide, forsterite, zircon, and glass spherules and fragments were picked from melt‐silicified carbonate of the Mesoproterozoic Dahongyu Formation (ca. 1625 Ma). Cosmic spherule assemblages are solely discovered from sedimentary rocks in China. Platinum group elements (PGE) were determined for the first time in cosmic spherules and associated minerals. PGE comparative observation between meteorite and cosmic spherules is presented in this study. It is recognized that an extraterrestrial meteorite impact event might have occurred in the Dahongyu Stage. The main evidence is a large number of iron cosmic spherules in silicified oncolitic limestone, and associated cosmic silicon carbide, glass spherules, and fragments, as well as the presence of forsterite. The impact‐volcanic crater is characteristic of a big black shale block dropped into the bended silicified limestone.

Zircon-hosted melt inclusion record of silicic magmatism in the Mesoproterozoic St. Francois Mountains terrane, Missouri: Origin of the Pea Ridge iron oxide-apatite-rare earth element deposit and implications for regional crustal pathways of mineralization

Voluminous silicic magmatism was coeval with iron ore mineralization in the St. Francois Mountains terrane in southeast Missouri, part of the broader Mesoproterozoic Granite-Rhyolite province along the eastern margin of Laurentia. Some of the iron deposits contain extraordinary endowments of critical elements, such as the Pea Ridge iron oxide-apatite (IOA) deposit, which has an average grade of ∼12 wt% rare earth oxides in breccia pipes that flank the ore body. To assess the role of silicic magmatism in the genesis of the Pea Ridge deposit, we present a high-spatial resolution study of zircon-hosted melt inclusions from rhyolitic ash-flow tuffs. Melt inclusion data are combined with textural, geochemical, and geochronological analyses of zircon hosts to elucidate the magmatic-hydrothermal evolution of the Pea Ridge system. Two contemporaneous silicic igneous centers in the St. Francois Mountains terrane, Bourbon and Eminence, were studied for comparison. Pea Ridge melt inclusions are trachydacitic to rhyolitic (∼63–79 wt% SiO2, ∼5.6–11.7 wt% Na2O + K2O) with very high Cl in the least-evolved and most alkaline melt inclusions (∼2000–5000 ppm Cl). Rare earth elements (REE) in melt inclusions have identical chondrite-normalized patterns to the mineralized breccia pipes, but with systematically lower absolute concentrations. Haplogranite ternary pressures range from ∼0.5 to 10 kbar, with an average of ∼2–3 kbar (7–12 km depth), and liquidus temperatures are ∼850–950 °C, with an average of ∼920 °C. Silicate and phosphate mineral inclusions have compositions that overlap minerals from the iron ore body and breccia pipes, recording a transition from igneous to hydrothermal zircon growth. Igneous iron oxide inclusions have compositions that indicate Pea Ridge magmas were reduced to moderately oxidized (log fO2 of −0.8 to −1.84 ΔNNO). Zircons from two Pea Ridge samples have 207Pb/206Pb concordia ages of 1456 ± 9 Ma and 1467 ± 13 Ma that overlap published ages for the breccia pipes and iron ore zones of the Pea Ridge deposit. A population of texturally and chemically disrupted zircons have discordant domains that correspond to high Fe, U, and REE concentrations, consistent with the unique geochemical attributes of the IOA-REE ore body. Inherited cores in Pea Ridge and Bourbon zircons have concordant 207Pb/206Pb dates of 1550–1618 Ma, providing direct evidence of cratonic basement beneath these centers. Oxygen isotope data for inherited and autocrystic igneous zircons span from mantle to crustal values (δ18Ozircon = 5.5–7.9‰). Our data are consistent with a model in which metasomatized mantle components were mixed with cratonic and accreted crustal material in a back-arc or rifted segment of a volcanic arc, with ore fluids derived from Cl-rich melts to transport Fe and REE in a long-lived (tens of Myr), pulsed, magmatic-hydrothermal system. Bourbon, which also possesses IOA mineralization, shares key petrologic similarities with the Pea Ridge system, whereas Eminence, which is not mineralized, has disparate geochemical and isotopic signatures that indicate it formed in a different crustal setting. The location of Pea Ridge and Bourbon along a cratonic margin may have been important in focusing silicic melts and mineralization in the upper crust, serving as a guide for future exploration efforts.

Evaluation of materials for iodine and technetium immobilization through sorption and redox-driven processes.

Radioactive iodine-129 (129I) and technetium-99 (99Tc) pose a risk to groundwater due to their long half-lives, toxicity, and high environmental mobility. Based on literature reviewed in Moore et al. (2019) and Pearce et al. (2019), natural and engineered materials, including iron oxides, low-solubility sulfides, tin-based materials, bismuth-based materials, organoclays, and metal organic frameworks, were tested for potential use as a deployed technology for the treatment of 129I and 99Tc to reduce environmental mobility. Materials were evaluated with metrics including capacity for IO3- and TcO4- uptake, selectivity and long-term immobilization potential. Batch testing was used to determine IO3- and TcO4- sorption under aerobic conditions for each material in synthetic groundwater at different solution to solid ratios. Material association with IO3- and TcO4- was spatially resolved using scanning electron microscopy and X-ray microprobe mapping. The potential for redox reactions was assessed using X-ray absorption near edge structure spectroscopy. Of the materials tested, bismuth oxy(hydroxide) and ferrihydrite performed the best for IO3-. The commercial Purolite A530E anion-exchange resin outperformed all materials in its sorption capacity for TcO4-. Tin-based materials had high capacity for TcO4-, but immobilized TcO4- via reductive precipitation. Bismuth-based materials had high capacity for TcO4-, though slightly lower than the tin-based materials, but did not immobilize TcO4- by a redox-drive process, mitigating potential negative re-oxidation effects over longer time periods under oxic conditions. Cationic metal organic frameworks and polymer networks had high Tc removal capacity, with TcO4- trapped within the framework of the sorbent material. Although organoclays did not have the highest capacity for IO3- and TcO4- removal in batch experiments, they are available commercially in large quantities, are relatively low cost and have low environmental impact, so were investigated in column experiments, demonstrating scale-up and removal of IO3- and TcO4- via sorption, and reductive immobilization with iron- and sulfur-based species.

Retrieval of aerosol components directly from satellite and ground-based measurements

Abstract. This study presents a novel methodology for the remote monitoring of aerosol components over large spatial and temporal domains. The concept is realized within the GRASP (Generalized Retrieval of Aerosol and Surface Properties) algorithm to directly infer aerosol components from the measured radiances. The observed aerosols are assumed to be mixtures of hydrated soluble particles embedded with black carbon, brown carbon, iron oxide, and other (non-absorbing) insoluble inclusions. The complex refractive indices of the dry components are fixed a priori (although the refractive index of the soluble host is allowed to vary with hydration), and the complex refractive indices of the mixture are computed using mixing rules. The volume fractions of these components are derived along with the size distribution and the fraction of spherical particles, as well as the spectral surface reflectance in cases when the satellite data are inverted. The retrieval is implemented as a statistically optimized fit in a continuous space of solutions. This contrasts with most conventional approaches in which the type of aerosol is either associated with a pre-assumed aerosol model that is included in a set of look-up tables, or determined from the analysis of the retrieved aerosol optical parameters (e.g., single scattering albedo, refractive index, among others, provided by the AERONET retrieval algorithm); here, we retrieve the aerosol components explicitly. The approach also bridges directly to the quantities used in global chemical transport models. We first tested the approach with synthetic data to estimate the uncertainty, and then applied it to real ground-based AERONET and spaceborne POLDER/PARASOL observations; thus, the study presents a first attempt to derive aerosol components from satellite observations specifically tied to global chemical transport model quantities. Our results indicate aerosol optical characteristics that are highly consistent with standard products (e.g., R of ∼0.9 for aerosol optical thickness) and demonstrate an ability to separate intrinsic optical properties of fine- and coarse-sized aerosols. We applied our method to POLDER/PARASOL radiances on the global scale and obtained spatial and temporal patterns of the aerosol components that agree well with existing knowledge on aerosol sources and transport features. Finally, we discuss limitations and perspectives of this new technique.

Preparation and Adsorptive Performance of Transition Metal Oxide Nanoparticles in Removal of Fe(III) Ions

In this study, we focus on preparation and adsorptive performance of transition metal oxide nanoparticles in removal of Fe(III) ions. The prepared nanoparticles including iron oxide (Fe2O3), cobalt oxide (Co3O4) and manganese oxide (Mn2O3/Mn3O4) nanocomposite provide a good affinity for Fe(III) ions adsorption from aqueous systems. Among them, Fe(III) ions were adsorbed by manganese oxide (Mn2O3/Mn3O4) nanocomposite with a higher removal ratio compared to the other nanoparticles.

Cost effective, industrially viable production of Fe2O3 nanoparticles from laterites and its adsorption capability

Laterite is an iron-rich earth material containing naturally occurring minerals such as hematite (Fe2O3), magnetite (Fe3O4), goethite (Fe3+O(OH)), gibbsite (Al(OH)3) and kaolinite (Al2Si2O5(OH)4). Even though these laterites are negligibly used as a cheap raw material in the brick manufacturing industry, they could be used in the synthesis of advanced materials including iron oxide nanoparticles and nanocomposites for a broad range of applications. Therefore, for the first time, this study focuses on the synthesis of iron oxide nanoparticles using laterites as a cheap raw material. In this method, first, iron and aluminium components of laterites were extracted into hydrochloric acid as their corresponding metallic ions. The extracted solution was then, mixed with sodium dodecyl sulphate (SDS) and the mixture was added dropwise to a basic solution maintaining the pH around 14 while stirring. The obtained ferric hydroxide nanoparticles were calcined to obtain iron oxide nanoparticles. The obtained nanoparticles were spherical shaped particles in the particle size range of 20–50 nm. These nanoparticles are characterized using x-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) and inductively coupled plasma mass spectrometry (ICP-MS). Furthermore, these synthesized nanoparticles showed superior adsorption capacity of Cr3+ ions from an aqueous solution, demonstrating its ability to remove heavy metals, which is a crucial factor for water filtration applications.

Fracture failure analysis and research on drive shaft of positive displacement motor

In this paper, microstructures and mechanical properties of the fractured drive shaft are investigated by visual inspection, metallographic analysis, scanning electron microscopy, and tensile and impact tests. The composition, structure and mechanical properties of the drive shaft materials are tested to meet the standards. The fracture surface is mainly characterized by dimples and a small amount of quasi-cleavage by microscopic analysis, which indicates that the fracture surface is dominated by ductile fracture. At the bottom of the sample pit, there are a large number of grey inclusions, which are turned to be iron oxides through EDS spectrum analysis. So, the existence of a large number of iron oxide inclusions in the metal will inevitably have a serious impact on the performance of drive shaft. The finite element analysis shows that the stress on the cylindrical surface of the external thread near the shoulder will gradually increase greatly and the rupture risk will increase with the increase of the torque and that it will also fails due to the relatively high stress on the root of the first tooth of thread. The maximum stress near the thread shoulder is close to the yield limit of the material when the borehole curvature is larger and the bending load will lead to stress concentration on the optical axis section at the shoulder, which will affect the safety of drive shaft. Because there are a large number of inclusions in raw materials and the conditions in the well are complex, the carrying capacity of drive shaft decreases and fracture of the drive shaft is finally caused. The maximum stress value of the improved drive shaft is lower than that before the improvement through the comparative analysis. It shows that the safety factor and service life of the drive shaft can be improved by the improved design.

Classification of iron oxide aerosols by a single particle soot photometer using supervised machine learning

Abstract. Single particle soot photometers (SP2) use laser-induced incandescence to detect aerosols on a single particle basis. SP2s that have been modified to provide greater spectral contrast between their narrow and broad-band incandescent detectors have previously been used to characterize both refractory black carbon (rBC) and light-absorbing metallic aerosols, including iron oxides (FeOx). However, single particles cannot be unambiguously identified from their incandescent peak height (a function of particle mass) and color ratio (a measure of blackbody temperature) alone. Machine learning offers a promising approach for improving the classification of these aerosols. Here we explore the advantages and limitations of classifying single particle signals obtained with a modified SP2 using a supervised machine learning algorithm. Laboratory samples of different aerosols that incandesce in the SP2 (fullerene soot, mineral dust, volcanic ash, coal fly ash, Fe2O3, and Fe3O4) were used to train a random forest algorithm. The trained algorithm was then applied to test data sets of laboratory samples and atmospheric aerosols. This method provides a systematic approach for classifying incandescent aerosols by providing a score, or conditional probability, that a particle is likely to belong to a particular aerosol class (rBC, FeOx, etc.) given its observed single particle features. We consider two alternative approaches for identifying aerosols in mixed populations based on their single particle SP2 response: one with specific class labels for each species sampled, and one with three broader classes (rBC, anthropogenic FeOx, and dust-like) for particles with similar SP2 responses. Predictions of the most likely particle class (the one with the highest mean probability) based on applying the trained random forest algorithm to the single particle features for test data sets comprising examples of each class are compared with the true class for those particles to estimate generalization performance. While the specific class approach performed well for rBC and Fe3O4 (≥99 % of these aerosols are correctly identified), its classification of other aerosol types is significantly worse (only 47 %–66 % of other particles are correctly identified). Using the broader class approach, we find a classification accuracy of 99 % for FeOx samples measured in the laboratory. The method allows for classification of FeOx as anthropogenic or dust-like for aerosols with effective spherical diameters from 170 to >1200 nm. The misidentification of both dust-like aerosols and rBC as anthropogenic FeOx is small, with <3 % of the dust-like aerosols and <0.1 % of rBC misidentified as FeOx for the broader class case. When applying this method to atmospheric observations taken in Boulder, CO, a clear mode consistent with FeOx was observed, distinct from dust-like aerosols.

Selective ultrasonic assisted synthesis of iron oxide mesoporous structures based on sulfonated melamine formaldehyde and survey of nanorod/sphere, sphere and core/shell on their catalysts properties for the Biginelli reaction.

Sulfonated melamine-formaldehyde including iron oxide nanoparticles were synthesized by sulfonation of melamine-formaldehyde and then Fe3O4 nanoparticles were bounded onto the surface of sulfonated melamine-formaldehyde (SMF). Two different iron oxide nanostructures including nanorods/spheres and nanospheres on sulfonated melamine-formaldehyde (SMF/Fe3O4) were obtained only by modifying the time of radiation from 4 to 8 h in our synthetic method. Furthermore core/shell (Fe3O4@SMF) was prepared by entrapping Fe3O4 magnetic nanoparticles as the core and sulfonated melamine-formaldehyde as the outer shell. The prepared components were characterized via, Fourier transform infrared spectroscopy (FT-IR), titration, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, Barret-Joyner-Halenda (BJH) analysis, vibrating sample magnetometer (VSM), energy-dispersive X-ray (EDX) spectroscopy, and thermal gravimetric analysis (TGA). According to obtained results, the synthesized products had a thermal stability near 180 °C, particle-size distribution around of 20-140 nm and surface area between 6 and 10 m2/g. In this study, vapor was used as a heat source. These effective and magnetically recoverable catalysts were employed for the synthesis of numerous 3,4-dihydropyrimidin-2(1H)-ones by utilizing aldehydes, ethylacetoacetate and urea. Functional easiness, excellent yields, short reaction time, the simplicity of work-up or filter, and thermal stability of these catalysts created them as appropriate heterogeneous systems and acceptable alternative to different heterogeneous catalysts.

바이오센서 응용을 위한 페록시다아제 모방 나노 소재

Biocatalysts, referred as enzymes, have been widely used in life, industrial, medical, and biological fields due to their high catalytic activity and substrate specificity for specific reaction. However, it has disadvantages in industrial applications due to the drawbacks in its characteristics as a catalyst, such as the high cost, the narrow operation conditions in terms of pH and temperature, and the low durability. Recently, many studies on nanozymes for replacing enzymes have been widely conducted to overcome these drawbacks. The nanozyme has a relatively wide pH and temperature operation range as compared with the enzyme, which is a kind of protein, and has a high durability over a long period of time. It is also expected to be able to be mass-produced at relatively low cost. However, the nanozymes still lacks of the substrate specificity, which is one of the most important features of enzymes. Furthermore, only few nanozymes have been reported which exhibits higher or comparable catalytic activity compared with enzymes. This review first discusses the classification of the nanozymes and the corresponding catalytic reactions, focusing on the most developed peroxidase -mimicking nanozymes. Then, it summarizes the most effective peroxidase nanozymes including iron oxides, nanocarbon, and iron- and carbon composite materials and their corresponding reaction mechanisms. After that, the nanotechnology- based approaches to improve the catalytic activity of nanozymes as well as the substrate specificity are covered. Furthermore, the current major application of nanozyme to the biosensor are introduced. Finally, the future directions for nanozyme researches and the applications are suggested.

Multi-stage adsorptive purification process for improving desulfurization performance of biogas

In this study, an experimental investigation was performed to suggest and demonstrate a multi-stage adsorption process that can simultaneously and more effectively remove major impurities (e.g., H2S, COS, CS2, and siloxanes D4 and D5) from methane- and carbon dioxide-rich biogas. Commercially available adsorbents, including iron oxide (IO), iron oxide hydroxides (IH and IHS), activated carbon (AC), impregnated activated carbon (IAC), silica gels (A2 and NS10), and zeolites (5A and 13X) were used as the candidate adsorbents. Five candidate adsorbents were first selected by dynamic adsorption analysis of each individual adsorbent for binary gas mixtures containing a trace impurity gas in a nitrogen balance; subsequently, three adsorbents were selected as the most promising candidates for the multi-stage adsorption process via dynamic breakthrough measurements using a simulated biogas mixture. Furthermore, using dynamic breakthrough tests on a series of configurations based on a tandem arrangement of the three adsorbents using the simulated biogas mixture, it was demonstrated that the optimal packing configuration for the multi-stage adsorptive purification process, in which the maximum increase in breakthrough time was achieved, consisted of AC, A2, and IHS along the gas-flow direction.

Advances in Applications of Metal Oxide Nanomaterials as Imaging Contrast Agents

Medical diagnosis relies on imaging modalities to reveal abnormalities in organs or existence of tumorous lesion. Application of contrast agents alongside imaging techniques is essential in order to obtain high contrast images with distinguishable features. Contrast agents delivered and accumulated in target sites can enhance local signal generation and solve the inherent lack of contrast in imaging techniques. As such, various contrast agents are developed for modalities like computed tomography (CT), magnetic resonance imaging (MRI), and photoacoustic imaging (PAI). For many of these techniques, metal‐based agents possess the desired properties for signal and contrast enhancement. Metal oxide nanomaterials present a simple platform for metal‐based contrast agents with tunable structure, magnetic and optical properties, surface chemistry, and pharmacokinetics. These can be controlled through synthesis, redox reactions, and surface modification to produce desirable nanoparticles. In this review, recent advances in the development of metal oxide imaging agents are highlighted. Various metal oxide species are discussed, including iron oxides, gadolinium oxides, manganese oxides, tungsten oxides and bronzes, molybdenum oxides, and other oxides of titanium, tantalum, etc. Imaging capability and performance of these metal oxides are presented, and novel functionalization strategies are presented. Finally, recommendations for future research in this area are proposed.

Fluorescent Fe3O4 Quantum Dots for H2O2 Detection

A universal green synthesis approach of several quantum dots (QDs), including iron oxide (Fe3O4) QDs, gold (Au) QDs, zirconium oxide (ZrO2) QDs, and graphene (Gr) QDs, was demonstrated in this stud...

Identification of corrosion products and 3D distribution in reinforced concrete using X-ray micro computed tomography

Abstract The main purpose of this study is to non-destructively monitor the formation and development of corrosion products in reinforced mortar with the help of X-ray micro computed tomography (X-ray µCT). A new method based on the relationship between the linear attenuation coefficient and CT number as well as greyscale value is built to identify different type of corrosion products. Based on this method, two categories of corrosion products including iron oxides and iron hydroxides are identified in this research. Additionally, the corrosion mechanism and the interaction between different types of corrosion products are discussed according to the characteristics of corrosion evolution. Furthermore, the volumetric expansion ratio of corrosion products is quantified (from 2.71 to 3.97). This method provides a new angle to investigate the formation and development of reaction products, which contributes to further understand the corrosion process in reinforced concrete.