Single-walled carbon nanotubes (SWNT) have a strong and stable near-infrared (nIR) fluorescence that can be used to selectively detect target analytes, even at the single molecule level, through changes in either their fluorescence intensity or emission peak wavelength. SWNTs have been employed as NIR optical sensors for detecting a variety of analytes. However, high costs, long fabrication times, and poor distributions limit the current methods for immobilizing SWNT sensors on solid substrates. Recently, our group reported a protocol for SWNT immobilization with high fluorescence yield, longevity, fluorescence distribution, and sensor response, unfortunately this process takes 5 days to complete. Herein we report an improved method to immobilize SWNT sensors that only takes 2 days and results in higher fluorescence intensity while maintaining a high level of SWNT distribution. We performed surface morphology and chemical composition tests on the original and new synthesis methods and compared the sensor response rates. The development of this new method of attaching SWNT sensors to a platform allows for creation of a sensing system in just 2 days without sacrificing the advantageous characteristics of the original, 5-day platforms.

Carbon fibers of polyacrylonitrile (PAN) type were coated with nickel nanoparticles using a chemical reduction method in alkaline hydrazine bath. The carbon fibers were firstly heated at 400 °C and then chemically treated in hydrochloric acid followed by nitric acid to clean, remove any foreign particles and functionalized its graphitic surfaces by introducing some functional groups. The functionalized carbon fibers were coated with nickel to produce 10 wt% Cf/Ni nanocomposites. The uncoated heat treated and the nickel coated carbon fibers were investigated by SEM, EDS, FTIR and XRD to characterize the particle size, morphology, chemical composition and the crystal structure of the investigated materials. The nickel nanoparticles were successfully deposited as homogeneous layer on the surface of the functionalized carbon fibers. Also, the deposited nickel nanoparticles have quazi-spherical shape and 128–225 nm median particle size. The untreated and the heat treated as well as the 10 wt% Cf/Ni nanocomposite particles were further reinforced in ethylene vinyl acetate (EVA) polymer separately by melt blending technique to prepare 0.5 wt% Cf-EVA polymer matrix stretchable conductive composites. The microstructures of the prepared polymer composites were investigated using optical microscope. The carbon fibers as well as the nickel coated one were homogenously distributed in the polymer matrix. The obtained samples were analyzed by TGA. The addition of the nickel coated carbon fibers to the EVA was improved the thermal stability by increasing the thermal decomposition temperature Tmax1 and Tmax2. The electrical and the mechanical properties of the obtained 10 wt% Cf/Ni nanocomposites as well as the 0.5 wt% Cf-EVA stretchable conductive composites were evaluated by measuring its thermal stability by thermogravimetric analysis (TGA), electrical resistivity by four probe method and tensile properties. The electrical resistivity of the fibers was decreased by coating with nickel and the 10 wt% Cf/Ni nanocomposites has lower resistivity than the carbon fibers itself. Also, the electrical resistivity of the neat EVA is decreased from 3.2 × 1010 to 1.4 × 104 Ω cm in case of the reinforced 0.5 wt% Cf/Ni-EVA polymer composite. However, the ultimate elongation and the Young’s modulus of the neat EVA polymer was increased by reinforcing with carbon fibers and its nickel composite.

Despite enormous popularity of graphene oxide (GO) several open questions remain regarding the structure and properties of this material. One of those questions is the role of a graphite precursor on the properties of GO product. In this study, we investigate the oxidation process and the structure of GO products, made from the four different graphite precursors: synthetic graphite, two natural flaky graphites, and expanded graphite. The highest rate of the oxidation reaction was registered for the small particle size synthetic graphite. Thermal expansion of natural flaky graphite did not significantly affect the rate of the reaction. The nature of the graphite precursor does not notably affect the chemical composition of the synthesized GO products. However, it affects stability of respective aqueous dispersions. The solutions of the three GO samples, prepared from the natural graphite sources demonstrate excellent stability due to complete exfoliation of GO to single-atomic-layer sheets. GO from synthetic graphite forms unstable dispersions due to the presence of numerous multi-layered particles. This, in turn, is explained by the presence of not fully graphitized, amorphous inclusions in synthetic graphite. Our observations suggest that synthetic graphite should not be used as GO precursor when the ability to completely exfoliate and the stability of dispersions are critical for intended applications.

In the current study, the epoxy material was mixed with 10%, and 30% weight percent carbon material as filler in different thicknesses (1 cm, 1.5 cm, and 2 cm). Transmission electron microscope (TEM) measurements showed the average size of the nano-carbon was 20 nm with a standard deviation of 5 nm. The morphology of samples was examined using scanning electron microscopy (SEM), which showed the flatness of the epoxy surface, and when the content of carbon increases, the connection between the epoxy array and carbon increases. The compression test indicates the effect of nano-size on enhancing the mechanical properties of the studied samples. To survey the shielding properties of the epoxy/carbon composites using gamma-rays emitted from Am-241, Ba-133, Cs-137, Co-60, and Eu-152 sources, which covered a wide range of energies from 0.059 up to 1.408 MeV, the gamma intensity was measured using the NaI (Tl) detector. The linear and mass attenuation coefficients were calculated by obtaining the area under each peak of the energy spectrum observed from Genie 2000 software in the presence and absence of the sample. The experimental results obtained were compared theoretically with XCOM software. The comparison examined the validity of experimental results where the relative division rate ranged between 0.02 and 2%. Also, the measurement of the relative division rate between linear attenuation coefficients of microand nano-composites was found to range from 0.9 to 21% The other shielding parameters are calculated at the same range of energy, such as a half-value layer (HVL), mean free path (MFP), tenth-value layer (TVL), effective atomic number (Zeff), and the buildup factors (EBF and EABF). The data revealed a consistent reduction in the particle size of the shielding material across various weight percentages, resulting in enhanced radiation shielding capabilities. The sample that contains 30% nano-carbon has the lowest values of TVL (29.4 cm) and HVL (8.85 cm); moreover, it has the highest value of the linear attenuation coefficient (LAC), which makes it the best in its ability to attenuate radiation.

Vespa mandarinia (Vespidae: Hymenoptera) is one of the two largest true hornets known to science. The species is a noted predator of social Hymenoptera and a significant pest of managed honey bees in its native range, but is also known to feed on a wide variety of other species when available. Most of the prey records for V. mandarinia are derived from visual observations in Japan, with sparse observations from other parts of its native range. A population of V. mandarinia was detected in North America in 2019 and five nests were removed between 2019 and 2021. We extracted DNA from larval meconia from four nests collected in Washington State, USA, and amplified the CO1 region to determine the potential prey base. We compared these with sequences generated from three nests in the Republic of Korea, and with prey pellets collected from foraging hornets at several locations in Korea. Results indicate that the prey base was much wider in the ROK than the USA, although social Hymenoptera were the most abundant and common prey items in both regions. Prey range seems to be bound by an intersection of organism size and local biodiversity, with little evidence to suggest that the latter is a limiting factor in colony success.

The untreated effluent dropping into the environment from various textile industries is a major issue. To solve this problem, development of an efficient catalyst for the degradation of macro dye molecules has attracted extensive attention. This work is mainly focused on the synthesis of nickel–manganese sulfide decorated with rGO nanocomposite (Ni–Mn-S/rGO) as an effective visible photocatalyst for degradation of textile toxic macro molecule dye. A simple hydrothermal method was used to synthesize Ni–Mn-S wrapped with rGO. The prepared composites were characterized using various techniques such as X-ray diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red spectrometer (FTIR), and ultra violet–visible (UV–Vis) spectroscopy. The photocatalytic performance of nickel sulfide (NiS), manganese sulfide (MnS), nickel–manganese sulfide (Ni–Mn-S), and Ni–Mn-S/rGO nanocomposite was assessed by analyzing the removal of acid yellow (AY) and rose bengal (RB) dyes under natural sun light. Among these, the Ni–Mn-S/rGO nanocomposite showed the high photocatalytic degradation efficiency of AY and RB dyes (20 ppm concentration) with efficiency at 96.1 and 93.2%, respectively, within 150-min natural sunlight irradiation. The stability of photocatalyst was confirmed by cycle test; it showed stable degradation efficiency even after five cycles. This work confirms that it is an efficient approach for the dye degradation of textile dyes using sulfide-based Ni–Mn-S/rGO nanocomposite.

Zeolitic imidazolate frameworks (ZIFs) along with carbon nanofibers and polyaniline composite have been explored as an electrochemical sensing platform in nitrite measurement at trace level. Owing to their topology, high surface area and porous structure, these metal–organic frameworks (MOFs) find widespread utility in different application domains. Nitrites are widely used as preservatives in dairy, meat products, and packaged food stuffs. They form N-nitrosamines, which are potential carcinogens and cause detrimental health effects. These ZIF-based MOFs along with carbon nanofibers and polyaniline have emerged as an efficient electrochemical sensing material. The composite has been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and BET surface area studies. The electrochemical performance of the composite has been evaluated by forming as a thin film of composite on the surface of glassy carbon electrode and studying its impedance as well as electrochemical sensing behavior. The sensor exhibited good analytical response in nitrite measurement with a limit of detection of 8.1 μM. The developed sensing platform has been successfully applied to quantify the nitrite levels from water samples. The results obtained are in good agreement with the results of standard protocol.

The nanostructured dysprosium oxide ( Dy2O3) was synthesized by the co-precipitation method and incorporated with graphitic carbon nitride (g-C3N4) using the ultrasonication method. The resultant product is denoted as Dy2O3/ g-C3N4 nanocomposite which was further used for electrochemical sensing of riboflavin (RF). The physicochemical properties of Dy2O3/ g-C3N4 nanocomposite were examined using several characterization techniques. The obtained results exhibit the nanocomposite formation with the preferred elemental compositions, functional groups, crystalline phase and desired surface morphology. The electrocatalytic performance of Dy2O3/ g-C3N4 nanocomposite was scrutinized with a glassy carbon electrode (GCE) via differential pulse voltammetry (DPV) and cyclic voltammetry (CV) techniques with the conventional three-electrode system. The modified electrode distributes more active surface area suggesting high electrocatalytic activity for the RF detection with two linear ranges (0.001–40 μM and 40–150 μM), a low detection limit of 48 nM and sound sensitivity (2.5261 μA μM−1 cm− 2). Further, the designed sensor possesses high selectivity, excellent stability, repeatability and reproducibility. Finally, the fabricated sensor was successfully estimated for the detection of RF in actual food sample analysis using honey and milk with better recovery.

In this research, in order to increase the oxidation resistance of graphite, kaolin and alumina powder with different ratios (26A-74S, 49A-51S, 72A-28S) and slurry method were used to create an aluminosilicate coating on the graphite substrate. In order to reduce the difference in the coefficients of thermal expansion of graphite with aluminosilicate coating, aluminum metaphosphate coating as an interlayer was prepared on the surface of graphite by cathodic electrochemical treatment. The isothermal oxidation test of the samples was carried out in air at a temperature of 1250 °C for 1, 3 and 5 h. The microstructure, chemical composition, and phase components of the coating were, respectively, analyzed by scanning electron microscope equipped with an energy-dispersive spectrometer and X-ray diffraction. The results indicated that, by increasing the withdrawal speed of the samples in slurry method, the amount of changes in the weight of the samples has increased and therefore had a direct effect on oxidation. In addition, it was approved that, at high-temperature oxidation, AlPO4 glass phase forms on aluminum metaphosphate interlayer which retards graphite oxidation. Along with aluminum metaphosphate, aluminosilicate coating also produces a glass phase which fills and seals the voids on the surface which prevents the oxygen to reach the surface of graphite. The created double-layer coating including an interlayer of aluminum metaphosphate + slurry coating prepared with the ratio of 26A-74S as the optimal coating in this research was able to increase the oxidation resistance of graphite by 73% at a temperature of 1250 °C.

The development of heteroatoms doped inorganic nanocrystal-carbon composites (INCCs) has attained a great focus for energy applications (energy production and energy storage). A precise approach to fabricate the INCCs with homogenous distribution of the heteroatoms with an appropriate distribution of metal atoms remains a challenge for material scientists. Herein, we proposed a facile two-step route to synthesize INCC with doping of metal (α-Fe2O3) and non-metals (N, P, O) using hydrogel formed by treating hexachlorocyclotriphosphazene (HCCP) and 3, 4, 5-trihydroxy benzoic acid (Gallic acid). Metal oxide was doped using an extrinsic doping approach by varying its content and non-metallic doping by an intrinsic doping approach. We have fabricated four different samples (INCC-0.5%, INCC-1.0%, INCC-1.5%, and INCC-2.0%), which exhibit the uniform distribution of the N, P, O, and α-Fe2O3 in the carbon architecture. These composite materials were applied as anode material in water oxidation catalysis (WOC); INCC-1.5% electro-catalyst confirmed by cyclic voltammetry (CV) with a noticeable catholic peak 0.85 V vs RHE and maximal current density 1.5 mA.cm−2. It also delivers better methanol tolerance and elongated stability than RuO2; this superior performance was attributed due to the homogenous distribution of the α-Fe2O3 causing in promotion of adsorption of O2 initially and a greater surface area of 1352.8 m2/ g with hierarchical pore size distribution resulting higher rate of ion transportation and mass-flux.

The ability to both assay the presence of, and to selectively remove ions in a solution is an important tool for waste water treatment in many industrial sectors, especially the nuclear industry. Nuclear waste streams contain high concentrations of heavy metals ions and radionuclides, which are extremely toxic and harmful to the environment, wildlife and humans. For the UK nuclear industry alone, it is estimated that there will be 4.9 million metric tonnes of radioactive waste by 2125, which contains a significant number of toxic radionuclides and heavy metals. This is exacerbated further by increased international growth of nuclear new build and decommissioning. Efforts to remove radionuclides have been focused on the development and optimisation of current separation and sequestering techniques as well as new technologies. Due to the large volumes of waste the techniques must be economical, simple to use and highly efficient in application. Magnetic nanoparticles (MNPs) offer a powerful enhancement of normal ion exchange materials in that they can be navigated to specific places using external magnetic fields and hence can be used to investigate challenges such as, pipework in preparation of decommissioning projects. They also have the potential to be fine-tuned to extract a variety of other radionuclides and toxic heavy metals. It has been demonstrated that with the right functional groups these particles become very strongly selective to radionuclides, such as Uranium. However, this new technology also has the potential to effectively aid nuclear waste remediation at a low cost for the separation of both radionuclides and heavy metals. In this work, we investigate the origin of the selectivity of superparamagnetic iron oxide nanoparticles (SPIONs) to Uranium by making systematic changes to the existing surface chemistry and determining how these changes influence the selectivity. Identifying the mechanism by which selected common nuclear related metals, such as Na(I), K(I), Cs(I), Ca(II), Cu(II), Co(II), Ni(II), Cd(II), Mg(II), Sr(II), Pb(II), Al(III), Mn(II), Eu(III) and Fe(III), are sorbed will allow for specific NP-target (nanoparticle) ion interactions to be revealed. Ultimately this understanding will provide guidance in the design of new targeted NP-ligand constructs for other environmental systems.

Echeveria is a genus belonging to the Crassulaceae family that comprises approximately 170 species. It is a representative plant known as a succulent with economic potential in the floriculture industry. Echeveria plants are widely distributed in dry environments and endemic to Mexico. These plants have a rosette formation and varied leaf colors and shapes, which are characteristics of interest for landscaping, cut flowers, or interior decoration. Given their range of locations in different climates or indoor conditions, it is important to have an understanding and knowledge of their leaf morphology and anatomy and how they function to provide optimum care and management. Owing to high demand in horticultural markets, many breeders have crossed their desired species. However, this method has progressively increased the number of species without proper records of parents or other natural unintended crossings, creating phylogenetic problems and identification issues. The use and understanding of phenotypes, anatomical data, and/or research to aid in taxonomic issues and improve cultural management practices have been reviewed and discussed in this paper. In this review, we have provided a brief background of Echeveria species, focusing on the challenges and studies that have attempted to address these issues.

The surface of carbon films deposited with inverted plasma fireballs is analysed in this paper. Measurements were conducted with Raman spectroscopy, atomic force microscopy and nanoindentation. The latter was used to obtain Young’s modulus as well as Martens and Vickers hardness. The roughness of the film was measured by atomic force microscopy and its thickness was measured. It was shown with Raman spectroscopy that the films are homogeneous in terms of atomic composition and layer thickness over an area of about 125 × 125 mm. Furthermore, it was demonstrated that inverted plasma fireballs are a viable tool for obtaining homogeneous, large area carbon films with rapid growth and very little energy consumption. The obtained films show very low roughness.

There is an ever growing interest in the development of biochar from a large variety of agrowastes. Herein, the main objective is the conversion of pomegranate peel powder biochar and its post-functionalization by phosphoric acid treatment, followed by arylation organic reaction. The latter was conducted using in situ-generated diazonium salts of 4-aminobenzoic acid ( H2N-C6H4-COOH), sulfanilic acid ( H2N-C6H4-SO3H) and Azure A dye. The effect of diazonium nature and concentration on the arylation process was monitored using thermal gravimetric analysis (TGA) and Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). SEM pictures showed micrometer-sized biochar particles with tubular structure having about 10–20 μm-wide channels. SEM studies have shown that arylation did not affect the morphology upon arylation. The porous structure did not collapse and withstood the arylation organic reaction in acid medium did not collapse upon arylation. TGA and Raman indicated gradual changes in the arylation of biochar at initial concentrations 10– 5, 10– 4 and 10– 3 mol L− 1 of 4-aminobenzoic acid. The detailed Raman spectra peak fittings indicate that the D/G peak intensity ratio leveled off at 3.35 for 4-aminobenzoic acid initial concentration of 10– 4 mol L− 1, and no more change was observed, even at higher aryl group mass loading. This is in line with formation of oligoaryl grafts rather than the grafting of new aryl groups directly to the biochar surface. Interestingly, Azure A diazonium salt induced much lower extent of surface modification, likely due to steric hindrance. To the very best of our knowledge, this is the first report on diazonium modification of agrowaste-derived biochar and opens new avenues for arylated biochar and its applications.

Molten salt consisting primarily of eutectic LiCl-KCl is currently being used in electrorefiners in the Fuel Conditioning Facility at Idaho National Laboratory. Options are currently being evaluated for storing this salt outside of the argon atmosphere hot cell. The hygroscopic nature of eutectic LiCl-KCl makes is susceptible to deliquescence in air followed by extreme corrosion of metallic cannisters. In this study, the effect of occluding the salt into a zeolite on water sorption/desorption was tested. Two zeolites were investigated: Na-Y and zeolite 4A. Na-Y was ineffective at occluding a high percentage of the salt at either 10 or 20wt% loading. Zeolite-4A was effective at occluding the salt with high efficiency at both loading levels. Weight gain in salt occluded zeolite-4A (SOZ) from water sorption at 20% relative humidity and 40℃ was 17wt% for 10% SOZ and 10wt% for 20% SOZ. In both cases, neither deliquescence nor corrosion occurred over a period of 31 days. After hydration, most of the water could be driven off by heating the hydrated salt occluded zeolite to 530℃. However, some HCl forms during dehydration due to salt hydrolysis. Over a wide range of temperatures (320–700℃) and ramp rates (5, 10, and 20℃ min−1), HCl formation was no more than 0.6% of the Cl− in the original salt.

Carbon fibers are commonly used in many specialized, high-performance applications such as race cars and aircraft due to their lightweight and high durability. The most important stage in the production of carbon fibers is the carbonization process. During this process, carbon fibers are subjected to high temperatures in the absence of oxygen to prevent fibers from burning. Labyrinth seals are attached to a carbonization furnace to prevent airflow into the furnace and to assist in the elimination of off-gases. This study investigated flow characteristics inside a carbonization furnace and the effects of different geometric parameters of labyrinth seals such as labyrinth tooth shape, number of teeth, and tooth clearance. Varying carbonization furnace operating conditions were also studied in regard to flow behavior, including fiber movement and outlet vacuum pressure. A high working gas flow rate at the furnace inlet resulted in recirculation zones. Properly regulated gas flow from the main and labyrinth inlets enabled uniform flow around the fibers’ inlet and outlet which prevented air from being trapped in the reactor. Flow behavior was minimally effected by changes to labyrinth seal geometry such as tooth length, tooth clearance, and outlet pressure. However, the movement of fibers had a clear effect on flow characteristics in the furnace.

Fluorescent nanostructures based on carbon, or carbon dots, are attracting much attention and interest because of their diverse properties which can be applied in several fields of knowledge, such as optics, biomedicine, environmental research, among others. Such properties are in part, derived from its intrinsic luminescence from tunable functional groups. In this work, we produced carbon nanodots (CND) using agro-industrial residues, such as Lolium perenne and malt bagasse. The methods used were conventional hydrothermal syntheses and microwave-assisted hydrothermal synthesis. To the best of our knowledge, this is the first time that carbon dots synthesized from this ryegrass type are reported. The synthesis methods were one step (no catalyst, base, or acid were added for passivation), and the functional groups responsible for the luminescence and high solubility in water were identified by infrared spectroscopy, being mainly C=O, C–OH, C–N, and N–H. According to our theoretical studies, the C=O group introduced a new energy level for electronic transitions that can affect the emission properties. Fluorescence images of osteoblasts using CNDs were acquired and their chelating property towards Pb2+ and Cr6+ detection was tested.

The carbon-based nanostructures are in limelight due to their widespread applications in nano-to-micro-scale technologies. The carbon dots are known for their unique physical, electrical, optical, chemical and biological properties. The carbon dots (CDs) are being produced through several well-developed synthesis methods, one of which is the green sonochemical. This method is preferred over others because it is a green source of energy, facile, fast, low-temperature process, non-toxic and less expensive. Despite the fact of using 90% less energy than other methods, this method has been overlooked in the published literature. It is possible to prepare pure and doped CDs of low toxicity and controlled physicochemical properties through sonochemical method. In recent years, sonochemically produced CDs have been tuned and characterized for a variety of applications. This review has explored the merits and demerits of sonochemical method in comparison to the other methods for the synthesis of pure CDs and their nanocomposites. The role of multiple factors in tailoring the specific parameters of CDs for their application in antibacterial, polymerization, tissue engineering, catalysis, bio-imagining, supercapacitors, drug delivery and electric devices is also elaborated in this review. This review also concludes on future directions in the applications of sonochemically produced CDs.