Metal-free N–S- and N–P-doped nanocarbon (SCNP and PCNP) electrocatalysts prepared through sustainable microwaveassisted synthesis using hemigraphis alternata plant leaves. The prepared heteroatom-doped nanocarbon materials are active catalysts for the two-electron oxygen reduction reaction (ORR) to produce 65–70% of hydrogen peroxide. As evidenced from the XPS, most proportion of the doped heteroatoms contain the oxygen functional groups in the nanocarbons. These attributes are the critical factors to see the selective two-electron transfer ORR for the PCNP and SCNP. This approach shed light on the critical role of dual heteroatoms doping and the oxygen functionalities in nanocarbon towards the selectivity of ORR. We believe that this method would allow the preparation of heteroatom that contains oxygen functionalities. Our work paves a sustainable way of preparation of nanocarbon based ORR catalysts that are only selective for two-electron transfer process.
Herein, the present work focuses on the effective counter electrode for dye-sensitized solar cells. The bottom–up approach was adapted to synthesize Mn2O3 nanorods via the hydrothermal method and the reduced graphene oxide was merged with Mn2O3 to prepare a nanocomposite. The prepared nanocomposites were subjected to physio-chemical and morphological characterizations which revealed the crystalline nature of Mn2O3 nanorods. The purity level rGO was characterized using the Raman spectrum and the Fourier transform infrared spectroscopy employed to find the functional groups. The morphological micrographs were visualized using SEM and TEM and the high aspect ratio Mn2O3 nanorods were observed with 5–7 nm and supported by rGO sheets. The electrocatalytic nature and corrosion properties of the counter electrode towards the iodide electrolyte were studied using a symmetrical cell. The as-synthesized nanocomposites were introduced as counter electrodes for DSSC and produced 4.11% of photoconversion efficiency with lower charge transfer resistance. The fabricated DSSC devices were undergone for stability tests for indoor and outdoor atmospheres, the DSSC stability showed 93% and 80% respectively for 150 days.
Six new species are described that are members of the New Zealand endemic genus Adalmus Reitter (Staphylinidae: Pselaphinae: Euplectitae: Trichonychini: Panaphantina): A. bullerensis sp. nov., A. kanierensis sp. nov., A. karekarensis sp. nov., A. mangamukaensis sp. nov., A. puberilumbus sp. nov., and A. serrilumbus sp. nov. In addition, Dalmisus Sharp is placed as a junior synonym of Adalmus (gen. syn.) and the species Dalmisus batrisodes Sharp, 1886, Plectomorphus longiceps Broun, 1913 and P. longipes Broun, 1912 are placed as junior synonyms of A. velutinus Reitter, 1885 spp. syn. Also, P. rugiceps Broun, 1921 is transferred to the genus Adalmus, comb. nov. Adalmus now holds eight species.
Calonecrinae represent a unique but small subfamily of Nitidulidae that is endemic to South Asia. Their habitats, the South Asian lowland forests, are under the imminent threat of degradation, posing a risk of rapid extinction for these species in their specific locales. Despite the looming threat to their existence, our understanding of this enigmatic group remains limited. We conducted an examination of museum and newly collected specimens, alongside a review of the literature, leading to the discovery of a new species, Calonecrus mindanaoensis, from Mindanao, Philippines. For the first time, the morphology of all immature stages of the Calonecrinae was described, with detailed photographs including SEM images. Additionally, their natural history was uncovered for the first time, revealing that all life stages are uniquely adapted to spending their entire life cycle within sticky resin. We re-evaluated the phylogenetic placement of the Calonecrinae by constructing a phylogenetic tree based on the mitochondrial genome. Calonecrinae are positioned within the Epuraeinae clade and show significant affinity with the genus Trimenus. Consequently, this study proposes reclassifying Calonecrinae as Calonecrini stat nov, an extremely modified tribe within the Epuraeinae.
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.
Environmental pollution has become an alarming issue for the modern world due to the extensive release of untreated chemical waste into freshwater bodies. Untreated chemical waste poses significant negative impacts on aquatic life and human health. The phenolic compounds are widely used in different industries for dyeing, as food preservatives, and for the production of pesticides. 2,4,6-Trichlorophenol (TCP) is among the most hazardous phenolic compounds that cause several serious health effects. Thus, it is important to monitor TCP in the environmental samples frequently. In the current work, it was aimed to develop a highly sensitive zinc oxide-doped (ZnO) reduce graphene oxide (rGO) composite-based electrochemical sensor for TCP monitoring in the real samples. In this regard, graphene oxide (GO) was simultaneously reduced and doped with ZnO using a facile microwave-assisted synthesis strategy. The resulting ZnO/rGO composite was successfully utilized to fabricate ZnO/rGO-modified glassy carbon electrode (ZnO/rGO/GCE) for the selective and trace level determination of TCP. The conductivity and electrocatalytic behaviors of ZnO/rGO/GCE were examined through different modes of electrochemical setup. Under the optimal operating conditions such as a scan rate of 80 mV.s−1, PBS electrolyte (pH 7.0), and the concentration range of 0.01–80 μM, the fabricated electrochemical sensor manifested outstanding responses for monitoring TCP. The limit of detection (LOD) and limit of quantification (LOQ) of the ZnO/rGO/GCE for TCP were found as 0.0067 μM and 0.019 μM, respectively. Moreover, the anti-interference profile and stable nature of ZnO/rGO/GCE made the suggested electrochemical sensor a superb tool for quantifying TCP in a real matrix.
Hybrid nanocomposites of aluminium (NHAMMCs) made from AA5052 are fabricated via stir casting route by reinforcing 12 wt% Si3N4 and 0.5 wt% of graphene for usage in aeronautical and automotive applications due to the lower density and higher strength to weight proportion. The wear characteristics of the NHAMMCs are evaluated for different axial load, rotational speed, sliding distance and sliding time based on Box-Behnken design (BBD) of response surface methodology (RSM). Orowan strengthening mechanism is identified from optical image which improves the strength of the composite. Outcomes show that with higher axial load and rotational speed, there is substantial increase in wear loss whereas with increased sliding distance and sliding time there is no considerable increase in wear loss due to the lubricating nature of the reinforced graphene particles since it has higher surface area to volume ratio. Besides, artificial intelligence approach of neuro-fuzzy (ANFIS) model is developed to predict the output responses and the results are compared with the regression model predictions. Prediction from ANFIS outplays the regression model prediction.
Goniaceritae is the most speciose supertribe of the subfamily Pselaphinae with more than 3,000 species worldwide. Brachyglutini is the only tribe within New Zealand Goniaceritae, comprised of 8 genera. Physobryaxis Hetschko is monotypic genus of the subtribe Brachyglutina. Although the adults of P. inflatus is close to the members of genus Gastrobothrus Broun, 1882, it is characterized by median antebasal fovea and antebasal sulcus on pronotum. In this study, we report six species of Physobryaxis examining 21 specimens. Illustrations of the habitus, diagnostic characters including male genitalia, and key to the species are also provided. Additionally, we present a distributional map divided into areas based on Crosby’s code.
Following the Antecedents, Methods, and Outcomes (AMO) framework, this paper contributes to a better understanding of corporate activism (CA) in an international context. Through an in-depth review of publications over the past 33 years, we aim to shed light on the rising trend of CA and identify its most important antecedents, manifestations, and the short-term and long-term consequences of CA. In this context, we focus particularly on cross-country differences. Guided by the scientific Procedures and Rationales for a Systematic Literature Reviews Protocol (SPAR-4-SLR), this paper offers a framework-based systematic literature review on CA. We observe that the topic of CA is somewhat underexplored in the literature. Moreover, CA is very often misinterpreted, and lines between CA and similar terms, such as Corporate Social Responsibility, CEO activism, and lobbying often remain blurred. Nevertheless, our review identifies a rising trend among companies to express their stance on various controversial issues. Reflecting this trend, we can also witness a substantial increase in the number of studies on CA over the past two years. Through the articles identified in our literature review, we improve the understanding of the common antecedents and manifestations of CA, but also observe a lack of conceptual clarity in many extant contributions on CA. As to the outcome of CA, the literature indicates that the long-term and shortterm consequences of CA also still call for further analysis. The international nature and ramifications of CA, recently highlighted by the considerable CA in response to the war between Russia and Ukraine and its spillover effect worldwide, is neglected in current research. Thus, given the international dimension of some CA there is a particular need to research both, national idiosyncrasies and international consequences of CA.
We study retailer app use and shopping behavior by investigating whether and how app adopters’ preferred store registration (PSR), a voluntary enrollment of store loyalty program, can lead to changes in purchase behaviors among the adopters in offline stores. A panel dataset from a large bakery franchise chain was studied using difference-in-differences with propensity score matching for causal inference. The results show that customers who participated in PSR increase their spending, compared to customers who did not. In addition, the results confirm that the PSR-spending relationship is moderated by customer and store characteristics; customers who visited infrequently and spent less prior to PSR participation increase their purchases, and they spend more at stores with better service quality.
Medicinal plant-derived carbon dots are eco-friendly and possess therapeutic properties. Among the medicinal plants studied throughout the world, Centella asiatica (L.) Urb. is known for its medicinal values, especially its neuroceutical and cogniceutical properties. This work discusses the green synthesis of carbon dots (CDs) using C. asiatica leaves as the carbon source via fast and cost-effective microwave-assisted method, and its physico-chemical characterization via UV–visible, fluorescence and FTIR spectrometry, XRD, SEM, AFM, TEM, SAED, EDX and zeta potential analyses. The study revealed quasi-spherical CDs having size ~ 3–6 nm, polycrystalline nature, and presence of various functional groups like –COOH, –H, =CH2 and C–O–C with UV absorption peaks at 213 and 322 nm. Interestingly, the C. asiatica-derived CDs exhibited blue fluorescence under UV with maximum emission wavelength of 460 nm when excited at 400 nm. Further, these CDs were evaluated for their biological applications, which uncovered their potential in therapeutics such as antimicrobial properties against both Gram-positive and Gram-negative bacteria at a dose of 10 μg, strong antioxidant activity with IC50 values of 165.28 and 128.48 μg mL− 1 in DPPH and H2O2 assays, respectively, and profound anti-inflammatory activity with IC50 value of 106.20 μg mL− 1 in protein denaturation assay. The CDs were also assessed for cytotoxicity using whole blood cells and were found to be safe for in vitro administration. Thus, the C. asiatica-derived CDs can be exploited for their potent biomedicinal properties. Fluorescent carbon dots (CDs) were prepared by microwave-assisted pyrolysis of Centella asiatica leaf extract and purification. The as synthesized CDs were subjected to various physico-chemical characterization and biomedical assays to understand its properties.
The rapid synthesis techniques and interesting multidisciplinary applications make carbon nanodots (CNDs) stand out from semiconductor quantum dots. Moreover, CNDs derived from green precursors have gained more importance beyond chemically derived CNDs due to sustainable synthesis opportunities. However, the presence of molecular impurities or intermediates or fluorophores was neglected during the entire process. Herein, we illustrate the sustainable synthesis of CNDs from Hemigraphis alternata plant leaves with extended carbonization procedure (3 and 9 min) along with simultaneous ethylene glycol and diethyl ether solvent treatment method for the successful removal of interfering fluorophores. To unravel the distinction between purified CNDs (P-CNDs) and organic fluorescent carbon nanostructures (org-FCNs), we carried out photophysical, structural, and morphological studies. A quantum yield (QY) of 69 and 42% was observed for crude org-FCNs, and crude P-CNDs; however after purification, QY of 1% and absence of one component from the fluorescent decays curve suggest the removal of fluorophores. Further, HR-TEM and DLS studies showed the quasi-spherical amorphous particles having < 10 nm particle size for P-CNDs. Besides, in vitro biocompatibility investigation and cellular uptake assay (1–100 μg/mL) against the MDA-MB 468 cell lines proves the ≥ 95% cell viability and good internalization for both org-FCNs and P-CNDs. Hence, our study shows the presence of fluorophore impurities in plant-derived CNDs, the removal and resemblance in biocompatibility properties. Hence, this information can be considered during the synthesis and isolation of CNDs. Simple and effective removal of impurities to harvest pure carbon nanodots (CNDs) through solvent-based selective separation method, and revelation of the cocktail flourphores similar to biocompatible blue fluorescent CNDs were studied.
With a strive to develop light-weight material for automotive and aerospace applications, aluminum-based hybrid nanocomposites (AHNCs) were manufactured utilizing the compocasting approach in this study. Chopped carbon fibers (CFs) are reinforced along with different weight fractions of nanoclay (1–5%) in the matrix of AA6026 forming AHNCs. The AHNCs specimens were examined by microstructural analysis, mechanical characterization, fatigue, and corrosion strength as per ASTM guidelines. Electroless plating method is adopted for coating CFs with copper to improve the wettability with matrix. SEM pictures of manufactured composites reveal thin inter-dendritic aluminum grains with precipitate particle of eutectic at intergranular junctions, as well as nanoclay particles that have precipitated in the matrix. Tensile strength (TS) rises with inclusion of nanoclay up to a maximum of 212.46 MPa for 3% nanoclay reinforcement, after which the TS is reduced due to non-homogeneity in distribution, agglomeration and de-bonding of nanoparticles. Similarly, micro-hardness increases with addition of 3% nanoclay after which it decreases. Higher energy absorption was achieved with 3% nanoclay reinforced hybrid and a significant improvement in flexural strength was obtained. With addition of both CFs and nanoclay, the fatigue strength of the hybrid composite tends to increase due to flexible CFs and high surface area nanoclays which strengthen the grain boundaries until 3% addition. Addition of nanoclay lowers the corrosion rate with nanoclays filling the crevices and voids in the matrix.
Southeast Asia is home to the Straits of Malacca and Singapore, one of the world’s most important sea lines of communication. The closure of the straits to international navigation may adversely affect the well-being of the global economy. On February 11, 2022, the Biden administration announced the new Indo-Pacific strategy, which will continue to deliver on AUKUS. For centuries, the proposed Thai Canal Project has been planned to revolutionize the shipping industry by bypassing the busy waters of the Straits of Malacca and Singapore. If the canal is built under the US Indo-Pacific Strategy, the pre-eminence of the Straits of Malacca and Singapore will not last long. This article analyzes the potential increase of navigation of nuclear-powered submarines through the Straits of Malacca and Singapore and its ensuing environmental implications from a viewpoint of international law. It discusses effects of the proposed canal plan in influencing the shipping industry should this “dream waterway” be constructed.
Lead sulfide ( PbS ) nanocrystals anchored on nitrogen-doped multiwalled carbon nanotubes ( CNx ) have been synthesized employing an environmentally friendly and inexpensive wet chemistry process. CNx∕PbS composites have been examined by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. Theorical ab initio calculations have been developed to determine the samples structural, morphological and optical properties to explain the experimental evidences. The PbS nanoparticles exhibit of 4 nm to 27 nm particle size with a face-centered cubic crystal structure and are homogeneously distributed along the carbon nanotubes. The nitrogen-doped CNTs acts as binding sites for the PbS clusters as ab initio theoretical study suggests.
The biocarbon (SKPH) was obtained from Sargassum spp., and it was evaluated electrochemically as support for the CO2 reduction. The biocarbon was synthesized and activated with KOH, obtaining a high surface area (1600 m2 g− 1) due to the activation process. Graphitic carbon formation after pyrolysis was confirmed by Raman spectroscopy. The XRD results show that SKPH has an amorphous structure with peaks corresponding to typical amorphous carbonaceous materials. FTIR was used to determine the chemical structure of SKPH. The bands at 3426, 2981, 2851, and 1604 cm− 1 correspond to O–H, C-H, and C-O stretching vibrations, respectively. Then, it compares SKPH films with different carbon films using two electrolytic systems with and without charge transfer. The SKPH film showed a capacitive behavior in the KOH, H2SO4, and, KCl systems; in the acid medium, the presence of a redox couple associated with carbon functional groups was shown. Likewise, in the [Fe(CN)6]−3 and Cu(II) systems, the charge transfer process coupled with a capacitive behavior was described, and this effect is more noticeable in the [Fe(CN)6]−3 system. Electrodeposition of copper on SKPH film showed two stages Cu(NH 3)2+ 4 /Cu(NH 3)+ 2 and Cu(NH 3)+ 2 ∕Cu in ammonia media. Hydrogen formation and the activity of CO2 are observed on SKPH film and are favored by the carbon’s surface chemistry. Cu/SKPH electrocatalyst has a catalytic effect on electrochemical reduction of CO2 and inhibition of hydrogen formation. This study showed that the SKPH film electrode responds as a capacitive material that can be used as an electrode for energy storage or as metal support.
The central theme of this work is the synthesis of single-walled carbon nanotubes (SWCNTs) through the chemical vapor deposition method (CVD). Single-walled carbon nanotubes are synthesized using catalyst-chemical vapor deposition of acetylene at 750 °C temperature. X-ray diffraction study gives a characteristic peak (002) at 26.55° corresponding to the existence of carbon nanotube confirms that the particles are crystalline in nature and hexagonal phase. An SEM and HRTEM outcome gives surface morphology of SWCNTs. The elemental composition was confirmed by EDAX. The ideal concentration of single-walled carbon nanotubes was used to design a novel electrochemical sensor for determining paracetamol (PA) using cyclic voltammetry. Electrochemical determination of paracetamol is described using a single-walled carbon nanotube modified carbon paste electrode (SWCNT/MCPE). The SWCNT/MCPE was used in this study to detect paracetamol electrochemically at pH 7.2 in a 0.2 M PBS with a scan rate of 50 mV s− 1. A single-walled nanotube modified carbon paste electrode was used to develop a sensitive and selective electrochemical technique for the detection of PA. The SWCNT/MCPE showed excellent electrocatalytic activity towards the oxidation of paracetamol in phosphate buffer solution. Therefore, with increased oxidation currents, the voltammetric responses of paracetamol at the bare carbon paste electrode are organized within cyclic voltammetric peaks.
The team has studied the relationship between the ability of the coals to be dissolved in crude anthracene oil and their composition. The coal samples taken from different deposits in Russia and Mongolia were characterized by different stages of metamorphism and tested by the Fourier transform infrared spectroscopy and Carbon-13 nuclear magnetic resonance. The data of a correlation analysis enabled us to find out that an amount of aromatic structures in coal macromolecules provided the main influence on the thermal dissolution of the coals. The middle-rank coals had the highest rates of coal organic matter transfer to liquid products. The data showed that the dissolution process was accompanied by destruction of weak bonds among aliphatic groups. The amount of methylene groups in the aliphatic part of coal macromolecules had a direct impact on conversion of the coal organic matter into soluble products.