Search Results (949)

This study developed a novel 3D-printable poly(vinylidene fluoride) (PVDF)-based nanocomposite incorporating 6 wt% graphene nanoplatelets (GNPs) with programmable characteristics for resistive heating applications. The results highlighted the significant effect of a controlled printing direction (longitudinal, diagonal, and transverse) on the electrical, thermal, Joule heating, and thermo-resistive properties of the printed structures. The 6 wt% GNP/PVDF nanocomposite exhibited a high electrical conductivity of 112 S·m⁻¹ when printed in a longitudinal direction, which decreased significantly in other directions. The Joule heating tests confirmed the material’s efficiency in resistive heating, with the maximum temperature reaching up to 65 °C under an applied low voltage of 2 V at a raster angle of printing of 0°, while the heating T_max decreased stepwise with 10 °C at the 45° and the 90° printing directions. The repeatability of the Joule heating performance was verified through multiple heating and cooling cycles, demonstrating consistent maximum temperatures across several tests. The effect of sample thickness, controlled by the number of printed layers, was investigated, and the results underscore the advantages of programmable 3D printing orientation in thin layers for enhanced thermal stability, tailored electrical conductivity, and efficient Joule heating capabilities of 6 wt% GNP/PVDF composites, positioning them as promising candidates for next-generation 3D-printed electronic devices and self-heating applications. Full article

Ti matrix composites (TMCs) are promising structural materials that meet the increasing demands for light weight the automobile and aircraft industries. However, the room temperature brittleness in the traditionally homogeneous reinforcement distribution of TMCs limits their application in high-strain-rate impact environments. In the present study, novel bilayer TMCs with hierarchical microstructures were designed by the laminated combination of graphene nanoplatelet (GNPs) reinforced TC4 (Ti-6Al-4V) composites (GNPs/TC4) and a monolithic TC4. Meanwhile, the configuration of the microstructure, impact performance V₅₀, and deformation modes of the bilayered TC4-(GNPs/TC4) plate was investigated. The plates were fabricated via field-assisted sintering technology (FAST). It turned out that the TC4-(GNPs/TC4) plate with a 7.5 mm thickness against a 7.62 mm projectile exhibited greater impact performance (V₅₀~825 m/s) compared to the TC4 and GNPs/TC4 single-layer plates. The plate failure modes were dependent on the microstructure while the failure behaviors seemed to be influenced by the hierarchical configuration. This work provided a new strategy for utilizing TMCs in the field of high-strain-rate impact environments. Full article

The investigation of new composite materials possessing low weight but not at the expense of their mechanical performance is of great interest in terms of reducing energy consumption in many industrial applications. This study is focused on the nanomechanical characterization of high-density polyethylene (HDPE)-based composite specimens modified with equal loadings of graphene nanoplatelets (GNPs) and/or multiwall carbon nanotubes (MWCNTs). Quasi-static nanoindentation analysis revealed the impact of the carbon nanofillers on the receiving of nanocomposites with higher nanohardness and reduced modulus of elasticity, reaching values of 0.146 GPa and 3.57 GPa, respectively. The role of the indentation size effect in elastic polymer matrix was assessed by applying three distinct peak forces. Nanoscratch experiments depicted the tribological behavior of the composite samples and inferred the influence of the carbon nanofillers on the values of the coefficient of friction (COF). It seems that the incorporation of 4 wt% GNPs in the polymer structure improves the scratch resistance of the material, resulting in a higher value of the exerted lateral force and therefore leading to the detection of a higher coefficient of friction at scratch of 0.401. A considerable pile-up response of the scratched polymer specimens was observed by means of in-situ SPM imaging of the tested surface sample area. The sway of the carbon nanoparticles on the composite pile-up behavior and the effect of the pile-up on the measured friction coefficients have been explored. Full article

Graphene oxide (GO) has recently gained significant attention in electrocatalysis as a promising electrode material owing to its unique physiochemical properties such as enhanced electron transfers due to a conjugated π-electron system, high surface area, and stable support for loading electroactive species, including metal nanoparticles. However, only a few studies have been directed toward the structural characteristics of GO, elaborating on the roles of oxygen-containing functional groups, the presence of defects, interlayer spacing between the layered structure, and nonuniformity in the carbon skeleton along with their influence on electrochemical performance. In this work, we aim to understand these properties in various GO materials derived from different graphitic sources. Both physiochemical and electrochemical characterization were employed to correlate the above-mentioned features and explore the effect of the location of the palladium nanoparticles (Pd NPs) on various GO supports for the hydrogen evolution reaction (HER). The interaction of the functional groups has a crucial role in the Pd dispersion and its electrochemical performance. Among the different GO samples, Pd supported on GO derived from graphene nanoplate (GNP), Pd/GO-GNP, exhibits superior HER performance; this could be attributed to the optimal balance among particle size, defect density, less in-plane functionalities, and higher electrochemical surface area. This study, thus, helps to identify the optimal conditions that lead to the best performance of Pd-loaded GO, contributing to the design of more effective HER electrocatalysts. Full article

Tylosin (TYL) is a macrolide antibiotic widely used in animal husbandry. Due to associated health risks, there is a demand for sensitive methods for mass screening of TYL in products of animal origin. This article describes the development of lateral flow immunoassays (LFIAs) for TYL detection using direct (anti-TYL antibodies conjugated with nanoparticles) and indirect antibody labeling (anti-species antibodies conjugated with nanoparticles and combined with native anti-TYL antibodies). The choice of LFIA conditions, such as concentrations of hapten–protein conjugates, specific antibodies, and gold nanoparticle (GNP) conjugates with antibodies, as well as incubation time of reagents and the concentration of detergent in the sample buffer, is presented. The achieved limits of TYL detection using LFIAs with indirect labeling were 0.8 ng/mL (visual) and 0.07 ng/mL (instrumental), compared to 4 ng/mL (visual) and 0.4 ng/mL (instrumental) for the case of direct labeling. The sensitivity of the LFIA using the indirect format was up to seven times higher, allowing the determination of the target analyte at low concentrations. TYL detection in ground meat using LFIA with indirect antibody labeling ranged from 76–119%. Full article

Background: Collectively, leishmaniasis and Chagas disease cause approximately 8 million cases and more than 40,000 deaths annually, mostly in tropical and subtropical regions. The current drugs used to treat these diseases have limitations and many undesirable side effects; hence, new drugs with better clinical profiles are needed. Fungal endophytes associated with plants are known to produce a wide array of bioactive secondary metabolites, including antiprotozoal compounds. In this study, we analyzed endophytic fungal isolates associated with Theobroma cacao and Coffea arabica crop plants, which yielded extracts with antitrypanosomatid activity. Methods: Crude extracts were subjected to bioassay-guided isolation by HPLC, followed by spectrometric and spectroscopic analyses via mass spectrometry (MS) and nuclear magnetic resonance (NMR), Results: Compounds 1–9 were isolated and displayed novel antitrypanosomal and antileishmanial activities ranging from 0.92 to 32 μM. Tandem liquid chromatography–mass spectrometry (LC–MS) analysis of the organic extracts from different strains via the feature-based Global Natural Products Social (GNPS) molecular networking platform allowed us to dereplicate a series of metabolites (10–23) in the extracts. Molecular docking simulations of the active compounds, using the 3-mercaptopyruvate sulfurtransferase protein from L. donovani (Ld3MST) and the cruzipain enzyme from T. cruzi as putative molecular targets, allowed us to suggest possible mechanisms for the action of these compounds. Conclusions: The isolation of these antiprotozoal compounds confirms that crop plants like coffee and cacao harbor populations of endophytes with biomedical potential that confer added value to these crops. Full article

Gliadin nanoparticle (GNP) is a promising foaming agent, but its application is hindered by the limited foam stability under low acidic conditions. Herein, we attempted to tune the foam stability of GNP by coating it with flaxseed gum (FG) and investigated the structure, interfacial behaviors, and foam functionality of gliadin-FG (GFG) particles at pH 4.5. Results showed that the formation of GFG complex particles was driven by an electrostatic interaction between positive charge patches on the surface of GNP (~17 mV) and negative charges in FG molecule (~−13 mV) at all tested ratios. The addition of appropriate amounts of FG (1:0.05) effectively improved the foam stability of GNP. This was because GFG with larger sizes and lower surface charge possessed higher rigidity after coating with FG. When they adsorbed at the air/water interface, their deformation process was slower than that of GNP, as indicated by interfacial dilatational rheology and cryo-SEM, and the covered particles seemed to be more closely distributed to form solid-like and dense interfacial films. Notably, the addition of FG at a higher ratio (1:0.3) promoted the foam stability of GNP by about five folds because the larger GFG with suitable flexibility and wettability could form a stiff interface layer with more significant elastic response, and the unabsorbed particles and FG could form a gel-like network structure in the continuous phase. These characteristics effectively prevented foam disproportionation and coalescence, as well as retard the drainage. Our findings demonstrate that coating GNPs with FG is an effective approach to improve their application in foamed foods. Full article

An investigation of ×19 soil samples collected under the auspices of the Australian citizen science initiative, Soils for Science, returned ×559 chemically dereplicated microbial isolates, of which ×54 exhibited noteworthy anthelmintic activity against either the heartworm Dirofilaria immitis microfilaria and/or the gastrointestinal parasite Haemonchus contortus L1–L3 larvae. Chemical (GNPS and UPLC-DAD) and cultivation (MATRIX) profiling prompted a detailed chemical investigation of Streptomyces sp. S4S-00196A10, which yielded new anthelmintic polyketide goondapyrones A–J (1–10), together with the known actinopyrones A (11) and C (12). Structures for 1–12 were assigned on the basis of detailed spectroscopic and chemical analysis, with preliminary structure activity relationship analysis revealing selected γ-pyrones >50-fold and >13-fold more potent than isomeric α-pyrones against D. immitis mf motility (e.g., EC₅₀ 0.05 μM for 1; EC₅₀ 2.7 μM for 5) and H. contortus L1–L3 larvae development (e.g., EC₅₀ 0.58 μM for 1; EC₅₀ 8.2 μM for 5), respectively. Full article

Currently, clinically available cancer chemopreventive drug options are limited to mostly tamoxifen and its derivatives, such as raloxifene, and approved specifically for breast cancer. Thus, the availability of chemopreventive drug molecules for other types of malignant cancers would be desirable. In previous reports, the arils of Myristica fragrans (mace) have been found to exhibit cancer chemopreventive activity. Therefore, the purpose of the present study was to identify a natural product from this species with potential chemopreventive activity guided by chemoinformatic sample analysis via Global Natural Products Social (GNPS) molecular networking and molecular docking. The neolignan licarin A (1) was identified as a potential chemopreventive constituent, and subsequently submitted to several in vitro bioassays and a zebrafish toxicity evaluation. In this work, 1 afforded superior phosphoNF-κBp65 phosphorylation activity in DU-145 prostate cancer cells compared to isoliquiritigenin (2), which was used as a natural product chemopreventive control. Both 1 and 2 showed a longer-lasting reduction in cellular stress in a cell oxidative stress real-time dose–response assay than the positive control using Hepa1c1c7 mouse hepatoma cells. In addition, 1 displayed similar activities to 2, while also being less toxic to zebrafish (Danio rerio) than both this chalcone and the clinically used chemopreventive drug tamoxifen. Full article

Scrophulariae Radix (SR), the dried root of Scrophularia ningpoensis Hemsl (S. ningpoensis), has been extensively used as traditional Chinese medicine for thousands of years. However, since the mid-20th century, the traditional processing technology of S. ningpoensis has been interrupted. Therefore, ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry technology, together with a Global Natural Product Social Molecular Networking (GNPS) method, was applied to comprehensively analyze the characteristic changes and mutual transformation of chemical constituents in the differently processed roots of S. ningpoensis, as well as to scientifically elucidate the processing mechanism of differently processed SR. As a result, a total of 149 components were identified. Notably, with the help of the GNPS data platform and MS² fragment ions, the possible structures of four new compounds (47, 48, 50, and 73) were deduced in differently processed SR samples, in which 47, 48, and 50 are iridoid glycosides, and 73 is a phenylpropanoid glycoside. Five cyclopeptides (78, 86, 97, 99, and 104) derived from leucine (isoleucine) were identified in SR for the first time. The heatmaps analysis results indicated that leucine or isoleucine may be converted to cyclopeptides under the prolonged high-temperature conditions. Moreover, it is found that short-time steaming can effectively prevent the degradation of glycosides by inactivating enzymes. This study provides a new and efficient technical strategy for systematically identifying the chemical components, rapidly discovering the components, and preliminarily clarifying the processing mechanism of S. ningpoensis, as well as also providing a scientific basis for the improvement of the quality standards and field processing of S. ningpoensis. Full article

Silene viscidula Franch is mainly produced in southwest China. The region has a vast area and rich climate, which has an impact on the quality of the plants due to the differences in distribution between the origins. There is a lack of systematic research on its chemical compounds in the existing literature, and fewer studies have been reported for the active compounds of this plant. Therefore, high-resolution liquid mass spectrometry was used in this study. Sixty batches of Silene viscidula Franch samples from twenty origins in three provinces were analyzed for compounds. A database of chemical compounds of Silene viscidula Franch was established through node-to-node information in the GNPS molecular network, as well as literature records. The ion fragmentation information obtained was compared with the literature data and analyzed and identified by importing the mass spectrometry software PeakView 1.2. Then, the MarkerView t-test was applied to analyze and identify the compounds of Silene viscidula Franch from different origins. Afterwards, the antioxidant activity of Silene viscidula Franch from different origins was preliminarily evaluated using DPPH and ABTS free radical scavenging assays. The results showed a total of 78 compounds, including 34 steroids, 14 triterpenoid saponins, 30 flavonoid glycosides, and other classes of compounds, such as alkaloids. The cleavage patterns of steroids, triterpenoid saponins, and flavonoids in positive-ion mode were also summarized. Based on the p-value of the t-test (p < 0.05), 29 differential compounds were screened out. The relative contents of saponins and steroidal compounds in these samples were found to be associated with antioxidant activity. This study provided a preliminary reference for the establishment of a comprehensive evaluation system for the quality of Silene viscidula Franch. Full article

Cyano-functionalized graphitic nanoplatelets (CyGNs) are synthesized by means of a mechanochemical reaction between graphite and acrylonitrile. The resulting CyGNs exhibit excellent mechanical properties and are highly dispersible in various solvents (i.e., THF). Due to their chemical compatibility (specifically, cyano functional groups), the CyGNs serve effectively as a reinforcing filler for acrylonitrile butadiene styrene (ABS) resin. Consequently, compared to pure ABS, CyGN&ABS-X demonstrates improved mechanical properties and better thermal stability. Notably, the CyGN&ABS-1 specimen exhibits significant enhancements in the tensile strength (26 ± 1 MPa), Young’s modulus (992 ± 71 MPa), and tensile toughness (22 ± 3 MPa), representing increases of approximately 130.6%, 19.2%, and 59.6%, respectively, over pure ABS. This underscores the ability of a mechanochemical reaction to directly modify the functional groups of graphitic nanoplatelets (GnPs) as fillers, facilitating their strong compatibility with a variety of polymers, including copolymers. Full article

The growing importance of electromagnetic interference (EMI) shielding composites in civil engineering has garnered increasing attention. Conductive cement-based composites, incorporating various conductive fillers, such as carbon nanotubes (CNTs), carbon fibers (CFs), and graphene nanoplatelets (GNPs), provide effective solutions due to their high electrical conductivity. While previous studies have primarily focused on improving the overall shielding effectiveness, this research emphasizes balancing the reflection and absorption properties. The experimental results demonstrate an EMI shielding performance exceeding 50 dB, revealing that filler size (nano, micro, or macro) and shape (platelet or fiber) significantly influence both reflection and absorption characteristics. Based on a comprehensive evaluation of the shielding properties, this study highlights the need to consider factors such as reflection versus absorption losses and filler shape or type when optimizing filler content to develop effective cement-based EMI shielding composites. Full article

The sintering process of Cu nanoparticle (Cu NP)/graphene nanoplatelet (GNP) composite solder paste was thoroughly investigated in this work through molecular dynamics simulations. The tensile properties of the sintered Cu NP/GNP composite solder paste were considered by using the uniaxial quasi-static tensile simulation method. The impact of sintering temperature, strain rate, and GNP addition on the tensile properties of Cu NP/GNP sintered structures was thoroughly investigated. The lattice structure, dislocation evolution, and atomic diffusion of the molecular dynamics results were analyzed using the common neighbor analysis (CNA), dislocation extraction algorithm (DXA), and mean square displacement (MSD) methods. The results of the post-processing analysis showed that the addition of GNP and the sintering temperature have an important influence on the mechanical properties of Cu NP/GNP sintered structures. In addition, the incorporation of GNP can significantly improve the mechanical properties of sintered Cu NP/GNP composite solder paste. More specifically, the tensile strength and fracture strain of the sintered composite solder paste will be increased by increasing the tensile strain rate. The strengthening mechanism of the sintered Cu NP/GNP composite solder paste can be attributed to the dislocation strengthening mechanism. Our study provides valuable insight for the development of high-performance composite solder paste with enhanced mechanical properties. Full article

Background/Objectives: Recently, antimicrobial-resistant pathogens and cancers have emerged as serious global health problems, highlighting the immediate need for novel therapeutics. Consequently, we aimed to isolate and characterize endophytic Streptomyces strains from the rhizospheres of the Himalayan region of Nepal and identify specialized metabolites with antibacterial, antifungal, and cytotoxic potential. Methods: To isolate Streptomyces sp., we collected two soil samples and cultured them on an ISP4 medium after pretreatment. We isolated and identified the strains PY108 and PY109 using a combination of morphological observations and 16S rRNA gene sequencing. Results: The BLAST results showed that PY108 and PY109 resembled Streptomyces hundungensis PSB170 and Streptomyces sp. Ed-065 with 99.28% and 99.36% nucleotide similarity, respectively. Antibacterial assays of ethyl acetate (EA) extracts from both isolates PY108 and PY109 in a tryptic soy broth (TSB) medium were conducted against four pathogenic bacteria. They showed significant antibacterial potential against Staphylococcus aureus and Klebsiella pneumoniae. Similarly, these extracts exhibited moderate antifungal activities against Saccharomyces cerevisiae and Aspergillus niger. Cytotoxicity assays on cervical cancer cells (HeLa) and breast cancer cells (MCF-7) revealed significant potential for both extracts. LC-MS/MS profiling of the EA extracts identified 27 specialized metabolites, including diketopiperazine derivatives, aureolic acid derivatives such as chromomycin A, and lipopeptide derivatives. In comparison, GC-MS analysis detected 34 metabolites, including actinomycin D and γ-sitosterol. Furthermore, a global natural product social molecular networking (GNPS)-based molecular networking analysis dereplicated 24 metabolites in both extracts. Conclusions: These findings underscore the potential of endophytic Streptomyces sp. PY108 and PY109 to develop new therapeutics in the future. Full article