The Effect of Coupling Agents and Graphene on the Mechanical Properties of Film-Based Post-Consumer Recycled Plastic.

This study aims to improve the mechanical properties of post-consumer recycled (PCR) plastic composed primarily of polypropylene (PP) and polyethylene (PE), which generally exhibit poor miscibility, by applying coupling agents and graphene. Here, we compare a commercially available coupling agent with a directly synthesized maleic anhydride (MA) coupling agent. When applied to a 5:5 blend of recycled PP and PE, an optimum tensile strength was achieved at a 3 wt% coupling agent concentration, with the MA coupling agent outperforming the commercial one. Characterization through Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry analysis (TGA) revealed a PP:PE ratio of approximately 3:7 in the PCR plastics, with 4.86% heterogeneous materials present. Applying 3 wt% of the commercial and MA coupling agents to the PCR plastics resulted in a significant 53.9% increase in the tensile strength, reaching 11.25 MPa, and a remarkable 421.54% increase in the melt flow index (MFI), reaching 25.66 g/10 min. Furthermore, incorporating 5 wt% graphene led to a notable 64.84% increase in the tensile strength. In addition, the application of MA coupling agents and graphene improved the thermal stability of the PCR plastics. These findings show significant promise for addressing environmental concerns associated with plastic waste by facilitating the recycling of PCR plastics into new products. The utilization of coupling agents and graphene offers a viable approach to enhance the mechanical properties of PCR plastics, paving the way for sustainable and environmentally friendly solutions.

Pentagons and Heptagons on Edges of Graphene Nanoflakes Analyzed by X-ray Photoelectron and Raman Spectroscopy.

Identifying pentagons and heptagons in graphene nanoflake (GNF) structures at the atomic scale is important to completely understand the chemical and physical properties of these materials. Herein, we used X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy to analyze the spectral features of GNFs according to the position of pentagons and heptagons introduced onto their zigzag and armchair edges. The XPS peak maxima were shifted to higher binding energies by introducing the pentagons or heptagons on armchair rather than zigzag edges, and the structures could be distinguished depending on the positions of the introduced pentagons or heptagons. Raman spectroscopic analyses also revealed that the position of edges with introduced pentagons or heptagons could also be identified using Raman spectroscopy, with characteristic bands appearing at 800-1200 cm-1, following the introduction of either pentagons or heptagons on armchair edges. This precise spectroscopic identification of pentagons and heptagons in GNFs provides the groundwork for the analysis of graphene-related materials.

Analysis of Shape Memory Behavior and Mechanical Properties of Shape Memory Polymer Composites Using Thermal Conductive Fillers.

Shape memory polymers (SMPs) are attracting attention for their use in wearable displays and biomedical materials due to their good biocompatibility and excellent moldability. SMPs also have the advantage of being lightweight with excellent shape recovery due to their low density. However, they have not yet been applied to a wide range of engineering fields because of their inferior physical properties as compared to those of shape memory alloys (SMAs). In this study, we attempt to find optimized shape memory polymer composites. We also investigate the shape memory performance and physical properties according to the filler type and amount of hardener. The shape memory composite was manufactured by adding nanocarbon materials of graphite and non-carbon additives of Cu. The shape-recovery mechanism was compared, according to the type and content of the filler. The shape fixation and recovery properties were analyzed, and the physical properties of the shape recovery composite were obtained through mechanical strength, thermal conductivity and differential scanning calorimetry analysis.

Poly(vinylalcohol) (PVA) Assisted Sol-Gel Fabrication of Porous Carbon Network-Na3V2(PO4)3 (NVP) Composites Cathode for Enhanced Kinetics in Sodium Ion Batteries.

Na3V2(PO4)3 is regarded as one of the promising cathode materials for next-generation sodium ion batteries, but its undesirable electrochemical performances due to inherently low electrical conductivity have limited its direct use for applications. Motivated by the limit, this study employed a porous carbon network to obtain a porous carbon network-Na3V2(PO4)3 composite by using poly(vinylalcohol) assised sol-gel method. Compared with the typical carbon-coating approach, the formation of a porous carbon network ensured short ion diffusion distances, percolating electrolytes by distributing nanosized Na3V2(PO4)3 particles in the porous carbon network and suppressing the particle aggregation. As a result, the porous carbon network-Na3V2(PO4)3 composite exhibited improved electrochemical performances, i.e., a higher specific discharge capacity (~110 mAh g-1 at 0.1 C), outstanding kinetic properties (~68 mAh g-1 at 50 C), and stable cyclic stability (capacity retention of 99% over 100 cycles at 1 C).

Sensitive detection of influenza a virus based on a CdSe/CdS/ZnS quantum dot-linked rapid fluorescent immunochromatographic test.

Prevention is the most effective management strategy for influenza A infection in humans. In this study, we developed a CdSe/CdS/ZnS quantum dot (QD) fluorescent dye for rapid and sensitive detection of two common subtypes (H1N1 and H3N2) of influenza A virus, and examined its utility. CdSe/CdS/ZnS QD was conjugated with antibody (Ab) after conjugation with latex, making QD conjugate of QD + Latex + Ab. A stable photoluminescence of QD conjugate and advantage of CdSe/CdS/ZnS QD used was characterized in this study. The performance of a rapid fluorescent immunochromatographic test (FICT) employing QD conjugate (QD-FICT) in detecting influenza A/H1N1 was 8-fold and 64-fold higher than that of a europium nanoparticle-based FICT and a rapid diagnostic test (RDT; Standard Diagnostics BIOLINE Influenza A/B), respectively. For influenza A/H3N2, QD-FICT showed 8-fold and 128-fold higher performance than europium nanoparticle-based FICT and RDT, respectively. In clinical evaluations, QD-FICT showed 93.75% clinical sensitivity [45/48; 95% confidence interval (95% CI): 82.80-98.69], 100% clinical specificity (117/117; 95% CI: 96.90-100.00), and strong correlation (kappa; 0.98) with rRT-PCR (20 ≤ Ct ≤ 40). Europium nanoparticle-linked FICT showed 79.17% clinical sensitivity (38/48; 95% CI: 65.01-89.53) and 100% clinical specificity (117/117; 95% CI: 96.90-100.00), whereas RDT showed 77.08% sensitivity (37/48; 95% CI: 62.69-87.97), 100% specificity (117/117; 95% CI: 96.90-100.00), and reasonably good correlation with rRT-PCR (kappa; 0.93). Water-soluble QDs can therefore be used as an effective material for developing fluorescent diagnostic systems for rapid detection of human influenza A virus in clinical specimens.

Development of a Rapid Fluorescent Immunochromatographic Test to Detect Respiratory Syncytial Virus.

Human respiratory syncytial virus (RSV) is one of the most common viruses infecting the respiratory tracts of infants. The rapid and sensitive detection of RSV is important to minimize the incidence of infection. In this study, novel monoclonal antibodies (mAbs; B11A5 and E8A11) against RSV nucleoprotein (NP) were developed and applied to develop a rapid fluorescent immunochromatographic strip test (FICT), employing europium nanoparticles as the fluorescent material. For the FICT, the limits of detection of the antigen and virus were 1.25 µg/mL and 4.23 × 106 TCID50/mL, respectively, corresponding to 4.75 × 106 ± 5.8 ×105 (mean ± SD) RNA copy numbers per reaction mixture for RSV NP. A clinical study revealed a sensitivity of 90% (18/20) and specificity of 98.18% (108/110) for RSV detection when comparing the performance to that of reverse transcription polymerase chain reaction (RT-PCR), representing a 15% improvement in sensitivity over the SD Bioline rapid kit. This newly developed FICT could be a useful tool for the rapid diagnosis of RSV infection.

Vertical Si nanowire arrays fabricated by magnetically guided metal-assisted chemical etching.

In this work, vertically aligned Si nanowire arrays were fabricated by magnetically guided metal-assisted directional chemical etching. Using an anodized aluminum oxide template as a shadow mask, nanoscale Ni dot arrays were fabricated on an Si wafer to serve as a mask to protect the Si during the etching. For the magnetically guided chemical etching, we deposited a tri-layer metal catalyst (Au/Fe/Au) in a Swiss-cheese configuration and etched the sample under the magnetic field to improve the directionality of the Si nanowire etching and increase the etching rate along the vertical direction. After the etching, the nanowires were dried with minimal surface-tension-induced aggregation by utilizing a supercritical CO2 drying procedure. High-resolution transmission electron microscopy (HR-TEM) analysis confirmed the formation of single-crystal Si nanowires. The method developed here for producing vertically aligned Si nanowire arrays could find a wide range of applications in electrochemical and electronic devices.

Enhanced Power Conversion Efficiency of Graphene/Silicon Heterojunction Solar Cells Through NiO Induced Doping.

We report a doping strategy, where nickel oxide (NiO) nanoparticle film coating is employed for graphene/Si heterojunction solar cells to improve the power conversion efficiency (PCE). NiO doping has been shown to improve the short circuit current (J(SC)) by 12%, open circuit voltage (V(OC)) by 25% and fill factor (FF) by 145% of the cells, in turn increasing the PCE from 1.37% to 4.91%. Furthermore, NiO doped graphene/Si solar cells don't show any significant performance degradation over 10 days revealing that NiO doping can be a promising approach for practical applications of graphene in solar cells.

Highly specific SNP detection using 2D graphene electronics and DNA strand displacement.

Single-nucleotide polymorphisms (SNPs) in a gene sequence are markers for a variety of human diseases. Detection of SNPs with high specificity and sensitivity is essential for effective practical implementation of personalized medicine. Current DNA sequencing, including SNP detection, primarily uses enzyme-based methods or fluorophore-labeled assays that are time-consuming, need laboratory-scale settings, and are expensive. Previously reported electrical charge-based SNP detectors have insufficient specificity and accuracy, limiting their effectiveness. Here, we demonstrate the use of a DNA strand displacement-based probe on a graphene field effect transistor (FET) for high-specificity, single-nucleotide mismatch detection. The single mismatch was detected by measuring strand displacement-induced resistance (and hence current) change and Dirac point shift in a graphene FET. SNP detection in large double-helix DNA strands (e.g., 47 nt) minimize false-positive results. Our electrical sensor-based SNP detection technology, without labeling and without apparent cross-hybridization artifacts, would allow fast, sensitive, and portable SNP detection with single-nucleotide resolution. The technology will have a wide range of applications in digital and implantable biosensors and high-throughput DNA genotyping, with transformative implications for personalized medicine.

High-performance flexible hydrogen sensor made of WS2 nanosheet-Pd nanoparticle composite film.

We report a flexible hydrogen sensor, composed of WS2 nanosheet-Pd nanoparticle composite film, fabricated on a flexible polyimide substrate. The sensor offers the advantages of light-weight, mechanical durability, room temperature operation, and high sensitivity. The WS2-Pd composite film exhibits sensitivity (R 1/R 2, the ratio of the initial resistance to final resistance of the sensor) of 7.8 to 50,000 ppm hydrogen. Moreover, the WS2-Pd composite film distinctly outperforms the graphene-Pd composite, whose sensitivity is only 1.14. Furthermore, the ease of fabrication holds great potential for scalable and low-cost manufacturing of hydrogen sensors.

Palladium Decorated Graphene-Nanoribbon Network for Enhanced Gas Sensing.

The fabrication of large-scale graphene nanoribbon (GNR) network and its application for gas sensing are reported. A large area, nanoscale GNR network was produced by a facile approach of silver nanowires (Ag NWs) templated graphene masking and subsequent 02 plasma etching. GNR network shows significantly enhanced sensitivity to ammonia gas compared to pristine graphene layer. The gas detection sensitivity of the nanoscale GNR network is even further improved by decorating GNR network with palladium (Pd) or platinum (Pt) nanoparticles, which show a relative resistance response of 65% and 45%, respectively to 50 ppm (parts per million) of ammonia (NH3) in nitrogen (N2) at room temperature as well as good reversibility in air.

Uniformly Nanopatterned Graphene Field-Effect Transistors with Enhanced Properties.

We have successfully fabricated and characterized highly uniform nanopatterned graphene (NPG). Thin anodized aluminum oxide nanomask was prepared by facile self-assembly technique without using polymer buffer layer, which was utilized as a direct-contact template for oxygen plasma etch to produce near-periodic, small-neck-width NPG. The NPG exhibits a homogeneous mesh structure with an average neck width as small as ~11 nm. The highly uniform 11-nm neck width creates a quantum confinement in NPG, which has led to a record bandgap opening of ~200 meV in graphene for the given level of neck width. Electronic characterization of single-layer NPG field-effect transistors (FETs) was performed, which demonstrated a high on-off switching ratio. We found that the NPG allows for experimental confirmation of the relationship between electrical conductance and bandgap. This work also demonstrates that our direct-contact, self-assembled mask lithography is a pathway for low-cost, high-throughput, large-scale nanomanufacturing of graphene nanodevices.

Unusually High Optical Transparency in Hexagonal Nanopatterned Graphene with Enhanced Conductivity by Chemical Doping.

Graphene has received appreciable attention for its potential applications in flexible conducting film due to its exceptional optical, mechanical, and electrical properties. However increasing transmittance of graphene without sacrificing the electrical conductivity has been difficult. The fabrication of optically highly transparent (≈98%) graphene layer with a reasonable electrical conductivity is demonstrated here by nanopatterning and doping. Anodized aluminium oxide nanomask prepared by facile and simple self-assembly technique is utilized to produce an essentially hexagonally nanopatterned graphene. The electrical resistance of the graphene increases significantly by a factor of ≈15 by removal of substantial graphene regions via nanopatterning into hexagonal array pores. However, the use of chemical doping on the nanopatterned graphene almost completely recovers the lost electrical conductivity, thus leading to a desirably much more optically transparent conductor having ≈6.9 times reduced light blockage by graphene material without much loss of electrical conductivity. It is likely that the availability of large number of edges created in the nanopatterned graphene provides ideal sites for chemical dopant attachment, leading to a significant reduction of the sheet resistance. The results indicate that the nanopatterned graphene approach can be a promising route for simultaneously tuning the optical and electrical properties of graphene to make it more light-transmissible and suitable as a flexible transparent conductor.

MoS2 Nanosheet-Pd Nanoparticle Composite for Highly Sensitive Room Temperature Detection of Hydrogen.

Highly sensitive hydrogen detection at room temperature can be realized by employing solution-processed MoS2 nanosheet-Pd nanoparticle composite. A MoS2-Pd composite exhibits greater sensing performance than its graphene counterpart, indicating that solvent exfoliated MoS2 holds great promise for inexpensive and scalable fabrication of highly sensitive chemical sensors.

Rapid and quantitative detection of zoonotic influenza A virus infection utilizing coumarin-derived dendrimer-based fluorescent immunochromatographic strip test (FICT).

Great efforts have been made to develop robust signal-generating fluorescence materials which will help in improving the rapid diagnostic test (RDT) in terms of sensitivity and quantification. In this study, we developed coumarin-derived dendrimer-based fluorescent immunochromatographic strip test (FICT) assay with enhanced sensitivity as a quantitative diagnostic tool in typical RDT environments. The accuracy of the proposed FICT was compared with that of dot blot immunoassay techniques and conventional RDTs. Through conjugation of coumarin-derived dendrimers with latex beads, fluorescent emission covering broad output spectral ranges was obtained which provided a distinct advantage of easy discrimination of the fluorescent emission of the latex beads with a simple insertion of a long-pass optical filter away from the excitation wavelength. The newly developed FICT assay was able to detect 100 ng/10 µL of influenza A nucleoprotein (NP) antigen within 5 minutes, which corresponded to 2.5-fold higher sensitivity than that of the dot blot immunoassay or conventional RDTs. Moreover, the FICT assay was confirmed to detect at least four avian influenza A subtypes (H5N3, H7N1, H7N7, and H9N2). On applying the FICT to the clinical swab samples infected with respiratory viruses, our FICT assay was confirmed to differentiate influenza H1N1 infection from other respiratory viral diseases. These data demonstrate that the proposed FICT assay is able to detect zoonotic influenza A viruses with a high sensitivity, and it enables the quantitation of the infection intensity by providing the numerical diagnostic values; thus demonstrating enhanced detectability of influenza A viruses.

Ethyl gallate induces apoptosis of HL-60 cells by promoting the expression of caspases-8, -9, -3, apoptosis-inducing factor and endonuclease G.

Many phytochemicals have been recognized to have potential therapeutic efficacy in cancer treatment. In this study, we investigated ethyl gallate (EG) for possible proapoptotic effects in the human promyelocytic leukemia cell line, HL-60. We examined cell viability, morphological changes, DNA content and fragmentation, and expression of apoptosis-related proteins for up to 48 h after EG treatment. The results showed that EG induced morphological changes and DNA fragmentation and reduced HL-60 cell viability in a dose-dependent and time-dependent manner. Western blotting analysis indicated that EG-mediated HL-60 apoptosis mainly occurred through the mitochondrial pathway, as shown by the release of cytochrome c, apoptosis-inducing factor (AIF), and endonuclease G (Endo G), as well as the upregulation of Bcl-2-associated X protein (Bax). EG also activated the death receptor-dependent pathway of apoptosis by enhancing the expression of caspases-8, -9, and -3 and the Bcl-2 interacting domain (Bid). Collectively, our results showed that EG induces apoptosis in HL-60 via mitochondrial-mediated pathways.

Protective effects of the ethanolic extract of Melia toosendan fruit against colon cancer.

Colorectal cancer is one of the leading causes of death in the world. Plant-derived products have proven to be valuable sources for discovery and development of unique anticancer drugs. In this study, the inhibitory effects of ethanolic extract of Melia toosendan fruit (EMTF), a traditional medicine in the Chinese Pharmacopeia were evaluated in vitro and in vivo against colon cancer. Human colon cancer cells SW480 and murine colorectal adenocarcinoma cells CT26 were used to investigate cell proliferation. The results showed that EMTF inhibited cell proliferation of SW480 and CT26 by promoting apoptosis as indicated by nuclear chromatin condensation and DNA fragmentation. Through increasing mitochondrial membrane permeability and cytochrome c release from mitochondria, EMTF induced caspase-9 activity which further activated caspase-3 and poly(ADP-ribose) polymerase cleavage, leading the tumor cells to apoptosis. The in vivo results confirmed reduction of tumor volume and apoptotic effects and the side effects were not induced by EMTF. Therefore, EMTF may be an effective chemotherapeutic agent for colon cancer treatment.

Asiatic acid induces colon cancer cell growth inhibition and apoptosis through mitochondrial death cascade.

Cancer is one of the leading causes of death in the world. The triterpenoid compound asiatic acid derived from the tropical medicinal plant Centella asiatica displays cytotoxic activity on fibroblast cells and several other kinds of cells. The present work studies asiatic acid-mediated growth inhibition of cancer cells and the underlying mechanism. Asiatic acid markedly inhibited cancer cell proliferation. Apoptosis of SW480 human colon cancer cells was induced by asiatic acid as shown by flow cytometry, DNA fragmentation and nuclear chromatin condensation experiments. Through increasing mitochondrial membrane permeability and cytochrome c release from mitochondria into cytosol, asiatic acid induced caspase-9 activity, which further activated caspase-3 and poly(ADP-ribose) polymerase cleavage resulting in irreversible apoptotic death in the tumor cells. Taken together, these results suggest that mitochondrial death apoptosis cascade plays very important roles in asiatic acid-induced cancer apoptosis.

An infantile case of Sturge-Weber syndrome in association with Klippel-Trenaunay-Weber syndrome and phakomatosis pigmentovascularis.

Sturge-Weber syndrome can be associated with facial port-wine stains and intracranial calcification, and concurrent Klippel-Trenaunay-Weber syndrome has been reported. Klippel-Trenaunay-Weber syndrome is a rare congenital mesodermal phakomatosis characterized by cutaneous hemangiomas, venous varicosities and soft tissue or bone hypertrophy of the affected extremities. This report is presented a rare case of the Sturge-Weber syndrome in combination with the Klippel-Trennaunay syndrome and phakomatosis pigmentovascularis in a 4-month-old infant. He showed nevus flameus on the right leg and both part of the face and back, leptomeningeal angiomatosis on right hemisphere, hypertrophy of the right leg, hemiconvulsion on the left and also evidences of congenital glaucoma and nevus of Ota. Very rare case combined with these three kinds of phakomatosis has been reported.