Wide bandgap semiconductor nanomembranes as a long-term biointerface for flexible, implanted neuromodulator.

Electrical neuron stimulation holds promise for treating chronic neurological disorders, including spinal cord injury, epilepsy, and Parkinson's disease. The implementation of ultrathin, flexible electrodes that can offer noninvasive attachment to soft neural tissues is a breakthrough for timely, continuous, programable, and spatial stimulations. With strict flexibility requirements in neural implanted stimulations, the use of conventional thick and bulky packages is no longer applicable, posing major technical issues such as short device lifetime and long-term stability. We introduce herein a concept of long-lived flexible neural electrodes using silicon carbide (SiC) nanomembranes as a faradic interface and thermal oxide thin films as an electrical barrier layer. The SiC nanomembranes were developed using a chemical vapor deposition (CVD) process at the wafer level, and thermal oxide was grown using a high-quality wet oxidation technique. The proposed material developments are highly scalable and compatible with MEMS technologies, facilitating the mass production of long-lived implanted bioelectrodes. Our experimental results showed excellent stability of the SiC/silicon dioxide (SiO2) bioelectronic system that can potentially last for several decades with well-maintained electronic properties in biofluid environments. We demonstrated the capability of the proposed material system for peripheral nerve stimulation in an animal model, showing muscle contraction responses comparable to those of a standard non-implanted nerve stimulation device. The design concept, scalable fabrication approach, and multimodal functionalities of SiC/SiO2 flexible electronics offer an exciting possibility for fundamental neuroscience studies, as well as for neural stimulation-based therapies.

Unravelling performance of honeycomb structures as drug delivery systems for the isoniazid drug using DFT-D3 correction dispersion and molecular dynamic simulations.

In this study, the potential of aluminum nitride (h-AlN), boron nitride (h-BN) and silicon carbide (h-SiC) nanosheets as the drug delivery systems (DDS) of isoniazid (INH) was scrutinized through density functional theory (DFT) and molecular dynamic (MD) simulations. We performed DFT periodic calculations on the geometry and electronic features of nanosheets adsorbed with INH by the DFT functional (DZP/GGA-PBE) employed in the SIESTA code. In the energetically favorable model, an oxygen atom of the C-O group of the INH molecule interacts with a Si atom of the h-SiC at 2.077 Å with an interaction energy of -1.361 eV. Charge transfer (CT) calculation by employing the Mulliken, Hirshfeld and Voronoi approaches reveals that the monolayers and drug molecules act as donors and acceptors, respectively. The density of states (DOS) calculations indicate that the HOMO-LUMO energy gap (HLG) of the h-SiC nanosheet declines significantly from 2.543 to 1.492 eV upon the adsorption of the INH molecule, which causes an electrical conductivity increase and then produces an electrical signal. The signal is linked to the existence of INH, demonstrating that h-SiC may be an appropriate sensor for INH sensing. The decrease in HLG for the interaction of INH and h-SiC is the uppermost (up to 41%) representing the uppermost sensitivity, whereas the sensitivity trend is σ(h-SiC) > σ(h-AlN) > σ(h-BN). Quantum theory of atoms in molecules (QTAIM) investigations is employed to scrutinize the nature of the INH/nanosheet interactions. The QTAIM analysis reveals that the interaction of the INH molecule and h-SiC has a partially covalent nature, while INH/h-AlN model electrostatic interaction occurs in the system and noncovalent and electrostatic interaction for the INH/h-BN model. Finally, the state-of-the-art DFT-MD simulations utilized in this study can mimic ambient conditions. The results obtained from the MD simulation show that it takes more time to bond the INH drug and h-SiC, and the INH/h-SiC system becomes stable. The results of the current research demonstrate the potential of h-SiC as a suitable sensor and drug delivery platform for INH drugs to remedy tuberculosis.

Salivary, acidic and enzymatic degradation of resin composite subjected to different finishing and polishing systems.

PURPOSE: To evaluate the effect of different finishing and polishing systems on the surface roughness of a resin composite subjected to simulated saliva-, acid-, and enzyme-induced degradation. METHODS: 160 specimens (n= 40) were fabricated with Filtek Z350 XT nanofilled composite and analyzed for average surface roughness (Ra). The specimens were finished and polished using: AD - Al2O3-impreginated rubberized discs (medium, fine, and superfine grit, Sof-Lex); SD - silicon carbide and Al2O3-impregnated rubberized discs (coarse, medium and fine grit, Jiffy,); MB - 12- and 30-multiblade burs. The control group (CT) (n= 40) comprised specimens with a Mylar-strip-created surface. Specimens from each group were immersed in 1 mL of one of the degradation methods (n= 10): artificial saliva (ArS: pH 6.75), cariogenic challenge (CaC: pH 4.3), erosive challenge (ErC: 0.05M citric acid, pH 2.3) or enzymatic challenge (EzC: artificial saliva with 700 µg/mL of albumin, pH 6.75). The immersion period simulated a time frame of 180 days. Ra measurements were also performed at the post-polishing and post-degradation time points. The data were evaluated by three-way ANOVA for repeated measures and the Tukey tests. RESULTS: There was significant interaction between the finishing/polishing system and the degradation method (P= 0.001). AD presented the greatest smoothness, followed by SD. After degradation, CT, AD and SD groups became significantly rougher, but not the MB group, which presented no difference in roughness before or after degradation. CT and AD groups showed greater roughness in CaC, ErC and EzC than in ArS. The SD group showed no difference in roughness when the specimens were polished with CaC, EzC or ArS, but those treated with ErC had greater roughness. In the MB group, the lower roughness values were found after using CaC and EzC, while the higher values were found using ErC or ArS. CLINICAL SIGNIFICANCE: As far as degradation resistance of nanofilled composite to hydrolysis, bacterial and dietary acids and enzymatic reactions is concerned, restorations that had been finished and polished with Al2O3-impregnated discs had the smoothest surfaces.

The effect of various surface treatments on the repair bond strength of denture bases produced by digital and conventional methods.

There is limited information on the repairability of prostheses produced with digital technology. This study aims to evaluate various surface treatments on flexural bond strength of repaired dentured base resins produced by digital and conventional methods. A total of 360 samples were prepared from one heat-polymerized, one CAD/CAM milled and one 3D printed denture base materials. All of the test samples were subjected to thermocycling (5-55 °C, 5000 cycles) before and after repair with auto-polymerizing acrylic resin. The test samples were divided into five subgroups according to the surface treatment: grinding with silicon carbide (SC), sandblasting with Al2O3 (SB), Er:YAG laser (L), plasma (P) and negative control (NC) group (no treatment). In addition, the positive control (PC) group consisted of intact samples for the flexural strength test. Surface roughness measurements were performed with a profilometer. After repairing the test samples, a universal test device determined the flexural strength values. Both the surface topography and the fractured surfaces of samples were examined by SEM analysis. The elemental composition of the tested samples was analyzed by EDS. Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis of data. SB and L surface treatments statistically significantly increased the surface roughness values of all three materials compared to NC subgroups (p < 0.001). The flexural strength values of the PC groups in all three test materials were significantly higher than those of the other groups (p < 0.001). The repair flexural strength values were statistically different between the SC-SB, L-SB, and NC-SB subgroups for the CAD/CAM groups, and the L-SC and L-NC subgroups for the 3D groups (p < 0.001). The surface treatments applied to the CAD/CAM and heat-polymerized groups did not result in a statistically significant difference in the repair flexural strength values compared to the NC groups (p > 0.05). Laser surface treatment has been the most powerful repair method for 3D printing technique. Surface treatments led to similar repair flexural strengths to untreated groups for CAD/CAM milled and heat-polymerized test samples.

The effects of impurities in carbide slag on the morphological evolution of CaCO3 during carbonation.

Carbide slag (CS) is a kind of solid waste generated by the hydrolysis of calcium carbide for acetylene production. Its major component is Ca(OH)2, which shows great potential in CO2 mineralization to produce CaCO3. However, the types of impurities in CS and their mechanisms for inducing the morphological evolution of CaCO3 are still unclear. In this work, the influence of impurities in CS on the morphology evolution of CaCO3 was investigated. The following impurities were identified in the CS: Al2O3, MgO, Fe2O3, SiO2 and CaCO3. Ca(OH)2 was used to study the influence of impurities (Al2O3 and Fe2O3) on the evolution of CaCO3 morphology during CS carbonation. Calcite (CaCO3) was the carbonation product produced during CS carbonation under varying conditions. The morphology of calcite was changed from cubic to rod-shaped, with increasing solid-liquid ratios. Moreover, rod-shaped calcite was converted into irregular particles with increasing CO2 flow rate and stirring speed. Rod-shaped calcite (CaCO3) was formed by CS carbonation at a solid-liquid ratio of 10:100 under a stirring speed of 600 rpm and a CO2 flow rate of 200 ml/min; and spherical calcite was generated during Ca(OH)2 carbonation under the same conditions. Al2O3 impurities had negligible effects on spherical CaCO3 during Ca(OH)2 carbonation. In contrast, rod-shaped CaCO3 was generated by adding 0.13 wt% Fe2O3 particles, similar to the content of Fe2O3 in CS. Rod-shaped calcite was converted into particulate calcite with increasing Fe2O3 content. The surface wettability and surface negative charge of Fe2O3 appeared to be responsible for the formation of rod-shaped CaCO3. This study enhances our understanding and utilization of CS and CO2 reduction and the fabrication of high-value rod-shaped CaCO3.

Purification and preparation of pure SiC with silicon cutting waste.

Recycling silicon cutting waste (SCW) plays a pivotal role in reducing environmental impact and enhancing resource efficiency within the semiconductor industry. Herein SCW was utilized to prepare SiC and ultrasound-assisted leaching was investigated to purify the obtained SiC and the leaching factors were optimized. The mixed acids of HF/H2SO4 works efficiently on the removal of Fe and SiO2 due to that HF can react with SiO2 and Si and then expose the Fe to H+. The assistance of ultrasound can greatly improve the leaching of Fe, accelerate the leaching rate, and lower the leaching temperature. The optimal leaching conditions are HF-H2SO4 ratio of 1:3, acid concentration of 3 mol/L, temperature of 50 °C, ultrasonic frequency of 45 kHz and power of 210 W, and stirring speed of 300 rpm. The optimal leaching ratio of Fe is 99.38%. Kinetic analysis shows that the leaching process fits the chemical reaction-controlled model.

Tubular graphitic carbon nitride-anchored on porous diatomite for enhanced solar energy efficiency in photocatalytic remediation and energy storage performance.

Dual functional materials can be beneficial for simultaneous application in different fields. Herein, tubular graphitic carbon nitride (TCN) was anchored on natural diatomite (DT) by performing a simple hydrothermal-calcination method and the as-obtained composite (TCN/DT) was utilized in both photocatalytic remediation and thermal energy storage. The optimal sample, TCN/DT/3, could degrade 88.9 % of tetracycline, which was about 2.87 times than that of the pristine TCN. This could be due to extended light absorption ability, altered band structure and enhanced separation rate of photoinduced carrier. The photocatalytic efficiency remained 78.0% after fifth cycle, indicating its reusability feature. The reaction was mainly driven by superoxide radicals as well as holes and hydroxyl radicals mediated the reaction. The TCN/DT/3/Vis system showed good performance at near-neutral pH, also the system could be efficiently performed under tap water and drinking water. On the other hand, the usage of TCN/DT/3 catalyst as a framework for shape-stabilized stearic acid (SA) based composite phase change materials (PCMs) was explored. The composite PCM exhibited higher thermal energy storage capacity accompanied with improved thermal conductivity in comparison with DT/PCM composite. This study presented a novel composite materials which exhibited a synergistic effect between TCN and DT, resulting in high photocatalytic activity and effective thermal energy storage capacity.

Electrochemically produced nano-TiO2-coated SiC membranes for photocatalytic water treatment: Preparation, characterization, and hydroxyl radical formation.

Photocatalytically active ceramic flat sheet membranes based on a nanostructured titanium dioxide (TiO2) coating were produced for photocatalytic water treatment. The nano-TiO2 layer was produced by a novel combination of magnetron sputtering of a thin titanium layer on silicon carbide (SiC) membranes, followed by electrochemical oxidation (anodization) and subsequent heat treatment (HT). Characterization by Raman spectra and field emission scanning electron microscopy proved the presence of a nanostructured anatase layer on the membranes. The influence of the titanium layer thickness on the TiO2 formation process and the photocatalytic properties were investigated using anodization curves, by using cyclovoltammetry measurements, and by quantifying the generated hydroxyl radicals (OH•) under UV-A irradiation in water. Promising photocatalytic activity and permeability of the nano-TiO2-coated membranes could be demonstrated. A titanium layer of at least 2 µm was necessary for significant photocatalytic effects. The membrane sample with a 10 µm Ti/TiO2 layer had the highest photocatalytic activity showing a formation rate of 1.26 × 10-6 mmol OH• s-1. Furthermore, the membranes were tested several times, and a decrease in radical formation was observed. Assuming that these can be attributed to adsorption processes of the reactants, initial experiments were carried out to reactivate the photocatalyzer.

Boosted photocatalytic performance of cobalt ferrite anchored g-C3N4 nanocomposite toward various emerging environmental hazardous pollutants degradation: insights into stability and Z-scheme mechanism.

In this study, a highly efficient CoFe2O4-anchored g-C3N4 nanocomposite with Z-scheme photocatalyst was developed by facile calcination and hydrothermal technique. To evaluate the crystalline structure, sample surface morphology, elemental compositions, and charge conductivity of the as-synthesized catalysts by various characterization techniques. The high interfacial contact of CoFe2O4 nanoparticles (NPs) with g-C3N4 nanosheets reduced the optical bandgap from 2.67 to 2.5 eV, which improved the charge carrier separation and transfer. The photo-degradation of methylene blue (MB) and rhodamine B (Rh B) aqueous pollutant suspension under visible-light influence was used to investigate the photocatalytic degradation activity of the efficient CoFe2O4/g-C3N4 composite catalyst. The heterostructured spinel CoFe2O4 anchored g-C3N4 photocatalysts (PCs) with Z-scheme show better photocatalytic degradation performance for both organic dyes. Meanwhile, the efficiency of aqueous MB and Rh B degradation in 120 and 100 min under visible-light could be up to 91.1% and 73.7%, which is greater than pristine g-C3N4 and CoFe2O4 catalysts. The recycling stability test showed no significant changes in the photo-degradation activity after four repeated cycles. Thus, this work provides an efficient tactic for the construction of highly efficient magnetic PCs for the removal of hazardous pollutants in the aquatic environment.

Fabrication and nanophotonic waveguide integration of silicon carbide colour centres with preserved spin-optical coherence.

Optically addressable spin defects in silicon carbide (SiC) are an emerging platform for quantum information processing compatible with nanofabrication processes and device control used by the semiconductor industry. System scalability towards large-scale quantum networks demands integration into nanophotonic structures with efficient spin-photon interfaces. However, degradation of the spin-optical coherence after integration in nanophotonic structures has hindered the potential of most colour centre platforms. Here, we demonstrate the implantation of silicon vacancy centres (VSi) in SiC without deterioration of their intrinsic spin-optical properties. In particular, we show nearly lifetime-limited photon emission and high spin-coherence times for single defects implanted in bulk as well as in nanophotonic waveguides created by reactive ion etching. Furthermore, we take advantage of the high spin-optical coherences of VSi centres in waveguides to demonstrate controlled operations on nearby nuclear spin qubits, which is a crucial step towards fault-tolerant quantum information distribution based on cavity quantum electrodynamics.

Porous Silicon Carbide (SiC): A Chance for Improving Catalysts or Just Another Active-Phase Carrier?

There is an obvious gap between efforts dedicated to the control of chemicophysical and morphological properties of catalyst active phases and the attention paid to the search of new materials to be employed as functional carriers in the upgrading of heterogeneous catalysts. Economic constraints and common habits in preparing heterogeneous catalysts have narrowed the selection of active-phase carriers to a handful of materials: oxide-based ceramics (e.g. Al2O3, SiO2, TiO2, and aluminosilicates-zeolites) and carbon. However, these carriers occasionally face chemicophysical constraints that limit their application in catalysis. For instance, oxides are easily corroded by acids or bases, and carbon is not resistant to oxidation. Therefore, these carriers cannot be recycled. Moreover, the poor thermal conductivity of metal oxide carriers often translates into permanent alterations of the catalyst active sites (i.e. metal active-phase sintering) that compromise the catalyst performance and its lifetime on run. Therefore, the development of new carriers for the design and synthesis of advanced functional catalytic materials and processes is an urgent priority for the heterogeneous catalysis of the future. Silicon carbide (SiC) is a non-oxide semiconductor with unique chemicophysical properties that make it highly attractive in several branches of catalysis. Accordingly, the past decade has witnessed a large increase of reports dedicated to the design of SiC-based catalysts, also in light of a steadily growing portfolio of porous SiC materials covering a wide range of well-controlled pore structure and surface properties. This review article provides a comprehensive overview on the synthesis and use of macro/mesoporous SiC materials in catalysis, stressing their unique features for the design of efficient, cost-effective, and easy to scale-up heterogeneous catalysts, outlining their success where other and more classical oxide-based supports failed. All applications of SiC in catalysis will be reviewed from the perspective of a given chemical reaction, highlighting all improvements rising from the use of SiC in terms of activity, selectivity, and process sustainability. We feel that the experienced viewpoint of SiC-based catalyst producers and end users (these authors) and their critical presentation of a comprehensive overview on the applications of SiC in catalysis will help the readership to create its own opinion on the central role of SiC for the future of heterogeneous catalysis.

The Analysis of Micro-Scale Deformation and Fracture of Carbonized Elastomer-Based Composites by In Situ SEM.

Carbonized elastomer-based composites (CECs) possess a number of attractive features in terms of thermomechanical and electromechanical performance, durability in aggressive media and facile net-shape formability, but their relatively low ductility and strength limit their suitability for structural engineering applications. Prospective applications such as structural elements of micro-electro-mechanical systems MEMS can be envisaged since smaller principal dimensions reduce the susceptibility of components to residual stress accumulation during carbonization and to brittle fracture in general. We report the results of in situ in-SEM study of microdeformation and fracture behavior of CECs based on nitrile butadiene rubber (NBR) elastomeric matrices filled with carbon and silicon carbide. Nanostructured carbon composite materials were manufactured via compounding of elastomeric substance with carbon and SiC fillers using mixing rolling mill, vulcanization, and low-temperature carbonization. Double-edge notched tensile (DENT) specimens of vulcanized and carbonized elastomeric composites were subjected to in situ tensile testing in the chamber of the scanning electron microscope (SEM) Tescan Vega 3 using a Deben microtest 1 kN tensile stage. The series of acquired SEM images were analyzed by means of digital image correlation (DIC) using Ncorr open-source software to map the spatial distribution of strain. These maps were correlated with finite element modeling (FEM) simulations to refine the values of elastic moduli. Moreover, the elastic moduli were derived from unloading curve nanoindentation hardness measurements carried out using a NanoScan-4D tester and interpreted using the Oliver-Pharr method. Carbonization causes a significant increase of elastic moduli from 0.86 ± 0.07 GPa to 14.12 ± 1.20 GPa for the composite with graphite and carbon black fillers. Nanoindentation measurements yield somewhat lower values, namely, 0.25 ± 0.02 GPa and 9.83 ± 1.10 GPa before and after carbonization, respectively. The analysis of fractography images suggests that crack initiation, growth and propagation may occur both at the notch stress concentrator or relatively far from the notch. Possible causes of such response are discussed, namely, (1) residual stresses introduced by processing; (2) shape and size of fillers; and (3) the emanation and accumulation of gases in composites during carbonization.

Portable electrochemical carbon cloth analysis device for differential pulse anodic stripping voltammetry determination of Pb2.

A novel electrochemical carbon cloth (CC) analysis device (eCAD) is proposed for the determination of Pb2+ in environmental water samples, which was assembled using a single-step functional CC as both the sensing and the substrate material. The modified CC was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectra, and electrochemical impedance spectroscopy. The increase in electrochemical activity is due to the increased defective extent and excellent electrochemical activity of CC. Under optimum conditions (viz. a pH value of 4.5, deposition time of 160 s), the sensor is capable of determining Pb2+ by differential pulse anodic stripping voltammetry (DPASV) at a typical working potential of - 1.0 V (vs. Ag/AgCl). Response is linear from 5.0 × 10-9 to 3.0 × 10-6 M Pb2+, and the detection limit is 4.8 nM (at S/N = 3). The sensor was successfully applied to the determination of Pb2+ in real samples, with apparent recoveries from 96.0 to 102.0% and a relative standard deviation of less than 3.4%. In addition, the integration of the sensor with signal collection components has enabled us to realize on-site analysis of Pb2+, which is highlighted as a new generation of electrode platform for the development of a portable analysis device.Graphical abstract.

ß-Hydroxybutyrate dehydrogenase decorated MXene nanosheets for the amperometric determination of ß-hydroxybutyrate.

MXene nanosheets of type Ti3C2Tx were modified with ß-hydroxybutyrate dehydrogenase and then used as a biosensor for amperometric sensing of ß-hydroxybutyrate. The MXene and the nanocomposite were characterized by X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The MXene has a layered structure and proved to be an excellent immobilization matrix providing good compatibility with the enzyme ß-hydroxybutyrate dehydrogenase. The MXene-based biosensor, best operated at a potential of - 0.35 V (vs. Ag/AgCl), displays a wide linear range (0.36 to 17.9 mM), a sensitivity of 0.480 µA mM-1 cm-2, and a low detection limit (45 µM). The biosensor was successfully applied to the determination of ß-hydroxybutyrate in (spiked) real serum samples. Graphical abstract Schematic representation of the synthesis and decoration of Mxene 2D sheets with ß-hydroxybutyrate dehydrogenase for the amperometric determination of ß-hydroxybutyric acid.

SiC-functionalized fluorescent aptasensor for determination of Proteus mirabilis.

Aptamer-modified SiC quantum dots (DNA-SiC QDs) as fluorescent aptasensor are described for the determination of Proteus mirabilis. The SiC QDs were synthesized through one-pot hydrothermal method with particle sizes of about 14 nm. The amino-modified aptamers against P. mirabilis were conjugated to the surfaces of SiC QDs for bacteria recognition. The aptamer with an affinity for target protein can bound to P. mirabilis and this causes a decrease in the fluorescence intensity of DNA-SiC QDs. P. mirabilis levels were tested by the aptasensor within 35 min with fluorescence excitation/emission maxima at 320/420 nm. The linear range is from 103 to 108 CFU mL-1 and the limit of detection is 526 CFU mL-1 (S/N = 3). The aptasensor was used for determination of P. mirabilis in pure milk samples and obtained good accuracy (87.6-104.5%) and recovery rates (85-110.2%) were obtained. The detection in simulated forensic identification samples (pure milk, milk powder, blood, and urine) obtained gave satisfactory coincidence rates with the method of bacterial isolation and identification as standard. These results demonstrate that the fluorescent aptasensor is a potential tool for identification of P. mirabilis in forensic food poisoning cases. Graphical abstract Determination of P. mirabilis is based on SiC QDs fluorescence aptasensor. The SiC QDs with plentiful carboxyl groups on the surface can be synthesized via one-pot hydrothermal route. After activated by EDC/NHS, the SiC QDs can bind to aptamer to form fluorescence aptasensors. When the target P. mirabilis exists, the fluorescence of aptasensor will be quenched and the determination of the P. mirabilis based on the fluorescence change can be analyzed.

Fundamental research on semiconductor SiC and its applications to power electronics.

Today, the silicon carbide (SiC) semiconductor is becoming the front runner in advanced power electronic devices. This material has been considered to be useful for abrasive powder, refractory bricks as well as ceramic varistors. Big changes have occurred owing to the author's inspirational idea in 1968 to "make transistors from unusual material". The current paper starts by describing the history of SiC research involving fundamental studies by the author's group: unique epitaxial crystal growth techniques, the physical characterization of grown layers and processes for device fabrication. Trials for fabricating SiC power devices and their characteristics conducted until 2004 are precisely described. Recent progress in SiC crystal growth and peripheral techniques for SiC power devices are introduced. Finally, the present progress concerning SiC power devices is introduced together with the implementation of those devices in society.

Unprecedented Piezoresistance Coefficient in Strained Silicon Carbide.

Reports reveal that the piezoresistance coefficients of silicon carbide (SiC) nanowires (NWs) are 2 to 4 times smaller than those of their corresponding bulk counterparts. It is a challenge to eliminate contamination in adhering NWs onto substrates. In this study, a new setup was developed, in which NWs were manipulated and fixed by a goat hair and conductive silver epoxy in air, respectively, in the absence of any depositions. The goat hair was not consumed during manipulation of the NWs. The process took advantage of the stiffness and tapered tip of the goat hair, which is unlike the loss issue of beam sources in depositions. With the new fixing method, in situ transmission electron microscopy (TEM) electromechanical coupling measurements were performed on pristine SiC NWs. The piezoresistance coefficient and carrier mobility of SiC NW are -94.78 × 10-11 Pa-1 and 30.05 cm2 V-1 s-1, respectively, which are 82 and 527 times respectively greater than those of SiC NWs reported previously. We, for the first time, report that the piezoresistance coefficient of SiC NW is 17 times those of its bulk counterparts. These findings provide new insights to develop high performance SiC devices and to help avoid catastrophic failure when working in harsh environments.

Fillers as Heaters for Photothermal Polymerization upon NIR Light.

Photo-induced thermal polymerization upon near-infrared (NIR) light irradiation has been reported in the literature. In this approach, a component able to convert the NIR light into heat must be used in combination with a thermal initiator to initiate the free-radical polymerization of (meth)acrylates. In recent studies, some absorbers have been presented as very efficient heat generators (called heaters). In the present work, different fillers are investigated as heaters and compared to organic NIR absorbers. An alkoxyamine (e.g., BlocBuilder-MA) is used as thermal initiator and is dissociated by the heat generated by the NIR photoexcitation of the fillers. In the present work, several fillers are examined: graphene oxide, graphene nanoplatelets, multi-walled carbon nanotubes, and silicon carbide. Due to the energy of the photon delivered, NIR light curing is challenging but offers several advantages compared to visible light. The most interesting feature is the deeper penetration of the light inside the photocurable resin, enabling the polymerization of thick samples. Parallel to this, incorporation of fillers in resins allows unique access to composites through photothermal polymerization of (meth)acrylates. Three different wavelengths of irradiation have been studied: 785, 940, and 1064 nm.

Ultrafine Fe3C nanoparticles embedded in N-doped graphitic carbon sheets for simultaneous determination of ascorbic acid, dopamine, uric acid and xanthine.

A pyrolytic method is described for preparation of ultrafine Fe3C nanoparticles incorporated into N-doped graphitic carbon nanosheets (Fe3C@NGCSs). Iron phthalocyanine and graphitic carbon nitride (g-C3N4) are used as starting materials. The hybrid nanocomposite was placed on a glassy carbon electrode (GCE) and then applied to simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and xanthine (XA). Figures of merits are as follows: for AA, the linear response range covers the 54.0-5491.0 µM range, the lower detection limit is 16.7 µM, and the best working voltage (vs. the saturated calomel electrode (SCE)) is 0.05 V. The respective data for DA are 1.2-120.8 µM, 0.34 µM and 0.19 V (vs. SCE). For UA, the respective data are 4.8-263.0 µM, 1.4 µM and 0.32 V (vs. SCE), and for XA the data are 4.8-361.0 µM, 1.5 µM and 0.71 V (vs. SCE). The method was successfully applied to their simultaneous determination in spiked serum samples. Graphical abstract Ultrafine Fe3C nanoparticles embedded in N-doped graphitic carbon sheets for simultaneous determination of ascorbic acid, dopamine, uric acid and xanthine.

Bacteria-targeting BSA-stabilized SiC nanoparticles as a fluorescent nanoprobe for forensic identification of saliva.

Forensic saliva identification represents an increasingly useful auxiliary means of crime investigations, particularly in sex crimes. Salivary bacteria detection techniques have been shown to be viable methods for identifying the presence of saliva. A one-pot method is described for the fabrication of bovine serum albumin-stabilized SiC nanoparticles (SiC@BSA NPs). The SiC@BSA NPs were conjugated to antibacterial peptide GH12 to allow for fluorometric detection and imaging of bacteria in saliva. More specifically, the nanoprobe, with fluorescence excitation/emission maxima at 320/410 nm, was used to detect the oral bacteria S. salivarius levels. The detection limit is 25 cfu·mL-1, and the assay can be performed within 40 min. The nanoprobe was also used to detect bacteria in forensic body fluids including blood, urine, and semen. In all cases, positive results were obtained with (mixed) samples containing saliva, while other saliva samples without saliva showed negative results. Fluorescent images of S. salivarius cells were obtained by implementing a high-content image analysis system. These results suggest that this new nanoprobe can be applied to screen for forensic saliva stains. Graphical abstractSchematic representation of the preparation of SiC@BSA-GH12 nanoprobe for fluorometric detection and imaging of S. salivarius in saliva.