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strict flexibility requirements in neural implanted stimulations, the use of conventional thick and bulky packages is no longer applicable, posing major technical issues such as short device lifetime and long-term stability.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.

Toward High-Performance Piezoresistive Polymer Derived SiOC Ceramics through Masked Stereolithography 3D Printing with ß-Silicon Carbide Nanopowder Reinforcement.

Enhancing the piezoresistivity of polymer-derived silicon oxycarbide ceramics (SiOCPDC ) is of great interest in the advancement of highly sensitive pressure/load sensor technology for use in harsh and extreme working conditions. However, a facile, low cost, and scalable approach to fabricate highly piezoresistive SiOCPDC below 1400 °C still remains a great challenge. Here, the fabrication and enhancement of piezoresistive properties of SiOCPDC reinforced with ß-SiC nanopowders (SiCNP ) through masked stereolithography-based 3D-printing and subsequent pyrolysis at 1100 °C are demonstrated. The presence of free carbon in SiCNP augments high piezoresistivity in the fabricated SiCNP -SiOCPDC composites even at lower pyrolysis temperatures. A gauge factor (GF) in the range of 4385-5630 and 6129-8987 with 0.25 and 0.50 wt% of SiCNP , respectively is demonstrated, for an applied pressure range of 0.5-5 MPa at ambient working conditions. The reported GF is significantly higher compared to those of any existing SiOCPDC materials. This rapid and facile fabrication route with significantly enhanced piezoresistive properties makes the 3D-printed SiCNP -SiOCPDC composite a promising high-performance material for the detection of pressure/load in demanding applications. Also, the overall robustness in mechanical properties and load-bearing capability ensures its long-term stability and makes it suitable for challenging and severe environment applications.

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.

Implementing an Air Suction Effect Induction Strategy to Create Super Thermally Insulating and Superelastic SiC Aerogels.

Silicon carbide (SiC) aerogels are promising thermal insulators that are lightweight and possess high thermal stability. However, their application is hindered by their brittleness. Herein, an air suction effect induction (ASEI) strategy is proposed to fabricate a super thermally insulating SiC aerogel (STISA). The ASEI strategy exploits the air suction effect to subtly regulate the directional flow of the SiO gas, which can induce directional growth and assembly of SiC nanowires to form a directional lamellar structure. The sintering time is significantly reduced by >90%. Significant improvements in the compression and elasticity performance of the STISA are achieved upon the formation of a directional lamellar structure through the ASEI strategy. Moreover, the lamellar structure endows the STISA with an ultralow thermal conductivity of 0.019 W m-1 K-1 . The ASEI strategy paves the way for structural design of advanced ceramic aerogels for super thermal insulation.

Engineered Silicon Carbide Three-Dimensional Frameworks through DNA-Prescribed Assembly.

The ability to create nanoengineered silicon carbide (SiC) architectures is important for the diversity of optical, electronic, and mechanical applications. Here, we report a fabrication of periodic three-dimensional (3D) SiC nanoscale architectures using a self-assembled and designed 3D DNA-based framework. The assembly is followed by the templating into silica and subsequent conversion into SiC using a lower temperature pathway (<700 °C) via magnesium reduction. The formed SiC framework lattice has a unit size of about 50 nm and domains over 5 µm, and it preserves the integrity of the original 3D DNA lattice. The spectroscopic and electron microscopy characterizations reveal SiC crystalline morphology of 3D nanoarchitectured lattices, whereas electrical probing shows 2 orders of magnitude enhancements of electrical conductivity over the precursor silica framework. The reported approach offers a versatile methodology toward creating highly structured and spatially prescribed SiC nanoarchitectures through the DNA-programmable assembly and the combination of templating processes.

Fabrication of zinc-loaded silicon carbide nanocomposite for in vitro cell viability and in vivo wound dressing care.

AIM: In this investigation, Zinc-silicon carbide (Zn-SiC) materials were fabricated by a simple approach by using Zn nanoparticles (Zn-NPs) loaded on silicon carbide (SiC) with enhanced antibacterial and healing activity. METHODS: Zn-NPs loaded on SiC fabricated by the DIY laser melting technique. The TEM and Zeta-sizer confirmed the morphology and size of the nanoparticles. The characterisation was done using Fourier transforms infra-red spectroscopy, and X-ray diffraction, thermogravimetric analysis. Further, the fabricated nanoparticles were evaluated for their mechanical properties and biocompatibility under storage conditions. In vivo wound healing was measured by observing a percentage reduction in the wound. RESULTS: Zn-SiC NPs have 54.6 ± 5.25 nm mean particle size, -15.9 ± 2.35 mV zeta potential with 0.187 ± 0.05 polydispersity index. The nanoparticles showed good biocompatibility and in vivo wound healing properties. CONCLUSIONS: These results strongly support the possibility of using these Zn particles loaded on SiC NPs as a promising wound healing agent after caesarean section.

Color perceptibility and validity of silicon carbide-based protective coatings for dental ceramics.

STATEMENT OF PROBLEM: A silicon carbide (SiC) protective coating has been developed for dental ceramics, but whether the coated ceramics can match the classical VITA shades is unclear. PURPOSE: The purpose of this observational in vitro study was to evaluate the color adaptability of SiC-coated dental ceramics by testing the hypotheses that SiC-coated disks can be fabricated to match standard tooth shades and have a perceptible color match rate of at least 50% for disks with a color difference (ΔE)<2.0. The effects of ΔE, shade hue, shade value, observer sex, years of experience, profession, and shade guide orientation on color perception were studied. MATERIAL AND METHODS: SiC-coated disks were fabricated to color match (ΔEab<3.3) all 16 VITA classical shades. Uncoated disks of each VITA shade were used as the reference materials to determine whether the SiC-coated disks were color matched to the classical VITA shade guide. Three ΔE formulas (76, 94, and 2000) were applied and compared. Participants (N=120) with an average of 22 years of experience included dental school students, dental faculty members, and dental assistants. Pseudoisochromatic plate and the Farnsworth D-15 Panel test for assessing color deficiency and color blindness were administered. Participants then attempted to match SiC-coated disks to standard shade guides arranged by value or hue. All spectrophotometer readings and color matching were conducted in a light booth with standardized daylight illumination. Statistical analysis used the Fisher's exact test to determine factors associated with improved matching performance (α=.05). RESULTS: A significant difference in color match rate was found between disks with ΔE<2.0 (63.9%) and ΔE≥2.0 (41.7%) (P<.001). Arranging shade by value (72.2%) instead of hue (67.2%) produced better color matching (P<.001). Sex (P=.430), profession (P=.708), and years of experience (P=.902) had no significant influence on color matching. CONCLUSIONS: SiC-coated disks were successfully fabricated to match all VITA classical shades, and clinical visual color matching results confirmed that ΔE was a useful metric in optimizing color matching for the SiC-coated dental ceramics.

Trident Nano-Indexing the Proteomics Table: Next-Version Clustering of Iron Carbide NPs and Protein Corona.

Protein corona composition and precise physiological understanding of differentially expressed proteins are key for identifying disease biomarkers. In this report, we presented a distinctive quantitative proteomics table of molecular cell signaling differentially expressed proteins of corona that formed on iron carbide nanoparticles (NPs). High-performance liquid chromatography/electrospray ionization coupled with ion trap mass analyzer (HPLC/ESI-Orbitrap) and MASCOT helped quantify 142 differentially expressed proteins. Among these proteins, 104 proteins showed upregulated behavior and 38 proteins were downregulated with respect to the control, whereas 48, 32 and 24 proteins were upregulated and 8, 9 and 21 were downregulated CW (control with unmodified NPs), CY (control with modified NPs) and WY (modified and unmodified NPs), respectively. These proteins were further categorized on behalf of their regularity, locality, molecular functionality and molecular masses using gene ontology (GO). A STRING analysis was used to target the specific range of proteins involved in metabolic pathways and molecular processing in different kinds of binding functionalities, such as RNA, DNA, ATP, ADP, GTP, GDP and calcium ion bindings. Thus, this study will help develop efficient protocols for the identification of latent biomarkers in early disease detection using protein fingerprints.

Microbially induced carbonate precipitation via methanogenesis pathway by a microbial consortium enriched from activated anaerobic sludge.

AIMS: Various applications of microbially induced carbonate precipitation (MICP) has been proposed. However, most studies use cultured pure strains to obtain MICP, ignoring advantages of microbial consortia. The aims of this study were to: (i) test the feasibility of a microbial consortium to produce MICP; (ii) identify functional micro-organisms and their relationship; (iii) explain the MICP mechanism; (iv) propose a way of applying the MICP technique to soil media. METHODS AND RESULTS: Anaerobic sludge was used as the source of the microbial consortium. A laboratory anaerobic sequencing batch reactor and beaker were used to perform precipitation experiment. The microbial consortium produced MICP with an efficiency of 96·6%. XRD and SEM analysis showed that the precipitation composed of different-size calcite crystals. According to high-throughput 16S rRNA gene sequencing, the functional micro-organisms included acetogenic bacteria, acetate-oxidizing bacteria and archaea Methanosaeta and Methanobacterium beijingense. The methanogenesis acetate degradation provides dissolved inorganic carbon and increases pH for MICP. A series of reactions catalysed by many enzymes and cofactors of methanogens and acetate-oxidizers are involved in the acetate degradation. CONCLUSION: This work demonstrates the feasibility of using the microbial consortium to achieve MICP from an experimental and theoretical perspective. SIGNIFICANCE AND IMPACT OF THE STUDY: A method of applying the microbial-consortium MICP to soil media is proposed. It has the advantages of low cost, low environmental impact, treatment uniformity and less limitations from natural soils. This method could be used to improve mechanical properties, plug pores and fix harmful elements of soil media, etc.

PII-like signaling protein SbtB links cAMP sensing with cyanobacterial inorganic carbon response.

Cyanobacteria are phototrophic prokaryotes that evolved oxygenic photosynthesis ∼2.7 billion y ago and are presently responsible for ∼10% of total global photosynthetic production. To cope with the evolutionary pressure of dropping ambient CO2 concentrations, they evolved a CO2-concentrating mechanism (CCM) to augment intracellular inorganic carbon (Ci) levels for efficient CO2 fixation. However, how cyanobacteria sense the fluctuation in Ci is poorly understood. Here we present biochemical, structural, and physiological insights into SbtB, a unique PII-like signaling protein, which provides new insights into Ci sensing. SbtB is highly conserved in cyanobacteria and is coexpressed with CCM genes. The SbtB protein from the cyanobacterium Synechocystis sp. PCC 6803 bound a variety of adenosine nucleotides, including the second messenger cAMP. Cocrystal structures unraveled the individual binding modes of trimeric SbtB with AMP and cAMP. The nucleotide-binding pocket is located between the subunit clefts of SbtB, perfectly matching the structure of canonical PII proteins. This clearly indicates that proteins of the PII superfamily arose from a common ancestor, whose structurally conserved nucleotide-binding pocket has evolved to sense different adenyl nucleotides for various signaling functions. Moreover, we provide physiological and biochemical evidence for the involvement of SbtB in Ci acclimation. Collectively, our results suggest that SbtB acts as a Ci sensor protein via cAMP binding, highlighting an evolutionarily conserved role for cAMP in signaling the cellular carbon status.

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.