Sp3 Content Research Articles

Effect of Fuel Composition on Carbon Black Formation Pathways

Differences in lamellae length, stacking, and particularly a difference in the core-to-shell radial structure are observed for carbon blacks produced using different feedstocks. Carbon black (CB) produced using a coal tar (CT) feedstock formed particles with amorphous cores exhibiting a sharp transition to extended lamellae oriented about the periphery of the particle. In contrast, the carbon black produced from fluidized catalytic cracker (FCC) decant oil as feedstock formed particles with a single nucleated core possess a rather uniform radial transition—reflecting the presence of ordered, concentric lamellae across most of the particle radius. Minimal disorder was observed in the core while the undulations in perimeter lamellae were fewer. Our interpretation for these structural dissimilarities is premised on differences in fuel composition, specifically component classes as found by saturate, aromatic, resin, asphaltene (SARA) analysis. These in turn lead to variation in the relative rates of particle nucleation and particle growth by pyrolysis products, moderated by temperature. Electron energy loss spectroscopy reveals radial variation in the sp2 content between the different feedstocks consistent with observed nanostructures. Collectively these results are interpreted in terms of an offset in nucleation and growth—dependent upon the relative contributions of feedstock aromatic content and pyrolysis processes to particle nucleation and growth. To further test the postulate of different formation conditions for the two carbon blacks pulsed laser annealing was applied. The high temperature heating accentuated the dissimilarities in nanostructure and chemistry—leading to stark dissimilarities. These differences were also manifested by comparing oxidative reactivity.

Rare-earth modified amorphous carbon films: Effects of erbium and gadolinium on the structural evolution and mechanical properties

Modifying amorphous carbon (a-C) with rare-earth elements is a highly auspicious concept to synthetize functional films with unique characteristics. Among the rare earth elements, Er and Gd demonstrate abundant physicochemical properties and, hence, are of remarkable interest for the element modification of a-C films. Therefore, Er-containing a-C:Er and Gd-containing a-C:Gd films are prepared in a reactive-free magnetron sputtering process. The a-C:Er and a-C:Gd films have an amount of up to 5 at.-% Er and 4.8 at.-% Gd.High-resolution x-ray photoelectron spectroscopy analyses show the formation of ErC and GdC components, which rise proportionally with increasing amount of the rare-earth element. The addition of Er and Gd lowers the sp3 content of C bonds. At the highest concentrations of the respective rare-earth elements, the a-C:Er and a-C:Gd films exhibit a reduced sp3 content of 8%. The number and size of sp2‑carbon clusters in the amorphous network are enhanced with increasing amount of Er and Gd which is evaluated by Raman scattering measurements. X-ray diffraction analyses reveal Er and Gd carbide phases, indicating the formation of a nanocomposite structure consisting of carbidic nanocrystallites and an a-C network. In nanoindentation tests, the non-modified a-C demonstrates a hardness of (21.7 ± 1.6) GPa and an elastic modulus of (232 ± 10) GPa. With increasing Er and Gd contents, the hardness linearly decreases to (16.7 ± 0.9) GPa and (14.8 ± 0.9) GPa, respectively. An analogous behavior is also identified for the elastic modulus. The reduced hardness and elastic modulus are attributed to the lower sp3 content and the larger number and size of the sp2-hybridized carbon atoms. Additionally, the adhesion was slightly improved by the addition of Er and Gd in comparison to non-modified a-C.

A comprehensive characterization of culturable endophytic bacteria of Paris polyphylla and their potential role in microalgal growth in co-culture

Expanding endophytes of endangered medicinal plant Paris polyphylla can provide a means to study endo-symbiotic relationships with emphasis on different traits such as plant growth promotion (PGP), host-defence mechanism, and secondary metabolites production. As in many instances, endophytic isolates selected based on few traits fail when they are further screened for their direct role in plants. Therefore, in this study, we aimed to conduct comprehensive analyses on the under-explored endophytic bacterial community of P. polyphylla from the Himalayan mountains. Culture-dependent method was adapted to isolate under-explored endophytic bacterial community from the rhizomes of P. polyphylla. Isolates were identified using 16S rRNA gene sequencing and screened for different characteristics such as ability to grow in different temperatures, pH, and NaCl concentration, siderophore production, phosphate solubilisation, and plant cell wall-degrading enzymes production. Key genes such as sfp, ituD, and genes encoding for NRPS, and PKS clusters involved in particular traits were identified. A total of 186 endophytic isolates were characterized, and assigned to 4 major phyla Firmicutes, Gammaproteobacteria, Alphaproteobacteria, and Actinobacteria. The stringent methodology identified 7.52% and 2.15% of the isolates as siderophore producers and phosphate solubilisers respectively. Draft genome of the potential PGP endophyte Bacillus paralicheniformis PPE102 was obtained and investigated for various traits related to plant-microbe interactions. Co-culture experiments showed that PPE102 induced growth and had a positive impact on the biochemical content of photosynthetic microalga Micractinium sp. GA001. This debut attempt characterized exclusive collection of endophytic bacteria from P. polyphylla. This isolated community can be further explored for unique, and commercially-important biological compounds.

The effects of Cr and B doping on the mechanical properties and tribological behavior of multi-layered hydrogenated diamond-like carbon films

To enhance the adhesion strength and tribological properties of hydrogenated diamond-like carbon (H-DLC) films, the multi-layered H-DLC films consisting of a function layer with chromium and boron doping, Cr-C and Cr-H-DLC transition layer and a Cr bonding layer were prepared on 52100 steel through the unbalanced magnetron sputtering system. The influence of Cr and B doping on the mechanical properties and tribological performance were investigated. The results indicated that the structure of H-DLC, Cr-H-DLC and B-H-DLC films was compact. There were no peelingflake, delamination, and crack between the films and substrate. Raman spectra showed that the value of ID/IG increased with the Cr and B doping, which indicated that the sp3 content inside the H-DLC film decreased. Compared with the atmospheric condition, the coefficient of friction and wear rate of those films were higher than that in vacuum. According to the Raman spectra of the wear track, it was found that the graphitization of sliding interface theory had its limitations. The mechanical wear of those films was dominated by the abrasive and oxidative wear in the atmospheric environment. Owing to the passivation of the hydrogen atoms, the abrasive wear and adhesive wear was the main failure mechanism in vacuum.

Design of thin DLC/TiO2 film interference coatings on glass screen protector using a neon–argon-based gas injection magnetron sputtering technique

This paper reports the results obtained from the deposition of diamond-like carbon (DLC) films on glass substrates by gas injection magnetron sputtering method. The conducted studies aimed to evaluate if the plasma discharge that is generated by varying the proportions of neon−argon (Ne−Ar) gases during pulsed injections (0%–100%) would promote the synthesis of DLC films with desirable sp3 phase by means of electron impact-induced plasma interactions. The obtained DLC films showed the presence of sp3 (CC) hybridized bonds along the Gaussian distribution curve, which revealed that a maximum sp3 content in the range of 32%–45% was obtained along the 40% injection of Ne gas, based on the analysis of the C1s core-level spectra and Raman spectroscopy. A 25% gain in hardness (H) and resistance to cracking (H3/E2) were also observed in the sp3-rich DLC sample (24.1 ± 4 GPa and 0.29 ± 0.04), thus promoting its use in various nanomechanical systems. The change in the sp3/sp2 fraction ratio, demonstrated in this research, corresponded well to a calculated model of graded optical bandgap in the range from 0.53 to 3.01 eV. However, to further minimize the parasitic reflectance from a significant share of sp2 (C=C) domains, thin titanium dioxide (TiO2) (8–36 nm) layers were deposited on the DLC surface, which provided maximum antireflective effect due to interference shift. A significant increase in visible–near-infrared transmittance (up to 87%) was observed as a result of such an interference in DLC/TIO2 bilayers. Our results have practical applications and aid in the design of functional nanocoating structures which are tremendously favored and required to improve the toughness of commercially available glass protectors in hostile environmental conditions.

Deconvolution process approach in Raman spectra of DLC coating to determine the sp3 hybridization content using the ID/IG ratio in relation to the quantification determined by X-ray photoelectron spectroscopy

Raman spectroscopy has contributed to many fields of materials science, for example, in studies addressing Diamond-Like Carbon coatings. In the literature, discussions have arisen due to the various interpretations of Raman spectra and some studies have not recommended using it to measure sp2 and sp3 hybridization contents. This article addresses the deconvolution process in Raman spectra, manipulating the Raman shift interval, the presence of Savitzky-Golay smoothing and the appearance of additional bands. X-ray photoelectron spectroscopy was used to quantify the sp2 and sp3 contents, which are discussed below in relation to the ID/IG ratio and the prediction of the amorphization trajectory of graphite. In an attempt to find a relationship between these characterization techniques, a polynomial equation was developed from thirty-three experimental results researched in the literature. The results indicated a coating belonging to the a-C:H class containing 18% of sp3. The relationship between the spectroscopies was complementary and the graphite amorphization trajectory was assertive. The coefficient of determination and the standard deviation proved to be useful parameters for selecting the representative spectrum of the coating. Neglecting or not the appearance of an additional band can provide modifications to the ID/IG ratio at the level of 52%. Representative results of the ID/IG ratio indicated the hypothesis of considering the intensity of the bands only as a function of height. The sp3 content predicted by the equation was maximized to any selected ID/IG value when the G Band was centered at approximately 1559 cm−1. It was observed that the equation can be used qualitatively with less errors in conditions where the deconvolutions present parameters similar to the experimental results whose sp3 content is between 20% and 39.9%.

Glassy carbon manufacture using rapid photonic curing

Photonic curing was explored as a rapid method for producing glassy carbon coatings, reducing processing time from ~ 20 h for conventional thermal processing down to ~ 1 min. A resole-type thermoset polymer resin coated on steel foil was used as a precursor, placed in a nitrogen purged container and exposed to high energy light (~ 27 J/cm2 per pulse for up to 20 pulses). Comparison samples were produced at 800 °C using a conventional nitrogen purged thermal route. For both photonic and conventionally produced coatings, Raman spectroscopy and primary peak XPS data showed sp2 bonded carbon, indicative of bulk glassy carbon. This transformation evolved with increasing number of pulses, and therefore amount of energy transferred to the coating. The produced coatings were resilient, highly smooth, with no evidence of surface defects. XPS analysis indicated greater sp3 content at the immediate surface (5–10 nm) for photonic cured carbon compared with thermally cured carbon, likely due to the local environment (temperature, atmosphere) around the surface during conversion. The ability to rapidly manufacture glassy carbon coatings provides new opportunities to expand the window of applications of glassy carbons in coatings towards large-scale high volume applications.

Reduction of metal nanoparticle decorated flexible graphene oxide by laser at various temperatures and under selected atmospheres

In situ Raman spectroscopy of flexible films of bare graphene oxide (GO) and GO decorated with Pt and Au nanoparticles (NPs) were examined upon exposure to synthetic air and 1% hydrogen in synthetic air. Initially, GO possesses an sp2 rich-structure at room temperature; however, it suffers from a drastic sp2 loss at higher temperatures under argon laser exposure leading to structural damage above 65 °C. Conversely, metal nano particle (MNP) decorated GO undergoes a drastic reduction of sp2 content mainly due to an increased defect density. In MNP composites, the formation rate of reduced graphene oxide (rGO) elevates at higher temperatures leading to an improvement in the sp2 fraction to some extent under argon laser exposure. In fact, the optical properties of MNP decorated GO drastically change against those of bare GO. Despite Pt NPs demonstrating a large catalytic effect with temperature, Au NPs do not. Similarly, the catalytic effect of Pt-GO gives rise to a slight excess in rGO formation in favor of the sp2 domain recovery. Here, there is a dominant temperature effect and a minor catalytic effect during laser exposure to GO.

Revisiting Discharge Mechanism of CFx as a High Energy Density Cathode Material for Lithium Primary Battery

AbstractLithium/fluorinated graphite (Li/CFx) primary batteries show great promise for applications in a wide range of energy storage systems due to their high energy density (>2100 Wh kg–1) and low self‐discharge rate (<0.5% per year at 25 °C). While the electrochemical performance of the CFx cathode is indeed promising, the discharge reaction mechanism is not thoroughly understood to date. In this article, a multiscale investigation of the CFx discharge mechanism is performed using a novel cathode structure to minimize the carbon and fluorine additives for precise cathode characterizations. Titration gas chromatography, X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, cross‐sectional focused ion beam, high‐resolution transmission electron microscopy, and scanning transmission electron microscopy with electron energy loss spectroscopy are utilized to investigate this system. Results show no metallic lithium deposition or intercalation during the discharge reaction. Crystalline lithium fluoride particles uniformly distributed with <10 nm sizes into the CFx layers, and carbon with lower sp2 content similar to the hard‐carbon structure are the products during discharge. This work deepens the understanding of CFx as a high energy density cathode material and highlights the need for future investigations on primary battery materials to advance performance.

Systematic Review: Phytochemical Content and Pharmacological Effects of Chrysanthemum sp.

Chrysanthemum sp. is a plant often used by the community as an ornamental plant, drink, and traditional medicine. This study aims to examine the plant Chrysanthemum sp. from the aspect of phytochemical and pharmacological activity. The review method used in this study is the PRISMA method. Sources of data obtained using databases electronic from PubMed and Google Scholar. This review shows that plants Chrysanthemum sp. have phytochemical and pharmacological potential. The compounds contained in theplant Chrysanthemum sp. are morphine, genistein, hydantoin, limonene, g-terpinene, a-pinene, a-terpenyl acetate, 4-terpenyl acetate, a-calacorene, a-cedrene, b-bourbobene, elemol, 2- hexenal, and orphenadrine. Chrysanthemum sp. plants have anticancer, antibacterial, antioxidant, antifungal, analgesic, anti-inflammatory, and anticonsulvan activities.

Bias-Enhanced Formation of Metastable and Multiphase Boron Nitride Coating in Microwave Plasma Chemical Vapor Deposition.

Boron nitride (BN) is primarily a synthetically produced advanced ceramic material. It is isoelectronic to carbon and, like carbon, can exist as several polymorphic modifications. Microwave plasma chemical vapor deposition (MPCVD) of metastable wurtzite boron nitride is reported for the first time and found to be facilitated by the application of direct current (DC) bias to the substrate. The applied negative DC bias was found to yield a higher content of sp3 bonded BN in both cubic and metastable wurtzite structural forms. This is confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Nano-indentation measurements reveal an average coating hardness of 25 GPa with some measurements as high as 31 GPa, consistent with a substantial fraction of sp3 bonding mixed with the hexagonal sp2 bonded BN phase.

Ultrahard bulk amorphous carbon from collapsed fullerene.

Amorphous materials inherit short- and medium-range order from the corresponding crystal and thus preserve some of its properties while still exhibiting novel properties1,2. Due to its important applications in technology, amorphous carbon with sp2 or mixed sp2-sp3 hybridization has been explored and prepared3,4, but synthesis of bulk amorphous carbon with sp3 concentration close to 100% remains a challenge. Such materials inherit the short-/medium-range order of diamond and should also inherit its superior properties5. Here, we successfully synthesized millimetre-sized samples-with volumes 103-104 times as large as produced in earlier studies-of transparent, nearly pure sp3 amorphous carbon by heating fullerenes at pressures close to the cage collapse boundary. The material synthesized consists of many randomly oriented clusters with diamond-like short-/medium-range order and possesses the highest hardness (101.9 ± 2.3 GPa), elastic modulus (1,182 ± 40 GPa) and thermal conductivity (26.0 ± 1.3 W m-1 K-1) observed in any known amorphous material. It also exhibits optical bandgaps tunable from 1.85 eV to 2.79 eV. These discoveries contribute to our knowledge about advanced amorphous materials and the synthesis of bulk amorphous materials by high-pressure and high-temperature techniques and may enable new applications for amorphous solids.

Influence of gradient interlayer thickness on corrosion and tribological behavior of Ti-containing multilayer graphite-like carbon films

Structural design is a crucial strategy to improve the service performance of amorphous carbon films in aggressive environments. In this study multilayered graphite-like carbon (GLC) films with adhesive layer/gradient interlayer/doping layer architectures with varied gradient interlayer thickness were deposited on 316L stainless steel substrates by closed field unbalanced magnetron sputtering. The effect of gradient interlayer thickness on microstructure, mechanical, tribological and corrosion behavior of the GLC films was investigated. The results show that the mechanical properties and bonding strength decrease with increasing gradient interlayer thickness due to the increased sp2 content, surface roughness and decreased film integrity. The friction coefficient curves in ambient air and 3.5% NaCl solution show similar three-stage feature with distinctive wear mechanism in stage III. The decreased mechanical properties and loose microstructure of GLC films with thicker gradient interlayer thickness caused the decreased wear resistance in both ambient air and NaCl solution. In comparison with the uncoated substrate, the GLC films show improved corrosion resistance in NaCl solution, which also decreases with the increased gradient interlayer thickness due to the low film compactness and high electrical conductivity.

Evaluation of cereal forage grasses and forages from them according to the content of protein insoluble in acid detergent

The nitrogen content was determined in acid-detergent fiber (ADF) isolated from awnless rump, meadow fescue and meadow timothy, depending on the phase of their the same phases are for silage and haylage. Samples for analyzes were dried at a temperature of 60-65 ° C. As the grasses grew, an increase in the content of CDC in them was observed, which was also accompanied by an increase in ADF from the phase of entering the tube to flowering in timothy grass - from 1.18 to 1.36%, in meadow fescue - from 0.96 to 1.58 5%. When preserving grasses, an increase in the content of CDC is observed in all phases of their growth as compared to the original grass, but the mass fraction of ADF in the dry matter of silage and haylage was no more than in the original grass. If the technology of harvesting silage and haylage is observed, the level of thermal damage to these forages does not increase. With the growth of grasses from the vegetative phase to flowering, the content of SP in grasses and forages from them decreases, while the proportion of ADF in it increases. The inverse relationship between these indicators had correlation coefficients of 0.83, 0.88 and 0.92 for grasses, silage and haylage, respectively. The need to harvest them in earlier phases of growth is noted.

Deposition of ultrananocrystalline diamond at low temperature using CO, CH4 mixed carbon source

UNCD (Ultrananocrystalline diamond) is a material with various excellent properties, but the high deposition temperature limits its application. UNCD was deposited at low temperature (700 K) using CO–CH4–H2-Ar as gas source. CO as reaction gas reduces the activation energy of CH4 system. The effects of different H2 concentrations on the morphology of diamond films were studied. The results show that ultra-nanocrystalline films can be deposited by CO–CH4–H2-Ar. The morphology of UNCD film can be observed by SEM images from dense film to needle film and then to spherical clusters. With the increase of H2 concentration, sp2 content decreased, and a-C:H appeared, and a-C:H increased first and then decreased. Analysis of OES(optical emission spectra) showed that the content of C2 under mixed carbon source was higher than that of single carbon source, and the change of CH390 was related to the formation of a-C:H. The optical properties of the film were tested, and the maximum transmittance was 88.9%.

Effect of electron irradiation on polypropylene and polystyrene foils studied by pattern recognition methods on electron spectroscopy data

ABSTRACT Degradation of polypropylene (PP) and polystyrene (PS) surfaces under electron beam in ultra-high vacuum is studied by electron spectroscopy, pattern recognition, and atomic force microscopy. Effects on hydrogen, carbon sp2/sp3 content, and microstructure are quantified and correlated. Electron irradiation at 1500 eV causes hydrogen and C sp3 content decrease and surface morphology modification. Roughness changes from 29 to 15 nm on PP, whereas it remains 5 nm on PS. Decreasing C sp3 content in PP, contrary to PS, indicates C–H, C–C bonds scission and carbonization. Cross-linking predominates over carbonization in PS, confirming its better stability, in agreement with surface morphology data.

On the Application of Electron Energy-Loss Spectroscopy for Investigating Nanostructure of Soot from Different Fuels

Soot is characterized by a multiscale structural organization; the only diagnostic tool that can give access to it is the transmission electron microscope (TEM). However, as it is a diffraction-based technique, TEM images only conjugate aromatic systems and, thus, it is particularly useful to combine it with electron energy-loss spectroscopy (EELS), which is able to provide quantitative information about the relative abundance of sp3 and sp2 hybridized carbon. In this paper, a method for the EELS spectrum analysis of carbonaceous materials, recently developed for electron-irradiated graphite and glassy carbon composition analysis, has been applied for the first time on soot samples, in order to test its performance in soot nanostructure study in combination with TEM and high-resolution TEM (HRTEM). Soot samples analyzed were collected in the soot inception region of premixed flames of different hydrocarbon fuels. EELS, in agreement with TEM and HRTEM, showed a quite disordered and heterogeneous structure for young soot, with a relatively low sp2 content and slight presence of fullerene-like structures, more evident in the case of methane soot hinting to the effect of more saturated aliphatic fuels on soot characteristics at soot inception.

Analysis proximate of sargassum seaweed sp

Sargassum sp. seaweed becomes one of the interesting food preparations for the community and can be a potential local food-based product because this type of brown seaweed can be processed into food, pharmaceutical, cosmetic, and textile products. Seaweed Sargassum sp. has economic value and protection for marine life. Sargassum sp can be beneficial in the health field because it contains protein, minerals, alginates, active compounds of steroids, alkaloids, and phenols that function as antibacterial, antifungal, and antiviral properties. Sargassum sp., was the largest class of brown algae (Phaeophyta) in tropical seas. The purpose of this study was to determine the nutritional composition of Sargassum sp. which includes protein content, fat content, ash content, and water content. The method used is a proximate analysis method based on SNI 01-2354.4-2006, SNI 2891 01 1992, SNI 01-2354.1-2006, and SNI 2354.2: 2015. The results obtained were Sargassum sp protein levels of 3.048% higher than E. cottonii. Fat content in Sargassum sp of 0.617% of dry weight is lower than E. cottonii. The ash content of Sargassum sp was 7.112% higher than that of E. cottonii in proportion to the mineral content of the two seaweeds. The water content of Sargassum sp was 67.281% lower than E. cottonii, both of which were higher than the specified water content standard of <32%. This is also influenced by the drying process. Conclusion: Sargassum sp has good content to be consumed and used as local food products.

Electrochemical Detection of Tryptophan Metabolites via Kynurenine Pathway by Using Nanocarbon Films

AbstractWe studied nanocarbon film electrodes with the aim of detecting tryptophan metabolites via the kynurenine pathway. The nanocarbon films were formed by using unbalanced magnetron sputtering, and they exhibited superior electrode properties including a wide potential window and a low background current as a result of the sp3‐containing structure and ultraflat surface. These properties allowed us to detect certain tryptophan metabolites such as kynurenic acid (KYNA), which has a relatively high oxidation potential. We also investigated the effect of the sp2/sp3 ratio of the nanocarbon film as regards the electrode activity in relation to target molecules. We found that the sp2/sp3 ratio played important roles in both widening the potential window and obtaining superior electrode performance for the metabolites. The nanocarbon film with a high sp3 content was beneficial as regards the electrode performance with respect to the detection limit and sensitivity. Compared with conventional carbon‐based electrodes, the nanocarbon film electrode with a high sp3 content exhibited higher electrode activity against KYNA while maintaining a low background current. Computational experiments revealed that the theoretical oxidation potential (Eox) value for some targets coincided with that obtained in electrochemical experiments using our nanocarbon film electrode.

Effects of temperature and pH on biochemicals content of microalgae Monoraphidium sp.

The production of secondary metabolites varies under the different environmental conditions. The aim of this study was to investigate the effects of pH and temperature on the content of antioxidant compounds in a species of microscopic algae. First, the microalgal strain Monoraphidium sp. was cultured under the different temperature and pH treatments. The biochemical assays were then performed on the compounds such as photosynthetic pigments, phenolic compounds, and total flavonoids. The total antioxidant activity was evaluated by FRAP and DPPH methods. The results of this study showed that the microalgae Monoraphidium sp. had the maximum growth and high content of antioxidant compounds at the acidic pH and temperature 28°C. The results indicated that the optimal conditions can be achieved for the high production of antioxidant compounds in microalgae by changing the environmental factors, which can be used in the pharmaceutical, medical, and production of nutritional supplements industries.