Substrate Preparation Research Articles

Effect of Stainless Steel Substrate Preparation on the Adhesion Strength and Morphology of Electrophoretically Deposited Sodium Alginate Coatings

In this study, the influence of various mechanical and chemical surface treatments on the adhesion strength and surface properties of sodium alginate coatings electrophoretically deposited (EPD) on 316L stainless steel substrates was investigated. XPS and TEM results revealed the presence of oxide layers containing elements from the substrates, with thicknesses varying from 1 to 45 nm, depending on the treatment used. Most substrates exhibited high roughness and hydrophilic properties (CA with water 62.8–82.6 deg). Sodium alginate coatings with uniform morphology were deposited with the same process parameters, i.e., 5 V and 300 s. The surface topography of the coatings was closely related to that of the substrate on which they were deposited. All coatings exhibited higher hydrophilicity (CA with water 29.5–49.7 deg) compared to the substrates (CA with water 62.8–82.6 deg). The coatings on the etched and anodized substrates demonstrated the highest adhesion strength (class 4B), attributed to the very low oxide layer thickness and the specific substrate surface topography. Mechanical interlocking was identified as the primary adhesion mechanism for these coatings. This work provides insight into optimizing surface treatments for improved adhesion of sodium alginate coatings to stainless steel substrates widely used for temporary bone implants. The results obtained will also be helpful in providing high adhesion of sodium alginate-based composite coatings to steel substrates.

Synthesis and Characterization of Cobalt-doped Titanium Dioxide Thin Films as Solar Cell Components using UV-SEM Analysis

Research has been carried out in the form of the synthesis and characterization of thin films of titanium dioxide with the addition of cobalt doping. The purpose of this research was to synthesize and characterize thin films related to optical properties, morphological shapes, and components of thin film compounds that are good for use as basic materials for the development of nanoparticle technology in the form of solar cells. The research was carried out in two stages, namely synthesis such as preparation of glass substrates, preparation of sol-gel solutions, deposition of solutions onto glass substrates, and heating of TiO2:Co thin film samples. The next stage is the thin film characterization test, where the optical properties of the thin film, such as absorbance, transmittance, gap energy, and activation energy, are measured using a UV-vis spectrophotometer, while morphological data and components of the thin layer compounds are measured using a Scanning Electron Microscope-Energy Dispersive X-rays (SEM-EDX). Based on data analysis and discussion, it was found that the optical properties, such as the transmittance value of the thin film, experienced the lowest point at a wavelength of 250–280 nm with a maximum percentage value of 62.14 to 78.85%. The greater the doping concentration, the lower the transmittance value. This condition is inversely proportional to the absorbance value of the maximum TiO2:Co thin film, which is in the region with a wavelength of 280–300 nm and a value of 5.70–6.31. The greater the doping concentration, the greater the absorbance value. The energy bandgap values of TiO2:Co thin films for doping concentrations (0, 5, 10, 15, 20)% were 3.44; 3.39; 3.38; 3.32; 3.22 eV for the direct energy bandgap and 3.86; 3.85; 3.84; 3.85; 3.82 eV for the indirect energy gap. The activation energy of the TiO2:Co thin film decreased from 2.86 to 2.26 eV. As for the morphological data of the TiO2:Co thin film, it was found that the greater the concentration of doping, the layer was deposited evenly, finely, and homogeneously. Regarding the data on the components of the thin layer compounds, it was found that the percentage of TiO2 content was in the range of 64.48–95.94%, while for Co, it was in the range of 0.00–19.21%.

Robust and Irreversible Sortase-Mediated Ligation by Empolyment of Sarkosyl.

Sortase-mediated ligation (SML) is a widely used method for peptide and protein ligation due to ease of substrate preparation and fast enzymatic kinetics. But there are drawbacks that limit broader applications. Sorting motif in substrates may not be exposed to sortase efficiently due to folding or aggregation. In addition, the ligation is reversible under transpeptidation equilibrium that restricts ligation yield. Here we report a simple but robust method to overcome such limitations. By employment of sarkosyl, the detergent alters substrate conformation to raise sorting motif accessibility for sortase catalysis. Moreover, transpeptidation becomes irreversible presumably by formation of micelle to shield ligation products from sortase. In consequence, excellent yields were achieved from sortase variants with different substrate specificity. Notably, this method is compatible with peptides or proteins capable of forming liquid-liquid phase separation (LLPS), presenting a powerful approach for the conjugation of aggregation-prone substrates. Therefore, we believe the sarkosyl-enhanced SML could be widely applied in peptide and protein chemistry and the unique irreversible transpeptidation mechanism offers an insight to detergent-driven equilibrium.

ОПРЕДЕЛЕНИЕ ФИТОТОКСИЧНОСТИ СУБСТРАТОВ НА ОСНОВЕ ОТХОДОВ АКТИВНОГО ИЛА В ВЕГЕТАЦИОННЫХ ОПЫТАХ

The aim of the study is to determine the phytotoxicity of components and substrates using waste from the treatment facilities of the Arkhangelsk Pulp and Paper Mill. The substrates were made on the basis of high-moor peat with a decomposition degree of 15 %, with the addition of Biohumus Arkhangelsky, which is composted residual activated sludge from treatment facilities (RAS). To test extracts from materials used to prepare experimental substrates, oats (Avena sativa L.) and watercress (Lepidium sativum L.) were used. Comparison was carried out with distilled water and Knop's mixture. To select the optimal ratio of residual activated sludge and peat for plant growth, a model experiment was conducted with growing oats. The substrates prepared by the volume of fractions with a gradation of activated sludge of 10 % were studied. It was found that composted activated sludge does not have phytotoxicity in relation to the test objects. The extract based on dewatered activated sludge of the treatment facilities of the Arkhangelsk Pulp and Paper Mill does not have a depressing effect on the germination of test objects – oat and watercress seeds, and according to the indicators of the length of the root and coleoptile of oats, it has a stimulating effect comparable to or exceeding the effect of the Knop mixture. Phytostimulating effect of peat extract was not detected. The addition of OAI to high-moor peat during the preparation of substrates has a positive effect on growth indicators. An increase in the length of the stem and root, the mass of the underground and aboveground parts of plants is noted. The optimal addition to the substrate for growing oats is composted activated sludge in the amount of 10–20 %. With large proportions of composted activated sludge waste (more than 40 %), oat growth decreases, but the mass of stems and roots increases.

Utilization of local agro-industrial by-products based substrates to enhance production and dietary value of mushroom (P. ostreatus) in Ethiopia

Food insecurity and malnutrition are serious problems in many developing countries, including Ethiopia. This situation warrants an urgent need for the diversification of food sources with enhanced productivity. This study was aimed at contributing to the food security in Ethiopia through cultivation of Pleurotus ostreatus mushrooms using sustainable and locally available agro-industrial byproduct-based substrates in parallel with pollution control. Ten substrates were prepared using sugarcane bagasse, filter cake, trash, cotton seed hull and animal waste, namely cow dung and horse and chicken manure. The effect of each substrate (treatment) on the yields, biological efficiency, nutritional composition, and mineral contents of Pleurotus ostreatus mushroom species was evaluated at the Ethiopian Forest Products Innovation Center, Addis Ababa, Ethiopia. The results obtained indicate that a significantly higher (p < 0.05) yield and biological efficiency were recorded from the mushroom cultivated on S2 substrate containing a mixture of 80% sugarcane bagasse, 12% cow dung, and 8% cotton seed hull. Moreover, substrate containing sugarcane bagasse mixed with cotton seed hull, cow dung, and chicken manure significantly (p < 0.05) increased the yields and biological efficiency of the mushroom. The content of protein, crude fat, fiber, and carbohydrates of the mushroom cultivated from all the utilized substrates were in the range of 17.30–21.5, 1.77–2.52, 31.03–34.38, and 28.02–39.74%, respectively. The critical macro-elements are abundant in the mushroom in the order of potassium, magnesium, calcium, and sodium. The mushrooms cultivated on all the substrates were rich in essential micro-elements in the order of iron and zinc. It was found that substrate preparation and formulation significantly (p < 0.05) improved the yields, biological efficiency, nutritive values, and mineral contents of the mushroom. The use of these by-products as substrates is sustainable and environmentally friendly and allows the production of mushroom with high nutritional value on a sustainable basis in order to enhance food security in the country.

Multi-Colored Aqueous Ink for Rewritable Paper.

As sustainable and eco-friendly replacements to conventional paper, rewritable paper is a very attractive alternative for communication, information circulation, and storage. Development is made for rewritable paper using chromogenic materials that change its color in presence of external stimuli. However, the new techniques have faced several major challenges including feasible operational method, eco-friendly approach. Herein, a simple, convenient, and eco-friendly strategy is described for the preparation of rewritable paper substrate, and multi colored ink for efficient use in writing, painting or printing purpose. In addition, writing with "invisible ink" on the rewritable paper can be realized for potential anti-counterfeiting application. The written, painted, or printed information on the paper substrate can be easily erased using an aqueous solution. Thus, the original paper can be retrieved and the paper substrate can be reused multiple times. Besides, the written or printed information can be retained for a prolonged time at ambient conditions. Overall, this approach shows the rewritable paper as a prototype of multicolor writing/painting application, offering a sustainable solution for reducing paper waste and promoting environmental stewardship.

Iron(III)-Catalysed Povarov Cyclisation for the Synthesis of Fused Dibenzo[b,f][1,7]naphthyridine Embedded Arylpyrrolo Scaffolds

AbstractAn FeCl3-catalyzed Povarov reaction for the efficient synthesis of dibenzo[b,f][1,7]naphthyridines utilizing 1-(2-alkynylaryl)-2-pyrrolecarbaldehydes and arylamines in excellent yields is demonstrated. The essential features of the present strategy are easy preparation of substrates, broad substrate scope, mild reaction conditions, and high atom economy and yields, in the presence of environmentally friendly iron catalysis.

Influence of Vermicompost on the Concentration of Exogenous Indole-3-Acetic Acid and Its Effect on the Development of Tomato Plants (Lycopersicum esculentum L.)

Indole-3-acetic acid (IAA) concentration is directly proportional to the amount of vermicompost (VC) added to sand substrates. The objectives of this work were to establish the effect of the amount of VC in sand substrates on the concentration of IAA and to determine its influence on tomato plants. Sand substrates with VC percentages (0, 20, 40, and 50%) were placed in pots; in each one, the concentration of IAA was determined at the beginning and the end (after supporting tomato plants), and its bacterial load was determined. In tomato plants, some vegetative and yield components were measured. The results show that by adding 1 kg of VC in a sand-based substrate, the concentration of exogenous IAA increases by 0.0470 and 0.0642 mg g−1 (at the beginning and the end, respectively). This increase was reflected in the development of the plants; for example, their roots demonstrated their maximum development (370.20 cm−3) when the amount of VC in the substrate was 3.95 kg. Therefore, the amount of VC used in the preparation of substrates influences the concentration of IAA in them, which is reflected in the development of tomato plants.

Application of Organo-Modified Silica Nanoparticles to Improve the Load-Bearing Capacity of Bonded Joints of Dissimilar Steel Substrates

The paper deals with the joining of dissimilar steels by adhesive bonding. The base materials for the experimental work were deep-drawn low-carbon steel DC04, and hot-dip galvanized HSLA steel HX340LAD+Z. Adhesive bonding was performed using rubber-based and epoxy-based adhesives. The research aimed to verify the importance of surface preparation of steel substrates using a formulation with organically modified silica nanoparticles and epoxy organic functional groups, where one end of the functional group can be incorporated into the organic binder of the coating material and the other end can be firmly bonded to substances of an inorganic nature (metals). Since the binder base of adhesives is very similar to that of coatings, verifying the performance of this surface preparation when interacting with the adhesive is necessary. The load-bearing tensile shear capacity of single-lapped joints and the resistance of the joints against corrosion-induced disbanding in a climate chamber were tested. The energy dissipated by the joints up to fracture was calculated from the load-displacement curves. Bonded joints with organosilane were compared with joints without surface preparation and joints prepared by chroman-free zirconate passivation treatment. Exposure of the joints in the climatic chamber did not cause a relevant reduction in the characteristics of the joints. Organosilicate formulation was proved effective when bonding ungalvanized steels with a rubber-based structural adhesive, where it improves the bond quality between the adhesive and the substrate.

Design and preparation of woven fabric-reinforced substrate: A new pathway for robust thin film composite membrane

The thin film composite (TFC) membrane possesses the highest commercial application potential among all types of forward osmosis (FO) membranes. The support layer of the membrane plays a crucial role in both bearing mechanical loads and facilitating the active layer formation. Herein, we addressed the issues of low permeability and poor mechanical strength of the conventional TFC FO membrane by selecting suitable fabrics and optimizing membrane design and preparation. Polyester (PS) woven fabric, with its high strength, low thickness, and high porosity, served as an excellent material for reinforcing the strength of the FO membrane. We employed a novel double-blade casting method to address the defect issue associated with the conventional single-blade casting method. The influencing factors and quality control strategies of the fabric-reinforced substrate were systematically investigated. Furthermore, membrane characterization techniques, including scanning electron microscopy (SEM), liquid-liquid displacement porometer, and cross-flow FO system, were used to reveal the influences of different substrates, including polysulfone (PSU), polyacrylonitrile (PAN), and polyetherimide (PEI), on the structure and performance of the fabric-reinforced TFC-FO membrane. Compared to commercial FO membranes, the TFC/PSU membrane exhibited superior FO performance, with a water flux of 24.1 LMH, and outstanding mechanical strength that was more than 10-times higher than that of free-standing membranes. This study demonstrates a new pathway for engineering robust TFC-FO membranes with low structural parameters as well as excellent scalability of the membrane fabrication method.

A Review Delving into the Factors Influencing Mycelium-Based Green Composites (MBCs) Production and Their Properties for Long-Term Sustainability Targets.

Mycelium-based green composites (MBCs) represent an eco-friendly material innovation with vast potential across diverse applications. This paper provides a thorough review of the factors influencing the production and properties of MBCs, with a particular focus on interdisciplinary collaboration and long-term sustainability goals. It delves into critical aspects such as fungal species selection, substrate type selection, substrate preparation, optimal conditions, dehydrating methods, post-processing techniques, mold design, sterilization processes, cost comparison, key recommendations, and other necessary factors. Regarding fungal species selection, the paper highlights the significance of considering factors like mycelium species, decay type, hyphal network systems, growth rate, and bonding properties in ensuring the safety and suitability of MBCs fabrication. Substrate type selection is discussed, emphasizing the importance of chemical characteristics such as cellulose, hemicellulose, lignin content, pH, organic carbon, total nitrogen, and the C: N ratio in determining mycelium growth and MBC properties. Substrate preparation methods, optimal growth conditions, and post-processing techniques are thoroughly examined, along with their impacts on MBCs quality and performance. Moreover, the paper discusses the importance of designing molds and implementing effective sterilization processes to ensure clean environments for mycelium growth. It also evaluates the costs associated with MBCs production compared to traditional materials, highlighting potential cost savings and economic advantages. Additionally, the paper provides key recommendations and precautions for improving MBC properties, including addressing fungal strain degeneration, encouraging research collaboration, establishing biosecurity protocols, ensuring regulatory compliance, optimizing storage conditions, implementing waste management practices, conducting life cycle assessments, and suggesting parameters for desirable MBC properties. Overall, this review offers valuable insights into the complex interplay of factors influencing MBCs production and provides guidance for optimizing processes to achieve sustainable, high-quality composites for diverse applications.

Technical note: Optimization of the preparation of cascade impactors collection substrates for airborne metallic ultrafine particle sampling

The characterization of workers’ exposure to airborne metallic ultrafine particles (UFP) has been an increasing issue because of their effects on health, and as many activities are potentially concerned such as welding, oxy-cutting or 3D printing. Determining the particle size distribution of such an aerosol provides a real contribution to the understanding of UFP exposures and associated health effects, as it is directly related to their penetration in the respiratory tract. In this context, it is proposed to optimize the preparation of collection substrates of cascade impactors of airborne metallic UFP. The experimental results confirm that the collection substrates have to be prepared beforehand by coating them with a high-vacuum-resistant silicone grease. The results highlight that this grease has to be preliminarily dissolved in a heptane-based solution with a mass ratio grease-solvent of 7.5%, and then deposited on the substrate with a target height of 9 μm. Applying this protocol ensures a reproducible and representative determination of the particle size distribution, allowing the phenomena of particle bouncing and reentrainment to be significantly reduced. It is also shown that coated collection substrates remain stable for several months in terms of mass, and that the samples collected remain stable during transport thanks to the improvement of particle cohesion on the coated membrane.

GO and surfactant assisted regulation of polyamide nanofiltration membranes for improved separation performance

Fabricating nanofiltration membranes with high water permeance and selectivity by tailoring the structure and morphology is crucial to efficient water purification. In this work, the fabrication of thin film nanocomposite (TFN) nanofiltration membranes by combining two methods, the surfactant-assembly interfacial polymerization (SARIP) and the addition of graphene oxide (GO) or ionic liquid functionalized graphene oxide (GO-IL) for the preparation of the selective PA layer on a novel porous substrate is reported. For the preparation of the porous substrate, mechanically robust, aromatic polyethers containing polar pyridine units (PDSPP) were chosen targeting to improved hydrophilicity and thus enhanced water permeability. The anionic sodium dodecyl sulfate (SDS) surfactant was used to regulate the interfacial polymerization thereby enabling the formation of dense PA layers with high cross-linking degree and consequently high salt rejections. On the other hand, the addition of GO/GO-IL nanosheets could impart hydrophilicity and antifouling properties. The novel porous PDSPP substrate was selected for the fabrication of TFN membranes due to its improved water permeability and superior salt rejection and increased hydrophilicity compared to commercial PSf substrate. The detailed study of the fabricated TFN membranes by ATR-FT-IR, SEM, AFM, XPS, contact angle measurements revealed the formation of polyamide selective layers with rougher surfaces, increased hydrophilicity and high cross-linking degrees (from 44 % to 94 %), resulted from the synergistic effect of SDS and GO incorporation. Moreover, the prepared TFN membranes exhibited high salt rejections while maintaining a moderate water permeability. In particular, the membrane containing the neat GO (TFNGO50) displayed excellent Na2SO4 and MgSO4 rejections (98.8 % and 99.5 %, respectively) while the NaCl rejection was 47.0 % and a water permeability value of 4.2 L m-2h−1 bar−1. The divalent salt rejections were among the highest values reported in the literature in comparison with commercial NF membranes and TFN membranes containing GO/functionalized GO. When GO-IL nanosheets were embedded in the PA layer, the water permeability was slightly improved while the salt rejections were significantly reduced compared to TFNGO50. Lastly, the incorporation of GO enhanced the anti-fouling properties of the prepared membranes due to increased hydrophilicity of the PA surface.

A Novel Multiarmed Bifunctional PEG Derivative for the Preparation of Mass Spectrometry Ion Sources with Antifouling Property and High Selectivity.

It is challenging to prepare a highly selective mass spectrometry (MS) ion source for the rapid and highly sensitive detection of analytes, especially mycotoxins. In this study, an amino and tetrazine bifunctionalized multiarm PEG derivative (NH2HCl-4armPEG10K-(MTz)3), which can be easily immobilized on the substrate by the addition reaction between amino and polydopamine, was used for the preparation of MS ionization substrate. NH2HCl-4armPEG10K-(MTz)3 can also be used as a linker to immobilize sufficient streptavidin (SA) on the surface of the substrate by a click reaction. The process further promotes the immobilization of broad-spectrum antibodies (3D4), which were used as the recognition element for ZEN and its metabolites. The prepared SSS-Au-PDA-4armPEG10K-SA-3D4 not only can rapidly enrich ZEN and its metabolites with high selectivity but also shows good antifouling properties in the matrix. After simple sample preparation, the prepared SSS-Au-PDA-4armPEG10K-SA-3D4 can be directly coupled with MS to achieve high sensitivity (LODs: 0.18-0.66 ng/mL, LOQs: 0.5-1.0 ng/mL) and selective detection of ZEN and its metabolites in the matrix. At the same time, satisfactory recoveries (83.60-97.80%) and precision (RSD: 2.80-9.10%) can also be obtained. The prepared SSS-Au-PDA-4armPEG10K-SA-3D4 is expected to provide a powerful tool for the rapid and highly sensitive determination of multiple targets by MS.

Pre- and Postharvest Strategies for Pleurotus ostreatus Mushroom in a Circular Economy Approach.

Mushroom cultivation presents a viable solution for utilizing agro-industrial byproducts as substrates for growth. This process enables the transformation of low-economic-value waste into nutritional foods. Enhancing the yield and quality of preharvest edible mushrooms, along with effectively preserving postharvest mushrooms, stands as a significant challenge in advancing the industry. Implementing pre- and postharvest strategies for Pleurotus ostreatus (Jacq.) P. Kumm (oyster mushroom) within a circular economy framework involves optimizing resource use, minimizing waste, and creating a sustainable and environmentally friendly production system. This review aimed to analyze the development and innovation of the different themes and trends by bibliometric analysis with a critical literature review. Furthermore, this review outlines the cultivation techniques for Pleurotus ostreatus, encompassing preharvest steps such as spawn production, substrate preparation, and the entire mushroom growth process, which includes substrate colonization, fruiting, harvesting, and, finally, the postharvest. While novel methodologies are being explored for maintaining quality and extending shelf-life, the evaluation of the environmental impact of the entire mushroom production to identify areas for improvement is needed. By integrating this knowledge, strategies can be developed for a more sustainable and circular approach to Pleurotus ostreatus mushroom cultivation, promoting environmental stewardship and long-term viability in this industry.

Diamond-like carbon conversion surfaces for space applications

We present diamond-like carbon (DLC) conversion surfaces to detect particles with energy below 2 keV. Conversion surfaces have been widely applied in measurements of low-energy particles by instruments onboard planetary and heliophysics missions. Their effectiveness is characterized by the efficiency in changing the charge state of the incident particles while maintaining a narrow angular distribution for the reflected particles. DLC as a conversion surface coating material has high conversion efficiency. We developed a conversion surface production process that provides ultra-smooth and ultra-thin DLC conversion surfaces. The process includes substrate preparation through precision cleaning, plasma immersion ion deposition of the DLC film, and diagnostics of the film parameters. The latter includes the measurement of the coating thickness, surface roughness, and the conversion efficiency for ion beams with energy below 2 keV. The process we developed provides the DLC conversion surface coating of repeatable parameters with a mean surface roughness of 3.4 ± 0.2 Å and a mean film thickness of 46.7 ± 0.8 nm uniform across the sample area. Ion beam measurements showed a negative ion yield of 1%–2% for hydrogen atoms and 8%–15% for oxygen atoms with an angular scatter distribution of 10°–20° at full width of half maximum. These results agree with those of other conversion surface coatings in the literature. The DLC conversion surfaces presented here are implemented in the conversion surface subsystem of the Interstellar Mapping and Acceleration Probe (IMAP)-Lo instrument of the IMAP mission scheduled for launch in 2025.

Bioproduct advances: insight into failure factors in mycelium composite fabrication

AbstractIn the evolving field of bioproducts, materials that synergize sustainability with functionality are of paramount importance. Mycelium composites, derived from intricate networks of fungal filaments, are gaining traction as innovative bioproducts that offer a compelling blend of eco‐friendliness, renewability, and adaptability. As the quest intensifies for alternatives that can mitigate the environmental toll of conventional products, mycelium‐based solutions are emerging as beacons on the sustainable bioproducts horizon. Their transition from niche innovations to mainstream applications depends on their ability to overcome a series of fabrication challenges. This review paper investigates the critical challenges faced in the fabrication of mycelium composite. It examines rigorously some essential factors leading to fabrication failure, such as contamination, inconsistent growth, insufficient moisture, inappropriate pH, and improper substrate preparation. The review offers a comprehensive analysis of each factor influencing mycelium growth and the resulting composite properties, with an emphasis on preventative and mitigating strategies. Through an in‐depth exploration of case studies detailing unsuccessful mycelium composite fabrication, the significance of understanding these failure factors is emphasized. The paper culminates in a forward‐thinking discourse on potential strategies for refining fabrication processes, and identifies promising research areas poised to enhance both the success rate and overall efficiency of mycelium composite production.

Enhancing fire resistance of masonry structures: The potential of ultra high performance concrete (UHPC)

The potential of ultra high performance concrete (UHPC) for strengthening masonry structures is evaluated in this work, both under normal service conditions and after exposure to high temperatures, as a significant gap has been identified on this topic at the present time. The mechanical properties of UHPC exposed up to 800 °C are analyzed by means of destructive and non-destructive tests, and the UHPC-to-masonry bond capacity is tested, depending on temperature and substrate preparation. The strengthening of masonry columns by confinement is studied, proving that UHPC jackets can double the compressive strength and provide ductility, even after exposure to high temperatures. Strengthening of masonry walls to in-plane loads is also evaluated, finding that UHPC layers can increase the shear strength and prevent brittle failures. Experimental results are compared with the predictions of theoretical models from some design guides, slightly adapted to the context of this research, obtaining a good degree of accuracy.

Evidence of gas phase nucleation of nanodiamond in microwave plasma assisted chemical vapor deposition

The mechanism of ballas-like nanodiamond formation still remains elusive, and this work attempts to analyze its formation in the framework of activation energy (Ea) of nanodiamond films grown from a H2/CH4 plasma in a 2.45 GHz chemical vapor deposition system. The Ea was calculated from the Arrhenius equation corresponding to the thickness growth rate using substrate temperature (∼1000−1300 K) in all the calculations. While the calculated values matched with the Ea for nanodiamond formation throughout the literature, these values of ∼10 kcal/mol were lower compared to ∼15–25 kcal/mol for standard single crystal diamond (SCD) formation, concluding thus far that the energetics and processes involved were different. Further, the substrate preparation and sample collection method were modified while keeping the growth parameters constant. Unseeded Si substrate was physically separated from the plasma discharge by a molybdenum disk with a pinhole drilled in it. Small quantity of a sample substance was collected on the substrate. The sample was characterized by electron microscopy and Raman spectroscopy, confirming it to be nanodiamond, thus suggesting that nanodiamond self-nucleated in the plasma and flowed to the substrate that acted as a mere collection plate. It is hypothesized then, if nanodiamond nucleates in gas phase, gas temperature has to be used in the Arrhenius analysis. The Ea values for all the nanodiamond films were re-calculated using the simulated gas temperature (∼1500−2000 K) obtained from a simple H2/CH4 plasma model, giving new values within the range characteristic to SCD formation. Based on these findings, a unified growth mechanism for nanodiamond and SCD is proposed, concluding that the rate-limiting reactions for nanodiamond and SCD formation are the same.

A process to reproduce repeatable 2D material-based hierarchical enhanced surface area structures

We report a repeatable method for fabrication of a 2D material-based hierarchical enhanced surface area structures (HESAS), which relies on a titanium substrate as the base for nucleation and growth and a titania-acid solution. Since the initial documentation of these formations in 2020, numerous experimental iterations have ensued, culminating in the establishment of a straightforward, replicable procedure for their fabrication. Subsequent to the inaugural report, this manuscript offers a comprehensive overview of the synthesis procedure and structural attributes. Furthermore, it summarizes various pivotal discoveries attained during the course of process refinement, including the significance of substrate preparation in particle synthesis. Specifically, the removal (or lack thereof) of the oxide layer dictates whether (or not) the 2D building blocks form, which corroborates that the composition and level of reactivity of the base surface—where the heterogenous nucleation events take root—appear to impact the ability for crystallization to occur. Nonclassical nucleation and crystallization theories could explain some of the observed patterns in the fabricated HESAS. This report briefly discusses some of the factors which affect supersaturation for the chosen synthesis system and the critical role supersaturation plays in the development of HESAS. Future work should include advancing understanding on the kinetics (and hence dynamic behavior) of the supersaturation parameters; this will be critical to develop controlled fabrication protocols of HESAS, enabling their broader adoption.