Substrate Preparation Research Articles

A Tuneable and Easy-to-Prepare SERS Substrate Based on Ag Nanorods: A Versatile Tool for Solution and Dry-State Analyses

Surface-enhanced Raman spectroscopy is a powerful technique for the ultra-sensitive detection of organic analytes. In this paper, the preparation of SERS substrates based on silver nanorods (AgNRs) is proposed, exploiting a simple protocol which does not require complex procedures and/or sophisticated and expensive instrumentation. For this purpose, various syntheses of AgNRs were tested, and the best one for preparing the SERS active substrate proved to be the one which does not involve surfactants as nanoparticle stabilizers. The plasmonic properties of the selected substrate can be modified based on the concentration of the deposited nanoparticles, allowing for the experimentation of different excitation wavelengths. Positive results were obtained on reference solutions of three natural dyes of historical interest using both green exciting radiation (532 nm) and two near-infrared ones (785 and 850 nm; the latter is combined with the SSE™ technology for further fluorescence quenching). Furthermore, the substrates of AgNRs were found to be suitable for SERS measurements even in dry-state conditions, i.e., only exploiting the electromagnetic interaction between the nanostructured substrate and the dye molecules absorbed onto a wool fibre.

Band Alignment and Surface Photo-Voltage Analysis of C-Si/Siox/Poly-Silicon Passivating-Contact Stacks Through X-Ray Photoelectron Spectroscopy.

Ultrathin SiOx layers and c-Si/SiOx interfaces find application in tunnel-oxide passivated contacts (TOPcon) for high-efficiency silicon solar cells. Here, we investigate their detailed microscopic properties, with specific attention for the case of c-Si(100) substrates, capped either by p-type or n-type poly-silicon layers [c-Si/SiOx/poly-Si (p+) or c-Si/SiOx/poly-Si (n+)]. Our focus is on the effects of the substrate preparation conditions (either by a dry-plasma or wet SiOx process) and the high-temperature annealing step (as required for the poly-Si crystallization) on the SiOx stoichiometry and its microscopic structure. Through advanced photoemission techniques, we find a clearly decreased valence band offset between the c-Si and SiOx (from 4.5 eV to 4.15 eV) when comparing the dry SiOx with the wet SiOx process, independent of the SiOx film thickness, but correlating with the relative fraction of sub-stochiometric Si states. We lastly examine the magnitude of band-bending of the contact structure through controlled in-situ exposure to light of the surfaces and subsequent tracking of core and valence band levels via a surface photovoltage and a junction photo-voltage (JPV) effect. By analyzing this JPV effect qualitatively, we find it to be proportional to the expected quasi fermi level splitting within the c-Si wafer.

Twin-free thermal laser epitaxy of Si on sapphire

The heteroepitaxial growth of silicon (Si) is essential for modern electronics. Our study investigates the potential of thermal laser epitaxy (TLE) for Si epitaxy. A systematic study on the evaporation behavior of Si during TLE identifies and addresses the causes of notable flux rate fluctuations, resulting in a Si flux with ±0.3% stability over time. We also demonstrate heteroepitaxy of Si on c-plane sapphire substrates via TLE. High-temperature substrate preparation combined with deposition at a substrate temperature of 1000 °C produced high-quality epitaxial Si (111) films without twin domains.

Optimization of Manure-Based Substrate Preparation to Reduce Nutrients Losses and Improve Quality for Growth of Agaricus bisporus

With the growing world population, food demand has also increased, resulting in increased agricultural waste and livestock manure production. Wheat straw and cow dung are rich nutrient sources and, if not utilized properly, may lead to environmental pollution. Keeping in view the cultivation of Agaricus bisporus on straw/manure-based substrate, the current study aimed to optimize the conventional manure preparation technique to reduce nutrient losses and keep the quality of manure at its best. The treatments were considered as traditional and optimized schemes for mushroom substrate preparation. The results achieved herein indicated that the nutrient losses were low in the optimum scheme. For carbon (C), the loss was 43.55% at the substrate stage in the traditional scheme and reduced to 37.75% in the optimum scheme. In the case of nitrogen (N), the loss was 22.01% in the traditional scheme and was lower (18.49%) in the optimum scheme. The nutrient concentration in Agaricus bisporus was higher with the optimum scheme compared with the traditional scheme. It was 1.74% for C, 7.17% for N, 3.58% for phosphorus (P), and 4.92% for potassium (K). The optimum scheme also improved the Agaricus bisporus yield per unit area (84.55%) and the total yield (28.92%). The net income of the optimum scheme was 102.95% higher compared to the traditional scheme. The economic analysis also revealed that the benefit–cost ratio of the optimum scheme was high (48.86%) compared with the traditional scheme. This study concludes that the use of the optimum scheme can better utilize the wheat straw and cow manure waste for substrate preparation and reducing nutrient losses. In addition, the final mushroom residue can also be used as a leftover substrate for further utilization.

Heteroepitaxial Growth of NiO Thin Films on (‐201) β‐Ga2O3 by Mist Chemical Vapor Deposition

The growth of NiO epitaxial thin films on (‐201) β‐Ga2O3 by mist chemical vapor deposition (CVD) and the effects of carrier gas selection (N2 and O2) and substrate preannealing treatment on the structural and morphological properties on the grown thin films are explored. X‐ray diffraction analysis reveals successful epitaxial growth with the orientation relationship (111) NiO [0‐11] || (‐201) β‐Ga2O3 [010]. As a carrier gas, O2 results in single‐domain NiO films while N2 leads to the formation of rotational domains. Atomic force microscopy and field‐emission scanning electron microscopy confirm the lateral growth of NiO films, thus highlighting the importance of substrate preannealing at 1200 °C in oxygen atmosphere to obtain flat, high‐quality films. The results demonstrate that the method of mist CVD combined with appropriate substrate preparation and carrier gas selection is effective for the growth of high‐quality NiO/β‐Ga2O3 heterostructures. This achievement opens new possibilities for the development of wide‐bandgap p–n heterojunctions, potentially advancing the field of high‐power oxide‐based electronic devices.

Oxidation Behaviour of TiC/TiN Coatings Deposited by Chemical Vapor Deposition (CVD): Mechanisms, Structures, and Properties

This review explores the oxidation behavior of Titanium Carbide (TiC) and Titanium Nitride (TiN) coatings deposited by Chemical Vapor Deposition (CVD), with a focus on their industrial applications as wear-resistant coatings for cutting tools. It examines effect of process parameters—such as temperature, pressure, precursor composition, and substrate preparation—on formation and performance of TiC/TiN coatings. The review evaluates the microstructural characteristics of these coatings, including crystal structure, using X-ray diffraction analysis. Also, estimates the mechanical properties such as hardness, wear resistance, and adhesion strength. Additionally, the review covers the thermal stability of TiC/TiN coatings, emphasizing their ability to maintain structural integrity at high temperatures, which is essential for the performance of cutting tools and other industrial components. A major focus is the oxidation behavior of TiC/TiN coatings, including the impact of coating composition, deposition methods, and environmental conditions. The review details oxidation kinetics and mechanisms, revealing various stages of oxidation at different temperatures. It also examines oxide scale morphology and its effect on coating properties. Finally, this review reveals the importance of alloying elements, like silicon, in improving oxidation resistance. Composite coatings such as TiSiN and TiSiCN are shown to offer better high-temperature stability compared to traditional TiN coatings. The effects of coating thickness and the benefits of multilayer coatings for enhanced oxidation resistance are also discussed.

Introduction and Development of Surface-Enhanced Raman Scattering (SERS) Substrates: A Review.

Since its discovery, the phenomenon of Surface Enhanced Raman Scattering (SERS) has gradually become an important tool for analyzing the composition and structure of substances. As a trace technique that can efficiently and nondestructively detect single molecules, the application of SERS has expanded from environmental and materials science to biomedical fields. In the past decade or so, the explosive development of nanotechnology and nanomaterials has further boosted the research of SERS technology, as nanomaterial-based SERS substrates have shown good signal enhancement properties. So far, it is widely recognized that the morphology, size, composition, and stacking mode of nanomaterials have a very great influence on the strength of the substrate SERS effect. Herein, an overview of methods for the preparation of surface-enhanced Raman scattering (SERS) substrates is provided. Specifically, this review describes a variety of common SERS substrate preparation methods and explores the potential and promise of these methods for applications in chemical analysis and biomedical fields. By detailing the influence of different nanomaterials (e.g., metallic nanoparticles, nanowires, and nanostars) and their structural features on the SERS effect, this article aims to provide a comprehensive understanding of SERS substrate preparation techniques.

Unleashing the Potential of Different Method of Paddy Straw Substrate Bag for Enhanced Yield and Biological Efficiency of Milky Mushroom

Mushrooms, particularly Calocybe indica, are highly regarded for their distinctive flavour and numerous health benefits. This study investigates various method of paddy straw substrate bags: rolled paddy straw, intact paddy straw, and chopped paddy straw to optimize the cultivation of C. indica. Employing a Completely Randomized Design (CRD), we analysed growth parameters, yield, and biological efficiency of mushrooms cultivated on these substrates. The results indicated that chopped paddy straw was the most effective substrate, significantly reducing the time for spawn run to 14.20 days, pinhead formation to 11.80 days, and sporophore maturation to 10.20 days. This method yielded the highest overall production at 664.50 g, along with a biological efficiency of 66.45%. In contrast, intact paddy straw exhibited moderate growth performance, while rolled paddy straw resulted in the lowest yield at 451.30 g and took the longest time for all growth stages, which may be attributed to less compactness in the substrate beds. The number of sporophores produced also varied, with chopped paddy straw yielding an average of 10.6 sporophores, compared to 8.6 from intact paddy straw and 7.2 from rolled paddy straw. Although stipe length and pileus diameter showed non-significant differences among treatments, they did not contribute meaningfully to yield or biological efficiency. Overall, the findings highlight that chopped paddy straw is the most suitable substrate preparation method for cultivating C. indica, enhancing both yield and efficiency in production. This research contributes valuable insights for mushroom cultivation practices, particularly in tropical regions where high temperatures prevail.

A critical review of the microcosm method in soil animal ecology

The microcosm method is widely used in research on soil animal ecology because it allows for controlled manipulations of fauna, climate, and soil properties. However, differences in biotic and abiotic conditions between the microcosm and the natural soil ecosystem it is intended to represent may bias the experimental results. On the basis of literature, potential influences of the following factors were discussed: (1) Microcosm volume and duration of the incubation period. (2) Preparation of the microcosm substrate, with emphasis on the choice between homogenised substrate and intact soil cores. (3) Incubation conditions (moisture, temperature and drainage). (4) Biotic diversity in the microcosm soil, with emphasis on (a) the general problem of low biodiversity in microcosms, (b) the unnatural situation in microcosms without plants, (c) differences in microflora composition between “faunal” and “non-faunal” treatments, and (d) relative densities of the organisms present. Possible ways of dealing with a few of these problems were also discussed.

An Effective and Controllable Platform with Ag-Stepped Nanocone Arrays Serving as Stable SERS Substrate

Facile, controllable and efficient SERS substrate preparation has always been the focus project in the SERS field, especially the solid-state nanoarray substrate. Herein, a simple and convenient method for preparing a series of homogeneous Ag-stepped nanocone arrays (Ag-SNCAs) using polymer nanocompression printing is presented. By analyzing the 1162[Formula: see text]cm[Formula: see text] characteristic peak of crystal violet (CV), the relative standard deviation (RSD) of the Raman intensity was only 4.71%. The detection limit of malachite green (MG) reached 0.001[Formula: see text]ppm, and it also has good SERS detection results for drug molecules such as melamine, methadone, morphine, methamphetamine and thiabendazole. This work provides a large area uniform and controllable preparation method of sharp cone nanostructure array, which has important application in plasmonic photocatalysis and deep light field regulations.

A Comprehensive Review on Studying and Developing Guidelines to Standardize the Inspection of Properties and Production Methods for Mycelium-Bound Composites in Bio-Based Building Material Applications.

Mycelium-bound composites (MBCs) represent a promising advancement in bio-based building materials, offering sustainable alternatives for engineering and construction applications. This review provides a comprehensive overview of the current research landscape, production methodologies, and standardization ideas related to MBCs. A basic search on Scopus revealed over 250 publications on MBCs between 2020 and 2024, with more than 30% focusing on engineering and materials science. Key studies have investigated the physical and mechanical properties of MBCs, optimizing parameters such as substrate type, fungal species, incubation time, and post-processing to enhance material performance. Standardizing the inspection of MBC properties is crucial for ensuring quality and reliability. Various testing standards, including those from the American Society for Testing and Materials (ASTM), the International Organization for Standardization (ISO), the Japanese Industrial Standard (JIS), European Standards (EN), Deutsches Institut für Normung (DIN), and the Thai Industrial Standards Institute (TIS), are utilized to evaluate density, water absorption, compression strength, tensile strength, insulation, and other critical properties. This review highlights the distinction between lab-scale and apply-scale testing methodologies, emphasizing the need for comprehensive evaluation protocols. Additionally, the production process of MBCs involves critical steps like substrate preparation, fungal species selection, and mycelium growth, necessitating the implementation of good manufacturing practices (GMPs) to ensure consistency and quality. The internal and external structures of MBCs significantly influence their performance, necessitating standardized inspection methods using advanced techniques such as scanning electron microscopy (SEM), X-ray computed tomography (CT) scanning, and surface profilometry. By establishing robust inspection protocols and production standards, the industry can enhance the reliability and adoption of MBCs, contributing to innovations in materials science and promoting environmental sustainability. This review underscores the importance of interdisciplinary collaboration, advanced characterization tools, and regulatory frameworks to address challenges and advance the field of MBCs.

Assessment of concrete-to-concrete shear bond behavior using 3-D direct shear testing

The interfaces that develop when fresh concrete is poured onto existing substrates are noted for their vulnerability and influence on the durability and integrity of the composite structure. Studies on the shear bond properties and failure mechanisms of such composite concrete-to-concrete joints under normal stress are essential for developing predictive and numerical models that accommodate various levels of joint substrate roughness. This study aims to use an innovative 3D shearing box, BCR3D, to analyze the shear behavior of concrete-to-concrete joints under direct shear tests at a constant normal stress. The influence of the degree of surface roughness on the pure shear behavior of these joints was assessed at a normal stress level of 1 MPa. The substrate post-hardening surface morphology was evaluated using a high-resolution laser profilometer. Statistical surface roughness parameters were computed using MATLAB. A parametric study was carried out involving bond strength, residual shear stress, contractive-dilative behaviors, and total fracture energy. Results showed that bond strength, dilative normal displacement, and total fracture energy were proportional to the substrate surface roughness. Residual shear stress was not affected by the initial surface roughness. Dilative normal displacements were more significant for specimens with higher surface substrate roughness due to interlocking, with values reaching up to 1.77 mm. Joints with high substrate surface roughness exhibited similar bond strength and fracture energy to those obtained from the monolithic specimens, underscoring the significance of substrate preparation before casting new concrete layers.

Synthesis of TiO2 Thin Film with Cobalt Doping Using Sol-Gel Spin-Coating Technique as a Solar Cell Material

Research has been done on thin films by mixing TiO2 with cobalt doping and adding HCI as a solar cell material. The aim of this research is to produce a thin layer that is good for use in solar cells. This research has several stages, namely: 1) weighing cobalt and titanium; 2) glass substrate preparation; 3) making a sol-gel solution; 4) thin layer deposition; and 5) heating the sample. From these several stages, the result was that a pure TiO2 solution without doping obtained a thick white solution, whereas the more doping used, the fainter the color of the solution obtained. The thin-layer synthesis process uses a spin-coating method assisted by a modified centrifuge to evenly distribute the sol-gel solution on the surface of the glass substrate

Preparation and characterization of peptide-modified core-shell fibrous substrates with UV-blocking properties for corneal regeneration applications

Effective UV protection is a key aspect of substrates directly exposed to UV radiation. Therefore, in the present study, fibrous substrates of core–shell morphology (PCL-core, PVP-shell) containing peptides based on tryptophan, tyrosine and cysteine (W6, YYC2 and YYC3) were prepared. Spectrophotometric studies showed UV absorption by peptides containing tyrosine and tryptophan in the UVB (up to 80%) and UVA (up to 40%) ranges. Cysteine, in turn, contributed to high antioxidant properties, confirmed by DPPH assay. The presence of peptides contributed to a nonwoven fabric characterized by the ability to absorb UV radiation and prevent the occurrence of oxidative stress (caused by the presence of free radicals). In turn, the increase in the surface zeta potential of the nonwoven after UV irradiation and higher thermal stability (demonstrated by DSC studies) indicated the crosslinking of the PVP layer under UVR, which further contributes to the increased protection of the nonwoven against its effects. In summary, obtained nonwoven exhibited functional similarity to the native cornea, providing a potential solution for enhancing corneal tissue engineering and regenerative medicine applications.

Highly sensitive SERS detection of melamine based on 3D Ag@porous silicon photonic crystal

The stability, reproducibility and engineering of SERS substrate faces a great challenge in melamine SERS assay. In this work, a simple, highly sensitive, stable and cost-efficient SERS detection platform for melamine was established based on its Raman fingerprints spectrum. The Ag@ porous silicon photonic crystal (Ag@PPC) was prepared as the 3D SERS substrate by electrochemical etching and magnetron sputter technology. The main influence factors for the preparation of SERS substrate were investigated in detail. The analytical enhancement factor of the 3D SERS substrate can reach to 2.6 × 108. The 3D SERS detection platform showed a wide linear detection range of 10−4∼10 mg L−1 and a low limit of detection of 0.1 μg L−1 for melamine. Moreover, such detection platform showed good stability, high reproducibility and high recovery rates for melamine. The 3D Ag@PPC SERS substrate can be easily prepared and engineered, displaying a great potential application in food safety field.

Preparation of flexible SERS substrate with excellent performance based on the electrospraying technique

Paper-based flexible surface-enhanced Raman scattering (SERS) substrate has significant advantages in the detection of pesticide residues on the surface of fruits and vegetables due to its full contact with the sample surface. However, it is found that the development of new paper-based flexible SERS substrate preparation technology is still necessary through the evaluation of the current preparation technology. In addition, the development of new application scenarios can also promote the further development of SERS technology. Herein, a highly sensitive paper-based flexible SERS substrate is prepared by depositing Cu2O/Ag(4) composite particles on commercial filter paper by electrospraying technique. Compared with other preparation technologies, in addition to the characteristics of simplicity and speed, more importantly, it will not cause waste of nanoparticles. By adjusting the parameters, the optimized substrate shows excellent SERS performance with the minimum detection concentrations are 10−9 M and 10−9 M for R6G and thiram, respectively. It also has good linear correlation of concentration (R2 = 0.952), good reproducibility, and excellent time stability. Furthermore, based on the good filtration characteristics of commercial filter paper, the rapid detection of pesticide residues in soil was successfully realized. This proposed a new scheme for the practical application of SERS technology in the field of food and environmental safety.

Direct Writing of SERS Substrates Using Femtosecond Laser Pulses.

Achieving a high-density, repeatable, and uniform distribution of "hotspots" across the entire surface-enhanced Raman scattering (SERS) substrate is a current challenge in facilitating the efficient preparation of large-area SERS substrates. In this study, we aim to produce homogeneous surface-enhanced Raman scattering (SERS) substrates based on the strong interaction between femtosecond laser pulses and a thin film of colloidal gold nanoparticles (AuNPs). The SERS substrate we obtained consists of irregularly shaped and sharp-edged gold nanoparticle aggregates with specially extruding features; meanwhile, a large number of three-dimensional AuNP stacks are produced. The advantages of such configurations lie in the production of a high density of hotspots, which can significantly improve the SERS performance. When the laser fluence is 5.6 mJ/cm2, the substrate exhibits the best SERS enhancement effect, and a strong SERS signal can still be observed when testing the concentration of R6G at 10-8 mol/L. The enhancement factor of such SERS substrates prepared using femtosecond laser direct writing is increased by 3 orders of magnitude compared to the conventional furnace annealing process. Furthermore, the relative standard deviation for the intensities of the SERS signals was measured to be 5.1% over an area of 50 × 50 μm2, indicating a highly homogeneous SERS performance and excellent potential for practical applications.

Waste as a Sustainable Source of Nutrients for Plants and Humans: A Strategy to Reduce Hidden Hunger

Worldwide, over half of all preschool-aged children and two-thirds of non-pregnant women of reproductive age suffer from hidden hunger. This situation may worsen due to the expected increase in the world population and the effects of climate change. The objective of this paper is to conduct a review of the relationship between soil, plants, and humans at the nutritional level, factors that affect the availability of nutrients, and sustainable strategies to reduce hidden hunger from an organic waste utilization point of view. Nutritional deficiency in people begins with nutrient-deficient soil, followed by crops that do not meet humans’ nutritional needs. According to previous studies, most agricultural soils are deficient in nutrients; however, organic residues containing high concentrations of minerals are present in the non-edible parts that are discarded. New opportunities (based on the circular economy strategy) are opening up to take advantage of the nutrient pool of organic residues, such as the preparation of substrates (technosols) or amendments. Their incorporation into the soil may consider various circumstances to ensure the mineralization and bioavailability of nutrients for crops. Several agronomic practices and methods to monitor soil and crop nutrient depletion can be considered among the best strategies to mitigate and reduce hidden hunger through determining which foods and which parts should be ingested, and how to process them to ensure mineral bioavailability.

3‑Amino Oxindole Schiff Base Efficiently Paired with p‑Quinone Methide to Enable a New Diastereoselective and Enantioselective 1,6-Conjugated Addition in the Presence of a Cinchonidinium Phase Transfer Catalyst

3‑Amino oxindole Schiff base has been used as an efficient substrate company with p‑quinone methides for a new highly diastereoselective and enantioselective 1,6-conjugate addition in the presence of a O-allyl-N-(9-anthracenylmethyl) cinchonidinium bromide phase transfer catalyst under mild reaction conditions. A broad series of chiral quaternary 3-amino oxindoles with 4-hydroxybenzyl scaffold were smoothly obtained in good to excellent yields with excellent diastereoselectivities (>20:1) and enantioselectivities (up to 99 % ee). A typical scale-up preparation and subsequent hydrolysis of a pyridine substrate was successfully performed and a potential valuable chiral amino-pyridine bifunctional chiral building block was obtained, which is structurally feasible as chiral ligand for asymmetric metallic catalysis.

Reusable Ag SERS substrates fabricated by tip-based mechanical lithography

Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive, non-destructive technique that amplifies molecular scattering signals via engineered 'hot spots' at the micro/nanoscale. However, currently SERS substrates still face problems such as disposable use, poor consistency, strict environmental requirements, and complex processing processes. The development of new SERS substrates is crucial for advanced detection. In this study, a reusable and consistent Ag-based SERS substrate was developed with scanning probe lithography (SPL). Based on the designed machining with a diamond tip, the effects of parameters, including normal load, scanning feed/spacing, period and amplitude, on the formation of micro/nanostructures on Ag surface were investigated to meet the best candidate for SERS substrate. This method can be applied to soft metals like Au, Ag, and Cu, with Ag substrates demonstrating a higher Raman detection limit compared to Au or Cu. Finally, the reuse of Ag SERS substrate was achieved by surface cleaning and/or oxide layer removing. This study highlights a low-cost and feasible approach to high-performance SERS substrate preparation, with significant potential for practical applications and further research.