Substrate Preparation Research Articles

Fabrication technology of void embedded silicon-on-insulator substrate

Void embedded silicon-on-insulator (VESOI) substrate is a newly developed silicon-on-insulator (SOI) substrate for advanced complementary metal oxide semiconductor (CMOS) devices and integration technology. However, in the ion-cutting process for preparing the substrate, numerous hydrogen bubbles aggregate at the cut interface, which compresses the cavity structure and might cause the thin film above the cavity to be damaged and delaminated. Therefore, it is necessary to conduct in-depth research on the stress mechanism and process stability in the preparation of VESOI substrates. This study focuses on a single rectangular cavity structure and uses the fixed-supported beam theory to analyze its mechanical behavior during fabrication, and a three-dimensional model of cavity structure is constructed by using the finite element analysis tool. Through stress simulation, the failure mechanism of the cavity structure is identified, and the weak points are confirmed. The results show that the short side length (<i>w</i>), top silicon film thickness (<i>t</i>), and hydrogen bubble pressure are the main factors affecting the stress state of the top silicon film. When the <i>w</i>/<i>t</i> ratio exceeds 4–5, the silicon film will fracture owing to excessive tensile stress, and the fracture site is along the long side of the rectangular cavity. By increasing the thickness of the top silicon film slightly and adding support structures inside the cavity (to reduce <i>w</i>), this work successfully prepares high-quality 8-inch VESOI substrates that meet the requirements for the CMOS production line. The present study is expected to provide valuable idea for the development of integrated technologies relying on VESOI substrates.

USE OF ANIMAL PRODUCT PROCESSING WASTE IN OYSTER MUSHROOM PRODUCTION TECHNOLOGY

The article presents a study of the possibility of using animal husbandry processing waste as a nutrient additive to compositions of synthetic fermented substrate for the cultivation of oyster mushrooms. Wastes that are of low value for use in other branches of agriculture and industry and are mainly disposed of as solid waste by burial were investigated. In modern economic conditions, it is important to reduce the cost of the substrate, one of the possible ways to achieve this goal is the use of cheaper raw materials. Meals and bran are traditionally used to balance the substrate in terms of nitrogen content. These products are waste products from the processing of agricultural crops and are also classically used to balance the rations of farm animals and poultry. This creates competition between industries and increases the price of raw materials, which ultimately causes an increase in product prices. Therefore, the search and research of alternative balancing components for the preparation of oyster mushroom substrate, which are not competitive for animal husbandry, is relevant. The analysis of the obtained results made it possible to form the following conclusions: their use as additives for the preparation of the substrate will allow them to be used in further processing, with the obtaining of additional products of mushroom production, the study of the growth of colonies of oyster mushrooms using the selected additives made it possible to determine the best options: yes, the addition of skin shavings and the addition of pores It does not inhibit the colonization of these additives, but, on the contrary, increases the growth rate of colonies compared to colonies developed without additional nutrition; the obtained data of the laboratory experiment can be considered primary and those that require further research, including when using other methods of preparation of additives (sterilization, solid-state fermentation), as well as verification in scientific and economic experiments on the determination of technological properties in substrate compositions and the calculation of biological effectiveness and productivity of oyster mushrooms and other saprophytes.

Transformation of plant residues into a humus-like substance using biological means of multifunctional action

Purpose. Justification of the technology of biological transformation of plant remains into a humus-like substance thanks to the microbial agents of the drug Extrakon, ensuring the improvement of the soil and the initiation of its biological cycles. Methods. Complex of modern and generally accepted physicochemical, microbiological, physiolo- gical and biochemical research methods; methods of laboratory and field research; statistical analysis of the data. Results. A promising, innovative scientific- methodological development and technology for the use of the multifunctional biological preparation Extrakon has been created, which is guaranteed to improve the soil, nourish plants and accelerate the processes of transformation of organic matter (plant residues) into a humus-like substance. Scientifically substantiated expediency of using the drug Extrakon in the processes of accelerated composting of crop production waste (according to indicators of biothermal processes, kinetics of temperature regimes and decomposition of organic matter of siderate, as well as changes in the physical and chemical properties of compost depending on the duration of its preparation). The transformation of straw and plant residues with the help of a consortium of natural soil microorganisms takes from 30 days to 6–8 months. Conclusions 1. Loose and liquid preparations based on a consortium of soil microorganisms (CSM) are effective for preparing and improving substrates and soil, pre-sowing seed treatment, feeding plants during the growing season; post-harvest use – to activate the transformation of plant residues, composting organic cellulose-containing residues. 2. The duration of the plant residues transformation is from 30 days to 6–8 months, which is 2-3 times less than when using existing biodestroyers. The effect of biological preparation in the agricultural cluster is from 80 % to complete transformation of organic substances into a humus- like substance. 3. The proposed preparation can be used both for the transformation of plant residues into a humus- like substance, composting, and for the preparation and improvement of various substrates, soil, as well as for the purpose of eliminating toxicity, for growing plants in closed and open soils. Keywords: humus-like substance, consortium of soil microorganisms, plant remains, transformation

Эколого-экономические аспекты культивирования лекарственных грибов ежовика гребенчатого (Hericium erinaceus)

The results of studies on the effect of the substrate composition for the cultivation of Lion’s mane mushroom (Hericium erinaceus) are presented. The search for alternative raw materials for the preparation of substrates is associated with the possibility of using lignin-ammonium compost, balanced in terms of basic nutrients, which is much cheaper than oak sawdust and is more accessible in the region. Replacing brown rice by wheat grain in the substrate contributed to the enrichment of the mass with vitamins, proteins and essential amino acids. The possibility of using a lignin component in the substrate composition in the form of ligninammonia compost (50%) and wheat grain (20%), partially replacing expensive and scarce raw materials (oak sawdust, brown rice), was evaluated. The use of a new substrate composition promotes the active colonization of the substrate mass by the mycelium of medicinal Lion’s mane mushroom of the Beard and Belgium strains (97–99%), additional (by 0.39% of the substrate mass) collection of fruiting bodies of the Beard strain and increased (by 1.6%) yield of dry mass of products of the Beard and Belgium strains. The economic effect of growing H. erinaceus on the developed substrate is expressed in profit (for the Beard strain – 20,540 rubles, for the Belgium strain – 5,860 rubles), while on the classical substrate a loss is obtained. The profitability of the mushroom production of the studied strains on the experimental substrate is 16.4% for the Beard strain and 4.68% for the Belgium strain, on the classical substrate – 12.1% and 21.0%, respectively. Reducing the cost of mushroom products may have a positive effect on the purchasing power of consumers. The addition of a lignin component to the substrate promotes the utilization of of hydrolytic lignins in large quantities, thus improving the environmental situation in the places where they are stored.

Research on a three-dimensional SERS substrate based on a CNTs/Ag@Au/SiO2 composite for detection of fipronil and imidacloprid pesticides.

Surface-enhanced Raman scattering (SERS) has a unique fingerprint spectrum, which allows for rapid, highly sensitive, and non-destructive detection without the need for sample pretreatment. However, SERS substrates have disadvantages such as short storage time and poor reproducibility. In this study, carbon nanotubes, gold, and silver were combined to take advantage of their inherent structural and characteristic properties that enhance the Raman effect. A new type of SERS composite substrate, CNTs/Ag@Au/SiO2, was prepared using a hydrothermal method and seed growth method. The substrate was characterized using transmission electron microscopy (TEM), and the average distance between the core-shell nanoparticles was found to be 3.1 nm, which is more suitable than other gold-silver combined core-shell structures and significantly improves the SERS enhancement factor. The substrate demonstrated high sensitivity even at low concentrations of probe molecules and good uniformity at five randomly selected locations. After storage for 45 days, the substrate still exhibited good stability. In most gold-silver combined core-shell structures, the detection limit for Rhodamine 6G (R6G) is 10-9 mol L-1, while in this substrate, the detection limit for R6G is 10-11 mol L-1. Furthermore, the contribution of the substrate's enhancement was deeply investigated using finite-difference time-domain (FDTD), which revealed that the substrate's hotspots were present in two forms: the "hotspots generated between Ag@Au nanoparticles" and the "hotspots generated between Ag@Au nanoparticles and carbon nanotubes". These two forms of hotspots also demonstrated that the performance brought about by the preparation of the substrate structure was reliable. The simulation results were compared with the experimental results, and the analysis showed that the real environment would have an impact on the substrate's structure during the actual substrate preparation process. Finally, the substrate was used for detecting the pesticide fipronil, and the results showed clear peaks even at a concentration of 0.1 mg L-1. The results indicated that the Raman intensity was linearly exponential with the fipronil solution concentration, with a determination coefficient of R2 = 0.991. This study provides a new SERS substrate for pesticide residue detection and further explores the improvement of pesticide detection limits.

Preparation of SERS substrate with 2D silver plate and nano silver sol for plasticizer detection in edible oil

As a widely used industrial additive of plastic products, phthalate ester (PAE) plasticizers can easily migrate into food, threatening human health. In this work, we proposed a rapid, precise, and reliable method to detect PAE plasticizers in edible oils by using surface-enhanced Raman spectroscopy (SERS) technology. A two-dimensional (2D) silver plate synergizing with a nanosilver sol was prepared as a substrate for SERS to detect potassium hydrogen phthalate (PHP), a hydrolysate of a PAE plasticizer. Detection conditions, such as pH values, drying times, and hydrolysate interference, were optimized. The working curve was well fitted with a linear parameter R2 of 0.9994, and the minimum detection limit was evaluated as 10−9 mol/L. Furthermore, the detection accuracy was supported by five edible oil samples. Therefore, using SERS technology to detect PHP is expected to provide an avenue for PAE plasticizer detection in oils and fats, and it features promising potential applications in food safety.

Optimized Design and Preparation of Ag Nanoparticle Multilayer SERS Substrates with Excellent Sensing Performance.

Nanoparticle multilayer substrates usually exhibit excellent SERS activity due to multi-dimensional plasmon coupling. However, simply increasing the layers will lead to several problems, such as complex manufacturing procedures, reduced uniformity and poor reproducibility. In this paper, the local electric field (LEF) characteristics of a Ag nanoparticle (AgNP) multilayer were systematically studied through finite element simulations. We found that, on the glass support, the LEF intensity improved with the increase in the layers of AgNPs. However, the maximum LEF could be obtained with only two layers of AgNPs on the Au film support, and it was much stronger than the optimal value of the former. To verify the simulation results, we have successfully prepared one to four layers of AgNPs on both supports with a liquid-liquid interface self-assembly method, and carried out a series of SERS measurements. The experimental results were in good agreement with the simulations. Finally, the optimized SERS substrate, the 2-AgNP@Au film, showed an ultra-high SERS sensitivity, along with an excellent signal uniformity, which had a detection ability of 1 × 10-15 M for the Rhodamine 6G (R6G) and a relative standard deviation (RSD) of 11% for the signal intensity. Our study provides important theoretical guidance and a technical basis for the optimized design and application of high-performance SERS substrates.

A Review of Magnetic Nanoparticle-Based Surface-Enhanced Raman Scattering Substrates for Bioanalysis: Morphology, Function and Detection Application.

Surface-enhanced Raman scattering (SERS) is a kind of popular non-destructive and water-free interference analytical technology with fast response, excellent sensitivity and specificity to trace biotargets in biological samples. Recently, many researches have focused on the preparation of various magnetic nanoparticle-based SERS substrates for developing efficient bioanalytical methods, which greatly improved the selectivity and accuracy of the proposed SERS bioassays. There has been a rapid increase in the number of reports about magnetic SERS substrates in the past decade, and the number of related papers and citations have exceeded 500 and 2000, respectively. Moreover, most of the papers published since 2009 have been dedicated to analytical applications. In the paper, the recent advances in magnetic nanoparticle-based SERS substrates for bioanalysis were reviewed in detail based on their various morphologies, such as magnetic core-shell nanoparticles, magnetic core-satellite nanoparticles and non-spherical magnetic nanoparticles and their different functions, such as separation and enrichment, recognition and SERS tags. Moreover, the typical application progress on magnetic nanoparticle-based SERS substrates for bioanalysis of amino acids and protein, DNA and RNA sequences, cancer cells and related tumor biomarkers, etc., was summarized and introduced. Finally, the future trends and prospective for SERS bioanalysis by magnetic nanoparticle-based substrates were proposed based on the systematical study of typical and latest references. It is expected that this review would provide useful information and clues for the researchers with interest in SERS bioanalysis.

An Industrial Perspective on Challenges in the Lifetime Prediction of Organic Coatings: A Century Retrospective Review

There has been a dedicated effort by multiple groups to determine which performance attributes of coatings, such as adhesion, electrochemical properties, and appearance will give an indication of the overall performance of a coating. Complicating lifetime performance predictions of coatings are the many variables that consistently change in differing industrial markets—substrates, pretreatments, coating chemistries, and coating layers to name a few, with coatings failing in different manners. While the focus of this paper is the lifetime prediction of corrosion performance in atmospheric corrosion scenarios, it should be noted that there are other failure modes (Table 1), beyond corrosion, which may be considered “end of life” by users. These include appearance changes such as ultraviolet (UV) degradation resulting in color, gloss loss, coating erosion and loss, or changes in adhesion strength. While these failure modes are out of scope for this paper, it must be realized that the chemical changes occurring during UV exposure may significantly impact the coating performance in the area of corrosion. To be of value, lifetime prediction must accurately determine the coating lifetime when under real-world conditions, noting that accelerated testing protocols used in lifetime prediction studies need to be interpreted with caution, as many do not accurately replicate the modes of failure that occur during real-world use. Complicating this is the fact that coatings are studied in the laboratory under ideal conditions, with well-prepared substrates, and properly applied and cured coatings at controlled dry coating thicknesses. Coating lifetimes in the field are often not determined by this “Best Case Scenario.” Instead, coatings tend to fail in use due to substrate preparation issues, application defects, incomplete cure, damage during use, along with a variety of other unknown unknowns.

Perspectives on MOVPE-grown (100) β-Ga2O3 thin films and its Al-alloy for power electronics application

Beta gallium oxide (β-Ga2O3) is a promising ultra-wide bandgap semiconductor with attractive physical properties for next-generation high-power devices, radio frequency electronics, and solar-blind ultraviolet radiation detectors. Here, we present an overview and perspective on the development of MOVPE-grown (100) β-Ga2O3 thin films and its role in supplementing high-power electronics. We review the development path of the growth process on (100) β-Ga2O3 thin films with a discussion regarding the solved and remaining challenges. The structural defect formation mechanism, substrate treatment strategies, and different growth windows are analyzed to optimize the grown film to fulfill the requirements for device fabrication. Toward industrial applications, MOVPE-grown β-Ga2O3 thin films are evaluated in two aspects: thick layers with smooth surface roughness and the electrical properties in terms of high carrier mobility and low doping concentration. Based on the reviewed results, we propose strategies in substrate preparation treatments and supportive tools such as the machine learning approaches for future growth process optimization and envision the rising interest of the β-Ga2O3-related alloy, β-(AlxGa1−x)2O3.

Fate of antibiotic resistance genes in cultivation substrate and its association with bacterial communities throughout commercial production of Agaricus bisporus

Animal manure is an important raw material for Agaricus bisporus production; however, it is also a reservoir for antibiotic residues, antibiotic resistance genes (ARGs), and antibiotic-resistant bacteria. Little is known about the influence of the commercial cultivation of A. bisporus on the dynamics of ARGs and the underlying mechanisms that cause their variations. In this study, we investigated the fate of 285 ARGs, 10 mobile genetic elements, and seven major categories of antibiotic residues in substrate and mushroom samples at different production phases. The results showed that commercial substrate preparation, particularly the pasteurization phase, was highly efficient in removing ARGs from the substrate. We further found that mycelium proliferation of A. bisporus contributed significantly to the removal of ARGs from the substrate and casing soil. The bacterial community is the key driver of changes in ARGs during the commercial cultivation of A. bisporus, which explained 46.67% of the variation in ARGs. Our results indicate that, despite the addition of animal manure, the risk of ARG dissemination to fruiting bodies and the environment is low. We propose that bioremediation by specific edible fungi might be a novel and promising method for scavenging antimicrobial resistance contamination from soil environment.

Nanofibrous aerosol sample filter substrates: Design, fabrication, and characterization

The manuscript demonstrates the application of nanofibrous filtration technology to aerosol sampling, by suggesting the fabrication sequence and laboratory validation of sampling filters. Four multilayer composite filters were developed from polymers Polyc[ε]aprolactone (PCL), Cellulose acetate (CA), Poly(1-acrylonitrile) (PAN), and Poly(hexano-6-lactam) (PA6) by two modifications of electrospinning process. The layered structure provided a fibre and pore gradient from the microfibrous base layer, the mesofibrous middle layer, and the nanofibrous upper layer, acting as a 2D collection surface for aerosol particles. The sampling filters were characterized for their morphology, wettability, weight stability, filtration efficiency, and pressure drop. The fibre diameter of the nanofibrous layer ranged from 0.42 ± 0.21 μm (PCL) to 0.086 ± 0.02 μm (PA6), while pore size ranged from 2.83 ± 0.35 μm (CA) to <0.4 μm (PA6). Such a morphology allowed for reaching a consistent particle collection efficiency ranging between 99.4 and 99.9% at a particle size of 0.3 μm, and at a reasonable pressure drop, such as 0.5–2.2 kPa at a face velocity of 10 cm/s. The fabrication sequence and obtained indicate a suitability for the preparation of bespoke filtering substrates to suit a specific subsequent physical, chemical, or toxicological analysis of collected particles.

Electrically controllable self-assembly of gold nanorods into a plasmonic nanostructure for highly efficiency SERS.

In this Letter, a method for the rapid and efficient preparation of ultrasensitive detection substrates by assembling gold nanorod suspensions with the application of an alternating current (AC) field is proposed, and it is found that frequency and voltage are the effective means of regulation. A sandwich structure (parallel SiO2 plate) not only effectively slows down the evaporation rate, but also visually reveals the changes in the assembly process. Under the optimal assembly conditions, the sensitivity and uniformity of the substrate to different probe molecules are tested. The Raman detection results experimentally show that the detection limits of Rhodamine 6G (Rh6G), crystal violet (CV), and Aspartame (APM) molecular solutions are 10-14 M, 10-10 M, and 62.5 mg/L, respectively, and the mixed dye molecular solutions can also be effectively distinguished. Furthermore, Rh6G and CV characteristic peaks at 1647 cm-1 and 1619 cm-1 were measured at randomly selected positions, and their relative standard deviations (RSDs) were 5.63% and 8.45%, respectively, indicating that the substrate has good uniformity. The effective regulation of the self-assembly results of nanoparticles will further enhance the practical application effect of surface-enhanced Raman technology and expand the application prospects of this technology.

Cryogenic ultrasonic vibration assisted turning to texturize AZ31 magnesium alloy surfaces

Magnesium alloys are increasingly used in the biomedical field thanks to their biocompatibility. However, poor corrosion resistance greatly limits their applications. Coating the devices is known to represent the most efficient way to increase the corrosion performances of magnesium alloys, but it requires specific surface preparation of the metal substrate. In the present paper, a hybrid machining technology, namely cryogenic–ultrasonic-assisted turning, is applied to generate magnesium alloy texturized surfaces with enhanced surface integrity characteristics. Results showed that the application of liquid nitrogen led to a harder and more complex surface texture than in the case of ultrasonic-assisted turning under dry conditions.

Label-free detection of Thiram pesticide on flexible SERS-active substrate

Thiram (tetramethyl thiuram disulfide) is a fungicide and is used for crop protection. It has several health-related issues when we consume this for a long period. Food and drug administration (FDA) warns higher than 30 μM (7 ppm) limit. Hence, the monitoring of the Thiram pesticide in foods and vegetables is of utmost importance. Conventional techniques such as GC–MS, HPLC and LC-MS available for quantification of pesticides are very costly, time-consuming and require sophisticated laboratory with highly skilled manpower. This work aims to design and develop an efficient label-free SERS (Surface Enhanced Raman Spectroscopy) active substrate which can detect a very low-level concentration of pesticides with low cost and simple process. SERS is a surface-sensitive technique that provides the enhanced form of Raman signals. Gold nanoparticles are used for SERS-active substrate preparation which has been synthesized by the chemical reduction method. Thiram pesticide with concentration as low as 1 nM is detected with the SERS substrate developed in this work. This makes rapid and on-site detection of pesticides feasible in future.

Preparation of Poly(β-malic acid) via Direct Carbonylative Polymerization of Benzyl Glycidate.

Poly(malic acid) (PMLA) is a water-soluble, biodegradable, biocompatible, and nontoxic polyester in the poly(hydroxyalkanoate) (PHA) family. it features various applications in pharmaceutical field. Herein, NaCo(CO)4 and pyridine derivatives are employed for direct carbonylative polymerization of benzyl glycidate (BG) for poly(β-malic acid) production. Further investigation on reaction mechanism reveals that this polymerization undergoes a direct chain growth, rather than a sequential process involving β-lactone intermediate. The low cost and facile preparation of epoxide substrate render this methodology extremely appealing that avoids the rather tedious procedures for β-malolactonate synthesis required toward ring opening polymerization. This study also represents an alternative strategy over traditional methods for poly(β-malic acid) production using step growth polycondensation of malic acid.

Relationships between soil properties and species establishment in the restoration of mined soils in the Cerrado biome.

Restoring the ecosystems of the Cerrado biome is challenging considering the diversity of phytophysiognomies present in the biome, some of which are composed of species from different strata (herbaceous, shrubby, and arboreal), which increases the complexity of restructuring the floristic composition. Other factors was involved, such as soil quality, which directly influences the success of restoration, water storage, and nutrients, the financial costs, and a slow ecological process, due to the adverse circumstances found in the area. be restored. The strong anthropogenic interventions by mining processes reduce dramatically the physical and nutritional composition of the soil. We studied two restoration areas in Paracatu, Brazil, to examine their edaphic conditions six years after mining activities ceased and relate them to the status of the restoration process. In 2009, a Cerrado restoration were established in an area previously explored for gravel extraction. Plants were sampled and identified in 11 transects along the planting lines. The diameter base (DB) and total height (HT) were measured. The physical/chemical quality of the soil substrate was determined using a collection of samples in open trenches at four types of points: Cerrado (TC); dead plant pits (TM); seedling pits having living individuals of the most abundant species (TT); and those of the second-most abundant species (TE). Cecropia pachystachya Trécul and Tapirira guianensis Aubl. were most abundant and demonstrated the potential to thrive in areas degraded by mining having low mortality rates and growth at relatively DB and HT. The physical quality indicators in the gravel pits were not limiting, indicating that substrate preparation was efficient in this regard. The organic matter content in TM, TT, and TE was low in comparison to that of TC, and the chemical conditions in the TE pit substrates were similar to those in TM pits, suggesting C. pachystachya is a species with good plasticity, whereas T. guianensis is present in pits with higher levels of phosphorus.

Molecular beam epitaxial growth of multilayer 2D-boron nitride on Ni substrates from borazine and plasma-activated nitrogen

2D boron nitride (2D-BN) was synthesized by gas-source molecular beam epitaxy on polycrystalline and monocrystalline Ni substrates using gaseous borazine and active nitrogen generated by a remote plasma source. The excess of nitrogen atoms allows to overcome the thickness self-limitation active on Ni when using borazine alone. The nucleation density and the shape of the 2D-BN domains are clearly related to the Ni substrate preparation and to the growth parameters. Based on spatially-resolved photoemission spectroscopy and on the detection of the π plasmon peak, we discuss the origin of the N1s and B1s components and their relationship with an electronic coupling at the interface. After optimization of the growth parameters, a full 2D-BN coverage is obtained, although the material thickness is not evenly distributed. The 2D-BN presents a granular structure on (111) oriented Ni grains, showing a rather poor cristallographic quality. On the contrary, high quality 2D-BN is found on (101) and (001) Ni grains, where triangular islands are observed whose lateral size is limited to ∼20 μm.

Production of oyster mushroom (Pleurotus ostreatus) on sawdust supplemented with anaerobic digestate

Anaerobic digestion of organic waste results in production of biogas and a nutrient-rich digestate that has an established use as fertilizer in plant production. This study evaluated use of anaerobic digestate based on a high concentration of organic household waste as a fertilizer in sawdust-based production of oyster mushrooms (Pleurotus ostreatus). Inclusion of 0.5 L of anaerobic digestate (AD) per kg sawdust gave similar productivity in terms of biological efficiency (79.5 ± 5.4 %), and protein concentration (24.7 ± 2.4 % of dry weight (dw)) as standard mushroom substrate (78.1 ± 5.3 %, and 21.9 ± 3.0 % of dw, respectively). However, mushroom growth was impaired at the highest concentration of anaerobic digestate tested, 1 L digestate per kg dw sawdust. Comparison of the AD-fertilized substrate with a mushroom substrate with standard components (sawdust, wheat bran, calcium sulfate) and with similar C/N-ratio revealed some differences in elemental composition of the fruiting bodies, with an major increase in sodium concentration for the AD-fertilized substrate compared with the standard substrate (413.3 ± 28.9 and 226.7 ± 30.6 mg kg−1 dw, respectively). This difference can be explained by high sodium concentration in the anaerobic digestate, most likely due to inclusion of food scraps from households and restaurants in the biodigester feedstock. Screening of both substrates for a total of 133 micropollutants revealed that total sum of micropollutants was significantly higher in the AD-fertilized substrate (258 ± 12 ng/g dw substrate) than in the standard substrate (191 ± 35 ng/g dw substrate). Nitrogen losses during preparation of the AD-fertilized substrate were negligible.

Influence of Base Material and Addition of Complexing Agent to Deposition Bath for Galvanic Preparation of SERS-active Layers and Spectra of Riboflavin

SERS spectroscopy remains not a well-established analytical technique mainly because of the complicated preparation of SERS-active substrates, which often have low reproducibility. For this reason, the development of new or optimization of existing substrates is important. For testing the SERS activity of these substrates, the so-called model analytes are commonly used. One of them is riboflavin, which is utilized for its non-toxicity and suitable optical properties.&#x0D; This work is focused on optimizing the enhancing properties of galvanically prepared silver substrates. The influence of the base material (Al and its alloys, Zn) and of the addition of a complexing agent (EDTA) into the Ag deposition bath on the spectral response of riboflavin was evaluated. Each prepared substrate was characterized by scanning electron microscopy, and the SERS spectra were collected using an excitation wavelength of 1064 nm. All data were subsequently processed and interpreted using multivariate statistics, namely principal component analysis. The most universal and suitable base material for the preparation of Ag substrate for riboflavin detection was the AlMg alloy. The addition of a complexing agent to the deposition bath changed the morphology of the prepared substrates and the highest spectral response of riboflavin was obtained by adding 0.55 mM EDTA. The intensity of riboflavin spectral response was comparable to the value obtained using substrates prepared in the Ag bath, but the substrates prepared in the AgNO3 solution achieved a weaker enhancement of the spectral response.