Substrate Pretreatment Research Articles

High-Performance Anodes Made of Metallic Lithium Layers and Lithiated Silicon Layers Prepared by Vacuum Technologies

Replacing conventional electrode materials is one of the most pressing challenges for next-generation lithium-ion batteries since state-of-the-art systems have almost reached their limitations for performance gains. For anodes, ambitious candidates include lithium and silicon because of their extremely high capacity. In this paper, a physical vapor deposition process for the preparation of pure metallic lithium layers and lithiated silicon layers in the layer thickness range of 1–20 µm is demonstrated. The lithium layers were deposited by thermal evaporation. Static coating rates up to 120 nm/s and dynamic deposition rates up to 1 µm·m/min were realized. Furthermore, the deposition of lithiated silicon alloy layers with various compositions was performed via the co-evaporation of lithium and silicon, where silicon was evaporated by an electron beam. The process was characterized regarding the deposition rate, heat loads, and effects of substrate pre-treatment. To achieve a porous microstructure, the layer morphology needed to be manipulated by adapting process parameters. Stripping experiments revealed high electrochemical activity of the lithium up to 85 %. The innovative approach carried out via vacuum processing showed capabilities for overcoming the current bottlenecks experienced with high-capacity anode materials in combination with the potential for upscaling to high throughput production.

Evaluation of Bronze Electrode in Electrical Discharge Coating Process for Copper Coating.

One of the widely used non-traditional machines for machining of hard materials into complex shapes and different sizes is the electrical discharge machine (EDM). Recently, the EDM has been used for deposition by controlling the input parameters (current and duty cycle). This work was carried out to evaluate the readily available bronze (88% Cu + 12% Sn) electrode for deposition of copper material on titanium alloy. Experiments were conducted according to Taguchi experimental design considering the input parameters of current, Ton, Toff and preheating temperature of substrates. Titanium alloy was further hardened by preheating at temperatures of 100 °C, 300 °C and 500 °C and quenching in brine, castor oil and vegetable oil in order to avoid workpiece erosion. After this treatment, hardness, grain area, grain diameter and number of grains were characterized to compare with pretreated substrates. Then, the treated substrates were taken for copper deposition with the EDM. Output parameters such as material deposition rate (MDR), electrode wear rate (EWR), coating thickness (CT), elemental composition and surface crack density (SCD) were found. Material characterization was carried out using a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) and optical microscopy. Output parameters were optimized with technique for order of preference by similarity to ideal solution (TOPSIS) to find optimum parameters. A sixth experiment with parameter values of Ton of 440 µs, Toff of 200 µs, preheating temperature of 300 °C and quenching medium of castor oil was optimum with MDR of 0.00506 g/m, EWR of 0.00462 g/m, CT of 40.2 µm and SCD 19.4 × 107 µm2.

The xylobiohydrolase activity of a GH30 xylanase on natively acetylated xylan may hold the key for the degradation of recalcitrant xylan

Acetyl substitutions are common on the hemicellulosic structures of lignocellulose, which up until recently were known to inhibit xylanase activity. Emerging data, however, suggest that xylanases are able to accommodate acetyl side-groups within their catalytic site. In the present work, a fungal GH30 xylanase from Thermothelomyces thermophila, namely TtXyn30A, was shown to release acetylated xylobiose when acting on pretreated lignocellulosic substrate. The released disaccharides could be acetylated at the 2-OH, 3-OH or both positions of the non-reducing end xylose, but the existence of the acetylation on the reducing end cannot be excluded. The synergy of TtXyn30A with acetyl esterases indicates that particular subsites within its active site cannot tolerate acetylated xylopyranose residues. Molecular docking showed that acetyl group can be accommodated on the 2- or 3-OH position of the non-reducing end xylose, unlike the reducing-end xylose (subsite −1), where only 3-OH decoration can be accommodated. Such insight into the catalytic activity of TtXyn30A could contribute to a better understanding of its biological role and thus lead to a more sufficient biotechnological utilization.

Comparison of organosolv pretreatment of masson pine with different solvents in promoting delignification and enzymatic hydrolysis efficiency

Organosolv pretreatment has been verified to facilitate the enzymatic hydrolysis by efficient delignification. Recently, novel solvents derived from biomass have been applied in lignocellulose pretreatment. However, few studies on the pretreatment of softwood with novel solvents have been reported. In this study, organosolv pretreatments with three green solvents, including γ-valerolacton (GVL), tetrahydrofuran (THF), and 2-methyltetrahydrofuran (2-MTHF), were performed on masson pine, and compared with conventional ethanol (EtOH) pretreatment. The results showed that GVL pretreatment exhibited the best performance for removing lignins from masson pine, achieving a pretty high lignin removal ratio of 87.2 % at 150 °C with 75 mM H2SO4. Correspondingly, the highest glucose yield of 76.8 % was observed in the enzymatic hydrolysis of GVL pretreated masson pine with a relatively low cellulase loading (20 FPU/g glucan). The relations between relative energy difference of the solvent-lignin interactions and both of the lignin removal and enzymatic digestibility of organosolv pretreated substrates were evaluated. Furthermore, the structural features of four organosolv lignins were characterized, including molecular weights, functional groups, inter-unit linkages and aromatic information. The results provide a better understanding of organosolv pretreatment effects on enzymatic digestibility of softwood biomass, and give comprehensive lignin properties for valorization of organosolv lignins from softwood.

Application of response surface methodology (RSM) for optimizing methane yield of oxidative pretreated Xyris capensis

This study investigated the application of Response Surface Methodology (RSM) for optimizing and predicting methane yield from oxidative pretreated Xyris capensis. Input process parameters of retention time, temperature, and pretreatment condition were considered, with methane yield as the response. The results show that all three process parameters selected significantly influence methane yield, and analysis of variance (ANOVA) indicates that the RSM model is significant for the study. A correlation coefficient (R2) of 0.9071 was recorded, which implies that the model has 91% prediction accuracy. Interactive influence of temperature and retention time, pretreatment and retention time, and pretreatment and temperature were significant to methane release. Optimum conditions for methane release from RSM model are 14 days retention time, 25 °C temperature, and pretreatment condition of 85% H2O2 and 15% H2SO4 with daily optimum methane yield of 32.65 mLCH4 /gVSadded. This study shows that RSM is suitable for methane yield optimization and prediction during the anaerobic digestion of oxidative pretreated lignocellulose substrates.

Proteases for obtaining of food protein hydrolysates from proteinaceous by-products

Due to the increasing shortage of food protein in the world, the most effective and complete use of proteinaceous substrates is an urgent task. The most promising way to utilize secondary protein-containing raw materials is to increase its nutritional value through enzymatic hydrolysis. The use of protein hydrolysates obtained from protein-containing by-products has great potential in various areas of the food industry, as well as in the production of foods for medical and special dietary uses. The aim of the research was to propose optimal methods for processing protein substrates to obtain hydrolysates with desired properties, taking into account the characteristics of the main types of proteinaceous by-products and the specificity of proteases used. Material and methods. We used the data contained in PubMed, WoS, Scopus, and eLIBRARY.RU databases, which meet the requirements of scientific reliability and completeness. Results. Collagen-containing wastes from the meat, poultry and fish processing industries, whey, soy protein and gluten are the main types of protein-containing by-products successfully used to produce food and functional hydrolysates. The molecular structure, basic biological and physico-chemical properties of collagen, whey proteins, various protein fractions of wheat gluten and soy protein are described. The expediency of enzymatic treatment of protein-containing by-products using proteases is shown to reduce antigenicity and eliminate anti-nutritional properties, improve nutritional, functional, organoleptic and bioactive properties for subsequent use in food production, including those for medical and special dietary uses. Information is presented on the classification of proteolytic enzymes, their main properties, and the effectiveness of their use in the processing of various types of proteinaceous by-products. Conclusion. Based on the literature data analysis, the most promising methods for obtaining food protein hydrolysates from secondary protein-containing raw materials are proposed, including pretreatment of substrates and the selection of proteolytic enzymes with a certain specificity.

Influence of fruits and vegetable waste pre-treatment on black soldier fly larval growth

Hermetia illuciens, commonly known as black soldier fly (BSF) can convert organic biomass into manure and insect biomass into protein and fat. Currently, in the waste management industry, BSF larvae are predominantly used to convert valorized organic substrates into fertilizer and to produce biogas. They are also alternatively used as viable protein substitutes for animal feed as well as human consumer products. The treatment of organic wastes before BSFL consumption indicated a positive stimulation in the biomass conversion rate, larval growth rate and overall larval performance parameters. The current study was designed to analyze the effect of the bio-stimulation-based pre-treatment strategy of the feed on performance parameters, such as larval weight, larval survival rate, substrate reduction by pre-treatment of biowaste for better growth, efficient performance, and good biomass composition in BSFL. In our study, we noticed significant up- and downregulation of several larval parameters by assessing substrate composition, larval growth parameters and substrate reduction rate. The bio-stimulated waste showed larval weight gain when compared to larvae grown in control feed. The heat pretreated waste was not suitable for larval growth as the parameters assessed were observed to be declined. Further investigations are needed to comprehend how BSFL reared on pretreated substrates enhances the nutritional composition of larvae.

Biosurfactants from renewable sources - A review

Biosurfactants have wide applications in pharmaceutical, agriculture and food industries. The research area of biosurfactants is gaining immense attention. The review mentions here the advantages and various substrates used for biosurfactants production. The pre-treatment of substrates for biosurfactants production is also focused. The production of biosurfactants by solid state fermentation is also described. The renewable substrates, yield and microorganisms used for biosurfactant production are also taken into consideration. The screening methods for biosurfactant are also described. The use of renewable sources for biosurfactant production is specially focused in the review. This will be very eco-friendly, easy and economical. More studies need to BE done on large-scale production of biosurfactants using genetically engineered microorganisms.

Effect of addition of certain substances during slurry preparation to optimize biogas production

Biogas from anaerobic digestion of organic substance has become the available replacement for the fossil fuel. This research was carried out to investigate the effect of certain substances added during slurry preparation to enhance biogas formation. The biodigester was locally fabricated using plastic container of 25liter capacity. The slurry was prepared by adding Calcium Sulphate, Chopped plantain leaf, and pretreated substrate. After 15 days of anaerobic fermentation, the slurry with CaSO4 gave more biogas of 0.403kg followed by the pretreated which gave 0.270kg. The one with plantain leaf gave the least biogas. This is as a result of inhibition of enzyme activity by certain chemical substance from the leaf. Also, the amount of Calcium sulphate to be added should not exceed 200g to 1kg of substrate to be used for slurry preparation.

Effect of Substrate Pretreatment Process on the Cutting Performance of Diamond-Coated PCB Micro-Milling Tools

Diamond coatings were deposited on PCB (printed circuit board) carbide milling tool substrates under various schemes of acid and alkali pretreatment by hot filament chemical vapor deposition (HFCVD). Scanning electron microscopy and X-ray coating analysis were used to examine the surface morphology of the milling tools and the impact of de-cobalt from the substrate surface after pretreatment. Milling experiments were carried out to study the cutting performance of diamond-coated PCB micro-milling tools under various pretreatment processes. The results show that abrasive wear, coating flaking, and cutting-edge chipping are the main failure forms of coated PCB milling tools. The substrate pretreatment process with 20 min of alkali etching followed by 20 s of acid etching allows the diamond-coated micro-milling tools to produce the best film-substrate adhesion and substrate strength. These milling tools also have the longest service lives and are suitable for the high-speed cutting processing of PCB.

Growth of ultrathin Bi2Se3 films by molecular beam epitaxy

Bi 2 Se 3 is a widely studied 3D topological insulator having potential applications in optics, electronics, and spintronics. When the thickness of these films decreases to less than approximately 6 nm, the top and bottom surface states couple, resulting in the opening of a small gap at the Dirac point. In the 2D limit, Bi2Se3 may exhibit quantum spin Hall states. However, growing coalesced ultrathin Bi2Se3 films with a controllable thickness and typical triangular domain morphology in the few nanometer range is challenging. Here, we explore the growth of Bi2Se3 films having thicknesses down to 4 nm on sapphire substrates using molecular beam epitaxy that were then characterized with Hall measurements, atomic force microscopy, and Raman imaging. We find that substrate pretreatment—growing and decomposing a few layers of Bi2Se3 before the actual deposition—is critical to obtaining a completely coalesced film. In addition, higher growth rates and lower substrate temperatures led to improvement in surface roughness, in contrast to what is observed for conventional epitaxy. Overall, coalesced ultrathin Bi2Se3 films with lower surface roughness enable thickness-dependent studies across the transition from a 3D-topological insulator to one with gapped surface states in the 2D regime.

A Combined Study on Optimization, In Silico Modeling, and Genetic Modification of Large Scale Microbial Cellulase Production.

Cellulase is a biocatalyst that hydrolyzes cellulosic biomass and is considered a major group of industrial enzymes for its applications. Extensive work has been done on microbial cellulase but fungi are considered a novel strain for their maximum cellulase production. Production cost and novel microbial strains are major challenges for its improvement where cheap agro wastes can be essential sources of cellulose as substrates. The researcher searches for more cellulolytic microbes from natural sources but the production level of isolated strains is comparatively low. So genetic modification or mutation can be employed for large-scale cellulase production before optimization. After genetic modification than in silico molecular modeling can be evaluated for substrate molecule's binding affinity. In this review, we focus not only on the conventional methods of cellulase production but also on modern biotechnological approaches applied to cellulase production by a sequential study on common cellulase-producing microbes, modified microbes, culture media, carbon sources, substrate pretreatment process, and the importance of optimum pH and temperature on fermentation. In this review, we also compare different cellulase activity determination methods. As a result, this review provides insights into the interrelationship between the characteristics of optimizing different culture conditions, genetic modification, and in silico enzyme modeling for the production of cellulase enzymes, which may aid in the advancement of large-scale integrated enzyme manufacturing of substrate-specific enzymes.

Cost-effective equipment for surface pre-treatment for cleaning and excitation of substrates in semiconductor technology

This article presents a cost-effective ultraviolet-ozone cleaner (UV/O3 Cleaner) for surface pre-treatment of substrates in the field of semiconductor technology. The cleaner consists of two chambers, the upper one contains the electronics, including the time counter. The lower chamber contains the two UV sterilisation lamps and a UV reflector of anodized aluminium, which confines the area of high Ozone concentration in the area of interest. The device is successfully used for surface cleaning and modification of different materials. To this end, the two important wavelengths 253.7 nm (excitation of organic residues) and 184.9 nm (production of ozone from the atmospheric environment as a strong oxidant) were first detected. The effectiveness of UV/O3 cleaning is demonstrated by improving the properties of indium tin oxide (ITO) for OLED fabrication. The contact angle of water to ITO could be reduced from 90° to 3° and for diiodomethane, it was reduced from 55° to 31° within the 10 min of irradiation. This greatly improved wettability for polar and non-polar liquids can increase the flexibility in further process control. In addition, an improvement in wettability is characterized by measuring the contact angles for titanium dioxide (TiO2) and polydimethylsiloxane (PDMS). The contact angle of water to TiO2 decreased from 70° to 10°, and that of diiodomethane to TiO2 from 54° to 31°. The wettability of PDMS was also greatly increased. Here, the contact angle of water was reduced from 109° to 24° and the contact angle to diiodomethane from 89° to 49°.Article HighlightsWe report a cost-effective dry-cleaning device for surface cleaning and modification based on ultraviolet-ozone irradiation.Contact angle measurements show an increase of wettability for different materials due to surface modification.The UVO3 pre-treatment improves layer formation and optoelectrical properties of OLEDs.

Efficient fractionation and targeted valorization of industrial xylose residue by synergistic and mild alkaline deep eutectic solvent‑hydrogen peroxide pretreatment

Achieving efficient fractionation and tailored downstream high value-added applications of bulk industrial waste biomass could guarantee the sustainability of biorefinery strategies. A synergistic and mild alkaline deep eutectic solvent‑hydrogen peroxide (DES-HP) pretreatment was designed in this study to significantly reduce pretreatment costs while achieving efficient fractionation of industrial xylose residues for preparing high antioxidative lignin and high enzymatic digestion of cellulose substrates for subsequent bioenergy and biochemicals production. The results demonstrated that this DES-HP pretreatment had admirable biomass deconstruction ability and the obtained DES-HP lignin displayed well-preserved structures and excellent antioxidative properties, which facilitated downstream catalytic degradation as well as the production of lignin-based materials and chemicals. Under the optimal condition (60 °C, 2 h, 10 FPU/g), the fermentable glucose yield of the DES-HP pretreated substrate could achieve 95.89%. In conclusion, this synergistic DES-HP is an ideal pretreatment strategy for the current tailored biorefinery scenario of industrial lignocellulosic biomass.

The Relationship between Structural Features of Lignocellulosic Materials and Ethanol Production Yield

Lignocellulosic materials are a mixture of natural polymers which can be considered a great alternative source of chemical products and energy. Hence, pinewood, poplar wood, and rice straw, as representatives of different types of lignocelluloses, were subjected to several pretreatment types in order to increase ethanol production yield. All pretreatments increased enzymatic hydrolysis and ethanol yield, specifically pretreatment with phosphoric acid. This pretreatment increased ethanol yields by 304.6% and 273.61% for poplar wood and pinewood, respectively, compared to untreated substrates. In addition, a number of analyses, including a BET test, buffering capacity, crystallinity, accessible surface area, and composition measurement, were conducted on the pretreated substrates to investigate their structural modifications in detail. Accessible surface area, as one of the most important parameters for performance of enzymes and microorganisms in the fermentation process, was examined by the water retention value test. The results of this method (using centrifuge) showed that the maximum accessible surface area was related to the pretreated samples with phosphoric acid so that it increased WRV to 132.19%, 149.41%, and 68.44% for poplar wood, pinewood, and rice straw, respectively, as compared to untreated substrates. On the whole, pretreatments restructured and opened up the tangled structure of lignocelluloses, resulting in a considerable increase in ethanol yields. Moreover, in this study, for the first time, a new correlation was presented for each substrate which indicates the relationship between ethanol yield and structural features of the lignocellulosic substrate.

In-situ lignin sulfonation for enhancing enzymatic hydrolysis of poplar using mild organic solvent pretreatment

Biomass pretreatment is an essential strategy to overcome biomass recalcitrance and promote lignocellulosic bioconversion. Here, a reusable organic solvent system (formic acid-methanesulfonic acid) was explored to pretreat poplar under a mild temperature (below 100 °C). The results showed that the co-solvent system could extract basically complete hemicelluloses and part of lignin with original cellulose retained in the pretreated substrates. Meanwhile, sulfonic acid groups were introduced into lignin structure remained in the substrates. The glucose conversion yield of the substrates with a higher concentration of sulfonic acid groups (13.2 mmol/kg) reached 45.9 % by reducing the hydrophobic interaction between lignin and cellulase, showing 89.3 % improvement compared with that of the substrates treated with single formic acid. This progressive study aimed to develop a new strategy to realize sulfonation and promote enzymatic hydrolysis of substrates by using mild organic solvent pretreatment.

Crystallinity improvement of room-temperature PLD-deposited ZnO thin films on cyclo-olefin polymer substrates subject to surface-pretreatment with vacuum-UV-light irradiation

The effect of the surface-pretreatment of cyclo-olefin polymer (COP) substrates with vacuum-ultraviolet (VUV) light irradiation on the crystal growth of ZnO thin films deposited by room-temperature pulsed laser deposition (PLD) was investigated for development of flexible optical devices. 172-nm-excimer light irradiation with durations of 60 to 600 s in air was found to make the COP surface more hydrophilic and smooth. It was verified from measurements of X-ray diffraction, atomic force microscope and high-resolution transmission electron microscope that the ZnO thin films grown on the VUV-light-pretreated COP substrates exhibited enhanced (0001) orientation growth and increased crystallinity compared with the samples grown on substrates not subject to the pretreatment; the samples on the pretreated substrates also showed a smooth surface and atomically sharp interface between the thin film and the substrate. The electrical resistivity of the ZnO thin film grown on the VUV-light-pretreated COP substrate was estimated to be 2.3 × 10−3 Ωcm, which was 40% lower than that of the film grown on the untreated substrate.

Understanding the impact of steam pretreatment severity on cellulose ultrastructure, recalcitrance, and hydrolyzability of Norway spruce

The efficient use of softwood in biorefineries requires harsh pretreatment conditions to overcome biomass recalcitrance. Following harsh pretreatments, the hemicellulose is solubilized. Here, we studied the material characteristics of Norway spruce following steam pretreatment at six different severities, relating chemical and structural information to the enzymatic hydrolyzability. Steam pretreatment conditions were defined by two different temperatures (180 °C and 210 °C), with and without the addition of various acids (CH3COOH, H3PO4, H2SO4, SO2). Structural knowledge of the streams is a cornerstone for developing an efficient saccharification process.This study combines advanced structural characterizations to gain fundamental understanding of the influence of severity of pretreatment on spruce. Structural knowledge is a cornerstone in developing an effective saccharification process by modulating pretreatment conditions and enzymes employed.Overall structural properties were assessed by scanning electron microscopy. The effect of stream pretreatment severity on lignin and lignin-carbohydrate bonds was investigated by two-dimensional heteronuclear single quantum correlation nuclear magnetic resonance. Finally, cellulose ultrastructure was studied by applying small/wide-angle X-ray scattering. The structural characteristics of the six pretreated softwood substrates were related to the enzymatic hydrolyzability.With increasing pretreatment severity, surface defibrillation, and lignin depolymeryzation were observed. Further, lignin-carbohydrate complexes signals were detected. Cellulose analysis revealed the rearrangement of microfibrils leading to the formation of larger microfibril aggregates. This microfibril rearrangement likely contributed to the observed increase in enzymatic hydrolysis yields as better enzyme accessibility resulted.

Biotransformation of Agricultural Wastes into Lovastatin and Optimization of a Fermentation Process Using Response Surface Methodology (RSM)

Lovastatin is a competitive inhibitor of the enzyme 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA Reductase). The HMG-CoA reductase is responsible for the production of mevalonate by the reduction of HMG-CoA. It is a rate-limiting step in the production of cholesterol. The current study demonstrates the production of lovastatin from an ethidium bromide mutated strain of Aspergillus terreus ATE-120 (saprophytic fungus) that is grown on 1–3% NaOH pretreated substrate of sugar cane bagasse (Saccharum officinarum L.). For the hyperproduction of lovastatin, different optimization parameters such as temperature, pH, inoculum size, fermentation period, and inoculum age were mentioned and analyzed via response surface methodology. The RSM results indicate that the maximum lovastatin yield (156.43 mg/L) was predicted at a 5.5 pH, 35 °C temperature, 4 mL inoculum size, 36 h inoculum age, and 48 h fermentation via solid state fermentation. According to these results, the effect of pH had a significant effect on lovastatin production, while other parameters had an insignificant effect, and coefficients of determination (R2) having a value of 77.24% indicates the goodness of the proposed model. The structure of the obtained drug was confirmed by nuclear magnetic resonance. Moreover, an X-ray diffraction analysis of the sample was carried out to characterize the physical form of the lovastatin. It can be concluded from the above study that the maximum yield of the drug can be found via RSM and that the selected strain (Aspergillus terreus ATE-120) has good potential for lovastatin production through solid-state fermentation.

Microstructure and Surface Topography Study of Nanolayered TiAlN/CrN Hard Coating

The microstructure and surface topography of PVD hard coatings are among the most important properties, as they significantly determine their mechanical, tribological and other properties. In this study, we systematically analyzed the microstructure and topography of a TiAlN/CrN nanolayer coating (NL-TiAlN/CrN), not only because such coatings possess better mechanical and tribological properties than TiAlN and CrN monolayer coatings, mainly because the contours of the individual layers, in the cross-sectional STEM or SEM images of such coatings, make it easier to follow topographic and microstructural changes that occurred during its growth. We investigated the effects of the substrate rotation modes on the microstructure and surface topography of the NL-TiAlN/CrN coating, as well as on the periodicity of the nanolayer structure. The influence of the substrate material and the ion etching methods were also studied, while special attention was given to the interlayer roughness and influence of non-metallic inclusions in the steel substrates on the growth of the coating. The topographical features of the NL-TiAlN/CrN coating surface are correlated with the observations from the cross-sectional TEM and FIB analysis. Selected non-metallic inclusions, covered by the NL-TiAlN/CrN coating, were prepared for SEM and STEM analyses by the focused ion beam. The same inclusions were analyzed prior to and after deposition. We found that substrate rotation modes substantially influence the microstructure, surface topography and periodicity of the NL-TiAlN/CrN layer. Non-metallic inclusions in the substrates cause the formation of shallow craters or protrusions, depending on their net removal rates during the substrate pretreatment (polishing and ion etching), as compared to the matrix.