The high externalized and still partly unknown costs of fossil fuels through air pollution from combustion, and their limited resources have caused mankind to (re)turn to renewable sources such as wind, solar, and biomass to meet its energy needs. Converting biomass to synthesis gas is advantageous since it can utilize a wide variety of (waste) feedstocks to obtain an energetic and versatile product at low cost in large quantities. Gasification is no new technology; yet in recent years, biomass gasification has attracted significant attention. Due to the non-depletable nature of agricultural waste and similar biomass side streams, which have little value and can bring environmental problems when mismanaged such as methane emissions, it is possible to obtain cheap electrical or thermal energy through the gas produced with high efficiencies. Combined heat and power (CHP) is the preferred use case, and recently the focus has moved to polygeneration, e.g., to make value-added products from the synthesis gas. Fischer–Tropsch synthesis from coal-derived syngas is now being complemented by the gas fermentation of biobased synthesis gas, where microorganisms yield materials from CO/H2 (and CO2) in an anaerobic process and from CH4/O2 in an aerobic process. Syngas methanation offers an alternative route to produce synthetic natural gas (SNG, or bio-SNG) as additional feedstock for gas fermentation. Materials made from syngas are decoupled from primary agricultural operations and do not compete with feed and food production. Due to the ample raw material base for gasification, which can basically be all kinds of mostly dry biomass, including waste such as municipal solid waste (MSW), syngas-derived products are highly scalable. Amongst them are bioplastics, biofuels, biobased building blocks, and single-cell protein (SCP) for feed and food. This article reviews the state-of-the-art in biomass gasification with a spotlight on gas fermentation for the sustainable production of high-volume materials.
P3HB (poly-β-hydroxybutyrate), an energy-storage compound of several microorganisms, can be used as bioplastics material. P3HB is completely biodegradable under aerobic and aerobic conditions, also in the marine environment. The intracellular agglomeration of P3HB was examined employing a methanotrophic consortium. Supplanting fossil, non-degradable polymers by P3HB can significantly reduce the environmental impact of plastics. Utilizing inexpensive carbon sources like CH 4 (natural gas, biogas) is a fundamental methodology to make P3HB production less costly, and to avoid the use of primary agricultural products such as sugar or starch. Biomass growth in polyhydroxyalkanoates (PHA) in general and in Poly (3-hydroxybutyrate) manufacture in specific could be a foremost point, so here the authors focus on natural gas as a proper carbon source and on the selection of bioreactors to produceP3HB, and in future further PHA, from that substrate. CH 4 can also be obtained from biomass, e.g., biogas, syngas methanation or power-to-gas (synthetic natural gas, SNG). Simulation software can be utilized for examination, optimizing and scale-up of the process as shown in this paper. The fermentation systems continuously stirred tank reactor (CSTR), forced-liquid vertical loop bioreactor (VTLB), forced-liquid horizontal tubular loop bioreactor (HTLB), airlift (AL) fermenter and bubble column (BC) fermenter were compared for their methane conversion, kLa value, productivity, advantages and disadvantages. Methane is compared to methanol and other feedstocks. It was discovered that under optimum processing circumstances and using Methylocystis hirsuta , the cells accumulated 51.6% cell dry mass of P3HB in the VTLB setup.
Abstract Various stress factors affect the physiology of cattle. Environmental stressors include heat, cold, wind, humidity, nutrition, endocrine disruptors, and management. Several negative health effects are associated with the hormones produced under stress conditions. In cattle, cortisol has been associated with reduced rates of reproduction, lowered milk production, and suppression of the immune system causing greater disease susceptibility. For a better understanding of how stress hormones impact feed digestibility and animal performance, this review has been divided into four sections (feed digestibility, milk production, milk composition, and meat quality). In dairy cows, the transition period is challenging because of a shortage of energy and nutrients, inflammation, increased lipid peroxidation, as well as hormonal and metabolic changes. Stress hormones decrease milk yield, but cortisol affects arteriovenous pressure, which is essential for milk production (due to stressful conditions or other factors such as the use of steroid medicines). Higher cortisol levels have been observed in the hotter and more stressful months of the year. On the other hand, in early lactation, reduced feed intake can lead to acidosis, reduced milk fat, and lameness in cattle. Heat stress (HS) influences milk composition negatively, especially a decrease in milk protein. In fattening animals, HS reduces feed intake, animal growth, and production efficiency. These extreme events have short-term effects and can last a day or two. Practical solutions can be adopted to reduce HS by modifying the diet, increasing the amount of water for drinking, providing shade, and a good air exchange in the barn and installing sprinklers. It is possible to increase animal welfare and product quality based on the conclusions of this review.
Bioplastics hold significant promise in replacing conventional plastic materials, linked to various serious issues such as fossil resource consumption, microplastic formation, non-degradability, and limited end-of-life options. Among bioplastics, polyhydroxyalkanoates (PHA) emerge as an intriguing class, with poly(3-hydroxybutyrate) (P3HB) being the most utilized. The extensive application of P3HB encounters a challenge due to its high production costs, prompting the investigation of sustainable alternatives, including the utilization of waste and new production routes involving CO2 and CH4. This study provides a valuable comparison of two P3HBs synthesized through distinct routes: one via cyanobacteria (Synechocystis sp. PCC 6714) for photoautotrophic production and the other via methanotrophic bacteria (Methylocystis sp. GB 25) for chemoautotrophic growth. This research evaluates the thermal and mechanical properties, including the aging effect over 21 days, demonstrating that both P3HBs are comparable, exhibiting physical properties similar to standard P3HBs. The results highlight the promising potential of P3HBs obtained through alternative routes as biomaterials, thereby contributing to the transition toward more sustainable alternatives to fossil polymers.
Consumer Fused Filament Fabrication (FFF) desktop 3D printers are used for prototyping, spare parts and even smallscale production, but produce parts with lower tensile strength than traditional manufacturing methods. High tensile continuous fibers increase filament composite strength, but poor fiber adhesion and pull-out are common weaknesses. The few commercially available continuous fiber reinforced (CFR) filaments are costly and only compatible with their manufacturer’s machines.
This work describes the development of a method and a prototype apparatus to produce standardized CFR filament, addressing the weaknesses of CFR thermoplastics while maintaining their compatibility with consumer 3D printers, and thereby achieving mechanical properties required for costeffective small-scale productions.
A bundle of raw carbon fiber is impregnated with a solution of thermoplastic and compatible solvent, improving the adhesion of the fibers to the thermoplastic and reducing fiber pull-out. The pretreated fiber is then extrusion-coated with thermoplastic to achieve a standardized filament diameter. 1.75 mm PLA filament reinforced with 12k continuous carbon fiber and pretreated with an ABS- Acetone solution was produced.
Parts and products ranging from small consumer goods to meter- sized airplane wing sections were successfully printed using a standard FFF extruder. Tensile tests showed a yield stress increase of 535% compared to plain PLA, and a 70% increase compared to filament produced with raw, untreated fibers. Further work is needed to determine the ideal fiber content, its distribution within the filament and the concentration of the solution.
With the buried tunnel junctions technology a breakthrough in the dynamic and stationary losing performance has been achieved for long-wavelength InP-based VCSELs making these lasers ideally suited for broadband communications and gas sensing applications.
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