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"Continuous production"
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Production of L-alanyl-L-glutamine by immobilized Escherichia coli expressing amino acid ester acyltransferase
Production of Ala-Gln by the E. coli expressing α-amino acid ester acyltransferase was a promising technical route due to its high enzyme activity, but the continuous production ability still needs to improve. Therefore, the immobilized E. coli expressing α-amino acid ester acyltransferase was applied for the continuous production of Ala-Gln. Four materials were selected as embedding medium for the whole cell entrapment of recombinant bacteria. Calcium alginate beads were found to be the most proper entrapment carrier for production of Ala-Gln. The temperature, pH, and repeatability of the immobilized cell were compared with free cells. Results showed that immobilization cell could maintain a wider range of temperature/pH and better stability than free cell (20–35 °C/pH 8.0–9.0, and 25 °C/pH 8.5, respectively). On this basis, continuous production strategy was put forward by filling the immobilized cell in the tubular reactor with multiple control conditions. The Ala-Gln by immobilization cell achieved the productivity of 2.79 mg/(min*mL-CV) without intermittent time. Consequently, these findings suggest that the immobilization technique has potential applications in the production of Ala-Gln by biotechnological method.Key points• Immobilization helps to achieve high efficiency production of Ala-Gln.• Immobilized cells have better stability than free cells.• Sodium alginate is the most suitable immobilized material.
Journal Article
How to succeed with continuous improvement : a primer for becoming the best in the world
\"The all-you-need-to-know primer on continuous improvement--offering best practices presented in a comprehensive, detailed case study illustrating what works and what doesn'tHow to Succeed with Continuous Improvement takes the reader through a real-life case study of one organization's journey towards a world-class continuous improvement process. It provides practical advice on methods, tools, and leadership to help operations professionals set up, execute, and continuously build upon their organization's improvement work.The book offers specific advice and practical application on how to get all employees to give maximum contributions by using their ideas to improve the organization. Each chapter details part of the transformation story and then reflects on and analyzes each concept of continuous improvement illustrated. Joakim Ahlstrom is Head of Consulting for C2, a firm that helps companies establish continuous improvements that provide measurable results. \"-- Provided by publisher.
Book
Continuous production of poly(R-3-hydroxybutyrate) by Cupriavidus necator in a multistage bioreactor cascade
Poly(hydroxyalkanoates) (PHAs) constitute biodegradable polyesters and are considered among the most promising candidates to replace common petrochemical plastics in various applications. To date, all commercial processes for PHA production employ microbial discontinuous fed-batch fermentations. These processes feature drawbacks such as varying product quality and the inevitable periods of downtime for preparation and post-treatment of the bioreactor equipment. An unprecedented approach to PHA production was chosen in the presented work using a multistage system consisting of five continuous stirred tank reactors in series (5-SCR), which can be considered as a process engineering substitute of a continuous tubular plug flow reactor. The first stage of the reactor cascade is the site of balanced bacterial growth; thereafter, the fermentation broth is continuously fed from the first into the subsequent reactors, where PHA accumulation takes place under nitrogen-limiting conditions. Cupriavidus necator was used as production strain. The focus of the experimental work was devoted to the development of a PHA production process characterized by high productivity and high intracellular polymer content. The results of the experimental work with the reactor cascade demonstrated its potential in terms of volumetric and specific productivity (1.85 g L^sup -1^ h^sup -1^ and 0.100 g g^sup -1^ h^sup -1^, respectively), polymer content (77%, w/w) and polymer properties (M ^sub w^=665 kg/mol, PDI=2.6). Thus, implementing the technology for 5-SCR production of PHB results in an economically viable process. The study compares the outcome of the work with literature data from continuous two-stage PHA production and industrial PHA production in fed-batch mode.[PUBLICATION ABSTRACT]
Journal Article
A Novel Energy-Intensity Model Based on Time Scale for Quasi-Continuous Production in Iron and Steel Industry
Energy intensity is an important assessment indicator of energy consumption. Unfortunately, the traditional energy intensity model (TEIM) has obvious limitations when applied to quasi- continuous production process, especially for small time scales (STS). Therefore, a novel energy intensity model (NEIM) has been established in this study. The NEIM includes three main stages. Firstly, the statistical period and time scale have been determined. Secondly, the concept of workpiece valid weight has been proposed for a given time scale. Then the specific calculation method has also been established. Thirdly, a NEIM has been suggested according to the definition of energy intensity. The application results for a reheating furnace show that the NEIM’s effectiveness has been verified via comparison with the TEIM for large time scale (LTS) and critical time scale (CTS), whereas the NEIM still has validity at STS. Additionally, calculation results for the NEIM reflect more trend information at LTS and CTS; whereas, more dynamic information has been reflected at STS. The aim of this research was to expand the NEIM application for different time scales. Meanwhile, NEIM can also be applied to various energy-consuming facilities.
Journal Article
Continuous-Flow Production of Liposomes with a Millireactor under Varying Fluidic Conditions
Continuous-flow production of liposomes using microfluidic reactors has demonstrated advantages compared to batch methods, including greater control over liposome size and size distribution and reduced reliance on post-production processing steps. However, the use of microfluidic technology for the production of nanoscale vesicular systems (such as liposomes) has not been fully translated to industrial scale yet. This may be due to limitations of microfluidic-based reactors, such as low production rates, limited lifetimes, and high manufacturing costs. In this study, we investigated the potential of millimeter-scale flow reactors (or millireactors) with a serpentine-like architecture, as a scalable and cost-effective route to the production of nanoscale liposomes. The effects on liposome size of varying inlet flow rates, lipid type and concentration, storage conditions, and temperature were investigated. Liposome size (i.e., mean diameter) and size dispersity were characterised by dynamic light scattering (DLS); z-potential measurements and TEM imaging were also carried out on selected liposome batches. It was found that the lipid type and concentration, together with the inlet flow settings, had significant effects on the properties of the resultant liposome dispersion. Notably, the millifluidic reactor was able to generate liposomes with size and dispersity ranging from 54 to 272 nm, and from 0.04 to 0.52 respectively, at operating flow rates between 1 and 10 mL/min. Moreover, when compared to a batch ethanol-injection method, the millireactor generated liposomes with a more therapeutically relevant size and size dispersity.
Journal Article
Continuous Production of Ethanol, 1-Butanol and 1-Hexanol from CO with a Synthetic Co-Culture of Clostridia Applying a Cascade of Stirred-Tank Bioreactors
Syngas fermentation with clostridial co-cultures is promising for the conversion of CO to alcohols. A CO sensitivity study with Clostridium kluyveri monocultures in batch operated stirred-tank bioreactors revealed total growth inhibition of C. kluyveri already at 100 mbar CO, but stable biomass concentrations and ongoing chain elongation at 800 mbar CO. On/off-gassing with CO indicated a reversible inhibition of C. kluyveri. A continuous supply of sulfide led to increased autotrophic growth and ethanol formation by Clostridium carboxidivorans even at unfavorable low CO concentrations. Based on these results, a continuously operated cascade of two stirred-tank reactors was established with a synthetic co-culture of both Clostridia. An amount of 100 mbar CO and additional sulfide supply enabled growth and chain elongation in the first bioreactor, whereas 800 mbar CO resulted in an efficient reduction of organic acids and de-novo synthesis of C2-C6 alcohols in the second reactor. High alcohol/acid ratios of 4.5–9.1 (w/w) were achieved in the steady state of the cascade process, and the space-time yields of the alcohols produced were improved by factors of 1.9–5.3 compared to a batch process. Further improvement of continuous production of medium chain alcohols from CO may be possible by applying less CO-sensitive chain-elongating bacteria in co-cultures.
Journal Article
Continuous Production of Water-Borne Polyurethanes: A Review
Water-borne polyurethanes are novel functional polymers that use water as the dispersion medium. When compared with solvent-borne polyurethanes, water-borne polyurethanes are more environmentally friendly and easier to transport and store. Water-borne polyurethanes have attracted increasing attention due to their extensive applications in plastics, paints, adhesives, inks, biomaterials, and other fields. In this study, the characteristics of water-borne polyurethanes were discussed, followed by a review of studies detailing reaction procedures and mechanisms for their continuous production. Additionally, current and future applications of continuous production processes for water-borne polyurethanes are presented.
Journal Article
Fast and scalable production of crosslinked polyimide aerogel fibers for ultrathin thermoregulating clothes
Polyimide aerogel fibers hold promise for intelligent thermal management fabrics, but their scalable production faces challenges due to the sluggish gelation kinetics and the weak backbone strength. Herein, a strategy is developed for fast and scalable fabrication of crosslinked polyimide (CPI) aerogel fibers by wet-spinning and ambient pressure drying via UV-enhanced dynamic gelation strategy. This strategy enables fast sol-gel transition of photosensitive polyimide, resulting in a strongly-crosslinked gel skeleton that effectively maintains the fiber shape and porous nanostructure. Continuous production of CPI aerogel fibers (length of hundreds of meters) with high specific modulus (390.9 kN m kg
−1
) can be achieved within 7 h, more efficiently than previous methods (>48 h). Moreover, the CPI aerogel fabric demonstrates almost the same thermal insulating performance as down, but is about 1/8 the thickness of down. The strategy opens a promisingly wide-space for fast and scalable fabrication of ultrathin fabrics for personal thermal management.
The scalable production of polyimide aerogel fibers, promising intelligent thermal management fabrics, is limited by the slow gelation kinetics and the weak backbone. Here, the authors present a UV-enhanced dynamic gelation strategy for fast and scalable preparation of cross-linked polyimide aerogel fibers by wet spinning and cost-effective ambient pressure drying.
Journal Article
Continuously processing waste lignin into high-value carbon nanotube fibers
High value utilization of renewable biomass materials is of great significance to the sustainable development of human beings. For example, because biomass contains large amounts of carbon, they are ideal candidates for the preparation of carbon nanotube fibers. However, continuous preparation of such fibers using biomass as carbon source remains a huge challenge due to the complex chemical structure of the precursors. Here, we realize continuous preparation of high-performance carbon nanotube fibers from lignin by solvent dispersion, high-temperature pyrolysis, catalytic synthesis, and assembly. The fibers exhibit a tensile strength of 1.33 GPa and an electrical conductivity of 1.19 × 10
5
S m
−1
, superior to that of most biomass-derived carbon materials to date. More importantly, we achieve continuous production rate of 120 m h
−1
. Our preparation method is extendable to other biomass materials and will greatly promote the high value application of biomass in a wide range of fields.
Towards high-value utilization of biomass materials, authors demonstrate continuous preparation of high-performance carbon nanotube fibers using lignin as carbon source by solvent dispersion, high-temperature pyrolysis, catalytic synthesis, and assembly.
Journal Article