Fast Circulation Research Articles

A multiphysics simulator for stope-coupled heat exchanger operation in deep underground mines

The ever-increasing mine depth offers unprecedented opportunities to access high-grade geothermal resources. By pre-installing pipeline systems in mined-out cavities before waste tailings placement, the stope-coupled heat exchanger (SCHE) has drawn growing attention for its superior socio-economic advantages. However, despite the extensive focus on energy efficiency, the system stability during heat production has been typically overlooked. This study therefore introduces a novel high-fidelity simulator for replicating practical SCHE operation. By embedding non-isothermal pipe flow into an evolutive thermo-poromechanics framework for cemented tailings, the outlet water temperature and multiphysics backfill response in diverse production settings are meticulously studied. Our calculations reveal for the first time that circulating chill fluid within mine backfill can substantially alleviate pressure development, suggesting enhanced system stability with heat-exchanger implementation. We also demonstrate that albeit targeting higher-grade geothermal resources, prioritizing cold-season operation, and pre-charging heat exchangers with production delays could spur heat productivity, the companion thermal pressure generation might still impose significant overloading risks. Conversely, while fast circulation would diminish the end-utilization temperature, the rapid heat removal could indeed facilitate superior efficiency and stability performance for the geothermal system. We believe these new findings hold critical implications for better positioning SCHE as a safely sustainable pathway towards hybrid utilization of deep resources.

Motivation and Economic Behavior Behind the Success of Trader Widows in Indonesia

Purpose: This article analyzes work motivation, forms of economic behavior, and success stories of widowed traders in Indonesia, especially in Sidrap, South Sulawesi. Methods: The research was conducted with a qualitative approach using naturalistic inquiry methods. The data used consists of primary and secondary data, which were collected through observation, interviews and document study. Results and Conclusion: The results of the study show that the motivation for widows in South Sulawesi to choose trading as their profession is the influence of the environment, where the majority of the population are traders, and the fast circulation of money. The economic behavior of trader widows includes distributing goods and utilizing profits for daily consumption needs, non-consumption needs, and saving for future needs, as well as for social activities and increasing capital. Research implications: The results of this research provide an overview of widows who have long been considered weak women and are often underestimated, who actually have high work motivation and have proven to be successful in trading. Originality/value: Widows should not be labeled as women who are weak and need mercy, but many of them are successful in developing businesses, including in the field of trade.

Hydrochemical Characterisation of Groundwaters in a Crystalline Basement Environment: The Case of Fractured Aquifers in the Poni Watershed in the South-West Region of Burkina Faso, West Africa

The Poni watershed is located in the south-west of Burkina Faso. Its geology is made up of fractured crystalline and crystallophyllian basement, where fractured aquifers are the most exploited for water needs. The aim of this study is to determine the physico-chemical characteristics of the groundwater in the fractured aquifers of the Poni watershed in order to gain a better understanding of the mineralisation processes and hydrochemical properties of the groundwater in these aquifers. To do this, approaches based on the determination of Calcite Saturation Indices (CSI) and Dolomite Saturation Indices (DSI), Principal Component Analysis (PCA) and hydrochemical properties show that the majority of groundwater in the basin is undersaturated with respect to carbonates (79.37%) and divided into three families in relation to circulation speed: very slow circulation water (20.63%), slow circulation water (55.56%) and fast circulation water (23.81%). The approaches also show that the mineralisation of groundwater in the basin is governed by the acid hydrolysis of minerals in the surrounding rocks, residence time and surface inputs. They are characterised by calcic and magnesian bicarbonate facies (85.7%), calcic bicarbonate facies (6.35%), sodium and potassium bicarbonate facies (1.59%) and calcic and magnesian sulphate chlorides (6.35%).

Experimental Work Of Development Of Information Culture Of Secondary Special Islamic Colleges

This article explains how information culture and its specific features in the modern era of information culture. The social factors that determine the lack of a critical approach to the selection of necessary information among students of a special Islamic educational college have been studied. Also, based on the fact that the acquisition of information culture is a vital necessity for future imams, the author made a number of proposals and recommendations in this regard. In the article in the information society, ensuring fast and high-quality circulation of information in the education system becomes the main criterion for the progress and development of the country, and also analyzes in detail the need for the effective use of information in the field of education. The main factors determining the level of formation of the information culture of students of secondary specialized Islamic education are explained. In the XXI century, every student, every teenager must meet the basic criteria of information culture; the problems of its use in the educational process and, of course, improving the culture of using the Internet are highlighted. The scientific article presents an analysis of studies conducted on the culture of using the Internet and social networks among students studying in secondary specialized educational institutions. This is a scientific study not only in Uzbekistan, but also in all countries of Central Asia; the formation of the information culture of students in secondary specialized Islamic educational colleges has not been studied at all. Formation criteria have been developed and explained in detail information culture of students studying in secondary specialized Islamic educational colleges.

The Level of Formation of The Information Culture of Islamic Students

This article explains what information culture is and its specific features in the era of modern information culture. Fast and high-quality circulation of information is needed in the educational system and is an important factor or aspect for the progress and development of a country. Therefore, it is important for students and the younger generation to implement the basic criteria of information culture in the proper use of the Internet in education. The research problem is to determine the social factors that lead to the lack of a critical approach to the selection of necessary information among students in Islamic educational institutions. This research is important because information culture is a vital need for future preachers or preachers. The research method uses a literature review approach. The focus of the research is to analyze the patterns of using information culture on the Internet and social media. The results of the study provide an explanation of the patterns of information use in society, especially in Islamic educational institutions. The results describe 13 key factors on the level of formation of students' information culture in Islamic education in the 21st century.
 Keywords: Information Culture, Islamic Education Institutions

ACTUAL PEDAGOGICAL ISSUES RELATED TO YOUTH INFORMATION CULTURE

This article explains how information culture and its specific features in the modern era of information culture. The social factors that determine the lack of a critical approach to the selection of necessary information among students of a special Islamic educational college have been studied. Also, based on the fact that the acquisition of information culture is a vital necessity for future imams, the author made a number of proposals and recommendations in this regard.
 In the article in the information society, ensuring fast and high-quality circulation of information in the education system becomes the main criterion for the progress and development of the country, and also analyzes in detail the need for the effective use of information in the field of education. 
 The scientific article presents an analysis of studies conducted on the culture of using the Internet and social networks among students studying in secondary specialized educational institutions. This is a scientific study not only in Uzbekistan, but also in all countries of Central Asia; the formation of the information culture of students in secondary specialized Islamic educational colleges has not been studied at all. Formation criteria have been developed and explained in detail information culture of students studying in secondary specialized Islamic educational colleges

B-247 Rapid and Field-deployable Microchip-based Real-time PCR for Hepatitis B Virus DNA Detection

Abstract Background Hepatitis B is one of the most common infectious diseases with global significance, seriously causing chronic liver complications and a heavy health burden in developing countries. There is no doubt that real-time polymerase chain reaction (RT-PCR) has been a golden standard for monitoring the Hepatitis B virus (HBV) level in clinical health management. However, the conventional PCR protocol cannot fulfill the field test requirement in some resource-poor areas due to its drawbacks, such as huge size, long turnaround time, and demand for professional laboratory facilities. For solving these problems, a portable microfluidic chip-based PCR detection system was developed to enable the nucleic acid test in a flexible, rapid, and economical way. With the efficient temperature control module and advanced optical path design, this novel panel can achieve fast thermal circulation with a 30°C/s heating rate and multiple fluorescent detection with a throughput of 6 samples at a time. Methods In this study, we assessed the detection performance of the system using a commercial HBV nucleic acid detection kit. The reproducibility, limit-of-detection (LoD), and linearity were validated by reference samples with gradient concentrations. We evaluated the clinical sensitivity and specificity of the microdevice by a total of 200 extracted serum samples (100 positive and 100 negative cases). The analytical results were compared with a traditional PCR device with FDA certification. Results The variation coefficients of the microdevice for reference samples with different concentrations are 1.78%, 1.98%, and 1.50% (n = 10), respectively. The field-deployable PCR system can provide the HBV DNA assay with a detection limit of 300 IU/ml, whose reaction time was approximately 67 mins rather than the 108 mins performed by the comparator. During the establishment of the standard curve, this fast PCR test shows a strong linear correlation (R2 = 0.9919) between targeted gene concentration and dilution factor. Additionally, among the 200 clinical samples, we used the microchip-based system to rapidly complete quantitative detection for each sample with high sensitivity of 100% (100/100) and specificity of 100% (100/100), which is critically consistent with the traditional PCR method. Conclusion Hence, the point-of-care microfluidic PCR system exhibits great feasibility in offering timely, accurate, and reliable molecular diagnosis for early epidemic disease screening and therapeutic guidance of chronic infections.

Shifts in bacterioplankton community structure between dry and wet seasons in a tropical estuary strongly affected by riverine discharge

Estuaries are among the most productive ecosystems in the world and are highly dynamic due to the interaction of freshwater and seawater, which results in strong spatial gradients in physico-chemical conditions. Bacterioplankton play a central role in these systems, driving the fluxes of carbon and energy, and being central for contaminant removal in human-impacted areas. Most studies on bacterioplankton dynamics have been carried out in temperate estuaries, and they show that salinity is a major factor driving bacterioplankton distribution. Tropical estuaries, although largely understudied, experience drastic variations in river discharge between the dry and the rainy seasons, influencing the spatial distribution of the salinity gradient and thus likely impacting bacterioplankton communities. Using Illumina sequencing of the 16S rRNA gene, here we studied bacterial communities from the Nicoya's Gulf (Costa Rica), a large tropical estuary characterized by high riverine discharge during the rainy season, to explore seasonal changes in the spatial distribution and connectivity of these communities along the Gulf. Our results show pronounced differences in bacterial diversity and community structure between seasons and zones within the estuary (the shallow upper Gulf, the middle zone and the lower zone, located in the marine end of the estuary). Bacterial communities from the different regions were more similar during the rainy season, suggesting a larger degree of microbial connectivity likely driven by the fast water circulation fueled by the riverine discharge. In the dry season, Enterobacteriales and Cyanobacteria dominated bacterial communities, whereas in the rainy season Alphaproteobacteria was the dominant group. These contrasting seasonal trends were consistent with the seasonal variations observed in bacterial assemblages during a year at a single station in the upper region of the Gulf. We conclude that the Gulf is highly dynamic in both the spatial and temporal scale and that bacterioplankton communities are strongly influenced by the riverine and tidal inputs during both seasons. This study sheds light on the sources of variability in the structure of bacterial communities in tropical estuarine systems, an understudied type of aquatic ecosystem, and sets the basis to design further comprehensive studies on their microbial diversity.

Gap opening in protoplanetary discs: gas dynamics from global axisymmetric non-ideal MHD simulations with consistent thermochemistry

ABSTRACT Recent high angular resolution ALMA observations have revealed numerous gaps in protoplanetary discs. A popular interpretation has been that planets open them. Most previous investigations of planet gap-opening have concentrated on viscous discs. Here, we carry out 2D (axisymmetric) global simulations of gap opening by a planet in a wind-launching non-ideal MHD disc with consistent thermochemistry. We find a strong concentration of poloidal magnetic flux in the planet-opened gap, where the gas dynamics are magnetically dominated. The magnetic field also drives a fast (nearly sonic) meridional gas circulation in the denser disc regions near the inner and outer edges of the gap, which may be observable through high-resolution molecular line observations. The gap is more ionized than its denser surrounding regions, with a better magnetic field–matter coupling. In particular, it has a much higher abundance of molecular ion HCO+, consistent with ALMA observations of the well-studied AS 209 protoplanetary disc that has prominent gaps and fast meridional motions reaching the local sound speed. Finally, we provide fitting formulae for the ambipolar and Ohmic diffusivities as a function of the disc local density, which can be used for future 3D simulations of planet gap-opening in non-ideal MHD discs where thermochemistry is too computationally expensive to evolve self-consistently with the magneto-hydrodynamics.

Research on the influence of check valve on noise performance of variable frequency scroll refrigeration compressor

Check valve is one of the core components of the scroll refrigeration compressor, which can directly affect its efficiency, life, and noise performance. Traditional check valve is the reed valve. This paper deeply studies the dynamic characteristics of reed valve and reveals the main reason of the valve noise under different rotation speeds. The large noise is mainly attributing to the large pressure pulsation as well as fast circulation velocity of fluid and the severe slapping of the reed plate on the valve seat, which is influenced by the high pressure ratio of the working condition and stiffness of the reed valve. In order to reduce the noise of the check valve, the circular valve is designed to replace reed valve in this paper. At each rotation speed, the circular valve shows a continuous exhaust process, which avoids the slapping of the valve plate on the valve seat. More importantly, the exhaust is smooth and the pressure pulsation as well as the flow rate of the fluid is reduced significantly leading to the low aerodynamic noise. Therefore, compared with the reed valve compressor, the sound pressure level of the circular valve compressor at 1800, 4200, and 6600 rpm is decreased by 3.0, 5.2, and 0.3 dB, respectively.

The overlooked role of electrostatic repulsion between nanoparticle catalysts in ligand-enhanced heterogeneous Fenton-like reactions

Chelating agents are now frequently used to facilitate Fenton and Fenton-like reactions by building complexes with iron. A series of advantages can be exemplified, such as fast circulation of Fe(Ⅲ)/Fe(Ⅱ), enhanced catalytic performance of Fe-ligand, and iron precipitation inhibition, etc. However, few studies explored whether electrostatic repulsion between nanoparticle catalysts had an influence on catalytic performance in ligand-enhanced Fenton-like reactions. In this study, we discovered that the coexistence of 0.1 mM EDTA and 10 mM phosphate dramatically accelerated diclofenac (DCF) degradation by Fe3O4/Air (∼95% within 20 h). In-depth explorations demonstrated the enhanced electrostatic repulsion between Fe3O4 caused by the addition of EDTA and phosphate played a key role in the promoted DCF degradation. The enhanced electrostatic repulsion between Fe3O4 led to a notable increase in the percentage of Fe-EDTA, which benefited O2 activation and DCF degradation. Reactive oxygen species (ROS) were mainly generated through one-electron activation mechanism of O2 and •OH were confirmed to be predominant active species responsible for DCF degradation. Fe(Ⅱ)-EDTA on Fe3O4 surface was evidenced to be served as main sites for O2 and H2O2 activation. During the degradation reaction, sufficient surface Fe(Ⅱ) on Fe3O4 was maintained with the assistance of EDTA. Toxicity analysis showed that DCF was transformed into less toxic intermediates, demonstrating the feasibility of this technology in practical applications. This work for the first time reveals the importance of electrostatic repulsion between nanoparticle catalysts in ligand-enhanced Fenton-like reactions, providing a low-cost and effective advanced oxidation process for contaminants degradation.

The current situation of fast fashion industry and how to reduce the waste

Since entering the 21st century, the development of fast fashion has faced a number of environmental problems. The design of circular economy is the best way to deal with fast fashion pollution, while the existing recycling system, traditional waste disposal methods are inefficiencies and are no longer enough to deal with the pollution caused by today's fast fashion industry. So this paper discusses some cutting-edge technologies to meet the development of circular fashion and achieve the approaches for sustainable development of fashion industry. After a specific analysis of the pollution of the fast fashion industry to the climate, water and the waste caused, this paper introduces the infrared technology to accelerate the sorting of clothing raw materials in the waste, enzymatic technology to process and degrade the raw materials, and the use of new sustainable materials in three steps to obtain an advanced technology support, sustainable fashion circulation system. In the future, this improved fast fashion circulation system still needs more experiments to be tested, also the government and relevant departments need to formulate relevant policies to support the development of this system. On the other side, the fast fashion industry's pollution of the environment, especially water bodies, and its treatment methods need to be studied.

Digitalisasi Manajemen Sistem Dokumen Pengelolaan Perpustakaan Universitas Bumigora Menggunakan Teknologi Radio Frequency Identification (RFID)

Bumigora University developed a web-based library information and data processing system, while the contents of the development of the system were only limited to a single information system in which only admin operators handled the system without any direct interaction with library users, while in the analysis and development of the library system only limited to acquisition and return transactions with a system without involving library human resources, but there are problems that are still often encountered in the management of a library at Bumigora University, there is no guarantee of book safety in the library and the work system of library human resources is not yet optimal. Based on this, a Wireless RFID (Radio Frequency Identification) Technology device is needed. This technology supports the identification of book library reshelving, book libraries, book returns with self-service which is expected to provide more accurate information, improve future library services in addition to complementing security aspects. The purpose of this study is to describe the opportunities for Wireless RFID (Radio Frequency Identification) technology to be applied in the Bumigora University library. This study uses an explanatory theory that must be built by researchers based on general data in observations that must be analyzed, explained and interpreted, and uses qualitative methods. The results show that the use of RFID technology in libraries applies both to university libraries, regional libraries, school libraries and others. The use of RFID by Higher Education Libraries will greatly support the following: a. High Speed ​​Inventory System b. Fast Circulation Process The use of RFID will speed up a borrowing and returning circulation process. Therefore, the application of Wireless RFID (Radio Frequency Identification) Technology in the Bumigora University library is needed to create a safe and professional library management.

Application of intense pulsed light – plasma – ultraviolet combined system on granular and powdered foods for microbial inactivation

The bactericidal effects of a self-designed device that combines intense pulsed light (IPL), plasma, and ultraviolet irradiation (UV) on granular and powdered foods, and the changes induced in the properties of the samples were studied. Samples were treated by combined IPL-plasma-UV system continuously. A maximum 1.33 ± 0.24-log reduction of microorganisms on sesame seeds were achieved using the combined system, while maximum 1.12 ± 0.18- and 0.59 ± 0.06-reductions were achieved using IPL-only and plasma-only systems, respectively. Using the combined system achieved maximum 0.41 ± 0.04- and 0.51 ± 0.05-log reductions of microorganisms on black pepper powder and red pepper powder, respectively, which have more holes, cracks, and crevices than sesame seeds. Significant changes in water activity, moisture content, and color were found in all samples due to drying caused by fast circulation or plasma treatment. So further research is needed to reduce the changes of the sample properties after the combined system.

Merging Multiphase CTA Images and Training Them Simultaneously with a Deep Learning Algorithm Could Improve the Efficacy of AI Models for Lateral Circulation Assessment in Ischemic Stroke

We aimed to build a deep learning-based, objective, fast, and accurate collateral circulation assessment model. We included 92 patients who had suffered acute ischemic stroke (AIS) with large vessel occlusion in the anterior circulation in this study, following their admission to our hospital from June 2020 to August 2021. We analyzed their baseline whole-brain four-dimensional computed tomography angiography (4D-CTA)/CT perfusion. The images of the arterial, arteriovenous, venous, and late venous phases were extracted from 4D-CTA according to the perfusion time–density curve. The subtraction images of each phase were created by subtracting the non-contrast CT. Each patient was marked as having good or poor collateral circulation. Based on the ResNet34 classification network, we developed a single-image input and a multi-image input network for binary classification of collateral circulation. The training and test sets included 65 and 27 patients, respectively, and Monte Carlo cross-validation was employed for five iterations. The network performance was evaluated based on its precision, accuracy, recall, F1-score, and AUC. All the five performance indicators of the single-image input model were higher than those of the other model. The single-image input processing network, combining multiphase CTA images, can better classify AIS collateral circulation. This automated collateral assessment tool could help to streamline clinical workflows, and screen patients for reperfusion therapy.

Active Circulating Blood Volume During Hemodialysis: A Bench Model.

Intradialytic hypotension due to excessive fluid removal is a common complication of hemodialysis. A bench model was constructed to evaluate quantification of active circulating blood volume (ACBV). The model included a central pump representing the heart and compartments to represent the central and peripheral circulation. A blood oxygenator was used to simulate lung volume and two containers represented fast and slow circulation compartments. A separate dialysis circuit with a blood pump and two ultrasound flow-dilution probes was incorporated. Vascular access was simulated with both a shunt (fistula or graft) and a central venous catheter. Hypertonic saline (5%) was circulated in the system. A bolus of isotonic saline was introduced in the dialysis circuit, which dispersed through the physiologic model. ACBV was measured by comparing the baseline dilution curve to the curve as it returned to the probes. To evaluate the sensitivity of this technique, we investigated changing cardiac output, central venous volume, shunt flow, vascular access type, and HD pump flow. Overall percentage error (mean ± SD) across all tests (n = 15 conditions, each in triplicate) was 2.6% ± 7.4%. This study demonstrates the ability to accurately measure ACBV on the bench.

The evolution, benefits, and challenges of preprints and their interaction with journals

This article presents the growth and development of preprints to help authors, editors, and publishers understand and adopt appropriate strategies for incorporating preprints within their scholarly communication strategies. The article considers: preprint history and evolution, integration of preprints and journals, and the benefits and disadvantages, and challenges that preprints offer. The article discusses the two largest and most established preprint servers, arXiv.org (established in 1991) and SSRN (1994), the OSF (Open Science Foundation) initiative that supported preprint growth (2010), bioRxiv (2013), and medRxiv (2019). It then discusses six different levels of acceptance of preprints within journals: uneasy relationship, acceptance of preprint articles, encouraging authors to preprint their articles, active participation with preprints, submerger by reviewing preprints, and finally merger and overlay models. It is notable that most journals now accept submissions that have been posted as preprints. The benefits of preprints include fast circulation, priority publication, increased visibility, community feedback, and contribution to open science. Disadvantages include information overload, inadequate quality assurance, citation dilution, information manipulation and inflation of results. As preprints become mainstream it is likely that they will benefit authors but disadvantage publishers and journals. Authors are encouraged to preprint their own articles but to be cautious about using preprints as the basis for their own research. Editors are encouraged to develop preprint policies and be aware that double-blind review is not possible with preprinting of articles and that allowing citations to preprints is to be encouraged. In conclusion, journal-related stakeholders should consider preprints as an unavoidable development, taking into consideration both the benefits and disadvantages.

Mechanisms of Fast Walker Circulation Responses to CO2 Forcing

AbstractThe Walker circulation (WC) responds to CO2 forcing at both short and long timescales. In climate models, the fast response accounts for a substantial portion of the total responses, but its mechanisms, particularly those pertaining to air‐sea interactions, remain unclear. We find contrasting fast WC responses in the first 2 years of abrupt CO2 forcing, determined by the models' air‐sea coupling strength in the equatorial Pacific. In models with a strong coupling, wind anomalies induced by the instantaneous land‐sea thermal contrast trigger a Bjerknes feedback, leading to cooling in the equatorial Pacific and WC strengthening. The WC weakens gradually as the Bjerknes feedback wanes and the subsurface warm pool water migrates eastward as Kelvin waves. In models with a weaker coupling, the WC weakens monotonically. Our results suggest that the inter‐model discrepancy in WC changes is associated with the uncertainty in the fast component.

Climate and ice sheet evolutions from the last glacial maximum to the pre-industrial period with an ice-sheet–climate coupled model

Abstract. The last deglaciation offers an unique opportunity to understand the climate–ice-sheet interactions in a global warming context. In this paper, to tackle this question, we use an Earth system model of intermediate complexity coupled to an ice sheet model covering the Northern Hemisphere to simulate the last deglaciation and the Holocene (26–0 ka). We use a synchronous coupling every year between the ice sheet and the rest of the climate system and we ensure a closed water cycle considering the release of freshwater flux to the ocean due to ice sheet melting. Our reference experiment displays a gradual warming in response to the forcings, with no abrupt changes. In this case, while the amplitude of the freshwater flux to the ocean induced by ice sheet retreat is realistic, it is sufficient to shut down the Atlantic meridional overturning circulation from which the model does not recover within the time period simulated. However, with reduced freshwater flux we are nonetheless able to obtain different oceanic circulation evolutions, including some abrupt transitions between shut-down and active circulation states in the course of the deglaciation. The inclusion of a parameterisation for the sinking of brines around Antarctica also produces an abrupt recovery of the Atlantic meridional overturning circulation, absent in the reference experiment. The fast oceanic circulation recoveries lead to abrupt warming phases in Greenland. Our simulated ice sheet geometry evolution is in overall good agreement with available global reconstructions, even though the abrupt sea level rise at 14.6 ka is underestimated, possibly because the climate model underestimates the millennial-scale temperature variability. In the course of the deglaciation, large-scale grounding line instabilities are simulated both for the Eurasian and North American ice sheets. The first instability occurs in the Barents–Kara seas for the Eurasian ice sheet at 14.5 ka. A second grounding line instability occurs ca. 12 ka in the proglacial lake that formed at the southern margin of the North American ice sheet. With additional asynchronously coupled experiments, we assess the sensitivity of our results to different ice sheet model choices related to surface and sub-shelf mass balance, ice deformation and grounding line representation. While the ice sheet evolutions differ within this ensemble, the global climate trajectory is only weakly affected by these choices. In our experiments, only the abrupt shifts in the oceanic circulation due to freshwater fluxes are able to produce some millennial-scale variability since no self-generating abrupt transitions are simulated without these fluxes.

A shortcut to carbon-neutral bioplastic production: Recent advances in microbial production of polyhydroxyalkanoates from C1 resources

Since the 20th century, plastics that are widely being used in general life and industries are causing enormous plastic waste problems since improperly discarded plastics barely degrade and decompose. Thus, the demand for polyhydroxyalkanoates (PHAs), biodegradable polymers with material properties similar to conventional petroleum-based plastics, has been increased so far. The microbial production of PHAs is an environment-friendly solution for the current plastic crisis, however, the carbon sources for the microbial PHA production is a crucial factor to be considered in terms of carbon-neutrality. One‑carbon (C1) resources, such as methane, carbon monoxide, and carbon dioxide, are greenhouse gases and are abundantly found in nature and industry. C1 resources as the carbon sources for PHA production have a completely closed carbon loop with much advances; i) fast carbon circulation with direct bioconversion process and ii) simple fermentation procedure without sterilization as non-preferable nutrients. This review discusses the biosynthesis of PHAs based on C1 resource utilization by wild-type and metabolically engineered microbial host strains via biorefinery processes.