Trading animals between farms and via markets can provide a conduit for spread of infections. By studying trading networks, we might better understand the dynamics of livestock diseases. We constructed ingoing contact chains of cattle farms in Great Britain that were linked by trading, to elucidate potential pathways for the transmission of infection and to evaluate their effect on the risk of a farm experiencing a bovine tuberculosis (bTB) incident. Our findings are consistent with variation in bTB risk associated with region, herd size, disease risk area and history of previous bTB incidents on the root farm and nearby farms. However, we also identified effects of both direct and indirect trading patterns, such that connections to more farms in the England High-Risk Area up to three movements away from the root farm increased the odds of a bTB incident, while connections with more farms in the England Low-Risk Area up to eight movements away decreased the odds. Relative to other risk factors for bTB, trading behaviours are arguably more amenable to change, and consideration of risks associated with indirect trading, as well direct trading, might therefore offer an additional approach to bTB control in Great Britain. These pathways exist at many scales, describing transmission among individuals , farms  and counMycobacterium bovis causes bovine tuberculosis (bTB) in cattle but can infect a wide range of mammalian species [Meles meles, and undetected infections and movements of cattle have been shown to contribute to disease persistence and spread. A dynamic transmission model using British cattle movement and bTB testing data from 1996 to 2011 predicted that the movements of cattle alone accounted for 13% of bTB incidents and played a further role in multifactorial bTB incidents [et al. [ species . Despite species . Among o [et al.  suggeste [et al.  and over [et al. . However [et al. –17, studWhen compared to other risk factors for bTB incidents, such as location and herd type, cattle movements represent an activity that might be more amenable to management, for example, by the use of risk-based trading, regulation or legislation. While the role of direct cattle movements in the transmission of bTB in Great Britain has been well-documented, the risks associated with indirect movements arising from trade have not yet been quantified or explored in detail. Second-order contacts (i.e. contacts of contacts) in farm networks have been shown to improve the estimates of simulated epidemic size in models of disease in the British cattle herd  and, in We have previously constructed contact chains for all cattle herds in Great Britain and found that a large proportion of herds have remarkably extensive chains, extending to tens of thousands of other farms within 12-month periods . In the 2.2.1.M. bovis, using either of the statutory live tests: the single intradermal cervical comparative tuberculin (SICCT) test or the gamma interferon test, and is withdrawn (OTF-W) upon finding post-mortem pathology characteristic of M. bovis or isolation of the bacteria by culture. Both types of incident were included in the analysis in order to maximize the power of tests of the association between infection in the contact chain and subsequent incidents. Two additional analyses were performed with each type of incident as the response variable (OTF-S and OTF-W), but final outcomes did not change substantially and so the simpler, combined analysis is presented here.We obtained bTB surveillance and farm information data collated in the Cattle Tracing System (CTS) by the Animal and Plant Health Agency (APHA). Study farms were active premises  between 1 January 2012 and 31 December 2014 with full bTB testing and location data, resulting in a final dataset comprising 71 096 cattle farms. Annual herd size was derived from the mean daily number of cattle on the premises. We took the mean of these annual herd sizes across the three years of the study. Herd type was defined using CTS data, first by the predominant breed type  and then sex of animals on the farm  within the study period is included in the chain as a ‘source farm'. The ‘level' for each source farm corresponds to the minimum number of movements away from the root farm at which they appear in the ingoing contact chain. To avoid any seasonal effect of starting the chain in a specific month, we calculated 24 ICCs at one month intervals, each spanning 12 months of movements. We then grouped the source farms from each of the 24 ICCs. Where farms appeared more than once in the chain in any one year, we included them at the closest (minimum) level to the root farm and removed other instances. Each chain was curtailed at eight levels away from the root farm due to computational limitations .A single-directed network was calculated for each of the three study years, representing farms as nodes and with farm-to-farm movements of at least one animal represented by edges, weighted by the number of animals traded between those farms in the study year . Betweenness centrality was calculated for each root farm in each network, providing a centrality measure of the importance of the farm in connecting together different parts of the network . ICCs arFor each root farm, we quantified how many source farms from each region were at each level of the contact chain and how many source farms at each level experienced a bTB incident from 2010 to 2014. We used cumulative counts across the different levels, e.g. the number of source farms at level one, the sum of the number of source farms at levels one and two, etc., up to the eighth level. We recorded the mean distance between each root farm and all of their source farms at each level. To incorporate bTB risks from local farms, we calculated the proportion of farms that had experienced a bTB incident between 2010–2014, within a radius of 0–2 km, 0–4 km, 0–6 km, 0–8 km and 0–10 km of the root farm. Location was defined by the  coordinates associated with a particular holding identity (County Parish Holding number) in the APHA data. There are limitations with this proxy for farm location because, in some cases, the point location of the CPH does not lie within farmland where cattle are mostly located. However, there is no known systematic spatial bias to these locations, sample size is very large and there are no validated alternatives at this scale. Thus, this is the best proxy to use, and it has been used in previous studies ,18. We sWe specified a multivariable regression model using a baseline set of variables  with thestandardized ORs , which would not be sensible here due to high asymmetry in the distributions of some of the explanatory variables). Model performance was assessed  and we tested for overfitting of the final model using bootstrapping [To aid comparison of odds ratios (ORs) between variables specified on different scales, we re-scaled the coefficients for continuous variables such that each estimate corresponds to the OR for a variable changing from the 10th percentile to the 90th percentile of the observed data . An average root farm in the England Edge Area, England Low-Risk Area or in Wales had about 20–25% of its source farms located in the England High-Risk Area . Also, 2In 2015–2016, 12.9% of root farms experienced a bTB incident, of which 78.5% were classified as OTF-W . Proportions of bTB incidents classified as OTF-W or OTF-S in the England High-Risk Area and Wales mirrored those in Great Britain as a whole, whereas in the England Edge Area the relative proportions of these classifications were more equal and in the England Low-Risk Area and Scotland, there were more bTB incidents classed as OTF-S than OTF-W . Characteristics of the root farm and local bTB history were major risk factors associated with the likelihood of a bTB incident. Compared to farms in Scotland and the England Low-Risk Area, root farms located in the England Edge Area or England High-Risk Area, or in Wales, had greater odds of experiencing a bTB incident in 2015–2016 . Root faIn selecting our variables, model performance was better (i.e. a lower AIC) when we included the number of source farms in the England High-Risk Area, than those in the England Edge Area, Wales or the number of source farms with a bTB incident in the last 5 years . A root farm with more farms in the England High-Risk Area at levels 1–3 of their ICC had 1.11 (1.07–1.15) times higher odds of having a bTB incident . We founOur regional analyses showed broadly similar effect sizes to those obtained using the entire Great Britain dataset; however, there were key differences in the effect sizes for bTB history on root farms and neighbouring farms . While we found a modest effect (OR = 1.23) of having made a direct purchase from the England High-Risk Area, our results suggest that there is scope for further reductions in the risks of acquiring bTB through trading links. For herds with non-negligible levels of infection, the SICCT test has reasonable sensitivity when considered as a herd-level test [Our study covers the period 2010–2016, 4 to 10 years after the introduction of comprehensive pre-movement testing, and selective post-movement testing, and indicates that there remains an increased risk of bTB incidents associated with direct vel test ; howevervel test , resultivel test  and pre-vel test , we showvel test . The usevel test  in movemvel test , and incvel test . Clearlyvel test . Focussivel test . Therefoet al. [Results of the present study show that having more farms in the ICC was initially associated with increased risk, as observed in a similar study of cattle contact chains in France . Howeveret al. . Howeveret al. .Spatial proximity to farms with recent bTB incidents increased the risk of a bTB incident on the root farm in the full Great Britain model and regional models except for Scotland. We expected that farms closest (i.e. 0–2 km) to the root farm would have the greatest effect on this risk as this would encompass potential contacts of cattle on shared boundaries and the risks from infected local wildlife . Howevern = 21) and the England Low-Risk Area (n = 60) and broad confidence intervals of this variable, the effect of previous incidents in the preceding 5 years (2010–2014) on the risk of a later incident in Scotland or in the England Low-Risk Area was considerably greater than the effect of prior history in the higher risk areas of England and Wales. As the environmental force of re-infection in non-endemic areas is likely to be low, this suggests that a small number of herds in Scotland and the England Low-Risk Area may have had OTF status restored without having fully eliminated infection [Notwithstanding the low number of repeat bTB incidents in Scotland (nfection , or altenfection , where bAn advantage of the regression framework employed in the present study is that it is more straightforward to fit these models to complex data than it would be to fit a fully mechanistic infectious disease model ,41. HoweThe effects of trading patterns in our study were relatively small compared to other known risk factors such as herd size ,44 and pFurther methodological information, figures and tables supporting this article have been uploaded as part of the electronic supplementary material.


Supercapacitors are energy storage devices with high power density, rapid charge/discharge rate, and excellent cycle stability. Carbon-based supercapacitors are increasingly attracting attention because of their large surface area and high porosity. Carbon-based materials research has been recently centered on biomass-based materials due to the rising need to maintain a sustainable environment. Cellulose and lignin constitute the major components of lignocellulose biomass. Since they are renewable, sustainable, and readily accessible, lignin and cellulose-based supercapacitors are economically viable and environmentally friendly. This review aims to systematically analyze published research findings on electrospun lignin, cellulose, and lignin/cellulose nanofibers for use as supercapacitor electrode materials. A rigorous scientific approach was employed to screen the eligibility of relevant articles to be included in this study. The research questions and the inclusion criteria were clearly defined. The included articles were used to draw up the research framework and develop coherent taxonomy of literature. Taxonomy of research literature generated from the included articles was classified into review papers, electrospun lignin, cellulose, and lignin/cellulose nanofibers for use as supercapacitor electrode materials. Furthermore, challenges, recommendations, and research directions for future studies were equally discussed extensively. Before this study, no review on electrospun lignin/cellulose nanofiber-based supercapacitors has been reported. Thus, this systematic review will provide a reference for other researchers interested in developing biomass-based supercapacitors as an alternative to conventional supercapacitors based on petroleum products. Thus, a green approach to an effective energy production system that can replace fossil fuels is necessary [Human activities, security, and industrialization depend on energy production and this energy is mostly derived from fossil fuels . Howeverecessary ,4. Recenecessary . Due to ecessary . Howeverecessary . It is tBiomass cellulose , being the most abundant biological macromolecules in nature, is a good precursor material for electrospinning CNFs due to its good flexibility and essential properties . In the The study into CNFs made from a lignin/cellulose blend is a new research field that needs to be explored due to the rising need for energy storage devices based on biomass CNFs. As far as we know, only a few papers on electrospun lignin/cellulose nanofibers for energy storage have been published. Interestingly, the few studies show that supercapacitors based on lignin/cellulose may be an exotic area of research interest in the field of supercapacitors based on carbon biomass precursors. Besides, both lignin and cellulose are green and sustainable, and their extraction methods are very simple, economical, and eco-friendly. The need to investigate this new field is, therefore, very evident. Many reviews on electrospun lignin and cellulose nanofibers have been published. However, very few systemic reports are available on both lignin and cellulose nanofibers. In particular, no review of electrospun nanofibers from a blend of these abundant biomass materials has been published. This study is a systematic review of all the literature  published on the electrospun lignin, cellulose, and lignin/cellulose nanofibers for supercapacitor application between 2010 and 2020. The study reviewed related papers systematically, discussed the advancement of research on the topic, defined areas of research gap, made suggestions, and presented research directions for future studies on the field of carbon-based supercapacitor electrodes. To create a sound base for our study, this systematic review reports on electrospun lignin and cellulose nanofibers independently followed by electrospun lignin/cellulose nanofibers. The papers used in this study are only restricted to supercapacitors application involving lignin and cellulose nanofibers. Thus, this systematic review is likely to inspire researchers working in this field to focus more on biomass-based CNFs as an ideal alternative to petroleum-based CNFs as supercapacitor electrode materials.On a general note, a literature review helps to identify and bridge research gaps in a particular research area. A systematic review of literature is quite different from the general review because its protocol is well defined, scientific, and rigorous. The scientific approach employed in systematic review ensures rigorous identification of the research area, summarizes the state of the art research progress, identifies research gaps, and suggests directions for further research . Thus, aWith the growing demand for low-cost and high-performance energy storage systems, biomass lignin and cellulose are the preferred materials for future supercapacitors due to their natural abundance, thermal and chemical stability, low cost, durability, and large surface area. As the market for energy storage devices derived from renewable materials continues to grow, many researchers have dedicated themselves to biomass-derived materials because of their economic and environmental advantages. For this reason, cellulose and lignin are the most suitable precursors for biomass-based supercapacitors. Supercapacitors fabricated from electrospun lignin, cellulose, and a blend of lignin and cellulose are discussed as emerging research trends in carbonaceous materials for EDLC application. Thus, the principal purpose of this systematic review is to analyze the state-of-the-art studies on electrospun lignin/cellulose nanofibers for use in supercapacitors. Two research questions are formulated to guide this research in achieving the stated goals.RQ1: What are the physiochemical properties of electrospun lignin and cellulose nanofibers reported by researchers and what are the electrochemical performance of the fabricated supercapacitors? RQ2: How successful are nanofibers derived from electrospun lignin and cellulose blend when used as supercapacitor electrode materials?The stated research questions will assist in analyzing the research progress on electrospun lignin and cellulose nanofibers as electrode materials for supercapacitors. Since lignin and cellulose are cheap, nontoxic, and readily available, electrospinning of lignin/cellulose precursor into nanofibers with optimized performance could be the next generation supercapacitor material.Search strategy for articles relevant to the scope of the research was done in three stages: (1) selecting databases and other sources of data, (2) identifying the keywords to search on databases, and (3) defining the search process used to obtain relevant documents.Three databases were used as sources of research articles for this study: Web of Science, Scopus, and ScienceDirect. These databases are among the most inclusive scientific databases which provide extensive peer review research literature in the field of science. They provide search tools that can be effectively used to obtain bibliographic information as well as research articles. To obtain relevant articles, different keywords were used to search databases. The authors noticed that the selected keywords are the most common keywords used in relevant articles. Advanced search by title was done on each database. To enrich our information, a query search was done using different combinations of the keywords as presented in Query search was performed for all relevant articles on 11 September 2020. Each query search was performed three times to ensure consistency in the query output. After every query search at different instances, all databases resulted in a fixed number of articles for each keyword except when keywords were changed. For example, step 7 was delimitated as TI = (“electrospinning” AND “nanofiber” AND “lignin”) and TITLE (“electrospinning” AND “nanofiber” AND “lignin”) AND PUBYEAR > 2008 AND PUBYEAR < 2021 on Web of Science and Scopus databases, respectively. The final query search resulted in 11,450 relevant articles from all the databases used . Relevant articles used for this systematic review include original research journals, review papers, conference proceedings, and book chapters.A lot of comprehensive work  on electrospun cellulose and lignin nanofibers have been published. However, our established goals restrict our work to electrospun lignin and cellulose nanofibers for use in supercapacitors only. Therefore, our targeted research articles are those that meet our selection criteria only. From our query search, no literature relevant to the scope of this study was published before 2010. Hence, all articles published before 2010 were not included in the review. Furthermore, the only peer-reviewed articles published in the English language are used for this systematic review. Other criteria—such as journal ranking, publishing country, article access type, etc.—were not included in our selection criteria. Criteria for including articles in this systematic review are similar to those reported in a previous study . The incAll articles that do not meet the above inclusion criteria were excluded. Articles with no clear contribution to the scope of this systematic review were also excluded during the screening process.Screening of relevant articles to be included in this systematic review follows the PRISMA  framework . As prevIn a systematic review, a final search was done to obtain articles with the most relevant information. As stated earlier, 11,450 references were initially imported to EndNote from databases. Authors equally included 39 articles from other sources. Using EndNote reference manager, 6088 duplicates were detected and removed. However, in the course of manual screening, 106 additional duplicates were further removed. Eligibility and screening processes were done in three stages to obtain articles that strictly fall within the objectives of this study and met the inclusion criteria. The first screening was done by simply reading the titles of the articles. By so doing, 5098 articles were screened out resulting in 197 articles left. These are articles that reported on either; electrospun lignin and cellulose nanofibers for other applications  or lignin and cellulose nanofibers for supercapacitor applications prepared via other methods .To further scrutinize our remaining literature, a second screening was performed by reading the abstracts of the articles that passed the first screening. Out of 197 articles, 14 articles were screened out because we could not obtain the full articles. Also, 55 book chapters with no significant information were screened out. At the end of this screening, 128 articles were obtained. The final screening was performed by scanning through the entire articles remaining, to further determine their relevance to the scope of this study. The authors observed that 70 articles have no clear contributions to offer to the research topic and were therefore screened out. Most of these articles were conference papers that did not express a concise methodology or did not present a sufficient explanation of results to answer our research questions. Many biases are likely to arise when looking for the right research for writing the systematic review. Bias involving arbitrary search constraints such as geographic locations, search items, electronic databases, publishing languages or publication period may be included by the review authors. Bias is a methodological mistake in research, leading to the adoption of findings and conclusions without taking adequate account of the probability of inaccurate or misleading reports. Publication bias exists where the findings of published research vary from the results of unpublished studies. We may assess publication bias by comparing the findings of published and unpublished research addressing the same research question ,21.Bias analyses are relevant because they allow the authors and the readers to assess how accurate and reliable the data included in the study are. For this study, publication bias was not estimated because authors were neither able to get unpublished research work on the topic nor published articles with negative/irrelevant results which would be compared with the published research work with positive outcomes. At the end of the screening of the included articles for eligibility, a total of 58 relevant articles with a clear contribution to the study were eventually collected for the systematic review at the end of the eligibility and screening process. These articles were further studied extensively to establish a full framework of literature taxonomy and to map out our research. The development of a taxonomy of literature from our included articles was based on three categories of literature: articles on electrospun lignin nanofibers, articles on cellulose nanofibers, and articles on electrospun lignin/cellulose nanofibers. The distribution of articles used in the literature taxonomy is shown in While research into supercapacitors based on lignin/cellulose is currently at its early stage, it is important to review this new field of study to improve the research community’s awareness of the subject. It is expected that this review will help to divert the attention of researchers from petroleum-derived carbonaceous electrode materials such as PAN, rayon, and pitch to renewable and sustainable biomass-based electrodes. If explored, this field of study will offer sufficient opportunity to study lignocellulose-based electrode materials. The evolution of research articles included in this study per years of publication is presented in Comparatively, the distribution of research articles used in this study according to countries of authors is shown in Several review articles on electrospun lignin and cellulose nanofibers were published over the years. For this study, these reviews are divided into three categories: (1) reviews on electrospun cellulose nanofibers for supercapacitors, (2) reviews on electrospun lignin nanofibers for supercapacitors, and (3) reviews on biomass-derived nanofibers for supercapacitors. In this regard, only the review papers that are highly relevant to our study and fulfil our inclusion criteria have been selected. After the examination of the available review publications, 11 review papers  with clear relevance to our goals were included in this systematic review. The number of the review articles classified according to their categories  of the total relevant articles used in this study to create literature taxonomy to develop the research framework. The distribution of the included experimental research articles based on electrode active materials  are shown in Out of the 47 articles, 21 reported on electrospun cellulose nanofibers, 34 reported on electrospun lignin nanofibers and 8 reported on electrospun lignin/cellulose nanofibers. For electrospun lignin nanofibers, 23 out of 34 reported on various polymeric binders blended with lignin to successfully electrospin lignin precursor into nanofibers. Based on the included literature, this section discusses the research progress in the field of supercapacitors derived from electrospun lignin and cellulose nanofibers over the years (2010–2020) based on Web of Science, Scopus, and Science Direct electronic databases.Cellulose is the most abundant natural macromolecule and the main ingredient of lignocellulose biomass. It has a high carbon content of around 44%, high stability, and outstanding porosity due to its hierarchical composition and highly functional rigid linear chains ,23. Cell2 content in the precursor solution. Ths reveals that ZnCl2 increases thermal and structural stability by efficient ion interlinking of CA macromolecules, thus promoting dehydrogenation.In CNF formation, the selection of an appropriate solvent is extremely significant. The right solvent that can evaporate quickly during the electrospinning process is required to facilitate jet elongation leading to nanofiber formation. Cellulose electrospinning solution is difficult to prepare because it is normally not soluble in most organic solvents. However, cellulose acetate (CA) is much easier to electrospin because the solubility of CA depends on the degree to which acetate group is replaced. Therefore, CA is the most widely used cellulose derivative to prepare cellulose nanofibers. According to one report, CA was dissolved in acetone and dimethyl acetamide (DMAc) to electrospin CA nanofibers followed by hydrolysis in NaOH/ethanol solution at room temperature for 12 h prior to thermal treatment . These nIn another study by Y. Lie et al. , CA (in Ethyl cellulose (EC) is another cellulose derivative used to electrospin cellulose nanofibers. EC electrospinning precursor solution was prepared by dissolving EC in a mixture of dimethyl formamide (DMF) and acetone . PrepareThe interaction between solvent and polymer  is another factor that significantly affects polymer chains which are responsible for nanofiber formation. CA precursor solution was prepared using dichloromethane (DMC)/ethanol and DMF/ethanol at different concentrations . At a hi2 nanoparticles into cellulose acetate spinning solution in acetone/DMAc to prepare cellulose electrospinning solution. Although the addition of SiO2 reduced fiber diameter, spinnability of the precursor solution was not affected. SiO2 has been shown by other researchers to improve electrical properties by improving the porosity of prepared CNFs but not the solubility or spinnability of the precursor solutions [2 nanoparticles effectively controlled the thermal stability of prepared nanofibers.M. S. Nasir et al.  incorporolutions ,32,33. RThe method for electrode materials synthesis plays a crucial role in the regulation of substrate structures and characteristics , control variables , and environmental parameters  ,39. WhenCellulose is insoluble in most organic solvents. However, cellulose derivatives such as CA and methyl cellulose are the common precursors to prepare cellulose nanofibers. Cellulose, for example, does not have an apparent melting point, but CA melts at around 227–277 °C and CA nanofiber loses its fibrous morphology when exposed to high-temperature thermal treatment . TherefoSince the electrode active materials determine the efficiency of the supercapacitor, tunning the right morphology of nanofiber-based materials can greatly influence the energy density of the supercapacitor. The effect of various morphological parameters on the performance of the supercapacitor is presented in this section.−1) was attributed to the largest surface area (1355 m2 g−1 for 7:3 PAN/CA ratio).Fiber surface area: For an ideal carbon electrode, a large surface area may provide ample electrode/electrolyte interfaces for ion or charge storage. Supercapacitors energy storing capacity is substantially enhanced with increased real surface area and maximized pore size for delivery of carbon materials without losing electrical conductivity . C. Ma ePorosity: Suitable porosity in materials is necessary for the transport of electrolytes and ion storage. Thus, selected pores in the electrode should combine ion buffering reservoirs (macropores), strong channel transports (mesopores), and ion storage sites (micropores) . J. Kim −2. Highest electrical conductivity at smaller fiber diameter is due to high surface area and less defects on the fiber structures. Fiber diameter: Nanofibers with lower fiber diameter have a much higher specific surface area with fewer defects which results in better electrochemical performance. Y. lie et al.  showed t−1). Hollow fibrous morphology has also been reported by B. Yu et al. [2 g−1. High porosity is attributed to the evaporation of ethanol  during spinning.Disordered fibrous morphology: The ordered arrangement of fibers is another factor that greatly influences the performance of the fabricated supercapacitor. M. Cho et al.  reportedu et al.  preparedLignin is the second most abundant natural bioresource material, after cellulose. It provides structural supports to plants because of its rigid nature. According to the International Lignin Institute, there are approximately 300 billion metric tons of lignin on earth with an annual estimated production of 40 to 50 million tons as by-products of the pulp and paper industries and biorefineries. Lignin has a high carbon content, almost 60–65%, which indicates a possible high yield following carbon fiber processing . Carbon 3PO4 nanofibers were prepared via coaxial electrospinning technique of Alcell lignin in ethanol (core spinning solution) and pure ethanol (shell spinning solution) [3PO4 in the precursor solution. H3PO4 could effectively dehydrate lignin phenolic-OH group to form phospholipid bonds between lignin molecules, thereby increasing the spinnability of lignin [3PO4 and IPDI, respectively. Foreign elements can be introduced into lignin precursor solution to alter the non-linear and randomly entangled numerous C-C and ether bonds which makes lignin rigid and difficult to electrospin. Using a simple heated single spinneret system, Tunnapat and Surawut  were ablolution) . Electrof lignin . Lignin f lignin . IPDI coDespite natural abundance of lignin and high surface area of lignin nanofibers, their poor electrical properties result in poor electrochemical performance of the lignin-based electrode. To improve the spinnability and morphological properties of lignin nanofiber-based electrode, lignin can be blended with other binding polymers. Similarly, blending lignin with other binders enhances the electrochemical properties of the prepared nanofibers. In this section, the effect of various binders on electrospun lignin nanofibers reported in our included articles are discussed. The processing conditions for reported polymers blended with lignin for application in supercapacitor devices are summarized in Some of the major polymeric binders reported in Polyacrylonitrile (PAN): Because of the excellent flexibility and fiber formation ability of PAN, Lignin has been blended with PAN to produce nitrogen-rich nanofibers with good plasticity . X. WangIn another study, butyric anhydride (BA) was added into lignin/PAN precursor solution prior to electrospinning . While PPolyvinyl alcohol (PVA): Although nanofibers cannot be fabricated from lignin alone due to its heterogeneity and branching structure, electrospun lignin/PVA nanofibers showed impressive electrochemical properties in addition to interwoven beads free nanofibers. For comparison, pure PVA nanofibers were equally synthesized. Compared to pure PVA nanofibers, lignin/PVA nanofibers show smaller fiber diameter, which increases with increasing lignin concentration . A signi2 shell material. A schematic illustration of the fabrication of the composite electrode materials is shown in Poly (methyl methacrylate) (PMMA): Using coaxial electrospinning, M Cao et al.  prepared3)2·6H2O nanofibers were reported [3)2·6H2O in the precursor solution. Therefore, PVP only acted as a sacrificial polymer to ease the spinning of lignin into nanofiber and to increase its porosity during carbonization.Polyvinylpyrrolidone (PVP): Electrospun lignin/PVP and lignin/PVP/Mg3 in the precursor solution [Poly(ethylene oxide) (PEO): Using lignin/PEO/Fe(acac)solution . Howeversolution . The con2 improved interface miscibility of double capillary and tailored porosity [2 decorated lignin nanofiber surface with nanowhiskers improved electrochemical performance of lignin-based carbon nanofiber [2O4 formed a high-performance hybrid supercapacitor with lignin [3)2·6H2O produced hierarchical porous lignin-based nanofibers with very high specific capacitance [3 prepared lignin-based hollow carbon nanofibers with superior electrochemical performance [Inorganic additives: Inorganic compounds can be added into lignin precursor solution to modify lignin structure, enabling spinnability and improving quality and performance of resultant nanofiber. For instance, SiOporosity , MnO2 deanofiber , NiCo2O4h lignin , Mg(NO3)acitance  and Fe of precursor solution: For different electrospinning conditions, parameters influence fiber morphology differently. However, the concentration of the precursor solution has been reported to have a major influence on fiber diameter ,76,77. A2 at 9 kV. The formation of beads could be attributed to a low voltage which could not sufficiently stretch the jet during spinning. Also, at low voltage, the electric field is not strong enough to completely ionize the polymer solution, letting some of the solvents be trapped in form of beads. In another study reported by F. Mateos et al. [3PO4 fiber with an average fiber diameter of 1–4 µm was prepared at spinning voltage of 40 kV. Thicker nanofibers produced could be attributed to high voltage because higher voltage mostly results in thicker fiber diameter.Applied voltage: The effect of applied voltage depends on the interplay between electrostatic force and surface tension. Nanofibers are formed during electrospinning only when there is enough electric force to just overcome the surface tension of the polymer at the nozzle tip. However, higher voltage results in thicker fibers while very low voltage form droplets . X. Wangs et al. , lignin/Flow rate: At a higher flow rate, the solvents do not have sufficient time to evaporate before reaching the current collector. This results in the trapping of the residual solvent on the current collector to form beads. Also, a high flow rate affects ambient condition of the electrospinning environment which could have an adverse effect on fiber morphology . In a stDistance between nozzle and collector: The effect of spinning distance varies depending on the concentration of the precursor solution and applied voltage. However, too long or too short spinning distance has been seen in many reports to affect the quality of the prepared nanofiber. When the distance between the spinneret and the current collector is too close, beads are formed due to partial evaporation of the solvent . SimilarThe energy and power density of a supercapacitor is shown in Equations (1) and (2) ,54.(1)E−1 and capacitance retention of 90% after 6000 cycles at 2 Ag−1. Alternatively, X. Ma et al. [2. The fabricated supercapacitor exhibits a specific capacitance of 84 Whkg−1 and capacitance retention of 92% after 10,000 cycles at 2 Ag−1. An appreciable increase in performance was due to the pseudocapacitive behavior of MnO2. Lignin-based electrode can equally be prepared by coating the active material on a conducting substrate. In such cases, a binder is required to bind the active material to the substrate. Z. Dai et al. [−1 and capacitance retention of 94.5% after 5000 cycles.C. Lai et al.  fabricata et al.  reportedi et al.  reportedThe fascinating characteristics of lignin and cellulose nanofibers such as low cost, high carbon performance, wide-field, mechanical stability, and environmental sustainability make them promising candidates for carbon-based EDLC electrode materials. Lignin and cellulose nanofibers can be combined into lignin/cellulose nanofibers to optimize the advantages of lignin and cellulose biomass materials as energy storage devices . PhysicaLignin/CA nanofibers were obtained from continuous dehydration of phenolic hydroxyl group of lignin and cellulosic hydroxyl group to create electron-deficient oxygen atoms. These oxygen atoms can successfully combine with electron-rich atoms from binding agents to form stable bonds between lignin and cellulose acetate . Early aIn an attempt to avoid the morphological collapse of lignin/cellulose nanofibers, M. Schreiber et al.  treated 3PO4) into lignin/CA precursor solution, stable phospholipid bonds were reported to blend poplar lignin and cellulose acetate [3PO4 concentration could be attributed to successful dehydration of hydroxyl group from both lignin and CA by H3PO4 leading to interphase miscibility. In another paper, epichlorohydrin (ECH) was added to lignin/CA precursor solution to prepare electrospun lignin/CA nanofibers [By adding phosphoric acid  is more defect-free, has greater surface area, more active functional groups, and enhanced chemical modification facility than conventional cellulose . Based oHollow nanofibers from electrospun acetylated cellulose nanofibril/silicone oil/chloroform and lignin/PAN as core and shell materials, respectively, were reported . Althoug−1 and a high energy density of 37 Whkg−1. Alternatively, a homogenous slurry containing lignin/CA , carbon black (conductive additive), and PTFE (binder) were coated onto nickel foam (current collector) to form the electrode [An EDLC comprises of four basic components: (1) porous electrode whose active material determines the efficiency of the EDLC, (2) electrolytes which fill the spaces between the electrodes so that ions move through them, (3) ion-permeable separator that allows charged ions from an electrolyte to be moved but not from electrodes, and (4) current collectors that function as conductive devices, capturing and distributing the currents from active materials to the external circuit ,90,91,92lectrode ,83. According to literature, electrochemical performance analysis using cycle voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge (GCD) was used to study nanofiber energy storage mechanisms. All lignin/CA-based carbon nanofibers exhibit high specific capacitance in aqueous electrolytes. This could be attributed to effective cross-linkage between lignin and cellulose leading to effective transport of electrolyte ions. Since the excellent properties of lignin/cellulose acetate nanofibers are attributed to the stable interaction between the phenolic hydroxyl group of lignin and acetyl group of CA, we can compare the performance of lignin/CA nanofibers prepared using different crosslinkers. For an accurate comparison, 3PO4 should have the highest energy density since it has the highest surface area. Contrarily, lignin/CA/ECH recorded the highest energy density despite having the lowest surface area. Lower energy density in the other nanofibers could be attributed to excessive tiny pores which were inaccessible by electrolyte ions. Furthermore, lignin/CA/ECH exhibits the highest specific capacitance which could possibly be due to suitable pore volumes that allow for easy passage of electrolyte ions. Therefore, high energy density in lignin/CA/ECH could be due to high specific capacitance, since the energy density of supercapacitor is proportional to the specific capacitance. The phosphated lignin/CA exhibit the highest carbon content (39.7%) after thermal treatment. This could be attributed to continuous dehydration of phenolic groups in lignin to form stable phospholipid bonds between lignin and CA during phosphoric acid treatment, thus resulting in better thermodynamic stability. Similarly, IPDI cross-linked lignin/CA exhibit the lowest carbon yield because excessive covalent bonds could increase the chances of molecular branched chains breaking, thus decreasing the molecular thermodynamic stability. The energy density of a supercapacitor improves as the average surface area improve . Thus, hThe natural abundance and inherent mechanical flexibility of cellulose make electrospun cellulose nanofiber a fascinating material for flexible supercapacitor. However, the morphological collapse of electrospun cellulose nanofibers during carbonization process remains a serious challenge. Thus, the energy density of cellulose nanofibers is limited by the melting of the nanofibers during carbonization due to the oxidation weightlessness of cellulose at high temperatures . To prodDue to the low molecular weight and entangled structure of lignin, it is difficult to produce fine nanofibers from lignin by electrospinning technique. To produce electrospun lignin nanofibers, lignin has to be blended with some additives that can modify the structural units of lignin ,60,69. E3PO4) were used to prepare CNFs from lignin/CA precursor [Obtaining a nanofiber stable lignin/cellulose nanofiber will is a great achievement in biomass-based supercapacitor not only because of natural abundance and renewable nature of lignin and cellulose, but also because the resultant nanofiber will have the combined properties of lignin and cellulose materials. By mimicking natural interactions of lignin and cellulose in trees, Q. Cao et al. , reporterecursor . InteresThe use of lignin/cellulose nanofibers as electrode materials is innovative for electrochemical double-layer capacitors. This section outlined a few motivations behind using lignin and cellulose nanofibers over other carbon-based nanofibers as supercapacitors electrode materials.2O3/SiO2 to produce defective pores. Supercapacitor electrodes from extremely porous surface materials improve energy storage by providing electrolytic ion pathways that increase the working active volume. Besides, CNF doping increases electric conductivity by supplying electrons for active delocalization of pi-electrons [Both lignin and cellulose are biomacromolecules that are found abundantly in nature. The extraction processes of these materials are equally simple and less energy consuming. Thus, lignin/cellulose nanofibers are economically favorable and readily available precursor materials for making carbon nanofiber ,102,103.lectrons ,70,105.The addition of cellulose nanocrystals into lignin/polymer precursor solution reduced phase separation and improved the degree of fiber geometry retention after carbonization ,86,87. CDespite the various advantages of lignin/cellulose nanofiber electrode materials in the field of energy storage, it is difficult to completely embrace these materials due to some of their major limitations. This section will identify the numerous obstacles to the large-scale application of lignin/cellulose-based electrode materials.While lignin and cellulose are readily available in nature, the use of lignin and cellulose nanofibers in energy storage remains a laboratory application. This, among other factors, can be due to the carbon yield of both lignin and cellulose nanofibers after thermal treatment. After the carbonization process, carbon yield of lignin and cellulose fall as low as 40% and 10–30%, respectively . Poor elThe electrospinning technique has the ability to produce fine nanofibers with controlled fiber morphology. However, the quality of nanofiber produced is determined by so many variables. The difficulty in optimizing all these parameters and their collective influence on the prepared nanofiber at the same time remains a serious challenge . This isTo address the aforementioned challenges and to meet the current demand for portable and flexible supercapacitors, the most important recommendation is to develop a flexible high-performance solid-state supercapacitor from cost-effective and environmentally friendly materials. Although lignin/cellulose nanofibers electrodes show excellent cycle stability and tailored porosity, their energy density is much smaller than those of other carbon-based electrodes. Therefore, there is a need to improve the performance of lignin/cellulose nanofiber electrodes to compete with other carbon-based electrodes like PAN, graphene, and carbon nanotube without compromising power density. This section will provide a reference for other researchers interested in developing biomass-based supercapacitors as an alternative to the conventional petroleum product-based supercapacitors.Activation is an effective way of improving the performance of electrospun nanofibers. The activation process can be performed via a physical method (using carbon dioxide or steam) or chemical method . Defective pores produced after the activation process serve as suitable electrolyte ions transport channels ,55. TherGenerally, carbon nanofibers with optimum performance were obtained at a limited time, energy, and resource consumption. This process involves the use of optimization models like response surface methodology to optimize parameters whose influence could have direct or interactive effects on nanofiber properties. The model uses central composite design (CCD) to construct experimental design and analysis of variance (ANOVA) to establish statistical validation of regression models as well as to study the interaction of input parameters  Hence, eConventional supercapacitors are composed of current collectors, electrodes, electrolytes, separators, binders, and conductive additives. This makes the supercapacitor rigid and cumbersome to meet practical requirements for portable devices. Electrospun activated carbon fiber network (ACFN) exhibits outstanding performance due to its flexibility, large surface area, excellent mechanical flexibility, and particularly good electrical conductivity. Besides, freestanding ACFNs do not require conductive additives and binders when used as supercapacitors ,109. ThuElectrospun lignin and cellulose nanofiber-based electrodes have a wide surface area, good porosity, mechanical stability, and excellent cycle stability. However, the energy density of these electrode materials is quite low compared to other carbon-based electrode materials like PAN, graphene, etc. Similarly, carbon nanofibers produced from cellulosic precursors undergo morphological collapse during carbonization due to the low thermal stability of cellulose derivatives. Deacetylation of CA prior to thermal treatment improves the thermal stability of CA-based carbon nanofibers.Electrospinning lignin into nanofibers is unrealistic due to the hierarchical and entangled structure of lignin. However, lignin can be easily blended with other binders to produce fine lignin-based nanofibers. Different binders influence electrospun lignin nanofiber differently.Electrospinning lignin and cellulose precursor solution resulted in nanofiber with phases separated into lignin and cellulose domains. However, incorporating a suitable crosslinker resolves the problem of phase separation. Resultant nanofibers exhibit thermal stability of lignin and flexibility of CA.Lignin/cellulose nanofiber, if explored extensively, can serve as ideal electrode materials for next-generation supercapacitors as an alternative to petroleum-based carbon nanofibersBiomass carbon nanofiber technology is one of the most active research areas in energy storage devices, especially EDLCs. The main objective of this systematic review is to highlight the state of the art research on electrospun lignin and cellulose nanofibers for application in supercapacitors and to provide directions of future research on the area. A rigorous scientific approach was employed to screen the eligibility of included articles and taxonomy of literature was provided from the most relevant articles included in the literature review. Apart from the articles in the taxonomy of literature, nine other articles were also included in our critical review and development of the research framework. These articles did not strictly meet our inclusion criteria, but they contain vital information that helped in developing the research framework. From our included literature, four main categories were discussed: reviews, studies on electrospun lignin nanofibers, cellulose nanofibers, and lignin/cellulose nanofibers. While studies on electrospun lignin and cellulose-based supercapacitors are considered adequate, very limited studies were reported on lignin/cellulose based supercapacitors. However, the reported studies on lignin/cellulose-based supercapacitors indicate a new research direction for biomass-based supercapacitors. From the articles reviewed in this study, researchers stated some major challenges related to large scale application of these special class of electrode materials. In the same vein, recommendations were given to mitigate these challenges. Specifically, comments and suggestions include: Statistical software like response surface methodology (RSM) and intelligent algorithms like artificial neural network (ANN) have been employed to optimize electrospinning parameters of different precursor materials. However, too many experimental runs are required to consider all electrospinning parameters at the same time. Developing optimization software that will consider all electrospinning parameters from a few experimental runs will be revolutionary, not for electrospinning lignin/cellulose nanofiber alone but for all types of fibers.The uniqueness of electrospun lignin/CA nanofibers is the formation of high-quality nanofibers with outstanding properties of lignin and CA combined. This property is determined to a large extent by the effectiveness of the linking unit between lignin and CA. Investigating novel crosslinkers that could ensure stable and effective crosslinking reaction as well as improve the performance of lignin/cellulose nanofiber greatly is an exotic area to explore. Interestingly, authors are currently working on this.To further improve the performance of electrospun lignin/cellulose nanofibers, researchers should focus on preparing core–shell and hollow nanofibers. This will improve the surface area of the prepared nanofiber as well as combine the performance of different precursor materials used. Employing other techniques—such as hydrothermal, template synthesis, in situ polymerization, etc.—to augment electrospinning technique is also a wonderful research direction for fabricating lignin/cellulose-based supercapacitors.A hybrid supercapacitor benefits from the performance of an EDLC (high energy density) and pseudocapacitors (high power density). Due to high surface area, high porosity, mechanical and thermal stability, excellent cycle life, and sustainable nature of lignin/cellulose nanofibers, electrospun lignin/cellulose based asymmetric supercapacitors would be an exotic research area. Researchers should focus on asymmetric supercapacitors comprising of lignin/cellulose nanofiber as an EDLC electrode and conducting polymer, MOF, or metal oxide as a pseudocapacitive electrode. Authors are also working on this.The development of flexible solid-state supercapacitors is taking a new dimension with the recent demand for flexible electronic devices. To meet this demand, fabricating an all-solid-state lignin/cellulose-based supercapacitor is an interesting area to explore because of its mechanical flexibility and high performance. In our next article, we will report the performance of all-solid-state supercapacitor derived from lignin/cellulose nanofiber and PVA-based electrolyte.The efficiency of flexible supercapacitors decreases significantly due to the distortion in the configuration of the supercapacitor after many bending cycles. Researchers need to concentrate on incorporating self-healing materials into lignin/cellulose nanofibers to allow the supercapacitor to heal itself following persistent bending cycles.Fabricating cheap and environmentally friendly electrode materials with combined properties of lignin and cellulose could be ideal for next-generation electrospun carbon nanofiber-based supercapacitors. Therefore, future studies must focus on the mechanism of interaction between lignin/cellulose material and other materials at a microscopic level. Similarly, researchers in this area need to adopt combinations of various techniques to improve the overall performance of supercapacitors derived from lignin/cellulose precursors. In effect, the following points will help researches in this area with research directions for future studies:


The COVID-19 pandemic has created a global health crisis that is affecting economies and societies worldwide. During times of uncertainty and unexpected change, people have turned to social media platforms as communication tools and primary information sources. Platforms such as Twitter and Sina Weibo have allowed communities to share discussion and emotional support; they also play important roles for individuals, governments, and organizations in exchanging information and expressing opinions. However, research that studies the main concerns expressed by social media users during the pandemic is limited.The aim of this study was to examine the main concerns raised and discussed by citizens on Sina Weibo, the largest social media platform in China, during the COVID-19 pandemic.New Coronavirus Pneumonia, New Coronavirus, and COVID-19) to investigate concerns raised by Sina Weibo users. Textual information and metadata  of microblog posts published between December 1, 2019, and July 32, 2020, were collected. After segmenting the words of the collected text, we used a topic modeling technique, latent Dirichlet allocation (LDA), to identify the most common topics posted by users. We analyzed the emotional tendencies of the topics, calculated the proportional distribution of the topics, performed user behavior analysis on the topics using data collected from the number of likes, comments, and retweets, and studied the changes in user concerns and differences in participation between citizens living in different regions of mainland China.We used a web crawler tool and a set of predefined search terms (Based on the 203,191 eligible microblog posts collected, we identified 17 topics and grouped them into 8 themes. These topics were pandemic statistics, domestic epidemic, epidemics in other countries worldwide, COVID-19 treatments, medical resources, economic shock, quarantine and investigation, patients’ outcry for help, work and production resumption, psychological influence, joint prevention and control, material donation, epidemics in neighboring countries, vaccine development, fueling and saluting antiepidemic action, detection, and study resumption. The mean sentiment was positive for 11 topics and negative for 6 topics. The topic with the highest mean of retweets was domestic epidemic, while the topic with the highest mean of likes was quarantine and investigation.Concerns expressed by social media users are highly correlated with the evolution of the global pandemic. During the COVID-19 pandemic, social media has provided a platform for Chinese government departments and organizations to better understand public concerns and demands. Similarly, social media has provided channels to disseminate information about epidemic prevention and has influenced public attitudes and behaviors. Government departments, especially those related to health, can create appropriate policies in a timely manner through monitoring social media platforms to guide public opinion and behavior during epidemics. On June 29, 2020, the World Health Organization (WHO) marked the six-month anniversary of the COVID-19 outbreak . The gloExtant studies have demonstrated that timely understanding of public attitudes and demands plays an important role in responding to public crises ,5. Most A large body of literature has examined the role of social media in analyzing public behavior, attitudes, and responses during times of public crisis. Researchers have mainly focused on the platform functionality, user behavior characteristics, and use of social media during crises. As most platforms are freely available in the public domain , they haNew Coronavirus Pneumonia, Coronavirus, New Coronavirus, and COVID-19. In addition to the textual content collected, we sourced the metadata for each microblogged post, including number of likes, number of comments, number of retweets, publishing time, and publishing location. The location information in the metadata refers to the registered address of the Sina Weibo account associated with a microblog post. To obtain these data, we used the advanced search functionality of Sina Weibo.Sina Weibo is the leading microblogging platform in China; it enables users to send and receive short character-limited posts and retrieve textual content by searching for specified keywords over a defined date range. Using this functionality, we collected shared microblog posts related to COVID-19 during the time period of December 1, 2019, to July 31, 2020. The Octopus web crawler tool was used to search for predefined keywords, including In the Chinese language, there is no obvious separation between words. Therefore, for the purpose of completing the latent Dirichlet allocation (LDA) processing tasks, it was necessary to add obvious separators between words. We performed Chinese segmentation on the textual content collected during data preprocessing. A widely used Chinese word segmentation tool, ictclas, was employed to divide microblog posts into groups of words separated by spaces. For example, the microblog post “JD announced the donation of 1 million medical masks and 60,000 pieces of medical supplies to Wuhan City in batches” was segmented into “JD / announced / the / donation of / 1 million medical masks / and / 60,000 pieces of / medical supplies / to / Wuhan City / in batches”. In addition, we removed stop words  from theWe applied topic modeling by specifying the number of topics required by the LDA to separate the set of microblog posts into defined clusters . LDA canLDA is a widely used topic modeling algorithm . AccordiTo determine the appropriate number of LDA topics, we used the coherence score to draw judgments; this method has been proposed to be useful for selecting a suitable number of LDA topics . ThroughSubsequently, we conducted manual analysis and selected representative and high-proportion keywords from the top 30 keywords of each topic. Next, consensus was reached on the 17 topics and related keywords. Lastly, we used these keywords to classify the microblog posts; we also obtained the number of microblog posts under each topic and the proportion of each topic in all related microblogs. Examples of microblog posts for each topic are provided in An example microblog is as follows:The sudden outbreak of new coronal pneumonia has had an impact on the country’s economic operation. It has brought a negative GDP growth and an increasingly complicated international and domestic environment. However, under the strong hedging of the counter-cyclical adjustment policy, the resumption of production has advanced rapidly, while the main economic indicators show a rebound in March, and the decline rate narrowed significantly.This microblog post can be categorized into two different topics: work and production resumption and economic shock.We also performed other analyses of the collected data, such as sentiment analysis. The sentiment scores varied between –1.0 and 1.0, with –1.0 being the most negative text and 1.0 being the most positive text. In addition, we calculated the interaction rate of users for each topic by analyzing the average number of retweets, likes, and comments per topic. Finally, using the publishing time and location, we analyzed changes in user concerns based on the time period and differences in user engagement in discussions related to COVID-19 based on the Chinese region.Using the web crawler tool and predefined search terms, we obtained a total of 203,191 microblog posts from the Sina Weibo platform that were shared between December 1, 2019, and July 31, 2020.According to the results obtained from the LDA and the keywords involved in each topic, we were able to group the topics into 8 themes: (1) patient admission; (2) treatment and research; (3) treatment resources; (4) fighting the epidemic together; (5) work to restore order; (6) prevention and control measures of COVID-19; (7) domestic and overseas pandemic situation; and (8) impact of COVID-19. The corresponding terms for each topic are shown in The topic contained in this theme is patients’ outcry for help, which relates to patients who have or may have contracted COVID-19 and their treatment situation. The cries for help of patients who are awaiting treatment have attracted widespread attention, while the subsequent reception and treatment of these patients has also attracted significant attention.This theme contains two topics. The first topic is COVID-19 treatments. In this topic, the recovery of patients with COVID-19 received widespread attention, such as the number of people discharged from hospital and the number of people who recovered. At the same time, treatment methods have attracted widespread public attention, such as treatments using Chinese medicine. The second topic in this theme is vaccine development. In this topic, research progress in relation to vaccines and their clinical trials has attracted much comment. Meanwhile, there has been widespread debate about whether vaccines can achieve the goal of preventing the virus.The topic in this theme is medical resources. This topic focuses on core aspects of medical resources; medical staff and hospital wards, the allocation and integration of medical resources, and the establishment of temporary hospitals such as mobile cabin hospitals are all of general concern.fighting and defeat represent the general attitude of Sina Weibo users towards the fight against COVID-19. The second aspect, cooperation in the fight against the pandemic, is often discussed; key phrases such as work with one heart and unity is strength were frequently mentioned.This theme includes two topics. The first topic is material donation. In the early stages of fighting the epidemic in mainland China, masks and other antiepidemic materials were extremely scarce. This issue aroused widespread concern, and the donation of various antiepidemic materials became an active topic. The second topic is fueling and saluting antiepidemic action. This topic includes two aspects; the first aspect is the confidence and determination to beat the pandemic. Keywords such as As the spread of COVID-19 in mainland China is gradually being controlled, the restoration of production and resumption of normal ways of living is becoming an active topic. This topic includes two subtopics. The first subtopic relates to work and production resumption. The progress and arrangements of the resumption of work and production have aroused widespread concern and discussion. This work, which is aimed at restoring normal production and operational order, has received widespread support from the Chinese public. The second topic is study resumption, which mainly involves two aspects: first, the time when students of all ages will return to school, and second, the time for the national college entrance examination.This theme includes three topics. The first topic is quarantine and investigation, which includes two aspects: the investigation of symptoms, such as cough and fever, and quarantine periods. In particular, the 14-day quarantine period has become standard.The second topic is joint prevention and control. Taking measures of joint prevention and control and establishing a headquarters are important actions taken by the Chinese government in response to the epidemic. This action is also key for the Chinese government to contain the epidemic in the short term. Correspondingly, it has also been widely recognized and is of great concern to the public.The last topic is detection. The main content related to this topic is nucleic acid detection, which is an important way to establish which patients have COVID-10 or have been infected with SARS-CoV-2. The topic of detection has aroused widespread discussion.Four topics are included in this theme. The first topic is domestic epidemic. On the one hand, because Hubei and Wuhan are the main battlefields in the fight against the epidemic in China, the epidemic situation in these regions has received a significant amount of attention. On the other hand, the spread of the epidemic in China is also of great concern to the public. Epidemics in neighboring countries is the second topic. The peak of this topic appeared in mid-to-late February 2020, when the epidemic began to spread from China to neighboring countries, such as Japan, South Korea, and Russia. This has aroused heated discussion among Sina Weibo users.The third topic is epidemics in other countries worldwide. At the time when this topic appeared, the epidemic had spread globally; therefore, the topic included many countries and regions. The United States, as the country hit hardest by the epidemic, has attracted widespread attention from Sina Weibo microbloggers. In particular, US President Donald Trump’s statement that if COVID-19 deaths in the United States could be controlled to less than 100,000, “we all together have done a very good job”  has beenThis theme has two topics. The first is economic shock. This topic mainly refers to the negative impact of the epidemic on economies and markets worldwide. The second topic is psychological influence. On the one hand, the outbreak of the epidemic has delivered a substantial psychological blow to the public, and emotions such as worry and fear have spread among citizens. On the other hand, the public also hopes and believes that the fight against the epidemic will be successful, and they remain in an optimistic mood.To understand the specific degrees of concern for the various topics identified, we established the number and proportion of each topic by counting the number of microblog posts per topic. For example, the proportion of each topic is the number of microblog posts shared about the topic divided by the total number of microblogs . The results of our analysis are shown in As shown in The treatment of COVID-19 raised high expectations and received attention from the public for a long period, with a proportion of 11.1% . Medical resources are particularly important in the fight against the epidemic, and this topic accounts for 10.9% of posts . The great impact of COVID-19 on the economy is closely related to the interests of the public; therefore, the topic of economic shock also received a high degree of attention, ranked sixth with 10.1% of posts . As one of the most important measures for controlling and preventing the spread of COVID-19, the topic of detection and quarantine has received considerable attention at all stages of the pandemic since its outbreak, accounting for 9.12% of total posts . The topic of patients’ outcry for help also attracted widespread attention, accounting for 8.61% of total posts .An important measure to restore economic order in China is work and production resumption, which is closely related to citizens’ lives. The percentage of microblog posts on this topic is 7.83% . The epidemic also greatly affected the public psychologically; therefore, the topic of psychological impact also received much attention, with a post percentage of 7.12% . Joint prevention and control and material donations have received a certain amount of attention. These two topics ranked 11th and 12th, with proportions of 6.13%  and 6.11% , respectively. The situation in neighboring countries also aroused comment from Sina Weibo users, although the duration was short-lived; accordingly, this topic ranks 13th, with 5.90% of posts .The development of vaccines has also been discussed by the public, with related microblog posts accounting for 4.64% of posts . The fight against COVID-19 is a national battle in which citizens fuel discussions on how to overcome the pandemic. The percentage of posts relating to this topic was 4.63% . As an important means of identifying patients who are infected with COVID-19, detection has also received a certain degree of attention, accounting for 4.39% . After the pandemic in Mainland China was controlled, study resumption was also mentioned; however, compared to other topics, the degree of concern in this area is relatively low, accounting for only 3.39% of total posts .Based on the collected microblog metadata, including the numbers of retweets, comments, and likes, we were able to analyze the levels of interaction between users for each topic. At the same time, we performed a sentiment analysis to obtain the sentiment value for each topic. It should be noted that the data reported on in this article included microblogs posted by opinion leaders. The numbers of retweets, comments, and likes for these microblog posts were high. For example, for the post “Zhong Nanshan said that Lianhuaqingwen capsules were proved to be effective in the treatment of COVID-19”, the numbers of retweets, comments, and likes were 13,599, 19,022, and 344,780, respectively. Therefore, the average numbers of retweets, comments, and likes in this paper are high.From By using the publishing times of the microblog posts, we were able to analyze the change in users’ concerns during different time periods. Similarly, we used the publishing location to analyze the differences in user engagement in discussions relating to COVID-19 between different regions in China. Our study, conducted from December 1, 2019, to July 31, 2020, identified 8 themes with 17 topics. Among these topics, content related to COVID-19 treatment aroused great attention, particularly content related to patients’ outcry for help and emotions such as anxiety and panic. Due to the widespread negative emotions on Sina Weibo, misinformation and rumors can more readily influence public opinions, which negatively impacts antiepidemic actions. In addition, Sina Weibo users showed much interest in the progress of the treatment of COVID-19 and of vaccine development. At the same time, there has been considerable focus and discussion among a large number of Sina Weibo users on whether medical resources are sufficient and whether they can meet the treatment needs of patients.Sina Weibo users also focused heavily on the real-time situation of the epidemic at home and abroad. In particular, many microblog posts contained real-time data on the development of the epidemic. Further, Sina Weibo users not only paid attention to the epidemic situation in the Chinese mainland but also greatly discussed the development and evolution of the epidemic in neighboring countries and the rest of the world. In addition, epidemic prevention and control measures, order restoration measures in the later stage of the epidemic, and the impact of the epidemic are included in the 17 topics that received attention from Sina Weibo users.Our findings show that December 2019 and January 2020 were the key periods of the response to the COVID-19 pandemic, with domestic epidemic and pandemic statistics receiving much attention during this period. At the same time, the sudden outbreak also affected the public psychologically. On the one hand, the public believes that the fight against the epidemic will eventually be won; on the other hand, emotions such as fear and worry are also spreading among the public.February and March 2020 were critical periods for curbing the spread of the epidemic in mainland China . During From June to July 2020, the number of infections and deaths caused by COVID-19 worldwide continued to rise. The focus of Sina Weibo users shifted from China to the rest of the world, and the users began to pay greater attention to epidemics in other countries and the growing pandemic statistics.According to the spatial distribution information collected on microblog posts, discussions related to COVID-19 differed among the various regions of China. The six regions with the highest degrees of participation were Hubei Province, Henan Province, Guangdong Province, Anhui Province, Jiangsu Province, and Hunan Province. Hubei Province is the epicenter of the COVID-19 epidemic in China, while Henan Province, Hunan Province, and Anhui Province are all adjacent to Hubei Province, with many citizens working in Hubei Province. Jiangsu Province, as an economically developed region, has a relatively high mobility rate of personnel. As a result, Sina Weibo users in these provinces were more likely to be concerned about the pandemic. Guangdong Province experienced the severe acute respiratory syndrome (SARS) epidemic in 2003, which is an important reason why more users in this region participated in discussions on the COVID-19 pandemic.A recent study reported the main topics related to COVID-19 that are of concern to Twitter users . The autSecond, Sina Weibo users focus on the real-time status of the epidemic. This includes not only the domestic epidemic situation, but also the development of the epidemic abroad. At the same time, in the middle and late stages of the epidemic, work to restore order, such as work and production resumption and study resumption, have attracted widespread attention. The following two reasons may have led to the emergence of the above unique concerns. First, as Chinese citizens were the first nation to experience the COVID-19 pandemic, they are more sensitive to the development and changes of the epidemic than people in other countries, and second, as the country that has demonstrated the most effective epidemic prevention and control, China has established conditions to restore order .The results of our sentiment analysis show that of the 17 topics, the numbers of topics with positive sentiment values and negative sentiment values are 11 and 6, respectively; for most topics, users have no obvious positive or negative emotional tendencies. However, it should be noted that there are still some topics in which the emotional value of a certain aspect is significant. For example, topics such as pandemic statistics demonstrated negative emotional tendencies. The continuous accumulation and spread of negative emotions on Sina Weibo may trigger irrational behavior among citizens, causing users to be affected by rumors or extreme emotions , such asWith the outbreak and spread of COVID-19 worldwide, citizens have turned to social media channels, such as Sina Weibo, to share their opinions, seek clarity, and discuss topics related to the crisis. Previous studies have demonstrated that the analysis and control of public behavior and attitudes can effectively help governments cope in times of crisis . As manyIn this paper, we collected data from Sina Weibo and analyzed it from the viewpoints of quantity, proportion, emotion, and space-time distribution. We identified the degrees of attention and the emotional tendencies of users toward various topics related to COVID-19, and we determined the time distribution for each topic and the spatial differences of users’ participation in topic discussions. The results obtained enable deeper understanding of the views and attitudes of the public towards COVID-19, which is the premise of and basis for the prevention and control of this novel disease.This paper is based on the existing theories of predecessors, combined with the timely topic of COVID-19. Through analysis of Sina Weibo microblogs, practical conclusions are drawn from the topics related to COVID-19 that are of concern to the public. At the same time, it is undeniable that this article also presents some limitations. First, the microblog posts collected in this study only include some posts related to COVID-19, not all of them. Therefore, the summary of the main concerns of Sina Weibo users is not comprehensive. Secondly, the majority of Sina Weibo users are young; therefore, the results of our analysis are more representative of younger citizens. Finally, although the number of Sina Weibo users is relatively large in China, we cannot draw a rushed conclusion that opinions expressed on the web represent public opinion in general.The COVID-19 outbreak has had a crippling impact on the world economy and has presented numerous challenges to how people live and travel. Topics related to COVID-19 have attracted widespread attention and discussion on social media platforms, such as Sina Weibo. By analyzing the microblog posts of COVID-19 topics, we obtained the opinions of citizens on topics related to the virus which can lead to the identification of solutions to solve societal and economic problems . In ligh


P. methysticum). Kavalactones have been shown to possess diverse biological activities including sedation and anxiolysis . Kavain in particular has been demonstrated to show potent anti-inflammatory properties in various in vitro and animal models . A study in C. elegans reported that kavain increases lifespan by inhibiting advance glycation end-products (AGEs), which are known to suppress lifespan . Another study reported that kavain increases acetylcholine (ACh) transmission at the neuromuscular junction . Since loss in ACh transmission and increased formation of AGEs are closely linked to Aβ-pathology, we hypothesized that kavain may protect against Aβ-induced toxicity . We tested kavain in the C. elegans GMC101 strain that over-expresses human Aβ in body wall muscle cells . Kavain at a concentration of 40 and 80 μM was shown to increase lifespan, thus we decided to use a dose between these ranges . We observed GMC101 animals fed 50 μM kavain showed significantly less paralysis when shifted to the higher permissive temperature (25o C). The result shows that kavain suppresses Aβ-induced proteotoxicity.Kavain belongs to a group of lactone-based compounds collectively known as kavalactones, present in the pepper plant kava (oC). To these plates, 100 μl of E.coli OP50 was added to form a circular bacterial lawn on the center of each plate. Plates were then left inside the hood (lid closed) for drying. A 100 mM stock of compound was prepared in 100% DMSO and stored in small aliquots at -20°C. From the stock solution, 130 µl of the working drug (50 μM) or control-DMSO (0.05%) solution was prepared by mixing 1.5 μl of stock solution with 130 µl of sterile water and adding to the top of the 35 mm NGM plates (with 3 mL NGM agar) 48 hours post-bacterial seeding. Compound was distributed over the entire plate surface and allowed to dry in a sterile hood with the lid open for at least 1 hour. Plates were then allowed to sit at 20°C for 24 hours before use.NGM agar plates (35 mm) were prepared under sterile conditions in a laminar flow hood at room temperature , eggs accumulated close to the body, or if they failed to respond to touch-provoked movement with a platinum wire.Egg-lay synchronized populations of GMC101 animals were grown from eggs at 20dvIs100 [unc-54p::Aβ-1-42::unc-54 3′-UTR + mtl-2p::GFP]. [unc-54p::Aβ-1-42] expresses full-length human Aβ1-42 peptide in body wall muscle cells that aggregates in vivo. Kavain: Sigma Aldrich (#59780).GMC101:


The conductivity and viscosity of the TPU solution increased with the increasing ratio of TFE in the solvent system. The obtained electrospun TPU nanofibers fabricated from this novel solvent system showed smooth morphology and uniform diameter distribution. Mechanical strength of TPU nanofibers was improved using this new solvent system. Young’s modulus and tensile strength of the electrospun TPU nanofiber meshes first decreased and then increased, while the strain elongation ratio first increased and then decreased. The new solvent system significantly improves the fiber elongation ratio while maintaining the modulus and tensile strength. The chemical structure of the TPU was not affected by the TCM/TFE solvent system. Electrospun TPU nanofiber meshes prepared by using the TCM/TFE solvent system showed better cytocompatibility, which means the electrospun TPU fibrous scaffold has great potential in biomedical application.A novel Trichloromethane (TCM)/2,2,2-Trifluoroethanol (TFE) solvent system was developed for fabricating electrospun thermoplastic polyurethane (TPU) nanofibers. TPU solution stability made from this novel solvent system was improved compared to that from the traditional N, N-Dimethylformamide (DMF)/Tetrahydrofuran (THF) solvent system. The minimum TPU solution concentration that can be electrospun was decreased to 0.5%  Nanofibers have been widely used in tissue engineering and regenerative medicine ,2,3, andElectrospun solution properties are directly related to the solvent type. Solvents used to dissolve TPU must be highly polar organic solvents. Currently, several solution systems, mainly composed of 1,1,1,3,3,3,-hexafluoro-2-propanol (HFIP) , N,N-dimHerein, we fabricated TPU nanofibers from different solvent combinations (TCM and TFE). The manufactured nanofibrous meshes were then characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and mechanical property tests. The in vitro cytotoxicity of prepared nanofibers was tested using rat bone marrow mesenchymal stem cells (rMSCs).3) was obtained from BASF (Germany). 2,2,2-Trifluoroethanol , dimethylformamide , tetrahydrofuran  and trichlormethane were used as solvents to dissolve TPU. These materials and chemicals were used as received without further purification.Thermoplastic polyurethane , respectively. The mixture was stirred using a magnetic bar until the solution was uniform and free of bubbles. Based on previous studies [TCM and TFE were mixed at the volume ratio of 10:0, 9:1, 8:2, 7:3, 5:5, 4:6, 3:7 and 0:10. Then, the same amount of TPU was added to every mixture to prepare a spinning solution at a concentration of 0.5%, 5% and 8% . The measurement temperature was between 24 and 26 °C, and rotor speed was 60 rpm. The conductivity of the solutions was measured by DDS-307A conductivity meter made by Shanghai Instrument & Electronics Scientific Instrument Co., Ltd., Shanghai, China.Applied voltage of the electrospinning setup was 10–16 kV. The tip-to-collector distance was 10–15 cm. The feeding rate was set at 1 mL/h. The relative humidity of the environment was 30–60%. All the experiments were conducted at room temperature. The TPU nanofiber meshes obtained from electrospinning were dried in a vacuum-drying oven for 48 h to remove the residual organic solvent.A field emission scanning electron microscope  was used to characterize electrospun nanofiber morphology. The accelerating voltage was set at 8–10 kV. The diameter of electrospun nanofibers was measured by Image J 1.40G software, and the average diameter of nanofibers in each solution system was calculated. The number of nanofibers in each calculated group from each solution system was above 50.−1 at a scanning resolution of 2 cm−1.A TENSOR 27 FT-IR spectrometer  was used to characterize the molecular information of the electrospun nanofibers. The FT-IR spectra of the electrospun nanofibers were obtained over the range of 600–4000 cmTo examine the effect of a different volume ratio of TCM and TFE on the crystalline characteristics of electrospun nanofibers, XRD analysis was performed using a Rigaku D/max 2550 PC with Cu Ka radiation, operated at 40 kV, 300 mA, and a 5° (2θ) per min scanning rate.DSC  analysis was also performed to examine the crystalline information of the electrospun nanofibers. Each sample weighed between 5 to 8 mg. The instrument was calibrated with an indium standard. A nitrogen atmosphere (flow rate is 50 mL/min) was used throughout the scanning. The experiment was conducted from −20 to 270 °C at a heating rate of 10 °C/min.Tensile properties of the electrospun nanofibrous meshes were tested using a tabletop testing machine  equipped with a 500 N load cell. Rectangular-shaped specimens with a size of 50 mm (length) × 10 mm (wide) × 0.1−0.2 mm (thickness) were stretched at a constant cross-head speed of 10 mm/min at room temperature. Typical tensile properties of strength, Young’s modulus and strain-at-break were obtained from the tensile stress–strain curves.w/v). The solutions were stirred overnight till uniform and bubble-free. The electrospun nanofiber meshes were dried in a vacuum oven to remove the solvent completely. The nanofiber meshes were used to cover a coverslip with a 15 mm diameter. After that, the nanofiber meshes and coverslip were soaked in alcohol solution  from high-concentration to low-concentration for 15 min each and then washed twice in PBS  solution to complete the disinfection and sterilization. The 24 well plates were used for the cell test. There were five control groups with three multiple holes in each group. rMSCs were cultured in DMEM  supplemented with 10% FBS  and 1% penicillin/streptomycin  for 7 days . The medium was changed every 2 days. Then, the cells were isolated by 0.125% trypsin-EDTA solution  and counted using a hemocytometer and an optical microscope.The TPU solution was dissolved in the TCM/TFE and DMF/THF system at a concentration of 8%  for 15 min each time. Thereafter, the specimens were dried and mounted on aluminum holders and coated with gold for FE-SEM imaging.4 cells per well and cultured in an incubator. Cell viability was tested using CCK-8 assays .Cells were seeded onto each TPU fibrous membrane at a density of 1 × 10p < 0.05 was considered statistically significant.All values were exhibited as the mean ± standard error of at least three samples. Statistical analysis was performed using one-way ANOVA analysis with Tukey’s test included in Origin 8.0 software. w/v), TPU only swelled at VTCM/VTFE = 10/0, 9/1, 3/7 and 0/10. TPU can be dissolved and form a uniform and stable TPU solution when VTCM/ VTFE is 8/2, 7/3, 6/4, 5/5, 4/6. These solutions keep clear and transparent during long-term storage, and this is beneficial to industrial production.The TPU solution properties are the most important parameters that affect the resultant TPU nanofibers properties . PreviouDMF and THF were common solvents of TPU in previous studies ,22,23. Iw/v). Electrospun TPU nanofibers from TCM/TFE solvent show a smooth surface morphology and uniform diameter distribution, while electrospun TPU nanofibers from DMF/THF show many beads. There are several reasons for the formation of beads. One is the low solubility of TPU in the DMF/THF solvent, which results in the low crosslinks among the TPU polymer chains in the solution. The other is from the low volatility of DMF (saturated vapor pressure of 3.7 mmHg) in the DMF/THF solvent system. In this case, the solvent cannot completely volatilize, while the drops fly from the needle tip to the collector. Compared to DMF, TCM has a much higher volatility (saturated vapor pressure is 160 mmHg) [w/v), the solvent can volatilize in time and facilitate nanofibers formation. Therefore, TCM/TFE solvents improved the electrospinnability of TPU, which is beneficial for reducing the production cost and its use as a biological scaffold.It is well-known that polymer concentration plays an important role in maintaining the stability of electrospun jet . When th60 mmHg) . Even ifw/v), TPU solutions from both TCM/TFE and DMF/THF solvent systems could be electrospun into nanofibers with a smooth surface and uniform diameter distribution (w/v). TPU nanofibers prepared by electrospinning with different solvent ratios of TCM/TFE have smooth and bead-free morphology. As the TFE component in the solvent system increases, the surface roughness of the fiber first decreases and then increases. TPU nanofibers have the lowest surface roughness when the ratio of TCM/TFE is VTCM/VTFE = 5/5. Diameters of the nanofibers were (1032 ± 380) nm, (997 ± 226) nm, (1155 ± 161) nm, (2339 ± 628) nm for VTCM/VTFE = 8/2, 7/3, 5/5, 4/6, respectively , 1530 cm−1 (bending vibration of amide bond N-H) and 1223 cm−1 (C–N stretching vibration of amide bond) [2 at 2929 cm−1 [2 at 2830 cm−1, and the C=C skeleton vibration of aromatic benzene ring at 1600 cm−1. In the infrared absorption spectrum, the stretching vibration of C=O bond from the ester group at 1730 cm−1 and the stretching vibration of C–O–C at 1100 cm−1 were also observed [−1.The molecular structure of electrospun TPU nanofibers from DMF/THF and TCM/TFE solvent system was characterized by Fourier transform infrared spectrometer (FTIR), as shown in de bond) . It can observed . HoweverTCM/VTFE is 5/5. The tensile strengths were 3.08, 2.09, 1.01, 3.04 MPa for VTCM/VTFE = 8/2, 7/3, 5/5 and 4/6, respectively. With the increase of TFE in the solvent system, the Young’s modulus of electrospun TPU nanofibers  show excellent biocompatibility.D values b. This iTCM: VTFE = 8:2, 7:3, 5:5, 4:6. The concentration of TPU ranges from 0.5% to 8%. The obtained electrospun TPU nanofibers fabricated from this novel solvent system showed smooth morphology and uniform diameter distribution. The viscosity of the TPU solution increased with the increasing ratio of TFE in the solvent system. The Young’s modulus and tensile strength of the electrospun TPU nanofiber meshes first decreased and then increased. The maximum tensile strength of the electrospun TPU nanofiber first increased and then decreased. FTIR data showed that the chemical structure of the TPU was not affected by the TCM/TFE solvent system when compared to that of the DMF/THF solvent system. The TPU solution stability from the TCM/TFE solvent system was improved in contrast with the DMF/THF solvent system. The new solvent system can significantly improve the fiber tensile elongation ratio while maintaining the modulus and tensile strength. Electrospun TPU nanofiber meshes prepared using the novel TCM/TFE solvent system did not show cytotoxicity, which means the electrospun TPU meshes have excellent biocompatibility.A novel solvent system with TCM and TFE at different component ratios were developed for fabricating electrospun TPU nanofibers. The selected TCM and TFE component ratios are V