Fossil material in amber from Myanmar can provide important insights into mid-Cretaceous forest ecosystems. However, Myanmar amber has been receiving increased international attention due to reported links between amber mining and the ongoing humanitarian crisis in northern Myanmar, as well as the legal issues associated with its exportation. Here, we conduct a bibliometric analysis of Myanmar amber publications (1990–2021) and demonstrate how research interest in Myanmar amber is explicitly linked to major political, legal, and economic changes. An analysis of the authorship networks for publications on amber inclusions reveals how current research practices have excluded Myanmar researchers from the field. In addition, the international trade of Myanmar amber with fossil inclusions falls into a legal ‘grey-zone’ which continues to be exploited. This case study vividly demonstrates that systemic changes, alongside an increased awareness of inequitable research practices amongst the broader scientific and allied communities, are urgently needed to curb illegal practices in palaeontology. Myanmar amber collection and study in palaeontology is clouded with ethical and legal issues. Here, the history and legality of Myanmar amber use in the literature is reviewed. Amber, which is fossilised plant resin, of various geological ages can be found in several parts of the world, including the Baltic region of Europe, Alaska, Madagascar, Lebanon, the Dominican Republic, and Canada. Amber from Myanmar (formerly Burma) is particularly famous for preserving the remains of insects, plants, and reptiles that lived alongside the dinosaurs during the mid-Cretaceous, approximately 99 million years ago2. However, Myanmar amber has more recently gained international attention due to legal and ethical issues in the discovery, collection, trade, and research of this material5.Fossils entombed in amber provide exceptional and unique insights into the morphology and evolution of organisms that inhabited past forest ecosystems6. But by far the most popular fossil finds from the country are those in amber. Most amber is mined in the northern state of Kachin, with many fossils coming from the Hukawng Valley  and the Myanmar government military forces, the Tatmadaw, since the 1960s, only two decades after the country gained independence from British rule in 1948. Both the KIA and the Myanmar military have funded their activities through profits from the mining industry for decades, through both legal and illegal routes9. The most recent attempt by the military to seize control of the amber mining areas in Kachin State from the KIA occurred in 2017, and soon after, a UN Human Rights Council fact-finding mission reported on the violations of international human rights law and international humanitarian law perpetrated by the military in these areas10. These events have led recent media reports to describe working on Myanmar amber as an ‘ethical minefield’, and to question the ‘human cost’ of working on this material11.Myanmar has a rich palaeontological heritage, including fossils of the oldest representatives of anthropoid primatesley Fig. , though 12. More generally, this kind of legislation protects against extractive research practices, often referred to collectively as ‘parachute science’ , whereby researchers from higher income countries collect specimens or data from lower income countries without engaging with local researchers or communities15. While Myanmar has national laws and is a signatory of several international conventions that could apply to fossil material in amber  released a letter to editors of palaeontological journal editors, calling for a moratorium on publishing material in Myanmar amber, particularly that acquired after the military took control of the mines in 201714, in particular the links between amber mining in Kachin State and the documented human rights abuses by the military. In this study, we use bibliometric and affiliation data from the Web of Science to investigate temporal and geographic trends in Myanmar amber research over the last three decades (1990–2021) and explore how research output is related to national and international legal, commercial, and political developments. Through this investigation, we highlight the need for stronger systemic consideration of the ethical and legal concerns of working on this material, and palaeontological material from other conflict zones around the world.Numerous publications on spectacularly preserved fossils in Myanmar amber enter the scientific literature each year, and the vast majority of these do not consider the ethical implications of studying this materialBox 1 Legal DocumentsInternational Treaties◦Convention for the Protection of Cultural Property in the Event of Armed Conflict , 249 UNTS 215.◦Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property , 823 UNTS 231.◦UNIDROIT Convention on Stolen or Illegally Exported Cultural Objects , 2421 UNTS 457.Domestic Legislation◦The Myanmar Gemstone Law 1995 (The State Law and Order Restoration Council Law No. 8/95)◦The Myanmar Gemstone Law 2019 (Pyidaungsu Hluttaw Law No. 4/2019)◦The Antiquities Act 1957◦The Protection and Preservation of Antique Objects Law 2015 (Pyidaungsu Hluttaw Law No. 43/2015)slope = 0.55), with a peak observed around 2005. This changed after the year 2014 when the number of publications started rapidly increasing (slope = 24.8), reaching its highest value in 2020, with a total of 175 recorded publications in that year alone.Over the past three decades, the number of publications on fossil material in Myanmar amber recorded by Web of Science has increased Fig. . A break25. We observed two breakpoints in the non-amber time series, at the years 2004 and 2016  until 2004 when the number of publications starts to decrease at a similar rate (slope = −0.35) as the previous period . Finally, we see an increase in the number of publications post-2016 (slope = 1.03). In general, the number of non-amber fossils publications remained quite low, especially when compared with counts of amber fossil publications over the same interval. Note that these identified breakpoints should be taken in the context of the low overall amount of data in this time series.As a comparison, we examined the temporal trends in publications on non-amber fossils from Myanmar, such as Cenozoic primates and petrified woodn = 18), Myanmar (n = 17) and the US (n = 16) are comparable. The number of amber publications post-2014 was 35 times higher than the number of non-amber publications, whereas pre-2014, they were only 5 times higher than non-amber ones. In general, the number of amber publications per country (based on author affiliations) was significantly higher  than non-amber publications even after correcting for the expected difference between amber fossils and other fossils (standardised according to the period 2004–2015). No difference between amber and non-amber publications was observed before 2014 .Most of the research on fossils from Myanmar (~95%) is based on specimens in amber Fig. , with Chn = 69) and held the most important position and influence when it came to collaborations, with mostly in-country collaborations occurring during that time  with the US moving to third position  of publications containing a single author after 2014, compared to 36% (n = 43) before 2014.Examining the network of collaborations between authors on amber and non-amber publications, we identified the countries with most power and influence over research trends. Until 2014, researchers from the US led in terms of first-authored amber publications  were more prevalent before 2014, with an average of 63% of collaborations being among researchers from the same country, compared with 46% after 2014. Other countries besides China and the US, such as Germany, Russia and Poland, also significantly contributed to amber research post-2014 . After a ceasefire agreement with the Tatmadaw (Myanmar armed forces), most mining areas in Kachin State were nationalised and placed under the control of the state-owned Myanmar Gem Enterprise, which regulated mining activity and issued mining licences27. In 1995, new legislation exclusively for gemstones, including amber, was introduced, allowing their extraction and marketisation . As the fighting between the KIA and the Tatmadaw worsened in the lead up to the 2017 military offensive33, the KIA was forced away from the jade and gold mines that they controlled, meaning revenues from amber became even more important.In the late 2000s and early 2010s, trade with China began to gain momentum, and at the same time, Chinese amber mines tapped out27. Once in Tengchong, amber can be legally sold on the Chinese market and is subject to state regulations there. Amber can also be bought from the city of Myitkyina in Myanmar  did not surpass the 2020 total (n = 175)  also does not seem set to surpass the 2021 total. This might indicate the beginning of a change in publishing trends and a diminished interest in Myanmar amber research, perhaps due to increased scrutiny from the palaeontological community. This could also be a result of knock-on effects from the COVID-19 pandemic, which has impacted the scientific publishing process and restricted international travel, particularly travel to museums, other research institutions, and field sites.The total number of publications on Myanmar amber published in 2021 , has been the focus of several field efforts in the last century. The first fossils were collected in 1914, but no further work occurred until the late 1990s37. Given the attention that such fossils from Myanmar and other Asian regions were getting at the time, the government organised a fieldwork expedition to the Podaung Formation in 1997, aiming to “enhance the stature of the country”38. In the following years, joint fieldwork expeditions took place between Myanmar research teams and teams from the US, Japan, and France. Many of these international collaborations persist to this day, resulting in several publications over the years (e.g39.). Critically, we found that many of these publications on primate (i.e. non-amber) fossils include researchers from Myanmar as co-authors, which is in stark contrast to amber publications that rarely indicate collaborations with local researchers , an institution which also sells amber specimens. The other discusses the issue of parachute science with respect to Myanmar amber research, written by two authors of this study5. What we observed here is an extreme form of parachute science where instead of fieldwork, amber specimens are obtained through commercial routes and are apparently not regulated accordingly by national laws relating to fossils or gemstones (Table 14.Only five out of 872 (0.06%) publications on Myanmar amber in our dataset include researchers based in Myanmar as co-authors Fig. . For thres Table . As such16, suggesting that it insufficiently implements the UNESCO Convention which not only requires adopting export restrictions on cultural objects (Art. 6(b)) but also the imposition of penalties or administrative sanctions on individuals violating those restrictions (Art. 8). However, the current Myanmar amber economy also strongly relies on China who also is a party to the 1970 UNESCO Convention and the 1995 UNIDROIT Convention  publications released since this date (i.e June 2020–June 2022) refer in any way to legal or ethical issues associated with the material they describe  in Kachin State by groups affiliated with the military has intensified since the coup in early 2021, which has led the UN to suspend climate work with the Myanmar government45. As of August 2021, the state of emergency declared following this year’s military coup is set to remain in place until at least August 202346.Numerous recent media reports have described Myanmar amber as an ‘ethical minefield’ and note the ‘human cost’ of working on this material47. Given that most of the trade in these specimens occurs within a shadow economy where revenues go largely undeclared27, it would indeed be difficult to estimate the true revenue that the military or other parties receive. However, it is indisputable that amber is a significant source of income for the military32, and that fossil finds have directly influenced the increase in amber trade32 . These include specific guidelines on the considerations researchers should take when preparing and reviewing manuscripts, including ensuring that appropriate documentation is available to attest to the provenance of amber specimens. It is yet to be seen whether these guidelines will be adopted widely by researchers aiming to carry out research on amber or by journals catering for such research. In addition, SVP revised the 2020 moratorium on specimens acquired post-2017; instead, authors are now recommended to provide documentation for the legal and ethical acquisition of their amber specimens. At the same time, SVP also called for a moratorium for any amber material acquired after the military coup, which began in February 2021 and is still ongoing at the time of writing.In February 2022, SVP released guidance documents on carrying out research and publishing on amber material for researchers, research institutions, and journals, their editors and peer reviewers  of acquiring amber specimens, local researchers are excluded from working on these specimens themselves, despite them originating from their home country . In fact, the authorship for this paper was established through cold emailing, and the entirety of the communication for this research collaboration was conducted virtually.The most ethical and equitable research projects feature input from all involved parties, both local and foreign, in order to develop research agendas that are built on mutual respect and the needs and interests of local peoplery Figs.  and 4. T50 that lists the basic principles for acquisition of any material and the need for due diligence. Raising awareness about and supporting the fight against illicit trafficking of cultural material is one of ICOM’s highest priorities and by extension, that of its members. Museums can also assist in the establishment of local repositories in Myanmar, facilitate access and sharing of material, and provide training to Myanmar-based researchers and students.Museums can also play a part in paving the way towards more ethical research on Myanmar amber. Many museums, particularly in the US and Europe, already house large collections of Myanmar amber specimens. Museums that are part of the International Council of Museums (ICOM) should adhere to the ICOM Code of Ethics for Museums14. Additionally, funders, societies, editors, and peer reviewers must remain vigilant about ethical and legal issues in palaeontology to avoid perpetuating exploitative research practices (‘parachute science’). Palaeontology, and the geosciences more broadly, are currently grappling with overdue conversations around the societal and economic impact of their research practices, and action is urgently required. No matter how tenable the link between the scientific work and reported violations, our understanding of ancient life and its evolution should never come at the expense of human rights and human lives.The case of fossil material in Myanmar amber is a clear example of exploitative (or ‘extractive’) research in palaeontology, centred around the principles of ‘parachute science’ and scientific colonialism. Our findings document a direct link between research output and political, legal, and economic changes happening within the country. The situation surrounding Myanmar amber is complex and ever-evolving, but nonetheless shows how scientific research does not happen in a vacuum, and is regularly impacted by several interconnected external factors. For the field of palaeontology, this case highlights the importance of conducting and promoting ethical, equitable, and sustainable research practices that centre the needs and interests of local communities. Researchers must also take time to become familiar with the regulatory and cultural landscape of the location where they intend to conduct field research to avoid conduct that is unethical and/or illegal. International collaborations should always include local researchers, who can provide unparalleled expertise and insights, even beyond scientific knowledge52. Publications on Myanmar amber  and Myanmar fossils that are not encased in amber  were queried separately using specific keywords and filtered for categories pertaining to palaeontology 54. The initial values were obtained based on a visual inspection of the time series as well as the Davies test55. The Davies test is an independent test which verifies whether a non-constant regression parameter exists in a linear prediction, i.e. whether there is a significant change in slope between k number of points. The Davies test was repeated on identified segmented regressions until no more breakpoints were statistically deemed to be present. The Davies test also returns the best estimate among the k points, which was then fed into the segmented function which calculates the actual breakpoint using a maximum likelihood algorithm. After this analysis, the study period was divided into the identified segmented periods based on the detected breakpoints. These breakpoints were then compared to changes that occurred in the economic and political situation in Myanmar to identify probable causes for the shifts observed in the palaeontological research landscape.We calculated a 3-year rolling mean of the number of both amber and non-amber publications during the period 1990–2021 to take into account the publication process from acquiring the material to carrying out the analyses to publication in a peer-reviewed journal. The 2022 datapoint was omitted as it only represents the number of publications for half of the year of 2022. A segmented regression with breakpoints analysis was performed on the time series of mean number of publications to identify the years where the temporal patterns in publication significantly changed using the R package Because non-amber fossils are without any doubt subject to legislation with regards to collection and export, we consider non-amber publications to be the control group that represents how these materials would be researched if the special circumstances under which amber material fall under would not exist. Given the disproportionate amount of amber publications to non-amber publications (likely a results of the increased availability of amber specimens), we standardised the number of amber publications according to a ratio of amber vs non-amber publications calculated over a certain period of time, identified by the segmented regression analysis. We then compared the standardised number of amber publications to the number of non-amber publications using a Wilcoxon signed-rank test.56.We also investigated the influence that certain countries hold over others when it comes to collaborating on publications about Myanmar amber during the segmented periods identified by the breakpoint analysis. We consider lead authorship to be a representation of influence in this particular study as usually for any publication, the lead author  has the most responsibility and power over the line of research within the scope of the publication. As such we looked only at collaborations between the first author and the co-authors on a publication to identify the nature of the relationship between the countries of these authors. A country (country A) is considered to be hold more influence over another country (country B) when the number of publications led by researchers from country A is greater than the number of publications led by country B. We also constructed an undirected collaborative network using all affiliate countries regardless of their position on the authorship list to identify important actors within the network. We use centrality measures such as betweenness centrality and degree centrality as indicators of power. We also looked at whether more in-country collaborations occurred than between countries. Finally, we examined if there were certain countries that stood out in terms of number of leading publications through outlier detection using box plots as per Tukey’s methodFurther information on research design is available in the Supplementary InformationReporting Summary


Self-medication refers to the consumption of drugs such as antibiotics by individuals based on their own experience and knowledge, without consulting a doctor either for diagnosis or prescription. The inappropriate use of antibiotics is the primary source of antibiotic resistance (AR) development in microorganisms. As a result, some specific types of microorganisms that are naturally resistant to antibiotics have become considerably more common. Self-medication poses a danger to the advantages of antibiotics since it results in financial burdens on low and middle-income countries (LMICs), management failures, the evolution of antibiotic-resistant bacterial serotypes, and a higher risk of contamination of the general population by such tensions. Antibiotic misuse puts patients at risk for adverse drug reactions, false symptom relief, and the rise of drug-resistant microorganisms. It carries many health risks, chiefly in LMICs. These risks are linked to various factors, including a shortage of medical experts, low-level healthcare facilities, unregulated medication delivery, and negative public perceptions of doctors. The primary issue with self-medication is that majority of the population is uninformed of the harmful consequences of antibiotic resistance and how they might donate to it by self-diagnosing and self-treating with antibiotics. Antibiotic self-medication remains a common practice in society, and educational attainment significantly affects the frequency of this behavior. The article aims to educate the people by showing the development and plausible future to decrease antibiotic misuse. It also tells about the various challenges and prevention of this preceding problem. Most people believe bacteria to be microorganisms or pathogens causing trauma to their already ageing viscera. Antibiotics counter these bacteria and are the silver bullet solution to many medical problems. Without prescriptions, people also unknowingly consume antibiotics to counter "viral" diseases like cough, cold, and flu. Antibiotics are medicines against bacteria that kill or inhibit their growth and multiplication. They can be administrated through various routes of administration  . They caSelf-medication is diagnosing and prescribing drugs by an ordinary person without taking a physician's advice leading to the unnecessary expense of time and money, morbidities due to the adverse effects, and eventually, the development of antibiotic resistance (AR) by a reduction in the efficacy of antibiotics. It is a widespread practice all over the globe, especially in developing nations, and is seen as a substitute for those who are unable to afford the costs of healthcare amenities. The primary causes of self-medication include a shortage of medical supplies, long travel times to medical facilities, unfriendly attitudes of healthcare workers toward patients, and prior knowledge of the illness and its treatments. All these factors prevail in low and middle-income countries and add to the development of resistance . AntibioAntibioticsThe advent of antibiotics created an optimistic attitude toward fighting infectious diseases. The antibiotics work by showing various inhibition processes like inhibition of protein biosynthesis, inhibition of folic acid metabolism, and inhibition of DNA metabolism; some may also target bacterial cell wall synthesis . DevelopKeeping in mind the patient's pharmacokinetics and the dynamics of the drugs choosing and prescribing the most appropriate medication is the key to optimally treating the infections along with reduced adverse effects and fewer chances of developing antibiotic resistance . IndividAntibiotic resistanceOne of the many causes of the emergence of antibiotic resistance is an interruption in the ongoing medical treatment of a disease. This could be because people tend to forget their dosage and drug consumption when they start to feel better after their symptoms subside. The bacteria have become more resistant due to this inadequate treatment in terms of dose and duration . The regBroad-spectrum antibiotics are widely and unnecessarily utilized in healthcare settings due to the absence of early identification of pathogenic bacteria and their antimicrobial sensitivity patterns in patients with bacteremia and other severe diseases . AntibioThe public health sector faces a global challenge in developing strategies to prevent and fight the emergence of antibiotic resistance. Globalization and growth in worldwide travel and trade both unavoidably produce opportunities for the quick transmission of hazardous diseases and make the issue of antibiotic resistance considerably more challenging to solve . Even thEpidemiology of antibiotic resistanceWorld Health Organization has estimated that 10 million deaths can occur by 2050, which could be attributed to an increase in AR . In addiIn high-middle-income countries like China, Brazil, South Africa, and Libya, antibiotic resistance is a public health crisis due to the evolution of modern medicine. Antibiotic resistance poses many threats, like the failure of the therapy, an increase in infectious diseases, population biology alterations, and bacterial evolution . Indian A study initiated amongst health experts showed that antibiotics are the second most common type of medicine used by self-medication, the first being analgesics . Self-meReasons for antibiotic misuseStudies found that people chose to self-medicate with antibiotics for the following reasons: extra cost suffered from facility custodies; presumed information on antibiotics use extensive waiting stretch required to refer to health care facilities; experience with similar signs or antibiotics; disease supposed as minor by the patient; instruction from friends or relatives; absence of time to refer; monetary limitation; impolite behavior of health workers; lack of self-assurance in the effectiveness of antibiotics; lack of confidence in the efficacy of antibiotics; experience with similar symptoms and a layman often cannot even acknowledge if the given medicine is antibiotic or not, contributing to confusions and negligence in completing the antibiotic therapy .The selling of antibiotics and medications on Schedule H without a valid prescription is prohibited by the Indian Drugs and Cosmetics Act. However, numerous studies in the nation have indicated a significant incidence of antibiotics being sold over the counter, leading to self-medicated behavior ,24. AddiAlong with self-medication, the other factors leading to antibiotic resistance are the unseemly interaction between drug dispensers and clients that leads to inappropriate dispensing of antibiotics, poor public health, the unauthorized buying of antibiotics, high occurrence of infectious diseases, less access to appropriate antibiotics, low-quality diagnostic tools and prophylactic treatment also encourages the use of antibiotics . FurtherPrevalence of self-medicationSelf-medication may help treat acute illnesses that do not need consultation from a doctor, or recurring disorders diagnosed previously during earlier consultations. When done responsibly, it may facilitate faster relief to the patient by providing prompt medication access. It can be a cost-effective option in settings of limited sources, particularly in LMICs. However, inappropriate self-medication subjects the patient to several risks and drawbacks like adverse drug reactions, development of antibiotic resistance, masking of a more severe underlying condition and failure to consult a doctor in time . It is sConsequences of antibiotic misuse Self-medication results in antibiotic misuse, which has many consequences like adverse drug reactions, drug interactions, increased morbidity and mortality, and the emergence of AR . It decrPeople who do not obtain appropriate treatment on time are at an increased risk for a more severe course of the disease or a fatal outcome. Additionally, these patients remain communicable for extended periods, increasing the probability of transmission of resistant microorganisms if infection prevention measures are not executed . In a stPrevention of antibiotic misuseMethods of prevention include providing health education which will help to draw attention to the issues caused by antibiotic self-medication, especially among graduates and professionals. These issues involve using a doctor's previous prescription to obtain antibiotics, treating minor illnesses like a sore throat with antibiotics, switching antibiotics during self-medication, and stopping antibiotics when symptoms go away. In order to educate and spread awareness, specific campaigns to inform the public about various conditions and the value of seeking medical care from hospitals can be organized by the state and central governments.Specific other ways by which populations can overcome self-medication practices include availing medical supplies and personnel in public facilities-also and constructing more medical facilities close to communities to cut down on travel time to access health care. Healthcare professionals must modify how they view patients . They shThe issue of unused antibiotics can be resolved in the following ways: monitor and regulate doctors' prescribing practices to prevent overprescribing; instruct patients to administer antibiotics exactly as given through effective health education programs; forbid the sale of antibiotics without a prescription in pharmacies, and encourage patients to discard unused antibiotics . AvoidinExamining and considering patients' modified consultation behavior and other behavioral components should be one way to aim in future campaigns. These could include delayed prescription of antibiotics. Shortening the course of antibiotics prescribed to three to five days will axiomatically reduce the use of leftover antibiotics. Educated people can be given a message of not reusing antibiotics without proper diagnosis and knowing the disease completely . Even ifChallenges faced in the prevention of antibiotic resistanceIt is crucial to inform people regarding the development of antibiotic resistance in microorganisms and the limited management options available for infections related to drug resistance to prevent it from becoming an even bigger global crisis. The emerging problem of antibiotic resistance is not only a worry for the healthcare sector; if it is not contained, it could potentially harm a nation's ability to grow economically .The pharmaceutical industry must also overcome the dearth of new antibiotics being developed to treat bacterial infections. The growing crisis of antibiotic resistance and the threat of bacterial infections becoming fatal once more place the effectiveness of presently accessible antibiotic drugs in grave jeopardy. Lack of economic encouragement for research and strict supervisory requirements are two of the most important reasons why new drugs to treat bacterial infections with high case fatality rates have not been discovered .There are components in the healthcare system on both the supply and demand sides that contribute to the massive levels of antibiotic overuse for self-limiting infections. Due to healthcare providers' supply-side financial dependence on prescription sales, hospitals and community health centers unavoidably overprescribe antibiotics. The pharmaceutical industry is also considered a supply-side actor in the issue of antibiotic misuse. Most antibiotics are used outside hospitals worldwide, and access to antibiotics without a prescription is relatively frequent ,50. The Self-medication is increasing at an alarming rate globally, particularly in LMICs, and is the primary cause of the development of antibiotic resistance in microorganisms. Different factors contribute to the practice of self-medication, like partial knowledge of antibiotics, easy availability of antibiotics, quick relief from acute illnesses, and ignorance regarding the severity of the disease. There is a need to educate the general population about the inappropriate administration of antibiotics, such as using them for minor illnesses like sore throat, interrupting the treatment when symptoms subside, and switching antibiotics without consulting a doctor. The evolution in AR that occurred over time is the primary reason for the increased frequency with which initial regimens of choice for treating common diseases are modified. Thus, the emerging AR crisis is not only a concern for the healthcare industry since it could also affect a country's economic growth if not controlled.


Apis florea and its ectoparasite Euvarroa sinhai since they invaded Taiwan. Using a reverse transcription-PCR with specific primers enabled us to ascertain that DWV type A was prevalent among A. florea samples. Homology analysis and maximum-likelihood phylogenetic tree between different genotypes disclosed a complete polyprotein nucleotide sequence identity of 88% between isolates from A. florea, E. sinhai, and DWV type A strains from GenBank. The results demonstrated that a novel variant of deformed wing viruses exists in the invasive species A. florea and E. sinhai.The deformed wing virus (DWV) has been detected in Apis florea in Taiwan was first recorded in 2017. The deformed wing virus (DWV) has been identified as a common bee virus in apiculture around the world. Ectoparasitic mites are the main DWV vector for horizontal transmission. However, there are few studies about the ectoparasitic mite of Euvarroa sinhai, which has been found in A. florea. In this study, the prevalence of DWV among four hosts, including A. florea, Apis mellifera, E. sinhai, and Varroa destructor, was determined. The results showed that a high DWV-A prevalence rate in A. florea, ranging from 69.2% to 94.4%, was detected. Additionally, the genome of DWV isolates was sequenced and subjected to phylogenetic analysis based on the complete polyprotein sequence. Furthermore, isolates from A. florea and E. sinhai both formed a monophyletic group for the DWV-A lineage, and the sequence identity was 88% between the isolates and DWV-A reference strains. As noted above, two isolates could be the novel DWV strain. It cannot be excluded that novel DWV strains could pose an indirect threat to sympatric species, such as A. mellifera and Apis cerana.The invasion of  Apis mellifera, thereby reducing the commercial values of honeybee pollination and products [Iflavirus virus in the family of Iflaviridae, which can prolong its life cycle through mass replication via honeybee pupae and adults or the ectoparasitic mite Varroa destructor [The deformed wing virus (DWV) has been studied extensively, as it is thought to cause colony losses in the Western honeybee products . It is astructor . Unsuccestructor , and evestructor .Kakugo virus (KV) and the so-called deformed wing virus (DWV); it has been recognized that it is highly adaptive to various hosts [V. destructor [Varroa destructor virus-1 (VDV-1). Subsequent studies have shown at least four variants to be detected in Varroa mites [Aethina tumida and stingless bee Melipona subnitida [The DWV has the characteristics of rapid replication and high mutation rate and often exists in the host and in an environment with multiple genotypes or so-called quasispecies . The genus hosts , whereasus hosts . DWV-B wstructor , as it woa mites ,10. The ubnitida ,12,13.The DWV genome length is about 10,140 nucleotides (nt) with a poly (A) tail, and 30 nm particle geometry is in icosahedral symmetry ,14. The A. florea is an invasive alien species (IAS)   that hasa sinhai  in A. flulations ,22,23,24with DWV . To datey traits . These my traits ,28. In ay traits ,31,32,33n Taiwan , where mn reared ,30,31. TA. florea located in the Fengshan, Gangshan, Gushan, Lingya, Qianzhen, Qijin, and Xiaogang districts in Kaohsiung city were reported by Hsu et al. [A. florea were collected periodically in these areas, and between four and eight adult workers in each nest were sampled for monitoring DWV-A and DWV-B. In addition, sympatric A. florea and A. mellifera foragers were collected by sweeping nets periodically in the open spaces of these areas  . SummariA. mellifera sample from the apiary of NCYU as a positive control.Sample RNA was used to synthesize cDNA with an oligo (dT) 18 primer  by a HiScript I TM First Strand cDNA Synthesis Kit . PCR reactions were performed in a 25 µL mixed solution using a 2× red PCR Master mix kit (Ampliqon). For DWV-A and DWV-B, the three primers used to sequence the RdRp-encoding region were DWV-F (GGATGTTATCTCTTGCGTGGA), DWV-R (CGATAATAATTTCGAACGCTGA) (412 bp) ; KV-F . The transformants (E. coli) were selected by blue-white selection on the plates containing 5% X-gal (20 mg/mL), Ampicillin (100 μg/mL), and IPTG (50 Mm)) and were screened as positive clones by colony PCR. The plasmid was isolated and then restricted the enzyme digestion of plasmid DNAs with EcoR1. For each virus, 3–5 clones were picked up for Sanger sequencing. The cDNA clones were reamplified from the respective plasmid with a pair of T7P and SP6 by automated DNA sequencer at Genomics BioSci & Tech Co., Ltd. Company . All the sequences were submitted to GenBank (accession nos. OP889266–OP889269).PCR reactions used a Q5 High-Fidelity DNA Polymerase Kit  and 10 mM dNTPs. Each reaction contained a 5x Q5 buffer, 2.5 mM dNTPs, Q5 high-fidelity DNA polymerase, forward and reverse DWV-variant-specific primer , diH2O, Based on the complete polyproteins to construct a homology tree and phylogenetic tree, the phylogenetic relationships among the strains of the honeybee viruses and other close groups available in GenBank were initially assessed using BLAST . The ideA. florea, A. mellifera, and E. sinhai  were in open-space samples (A. mellifera showed a lower portion of positive results (32.1%), all samples from E. sinhai and V. destructor were positive for KV.All samples containing DWV were amplified by the PCR using the primers KV-F/-R and DWV-F/-R, and it was confirmed by gel electrophoresis that the KV primer showed higher sensitivity than DWV in . sinhai ; Table 3 samples . Though A. florea (AF01T243 (AF01), accession nos. OP889266), A. mellifera (AM01TGS8 (AM01), accession nos. OP889268), E. sinhai (ES01TFS11 (ES01), accession nos. OP889267), and V. destructor (VD01Tvd1 (VD01), accession nos. OP889269) in this study, along with the previously reported DWV isolates , A. mellifera (AM01), E. sinhai (ES01), and V. destructor (VD01) in this study, along with the previously reported DWV isolates  The ORF is predicted to encode a 2896 aa polyprotein. (2) 950 aa capsid proteins; (3) 713 aa 3C + RdRp; (4) 472 aa helicase; (5) 211 aa leader protein; (6) 320 nt 3′ UTR (without poly-A); and (7) 1135 nt 5′ UTR. Homology analyses performed by nucleotides and amino acids of 3′ UTR, 5′ UTR, the polyprotein, VP1-4 of the capsid protein , the leader protein of structural polyprotein, helicase, 3-chymotrypsin-like protease, and the 3-chymotrypsin-like protease (3C + RdRp) region were referred to the complete DWV-A genome sequence (AJ489744.2). Here, we only describe the nucleotide identity in each region of the DWV genome. The findings of the complete nucleotide (nt) and amino acid (aa) sequence identities are in alignment with AF01, and the corresponding regions of the four isolates , DWV-B (AY251269.2) and DWV-C (CEND01000001.1)) was shown , species of the Iflaviridae are demarcated by amino acid identity in the sequence of the capsid proteins (CPs) when the strains of a species are above 90% [A. florea (AF01T243), E. sinhai (ES01TFS11), and the DWV-A strain (AJ489744.2) with regard to the CPs; therefore, we conclude that two virus isolates exist in the new variant of DWV. In addition, the phylogenetic comparison of DWV from various species in this study suggests that there are at least three distinct main groups within the DWV quasispecies. DWV isolates found in Taiwan were clustered within the DWV-A clade. Each one of the isolates from A. florea and E. sinhai in this study formed a monophyletic subgroup with other strains of the DWV-A, and the similarity of the two isolates was only 89% with DWV-A sequences. The 3C-pro and RdRp regions of the DWV genome from A. florea and E. sinhai tend to be highly conserved among the RNA viruses [In this study, we emphasized only the prevalence and variants of DWV in the invasive honeybee ispecies ,14,17,40bove 90% . In ligh viruses . Therefo viruses ,43,44. IA. florea and E. sinhai, the sequence similarity in the helicase coding regions was the lowest (93.5%). According to previous studies, helicase is the most highly conserved region and key recombinant hotspot of DWV genomes, but whether there is a recombination between isolates in the helicase region needs to be further explored [A. florea and E. sinhai. As a result of all the above results combined, it was found that there was still genetic variation between the two isolates and DWV-A isolates. We have evidence that the isolates from A. florea and E. sinhai are both new variants of DWV. In fact, at least a slight sequence difference in the genome, or the substitution of a few amino acids, is enough to produce different toxicities in certain types of viruses [A. florea without apparent symptoms and in E. sinhai samples. It can also be observed that the nucleotide and amino acid sequences between the A. florea and E. sinhai DWV isolates were highly identical. From the above result, we can determine the pathogenic correlation between mites and honeybees, but there is not yet strong enough evidence of which is the original virus carrier. Previous studies have indicated that A. florea and A. mellifera have been found to prey on honey sources from hives, and on top of that, A. florea carries the ectoparasitic mite E. sinhai and has also been shown to survive on A. mellifera and A. cerana [E. sinhai has been found in the nests of A. mellifera [A. florea and E. sinhai. The V. destructor, which was originally transferred from A. cerana to A. mellifera, contributed to a significant increase in the prevalence of DWV in the honeybee colony, a decrease in the diversity of the deformed wing virus, and the dominance of a single DWV genotype [Turning to the experimental result on the sequence homology between the isolate from explored ,35. Spec viruses . In the . cerana ,46. In Tgenotype .A. florea and its acquired mite E. sinhai are invasive species in Taiwan and several other countries [Euvarroa mites on honeybees. The life cycle and feeding behavior of E. sinhai are ecologically similar to the V. destructor [E. sinhai is concerned, it may be a dominant pathogen transmitter and lead to a chain reaction of cross-infection in the overlapping niches of sympatric honeybee species, which indirectly affects the evolution of the virus [Tropilaelaps mercedesae and V. destructor [A. mellifera and A. florea [The presence of different species of bees and their associated parasitic mites in sympatric areas may facilitate the exchange of parasites between them and the simultaneous infestation of multiple mites at the population or individual level ,49. The ountries ,51, and structor . As far he virus ,53,54, sstructor ,56.To su. florea , and secA. florea and its ectoparasitic mite E. sinhai. Moreover, mites might be a biological vector and open up new avenues of inter-taxa virus transmission. Future research should consider the potential effects of new virus strains more carefully, and it should be investigated whether it has become a new variant of the deformed wing virus so as to establish the invasion risk level of the invasive A. florea and avoid endangering the apiculture of Taiwan and the world.Our data indicate that the new virus variants are suspected to be carried by invasive


Porous concrete has recently gained increasing attention in the construction industry. To improve the properties of porous concrete, coal bottom ash (CBA) was used as the aggregate in the concrete mixtures studied herein. Hybrid CBA aggregates, including a 20% proportion of particles with sizes of 1.2~2.5 mm and an 80% proportion of particles with sizes of 2.5~5.0 mm, were used in the mixtures. Various water/cement ratios ranging from 0.25 to 0.35 were used in the mixtures. The effects of compaction at 0.5, 1.5, and 3.0 MPa on the properties of the porous concrete were also examined. The increase in the water/cement ratio reduced the unit weight and thermal conductivity while increasing the porosity of the porous concrete. Although the compaction had a significant impact on the other properties of the porous concrete, the thermal property was not significantly influenced. By using CBA in porous concrete, the mechanical and thermal properties of the concrete were significantly improved. Finally, the relationships between the thermal conductivity and other properties of the porous concrete were investigated. Developing novel materials with multiple properties that benefit the environment and support sustainable development is a global trend. Among the novel materials, porous concrete has received increasing attention in the civil construction field because it exhibits a wide range of applications ,2,3. It The properties of porous concrete result from the volume of open or interconnected voids. Therefore, to improve these properties, the utilization of lightweight coarse aggregates, to which little or no sand is added, and an adequate amount of cement paste is recommended for porous concrete . ZaetangThe physical properties of porous concrete mainly depend on those of the cement paste and aggregates used, and thus, the water/cement ratio may also have an effect on the properties of the porous concrete. Huang et al.  conductePorous concrete contains only coarse aggregate or a small amount of fine aggregate and a low water-cement ratio, and thus the cement paste and aggregate act as the skeleton of the porous concrete. Therefore, the workability of porous concrete is lower than that of conventional concrete, and compaction of the concrete may be required to improve the adhesion between the cement paste and coarse aggregate.According to a study by Bonicelli et al. , compactThe addition of small amounts of fine aggregates to lightweight concrete significantly improved the mechanical properties of porous concrete . HoweverThis study was designed to investigate the effects of the water/cement ratio, and the compaction level on the thermal conductivities of hybrid CBA porous concretes made without sand. The unit weights, porosities, and thermal conductivities of the CBA porous concrete were investigated. In addition, the relationships between the thermal conductivity and the physical properties of the CBA porous concrete were analyzed.The full-scale experiment used in this study is illustrated in 3. For the oven-dried state, the hybrid CBA presented a lower density of 1.61 g/cm3. The table also shows that water absorption by the hybrid CBA was very high, with a value of 7.75%.The CBA used in the mixtures was a hybrid aggregate with two types of CBA with different particle sizes. The hybrid aggregate included an 80/20 volume percent ratio of CBA with a size range of 2.5–5.0 mm and CBA with a size range of 1.2–2.5 mm. The CBA was obtained from a thermal power plant company named Korea South-East Power Co., Ltd., located in Yeongheung, Korea. These large original CBAs were ground with a ball mill to obtain the desired sizes. In this study, fine aggregates were not included in the mixtures because the addition of fine aggregates reduced the porosity, drainability, and thermal isolation properties of the porous concrete . To achi3 and 3650 cm2/g, respectively. The cement used in the mixtures was ordinary Portland cement type I (OPC), which was provided by the Ssangyong C&E Company located in Jung–gu, Seoul, Korea. The density and the fineness modulus of OPC were 2.23 g/cm2 (55.75%) and Al2O3 (26.15%). It was reported that the high amounts of these components improved the pozzolanic reaction of the concrete.Nine mixtures were prepared to investigate the effects of the water/cement ratio and compaction on the thermal conductivities of the CBA porous concrete. The details for each mixture are shown in Due to its high-water absorption capacity, the hybrid CBA was prepared under SSD conditions to provide the water needed for hydration. In addition, a cohesive agent was added to the mixtures to improve the adhesion between the aggregate particles.Porous concrete is less consolidated than other concrete because it does not contain sand, which results in a porous structure for the concrete. Therefore, compaction is necessary to enhance the adhesion between the aggregates in porous concrete. In this study, special molds with thicknesses of 10 mm were prepared to secure the shapes of concrete specimens during the compaction loading. The porous concrete was cast in a steel cylindrical mold with dimensions of 100 mm (diameter) × 230 mm (height).The schematic compaction and steel cylindrical mold are shown in After 24 h of casting, the concrete specimen was demolded and then cured in a water tank at 24 ± 2 °C for 28 days in accordance with KS F 2405 .The unit weights, porosities, and thermal conductivities of the CBA porous concrete samples were measured in this study. The unit weight and porosity of the porous concrete were measured with cylindrical specimens, which were in accordance with Korean Standard KS F 2405 .To evaluate the unit weight of the porous concrete, the lengths and diameters of three cylindrical specimens were carefully measured, and then each porous specimen was weighed. Finally, the unit weight of the porous concrete was calculated.wM) and in the dry state (dM) were obtained. The wM value was measured when the cylindrical specimen was totally immersed in the water. Due to the buoyant force in the water, the wM value is lower than the dM value. For the dry condition, the porous specimens were dried at 105 ± 5 °C for 24 h. Finally, the total void ratios of the porous specimens were determined as follows:tV is the total void ratio, V is the volume of the cylindrical specimen. The reduced weight of the specimen in the water is equivalent to the weight of the water displaced by the CBA. Therefore, the total void ratios can be calculated by using the above equation.To determine the porosity characteristics of the CBA porous concrete, the total void ratio of the concrete was analyzed. The masses of the porous concrete specimen in water (T(t) near the hot disk’s surface, and the nondimensional function of time D(t) was recognized. Then, a linear relationship between T(t) and D(t) was estimated, and the slope of this line determined the thermal conductivity, k, of the CBA porous concrete [The thermal conductivity of the porous concrete was estimated according to ASTM D 5334-05  by applyIt is known that the thermal conductivity of concrete is strongly affected by the moisture content and the coarse aggregate in the concrete ,35,36. A3 to 1165 kg/m3 when the water/cement ratio was increased from 0.25 to 0.3. The same tendency was also observed for the C1.5 series; the unit weight of the C1.5 series decreased by 4.1% with the increasing water/cement ratio. Similarly, the unit weight of the C3.0 series decreased slightly, by 2.7%, with increases in the water/cement ratio. Accordingly, the unit weight of the CBA porous concrete was insignificantly affected by the water/cement ratio.The influence of the water/cement ratio on the unit weight of the porous concrete is illustrated in The porosity of porous concrete mainly depends on the aggregate particle size and aggregate type because there is just enough cement paste volume to cover the aggregate particles, and it cannot fill the voids between aggregates. Therefore, the water/cement ratio did not significantly affect the unit weight of the porous concrete. A similar tendency was also revealed by Costa et al. . In theit test analysis between the two results was conducted. The analysis results showed that the valuet of the two test results was 2.55, which was greater than the αt value of 2.15 from the Student’s t table. This result concluded that the two results were significantly different, and the compaction level affected the two series. Similarly, the unit weight of the C3.0-W35 specimen was greater than those of the C0.5-W35 and C1.5-W35 specimens. This was because the application of the compaction to the concrete specimens reduced the void content in the CBA porous concrete, and thus, the unit weight of the concrete increased, as presented in the test results.3. Meanwhile, the unit weight of the CBA porous concrete in this study was in the range of 1150~1400 kg/m3, which indicates that the unit weight of the porous concrete was significantly reduced with the inclusion of CBA.Compared to the normal porous concrete, the CBA porous concrete showed a lower unit weight. Banevičiene et al.  cast norThe total void ratios observed for various water/cement ratios and compaction levels are presented in For the C0.5 series of specimens, the total void ratio increased slightly from 30.6% to 31.9% when the water/cement ratio was increased from 0.25 to 0.35. However, for the C1.5 series, the total void ratio exhibited an increasing tendency with increases in the water-cement ratio. Specifically, the total void ratio increased significantly by 7.0% and 16.1% when the water/cement ratio was increased from 0.25 to 0.30 and 0.35, respectively. Additionally, for the C3.0 series, the total void ratios of the C3.0-W25, C3.0-W30, and C3.0-W35 specimens were 19.3%, 21.0%, and 23.2%, respectively.Therefore, the test results showed that the total void ratios of the CBA porous concretes increased slightly with increases in the water/cement ratio. It could be assumed that an increase in the water/cement ratio in the mixture generated voids in the interface transition zone, which resulted in increases in the porosities of the porous concrete . In a prThe influence of the compaction on the total void ratio can be found in t test analysis between the C0.5-W30 and C1.5-W30 series was performed. The valuet between the two series was 2.85, which was higher than the αt of 2.18 from the Student’s t table. This indicates that there was a statistically significant difference between the C0.5-W30 and C1.5-W30 series and that the compaction levels influenced the two mixtures. In addition, for a water/cement ratio of 0.35, the total void ratio of the specimen with a compaction of 3.0 MPa (C3.0-W35 specimen) was 37.3% and 25.0% lower than those of the C0.5-W35 and C1.5-W35 specimens, respectively.The total void ratio of the concrete specimen made with a compaction level of 3.0 MPa (C3.0 series) was always lower than those of concrete specimens treated with compaction levels of 0.5 (C0.5 series) and 1.5 MPa (C1.5 series), respectively. Specifically, for a water/cement ratio of 0.25, the total void ratio of the C3.0 specimen was 19.3%, which was 58.8% and 29.8% lower than those of the C0.5 and C1.5 specimens, respectively. Similarly, for a water/cement ratio of 0.30, the total void ratio of the specimen with a compaction of 3.0 MPa (C3.0-W30 specimen) was 27.6% and 49.5% lower than those of the C0.5-W30 and C1.5-W30 specimens, respectively. The standard deviation of the C0.5-W30 specimen was high, and thus, a Student’s It was also reported that compaction directly affected the microstructures in porous concrete . IncreasFinally, for the C3.0 series, the lowest thermal conductivity was also measured for the specimen with a water/cement ratio of 0.35 (C3.0-W35 specimen), while the C3.0-W25 and C3.0-W15 specimens showed greater values. It is known that the increase in the water/cement ratio results in higher capillary pores in cement paste at the hardening stage. In addition, the high water/cement ratio reduced the thickness of the cement paste coating the CBA, which led to an increase in the porosity of the CBA porous concrete. This phenomenon improved the thermal insulation of the CBA porous concrete.Additionally, the influence of the compaction on the thermal conductivity of porous concrete is shown in For specimens with a water/cement ratio of 0.25, the test results showed that the specimens made with the compaction levels of 0.5 MPa (specimen C0.5-W25) and 1.5 MPa (specimen C1.5-W25) exhibited similar thermal conductivities, but the thermal conductivity of the specimen subjected to a compaction level of 3.0 MPa (specimen C3.0-W25) was approximately 1.8% greater than that of specimen C0.5-W25. Among the specimens with a water/cement ratio of 0.30, specimen C3.0-W30 also showed the greatest thermal conductivity at 0.60 W/m∙K, which was 3.2% and 1.7% higher than those of specimens C0.5-W30 and C1.5-W30, respectively. Additionally, for specimens with a water/cement ratio of 0.35, the thermal conductivity of the specimen made with a compaction level of 3.0 MPa (C3.0-W35) was higher than that of any other specimen.Therefore, increases in the compaction level led to decreases in the porosity of the CBA porous concrete, which resulted in decreases in the thermal conductivity. Thermal conductivity and porosity are inversely proportional, which was reported previously by Chen et al. . In theiIn addition, the use of CBA as the coarse aggregate in porous concrete improved the thermal insulation characteristics. Compared to that of conventional porous concrete, the thermal conductivities of the CBA porous concrete showed lower values, while those of conventional porous concrete was in the range of 1.80–2.02 W/m∙K . TorkittThe surfaces of porous concrete specimens prepared with three different compaction levels are shown in In addition, to consider the effect of the compaction level at different positions along the depth of the specimen, scanning electron microscopy (SEM) analysis was performed. To obtain the examined pieces, the cylindrical specimen was cut in half. Then, three different pieces at different positions with dimensions of 20 mm × 20 mm × 10 mm were extracted from the half top of the cylindrical specimens, as shown in The relationship between the unit weight and the total void ratio is shown in U is the unit weight (kg/m3), and V is the total void ratio (%) of the CBA porous concrete. The coefficient of determination (R2) for this equation was close to one, which indicated that the equation could be used to predict the unit weight precisely by using the total void ratio of the porous concrete.As indicated by regression analysis, the relationship between the unit weight and the total void ratio under various compaction levels was expressed exponentially by the following equation:K is the thermal conductivity (W/m∙K), and U is the unit weight (kg/m3) of the porous concrete.The proposed equation relating the thermal conductivity of porous concrete to the unit weight is as follows:R2) for this equation was low because the measured values deviated from the regression line due to a lack of measurements. Accordingly, the accumulation of more measured data would increase the coefficient of determination.The coefficient of determination , and V is the total void ratio (%) of the porous concrete.Based on the test results of this study, the linear equation predicting the relationship of the thermal conductivity for porous concrete with the total void ratio is as follows:The plot of the thermal conductivity versus the total void ratio exhibited a low coefficient of determination, which was due to high variability in the test results. However, more measured data would likely increase the coefficient of determination and, thus, improve the accuracy of the prediction.The unit weight of CBA porous concrete was slightly affected by the water/cement ratio. An increase in the water/cement ratio from 0.25 to 0.35 led to decreases in the unit weight of the porous concrete ranging from 3.0 to 5.0%. Moreover, the compaction level significantly increased the unit weight of the CBA porous concrete by 5.0 to 15.0%. In addition, the statistical results indicated that the compaction levels had different influences on each mixture.The test results revealed that the total void ratio of the CBA porous concrete increased as the water/cement ratio increased, but this increase was not significant. However, the increases in the total void ratios of CBA porous concrete ranged between 7.0% and 17.0% with the increasing compaction level. It was also observed that the compaction dramatically reduced the porosity of the concrete. Statistical analysis was also carried out and revealed the statistically significant differences between the results.Regarding the effect of the water/cement ratio on the thermal conductivity of the CBA porous concrete, the thermal conductivity was significantly reduced by increases in the water/cement ratio. The thermal conductivity of the CBA porous concrete decreased by 4% to 16% as the water/cement ratio was increased from 0.25 to 0.35.The test results also revealed that the thermal conductivity of the CBA porous concrete decreased by 0.2% to 9.6% with increases in the compaction level. This implied that the thermal insulation of the CBA porous concrete was not significantly affected by the compaction levels used in this study, but the other properties were significantly improved.Finally, the relationships between the thermal conductivity and the mechanical properties of the porous concrete were estimated. By using the relationship curves, the tendency of thermal conductivity relating to the unit weight and total void ratios could be determined.The thermal conductivity of CBA porous concrete was investigated in this study. The effects of the water/cement ratio and compaction level on the unit weight, total void ratio, and thermal conductivity of CBA porous concrete were analyzed. In addition, statistical analysis was conducted to ensure a statistically significant difference between the results. Based on the extensive test results, the following conclusions can be drawn from this study:This study primarily focused on the thermal properties of CBA porous concrete. The experiment on the permeability and durability of the CBA concrete was out of the scope of the study. However, the permeability and durability of the CBA porous concrete will be investigated in future studies.


The test observed the failure mode of the specimen and obtained the stress–strain curve of the whole process of its force damage failure. An in-depth analysis of polypropylene fiber all-coral seawater concrete’s peak stress, peak strain, initial elastic modulus, axial deflection, energy dissipation, ductility, and damage evolution process was carried out based on the experimental data. The test findings indicated that the best effect on the deformation properties of polypropylene fiber all-coral seawater concrete is obtained when 3 kg·m−3 of polypropylene fiber is blended. Under triaxial compression, the correct number of polypropylene fibers may significantly enhance the peak stress, peak strain, ductility, and elastic modulus of polypropylene fiber all-coral seawater concrete, therefore enhancing the brittle characteristics of coral concrete. During the triaxial surround pressure test, the confining pressure value and polypropylene fiber coupling effect delayed the appearance of initial damage in polypropylene fiber complete coral seawater concrete specimens, slowed the development of damage, and reduced the degree of damage to the specimens.In order to study the mechanical properties of polypropylene fiber all-coral seawater concrete in triaxial compression, 36 specimens were developed and constructed for triaxial compression load testing employing confining pressure value  and polypropylene fiber admixture (1 kg·m In recent years, with the continuous depletion of land resources, the demand for the construction of oceanic islands and reefs has continued to increase. The construction of islands and reefs not only involves the issue of territorial integrity and sovereignty of countries, but also has significant importance in military and economic terms. However, traditional gravel aggregates and freshwater resources on the island are extremely limited, and transportation from the mainland is costly and time-consuming . Coral dSo far, scholars from various countries have achieved more fruitful results on the mechanical properties of coral concrete ,10,11. IFrom the above research results, it can be seen that there has been much research on the basic mechanics of polypropylene-fiber-reinforced concrete. However, there are very few studies on polypropylene-fiber-reinforced all-coral seawater concrete. Especially in engineering practice, most triaxial-force-bearing components–such as revetment, retaining walls, and other port engineering structures and wave-absorbing blocks–are subjected to complex stress states. Scholars have paid very little attention to its mechanical properties and damage and energy consumption processes. Therefore, this paper intends to carry out triaxial compressive tests of polypropylene fiber all-coral seawater concrete and carry out the ratio design of all-coral seawater concrete with different doses of polypropylene fiber. The effects of peritectic pressure value and fiber content on the peak stress, peak strain, elastic modulus, ductility, actual energy consumption, and damage development process of polypropylene fiber all-coral seawater concrete were analyzed in depth. Also put forward were the force mechanism and the functional relationship of each design parameter. At present, the research results of coral aggregate concrete basically focus on the strength level, or uniaxial compression test, and there is no in-depth discussion on the triaxial stress mechanism and stress performance of coral coarse aggregate concrete. This experiment was carried out for the first time in the world and has certain research significance. In this paper, the modifying effect of polypropylene fibers on the mechanical properties of all-coral seawater concrete under complex stress conditions is investigated. In order to provide reference for applications such as marine engineering island construction.The test materials included coarse coral aggregate, fine coral aggregate, seawater, ordinary Portland cement, polypropylene fiber, and water-reducing agent. Among them, coral aggregate is selected as coarse aggregate and coral sand as fine aggregate on an island in the South China Sea , as shown in −3, 2 kg·m−3, and 3 kg·m−3 were selected. Since the test was conducted using coral aggregates that were not prewetted, the feeding sequence shown in D = 100 mm and height H = 200 mm were designed and fabricated with the various parameters of confining pressure value wσ and polypropylene fiber dosing V. The ratio design of polypropylene fiber all-coral seawater concrete was referred to the “light aggregate concrete structure technical regulations” (JGJ 12-2006) [The ratio design is shown in 12-2006) . The desAll specimens were loaded using an RMT-201 rock mechanics and concrete mechanics testing machine following the specifications of Mechanical Properties Test Methods for Ordinary Concrete (GB/T 50081-2019) , and theWhen the specimen was loaded, it was initially prepressurized to the hydrostatic pressure condition shown in Gemini SEM 360 was used for microscopic observation, as shown in wσ = 0 MPa, the specimen was in a uniaxial compression state, one or more main cracks parallel to the loading direction existed on the surface at the time of damage, and the specimen was damaged by vertical splitting at the end of loading, as shown in wσ ≤ 6 MPa, the vertical development of cracks inside the whole coral concrete was restricted due to the constraint effect of the constraint pressure value. The main crack developed obliquely, and the specimen showed oblique splitting damage. The horizontal angle of the main crack was approximately 65°. With the increase in the restraint pressure value, the angle slightly decreased, and the width of the main crack gradually decreased. When the confining pressure reached 6 MPa ≤ wσ ≤ 12 MPa, the horizontal angle of the main crack continued to shrink to between 45° and 60°. At this time, due to the large deformation of the specimen, the confinement effect of the confining pressure value on the fine cracks began to weaken. It was observed that the specimen exhibited oblique shear failure, the oblique crack penetrated the specimen, and the crack developed from oblique to approximately horizontal, forming many horizontal cracks. The failure surface was primarily concentrated in the middle of the specimen. When the confining pressure value was 12 MPa ≤ wσ ≤ 18 MPa, the higher lateral restraint dramatically limited the development and penetration of vertical and oblique cracks, and the failure mode changed to transverse shear failure. There were no apparent cracks on the surface, the oblique prominent cracks on the surface of the specimen largely disappeared, and the grid-like cracks gradually increased. The stress peak point disappeared, and the peak of the curve was nearly horizontal. At the end of loading, the middle or end of the specimens with more dense grid-like cracks became thicker.When the confining pressure value V = 3 kg·m−3. During the test, at wσ = 0 MPa, the specimens that did not contain polypropylene fiber sustained severe, broad cracking and spalling damage. Some specimens even fragmented into many pieces. The sample containing polypropylene fiber broke but did not peel off. When the specimen’s compressive strength was attained, two symmetrical diagonal fractures occurred on the specimen’s surface for the whole coral concrete with fiber admixture V = 1 kg·m−3 and confining pressure value wσ = 0 MPa. In consequence, the specimen lost its axial-load-bearing ability and failed.The effect of polypropylene fiber on the damaged specimens was more evident when the confining pressure value was lower than 6 MPa, and the effect of polypropylene fiber on the destructive form gradually decreased as the confining pressure value increased. Among them, the minimum number of visible cracks on the surface of the specimen appeared with polypropylene fiber content wσ = 0 MPa, the specimen was in uniaxial compression. Its stress–strain curve experienced a rapid decrease in strength after the peak. This indicates that the all-coral seawater concrete has prominent brittle damage characteristics in the uniaxial compression state. Based on the analysis of 0MPa ≤ wσ ≤ 6 MPa, the slope of the ascending section of the stress–strain curve of the specimen increased with the increase in the restraint pressure value. The peak rose step by step, and the descending section gradually became flat. It indicates that a certain lateral restraint can block the interfacial bond damage and ensure the load-bearing and deformation capacity of polypropylene all-coral seawater concrete. When 6 MPa ≤ wσ ≤ 12 MPa, the peak of the stress–strain curve continued to increase, the peak of the curve tended to be horizontal, and the damage rate slowed down. The residual deformation of most specimens under this circumferential pressure was considerable, and they were undamaged after loading. When wσ = 18 MPa, the peak point of the stress–strain curve disappeared, and the curve continued to rise slowly after reaching the peak value. At the same time, a sizeable axial deformation occurred, indicating that the strength and deformation performance of the all-coral seawater concrete had been improved under the constraint of high confining pressure.V = 1 kg·m−3 to V = 3 kg·m−3.The peak stress decreased and then increased, and the peak strain increased and then decreased during the increase in polypropylene fiber addition from V = 0 kg·m−3 decreased rapidly. When the fiber content increased from V = 1 kg·m−3 to V = 2 kg·m−3, the polypropylene fibers started to participate in stopping cracking in the descending phase of the stress–strain curve as the cracks inside the specimen gradually expanded. The decreasing section of the stress–strain curve of the specimen gradually leveled off. The residual strength gradually increased, making the development of fine cracks in the cracking of all-coral seawater concrete delayed. When the fiber content was V = 2 kg·m−3 to V = 3 kg·m−3 due to the correct amount of polypropylene fiber in the full coral seawater concrete, specimens under load inhibited the development of small cracks to a certain extent. A high number of fibers in a certain amount of coral concrete could not be thoroughly dispersed. Clumped and knotted fibers formed weak interfaces in the all-coral seawater concrete. Cement slurry could not enter into the concrete, creating an internal stress concentration damage point, thus affecting the compressive strength.After the stress–strain curve experienced peak load, the strength of the specimen with fiber admixture vσ in the rising section of the stress–strain curve), as reported in Each group of specimens had characteristic point parameters such as yield, peak, stress–strain parameters at the damage point, and elastic modulus (secant modulus at 0.4 The structure of polypropylene fibers was observed by scanning electron microscopy (SEM), and the surface of polypropylene fibers was found to be smooth and in the form of long thin strips, as shown in All specimens’ peak stress and confining pressure values were normalized to obtain the variation relationship between the confining pressure value and the peak stress shown in Firstly, the specimen’s lateral deformation was restricted by the constraining impact of the confining pressure value, leading to an increase in the axial load capacity and a rise in peak stress. Increasing the value of the confining pressure resulted in a sharp increase in the deformation capacity of the concrete. The part beyond the material’s own deformation was compensated by the development of cracks. The fine cracks inside the specimen steadily expanded. Coral aggregate has a certain brittleness, so the higher the load that the specimen is subjected to when it is under hydrostatic pressure, the easier it is for the specimen to produce microcracks that affect the peak stress before the effective loading. Large confining pressure values and axial pressures can easily lead to brittle fracture or crushing of coral aggregates, resulting in a slower growth rate of peak stress.According to the test data, we normalized the peak stress of each group of specimens to combine with the confining pressure value for dimensionless analysis and fit to obtain the formula for calculating the peak stress of polypropylene fiber all-coral seawater concrete under different confining pressure values:0σ denotes the peak stress of the specimen under a uniaxial compression state; vσ denotes the peak stress of each group of specimens under different circumferential pressures; wσ denotes each group corresponding to the confining pressure value.V = 3 kg·m−3 and lowest for fiber content V = 2 kg·m−3 at a low confining pressure value. With the increase in the confining pressure value, the peak stress of the specimens with V = 1 kg·m−3 fiber addition was higher than that of other ratios, and the effect of different fiber doping was gradually reduced.V = 2 kg·m−3. This shows that the different dosing of polypropylene fiber affects the peak stress. However, when the confining pressure value increased, the crack-arresting effect of polypropylene fiber was continuously weakened because the crack-arresting effect of the confining pressure value was more effective than that of polypropylene fiber. The fracture-stopping effect of the circumferential pressure value was more effective than that of polypropylene fiber, and the fracture-stopping effect of polypropylene fiber was weakened continuously as the circumferential pressure value increased. Polypropylene fibers were influenced by the combined positive effect of bridging and crack resistance and the negative effect of fiber agglomeration. To ensure the enhancement of the deformation performance of polypropylene fibers on all-coral seawater concrete to produce higher peak stresses at different values of circumferential pressure, it is recommended that the fiber dosing be equal to V = 3 kg·m−3.The normalized peak stresses of all-coral seawater concrete with different fiber admixtures are given in wσ = 18 MPa, the peak strain of the specimen was 9.2 times that of the case without the constraint of the confining pressure value. On the one hand, the increase in peak strain was due to the confinement of the confining pressure value, which increased the elastic range of the specimen. The surface of coral aggregate is rough, and the specific surface area of porous structure is large. This made the cement matrix have a firm grip on the aggregate, and the bonding interface was strengthened significantly. On the other hand, the increased confining pressure value limited the development of microcracks to vertical penetration cracks. The plastic deformation of the specimens at peak strain also increased gradually due to the extrusion flow of cement mortar and the generation of fine cracks. The plastic deformation capacity of the polypropylene fiber all-coral seawater concrete increased substantially, which led to a significant increase in the peak strain of the specimens.According to the experimental data, the formula for the peak strain of polypropylene fiber all-coral seawater concrete under different confining pressure values was fitted:0ε is the peak strain in the uniaxial compression state of the specimen.wσ ≤ 12 MPa, some specimens will be affected by local early damage to the weak zone when the oblique main crack mostly causes deformation of the specimen. In addition, the remaining portion of the specimen was less deformed, resulting in most of the polypropylene fibers bridging and the crack resistance not being fully developed. Therefore, the fiber content increased at this time, and the peak strain of the specimen grew more slowly. When 12 MPa ≤ wσ ≤ 18 MPa, the peak strain of the specimen increased significantly with the increase in the confining pressure value. Lateral restraint increased the friction between the complete coral aggregate and the cement matrix so that the deformation capacity of the specimen was further increased. Since the prominent cracks of the specimen gradually disappeared and the fine cracks increased, more polypropylene fibers inside the specimen were involved in crack-arresting so that the peak strain of the specimen increased.The trend of peak strain for each group of specimens with different polypropylene fiber content is given in V = 2 kg·m−3, at which time the peak strain increased by about 18% overall.wσ ≤ 6 MPa. Next, the confining pressure value increased, and the rate of increase in elastic modulus gradually decreased because the confining pressure value constrained the lateral deformation of the specimen, resulting in an increasing elastic modulus of the specimen. However, as the confining pressure value increased, the internal voids of the concrete were continuously compressed at higher stress levels, resulting in a decrease in the rate of increase in the elastic modulus.According to the experimental data, the formula for calculating the elastic modulus of polypropylene fiber all-coral seawater concrete under different confining pressure values was fitted:E0 is the elastic modulus of the specimen under uniaxial compression state.V = 3 kg·m−3 compared to other reinforced specimens.V = 3 kg·m−3 was the largest—14.9% higher than that with fiber content V = 1 kg·m−3. The average modulus of elasticity at fiber doping V = 2 kg·m−3 was 9% lower than that at V = 1 kg·m−3. With the addition of fibers, the elastic modulus was generally maintained at about 7 GPa after the peritectic pressure reached 18 MPa, an increase of 27% compared to the uniaxially compressed case. Its elastic modulus was higher than the concrete specimens without fiber admixture.As shown in cμ is used to express the ductility size of all-coral concrete, which is calculated as follows:In order to study the degree of influence of confining pressure value and fiber addition on the ductility performance of all-coral seawater concrete, the ductility coefficient uε denotes the strain corresponding to the end of damage or loading of the specimen; yε denotes the yield strain.wσ = 6 MPa compared to when wσ = 0 MPa. When wσ ≥ 6 MPa, the ductility coefficient started to decrease gradually but overall was still substantially higher than the uniaxial compression. The constraint effect of the confining pressure value improved the bearing capacity and deformation capacity of the specimen and increased the elastic interval of the specimen. The ductility coefficient measured at this stage was more accurate, and the faster growth of the ductility coefficient at this time indicates that the restraining effect of the confining pressure value can effectively improve the ductility of the all-coral concrete. When wσ ≥ 12 MPa, the deformation capacity of the specimen was further improved, and its stress–strain curve gradually leveled off after reaching the peak. The ductility coefficient shows a decreasing trend when the confining pressure value continues to increase, and the ductility coefficient stabilizes at about 1.45 when the confining pressure value is higher.A schematic diagram of the yield strength of the specimen using the isoenergetic method is shown in vε/0.7vε. Therefore, the effect of its modification on the ductility coefficient of polypropylene-fiber-reinforced all-coral concrete after the confining pressure value reaches 12 MPa remains to be further investigated. In addition, the overall ductility coefficient of the specimens tended to decrease first and then increase with the increase in fiber content. From the overall analysis, the ductility improvement was the least for fiber admixture V = 2 kg·m−3, and the ductility of all-coral concrete specimens with fiber admixture V = 3 kg·m−3 was better.All specimens showed residual strengths that were more than 85% of the peak stress after loading, indicating that they are not damaged. Due to a rise in confining pressure value, the peak strain progressively approached the strain after the loading cycle, resulting in the computed ductility coefficient values’ convergence at Q) when the specimen is damaged (the stress of the specimen is reduced to 85% of the peak stress). The actual energy consumption of the specimen is calculated using the following equation listed in The triaxial compression process of polypropylene-fiber-reinforced all-coral seawater concrete was accompanied by energy dissipation. The dissipated energy increased to a certain extent when the specimen released energy by generating and developing cracks in the form of thermal energy. In order to analyze the relationship between the actual energy consumption and the confining pressure and the amount of fiber, and to avoid the influence of the loading time on the accuracy of the energy consumption of the specimen, the integral area of the whole stress–strain curve is not used as the actual energy dissipation of the specimen. As shown in uε denotes the longitudinal strain of the specimen when the bearing capacity is reduced to 0.85 times the peak stress, σ denotes the stress at each moment during the loading of the specimen, and ε denotes the strain of the specimen.wσ and the actual energy consumption Q is obtained by fitting:The function between the confining pressure value Q0 denotes the actual energy consumption of the specimen in uniaxial compression.wσ = 18 MPa, the energy consumption coefficient reached the maximum, which is about 39 times higher than that in the uniaxial compression state. The principal ways of consuming energy are the deformation of concrete components and the development of internal cracks. Thus, the specimen’s energy consumption increased mainly due to strength enhancement and the development of cracks. On one hand, the growth of energy consumption after mixing polypropylene fibers into the fiber skeleton restrained the lateral deformation of concrete, leading to an increase in the energy consumed by concrete due to elastic and plastic deformation. On the other hand, the fibers consumed energy in stretching and pulling to limit the development of cracks within the concrete.D is introduced to describe the degree of damage during the loading of the specimen, which is obtained according to the strain equivalence assumption [In order to describe the damage development process of polypropylene fiber all-coral aggregate seawater concrete specimens during loading, the damage development of the specimen was quantitatively analyzed. According to the continuum damage mechanics theory, the damage variable sumption .(7)D=1−σ, σ* are the effective stresses in the n-direction before and after the damage, respectively; E0 is the elastic modulus in the non-damaged state (taken as the secant modulus at the point where the stress in the rising section of the curve increases to 40% of the peak stress); E* is the effective secant modulus after damage (taken as the secant modulus at each point on the stress–strain curve).wσ = 0 MPa. Before ε < 6 × 10−3, the axial load was small, the specimen was in the elastic stage with almost no damage, and the D value tended to zero. After ε > 6 × 10−3, the specimens showed initial damage, the damage coefficient increased linearly, and the damage occurred very rapidly. Once the load reached the peak stress, the cracks developed rapidly into vertical through-cracks. The axial bearing capacity of the specimen decreased rapidly, and damage occurred suddenly when the damage factor was close to 0.8. According to the analysis of wσ ≤ 6 MPa, with the increase in the confining pressure value, the strain of the specimen was more significant when the initial damage occurred, and the growth rate of the damage coefficient was obviously slowed down. This indicates that the presence of the constrained pressure value delayed the appearance of specimen damage. In addition, it delayed the appearance of specimen damage and effectively slowed down the development of specimen damage. When the confining pressure value was 6 MPa ≤ wσ ≤ 12 MPa, the specimen was already pressurized before the effective loading. This is because the target confining pressure value has a considerable significance value. This can cause some damage to the specimen before the effective loading. Comparing the curves in wσ ≤ 18 MPa, the growth of the damage coefficient gradually tended to level off with the increasing strain.As shown in The restraining effect of the confining pressure value effectively reduced the degree of damage to the specimen, slowed down the development process of damage to the specimen, and prevented the generation and development of cracks; even when the coral aggregate inside the specimen was brittle or crushed, evident damage phenomena did not occur within the specimen. Comparing (1)wσ ≥ 18 MPa, the crack pattern changed to transverse shear damage, the main crack of the specimen disappeared, and the residual deformation increased.From the observation of the damaged specimens, the amount of polypropylene fiber addition and the confining pressure value have a significant influence on the mechanical strength of the specimens. The polypropylene fiber effectively reduced the crack width of the specimen and ensured the relative integrity of the specimen after damage. The crack pattern changed from vertical splitting damage to oblique splitting damage, and the width of the main crack decreased as the confining pressure value increased. The confining pressure value increased, and the crack pattern transformed into diagonal shear failure. When (2)Confining pressure value improves the plastic deformation capacity of polypropylene fiber all-coral seawater concrete, reduces the risk of local concrete instability, prevents vertical penetration cracks, increases axial bearing capacity, and increases peak stress, peak strain, and elastic modulus. When the confining pressure reached 18 MPa, the peak value of the curve disappeared completely. The post-peak curve rose slowly, and the peak stress of the sample was 4.66 times that of uniaxial compression.(3)The microstructure of polypropylene fiber was observed by scanning electron microscope. It was found that the surface of polypropylene fiber was smooth, long, and thin. Coral aggregate has a large apparent density and internal friction angle, which is helpful in improving the interfacial adhesion between aggregate and hardened mortar. The strength of concrete has been improved to a certain extent. Fiber is like microreinforcement, and its random and uniform three-dimensional spatial distribution can prevent the aggregate from sinking in the concrete. The fiber may bridge fractures and enhance the interface transition zone’s stability. It partially compensates for concrete imperfections and regulates the plastic shrinkage of concrete, effectively preventing the initiation and propagation of microcracks in fresh concrete.(4)wσ = 6 MPa, the ductility coefficient of all-coral seawater concrete increases by 133% compared with that of wσ = 0 MPa; when wσ ≥ 6 MPa, the ductility coefficient begins to decrease gradually, but the overall is still substantially higher than the uniaxial compression. The ductility increase is the smallest when the fiber content V = 2 kg·m−3.When (5)wσ ≤ 6 MPa, and with the increase in fiber addition, the actual energy consumption shows a trend of first increasing and then decreasing, and with the further increase in the confining pressure value, the actual energy consumption tends to be stable. When wσ = 18 MPa, the energy consumption coefficient reaches the maximum, about 39 times higher than that in the uniaxial compression state.The actual energy consumption increases and then levels off as the confining pressure value increases. When 0 MPa ≤ (6)wσ ≤ 18 MPa, the strain of fiber-doped concrete when the initial damage occurs is almost twice the initial damage strain of fiberless concrete.In general, the specimen’s damage coefficient curve becomes more oblong when the confining pressure value is raised. The later the initial damage appears, the slower the damage development process and the lower the damage degree. When 12 MPa ≤