Cichla spp.) originates from the Neotropical environments of Brazil and Venezuela but, through trade and smuggling for aquarium keeping, sport fishing and aquaculture, it is now an emerging concern. Yet, less is known for Cichla spp. distribution and its ability to invade new environments. Aimed to communicate on Cichla spp. ecology, biology and introduction schemes from Scopus, Web of Science, Google Scholar and also National Centre for Biotechnology Information, this review also contains management strategies for invading fish species. While Cichla spp. can displace native fish populations, this concern is explained using ecological functions, physiological demands, direct and secondary invasion, disease tolerance and parasite spillover. Briefly, Cichla spp. has rapid embryogenesis (72 h) and matures in short periods (11–12 months), giving it an advantage to colonize new environments. With a large appetite, this true piscivore gains territorial control over water bodies by making it their feeding and nursery grounds. Perceived as an emerging concern after becoming introduced, seal-off or sport fishing were used to manage Cichla spp. but, this practice is not sustainable for the entire ecosystem. Hence, we recommend bottom-up management that involves community participation because they interact with the fish and have knowledge about their environment.Peacock bass ( Cichlid; Peacock bass; Fisheries; Management; Ecology; Invasive; Animal physiology; Biodiversity; Ecosystem services; Environmental risk assessment; Nature conservation. These fish were involved in pet trade, game fishing and aquaculture and therefore, have become emerging concerns in areas they were introduced , has distinct body markings and is endemic to Brazil and Venezuela. Researchers around the world consider Cichla spp. as a voracious predator that hunts and swallows their prey entirely  were having bands and blotches of C. kelberi, coloration of C. temensis . At present, the argument is less conclusive because of sample size. Therefore, with an aim that focuses on history, biology and ecology , introduced Cichla spp. is communicated as an emerging concern. This review also contains sustainable measures for  invading fish species. Overall, exploring the social ethology and behaviour change of introduced fish allows researchers to predict the possibility of emerging concerns and plan for timely interventions.Identification for  English . Howevertemensis  and pose2The inclusion and exclusion procedure followed protocols of 33.1Cichla spp. were identified having a bass-like shape and colourful body patterns (C. pleiozona - four and C. piquiti - five) and black-encircled gold annulus are general morphology markers for Cichla spp. aside from the red colour at centre of the caudal keel that appears distinct to certain species , brown-green , C. mirianae), light grey (C. temensis (P), C. piquiti) and blue-green (C. melaniae) variations.A total of 15 patterns . Three v species . With foCichla spp. has a size range of 30–60 cm, weighs 3–6 kg when matured and can survive up to 69 years  which also includes the appearance of a nuchal hump (fatty tissue deposit) on the forehead of male Cichla spp.  in Lake Keneret (Israel) over the course of 22 years because it is deep, has oxygenic waters and contains sufficient food sources , lukanani (Hawaii), and pavón (Spanish speaking countries), while butterfly peacock, eyespot cichlid and peacock bass are general English references for hla spp. . Most Ciped bars . Aside fmunities . In factsh trade . Hobbyisividuals . It only sources .Figure 33.2.2Cichla spp.  whereas only C. ocellaris into Lake Gatun (Panama) after the 1967 damming projects, this action was convincing to be able to attract anglers, improve wild stock diversity and increase the inland capture fisheries earnings  are reasons for its translocation world wide  to catch-and-release fishing  were introduced into Asia and Floriano (Brazil) for food security  and water temperatures (26–29.2 °C) of tropical environments while also experiencing 77 % rapidness for their growth rates and are able to produce offspring that are tolerant to similar conditions   after they escaped from aquaculture pens (While aforementioned studies show that brief durations (1–3 years) are sufficient for ter body . Yet, on America . Since t(Panama)  and Laje(Panama) . Even thure pens .3.4Cichla spp. is an emerging concern for its predatory behaviour. Unaware to many, this cichlid may also introduce disease causing microbes and parasites into new environments. While transitional weather influences fisheries distribution in river systems (Dactylogyrus sp. (monogenea or gill fluke) completes its life cycle in mouth- and substrate brooding cichlids and this makes Cichla spp. vulnerable to parasitism , the spillback of Tilapia Lake Virus onto C. monoculus occurs after its interaction with Oreochromis sp.  in Timah Tasoh, Malaysia  of International Union for Conservation of Nature (IUCN) and therefore, the Agenda 2030 is becoming challenging to achieve . In addi habitat . Rapid a habitat .Cichla spp. were developing taskforce to control its widespread in affected water bodies but, their actions were delivered to the entire area rather than isolating the target from the non-target species  before its movement within zones that are free from this species. By far, successful management can only be accomplished by collaboration  where decision-makers and communities work together to form an understanding. The breach of this understanding has a scale of (legislation) that also require compensations (fines and punishments)  of assessments (and review of action plan) so that early signs of local invasion is revealed  is able to scale every decision with a rate so that authorities can choose the most effective approach . For insshments) . This shshments) . For insrevealed . Overallrevealed  is alrea4Cichla spp. as a non-native species with potential to become an emerging concern in North America, Africa and Asia. We learnt that 15 species of Cichla exists and they are distinguished by 3–5 horizontal band marks along with gold outline black anulus where only C. kelberi, C. monoculus, C. ocellaris and C. temensis were sought for sport fishing, aquarium keeping and aquaculture. Also, Cichla spp. requires 11–12 months to mature in which the larvae and juvenile adopt mixtroph diets whereas the sub- and mature-adults are true piscivore. The ability of Cichla spp. to cause active (predation) and passive (parasite and disease spillover) invasion is limited to environment settings and underlying threats. Implementations such as poison bait, electric fishing and intensive angling have been used over the years to suppress Cichla spp. overpopulation. However, these implentations were unreliable because decision are made by authorities that do not understand the biology of Cichla spp. after becoming introduced into tropical and sub-tropical regions. Therefore, we utilize secondary data to map Cichla spp. availability outside their native geographies while highlighting weaknesses such as top-down, short-term, conflicting interest and poor decision making as management failures. We recommend an updated management strategy that uses measures to detect, acquire, execute and track resources after taking into consideration ‘crowd wisdom’, horizontal screening and machine learning for short- and long-term strategies which need to be reviewed in a sequence of 2, 5 and 10 years. Additional suggestions include:I.Cichla. Defected Cichla spp.  are either, intolerant to the environment or sterile.Develop knowledge on genetic or protein manipulation that produces defected II.Cichla spp. must be regulated by a local legislation where aquarium dumping or active release of this fish into the wild is regarded an offence and punishable by law.Introduction schemes for III.Future studies should be aligned with the SDGs (Agenda 2030) and membered by experts from various fields, education, and occupation.IV.Current local, regional, and international databases on successful eradication or otherwise should be developed and disseminated among the researchers, authorities and policymakers.V.The annual monitoring of an introduced species is an effective way of early invader detection. Zoning must be implemented to control their movement.VI.Engaging the public with invasive species management gathers opinions from crowds whereby this form of transparency convinces the public that actions are measurable and have an outcome.VII.Conservation and economic gains should be themed with sustainability so that resource governance contains compensation schemes for communities whose livelihood becomes vulnerable after such impacts.This article communicates on All authors listed have significantly contributed to the development and the writing of this article.This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.The authors declare no conflict of interest.No additional information is available for this paper.


Staphylococcus aureus is a highly successful Gram-positive pathogen capable of causing both superficial and invasive, life-threatening diseases. Of the invasive disease manifestations, osteomyelitis or infection of bone, is one of the most prevalent, with S. aureus serving as the most common etiologic agent. Treatment of osteomyelitis is arduous, and is made more difficult by the widespread emergence of antimicrobial resistant strains, the capacity of staphylococci to exhibit tolerance to antibiotics despite originating from a genetically susceptible background, and the significant bone remodeling and destruction that accompanies infection. As a result, there is a need for a better understanding of the factors that lead to antibiotic failure in invasive staphylococcal infections such as osteomyelitis. In this review article, we discuss the different non-resistance mechanisms of antibiotic failure in S. aureus. We focus on how bacterial niche and destructive tissue remodeling impact antibiotic efficacy, the significance of biofilm formation in promoting antibiotic tolerance and persister cell formation, metabolically quiescent small colony variants (SCVs), and potential antibiotic-protected reservoirs within the substructure of bone. Staphylococcus aureus is the leading cause of osteomyelitis, which is defined as inflammation of bone but is most commonly encountered in the setting of bacterial infection. Osteomyelitis can result in significant morbidity such as progressive bone damage, pathologic fractures, and septicemia  and the major histocompatibility complex (MHC) class II analog protein (Map)  , 12. Mapin (Map) .S. aureus immunoevasive factors also contribute to the formation of abscesses, which are the characteristic tissue lesions of invasive staphylococcal infection and consist of a three-dimensional community of bacteria surrounded by immune cells. This physical segregation of bacterial cells from the surrounding host tissue is predicted to protect pathogens from both the host response and antibiotic treatment   and persisters are two phenomena reflective of the altered metabolic activity of bacteria within biofilms . PersistB (sigB) –42. A vaB (sigB) , 44. SpeB (sigB) –50. In tB (sigB) , 52.The increased antibiotic tolerance observed with persisters and SCVs is suggested to be a result of their altered metabolic activity , 53, 54.S. aureus remained relatively unclear until recently. In Escherichia coli, persister formation is linked to toxin-antitoxin modules; however, when this was investigated in S. aureus it was found that the deletion of these modules did not influence the levels of persisters  developed to model S. aureus invasion of the OLCN, Masters et al. screened select transposon mutants and were able to identify penicillin binding protein 4 (PBP4) as critical to OLCN invasion (Lastly, efforts are now being focused on identifying novel drug targets that are critical for invasion . In a muStaphylococcus aureus osteomyelitis remains a serious health threat given the significant morbidity and treatment recalcitrance of these infections. S. aureus not only is able to adapt to changing host environments and evade the host immune response, but it also has multiple mechanisms to promote tolerance to antibiotic treatment. As a result, treatment of osteomyelitis requires long term antibiotic therapy, often in combination with surgical debridement which can further increase osteomyelitis morbidity. In order to improve the outcome of osteomyelitis treatment and reduce the risk of relapse, a greater understanding of the tolerance mechanisms used by S. aureus to survive antibiotic treatment is essential. Furthermore, when developing novel treatment strategies, it should be considered that the effectiveness of treatments in vitro in a clinical microbiology setting may not be an appropriate representation of effectiveness in vivo.JC: conceptualization, writing—reviewing and editing, supervision, and funding acquisition. BG: writing—original draft preparation and visualization. Both authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Background: In order to tackle the public health threat of antimicrobial resistance, improvement in antibiotic prescribing in primary care was included as one of the priorities of the Quality Premium (QP) financial incentive scheme for Clinical Commissioning Groups (CCGs) in England. This paper briefly reports the outcome of a workshop exploring the experiences of antimicrobial stewardship (AMS) leads within CCGs in selecting and adopting strategies to help achieve the QP antibiotic targets. Methods: We conducted a thematic analysis of the notes on discussions and observations from the workshop to identify key themes. Results: Practice visits, needs assessment, peer feedback and audits were identified as strategies integrated in increasing engagement with practices towards the QP antibiotic targets. The conceptual model developed by AMS leads demonstrated possible pathways for the impact of the QP on antibiotic prescribing. Participants raised a concern that the constant targeting of high prescribing practices for AMS interventions might lead to disengagement by these practices. Most of the participants suggested that the effect of the QP might be less about the financial incentive and more about having national targets and guidelines that promote antibiotic prudency. Conclusions: Our results suggest that national targets, rather than financial incentives are key for engaging stakeholders in quality improvement in antibiotic prescribing. Clinical Commissioning Groups (CCGs) were established in the English National Health Service (NHS) in April 2013 as the statutory bodies responsible for the planning and commissioning of health care services for their local area ,5,6,7, tThis paper briefly reports the key findings from a workshop with antimicrobial stewardship (AMS) leads, which aimed to explore the experiences of selecting and adopting strategies within CCGs to help achieve the QP targets on improving antibiotic prescribing. We have also reported a concept mapping activity by the CCGs to develop a conceptual framework for modelling the mechanism of QP effect on antibiotic prescribing.Participants were sent an invitation letter via email with details of the study. We invited 80% of the AMS leads for the 191 CCGs in England (as of May 2019) [Participants were assigned to one of three small groups, and each group had a researcher to observe and record discussions. In assigning participants to small working groups, we aimed to have diverse perspectives and experiences in each group in relation to regions and prescribing behaviour of the CCGs represented by the participants. This was important to facilitate comparison of experiences and drive creativity and inclusiveness in the development of the conceptual framework. Discussions within each small group started with participants identifying and summarising the interventions and strategies adopted in their CCGs towards achieving the QP antibiotic prescribing targets. The second part of the workshop was an interactive activity to build a conceptual model to demonstrate the pathways from the QP to antibiotic prescribing through the identified AMS interventions/strategies , and associations between the identified potential mediators, if any.The modelling activity was followed by a whole-group discussion on key observations about how the QP had been implemented, building on earlier contributions by the participants in the three small groups. This discussion was useful for comparing and summarising the models, looking at triangulation of the data and exploring how the discussed experiences compared between groups and individuals .Detailed notes on discussions and observations within the small and whole groups were taken by PA, AB, CC and other researchers involved in the workshop. The notes were combined and analysed by PA and CC. We conducted a thematic analysis to identify themes across the dataset. The notes were descriptively coded to summarise the key concepts of statements and observations from the group discussions. We reviewed the codes for patterns. Codes that relate to specific fundamental concepts on the experiences of the participants were linked to form themes ,12. To iWe recruited 10 AMS leads, three GPs, and one Nurse Prescriber from a diverse range of CCGs and practices in relation to antibiotic prescribing rates and geographical location. Four of the participants who expressed interest did not attend the workshop.The findings were organised into three main themes, which constituted constructs linking the various aspects of participants’ experiences (discussed below). Increased CCG engagement with practices on prudent antibiotic prescribing: Practice visits, needs assessments, peer feedback and audits were identified as a set of strategies integrated towards increasing the level of engagement between CCGs and practices, and within practices. Some CCGs used practice visits as an avenue to assess what prescribers need to help them reduce their antibiotic prescribing. Audits to assess antibiotic prescribing in practices against national guidelines were commonly adopted by CCGs alongside feedback to practices to motivate change in prescribing to help meet the QP antibiotic targets. Heavy workload in CCGs and practices was identified as the main barrier to regular antibiotic audit in practices. Participants also reported benchmarking local prescribing data against the national and regional averages as a social norm strategy.Local financial incentive schemes: The use of other local financial incentives by CCGs to encourage practices to reduce their antibiotic prescribing was widely discussed with most participants recognising the existence of local incentive schemes even before the QP. Some of the local incentives were integrated with the QP targets from 2015.Other strategies: Other strategies described to help with QP antibiotic targets included the use of AMS training resources—in particular those available on the Treat Antibiotics Responsibly, Guidance, Education, Tools (TARGET) toolkit-, and C-reactive Protein point-of-care testing (CRP POCT).The participants stressed that the identified strategies were not adopted in isolation. For instance, some of the participants described the integration of audit, feedback, practice visits, and a CCG-level incentive scheme. A practice visit by CCG AMS leads (or Prescribing Advisors) was recognised as a strategy used to conduct an antibiotic audit and offer feedback to practices. Additionally, local financial incentives were sometimes set up to encourage practices to conduct self-audit.Increased availability of prescribing data for CCGs and practices: Increased surveillance, availability and feedback of prescribing data following the introduction of QP were perceived to be associated with increased engagement with the QP scheme. This was also reported to be related to increased adoption of strategies like antibiotic audit and benchmarking.National guideline on antibiotic prescribing: Participants also reported that having a national guideline helps in developing local strategies towards the QP antibiotic targets by providing a framework to underpin their AMS activities. In discussing the available guidelines on antibiotic prescribing, most of the participants indicated a preference for guidelines that were less frequently updated given the limited time allocated to AMS duties. In addition, most of the participants shared the view that the effect of the QP might be less about the financial incentive and more about having national targets and guidelines that promote antibiotic prudency. Even when their CCGs expected not to receive the QP financial payments , some participants reported that they still worked towards the QP antibiotic targets.One of the challenges to meeting the QP antibiotic targets reported by the participants was balancing the goal of AMS whilst ensuring access to antibiotics for those patients who needed them .Another reported challenge was engaging high antibiotic prescribers. AMS interventions such as practice visits, audits and feedback were often targeted by the CCGs specifically to high prescribing practices. Participants raised a concern about the possibility of disengagement by high prescribers due to continuously labelling and targeting them for most AMS interventions.Our paper summarises the strategies and activities reported by a selection of CCGs in England to facilitate antibiotic stewardship in primary care practices towards achieving the QP antibiotic targets. Evidence on the mechanism of impact of financial incentive schemes to improve the quality of care in primary care is insufficient given the limited number of rigorous studies on this . We demoOur findings are important to healthcare policymakers and quality improvement agencies in the planning and systemised implementation of programs towards antimicrobial stewardship. The participants reported some of the ways in which AMS strategies such as national guidelines, audits and feedbacks can be integrated to optimise their individual effects. The co-developed conceptual framework can inform a user-led investigation of the mechanism of the impact of financial incentive schemes on antibiotic prescribing in primary care practices. Given that the Quality Premium is one of the first national financial incentive schemes towards improvement in antibiotic prescribing in England, the developed framework depicting pathways for maximising the potentials of such a scheme can be useful in the development of future AMS financial incentive interventions.The adoption of some of the AMS strategies identified in our workshop was also reported by a survey of CCGs in England . PreviouWe recognise the limitation posed by the small sample size with regards to the representativeness of our findings. However, the diversity of the workshop participants  was important in capturing different perspectives and experiences, contributing to the credibility of our findings.


From the perspective of food categories, fresh produce are the leading sources of food loss and waste globally. Their highly perishable nature shortens their shelf-lives leading to high postharvest losses if not properly handled. Currently, these losses are estimated at sixty-six percent based on total weight. Reduction of these losses will ensure constant supply of food along the supply chain as well as economic empowerment of the rural poor. Hexanal which is a naturally occurring compound has been developed as an intervention to prolong shelf-life of delicate tropical fruits such as bananas while also maintaining their quality. However, empirical evidence is still required on the usefulness of hexanal to farmers. It is envisaged that such evidence would inform scaling up of the technology in Kenya. This study assessed willingness to pay for hexanal and the factors influencing WTP amounts among banana farmers in Meru County, Kenya. Primary data was collected from 130 respondents who were grouped into aware and not aware of Hexanal. Results indicate that farmers who are aware of hexanal had a higher mean WTP Ksh 466.47 (US $4.66) compared to those not aware Ksh 331.86 (US $3.32). Factors such as age and income influenced the WTP amounts between subsamples. The major key policy implication of the study is the importance of stakeholders investing in the dissemination of information on hexanal among farmers to enhance uptake. Across the food categories, fruits and vegetables are the major causes of food loss and waste globally. According to literature, these losses are estimated at 66% based on total weight , 2. FresThese losses are higher in developing countries compared to the developed countries . This isMusa spp.) were ranked first in terms of production with 1.24 million tons being produced under 63074 Ha of land which was an increase from the 60743 Ha in 2015. The production was reported to be worth KSh 18.1 billion (US $ 180 million) accounting for 31.6% of the total fruits' production in the country ). th respondent on the list which resulted in a representative sample of 180 households. Systematic random sampling eliminates bias by guaranteeing that each household has an equal opportunity of being selected [From the formula, the ideal sample size for this study was 317 respondents. However, due to constraints in time and resources, systematic random sampling was used in the third stage to select every 10selected . The curInterviews were only conducted with the household head, spouse, or both. Absence of either the head or spouse in a household resulted in termination of the interview, and the household was systematically substituted. Since the households were specifically selected from banana production groups, replacement was only from a specific household list which greatly reduced the sample size. The main challenges encountered during data collection was absence of respondents, a tough terrain, and bad weather which made it difficult in accessing some households as well as increasing costs.n = 52) attended a dissemination workshop where they were trained on the use and benefits of hexanal in February 2018. On the other hand, the control group (not aware) (n = 78) comprised of farmers that did not attend the dissemination workshop and were not aware of the existence of hexanal. Enumerators familiar with the local dialect collected data on sociodemographics of the respondents, farm characteristics, infrastructure, external support services, and WTP values.In the current study, the respondents were categorized into two groups comprising of the treatment and control groups. The treatment group (aware)  approach used to elicit the maximum amounts farmers were willing to pay for hexanal technology. According to , CVM is The choice of elicitation technique to use depends on the nature of good to be valued as well as the resources available for survey. In the case of this study, bidding game technique was used where the respondents were assigned a specific initial bid and were required to answer with a ‘yes' or ‘no' The difference between the dichotomous choice and the bidding game is that in the latter, the process is continuous whereby the interviewer increases the bid amount if the previous response was ‘yes' until they obtain a negative response and reduces the initial bid amount if the previous response was ‘no' up to a point a positive response is obtained and the highest amount the respondent is WTP is recorded .“banana production supports many farmers economically in Kenya. However, lack of access to proper post-harvest handling techniques contributes to great losses of up to 40% each year. There is an organic pre-harvest dip and spray known as Hexanal technology {which is an Enhanced Freshness Formulation (EFF)} that is capable of prolonging fruit shelf life by 21days on the trees and 17 days in storage (at room temperature) to 26 days in cold storage. Field trials carried out in Kenya show it is very effective in prolonging shelf life in mangoes and bananas while causing no harmful effects on humans. The product is currently not available in the market but considering the costs of importation it would cost Ksh.400 (US $4) per 0.25Litres. If the product was introduced in the market and you were required to pay for it, would you be willing to pay for it? Would you be willing to pay Ksh400 per 0.25L?”Data was obtained on the WTP amounts for both groups of farmers who are aware as well as those not aware of the hexanal technology. Farmers who were already aware of the technology were given a brief reminder of the attributes of the technology, how to use the technology, and its' benefits as they had already attended a dissemination workshop on the same. As for the case of farmers not aware of the technology, a hypothetical scenario was provided in order enable the elicitation of the maximum WTP amount from the farmers. Information on mix ratios of Hexanal was explained of diluting 0.25 liters of hexanal with 12.5 liters of water. It was explained to them that the solution would be enough to spray 125 bunches of bananas or dip as many fruits till the solution is completely used. The hypothetical scenario was designed as follows: Iterative bidding was then used to elicit the maximum WTP. First, the enumerator explained to the respondent that they would have to pay cash for the product or purchase it through credit from an agro-dealer and repay later after harvesting. A bid of ±Ksh 50 (US $0.5) was used whereby if the answer was “yes” to the initial amount of Ksh 400 an increment of the bid amount was added until the respondent said “no.” In case the respondent responded “no” to the first amount an equal decrement of the bid used until the respondent revealed the amount they are willing to pay by answering with a “yes.” The revealed amount was recorded as the maximum amount farmers are WTP. The base price of Ksh 400 of the hexanal technology was obtained from the aggregation of the components' current market value/prices used to formulate hexanal.The mean WTP amounts and the factors likely to influence farmers' WTP were all analysed using econometric software Statistical Package for Social Scientists (SPSS) version 20, and STATA version 14. SPSS was used for data entry and cleaning while STATA was used to estimate the mean amounts farmers are willing to pay for the hexanal technology as well as their determinants. Data was analysed separately for the two groups of farmers to obtain differences in WTP amounts and their determinants between the treatment farmers and control farmers.q which is the novel product to be valued; p, prices of market goods; z which is the farmer's characteristics; y representing the farmer's income, and ε representing some stochastic components of preferences of the farmer which are unobservable to the researcher and hence treated as random [V . With introduction of hexanal technology, a farmer is confronted with the opportunity of prolonging freshness of his/her fruits which will require a change from using product q° which is the traditional postharvest handling techniques to q1, which is the hexanal technology that has proved to be effective in prolonging the shelf-life of mangoes, bananas, and pawpaw in Kenya. Hexanal technology is more effective and has greater benefits to the farmer than traditional techniques hence q1 > q°. It is assumed the farmer perceives the change as an improvement in terms of incomes from the reduced losses and hence his/her indirect utility is as follows;In the case of choice discrete response format as is the case in this study, it is assumed a farmer is interested in reducing postharvest losses of his fruits. Therefore, his/her corresponding indirect utility function would depend on s random . TherefoA the farmer would only be willing to pay (by replying “yes”) to the amount only ifHowever, when the farmer is informed that the change would cost Ksh q° to q1 can be expressed using the compensating variation measure whereby C satisfiesThe maximum amount a farmer is willing to pay for a change from C = C  is a farmer's maximum WTP for the change. If the stated price in the bid question is lower than the above WTP, a farmer will answer “yes” and “no” otherwise and henceThus, q° to q1. Alternatively, the WTP for the change in this case is expressed asw is the vector of input prices and p is the vector of output prices, which yields the following indirect restricted profit function π . In reference to equation  variable that is unobservable, β is the vector for some unknown coefficients, and X is the vector for independent variables while ε is the error term which is assumed to be independently distributed with a mean of zero and a variance of σ2.Theoretically, the model is presented as follows :(8)Y∗=XTwo similar regressions for both the treatment and control groups were run using identical sets of independent variables. The estimating equations are as follows:The results show that both groups of farmers in Meru County are willing to pay positive amounts for the hexanal technology . The mint-test testing the hypothesis of equal WTP amounts was rejected at 1% level of significance (p < 0.01). The mean WTP amount for farmers who attended the dissemination workshop is statistically higher than for those who never attended. Specifically, farmers aware of hexanal are willing to pay Ksh 134.61 (US $1.34) more than those ones not aware of the technology. Therefore, the results are an indication that access to information on existence of a new technology increases the acceptance and WTP amounts for the technology. These results are consistent with [It was hypothesized that there would be no difference in the mean amounts farmers are willing to pay between the farmers aware and those not aware of the technology. However, results from ent with  who founent with . For botent with  used the2 statistic for both groups were significant at 1% level of significance (p < 0.01) which is an indication variables included in this regression significantly contribute to the changes in the maximum amount households are willing to pay for hexanal. The pseudo-R2 was 53.15 and 24.25 for the not aware and aware groups, respectively. The values indicate that independent variables included in this model could explain 53.15% and 24.25% variation in the maximum WTP, respectively.Identical sets of independent variables were used in the tobit regression model for both groups of farmers, those aware and those not aware of hexanal. Results on p < 0.01) the maximum WTP for both groups of farmers. This is an indication that increasing the bid amount results in increased mean WTP for hexanal.Among the explanatory variables, the initial bid amount positively influenced  the mean WTP amounts among farmers not aware of the technology. The results are an indication that older farmers not aware of the technology were willing to pay lower amounts for hexanal compared to younger farmers. These findings are consistent with [Age of the respondent negatively influenced . This means the mean WTP amounts were less for male farmers compared to female farmers. According to a study by [Gender of the respondent  was found to negatively influence the mean WTP amounts among households aware of hexanal (study by  on gendep < 0.05) among the farmers who attended the dissemination workshop and are aware of the hexanal. Farmers who practice farming as their main occupation had reduced WTP amounts compared to farmers engaging in other nonfarm activities. This could be explained in that farmers involved in other activities viewed hexanal a solution to save time spent on farm activities and looking for markets, which increased the demand of hexanal among them.The explanatory variable ‘main occupation of the respondent' negatively influenced WTP amount (p < 0.05) WTP amounts among famers aware of the technology. Married farmers were more likely to pay higher amount for hexanal compared to the unmarried if they perceived hexanal capable of increasing their incomes which would enable them take better care of their families.Marital status of the respondent (being married) positively influenced (p < 0.1) among households not aware of the technology. Living far away from market centres reduced a farmer's WTP amount. The disincentive for this group of farmers could be from lack of information on the uses and benefits of hexanal in prolonging the shelf-life of the fruit and therefore causing farmers to incur more transaction costs in search of the information leading to low demand for the technology. This variable had no significant influence on the WTP among farmers aware of hexanal.Distance to the market center negatively influenced the WTP amounts (p < 0.1) the WTP amounts among farmers aware of the technology. Farmers with larger farm sizes were willing to pay higher amounts for hexanal to reduce postharvest losses due to their high production of bananas. A larger land size under banana production meant increased output which required good postharvest handling to avoid losses. This led to the increased demand for the technology among farmers already aware of the benefits of hexanal [Land size which was measured in acres positively influenced  on the WTP amounts among farmers who were aware of hexanal. Households obtaining higher incomes from banana production were willing to pay higher amount for hexanal. Income can be used as a proxy for a household's ability to purchase quality farm inputs. This is consistent with the broad range of literature which shows that households with higher incomes have higher chances of being early adopters of new technologies [The variable income  had a positive influence  among farmers not aware of the technology. Households that perceived hexanal to be a socially acceptable product which they would be able to incorporate it as one of their post-harvest management practices were willing to pay higher amounts for it. The findings concur with [The perception on social acceptance of the technology positively influenced the maximum WTP (cur with  who founThe study is aimed at assessing the WTP amounts for hexanal and the factors influencing them among banana farmers in South Imenti subcounty. Overall, farmers are willing to pay positive amounts for the hexanal technology. This provides sufficient guide on the pricing mechanisms for the technology developers and the extension providers. In addition, farmers who were aware of the technology had higher WTP amounts compared to those not aware of the technology which explains the critical role of information in enhancing the acceptability/adoption of a technology.WTP was influenced by several factors between the two groups. Factors that positively influenced WTP included initial bid amount, marital status, land size, income, and perception on social acceptability of hexanal. On the other hand, age, gender, main occupation, and distance to market center were found to negatively influence WTP amounts. Therefore, product developers should ensure pricing of the technology takes into account the households' sociodemographic characteristics that were found to influence amounts farmers are willing to pay.Therefore, stakeholders should provide sufficient information in order to enhance perception on social acceptability of the technology as it was found to positively influence the WTP. Since distance to market center negatively influenced WTP, extension providers should educate farmers living away from town centers through farmer field days and trainings to increase awareness on hexanal in order to enhance its adoption. Farmer's age negatively influenced WTP among farmers not aware of the technology; hence, there is a need for product developers to conduct more dissemination workshops among younger farmers not aware of the technology in order to demonstrate the effectiveness of the technology.The current study only focused on the WTP amounts and did not consider if hexanal is actually profitable for use by the banana farmers. Assessing the cost-benefit analysis of the technology is therefore a potential area of future research. Output from the cost-benefit analysis could be useful in providing more evidence for increased dissemination and commercialization of the technology as well as aiding farmers in making more informed investment decisions.


Tg) measurements. Thermomechanical and SME properties were characterized using dynamic mechanical analysis. It was found that SMPs containing amine-based POSS show higher Tg, better shape fixity and faster recovery speed, while SMPs containing epoxide-based POSS have higher crosslinking density and show superior thermomechanical properties above Tg. This work demonstrates how the Tg and SME of SMPs can be controlled by the type and amount of POSS in an epoxy-based SMP nanocomposite for future space applications.Thermally activated shape memory polymers (SMPs) can memorize a temporary shape at low temperature and return to their permanent shape at higher temperature. These materials can be used for light and compact space deployment mechanisms. The control of transition temperature and thermomechanical properties of epoxy-based SMPs can be done using functionalized polyhedral oligomeric silsesquioxane (POSS) additives, which are also known to improve the durability to atomic oxygen in the space environment. In this study, the influence of varying amounts of two types of POSS added to epoxy-based SMPs on the shape memory effect (SME) were studied. The first type contained amine groups, whereas the second type contained epoxide groups. The curing conditions were defined using differential scanning calorimetry and glass transition temperature ( The volume and mass budgets of spacecraft are limited. Hence, spacecraft have to be equipped with lightweight, compact, reliable built-in mechanisms for the deployment of antennas, radiators, solar arrays, optical systems, and more. The demand for lighter and smaller deployment systems increased recently due to the growing interest in the so-called “new space” nanosatellites . A classTg [Thermally activated SMPs can memorize a temporary shape at low temperature and return to their permanent shape at higher temperature. The molecular switches are able to reduce their stiffness upon a particular stimulus—in our case, temperature, allowing the polymer to be programmed into its temporary shape and maintain this temporary shape as the SMP is cooled below a certain threshold temperature. The SMP can return to its permanent shape following heating above this threshold temperature. Usually, this threshold temperature is the SMP’s glass transition temperature, Tg . SMPs caTg .SMPs have many benefits for space structures compared to traditional mechanisms, such as lightweight, low cost, high specific modulus, high storage energy ability, and predictable recovery upon exposure to external stimulus ,12. Furt2) or indium tin oxide (ITO). However, such protective layers can be damaged due to hypervelocity debris impact, as well as by ground-based handling [1.5 POSS into SiO2 [Tg and the Young’s modulus of epoxy-based polymers, and it can improve their mechanical, chemical, thermal, and electrical properties [In space, qualified SMPs must withstand the harsh space environment. The space environment is characterized by severe conditions such as hypervelocity micro-meteoroids and space debris impacts, ultrahigh vacuum (UHV), ionizing radiation, ultraviolet (UV) and vacuum UV radiation, electrostatic discharge, extreme thermal cycles, and hyperthermal atomic oxygen (AO). The most destructive elements for organic materials selected for low Earth orbit (LEO) space applications are UV radiation and AO ,22,23. Ahandling . A potenhandling ,27,28,29handling ,31. Depehandling ,33. The operties ,48,49,50Most of the previous studies of epoxy and POSS have used diglycidyl ether of bisphenol A (DGEBA) resin ,48,49,50Tg and excellent shape recovery due to the nature of its permanent chemical crosslinking [In recent years, studies of the influence of POSS on the SMP properties gained attention in the SMP community ,57,58,59slinking .Tg, were characterized using dynamic mechanical analyzer (DMA). DMA also enabled the calculation of the crosslinking densities of different EPOSS compositions. The effect of the POSS type and content on the shape memory properties was studied quantitatively, in terms of shape recovery, fixity, and recovery speed. Finally, the effect of the shape memory effect (SME) cycle on the bending stress was studied.Previous studies concentrated on the effect of addition of a single type of POSS molecule on the shape memory properties of SMPs ,57,58,59In this work, POSS with eight epoxide (EP) functional groups was used to gradually replace an equivalent amount of EPON 826 resin, a rigid aromatic epoxide with two functional groups. Another type of POSS, containing eight secondary amine (AM) functional groups was used to substitute an equivalent amount of Jeffamine D230 crosslinker—a primary aliphatic diamine with four reactive hydrogen atoms. The effect of AM and EP content on the curing and post-curing processes of EPOSS was studied using DSC. The results were used to derive the degree of curing of various compositions.DSC thermograms taken during curing and post curing of the epoxide-based EPOSS and amine-based EPOSS formulations, denoted hereafter as EP–EPOSS and AM–EPOSS, respectively, are shown in As shown in the inset of Tg, as it correlates with the crosslinking density; Tg increases as the crosslinking density increases [According to ncreases .Tg values for 50 AM as a function of post-curing time were measured by both DSC and DMA, as shown in Tg values derived from DSC were lower by about 20 °C in comparison to those deduced from DMA, which is in agreement with previous works [Tg was substantial up to 3 h. Tg increased from 95 to 108 °C according to DMA or from 72 to 85 °C according to DSC. The addition of another hour had no influence on Tg.us works ,51. AccoThe degree of curing was extracted from the DSC thermograms for each EPOSS composition, as shown in The reduction in the degree of curing may be due to steric interferences resulting from the size of the POSS molecules as well as their functionality. Both the AP–POSS and EP–POSS molecules have eight functional groups, while the original epoxy resin and crosslinker monomers have two and four (two primary and two secondary amines) functional groups, respectively. This means that compared to the original monomers, the steric availability of the functional groups attached to the POSS molecules may be reduced . MoreoveTg values obtained using DMA for different EPOSS compositions. In the case of EP–EPOSS, as the EP–POSS content increased, the Tg decreased sharply from 104 °C for pristine epoxy to 50 °C for 73 EP. For the AM–EPOSS, Tg values moderately decreased from 104 to 95 °C as the AM–POSS content increased to 30 wt.%. As the AM–POSS content was further increased from 30 to 50 wt.%, Tg values increased from 95 to 110 °C.Tg decreased. Tg is affected by crosslinking density and chain mobility [Tg indicates that the addition of EP–POSS leads to an increase of the chain mobility. This phenomenon can be explained by the fraction of POSS molecules that are not chemically crosslinked and are present in the matrix as molecular fillers. Thus, the free volume of the matrix increases to a state where the chains are more flexible and mobile; therefore, Tg decreases [According to the degree of curing see , most ofmobility . Therefoecreases .Tg was expected to decrease. However, the measured values are similar to the Tg of pristine epoxy for most compositions, and they are even slightly higher in the case of 50 AM. A possible explanation is that most of the AM–POSS molecules serve as physical crosslinkers, for example through π–π interactions between phenyl groups of the AM–POSS molecules and bisphenol A groups from the epoxy resin [Tg and storage modulus [Tg [In the case of AM–EPOSS, the low degree of curing  indicatexy resin ,66,67,68 modulus . Anotherulus [Tg ,70.Tg results shown in The effect of the POSS type and content on the storage modulus at 30 °C was studied, as shown in Tg, for all studied compositions. The storage modulus increased when the POSS content was increased for both types of POSS, see Tg, the dominant factor that dictated the polymer elasticity was the crosslinking density, which enabled them to store elastic energy.A different phenomenon occurred at 120 °C, i.e., above the −6 mol/cm3 for pristine epoxy to 4.2 × 10−5 mol/cm3 for 73 EP. Despite AM–EPOSS exhibiting a much lower degree of curing than pristine epoxy, the crosslinking density of these samples hardly changed as POSS was added to the system, excluding the 50 AM. The latter presented a slightly higher crosslinking density than pristine epoxy, 7 × 10−6 mol/cm3. This means that for each equivalent of Jeffamine D230 chemical crosslinker replaced with AM–POSS, the same amount of physical crosslinking was formed. In addition, the excess of POSS molecules served as molecular fillers in both types of POSS. The crosslinking density was calculated based on the storage modulus in the rubbery region, combining the effects of the chemical and physical crosslinking density as well as the molecular filler density. These results indicate that above Tg, the chemical crosslinking formed by the EP–POSS was more dominant than the physical crosslinking formed by the AM–POSS, leading to higher crosslinking density and storage modulus values at 120 °C.The difference between the degree of curing and the crosslinking densities arise from the fact that the degree of curing is related solely to heat released during the curing process by chemical reactions, such as polymerization, crosslinking, etc. However, crosslinking density depends not only on chemical reactions, but also on physical interactions between the polymer chains.The SME properties were quantitatively studied during SMP deployment using DMA. During bending (transformation to the temporary shape), tensile stresses are developed on the sample’s convex side, while compressive stresses are developed on the sample’s concave side. The compressive stresses cause the chains and POSS molecules to become closer to each other. On the other hand, tensile stresses cause the chains and POSS molecules to become farther apart. During the deployment of the samples, as they return back to their permanent shape, the chains and POSS molecules reorient to their original position before bending. The difference in the chains and POSS molecules position before bending and after deployment is proportional to the recovery rate value. The higher the recovery rate, the smaller the difference between the original position of the chains and POSS molecules and their position after bending and recovery. The shape recovery decreased when the POSS content was increased for both POSS types. It can be assumed that as the POSS content increased, more POSS molecules were present in the matrix as molecular fillers, which may act as effective chain barriers ,72. Thes®  [®  [DGEBA epoxy monomer   was usedlastics)  containilastics)  containiThe samples were prepared as follows. The epoxy resin, crosslinker, and POSS additive were weighed and transferred into a glass vial. Then, the vial was heated to 80 °C in order to reduce the epoxy resin and POSS additive viscosities, thus allowing efficient mixing; it was shaken vigorously by a vortex shaker for 1 min at 3000 rpm. Then, the mixture was placed in a vacuum oven preheated to 80 °C. Degassing was performed for 8 min at a pressure of less than 10 Torr. Then, the adhesive was casted in an aluminum mold having 70 × 10 × 1.8 mm and 20 × 3.3 × 1 mm cavities. The curing process of the pristine epoxy was adopted from Xie et al. , at 100 e system . Before each measurement, two-point calibration was performed with indium and zinc. The samples for the DSC measurements were weighed by Sartorius SE2 micro-balance (precision of ±0.1 µg); the sample mass was between 40 and 95 mg. Three samples from each EPOSS composition were placed in aluminum crucibles, and the measurements were done under nitrogen atmosphere flowing at 200 mL/min. The DSC investigation was performed at 100 and at 130 °C, see The calorimetric behavior of curing and post-curing processes was studied using DSC 1 STARTg was determined by the midpoint of the step height of the DSC thermogram while heating the cured samples at a heating rate of 10 °C/min. The degree of curing (α) is equal to the ratio of the heat released at time t, H(t), and the total heat released by the curing and post-curing reaction, Htotal (see Equation (1)) [ion (1)) :(1)α(t)=α was calculated from the ratio of the total heat released during the curing and post curing of a particular EPOSS composition to the heat released during the curing and post curing of the pristine epoxy resin.Here, Tg of each composition was obtained from the maximum value of the tan δ versus the temperature curve of three samples for each EPOSS composition. Tan δ (where δ is the phase lag between stress and strain) is calculated from tan δ = E″/E′, where E″ is the loss modulus and E′ is the storage modulus. The crosslinking density, ρ, was calculated using the rubber elasticity theory according to Equation (2) [E′ (MPa) is measured at T = Tg + 30 °C, R is the gas constant, and T is the temperature at T = Tg + 30 °C.The mechanical and thermomechanical properties of the EPOSS samples were characterized using Q800 model DMA (TA Instruments) using three-point bending fixtures. The experiments were performed at a constant strain of 0.1%, a frequency of 1 Hz, and a temperature ramp rate of 3 °C/min from 30 to 130 °C. The tion (2) :(2)ρ and held isothermally for 10 min. Then, the sample was bended to a temporary shape until a strain of mε = 10% was reached. Bending was performed at a strain rate of 5%/min, and the sample was held in its temporary shape isothermally for 20 min. Subsequently, the sample was cooled down to 30 °C at a rate of 3 °C/min while maintaining a constant strain of mε. Afterwards, the force was reduced to 0.001 N, and the sample strain (uε) was measured upon load removal. In the last stage of the cycle, the sample was heated at 5 °C/min up to a temperature of T = Tg + 30 °C, and the SMP returned to its permanent shape. During this stage, the residual strain (pε) was determined, and another heating cycle was performed.The Q800 DMA operating in controlled strain mode was used to quantify the SME of the different EPOSS SMPs. Samples having dimensions of 20 × 3.3 × 1 mm were used for this purpose. Six thermal cycles were performed for each EPOSS SMP composition. First, the sample was heated at 5 °C/min to fR) and recovery (rR) of the SMPs during N consecutive thermal cycles were calculated using Equations (3) and (4), respectively. Fixity is the ability of an SMP to preserve its temporary shape after cooling and unloading. Recovery is its ability to return from the temporary shape to its permanent shape after reheating [The fixity (eheating .(3)Rf(NrV) was determined using Equation (5) [T10 and T90 are the temperatures corresponding to recovery rates (Rrate) of 10% and 90%, respectively, in the recovery rate curve, and 2ε is the strain of the SMP in its temporary shape and ε(T) is the strain at a designated temperature (T).The recovery process speed (tion (5) :(5)Vr(%mtion (6) :(6)RrateAmine- and epoxide-based epoxy–POSS SMPs  were prepared with various contents of AM–POSS and EP–POSS. The effects of POSS type and content on the SMPs’ thermomechanical and shape memory properties were studied. The curing degree and the crosslinking density of the nanocomposites were derived from DSC and DMA measurements.EP–POSS formed mainly chemical crosslinking. The crosslinking density increased with the increase in the EP–POSS content, which was most likely due to the higher functionality of the EP–POSS molecules compared to the original epoxy resin that it replaced. However, the crosslinking density remained constant as more AM–POSS was added to the system, which indicates the prevalence of the physical crosslinking. This physical crosslinking may be formed through π–π interactions between phenyl groups from the AM–POSS molecules and bisphenol A groups from the epoxy resin. The higher functionality of the AM–POSS, compared to the original crosslinker it replaced, also contributed to the conservation of the crosslinking density, although the degree of curing decreased as more AM–POSS was added to the system.Tg, EP–EPOSS SMPs showed higher storage modulus, i.e., elasticity values, compared to AM–EPOSS. As a result, EP–EPOSS exhibited lower shape fixity values than AM–EPOSS SMPs. EP–EPOSS SMPs had higher crosslinking density and, hence, they exhibited a higher shape recovery than AM–EPOSS SMPs. Both types of EPOSS SMPs showed a certain decrease in recovery speed with the increased POSS content. This is due to an increase of the number of POSS molecules dispersed in the matrix as molecular fillers, which served as effective chain barriers. It is also assumed that the recovery speed of AM–EPOSS SMPs is higher than EP–EPOSS due to its chain structure. It is suggested that the lower amount of chemical bonding and higher amount of physical crosslinking in AM–EPOSS resulted in lower free volume and better thermal properties compared to EP–EPOSS.The addition of a significant amount of POSS to the nanocomposites did not compromise excellent shape memory properties. Above Tg, can be enhanced. Such nanocomposites with high silicon content and excellent shape memory properties are promising candidates for SMP-based space deployable mechanisms.This work presents novel nanocomposite materials with a high content of POSS and effective means to control the SME triggering temperature. It is shown that by choosing a specific POSS type and content, the mechanical properties, either below or above


The influence of pore structure factors on mechanical strength and shrinkage was studied by grey correlation theory, and the results showed that Dm showed positive correlations with strength and fracture energy, with increasing Dm tending to strengthen and toughen the concrete. An increase in fiber content and length was detrimental to reducing the drying shrinkage strain. In the transition pore region, the fractal dimension (Dt) at diameters ranging from 20 to 50 nm and shrinkage strain exhibited a highly linear relation. These results merit careful consideration in macro-property evaluation by using the pore surface fractal dimension in a specific region instead of the whole region. Finally, grey target theory was applied to evaluate the rank of the mechanical strength and shrinkage of concrete, and the results showed that the overall properties of concrete with a BF length of 18 mm and a BF content of 0.06% ranked the best.In this study, we focused on exploring the correlations between the pore surface fractal dimensions and the pore structure parameters, strength and shrinkage properties of basalt fiber-reinforced concrete (BFRC). The pore structure of BFRCs with various fiber contents and fiber lengths was investigated using mercury intrusion porosimetry (MIP) measurements. Through Zhang’s model, the fractal characteristics of BFRCs in the whole pore size range and in different pore size ranges were calculated from the MIP test data. The results showed that the addition of BF increased the total porosity, total pore volume and pore area but decreased the average pore diameter, indicating that BFs refined the pore structure of the concrete. BFRC presented obvious fractal characteristics in the entire pore-size range and individual pore-size ranges; generally, the fractal dimension increased with increasing fiber content. Moreover, correlation analysis suggested that the fractal dimension of BFRC in the whole pore-size range (FD) was closely related to the fractal dimension in the macropore region (D Concrete is a brittle material with low tensile strength. Concrete structures are exposed to the natural environment and subjected to the coupling effect of environmental factors and load during their whole service life. Shrinkage-induced cracks spread and expand rapidly under repeated loading, which significantly lowers the load-bearing capability and fatigue performance of concrete . Thus, sTo reduce crack sensitivity and solve the limitation of quasi-brittle fractures in concrete, the utilization of fiber in concrete has attracted extensive attention in recent years. Fiber-reinforced concrete (FRC) has been developed into a new type of concrete that has been successfully applied in engineering. The main reason can be attributed to its excellent properties, such as tensile strength, crack and shrinkage resistance, and fracture toughness, which also substantially improves the durability of concrete. Researchers have engaged in extensive efforts to study the effects of different types of fibers on cracking, shrinkage resistance and toughness properties. Steel fiber and polypropylene fiber are reinforcement materials that are highly valued by researchers because of their outstanding cracking resistance and enhanced tensile strength in concrete ,4,5,6,7.Basalt fibers are made by melting and drawing basalt rocks; there are no harmful gases emitted during the whole manufacturing process, which is why basalt fiber is often called “green fiber”. Owing to its apparent advantages, such as environmental friendliness, cost effectiveness, light weight, high modulus, and excellent thermal and chemical stability ,10,11,12The actual pore structures of concrete are complex and have extremely irregular morphologies; therefore, some researchers believe that the pore structure cannot be wholly characterized by using traditional parameters such as porosity, average pore diameter, and pore volume ,22. FracThe addition of fibers to the concrete inevitably introduces pores and increases the interface area, which may simultaneously change the fractal characteristics of pore structures. As mentioned before, many studies have been performed to investigate the mechanical properties, fracture performance, shrinkage and durability of fiber-reinforced concrete. Some studies have also been conducted to explore how basalt fiber affects the pore structure parameter and have further established the simple relationship between porosity, average pore size and macro properties ,29,30. H3, two sizes of crushed stone (maximum size of aggregate of 9.5 mm and 19 mm) , river sand  with fineness modulus of 2.6, superplasticizer  with 26% water reduction rate, water, and basalt fiber . The concrete mix proportion of concrete can be found in 3. For BFRCs, the content of superplasticizer is 0.0125 of the mass of cement, which is 5.49 kg/m3. It should be mentioned that all mixture had achieved the target slump. Basalt fiber reinforced concrete (BFRC) was prepared by the following ingredients: Grade 42.5 ordinary Portland cement  with the density of 3011 kg/mAll solid ingredients including sand, coarse aggregate and half mass of basalt fiber were first mixed for 60 s in forced concrete mixer , then pour out rest of basalt fiber and cement into a blender and remixed for 60 s. The next step was to add water and water reducer, and then, the mixture was remixed for 120 s. Casted the mixture into molds and vibrated on a high-frequency vibration table. Finally, moved specimens into environment room with the condition of 20 ± 5 °C temperature and 95% humidity for curing. The diagram of test program is given in 3 were used for compressive strength test after curing 28 days. Each series of BFRCs had three specimens. The compressive strength test was loaded through a 5000 kN electro-hydraulic servo pressure testing machine , and the compressive strength was calculated by Equation (1).cf means compressive strength (MPa), F represents for ultimate load (N), A is the bearings area (mm2).Control and BFRCs specimens were prepared according with Chinese standard GB/T50081-2002. Cube specimens of 150 × 150 × 150 mm3 were prepared, tests were conducted using a YES-300B tester  with 0.05 MPa/s to 0.08 MPa/s loading rate. Each series of BFRCs had three specimens. The calculation of flexural strength of concrete is according to Equation (2), which listed as follows:fF means flexural strength (MPa), F represents for ultimate load (N), L is the distance between supports (mm), b and h are the width and height of concrete specimens (mm), respectively. In this study, L is set as 300 mm, and both b and h are 100 mm.Chinese standard GB/T50081-2002 also was adopted for flexural strength test. According to standard, prisms specimens with size of 100 × 100 × 400 mmIn this study, MIP was adopted to determine the pore size distribution of the control concrete and BFRCs. After curing 28 days, one prims specimen with 5 mm height of each concrete was selected, then take out a piece of specimens with a size of 10 mm × 10 mm × 5 mm for MIP test. To ensure the accuracy of the data, the aggregate part should be avoided. The pore structure tests were carried out by using an Autopore IV 9500 mercury porosimeter produced by Micromeritics Company, Norcross, Georgia, America.3 were tested by a three-point bending test  based on The International Union of Laboratories and Experts in Construction Materials, Systems and Structure (RILEM), control concrete and each series of BFRCs has three specimens. A notch with a depth of 20 mm and a thickness of 2 mm was made in the midspan, as shown in fG) was determined by using the following formula (Equation (3)) given by RILEM 50-FMC Technical Committee.W0 is the area under the load-CMOD curve (N/mm), mg is the self-weight of the specimen (kg), δ0 is the maximum mid-span displacement (mm), b and h are the width and height of the beam (mm), respectively. a0 is the height of notch (mm).Twenty-one notched beams with size of 100 × 100 × 400 mm3 prisms of each BFRC were prepared for free drying shrinkage test .Three 100 × 100 × 400 mmFor continuous monitoring the shrinkage strain of concrete as curing time increase, voltage data collector was matched with displacement meter, as can be seen in 3. Before the SEM test, cube samples need to be dried, dusted, and the gold sprayed on their surface. We took three pieces of samples from each series of concrete for the SEM analysis.The cube test samples were taken from the specimens after strength test with size of 1 cmAn MIP test was carried out to investigate the pore structure of concrete with various contents and lengths of BF. The pore size distribution curves of each BFRC sample and the control concrete are shown in The behavior trend of pore size distribution of the control and BFRCs with different BF lengths are depicted in The percentage of specific BFRC pore volume is given in The trends of variations in the pore structure with the BF length are not similar to those in concrete with different BF contents. With increasing BF length, the porosity of the BFRCs first decreases and then increases. As expected, the porosity of BF-24-0.06% is higher than that of other BFRCs with the same fiber content. Notably, BF-24-0.06% also shows a larger average pore size, which is approximately 3 times higher than that of BF-12-0.06%. Combined with the pore size distribution, it can be deduced that refinement of concrete pore structure is weakened when BF with a length of 24 mm is added.nW is the cumulative intrusion work, Wn = iP (psia) and iV (mL/g) are the mercury intrusion pressure and the intrusion volume at the ith intrusion of mercury; nV (mL/g) is the accumulative intrusion volume, nr (nm) is the pore diameter, and C is the model constant. According to Equation (4), after calculating sD is determined as the slope value of the fitting line.To quantitatively assess the parameter for the pore size distribution of concrete matrices by BF, the fractal dimensions of the pore surfaces were calculated based on the thermodynamic method proposed by Zhang et al. ,36. The The results of the surface fractal dimension (FD) of different BFRCs are presented in m < Dc < Dt <Dg, indicating that the smaller the pore size is, the more complex the pores are. In Regions I and II, Dm and Dc of the control concrete are smaller than those of the BFRCs. However, in Regions III and IV, the Dt and Dg of the control concrete are higher than 3.0, which is not in conformity with the basic assumption of Zhang’s model. Some researchers attributed this phenomenon to the existence of ink-bottle pores. In the investigation of Yu et al. [g between BFRCs is not as obvious as Dm and Dc. This can be ascribed to the fact that the properties of gel pores are closely related to the hydration products [g values of BFRCs are close to each other.Moreover, by using Zhang’s model, Kim et al. , Zhu et u et al. , the resu et al.  also repproducts . BF is am, Dc, average pore diameter (APD), total pore volume (TPV) and total pore area (TPA). The results are presented in In order to obtain the interrelationship among pore parameters, correlation analysis was performed among FD, porosity with different pore size, Dm, and the correlation coefficient between FD and Dm is the highest. With an increase in FD, the average pore diameter decreases, indicating that the smaller the pore size is, the higher the degree of complexity for the pore structure. In this study, the most likely apertures of the control concrete and BFRCs are all macropores, suggesting that macropores are widely dispersed in the whole pore structure. This could be ascribed to the strong correlation between FD and Dm. Moreover, it can be seen that the gel pores and capillary pores have a good correlation. The reason might be related to the fact that a similar behavior can be observed in gel pores and capillary pores with increasing fiber length and content. Another observation is that macroporosity displays an evident relationship with TPV. This makes sense, as more macropores indicate more TPV.The relationship between FD and total porosity is not significant, implying that porosity cannot represent the complexity of pore structure. FD presents a close relationship with APD and DThe obtained compressive and flexural strengths of the specimens with four different BF lengths and contents are displayed in By analyzing the flexural strength data of the BFRCs in The applied load versus CMOD curves for BFRC notched specimens are shown in f) of the concrete. From the f value compared to BFRCs with the same BF length. This value is 65.17% higher than that of the control concrete. It can be seen from f increase with increasing fiber length. A further increase in fiber length (24 mm) has no contribution but causes an apparent decrease in Gf. Kabay [The addition of BF considerably increases the peak load, maximum deflection and fracture energy  = i = i(k) = Transfer the data series to the dimensionless form, the formula to normalize the data is as follows: YThe correlation coefficient was obtained by the following equation: The average correlation coefficient can be calculated by the following equation: To investigate the degree of correlation between pore structure factors and macro properties of BFRC, the grey correlation analysis was applied. The specific calculation steps are as follows:iγ). It can be seen that for flexural strength, compressive strength and fracture energy, the order of the grey correlation coefficient is Dm > FD > another factor. Especially in the coefficient of strength and Dm, the iγ of Dm is over 0.9. From the analysis in m of the BFRCs, as shown in m, and the correlation coefficients are relatively high. The strength is mainly determined by macropores and gel pores, and the influence of macropores is more notable. Dm reflects the complexity of the entire macropore; therefore, it is reasonable to find that Dm exerts a higher R2 with strength compared with FD. For drying shrinkage, the highest iγ between shrinkage strain and pore factors is the transition porosity; however, it is obviously smaller than that of iγ between Dm and strength. As mentioned above, the porosity of small transition pores (20–50 nm) was closely related to drying shrinkage, and the Dt with diameters ranging from 20 to 50 nm was calculated by using Zhang’s model, as shown in t (20–50 nm) and shrinkage strain is also given in t is a reflection of a large transition pore content, which also means that a large water loss reduces the concrete weight. Thus, a high shrinkage strain could be expected. These results also reveal that the proposed approach may be a rational and effective way to evaluate the properties of BFRCs by using fractal dimensions calculated in different pore size ranges.The macro properties of the control concrete and six kinds of BFRCs are displayed in The specific steps are as follows:cf is the compressive strength, ff is the flexural strength, F is the fracture energy, ε is the drying shrinkage strain. (1) Define the index sequence as: (2) As the compressive strength, flexural strength and fracture energy are the maximum polarity, while drying shrinkage strain is the minimum polarity, the standard model is: (3) Dimensionless parametrization: (4) The distance to target: The addition of basalt fiber (BF) decreased the coarseness of the pore size and refined the pore structures. As the fiber content increased, the total porosity and total pore volume increased, whereas the average pore diameter decreased. When the fiber length ranges from 6 mm to 18 mm, as the fiber length increases, these parameters present the same tendency. BFs diminished the macropore content, and the more BFs contained in the sample, the fewer macropores in the concrete.g  of the control concrete exceeded 3.0.BFRCs presented obvious fractal characteristics in the whole pore-size range; compared with control concrete, BFRCs increased the fractal dimension, indicating that the addition of BF increased the complexity of the surface topography. Moreover, the fractal analysis of BFRCs in four pore size ranges showed that BFRCs exhibited obvious fractal characteristics in every individual region. The larger the pore size is, the larger the fractal dimension. In the gel pore region, the Dm and the average pore diameter (APD). Dm presented a positive correlation with FD, while APD exerted a negative correlation with FD.Through correlation analysis, the fractal dimension in the entire pore-size range (FD) was closely related to the DThe presence of basalt fibers increased the flexural strength of plain concrete, while compressive strength showed no significant growth. As the fiber content increases, the flexural strength increases. Compared with the plain concrete, the compressive and flexural strength of concrete reinforced by 18 mm long BFs increased by 6.89% and 18.62%, respectively. When the fiber length was increased to 24 mm, an obvious drop in flexural strength was observed. The addition of BFs could remarkably increase the fracture energy of concrete; as the BF dosage increased, the peak load value and displacement increased. A significant drop in peak load and fracture energy was observed in BF-24-0.06% due to its uneven fiber distribution.m presented a stronger correlation with strength and fracture energy (Gf) than other pore factors, and the relationship between drying shrinkage strain and fractal dimension in the small transition pore region (20–50 nm) presented a highly positive linear function. Thus, Dm and Dt could be addressed as representative pore structure parameters to predict the strength and drying shrinkage of BFRC.Grey correlation analysis was applied to indicate the precedence among pore structure factors in affecting the mechanical strength and shrinkage of the concrete. The results showed that DFrom the evaluation result with grey target theory, the overall properties of BF-18-0.06% ranked the best, followed by BF-12-0.07% and BF-12-0.06% in sequence.In this experimental study, the pore structure of basalt fiber reinforced concrete (BFRC) with various fiber lengths and contents was characterized by the MIP test, and the pore surface fractal dimensions of the BFRCs in the whole pore size range and in different pore size ranges were calculated using Zhang’s model. The relationship between the pore structure parameters and the fractal dimension was analyzed. In addition, the effects of fiber content and fiber length on strength, fracture properties and shrinkage (BFRC) were evaluated, and their correlations with surface fractal dimensions were also evaluated. The following conclusions have been drawn:


Background: Systemic antibiotic prophylaxis is frequently prescribed by dentists performing dental implant surgery to avoid premature implant failure and postoperative infections. The scientific literature suggests that a single preoperative dose suffices to reduce the risk of early dental implant failure in healthy patients.Material and Methods: A systematic review was made based on an electronic literature search in the PubMed-Medline, Embase, Web of Science, Scopus and Open Gray databases. The review addressed the question: “which antibiotic prophylaxis regimens are being used in dental implant surgery in healthy patients according to survey-based studies?” The identification, screening, eligibility and inclusion phases were conducted according to the PRISMA statement by two independent reviewers. The following data were collected: country, number of surveyed dentists, number of dentists who responded (n), response rate, routine prescription of antibiotic prophylactic treatment , prescription regimen  and antibiotic choice (first and second choice). Cohen’s kappa coefficient (k) evaluated the level of agreement between the two reviewers. The analysis of risk of bias was performed follow the Joanna Briggs Institute checklist for observational studies. A descriptive statistical analysis was performed to calculate total target sample, sample size and total mean.Results: A total of 159 articles were identified, of which 12 were included in the analysis. Two thousand and seventy-seven dentists from nine different countries on three continents were surveyed. The median response rate was low and disparate between studies. About three-quarters of the surveyed dentists claimed to routinely prescribe systemic antibiotic prophylaxis for dental implant surgery. The prescription regimen was perioperative, postoperative and preoperative, in decreasing order of frequency. The most frequent first choice drug was amoxicillin, with amoxicillin-clavulanic acid as second choice.Conclusions: A majority of dentists from different countries do not prescribe systemic antibiotic prophylaxis for dental implant surgery following the available scientific evidence and could be overprescribing. Efforts are needed by dental educators and professionals to reduce the gap between the use of antibiotic prophylaxis for dental implant surgery as supported by the scientific evidence and what is being done by clinicians in actual practice. According to the World Health Organization (WHO), the overprescription of antibiotic drugs and the derived antimicrobial resistances constitute one of the most pressing public health problems in the world today . In turnAccording to a systematic review of qualitative studies by Dental implants are currently a routine treatment, having demonstrated their long-term success ; as a reEarly dental implant failure occurs approximately in 2% of all cases and is characterized by a lack of osseointegration of the implant . It has Systemic antibiotic prophylaxis has been used to reduce the risk of early implant failure and local infections around dental implants . Such prRecent studies have concluded that the administration of systemic antibiotics does not significantly reduce early implant failure in simple implant surgeries (defined as surgeries without broad flaps or simultaneous bone regeneration) in healthy patients . MoreoveHowever, several systematic reviews and meta-analyses  have proThe first and most important step in designing effective interventions to improve prescription practice is to identify and understand antibiotic prescription and its modulating factors in dental implant surgery . The preWe conducted a systematic review of the prescription of antibiotic prophylaxis for dental implant surgery as evidenced by survey-based studies according to the PRISMA-P  statement .• Patient (P): healthy patients• Intervention (I): dental implant surgery• Outcome (O): prophylaxis, prescription, habit, use or attitude• Study design (S): survey, questionnaireThis systematic review was based on the following PIOS question: “which antibiotic prophylaxis regimens (O) are being used in dental implant surgery (I) in healthy patients (P) according to survey-based studies (S)?” The search strategy was based on the following keywords:The identification phase based on the search strategy in several databases was updated on 10 May 2020. For the PubMed-Medline search we used the medical subject heading (MeSH) terms (and their entry terms) and non-MeSH terms. The Embase search in turn was based on Emtree terms and their synonyms, and non-Emtree terms. The Web of Science and Scopus databases were also consulted. A search of the gray literature was also performed in Open Gray to include articles published in non-indexed journals or to retrieve a larger number of studies. Furthermore, a manual search was made of the references of the articles retrieved by the previous search strategies. The search strategy corresponding to each database is indicated in The titles and abstracts were read in the screening phase to eliminate articles unrelated to the study objective and duplicate articles. Full-text reading was subsequently made in the eligibility phase to select studies according to the inclusion/exclusion criteria. We included studies in which antibiotic prophylaxis in dental implant surgery was the reason for prescription, without language or date of publication restrictions. Experimental studies or database research studies were excluded, as were studies involving pregraduate dental students, articles lacking information about the prescription regimens , and studies lacking information about the antibiotic of choice.In the case of studies providing information on different dental procedures, only antibiotic prescription referred to dental implant surgery was considered. In addition, if the type of implant surgery was detailed , data were recorded referred to antibiotic prescription for single implants at mature bone sites with flap elevation. In survey-based studies involving some type of training or educational intervention, the data prior to such intervention were collected.The screening and eligibility phases were processed in duplicate by two independent reviewers (JCBM and DPO). In the case of disagreement between the reviewers in any phase, a third reviewer (MPD) was consulted. Cohen’s kappa coefficient (k) was used to assess the level of agreement between JCBM and DPO.The following variables were collected for each included article: author, year of publication, country, target sample, number of dentists who respond (N), response rate (RR), routine prescription of antibiotic prophylaxis , prescription modulating factors, prescription regimen  and antibiotic of choice (first and second choice drug).A critical appraisal tool for use in systematic reviews addressing questions of prevalence derived from the Joanna Briggs Institute checklist  was usedA descriptive statistical analysis was performed using the SPSS version 26.0 statistical package, with calculation of the total target sample, sample size and total mean.The present systematic review was performed according to the PRISMA flow diagram . A totalThe results of the included studies are summarized in The target sample was 6,417 dentists, though one study  failed tThe surveyed dentists were from nine different countries on three continents. Six studies corresponded to four countries in Europe: Sweden , Spain  Italy R and The A total of 77.1% of the surveyed dentists claimed to routinely prescribe antibiotic prophylaxis in healthy patients undergoing dental implant placement. In turn, 8.9% only prescribed antibiotics depending on prescription modulating factors. Fourteen percent claimed to not prescribe antibiotic prophylaxis in any situation .Different prescription modulating factors were recorded in different studies: three clinical factors corresponding to patient conditions, five clinical factors regarding the surgical procedure and eight non-clinical factors. As clinical modulating factors corresponding to the patient conditions, we found past periodontal disease , smokingThe distribution of prescription regimens proved heterogeneous both within and between studies. Perioperative prescription was the most frequent regimen (50.4%), followed by exclusive postoperative prescription (32.2%) and finally exclusive preoperative prescription (17.4%). The prescription regimens were seen to vary considerably even between studies from one same country .Regarding the antibiotic of choice , amoxiciRegarding the analysis of risk of bias , one of The main objective of the present systematic review was to investigate current trends in antibiotic prescription behavior among dentists of different countries performing dental implant surgery, according to survey-based studies.The RR varied greatly between studies (in a range of 15–100%), and even within the same country. This could be due to the different sampling methods used. Although the surveys were online in all the studies except one , the wayMost of the surveyed dentists claimed to routinely prescribe systemic antibiotic prophylaxis. Several studies discerned between routine and conditioned prescription depending on the medical conditions of the patient and the complexity of the intended procedure . RegardiAccording to the scientific literature, a single preoperative antibiotic dose of amoxicillin 1 h before surgery could be useful to reduce early dental implant failure. Perioperative and exclusive postoperative antibiotic prophylaxis have demonstrated results equivalent to exclusive single-dose preoperative prophylaxis in relation to early implant failure . Thus, tIn all the included studies, the first choice antibiotic corresponded to the penicillin family. The most frequently prescribed first choice antibiotic was amoxicillin , followeThe discrepancy between the prescription of antibiotic prophylaxis for dental implant surgery in healthy patients according to the survey-based studies and optimal prescription as suggested by the available evidence could be contributing to the development of antimicrobial resistances , and mayIn the present systematic review, different types of surveys were used to ask the dentists about their preferences regarding the prescription of antibiotic prophylaxis in dental implant surgery. Two main types of surveys were identified, whose original designs corresponded to Based on the findings of the present systematic review, incorrect and unjustified antibiotic prescription practices in dental implant surgery in healthy patients are observed. The publication of specialized clinical guidelines and continuous and focused training for prescribers are needed. Defective antibiotic prescription and the indiscriminate use of such drugs can produce serious bacterial resistance problems.As a limitation of the present systematic review, mention must be made of the fact that the number of countries and professionals evaluated in relation to the prescription of antibiotic prophylaxis was limited. As a strength, however, the study evidences that understanding of the use and prescription of antibiotic prophylaxis for implant surgery among dentists should be strengthened. The results of our systematic review were based on studies characterized by moderate and high risk of bias, so the results should be interpreted with caution.As recommendations, the calculation and selection of representative samples, and the taking of confounding factors into account, may improve the quality of future studies. Moreover, scientific associations could develop a common and proven survey for future studies based on the best available questionnaires and possible improvements.According to cross-sectional survey-based studies, a majority of dentists from different countries do not prescribe systemic antibiotic prophylaxis for dental implant surgery following the available scientific evidence and could be overprescribing. Efforts are needed by dental educators and professionals to reduce the gap between the use of antibiotic prophylaxis for dental implant surgery as supported by the scientific evidence and what is being done by clinicians in actual practice.