MET amplification is one of the resistance determinants after EGFR-TKI therapy in EGFR mutant NSCLC. In this study, we evaluated the emergence of MET amplification after EGFR-TKI treatment failure. The median progression-free survival associated with the most recent EGFR-TKI treatment was shorter in MET amplification-positive patients than in negative patients. Smoking history and less intracranial progression are associated with MET amplification. Suboptimal responses with previous EGFR-TKI are associated with MET amplification. Proper MET amplification screening for therapeutic targeting is needed.EGFR) mutant non-small cell lung cancer (NSCLC) ultimately acquire resistance to EGFR tyrosine kinase inhibitors (TKIs) during treatment. In 5–22% of these patients, resistance is mediated by aberrant mesenchymal epithelial transition factor (MET) gene amplification. Here, we evaluated the emergence of MET amplification after EGFR-TKI treatment failure based on clinical parameters. Materials and Methods: We retrospectively analyzed 186 patients with advanced EGFR-mutant NSCLC for MET amplification status by in situ hybridization (ISH) assay after EGFR-TKI failure. We collected information including baseline patient characteristics, metastatic locations and generation, line, and progression-free survival (PFS) of EGFR-TKI used before MET evaluation. Multivariate logistic regression analysis was conducted to evaluate associations between MET amplification status and clinical variables. Results: Regarding baseline EGFR mutations, exon 19 deletion was predominant (57.5%), followed by L858R mutation (37.1%). The proportions of MET ISH assays performed after first/second-generation and third-generation TKI failure were 66.7% and 33.1%, respectively. The median PFS for the most recent EGFR-TKI treatment was shorter in MET amplification-positive patients than in MET amplification-negative patients . Multivariate logistic regression demonstrated that a history of smoking, short PFS on the most recent TKI, and less intracranial progression were associated with a high probability of MET amplification . Conclusions: Our results demonstrated the distinct clinical characteristics of patients with MET amplification-positive NSCLC after EGFR-TKI therapy. Our clinical prediction can aid physicians in selecting patients eligible for MET amplification screening and therapeutic targeting.Objectives: Patients with epidermal growth factor receptor ( EGFR) gene mutations are defined as an important targetable molecular subset [EGFR and conventional EGFR mutations (exon 19 deletion and L858R substitution), exhibit robust activity against T790M-mutant NSCLCs, showing progression after first-line EGFR-TKI therapy, with a progression-free survival (PFS) of 8.5 months and a prolonged PFS of 17.2 months in a upfront trial [EGFR mutation and coexisting genetic alteration might likely justify resistance to TKIs treatment. Different studies have assessed that the uncommon EGFR mutation and concurrent presence of mutation provide worse prognosis in EGFR-positive NSCLC patients treated with first-, second-, and third-generation TKIs [Patients with non-small cell lung cancer (NSCLC) with epidermal growth factor receptor  or mutation screening after EGFR-TKI failure.Mesenchymal epithelial transition factor (MET) is a receptor for hepatocyte growth factor (HGF) in mammalian cells and transduces growth factor signals to downstream mitogen-activated protein kinase and phosphatidylinositol 3-kinase pathways through tyrosine kinase activity . AberranGFR-TKIs ,12. Resill cases . Interesmutation ,15. HoweEGFR, ALK receptor tyrosine kinase (ALK), ROS proto-oncogene 1 (ROS1), RET, B-Raf proto-oncogene, and human epidermal growth factor receptor 2. During analysis of the “long-tail” distribution patterns of mutations, previous studies have reported distinct clinicopathological characteristics of each genotype. For example, EGFR-mutant NSCLC is highly prevalent in never-smokers and Asian populations [ALK rearrangement is associated with young patient age at diagnosis, signet ring cell pathology, and bronchioalveolar involvement pattern [MET-amplified NSCLC after EGFR-TKI failure have not been evaluated, and no predictive factors for MET amplification have been reported.NSCLC comprises heterogeneous molecular subtypes harboring mutations in various oncogenes, including ulations . ALK rea pattern . These f pattern . HoweverMET ISH assays on rebiopsied tumors. We compared the clinicopathological parameters and therapy responses for the previous EGFR-TKI therapy between patients with MET-amplified and non-MET-amplified NSCLC. We ultimately aimed to develop a clinical prediction method for MET amplification after EGFR-TKI failure, which is an essential step for focused MET screening and subsequent therapeutic MET targeting in patients.Accordingly, in this study, we retrospectively analyzed 186 consecutive patients with EGFR-mutant NSCLC who underwent EGFR-mutant NSCLC who progressed on EGFR-TKI therapy and underwent MET ISH assays at Yonsei Cancer Center between April 2004 and March 2019. All patients received EGFR-TKI therapy, and post-treatment tumor biopsy was performed after documented progression. The clinicopathological data for the patients, including age, sex, smoking status, type of EGFR mutation, metastatic site, line of EGFR-TKI therapy, type of EGFR-TKIs used, and PFS on previous EGFR-TKI, were collected by electronic medical chart review. Informed consent for MET ISH analysis and use of data was obtained at the time of rebiopsy. This study was approved by the institutional review board of Severance Hospital .This study retrospectively analyzed 186 patients with advanced MET ISH assays to the date of death.Chest computed tomography (CT) and abdominal CT were taken every 2–3 months during treatment. Besides regular assessment follow-up, additional imaging was performed according to the physician’s intention. The response to EGFR-TKI treatment was radiologically assessed according to the Response Evaluation Criteria in Solid Tumors, version 1.1. The objective response rate (ORR) was defined as the proportion of patients with complete response (CR) or partial response (PR), and the disease control rate (DCR) was defined as the proportion of patients with CR, PR, or stable disease. Progression-free survival (PFS) was defined as the time from the start of EGFR-TKI treatment to disease progression or death. Overall survival (OS) was defined as the start of TKI treatment initiation to the date of death. In order to characterize OS based on treatment lines and TKIs, we also measured OS from the date of EGFR mutation status was evaluated using a PANA Mutyper detection kit. The MET amplification status was assessed using MET VENTANA dual probe sliver ISH assays, defining a MET/CEP7 signal ratio of greater than or equal to 2 or a MET average copy number in at least 50 enumerated cells of greater than or equal to 5 as MET amplification positive [The diagnosis of NSCLC with non-squamous histology was confirmed by pathological and radiological examination. In all patients, the positive .MET amplification-positive and -negative patients using chi-squared or Fisher’s exact tests as appropriate. Continuous variables were compared using Student’s t-tests. The PFS and OS were estimated using Kaplan–Meier curves, and subgroups were compared using log-rank tests. Logistic regression analyses were done to identify significant clinical factors predicting the emergence of MET amplification after EGFR-TKI therapy in the study cohort. Statistical analyses were performed with Statistical Package for Social Sciences  version 23.0 for Windows and GraphPad Prism version 8.0 . Two-sided p-values of less than or equal to 0.05 were considered significant.The categorical parameters were compared between EGFR-mutant NSCLC were enrolled; the majority of patients were women (62.4%), and the median age was 61 years . Most of the patients were never smokers (67.2%), and 0.0 pack-years of smoking was the median for the whole patient population. Regarding primary EGFR mutation status before MET ISH biopsy, the existence of exon 19 deletion mutation was predominant (57.5%), followed by L858R mutation (37.1%). Other mutations including Exon 20 insertion (p.A767_V769dup) (0.5%), G719X (1.1%), L861Q (2.2%), S768I (1.1%), and G179S/L861Q (0.5%) also existed. Almost all patients in the third-generation TKI cohort, except for six cases, had T790M mutation coexistence at the point of MET ISH assay owing to label use of third-generation TKIs in Korea. The six cases excluded from this regulation included one with off-label use of osimertinib, one with use of rociletinib during clinical trials (without T790M mutation), and three with use of mavelertinib during clinical trials (without T790M mutation). The proportions of MET ISH assays performed after first/second-generation  or third-generation  TKI failure were 66.7% and 33.3%, respectively. The proportions after failure of first-line and later-line EGFR-TKIs were 44.1% and 55.9%, respectively. At baseline, 78 (41.9%) patients had brain metastasis. At the time of MET ISH screening, 64 patients had progression of existing intracranial lesions, and 39 patients progressed with new lesions in the brain. Additionally, 8.1% (n = 15) of patients had liver metastasis at baseline. Eleven patients showed progression of existing lesions, and 28 patients had new liver metastasis at the time of rebiopsy.In total, 186 patients with advanced MET amplification was identified in 30 (16.1%) of 186 patients. Patient characteristics based on MET amplification status are shown in p = 0.013), previous TKI generation (p = 0.034), previous TKI line (p = 0.003), and intracranial progression at the time of TKI failure (p < 0.001) showed significant differences between the two groups. By the time of data lock (4 March 2021), 133 deaths (71.5%) had occurred, and 53 patients (28.5%) were alive. The median follow-up duration for all patients was 65.4 months.MET ISH assays) for the total population was:The median OS . However, it was difficult to interpret the actual prognostic effects of MET status because some patients (n = 23) were enrolled in MET inhibitor clinical trials.11.6 months  A. The meMET-positive group than in the negative group . However, in the third-generation TKI group, there were no significant differences in PFS , and only similar trends were observed  B. Becausobserved .MET amplification. Univariate analysis showed that smoking status, TKI generation, lines of EGFR-TKI therapy, PFS of the most recent TKI, and brain metastasis status at presentation were significant predictive factors. However, multivariate analysis considering all covariables identified only smoking status , PFS of most recent TKI , and intracranial progression status  as significant variables. The presence of smoking history, short PFS on latest TKI, and no intracranial progression at EGFR-TKI failure were associated with a high probability of MET amplification emergence.The T790M mutation was not included in the logistic regression analysis. The reason is that in the case of acquiring the T790M mutation, since most of the patients were administered the 3rd generation TKI, multicollinearity occurred between the two variables.MET amplification (n = 30) based on the most recent TKI outcomes and progression site (p = 0.26). Additionally, the DCRs of the most recent first-/second-generation and third-generation TKIs were 93.3% and 80%, respectively (p = 0.29). Regarding the PFS of the most recent TKI, there were no differences between the first/second-generation group and the third-generation group . The treatment PFS of the most recent TKI and the best responses are shown in We further investigated the characteristics of patients with ion site . The ORRMET-amplified cancer during progression after EGFR-TKI therapy. The most common site of progression was primary lung lesions (n = 23), followed by intrathoracic lesions, which were indicative of lymph node, pleura, and secondary lung metastases (n = 17). Among the biopsy sites from which MET-amplified tissue was obtained, lung lesions were the most frequent site for rebiopsy (n = 17), followed by the liver because of its easy accessibility. The intrathoracic lymph node, extrathoracic lymph node, and skin were the rest of the sites for rebiopsy, as shown in There was no metastatic tropism of EGFR mutant status, are indicative of the efficacy of EGFR-TKI therapy in advanced NSCLC and are now routinely evaluated in clinical practice [Predictive genomic markers, particularly practice . Additiopractice ,22. Becapractice . Howeverpractice ,25.MET-positive patients was 16.1%; in the first/second-generation and third-generation TKI failure groups, 12.1% and 24.2% of patients were positive for MET, respectively, consistent with previous studies [EGFR mutant lung cancer cohort, this consistent proportion of MET amplification as determinant of resistance makes it reasonable to find the enriched population to evaluate. To the best of our knowledge, this is the first MET ISH study to confine its scope to patients who developed resistance to prior EGFR-TKI failure, which we commonly encounter in our clinical practice. Although first-line osimertinib treatment is the standard of care in many countries, in Korea, it is not often selected as 1st line TKI because it is not covered by the National Insurance Service of Korea health insurance. Thus, this point should be considered because it is unclear whether the characteristics of the present patients are predictive of MET amplification in resistance after first-line therapy in osimertinib.In our study, the proportion of  studies ,24,25,26MET positivity occurred more frequently in ever-smokers who had a history of tobacco use than in never-smokers. Typically, other driver mutations  of lung cancer tend to occur in never-smokers [MET exon 14 mutation [MET amplification [MET exon 14 mutations whose smoking statuses were not known would be mostly never-smokers owing to their low tumor mutation burden [MET amplifications is needed, considering real-world data, it is reasonable to screen patients with a history of tobacco use for MET amplification.In this study, -smokers ,27,28. Smutation ,30 and ification . Howevern burden . AlthougALK-positive lung cancer have a higher incidence of brain metastasis, whereas patients with ROS1-positive lung cancer have a lower incidence [MET-positive lung cancer after previous TKI failure. A recent study in a treatment-naïve population showed that there were no differences in the presence of brain metastasis between MET-high and MET-low patients, as defined by copy number gain [MET amplification than in patients without amplification. Our findings suggested a need to identify pathways other than MET amplification as resistance mechanisms associated with EGFR-TKI failure in patients having brain metastasis.Lung cancer easily metastasizes to the brain; indeed, 10–50% of all patients with lung cancer develop brain metastases during their disease course ,33. Morencidence ,35,36. Tber gain . HoweverMET amplification compared with that in patients without amplification. Some reports have shown that various oncogenic MET-driven cancers are associated with poor prognoses [MET amplification. A recent study of treatment-naïve EGFR mutant lung cancer showed that there were no differences in time to treatment failure (TTF) between two groups distinguished according to MET copy number. Instead, patients with MET amplification showed short TTF and poor outcomes  [MET amplification. Overall, we believe that it is reasonable to perform MET ISH in patients who show suboptimal responses to previous EGFR-TKIs in practice.Last but not least we found a significant tendency toward a shorter PFS for the most recent TKI in patients with rognoses ,39,40. H months) . AlthougMET amplification, mutation, and overexpression have not yet been confirmed when collectively applied as predictive markers for MET-targeting therapy. Owing to failed results of clinical trials in which patients with MET-overexpressing tumors, measured by immunohistochemistry of MET protein, were enrolled [MET-TKI clinical trials is gene amplification [MET mutations are generally thought to be mutually exclusive with mutations in other major lung cancer drivers and have not been shown to be associated with acquired resistance to EGFR-TKI therapy [MET amplification [MET ISH results for EGFR-TKI-resistant lung cancer have clinical relevance in routine practice.Clear-cut relationships between enrolled , the prefication ,42. In a therapy . Becausefication ,45 and ofication  are confMET analysis data in patients with lung cancer who developed resistance after EGFR-TKI therapy. However, there are still several limitations to this study. Given the retrospective nature of the study and the heterogeneity of the real world, this study was subject to potential biases. Additionally, because of the low discovery rate of MET positivity and the diversity of treatments, it was difficult to perform well-controlled analyses. Therefore, additional studies based on stratification of the generation of EGFT-TKIs and line of therapy should be conducted.This study provided the largest series of MET amplification-positive NSCLC after acquisition of resistance to EGFR-TKI therapy. Although MET amplified NSCLC is rare, our clinical predictions could aid physicians in identifying patients eligible for MET amplification screening and therapeutic targeting. Further efforts are required to standardize the diagnostic method and improve patient access to screening.In conclusion, our results revealed the distinct clinical characteristics of patients with


Daphnia magna to examine the importance of rare and abundant taxa by perturbing its relatively simple microbiota with targeted antibiotics. We used sublethal antibiotic doses to target either rare or abundant members across two temperatures and then measured key host life history metrics and shifts in microbial community composition. We find that removal of abundant taxa had greater impacts on host fitness than did removal of rare taxa and that the abundances of nontarget taxa were impacted by antibiotic treatment, suggesting that no rare keystone taxa exist in the Daphnia magna microbiota but that microbe-microbe interactions may play a role in host fitness. We also find that microbial community composition was impacted by antibiotics differently across temperatures, indicating that ecological context shapes within-host microbial responses and effects on host fitness.Host-associated microbes contribute to host fitness, but it is unclear whether these contributions are from rare keystone taxa, numerically abundant taxa, or interactions among community members. Experimental perturbation of the microbiota can highlight functionally important taxa; however, this approach is primarily applied in systems with complex communities where the perturbation affects hundreds of taxa, making it difficult to pinpoint contributions of key community members. Here, we use the ecological model organism IMPORTANCE Understanding the contributions of rare and abundant taxa to host fitness is an outstanding question in host microbial ecology. In this study, we use the model zooplankton Daphnia magna and its relatively simple cohort of bacterial taxa to disentangle the roles of distinct taxa in host life history metrics, using a suite of antibiotics to selectively reduce the abundance of functionally important taxa. We also examine how environmental context shapes the importance of these bacterial taxa in host fitness. The microbes in and on host organism tissue, collectively referred to as the microbiome, are recognized as having important beneficial impacts for the host. Many functions have been tied to bacterial species in the microbiota, including nutrient acquisition for the host  and immu3–Daphnia magna, a widely used model organism in ecotoxicology  constituting >70% of relative abundance  24), and eratures  and becacrobiota , 27. Here (19°C) , and wheDaphnia microbiota associated with specific host life history traits, we selected antibiotics with different modes of action that could perturb bacterial classes differentially. We used erythromycin (ERY), a macrolide that inhibits bacterial protein synthesis . Only 10 unique ASVs comprised approximately 60% of total abundance . Relative abundance of bacteria in Daphnia magna was significantly impacted by antibiotic treatment . The microbiota was significantly impacted by antibiotic treatments at the class rank , sulfamethoxazole (P = 0.001), and the antibiotic trio (P = 0.001) on microbiota composition  and Sphingomonas  and increases in Microvirga . Erythromycin had 16 differentially abundant ASVs, with an unidentified Chitinophagaceae (ASV 24) and Emticicia (ASV 36) experiencing the greatest fold abundance changes . Treatment with sulfamethoxazole induced changes for 8 ASVs, primarily increasing the abundance of the Chitinophagaceae ASV  and decreasing the abundance of Pedobacter . Treatment with the antibiotic trio impacted the abundances of 19 ASVs, contributing to fold increases of the same Chitinophagaceae  and decreasing the abundance of Caulobacter . In summary, aztreonam reduced the relative abundances of Gammaproteobacteria and some Alphaproteobacteria; erythromycin increased the relative abundance of Alphaproteobacteria while decreasing the relative abundances of multiple other classes including Gammaproteobacteria and Sphingobacteriia; and sulfamethoxazole decreased the relative abundance of Betaproteobacteria and increased Alphaproteobacteria. The antibiotic trio had the most wide-ranging effects on the microbiota, increasing the relative abundance of some Sphingobacteriia but primarily decreasing relative abundances across multiple classes.Antibiotic treatment significantly impacted alpha diversity  Differentially abundant taxa in the Daphnia magna microbiota in the 19°C treatment across antibiotic treatments compared to the no-antibiotic control (α < 0.05), as determined by DESeq2 analysis. Bolded values indicate P < 0.05. (C) Post hoc Tukey HSD of cumulative Daphnia magna reproduction across antibiotic treatments and temperature treatments. (D) Post hoc Tukey HSD of first brood size (number of offspring) for Daphnia magna across antibiotic treatments. (E) Post hoc Tukey HSD of Daphnia magna growth across antibiotic treatments and temperature treatments. Download Table S1, XLSX file, 0.03 MB.(A) Pairwise PERMANOVA comparisons of the Copyright © 2021 Cooper et al.2021Cooper et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the Daphnia magna microbiota was significantly impacted by temperature. In the no-antibiotic control, composition was significantly different across temperatures  that was differentially abundant in cold temperatures. In aztreonam, 6 ASVs were reduced in relative abundance in cold temperatures, with a Sphingobacteriia ASV (unidentifiable beyond class) and an Alphaproteobacteria genus experiencing the greatest reductions . In erythromycin, 12 ASVs were differentially abundant across temperatures; of those, the same Sphingobacteriia ASV as in the aztreonam treatment was reduced (2−27.54) in 11°C and a Pseudomonas ASV was more abundant (26.34) in 11°C. Sulfamethoxazole impacted 13 ASVs, including Limnohabitans (2−6.61) and the same Sphingobacteriia ASV (2−25.84). The antibiotic trio treatment had only one differentially abundant ASV . Generally, differentially abundant classes were limited to the Alphaproteobacteria, Betaproteobacteria, Flavobacteriia, and Sphingobacteriia. Sphingobacteriia exhibited the greatest changes in abundance across antibiotic treatments, with a Sphingobacteriia genus experiencing between 2−5 and 2−27.5 reduced abundance in no antibiotics, aztreonam, erythromycin, and sulfamethoxazole at low temperatures as compared to those treatments in the control temperature.The 10.1128/mSystems.00916-20.1FIG S1FIG S1, TIF file, 2.1 MB.Differentially abundant ASVs (α < 0.05) in each antibiotic treatment at 11°C compared to the same antibiotic treatment in the 19°C treatment after 21 days of treatment. Each bar represents a single ASV identified to the genus level, with genus name indicated on the left. Bar color indicates the bacterial class of each ASV, and bar length indicates the fold change in abundance of each ASV. Download Copyright © 2021 Cooper et al.2021Cooper et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the F4,470 = 49.59, P < 0.001). Post hoc Tukey tests revealed that this reduction was most significant in the aztreonam, sulfamethoxazole, and antibiotic trio treatments  , where Daphnia magna treated with sulfamethoxazole experienced a later age at first reproduction than those treated with other antibiotics , hence F4,470 = 19.84, P < 0.001), though no effects of antibiotics on reproduction were observed due to the strong effect of temperature. Daphnia growth was limited in the cold-temperature treatment    . A complsurvival . Host fi< 0.001) . Tempera= 0.013) .10.1128/mSystems.00916-20.2FIG S2Daphnia magna in each antibiotic treatment and temperature treatment. Download FIG S2, TIF file, 1.2 MB.Survival hazard ratios for Copyright © 2021 Cooper et al.2021Cooper et al.https://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International license.This content is distributed under the terms of the Daphnia magna using low doses of targeted antibiotics to examine the impacts of selective suppression on host fitness. We found that aztreonam and sulfamethoxazole, antibiotics targeting abundant bacterial classes in the Daphnia magna microbiome, had the largest impacts on host fitness, primarily in affecting host fecundity. However, our results contrast with those of Sison-Mangus et al. (2015)   and Call. (2015)  in that Daphnia magna microbiome under standard conditions  yields a composition that is similar to that of healthy adult Daphnia magna in other studies, though this genotype has been isolated in laboratory culture for >3 years , but other abundant bacterial classes were similar, including Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria  also delayed age at first reproduction, supporting our hypothesis that suppression of more abundant bacterial classes would have larger impacts on host fitness. Though it is possible that the antibiotics used here have direct effects on host fitness , suggesting that differences in host fitness are mediated through the microbiome. The reduction in host fecundity without a consistent associated decrease in abundance of any particular microbial taxon across treatments suggests that multiple taxa are involved in the functions that benefit host fecundity. It is also possible that the antibiotic treatments reduce host fitness uniquely; for example, the Perlucidibaca ASV (ASV 65) is reduced in aztreonam and in the antibiotic trio but not in sulfamethoxazole, while the Pedobacter ASV (ASV 12) is reduced in all treatments except aztreonam. Although many of the same taxa were suppressed in erythromycin as in both aztreonam and sulfamethoxazole, many more unique ASVs became more abundant. It is possible that the detrimental effects of taxa reduced across all treatments were countered by increases in these ASVs, which include an Ensifer (ASV 18), a Comamonadaceae (ASV 9), and a Sphingopyxis (ASV 7). These ASVs also appear in the antibiotic trio treatment, but a Caulobacter ASV appears as significantly reduced (ASV 66), suggesting that treatment with all three antibiotics simultaneously may counteract the neutral effects observed in the erythromycin-only treatment. Though specific functions encoded by these taxa are unobservable through 16S rRNA sequencing, previous shotgun sequencing work has highlighted some functions in Daphnia-associated species. Specifically, metagenome sequencing indicates that a Pedobacter species uniquely encodes chitin degradation and sialic acid cleavage and that other species (primarily Limnohabitans) may be able to utilize those cleaved sialic acids for amino acid biosynthesis  may indicate that microbe-microbe interactions are affected by targeted antibiotic treatment. Simultaneously, a substantial increase in a Chitinophagaceae ASV (ASV 24) is seen in all treatments except aztreonam; Chitinophagaceae (like Pedobacter) are known chitin degraders and may have detrimental effects on host fitness by utilizing the key material in their host’s carapace. Again, the other ASV changes in erythromycin may counter the potential negative impacts of this taxon on the host, but causality is not understood at this time.Host fecundity was impacted by treatment with aztreonam, sulfamethoxazole, and the antibiotic trio, and host growth was reduced when treated with the trio as well. Sulfamethoxazole  have larger impacts on host fitness than rarer taxa, though previously known important taxa like Limnohabitans are seemingly unperturbed by antibiotics. Within-host microbial communities generally have a skewed abundance pattern, where a few species constitute the majority of total abundance but many species are found in low abundances. Some work indicates that abundant taxa contribute to host fitness  confer greater benefits to host fitness, primarily through functions that contribute to increases in host fecundity and growth, whereas the loss of rare species had little effect on fitness. At the same time, abiotic conditions can have a much larger effect on host fitness than the microbiome, as demonstrated by the changes in Daphnia fitness with temperature not directly mirrored by changes in the microbiota. Our results show that multiple members of the Daphnia magna microbiota impact host fitness in different ways and that these impacts must be understood in the broader context of external factors known to directly affect host fitness. Experiments to disentangle the fecundity-reducing effects of different microbes and the underlying mechanisms in this system are necessary. Continued efforts to isolate members of the Daphnia magna microbiota paired with single-species and community reinfection experiments, metatranscriptome sequencing to identify important microbial transcripts, and metabolic analysis of the microbial cohorts are all potential methods to identify causal factors in these host-microbe and microbe-microbe relationships.Our results suggest that more-abundant classes in the microbiome . C. reinhardtii was cultured in COMBO medium. The volume necessary to provide D. magna with adequate carbon was calculated using the BioTek Epoch microplate spectrophotometer.This experiment was conducted using  Kingdom . Stock cO medium  for multD. magna animals were moved to 35-ml glass vials with COMBO medium and allowed to mature under controlled conditions. Neonates from the third brood of each adult were pooled within 24 h of birth and randomly assigned to experimental treatments . The experimental treatments consisted of five antibiotic treatments crossed with two temperature treatments, 19°C and 11°C. Antibiotic treatments were as follows: a control treatment with no antibiotics, 500 μg/liter aztreonam, 400 μg/liter erythromycin, 250 μg/liter sulfamethoxazole, and an antibiotic trio consisting of all three antibiotics together at the concentrations listed above. These antibiotic concentrations were chosen on the basis of a pilot experiment showing no short-term toxicity effects on D. magna survival but a significant reduction in bacterial abundance . Body size of each D. magna was measured from eyespot to beginning of apical spine before placement into the experimental vials. Experimental D. magna animals were raised in 35-ml glass vials with COMBO for 21 days. Each vial was checked for survival and fed daily with 0.25 mg C/ml/day of the diet treatment. COMBO with the appropriate antibiotic treatment and dose was replenished every 2 days. Vials were also checked daily for offspring, which were counted and removed if present. At the conclusion of day 21 or upon death, D. magna animals were collected from the treatments. Body size was again measured from eyespot to beginning of apical spine to determine growth. D. magna animals from each treatment were pooled in sets of 10 in 1.5-ml microcentrifuge tubes for DNA extraction and processing (n = 4 per treatment).Prior to the experiment, 72 D. magna animals were digested with proteinase K for 24 h to ensure that cells within the carapace were lysed but the carapace was not (GTGCCAGCMGCCGCGGTAA-3′) and 806r (5′-GGACTACHVGGGTWTCTAAT-3′) universal 16S primer pair . Whole  was not . Followimer pair . AmplifiFollowing sequencing, reads were demultiplexed using Illumina’s built-in MiSeq Reporter software. All reads were then analyzed using DADA2  in R. InD. magna life history traits measured as indicators of fitness outcomes included growth, survival, and reproduction. Growth was quantified as the difference between size measurements at the beginning and end of the experiment. Differences in growth among treatments, including the interactions between antibiotics and temperature, were analyzed using an ANOVA. We also used ANOVAs to test for effects of antibiotics and temperature on reproduction, which was measured as number of juveniles per brood and day of first reproductive event . Tukey’s HSD post hoc tests were conducted to determine which treatments significantly differed from the control treatment. Survival rates among treatments were analyzed using the Cox proportional hazards model. Individuals alive at experiment conclusion were coded as censored. We used the threshold cycle (ΔΔTC) method to calculate log fold change in abundance of the 16S rRNA gene among antibiotic treatments, normalizing against the Daphnia magna actin gene  and against the control treatment. A PERMANOVA was conducted among treatments on the calculated unweighted UniFrac distances to test the effects of antibiotics and temperature on microbiota composition, and then pairwise comparisons of antibiotic treatments in each temperature were conducted to find treatments with significantly different overall community composition. DESeq2 was used to find differentially abundant taxa among treatments.All statistical tests were performed in R. Host PRJNA543842 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA543842) under accession numbers SRX5866173 to SRX5866265. All code, life history data, and a .rds containing the DADA2-processed read data used in this study are available at https://github.com/reillyowencooper/ab-targeting-daphnia.Raw read data are available in the Sequence Read Archive in BioProject


Improvements in tensile strength and impact resistance of concrete are among the most researched issues in the construction industry. The present study aims to improve the properties of concrete against impact loadings. For this purpose, energy-absorbing materials are used along with fibers that help in controlling the crack opening. A polymer-based energy-absorbing admixture, SBR latex, along with polypropylene fibers are used in this study to improve the impact resistance. Along with fibers and polymers, the effect of the size of aggregates was also investigated. In total, 12 mixes were prepared and tested against the drop weight test and the Charpy impact test. Other than this, mechanical characterization was also carried out for all the 12 concrete mixes. Three dosages of SBR latex, i.e., 0%, 4%, and 8% by weight of cement, were used along with three aggregates sizes, 19 mm down, 10 mm down, and 4.75 mm down. The quantity of polypropylene fibers was kept equal to 0.5% in all mixes. In addition to these, three control samples were also prepared for comparison. The mix design was performed to achieve a normal-strength concrete. For this purpose, a concrete mix of 1:1.5:3 was used with a water to a cement ratio of 0.4 to achieve a normal-strength concrete. The experimental study concluded that the addition of SBR latex improves the impact resistance of concrete. Furthermore, an increase in impact resistance was also observed for a larger aggregate size. The use of fibers and SBR latex is encouraged due to their positive results and the fact that they provide an economical solution for catering to impact strains. The study concludes that 4% SBR latex and 0.5% fibers with a larger aggregate size improve the resistance against impact loads. Concrete is widely used in various civilian and military buildings in Pakistan and is one of the most important construction materials used all over the world. The main concern related to concrete is its low tensile strength and weak resistance against cracking, which makes it brittle. Terrorism is the biggest problem of many countries on the globe these days. Among these countries, Pakistan has witnessed many major terrorism attacks on important public and private sector buildings in the recent past, which inflicted many deaths and left hundreds with wounds. It has been observed that the major cause of loss of life was the severe damage of structural elements during terrorist attacks resulting in the failure of the building. Furthermore, investigations have highlighted that the conventional concrete used in those structures subjected to blast loadings was not resistant enough to bear such high strain loadings ,2.Among different important mechanical properties of concrete, impact resistance is the one which needs to be carefully studied to make the reinforced concrete (RC) structure blast-resistant. In this regard, researchers are carrying out extensive research on the improvement in the impact resistance of normal-strength concrete. To improve the impact resistance of concrete, various advanced materials, such as man-made and natural fibers, have been extensively studied in various experiments ,4,5. TheXu et al.  studied Wang et al.  revealed3, which comes out to be around 4% of the cement weight. The results obtained in the research also concluded that the addition of SBR latex has no significant effect on cement hydration in the long term. Besides, continuous SBR latex films formation presented in cement substrates makes it possible to raise toughness and compact degree of the interface transition zone (ITZ). Furthermore, SBR latex triggers fiber and cement paste, which then leads to a tight mutual connection.Another similar study  concludeAlong with polymers, various types of fibers have also been studied to improve the impact resistance of ordinary concrete. Fibers are mainly categorized into two types, namely flexible fibers and stiff fibers. Polypropylene and carpet nylon are some typical examples of flexible fibers, while steel fibers, basalt fibers, and carbon fibers are classified as stiff fibers.Fu et al.  studied Besides the addition of fibers and polymers, many researchers have also investigated the effect of aggregate size on the impact resistance of concrete. Most studies concluded that for a normal-strength concrete, both strength and fracture energy increase with the increase in coarse aggregate size ,15,16. HACI 544  specifieThe literature review revealed that the addition of fibers and the use of polymers in concrete is an effective approach to enhance its impact resistance. In most previous research studies, the combined effect of fibers and polymer has been studied on the impact resistance of concrete. Many studies have also investigated the effect of aggregate size variation on the fracture energy and compressive strength of concrete. However, the influence of aggregate size along with fibers and polymers on the impact resistance of concrete is rarely investigated. Thus, the present study is focused to explore the combined effect of polypropylene fiber and SBR latex along with the variation of aggregates size. Further, the suitability of a non-ACI test specimen, i.e., U-shapes, was also investigated.3, was used in all concrete mixes. Locally available river sand (Lawrencepur) and crush stone (Sarghodha) were used as fine and coarse aggregates, respectively. For coarse aggregates, three different maximum aggregate sizes, i.e., 4.75 mm, 10 mm, and 19 mm, were used. Properties of fine and coarse aggregates are given in Ordinary Portland cement (OPC) of type-1, complying with ASTM C-150  and haviPolymer admixture, known as SBR latex (styrene–butadiene rubber), is usually considered as a binding agent. Further, the formation of polymer structure within the concrete matrix also imparts a positive effect on the impact resistance of concrete . DiffereIt is a well-established fact that fibers of different types improve the mechanical properties  of plain concrete, particularly in post-crack regions . In thisA total of 12 concrete mixes, using (were prepared) 3 different coarse aggregate sizes and 2 distinct SBR latex at dosages, were prepared. In all mixes, polypropylene fibers were included at constant dosage (0.5%), except the control mixes. Among twelve concrete mixes, three were control mixes, which were prepared without the use of SBR latex and fibers, and three mixes contained only polypropylene fibers. The remaining six concrete mixes were prepared using both polypropylene fibers and SBR latex with specific aggregate sizes. Each concrete mix is referred to with a proper designation as mentioned in (1)ϕ × 300 mm were used for determining mechanical properties, which include compressive strength, MOE, and split cylinder tensile strength.Concrete cylinders of standard size of 150(2)ϕ × 300 mmwere usedfor preparing disc specimens for the Charpy impact test.Concrete cylinders of size of 40(3)The concrete specimens for the drop weight impact test are as follows:The following concrete specimens were cast to determine the mechanical properties and impact resistance of concrete mixes. Details of the specimen are provided in ϕ × 200 mm were used for preparing cylindrical discs of 63.5 mm height for drop weight test, as specified by ACI 544 [Concrete cylinders with a size of 100 ACI 544 ;U-shape specimens, according to the dimensions suggested by Zhu et al. , as showRequired quantities of all ingredients for a particular concrete mix were first used to dry mixes, along with the addition of fibers through manual sprinkling. This dry mixing process was continued until a uniform mix was achieved. The average time for this process was observed to be 4 to 5 min for each concrete mix. After the addition of water along with a required quantity of SBR latex, the wet mixing was continued for another three minutes. Before pouring concrete into molds for slump test, all steel molds were oiled before pouring concrete. The compaction of concrete was carried out through the vibrating table. The specimens were demolded after 24 h of casting, and then concrete specimens were placed in the curing room for 28 days. The compression and modulus of elasticity tests were performed on the cylindrical samples after 28 days. The test specimens used for drop weight were prepared by cutting the cylinders (100 mm in diameter × 200 mm in length) to obtain the disc height of 63.5 mm from the central region of the concrete cylinder. This method of obtaining cylindrical disc specimens is based on the ACI 544 . Figure For the mechanical characterization of SBR-latex-modified fiber-reinforced concrete, various tests were performed in the laboratory.For mechanical characterization, all the testing was conducted in a fully calibrated universal testing machine, following a proper ASTM procedure, i.e., ASTM C39 , ASTM C4In this study, two types of impact tests were performed. Impact resistance tests were conducted in accordance with ACI 544.2R-89 .(a)Drop weight impact testThe arrangement for the drop weight impact test was prepared in the lab, as shown in N1 = the drop weight potential energy at initial cracking;N2 = the drop weight potential energy at final failure;B1 = the number of blows at initial cracking;B2 = the number of blows at final failure.In the case of the impact load test on the U-shape specimen, a 2.5 kg (5.5 lbs) hammer was used with a drop height of 128 mm. In this test, the U-shape specimen was fixed at the bottom of the testing setup at the required position with respect to the line of action of load, as shown in (b)The Charpy impact testM = the mass of fork = 22.9 kg;R = the radius of fork = 700 mm;θ1 = the free-fall angle;θ2 = the post-impact angle.During the Charpy impact test, a flexural impact loading was induced by a pendulum fork, as shown in The results of compressive strength values for all 12 concrete mixes are arranged in three groups with reference to the size of the maximum aggregate used in the study, as shown in A similar trend of compressive strengths values was found in all of these three groups. When fiber was added to concrete, the strength of the fibrous mixes was slightly dropped, and this observation is in line with the previous research studies on fiber-reinforced concrete. The reason for this drop in compressive strength is the reduced density of concrete mix due to the addition of fibers. It is evident from the results that when 4% SBR latex was added, the compressive strength of the resulting concrete mix slightly improved. The maximum improvement of 15% was observed for the case of the F-4S group (0.5% fibers and 4% SBR latex) as capered to the control mix. This was true for both concrete mixes made using the aggregate with maximum sizes of 10 mm and 19 mm. The improvement in compressive strength due to the addition of SBR latex is mainly due to the formation of polymer structure, which results in an enhancement of concrete density. However, when 8% SBR latex was added, the compressive strength of the resulting concrete mix reduced, far less than that of the compressive strength of the control mix. The maximum drop of 18% (33 MPa to 27 MPa) was exhibited by concrete mix made using the maximum aggregate size of 19 mm  when compared to the corresponding control mix. A change in the hydration kinetics due to excessive quantity of SBR latex or internal cracking of concrete matrix, as a result of excessive formation of polymer structures, could explain the detrimental effects of 8% SBR latex on compressive strength. Therefore, it is recommended that the microstructure of such concrete mixes must be studied to highlight the reason for the drop in compressive strength.Further, the elastic modulus of all concrete mixes was also computed experimentally, and results are shown in For each concrete mix, two specimens were tested, and average results are presented in On the contrary, the addition of 8% SBR latex showed a negative effect on the indirect tensile strength similar to that of compressive strength. The maximum drop of 27% was exhibited by a concrete mix made using the maximum aggregate size of 19 mm, 0.5% fibers, and 8% SBR latex (19-F-8S) when compared to the corresponding control mix. The drop in the indirect tensile strength of fibrous concrete mix in the case of 8% SBR latex is attributed to the excessive formation of polymerization structure due to the overdosage of SBR latex.The Charpy impact tests were performed according to the ASTM standard A370 . Three smax-19) showed smaller energy absorption values as compared to the concrete mixes with maximum aggregate sizes of 4.75 mm and 10 mm. The reasons for this smaller energy absorption impact for concrete mixes with Dmax-19 may be linked to the ratio of the size of a specimen prepared for this test and the maximum particle size of aggregate used.The results revealed that all concrete mixes with a maximum aggregate size of 19 mm  was exhibited by (19 + F + 8S) when compared to the corresponding control mix.max-19), the fracture concentered around the aggregates.In addition, due to larger aggregate sizes, the hammer could directly stroke over the aggregate particles and energy did not distribute to the adjoining aggregates. This quite evident from the failure mode obtained from the Charpy impact test, as shown in Drop weight tests were performed according to ACI 544 . Three sWhen fibers were added to concrete, the impact resistance increased because the polypropylene fibers delayed the crack propagation. A significant increase in the impact resistance of concrete can be seen when 4% SBR latex was added. On the contrary, when 8% SBR latex was added to concrete, the impact resistance was decreased. This reduction in impact resistance of concrete may be due to excess formation of the C-S-H structure, which made the concrete brittle. Concrete mixes with 0.5% fibers and 4% SBR latex F-4S a attaineAnother trend observed in drop weight testing was the increase in impact resistance with the increase in aggregate size. This trend can be observed in all the concrete groups; control mix, i.e., Cont., F, F-4S, and F-8S . The maximum improvement of 57% (204 J to 321 J in N2) was achieved by the control concrete mix when the aggregate size increased from 4.75 mm to 10 mm. Furthermore, the same increase in impact resistance energy was observed in concrete mixes F, F-4S, and F-8S, when the aggregate size increased from 4.75 mm to 10 mm. However, when the maximum aggregate size increased from 10 mm to 19 mm, the increase in impact energy was only about 7% to 8%, due to the smaller fiber size as compared to aggregatesTwo distinct types of failure pattern of disc sample, namely Y-shape and center split failure, as shown in The tests on U-shape concrete specimens were also performed according to ACI 544  and guidFrom the results presented in (1)The addition of polypropylene fibers has an insignificant effect on mechanical strength. However, with the addition of 4% SBR latex, strength values (compressive and tensile) increased. Further, the addition of 8% SBR latex had a negative impact on the mechanical properties of the polypropylene fiber-reinforced concrete.(2)The impact resistance of polypropylene fiber-reinforced concrete determined through the drop weight test on disc specimen was enhanced by the addition of 4% SBR latex. This enhancement was 1.7 to 2.9 times up to the initial crack, while it was 1.05 to 1.30 times the value of the control concrete mix at final failure.(3)For the concrete containing 4% SBR latex, after the initial cracking of disc specimen under impact loading, the presence of polypropylene fibers caused a 32% increase in energy absorption capacity up to final failure which was 55% in the case of the control mix.(4)With the increase in maximum aggregate size from 4.75 mm to 19 mm, the compressive strength and impact resistance of concrete (obtained through drop weight test on disc specimen) increased by 20% and 75%, respectively.Based upon the experimental results the following conclusions can be drawn.(5)Experimental observations showed that the Charpy test is not reliable for large-size aggregate concrete with respect to the sample size used in this study.The results obtained for impact resistance of concrete through the drop weight test on the disc specimen and the U-shape specimen cannot be compared, as the mode of failure is different in both cases. There is compression in the case of the disc specimen and flexure in the case of the U-shape specimen. Furthermore, in a U-shape sample, the impact force is more localized as compared to the regular disc.


N-methylisoquinolinium trifluoromethanesulfonate(Kass of 500 ± 30 M–1 in CD2Cl2) can be dissipatively driven bymeans of 2-cyano-2-(4′-chloro)phenylpropanoic acid used asa convenient chemical fuel. When the fuel is added to a dichloromethanesolution containing the above complex, the host is induced to immediatelyrelease the guest in the bulk solution. Consumption of the fuel allowsthe guest to be re-uptaken by the host. The operation can be satisfactorilyreiterated with four subsequent additions of fuel, producing foursuccessive release–reuptake cycles. The percentage of the guesttemporarily released in the bulk solution by the host and the timerequired for the reuptake process can be finely regulated by varyingthe quantities of added fuel.The host–guestinteraction of a 1,3,5-trisaminocalix[6]arenereceptor with  The twosinglets at 3.0 and 3.6 ppm correspond to the methoxy groups, whilethe singlet at 3.8 ppm is due to the 12 protons of the methylene bridges.Singlets at 6.0 ppm and 7.2 ppm are due to the aromatic protons ofrings a and b, respectively.A significantportion of the 3 is conformationallyflexible,15 due to a fast rotation of thearomatic rings around the methylene hinges on the NMR time-scale.With the aim at testing N-methylisoquinolinium trifluoromethanesulfonate 4 as a suitable guest for calix[6]arene 3, thelatter was titrated with 4 in CD2Cl2 by 1H NMR. The resulting spectra are reported in 3.The aromatic singlets of moieties a and b diverge on increasing concentrations of 4. In the meantime,the methoxy signals are down-field shifted, and the singlet relatedto the methylene bridges becomes broader and broader, due to a rigidificationof the structure when guest 4 is hosted inside 3. This loss of conformational flexibility is confirmed bythe low-temperature spectra of 3 in presence of a 50-foldmolar excess of 4, with the appearance, at −10°C, of two doublets for the methylene protons , typical of a blocked cone conformationof the calixarene.16 At the same temperature,in the absence of the guest, the methylene protons give a single,slightly broadened signal . The fit of the experimental points obtained in the titration of 3 with 4 with a 1:1 binding isotherm gives abinding constant Kass of 500 ± 30M–1 with a very nice accordance between the calculatedcurve and the experimental data .The presence of a single singlet for the protons of the methylenicbridges indicates that calix[6]arene 3 with 4, a significant shift of the signals of the guest 4 is also observed. In the first point of the titration (see b), when added titrant 4 is equimolar to calix[6]arenehost 3, the percentage of added 4 complexedto 3 is significant (38%). Inclusion of guest 4 into the aromatic cavity of host 3 is proved by themarked shielding effect observed on the signals of the guest uponcomplexation. Under the above conditions, a 0.68 ppm up-field shiftis observed on the signal of the methyl group of the guest . Among the aromatic signals related to 4, that of the alpha proton (Hα) is the most up-field shifted (it is found at 9.30 ppm in trace b of 4 as a sharper singlet) indicating that the inclusion must occur asdepicted in Interestingly, along the titration of 3 by titration with trifluoroacetic acid (TFA). Addition ofthe firstmolar equiv of TFA to a 2.00 mM solution of 3 causesa general down-field shift of all signals due to the protonation ofone of the three amino groups . Further significant variations are observed when a second anda third molar equiv of TFA are added to the solution. In the lattercase, most of the signals related to 3 appear broader,and some of them begin to show multiplicity as a consequence of anincreased conformational rigidity. 1H NMR spectra  do not seem to change appreciablyupon subsequent additions of TFA (up to 12 molar equiv). A definiteassessment of the protonation state of 3 after the additionof 3 or more molar equiv of TFA is not easy. Doubly protonated 3H22+ with one of the two protons onone of the three amino groups and the other shared between the remainingtwo amino groups (see 3H33+) with one proton on each of the aminogroups, could be formed. However, the doubly protonated state 3H22+ seems to be more probable takinginto account the following arguments. First, in strict analogy towhat was observed in the case of the monoprotonated form of calix[4]arene 2H+ , proving that 3 has a much more basic character than p-anisidineprobably due to the chance given to two amino groups to share theproton17 . An additional clue in favor of the 3H22+ hypothesis in the presence of 3 or moremolar equiv of TFA, comes from the pattern of the methylene bridgesignals of the 1H NMR spectrum obtained under these conditions. They appear as two broaddoublets, a typical feature of an almost blocked or slowly interconvertingcone conformation. Such conformation is hardly ascribable to a triprotonated 3H33+ structure, which would adjustto keep the three positive groups as far as possible but is fullycompatible with the 3H22+ formin which the two protons can be rapidly scrambled among the threeamino groups.Next, we tested the basic properties of calix[6]arene oups see S6. Furthoups see S6. Furthoups see S6. Furth3 toward N-methylisoquinolinium triflate 4.a is the 1H NMRspectrum of aCD2Cl2 solution of 2.00 mM 3 and6.00 mM 4. Under these conditions, 70% 3 is in the form of 3•4 complex.The addition of 3 molar equiv of TFA causes the complete expulsionof guest 4 from host 3 as can be seen inthe resulting trace b of b is indeed thesum of the 1H NMR spectrum of 4, trace c, and that of 3 + 3 molar equiv of TFA, trace d. The reason is probably electrostatic in nature: oncehost 3 is protonated, it loses any affinity for the positivelycharged N-methylisoquinolinium.Trace 3 isable to promote the decarboxylation of the fuel acids. As expected,it was found that the decarboxylation of acid 1d (themost activated among 2-cyano-2-phenylpropanoic acids) promoted by 3 occurs in relatively quick times (the reaction is completewithin 6.2 h in CD2Cl2 at 25 °C).18 To an initial 2.00 mM 3 solution is added and 3 is immediately protonated .Firstof all, we investigated if calix[6]arene trace a, 6a, fuel trace b, 6a. Decar3 returnsto its originalnonprotonated form. Interestingly, the reaction does not occur toany extent within the same time when p-anisidine(6.00 mM) is added instead of 3, strongly pointing tothe sharing of the proton between two of the three amino groups in 3H+ as a reason for the increased basicity of 3. The same experiment was then repeated in the presence of2.00 mM 4.Contextually, calix[6]arene 3 is engaged in the formationof complex 3•4 , host 3 is immediately protonated, and guest 4 is released into the bulk solution  appears among the reaction products. Peroxide 5 in SI, pages S14–S15). It does not form inthe absence of 4 (4 butsubstituting 3 with Et3N (a base able to promotethe decarboxylation of 1d). In other words, it is onlyformed when calix[6]arene 3 and N-methylmethylisoquinoliumtriflate are both present in the reaction mixture. We hypothesizethat it is due to the oxidation of the carbanion by 4,20 immediately followed by oxygen capture,see N-methylisoquinoline radical must be then re-oxidized to N-methylisoquinolinium (very likely by O2) sincethe latter is found untouched at the end of each cycle.Under these conditions, 38% trace a, 6b. Now,trace b, 6b. Decarnditions6c.19 Theperiment6b, a secnce of 4 6a. Furth3,21 does notinterfere on the release–reuptake cycles. Interestingly, thecontribution of the collateral pathway definitely decreases (passingfrom 25 to 15%) when the exclusion of O2 from the solutionwas attempted through freeze–pump–thaw cycles operatedon the NMR tube or when higher excesses of fuel 1d, 10.5mM (5.25 mol equiv) and 18.4 mM (9.2 mol equiv) were added , vide infra.Thus, this collateral pathway, which is somewhat facilitated bycalix[6]arene 1d added in the solution. 1d were added to mixtures of 3 (2.0mM) and 4 (2.0 mM). The percentage of 4 temporarilyescaped from 3 and the time spent outside increase onincreasing the amount of the fuel added. When 3 molar equiv of 1d are added  after the exhaustion of excess fuel is probably dueto an autocatalytic path involving deprotonated 3 itselfas the catalyst. Such complex mechanism has been studied in detailin the simpler case of calix[4]arene 2.9c In that case, it was shown that the fact that the rateof the autocatalytic process does not slow down on decreasing thesubstrate (fuel) concentration, with the consequent presence of acusp just before the final plateau, can be explained considering theautocatalytic path to be kinetically zero order with respect to thesubstrate itself.22 The presence of minute amountsof cationic impurities in dichloromethane was shown to be likely responsiblefor such bizarre kinetic behavior.9cEventually, time control of the dissipative release–reuptakecycle could be achieved by varying the amount of fuel 3 and N-methylisoquinoliniumtriflate 4 can be dissipatively driven by fuel acid 1d. The addition of the fuel into a solution containing thecomplex 3•4 causes the temporaryrelease of guest 4 by the host into the bulk. The formeris re-uptaken by the latter once the fuel is exhausted. The amountof released guest and the duration of the unloaded state can be controlledat will by a fine modulation of the quantity of added fuel. Thus,the fully abiotic host–guest couple (3•4) described above is capable of operating under dissipativeconditions , whichare typical, operative conditions of systems with life-like properties.In this report, we have shown that the host–guestinteractionbetween calix[6]arene 23A possible development of the present work could be the designof systems where the dissipative complex dissociation gives rise toa secondary effect. The temporal control of catalytic activity maybe, for example, obtained in case the guest is a catalyst of a givenreaction.


The five-year survival for resectable proximal gastric, gastroesophageal junction (GEJ), and distal esophageal cancer ranges from 30 to 60% globally. Neoadjuvant and/or perioperative therapy has emerged as a treatment tool to improve patient selection for surgery, resectability, and locoregional control of the disease. As a result, treatment strategies have evolved from the first trials in the late 1980s to the pivotal CROSS trial updated in 2015. The review summarizes current clinical trials and treatment recommendations with regard to neoadjuvant and/or perioperative therapy for patients with adenocarcinoma and squamous cell carcinoma of the distal esophagus, GEJ, and proximal stomach.Neoadjuvant treatment strategies for resectable proximal gastric, gastroesophageal junction (GEJ), and distal esophageal cancer have evolved over several decades. Treatment recommendations differ based on histologic type—squamous cell carcinoma (SCC) versus adenocarcinoma (AC)—as well as the exact location of the tumor. Recent and older clinical trials in this area were critically reviewed. Neoadjuvant chemoradiation with concurrent taxane- or fluoropyrimidine-based chemotherapy has an established role for both AC and SCC of the distal esophagus and GEJ. The use of perioperative chemotherapy for gastric AC is based on the FLOT4 and MAGIC trials; however, the utility of neoadjuvant chemoradiation in this setting requires further evaluation. Additional clinical trials evaluating chemotherapy, targeted therapy, immunotherapy, and radiation that are currently in process are highlighted, given the need for further disease control. Gastroesophageal junction (GEJ) cancer has historically been composed of distinct anatomic locations, including proximal gastric, true GEJ, and distal esophagus, based on the Siewert classification system ,2. GlobaIn the United States (US), the rate of esophageal cancer is 5.7 per 100,000, with up to 50% presenting with localized or regional disease ,4. ProjeGastric cancer incidence varies geographically, with rates ranging from 3.0 to 32.2 per 100,000 depending on country and gender . The fivAccording to the National Comprehensive Cancer Network (NCCN) Guidelines, distal esophagus and GEJ cancers are managed distinctly from proximal gastric cancer . These aNCCN guidelines recommend endoscopic resection or surgery for Tis-T1b gastric cancer . ResectaThis review is focused on neoadjuvant therapies for resectable disease and will highlight the most important clinical trials and meta-analyses.Six randomized controlled trials (RCTs) evaluated the role of neoadjuvant chemotherapy followed by surgery vs. surgery alone for esophageal SCC ,20,21,22n = 46) and Maipang (n = 46) conducted RCTs which found no benefit to neoadjuvant chemotherapy vs. surgery alone [p = 0.003) [n = 42) evaluating the use of Cisplatin + 5-Fluorouracil (5-FU) + Leucovorin [n = 94) et al. evaluated the use of cisplatin + 5-FU and found significant differences in 5-year survival rate when comparing responders vs. non-responders  [n = 169) et al. evaluated the use cisplatin + etoposide with significant improvement in survival vs. surgery alone  [n = 247) patients with cisplatin + 5-FU with significant differences in OS across the entire study, although the SCC subgroup failed to reach significance  [n = 207) with the same regimen and found no significant difference in overall survival, though multivariate analysis showed a survival advantage in patients who had a response to chemotherapy, <10% weight loss, and AC histology [In 1988, Roth et al. compared 39 patients treated either with upfront surgery or with perioperative chemotherapy (Cisplatin + Vindesine + Bleomycin) followed by resection. There were significant differences in median overall survival (mOS) when comparing responders vs. non-responders vs. upfront surgery (20 vs. 6.2 vs. 8.6 months) . Howeverry alone ,18. Law  0.0002) . Boonstr = 0.03) . The OEO61–1.07) . Most reIn summary, multiple RCTs report differences in OS based on pathologic response to chemotherapy ,19,21,24Three RCTs compared chemoradiation vs. surgery alone for patients with esophageal SCC ,26,27. Fn = 217) evaluated the independent effects of chemotherapy and radiation (35 Gy) prior to surgical resection. They found no benefit of chemotherapy, while radiation improved OS either with (p = 0.05) or without chemotherapy (p = 0.01) [n = 282) treated patients with cisplatin + 37 Gy and found no differences in survival compared to surgery [n = 101) treated patients with cisplatin + 5-FU + 45.6 Gy with no benefit in OS compared to surgery alone [n = 128) evaluated a mixed group treated with cisplatin + 5-FU + 35 Gy with no significant difference in OS, though there was a higher rate of R0 resection in the chemoradiation group  [n = 194) evaluated cisplatin + 5-FU + 45 Gy with no benefit observed in the treatment group [n = 50) treated with cisplatin + 5-FU with and without 40 Gy radiation and found no survival benefit with the addition of radiation [p = 0.049) [p = 0.003) [p = 0.008).In 1992, Nygaard et al. ( = 0.01) . There w = 0.01) . Similar surgery . Furtherry alone . Urba etry alone . Burmesi= 0.002) . FFCD 99nt group . NeoRes adiation . However= 0.049) . Collect= 0.049) . The sur= 0.003) . The SCCSuccinctly, although neoadjuvant chemoradiation did not seem to offer a survival benefit when compared to surgery alone in several trials, the CROSS trial was able to establish the benefit of neoadjuvant chemoradiation for esophageal SCC ,29,30,31One RCT evaluated induction chemotherapy prior to chemoradiation in SCC . Anothern = 97, includes 2 AC patients) evaluated induction chemotherapy  followed by 47 Gy of chemoradiation vs. chemoradiation alone (47 Gy) with no significant difference in overall survival [n = 87) the use of intratumoral injection of paclitaxel in conjunction with chemoradiation (cisplatin + 5-FU + 50.4 Gy) compared to chemoradiation alone and found improved pathologic response in the group with chemoradiation alone  [Yoon et al.  .Based on these studies, there does not appear to be added benefit of induction chemotherapy or intratumoral injection of paclitaxel in addition to neoadjuvant chemoradiation for esophageal SCC.One RCT evaluated neoadjuvant chemotherapy vs. surgery in patients with AC of the esophagus or GEJ . Two RCTn = 224) evaluated perioperative chemotherapy (cisplatin + 5-FU) vs. surgery with improvement in OS  [n = 533) and SCC patients with cisplatin + 5-FU and found a statistically significant overall survival benefit across the entire study population . However, in a subset analysis of the AC subgroup, this difference did not achieve statistical significance  [n = 123) and SCC with the same regimen (cisplatin + 5-FU) with no significant difference seen in OS [Ychou et al. ( = 0.02) . OEO2 ev.05, NS) . RTOG 89In summary, based on the available information specific to distal esophageal or GEJ adenocarcinoma, neoadjuvant cisplatin + 5-FU chemotherapy has demonstrated a survival benefit over surgery alone in some studies, but not others. The combination of fluoropyrimidine- and platinum-based chemotherapy may be beneficial for patients who cannot tolerate triplet chemotherapy regimens or chemoradiation.Five RCTs have compared different perioperative and neoadjuvant chemotherapy regimens for distal esophageal and GEJ AC ,38,39,40n = 43) evaluated perioperative chemotherapy with 5-FU + Leucovorin + Oxaliplatin +/− Docetaxel (FLO vs. FLOT)) and found a nonsignificant trend towards improved progression free survival (PFS) with the triplet FLOT regimen [n = 1063) evaluated perioperative chemotherapy (Epirubicin + Cisplatin + Capecitabine +/− Bevacizumab) and found no significant survival benefit and an increased risk of anastomotic leak with bevacizumab [n = 897) evaluated neoadjuvant chemotherapy (Cisplatin + 5-FU vs. Epirubicin + Cisplatin + Capecitabine) with no significant differences in OS [n = 716) demonstrated a survival advantage of perioperative 5-FU + Leucovorin + Oxaliplatin + Docetaxel (FLOT) compared with Epirubicin + Cisplatin + 5-FU/Capecitabine (ECF/ECX) with 56% of patients with distal esophageal/GEJ adenocarcinoma  [n = 1022) evaluated perioperative  vs. adjuvant  with a benefit in the perioperative treatment group for disease free survival  [FLOT65+ ( regimen . MRC ST0acizumab . MRC OEOes in OS . FLOT4 (= 0.012) . The RES= 0.027) .Summarizing the above, perioperative chemotherapy regimens have shown a survival benefit in distal esophageal and GEJ AC. Bevacizumab does not appear to improve survival and may increase complications related to wound healing. FLOT  improves OS compared to ECF (Epirubicin + Cisplatin + 5-FU/Capecitabine). The FLOT regimen has emerged as the standard of care currently for patients fit enough to receive it. Of note, up to 50% of these studies pooled patients with both distal esophageal/GEJ AC and proximal gastric AC, limiting our ability to draw conclusions on each subgroup.Two RCTs have evaluated neoadjuvant chemoradiation compared to surgery ,42. Fourp < 0.05) [n = 132) evaluated neoadjuvant chemoradiation  vs. surgery and found an improvement in 3-year OS  [n = 275) treated with Carboplatin + Paclitaxel + 41.4 Gy. Though the greatest benefit of chemoradiation was seen in the SCC subgroup, patients with AC also had significantly improved survival  [Several trials have evaluated the benefit of neoadjuvant chemoradiation. Zhao et al. showed in a Phase II study of 76 patients that neoadjuvant chemoradiation with Oxaliplatin + Capecitabine + 45 Gy was associated with an increased rate of R0 resection versus surgery alone  . However= 0.019) . Similar= 0.019) . However= 0.019) . In addi= 0.019) . AlthougIn summary, three trials have shown that neoadjuvant chemoradiation improves survival in patients with distal esophageal and GEJ AC ,32,42. CSeven RCTs evaluated neoadjuvant chemoradiation compared to induction chemotherapy and chemoradiation ,46,47,48n = 76, 47.2% vs. 27.7%, p = 0.07) [n = 126) evaluated neoadjuvant chemoradiation with induction chemotherapy  vs. neoadjuvant chemoradiation alone and found no significant change in OS [n = 65, including 4 SCC) evaluated neoadjuvant chemoradiation with induction chemotherapy (5-FU + Leucovorin + Cisplatin & Etoposide + Cisplatin + 30 Gy) vs. chemotherapy alone (5-FU + Leucovorin + Cisplatin), with a significant improvement in PFS , and an improvement in OS that approached statistical significane  [n = 75) et al. evaluated neoadjuvant chemoradiation (Cisplatin + 5-FU + 35 Gy) vs. chemotherapy (Cisplatin + 5-FU) with improvement in pathologic response but no significant differences in PFS or OS [n = 131) treated with cisplatin + 5-FU +/− 40 Gy and reported no significant difference in survival [n = 66) evaluated neoadjuvant chemotherapy (Cisplatin + 5-FU + Docetaxel) with or without chemoradiation (45 Gy) after non-response to initial regimen documented by Positron Emission Tomography (PET). DCF + radiation vs. DCF alone resulted in a non-significant difference in 5-year OS to 46% vs. 31% [n = 85) evaluated two neoadjuvant chemoradiation regimens  with improved OS in the latter treatment group  [Several trials have evaluated the benefit of induction chemotherapy. Stahl et al. evaluated neoadjuvant chemoradiation with induction chemotherapy (5-FU + Leucovorin + Cisplatin + 30 Gy) vs. chemotherapy with no significant difference in 3-year survival possibly due to sample size ( = 0.07) . Ajani ege in OS . The POE= 0.055) . Other tFS or OS . Similarsurvival . Combini= 0.035) .In summary, the first two trials approached significance demonstrating the benefit in adding neoadjuvant chemoradiation after induction chemotherapy compared to the same induction chemotherapy regimen ,46. TherThree RCTs evaluated neoadjuvant or perioperative chemotherapy vs. surgery alone in gastric AC ,50,51. On = 372) and received perioperative chemotherapy  vs. surgery alone with improved overall survival  [p = 0.02) [n = 60) evaluated neoadjuvant capecitabine vs. surgery with no significant change in 5-year OS , likely because the study was underpowered to show an effect of single-agent therapy [n = 144) evaluated neoadjuvant chemotherapy (Cisplatin + Leucovorin + 5-FU) vs. surgery and failed to show significant survival benefit , although more patients had R0 resection in the neoadjuvant group  [Two trials evaluated the use of perioperative chemotherapy. The MAGIC  trial established chemotherapy as the standard of care for patients with resectable gastric AC . Overall= 0.009) . The Fre = 0.02) . Two oth therapy . Lastly,= 0.036) .Based on the above, trials with perioperative (rather than neoadjuvant only) chemotherapy appeared to show more benefit with the caveat that the FFCD trial included a minority of gastric AC patients. Perioperative chemotherapy may be offered in patients with resectable gastric AC greater than the cT1N0 stage based on the results of the MAGIC trial.Three trials compared different neoadjuvant chemotherapy regimens prior to surgery ,37,40 fon = 21 gastric AC of a total of 43 patients) evaluated perioperative chemotherapy  with a no significant differences identified [n = 716) evaluated perioperative chemotherapy with 5-FU + Leucovorin + Oxaliplatin + Docetaxel (FLOT) vs. Epirubicin + Cisplatin + 5-FU/Capecitabine (ECF) with improved OS in the FLOT group  [n = 383 of 1063 gastric AC) evaluated perioperative chemotherapy with Epirubicin + Cisplatin + Capecitabine +/− Bevacizumab with no significant differences in OS. However, there was an additional risk of anastomotic leak with bevacizumab [n = 649 gastric AC of a total of 1022 patients) evaluated perioperative  vs. adjuvant  with a benefit in the perioperative treatment group .All of the following trials evaluated perioperative chemotherapy in various regimens. FLOT65+ (entified . FLOT4 (= 0.012) . Howeveracizumab . The RESTaken together, these data indicate that FLOT is the perioperative regimen of choice for younger patients with gastric AC and that perioperative chemotherapy offers survival benefits compared to adjuvant chemotherapy alone.One RCT evaluated chemoradiation in patients with gastric AC . One trin = 653 gastric AC of a total of 788 patients) evaluated neoadjuvant chemotherapy with adjuvant chemoradiation  vs. perioperative chemotherapy, with no significant improvement in OS [n = 18 of 94 with gastric resection) neoadjuvant chemoradiation with induction chemotherapy (5-FU + Cisplatin + Leucovorin + 30 Gy) vs. neoadjuvant chemotherapy with no difference in 3-year survival  [CRITICS (nt in OS . Stahl e = 0.07) . HoweverBased on the above, the role of neoadjuvant chemoradiation is unclear for patients with gastric AC.p < 0.0001) [p = 0.007) [p = 0.01) [n = 866) only evaluating clinical trials found a benefit in OS when comparing neoadjuvant chemoradiation to chemotherapy  [n = 709) evaluating neoadjuvant chemoradiation vs. chemotherapy for SCC and AC showed a benefit for OS in SCC , but not AC patients [The value of neoadjuvant chemotherapy vs. surgery alone was assessed by Faron et al. in meta-analysis with significant benefit in OS favoring neoadjuvant chemotherapy  . There a 0.0001) . Kumar e= 0.007) . Neoadju = 0.01) . However = 0.03) . Last, apatients .n = 1056) showed a significantly higher rate of negative lymph node pathology . However, this did not translate into longer OS [n = 781) found no benefit in OS, R0 resection, or postoperative complications with neoadjuvant chemotherapy vs. surgery alone [n = 832). Neoadjuvant radiation improved overall survival  [p < 0.001) [A meta-analysis of nine RCTs published from 1995 to 2010 assessing the benefit of neoadjuvant chemotherapy vs. surgery alone  . Periope< 0.001) .Twenty-six active clinical trials were found, as described in n = 16) are evaluating PD-1 (Programmed Death Cell Protein 1) inhibition in combination with radiation, tyrosine kinase inhibitor, HER2 inhibitor, CTLA-4 inhibitor, and fluoropyrimidine +/− taxane-based chemotherapy. PD-L1 expression varies by tumor type, with: 41% in Esophagus/GEJ SCC, 44–52% in Esophagus/GEJ AC, and 23% in Gastric AC (PD-1 or PD-L1) [The majority of these trials (r PD-L1) ,64,65,66r PD-L1) . Thus, fOne trial is designed to evaluate the benefit of HER2 inhibition with fluoropyrimidine chemotherapy. This study requires HER2 overexpression as enrollment criteria. However, similar critiques of varying levels of HER2 expression, sampling bias, and heterogeneity of tumors have been made of HER2 similarly to PD-L1 . Thus, aSeven trials are designed to evaluate various neoadjuvant chemotherapy or chemoradiation combinations to assess the following: radiation or dosage of radiation, taxane vs. fluoropyrimidine-based regimens, and benefit vs. surgery alone, amongst other aims. In SCC, trials have been designed to evaluate various combinations of treatment. Although previously evaluated, a trial will once again evaluate fluoropyrimidine-based chemoradiation vs. surgery alone. Another trial will evaluate if the benefit to survival in the CROSS trial regimen was based on the chemotherapy or the combination of chemoradiation. Further evaluating radiation, another trial will alter the dose of radiation used in the CROSS trial. Finally, another study evaluated platinum agents vs. fluoropyrimidine chemotherapy with taxane-based chemoradiation. Based on recently published results of this trial, there does not appear to be any difference in survival when comparing regimens offering the possibility of fluoropyrimidine- and taxane-based chemoradiation of patients with SCC . A futurThere are also trials that are underway utilizing therapies or techniques used in other cancer types with varying success. One trial is evaluating antiangiogenic therapy in conjunction with neoadjuvant chemotherapy. However, a previous trial using antiangiogenic therapy (bevacizumab) showed increased rates of surgical complications. Finally, a single trial is designed to evaluate the effect of neoadjuvant hyperthermic intraperitoneal chemotherapy (HIPEC). Although frequently used in the metastatic setting, the utility of this technique on resectable disease remains to be seen. The planned clinical trials will help clarify the optimal regimen in conjunction with various adjuvants, including immunotherapy, checkpoint inhibitors, targeted therapies, or intraperitoneal chemotherapy, which may be beneficial for survival in the future.Substantial progress has been made by adding neoadjuvant and perioperative therapies in various combinations in esophageal, GEJ, and gastric cancers amenable to resection. Neoadjuvant therapy has several potential advantages, including the opportunity to test a tumor’s response to a particular therapeutic regimen and tailor adjuvant therapy based on this response. Neoadjuvant therapy also has the potential to improve R0 resection rates and to improve compliance with systemic therapy. Perhaps most importantly, it provides a window to assess tumor biology, providing insight into the benefit of further medical and surgical intervention for a given patient.However, more progress is needed given the substantial rate of distant recurrence or metastases. Locoregional control may continue to be improved with patient selection and neoadjuvant and adjuvant treatment strategies. SCC of the esophagus seems to derive greater benefit from the addition of neoadjuvant radiation compared to AC. The benefit of neoadjuvant chemotherapy is clear across both esophageal AC and SCC; however, the optimal regimen is not clear. There is greater chemosensitivity to taxane-based regimens overall; however, the derived benefit individually for SCC vs. AC is not clear. Meanwhile, there appears to be greater chemosensitivity to fluoropyrimidine regimens with AC of the esophagus. This finding was used in the design of the AGITG DOCTOR trial, in which patients not responding to fluoropyrimidine treatment were offered a taxane-based regimen with and without radiation. The addition of radiation to a taxane-based regimen resulted in similar survival to the group of patients that responded to the initial fluoropyrimidine regimen, although the result was not statistically significant based on the study size. This tailored strategy may improve the outcomes of survival for patients with AC of the esophagus resulting in lower rates of local recurrence.The treatment strategy for gastric AC is centered around perioperative chemotherapy based on the results of the MAGIC and FLOT4 trials. There might be a role for neoadjuvant radiation based on the effect seen in the aforementioned meta-analysis. The impact of extended lymph node resection is controversial and may also impact survival independent of the effects of chemoradiation .Other treatment strategies that need continued exploration are immunotherapy, checkpoint inhibitors, and targeted therapy. Clinical trials are in progress assessing these in the neoadjuvant setting. Currently treated targets include EFGR, HER2, and PD-L1 ,73,74. AIn summary, there continues to be substantial progress in the neoadjuvant and perioperative treatment of distal esophageal, GEJ, and gastric cancers amenable to surgical resection. Selective addition of neoadjuvant chemotherapy and/or radiation is beneficial in specific anatomic and histopathologic subtypes. Adaptive chemoradiation may be a useful protocol using current treatment regimens. Clinical trials will provide further information on the value of immunotherapy or targeted therapies, including HER2, EFGR, PD-L1, and anti-angiogenic therapy. A distant metastatic pattern of failure remains an issue despite locoregional control, and systemic therapy will need further refinement to achieve longer survival post-surgery.


To limit the cross-sectional size of concrete structures, high-strength, lightweight concrete is preferred for the design and construction of structural elements. However, the main drawback of high-strength, lightweight concrete is its brittleness over normal-weight concrete. The ductility of concrete is a crucial factor, which plays an important role when the concrete structures are subjected to extreme situations, such as earthquakes and wind. This study aims to improve the ductility of high-strength, lightweight concrete by incorporating steel fibers. The palm oil clinker (POC)-based, high-strength, lightweight concrete specimens reinforced with steel fibers were prepared and their ductility was systematically examined. POC was used as aggregates and supplementary cementitious materials. Steel fibers from 0–1.50% (by volume), with an increment of 0.5%, were used in the concrete mix. Compression ductility, displacement ductility and energy ductility were used as indicators to evaluate the enhancement of ductility. Moreover, the compressive strength, flexural strength, stress-strain behavior, modulus of elasticity, load-displacement characteristics, energy absorption capacity and deformability of the concrete samples were investigated. The compression ductility, displacement ductility and energy ductility indexes were found to be increased by up to 472%, 140% and 568% compared to the control specimens (concrete with 0% steel fibers), respectively. Moreover, the deformability and energy absorption capacity of the concrete were increased by up to 566% and 125%, respectively. Therefore, POC-based, high-strength, fibrous, lightweight concrete could perform better than conventional concrete under extreme loading conditions as it showed significantly higher ductility. Lightweight concrete (LWC) fabrication has a significant impact on modern construction industries due to its importance in infrastructural construction worldwide ,2. LWC iAdequate ductility for high-rise buildings in earthquake-prone areas is vigorously essential ,10. MoreA lot of waste materials are produced by the palm oil manufacturing industries in the form of oil palm shell (OPS) and POC in Malaysia . MalaysiMohammed et al.  reportedTherefore, the prominent objective of the present study is to enhance the ductility performance of POC-based, high-strength, lightweight concrete comprising steel fibers of different volume fractions. The energy absorption capacity, ductility  and deformability properties are used as indicators to assess the ductility of the POC-based concrete with steel fibers.3 and 351 m2/kg, respectively.The locally available (Tasek cement ) ordinarPOC powder was utilized as supplementary bonding materials for fabricating high-strength, lightweight concrete . The POC®-2199 . Th. Th58]. The ductility and its enhancement of the fibrous, reinforced, high-strength, lightweight concrete specimens are graphically demonstrated in The energy ductility index of the POC-encompassing, fibrous, reinforced, high-strength, lightweight concrete is expressed as the ratio of the energy at the failure to the energy at the first yield of the specimen . Figure The deformability index of the POC-incorporating, fibrous, reinforced, high-strength, lightweight concrete is expressed as the ratio of the displacement at the failure to the displacement at the yield ,62. Figu(1)The compression ductility of the POC-based, high-strength, lightweight concrete with 1.0% steel fibers was six times higher compared to the control (concrete specimen with 0% steel fibers). This enhancement in ductility will significantly improve the performance of high-strength, lightweight concrete structures under earthquake and wind loading.(2)The addition of steel fibers to the POC-based, high-strength, lightweight concrete triggered an increase in displacement ductility of up to approximately 140% over the control specimen. Moreover, the energy ductility of the POC-based, high-strength, lightweight concrete was increased by up to 568% compared to that of the control specimen.(3)The deformability of the concrete corresponding to the peak stress increased by up to 566% owing to the addition of the steel fibers. The enhancement of the deformability of the high-strength, lightweight concrete causes a ductile failure of the concrete structures under extreme conditions.(4)Although the 28-day compressive strength of the POC-based, high-strength, lightweight concrete increased by up to 19%, the flexural strength increased from 5.5 MPa to 15.17 MPa. This significant improvement of the flexural strength of the POC-based, high-strength, lightweight concrete results in a substantial increase in the cracking moment capacity of the structural elements.(5)The modulus of elasticity and the energy absorption capacity of the POC-based, high-strength, lightweight concrete increased by up to 40% and 125%, respectively.(6)Overall, the ductility and mechanical properties of the POC-based, high-strength, lightweight concrete were substantially enhanced because of the addition of hook-end steel fibers.This study reveals improved ductility behavior and mechanical properties of palm oil clinker (POC)-based, high-strength, lightweight concrete incorporating hook-end steel fibers . Based on the experimental results, the following conclusions can be drawn: