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Crude oil is a complex system with unique physical and chemical properties. One of the most important physical properties of crude oil is viscosity. This paper demonstrates that the temperature dependence of crude oil viscosity can be described using the universal scaling model for viscosity over a wide temperature range. For the first time, a correlation has been established between the API gravity of crude oil and the fragility index, which is a measure of viscosity change with temperature in the glass transition region. It has been demonstrated that this correlation can be replicated by a linear function: the higher the API gravity the lower the oil density and the poorer the oil forms an amorphous state. The temperature range has been determined, at which molecular cooperation in crude oil can occur. The obtained results allow us to estimate/predict the viscosity of any crude oil at low temperatures, correlated with the glass transition temperature, based on high temperature experimental measurements near the melting point. [ABSTRACT FROM AUTHOR]

Background: Esophageal cancer remains a significant global health challenge. Several treatment modalities were explored in randomized controlled trials (RCTs) in recent decades. This study evaluates the robustness of RCTs focusing on esophageal cancer treatment using the fragility index (FI) and reverse fragility index (RFI). Methods: A systematic review of RCTs studying different treatment modalities for esophageal cancer from 2000 to 2023 was conducted. The FI and RFI were utilized to gauge the robustness of statistically significant and non-significant outcomes, respectively. The FI represents the minimal number of patient outcomes that would need to alter to overturn a trial's statistical significance, while RFI indicates the minimal changes required to achieve significance in non-significant results. Results: Out of 4028 studies retrieved, 21 RCTs were included for final analysis. The studies spanned 2001 to 2023 with a mean followup of 66 months (range, 29–108 months) and median number of patients of 194 (range, 45–802). The most common treatment modalities examined in these studies were neoadjuvant chemoradiotherapy (n = 7, 33.3%), neoadjuvant chemotherapy (n = 4, 19.0%), and neoadjuvant immunotherapy (n = 2, 9.5%). Only 5 studies (23.8%) had a statistically significant primary outcome result with a median FI of 6 (IQR, 2.5–8.5). Non-significant primary outcomes were seen in 16 studies (76.2%) with a median RFI of 4 (IQR 1–11) and lost to followup of 0 (IQR 0–4). In the study with the highest FI (10), the FI was lower than the number of patients lost to followup (13). Conclusion: Our findings demonstrate that most RCTs on esophageal cancer treatments did not report significant primary outcomes. The few studies that reported significant results had a low fragility index, suggesting a vulnerability in their findings. [ABSTRACT FROM AUTHOR]

Purpose: FDA investigational device exemption (IDE) studies are considered a gold standard of assessing safety and efficacy of novel devices through RCTs. The fragility index (FI) has emerged as a means to assess robustness of statistically significant study results and inversely, the reverse fragility index (RFI) for non-significant differences. Previous authors have defined results as fragile if loss to follow up is greater than the FI or RFI. The aim of this study was to assess the FI, RFI, and robustness of data supplied by IDE studies in spinal surgery. Methods: This was a systematic review of the literature. Inclusion criteria included randomized controlled trials with dichotomous outcome measures conducted under IDE guidelines between 2000 and 2023. FI and RFI were calculated through successively changing events to non-events until the outcome changed to non-significance or significance, respectively. The fragility quotient (FQ) and reverse fragility quotient (RFQ) were calculated by dividing the FI and RFI, respectively, by the sample size. Results: Thirty-two studies met inclusion criteria with a total of 40 unique outcome measures; 240 outcomes were analyzed. Twenty-six studies reported 96 statistically significant results. The median FI was 6 (IQR: 3-9.25), and patients lost to follow up was greater than the FI in 99.0% (95/96) of results. The average FQ was 0.027. Thirty studies reported 144 statistically insignificant results and a median RFI of 6 (IQR: 4-8). The average RFQ extrapolated was 0.021, and loss to follow up was greater than the RFI in 98.6% (142/144) of results. Conclusions: IDE studies in spine surgery are surprisingly fragile given their reputations, large sample sizes, and intent to establish safety in investigational devices. This study found a median FI and RFI of 6. The number of patients lost to follow-up was greater than FIand RFI in 98.8% (237/240) of reported outcomes. FQ and RFQ tell us that changes of two to three patients per hundred can flip the significance of reported outcomes. This is an important reminder of the limitations of RCTs. Analysis of fragility in future studies may help clarify the strength of the relationship between reported data and their conclusions. [ABSTRACT FROM AUTHOR]

Purpose: This study employs both the fragility index (FI) and fragility quotient (FQ) to assess the level of robustness in the cervical disc arthroplasty (CDA) literature. We hypothesize that dichotomous outcomes involving CDA would exhibit statistical vulnerability. Methods: A PubMed search was conducted to evaluate dichotomous data for randomized controlled trials (RCTs) in CDA literature from 2000 to 2023. The FI of each outcome was calculated through the reversal of a single outcome event until significance was reversed. The FQ was calculated by dividing each fragility index by the study sample size. The interquartile range (IQR) was also calculated for the FI and FQ. Results: Of the 1561 articles screened, 111 met the search criteria, with 35 RCTs evaluating CDA included for analysis. Six hundred and ninety-three outcome events with 130 significant (P < 0.05) outcomes and 563 nonsignificant (P ≥ 0.05) outcomes were identified. The overall FI and FQ for all 693 outcomes were 5 (IQR 3–7) and 0.019 (IQR 0.011–0.043). Fragility analysis of statistically significant outcomes and nonsignificant outcomes both revealed an FI of 5. All of the studies reported loss to follow-up (LTF) data where 65.7% (23) did not report or reported an LTF greater or equal to 5. Conclusions: The literature regarding CDA RCTs lacks statistical robustness and may misrepresent the conclusions with the sole use of the P value. By implementing the FI and FQ along with the P value, we believe the interpretation and contextualization of the clinical data surrounding CDA will be better understood. [ABSTRACT FROM AUTHOR]

Purpose: To identify and assess the clinical impact of randomised controlled trials (RCTs) assessing the surgical management of femoroacetabular impingement syndrome (FAIS) through a citation analysis. Methods: MEDLINE, EMBASE and CENTRAL were searched from inception to April 22, 2023 for RCTs assessing the surgical management of FAIS. Study characteristics were directly abstracted from included trials and citation metrics were obtained from the Clarivate Web of Knowledge database on May 19, 2023. The continuous fragility index (CFI) was calculated for eligible outcomes. Univariate regression models were used to explore correlations between total citations per year and various study characteristics. Results: Ten studies comprising one thousand two hundred ninetypatients were eligible for analysis. Studies were published from 2013 to 2023. Eight countries were represented across various trials with 91% being either North American or European. The mean journal impact factor of published studies was 39.684 (median 2.982; range 1.31–202.73). The mean citation density was 14.17 (range 0.33–48.67). The median CFI was 4.8 (range 1–32.2). Correlation analysis demonstrated strong and statistically significant correlations to study sample size (R = 0.75, p = 0.012), journal impact factor (R = 0.80, p = 0.006) and continuous fragility index (R = 0.95, p = 0.015). Conclusion: Trials assessing the surgical management of FAIS present with a wide range of clinical uptake based on citation density and are published in journals of broadly variable impact factor. Despite promising citation metrics, high-quality evidence on arthroscopy for FAIS is limited to the United States and Europe with an unclear international impact. Future knowledge translation efforts are warranted to maximise the international uptake of evidence regarding arthroscopic management of FAIS. Level of evidence: I. [ABSTRACT FROM AUTHOR]

Purpose: To report the statistical stability of prospective clinical trials evaluating the effect of intramedullary reaming on rates of non-union in tibial fractures through calculation of the fragility metrics for non-union rates and all other dichotomous outcomes. Methods: Literature search was conducted for prospective clinical trials evaluating the effect of intramedullary reaming on non-union rates in tibial nailing. All dichotomous outcomes were extracted from the manuscripts. The fragility index (FI) and reverse fragility index (RFI) were calculated by determining the number of event reversals required for a statistically significant outcome to lose significance and vice-versa. The fragility quotient (FQ) and reverse fragility quotient (RFQ) were calculated by dividing the FI or RFI by the sample size, respectively. Outcomes were defined as "fragile" if the FI or RFI was found to be less than or equal to the number of patients lost to follow-up. Results: Literature search identified 579 results which produced ten studies meeting the criteria for review. There were 111 outcomes identified for analysis, of which 89 (80%) exhibited statistical fragility. For reported outcomes across the studies the median and mean FI was 2, the median FQ was 0.019, the mean FQ was 0.030, the median RFI was 4, the mean RFI was 3.95, the median RFQ was 0.045, and the mean RFQ was 0.030. Four studies reported outcomes which were found to have an FI of 0. Conclusions: The studies evaluating the effect of intramedullary reaming on tibial nail fixation demonstrate considerable fragility. On average, two event reversals for significant findings, and four event reversals for insignificant findings are sufficient to alter statistical significance. Level of evidence: Level II, systematic review of Level I and Level II studies. [ABSTRACT FROM AUTHOR]

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Purpose: The purpose of this study was to apply both the fragility index (FI) and fragility quotient (FQ) to evaluate the degree of statistical fragility in the distal femur fracture (DFF) literature. We hypothesized that the dichotomous outcomes within the DFF literature are statistically fragile. Methods: Using preferred reporting items for systematic reviews and meta-analyses, we performed a PubMed search for distal femur fractures clinical trials from 2000 to 2022 reporting dichotomous outcomes. The FI of each outcome was calculated through the reversal of a single outcome event until significance was reversed. The FQ was calculated by dividing each fragility index by study sample size. The interquartile range (IQR) was also calculated for the FI and FQ. Results: Of the 4258 articles screened, 92 met the search criteria, with eleven RCTs included for analysis. Ninety eight outcome events with 25 significant (P < 0.05) outcomes and 73 nonsignificant (P > 0.05) outcomes were identified. The overall FI and FQ for all 98 outcomes were 5 (IQR 4–6) and 0.130 (IQR 0.087–0.174), respectively. Three studies (33.3%) reported loss to follow (LTF) greater than 5. Conclusions: The randomized controlled trials in the peer-reviewed distal femur fracture literature may not be as robust as previously thought, as incorporating statistical analyses solely on a P value threshold is misleading. Standardized reporting of the P value, FI and FQ can help the clinician reliably draw conclusions based on the fragility of outcome measures. [ABSTRACT FROM AUTHOR]

In the present paper, the study of amorphous-crystalline transformation in (Se80Te20)94−x Ge6Bix (x = 0, 1, 2, 4, 6, 8, 10 and 12 at.%) chalcogenide alloys has been done using non-isothermal differential scanning calorimetry (DSC). Characteristic temperatures indicate that the samples with x = 1 at.% and x = 6 at.% can be considered as a critical configurations at which the system becomes a chemically ordered alloy. Kissinger and Moynihan approaches which utilized dependence of glass transition temperature (Tg) on heating rate (α) are used to deduce activation energy of glass transition (Eg). Crystallization process is characterized by various kinetic parameters such as activation energy and frequency factor deduced using different methods. Dietzel, Hruby, Saad and Poulin criteria are employed to assess glass forming ability and thermal stability of investigated alloys. The alloy with x = 12 at.% of Bi content has highest ∆T confirms maximum thermal stability, further validated from the values of Hruby parameter (Kgl) and thermal stability parameter (S). The fragility index infers that the composition studied in the present study is made from strong glass forming liquids. [ABSTRACT FROM AUTHOR]

In this paper we derive a characterization of the distribution of the number of exceedances among the components of a random vector in terms of order statistics of generators of D-norms (GOD). The computation of the fragility index is an immediate consequence. [ABSTRACT FROM AUTHOR]

Thermal characterization of different compositions of Ge30−xSbxTe10Se60 (x = 0, 5, 10, 15, 20 at.%) glassy materials has been investigated through differential scanning calorimetry (DSC). The tested glasses have been synthesized by melt-quench technique. Glassy materials display compositional phase separation at x = 0, 5, 10, 15 at.%. For additional increase in Sb content at x = 20 at.%, the separation of phases combines in the glass matrix. The glass transition temperature (Tg), initial temperature of crystallization (Tc), peak crystallization temperature (Tp) and melting temperature (Tm) were found to be affected by both heating rate and composition. It is noticed that the increasing of antimony mass percentage in the glassy matrix is leading to decrease in Tg, Tc, Tp and Tm values. The melting temperature (Tm) of these glasses was found in the range 733–746 K for the first phase and in the range 740–792 K for the second phase. The activation energy of glass transition (Eg), activation energy for crystallization (Ec), Avrami index (n) and fragility index (Fi) were calculated using these specific temperatures. Eg decreases with increasing Sb content in all studied samples, but Eg is increasing in the sample with Sb content of 20%, and hence, it varies between 102.7 and 110.6 kJ approximately, whereas (Ec) decreases with the increase in the Sb content in all the tested samples and varies between 283 and 339 kJ. The fragility index varies between 10 and 26 indicating that the melts of these glasses are strong, and the fragility is minimum. The results were discussed in terms of the average coordination number NC and chemical bond approach. [ABSTRACT FROM AUTHOR]

Background: Utility of robotic over laparoscopic approach has been an area of debate across all surgical specialties over the past decade. The fragility index (FI) is a metric that evaluates the frailty of randomized controlled trials (RCTs) findings by altering the status of patients from an event to non-event until significance is lost. This study aims to evaluate the robustness of RCTs comparing laparoscopic and robotic abdominopelvic surgeries through the FI. Methods: A search was conducted in MEDLINE and EMBASE for RCTs with dichotomous outcomes comparing laparoscopic and robot-assisted surgery in general surgery, gynecology, and urology. The FI and reverse fragility Index (RFI) metrics were used to assess the strength of findings reported by RCTs, and bivariate correlation was conducted to analyze relationships between FI and trial characteristics. Results: A total of 21 RCTs were included, with a median sample size of 89 participants (Interquartile range [IQR] 62–126). The median FI was 2 (IQR 0–15) and median RFI 5.5 (IQR 4–8.5). The median FI was 3 (IQR 1–15) for general surgery (n = 7), 2 (0.5–3.5) for gynecology (n = 4), and 0 (IQR 0–8.5) for urology RCTs (n = 4). Correlation was found between increasing FI and decreasing p-value, but not sample size, number of outcome events, journal impact factor, loss to follow-up, or risk of bias. Conclusion: RCTs comparing laparoscopic and robotic abdominal surgery did not prove to be very robust. While possible advantages of robotic surgery may be emphasized, it remains novel and requires further concrete RCT data. [ABSTRACT FROM AUTHOR]

To characterize the fragility index (FI) of statistically significant results reported in randomized controlled trials (RCTs) investigating the incidence of hemidiaphragmatic paralysis (HDP) after brachial plexus blocks. A systematic review of RCTs retrieved from the PubMed-Medline, Embase, and Web of Science electronic databases was conducted. All alternative RCTs published between January 2012 and October 2022 were identified. Only RCTs with two parallel arms designs, and reporting HDP as the primary outcome, statistical significance, and superiority results were selected. The FI was calculated according to Fisher's exact test using previously described methods. In addition, the risk of bias was evaluated using the Cochrane Risk-of-Bias tool for randomized trials. The 23 RCTs that fulfilled the inclusion criteria had a median FI of 4 (interquartile range [IQR]2–8) and a median Fragility Quotient of 0.077 (IQR 0.038- 0.129). However, in 13 (56.5%) trials, the calculated FI value was ≤ 4. In 3/23 (13.0%) trials, the number of patients who dropped-out exceeded the FI value. Most trials (91.3%) had an overall low risk of bias. This systematic review revealed that the statistical results of RCTs investing HDP after brachial plexus blocks have tended to be fragile in the past decade. The FI should be an important aid in the interpretation of clinical results in combination with the P-value, particularly when statistically significant results are dependent on a small number of events. Future RCTs with larger sample sizes are needed to obtain more robust results in this field. [ABSTRACT FROM AUTHOR]

While randomized controlled trials (RCTs) are regarded as one of the highest forms of clinical research, the robustness of their P values can be difficult to ascertain. Defined as the minimum number of patients in a study arm that would need to be changed from a non-event to event for the findings to lose significance, the Fragility Index is a method for evaluating results from these trials. This study aims to calculate the Fragility Index for trials evaluating perioperative esophagectomy-related interventions to determine the strength of RCTs in this field. MEDLINE and EMBASE were searched for RCTs related to esophagectomy that reported a significant dichotomous outcome. Two reviewers independently screened articles and performed the data extractions with risk of bias assessment. The Fragility Index was calculated using a two-tailed Fisher's exact test. Bivariate correlation was conducted to evaluate associations between the Fragility Index and study characteristics. 41 RCTs were included, and the median sample size was 80 patients [Interquartile range (IQR) 60–161]. Of the included outcomes, 29 (71%) were primary, and 12 (29%) were secondary. The median Fragility Index was 1 (IQR 1–3), meaning that by changing one patient from a non-event to event, the results would become non-significant. Fragility Index was correlated with P value, number of events, and journal impact factor. The RCTs related to esophagectomy did not prove to be robust, as the significance of their results could be changed by altering the outcome status of a handful of patients in one study arm. [ABSTRACT FROM AUTHOR]

Present communication reports the crystallization and glass transition kinetics of xBi2O3–(50 − x)ZnO–50V2O5 glass system using the non-isothermal method of differential scanning calorimetry. The activation energies for crystallization (Ec) and glass transition (Eg) have been extracted from the fitting of various theoretical models with experimental data. The values of Ec and Eg for the studied glass samples lie in the range of 158.60–223.74 kJ mol−1 and 406.06–479.23 kJ mol−1, respectively. The activation energies of crystallization extracted from the fitting of experimental data with Avrami's equation and the Augis–Bennet model are in close agreement. The thermal stability of studied glass compositions has been analysed in the light of various parameters, viz. temperature difference (∆T), Hruby parameter (Hr), full width at half maximum of crystallization peak, frequency factor (ν), configurational constant (B), fraction of fluctuation free volume (fg) and thermal expansion coefficient (αf). It has been observed that volume nucleation occurs in the glass system under reference. The studied glass compositions are of low fragile nature, having a fragility index (m) ~ 40. [ABSTRACT FROM AUTHOR]

Introduction: The role of medical expulsive treatment (MET) is controversial. Fragility index is an additional metric to assess randomized controlled trials (RCTs) outcome validity and indicates how many patients would be required to convert a trial from being statistically significant, to not significant. The larger is the FI, the better the trial's data. The aim of this study is to assess FI of RCTs regarding MET for ureteral stones. Materials and methods: A systematic literature search was performed. RCTs, reporting stone expulsion as a dichotomous outcome, showing statistical significance were eligible. FI (the number of patients needed to change from a non-event to event group, to lose statistical significance) and Fragility quotient (FI divided by total sample size), were calculated while Pearson's correlation and Mann–Whitney U test were used as appropriate. Results: Thirty-six RCTs were eligible, with median FI = 3.5 and fragility quotient = 0.042, median sample size = 81, median journal impact factor = 1.73 and median reported p value = 0.008. In 33.3% of the studies, number of patients lost during follow-up was larger than FI, while in 13.89% of the studies, FI was 0, indicating use of inappropriate statistical method. Pearson's correlation showed significant positive association between FI and sample size (r = 0.981), number of events (r = 0.982) and impact factor (r = 0.731), while no association was found with p value or publication year. Conclusions: In this analysis, a calculated FI of 3.5 indicates that findings from RCTs on MET for ureteral stones are fragile and should be interpreted in combination with clinical thinking and expertise. [ABSTRACT FROM AUTHOR]

Summary: This is the first report on the fragility of results from randomized controlled trials (RCTs) for the treatment of osteoporosis. The results of aforementioned RCTs appear to depend on a small number of events and are generally statistically fragile. Introduction: Osteoporosis remains a health concern worldwide. Evidence-based guideline recommendations that are mainly based on results of clinical trials are important to clinical decision-making. The fragility index (FI) is a novel statistical metric to measure the fragility of results from an RCT. Our study aimed to analyze the fragility of the clinical trials referenced in the guidelines for the treatment of osteoporosis. Methods: Trials were included if they investigated primary osteoporosis, randomized patients to treatment or control in a 1:1 design, and reported fracture outcome as the primary endpoint. The FI and fragility quotient (FQ) were calculated for assessing the robustness of results from the eligible RCTs. An FI was defined as the minimum number of events in the intervention group that needs to change from a non-event to an event in order to render a significant result non-significant (or vice versa). The FQ was calculated by dividing the FI by the sample size of the trial. Results: Of the 372 RCTs identified from the guidelines, 42 were eligible for analyses. Their median FI was 10 (25th–75th percentile [Q1-Q3]: 4–18), with a median FQ of 0.007 (Q1-Q3: 0.0017–0.019). Approximately one third of the RCTs had a FI of less than or equal to 5. There were 17 (40.5%) trials where the number of patients lost to follow-up was greater than the FI. The FI was significantly associated with sample size, journal impact factor, and the percent of patients lost to follow-up. Conclusion: Results from some RCTs supporting guideline recommendations for the treatment of osteoporosis depend on a small number of events. The FI and FQ may provide additional, intuitive metrics to help interpret the robustness of trial results. [ABSTRACT FROM AUTHOR]

Purpose: Meta-analyses occupy the highest level of evidence and thereby guide clinical decision-making. Recently, randomised-controlled trials were evaluated for the robustness of their findings by calculating the fragility index. The fragility index is the number of events that needs to be added to one treatment arm until the statistical significance collapses. We, therefore, aimed to evaluate the robustness of paediatric surgical meta-analyses.Methods: We searched MEDLINE for paediatric surgical meta-analyses in the last decade. All meta-analyses on a paediatric surgical condition were eligible for analysis if they based their conclusion on a statistically significant meta-analysis.Results: We screened 303 records and conducted a full-text evaluation of 60 manuscripts. Of them, 39 were included in our analysis that conducted 79 individual meta-analyses with significant results. Median fragility index was 5 (Q25-Q75% 2-11). Median fragility in relation to included patients was 0.77% (Q25-Q75% 0.29-1.87%).Conclusion: Paediatric surgical meta-analyses are often fragile. In almost 60% of results, the statistical significance depends on less than 1% of the included population. However, as the fragility index is just a transformation of the P value, it basically conveys the same information in a different format. It therefore should be avoided. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are neoteric solvents characterized by unique physicochemical properties and considerable structural variability. The thermal behavior of 24 ILs, belonging to two structurally related families with either bromide or Tf2N as counteranion, was analyzed. For bromide mono- and dicationic ionic liquids (DILs), thermal gravimetric analysis showed similar decomposition events, with only small gain in stability for a few members of the latter class. Conversely, all Tf2N DILs displayed higher stabilities (up to 34 K) than the corresponding monocations, thus highlighting the different role played by the two counteranions. Mono- and dicationic ILs bearing a reactive group on the imidazolium substituent resulted instead the least stable ILs studied. Differential scanning calorimetry analyses of most of the (D)ILs only showed glass transition temperatures, a behavior in agreement with the broad liquid range of ILs. The impact of the cationic structure and/or of the type of anion on the above-mentioned transition temperatures has been studied. The apparent activation energy (Ea) and the fragility index (m) for some (D)ILs have also been obtained. Finally, a few bromide (D)ILs presented peculiar thermal events. [ABSTRACT FROM AUTHOR]

The goal of this manuscript was to apply the fragility index (FI), which is a statistically sound method to evaluate robustness of test results, to liver-related randomized clinical trials. The authors searched the ClinicalTrials.gov database with the following limitations: term "liver," recruitment completed, with results, interventional study type, last updated May 01, 2016, to May 01, 2017. Forty-eight trials were included and four had FI of 0. The median FI for trials moving from significance to non-significance was 6 (IQR 18; 2 to 20), while the median for trials moving from non-significance to significance was 5 (IQR 5; 4 to 9). The median number lost to follow up was 17 (IQR 42; 3 to 45). Of the 21 trials that showed statistical significance, the number lost to follow up was greater than the FI in 13 (61.90%) trials. Investigators of liver-related studies should consider adding the FI to evaluate their work. [ABSTRACT FROM AUTHOR]

HIV/AIDS is associated with significant morbidity, mortality, and financial burden. For these reasons, robust clinical evidence is critical. We aim to investigate the fragility index, fragility quotient, and risk of bias of clinical trial endpoints in HIV medicine. The fragility index represents the minimum amount of trial endpoint "nonevents" changed to "events" in one trial arm required to nullify statistical significance. The fragility quotient contextualized the fragility index by dividing the index by the total trial sample size. We selected eligible trials from the Department of Health and Human Services guideline for the use of antiretroviral agents in HIV-1-infected adults and adolescents. We calculated the fragility index and fragility quotient for all included trials. The Cochrane "risk of bias" Tool 2.0 was used to evaluate the likelihood and sources of bias in the included trials. Thirty-nine RCTs were included for our analysis of fragility. Thirty-six were included for our analysis of the risk of bias. The median fragility index was 5. Three RCTs were at high risk of bias, all due to the selection of the endpoint or statistical test. Twenty had some concerns for risk of bias. The analyzed HIV medicine RCT endpoints were fragile, overall. This indicates that a median of 5 patients across all included studies would nullify the statistical significance of the endpoints. Furthermore, we found evidence that concerns for bias are present at a high rate. [ABSTRACT FROM AUTHOR]

Fragility of randomized controlled trials (RCTs) has been evaluated using a novel metric called fragility index (FI), which measures how many events the statistical significance of a dichotomous outcome depends on. This study aimed to evaluate the fragility of RCTs in intracranial hemorrhage. Literature search (PubMed/Embase) identified all RCTs of intracranial hemorrhage since 2006. The overall distribution of FI was evaluated. Subgroup and spearman correlation analyses were made to explore potential factors that may affect FI value. All the included RCTs were divided into two groups (positive and negative trials) according to the statistical significance of selected outcomes. Finally, 47 positive and 51 negative trials were included. Both the median FI ([2; IQR, 1-4] vs. [6; IQR, 4-9], p < 0.001) and the proportion of trials with FI ≤1 (2 vs. 18, p < 0.001) in positive trials were smaller than negative trials. In subgroup comparison within positive trials, sample size ([165; IQR, 87-200] vs. [83; IQR, 60-120], p = 0.015) and number of events ([35; IQR, 20-72] vs. [24; IQR, 11-32], p = 0.015) were higher in subgroup with FI >1 than the subgroup with FI ≤1. Weak positive correlations were found between FI and sample size and number of events. In the field of intracranial hemorrhage, trials reporting significant conclusions often depend on a small number of events. Compared to sample size, this phenomenon is more likely to be affected by statistical approach and trial methodology. [ABSTRACT FROM AUTHOR]

Herein, a urethane-based photo-polymeric network containing low content of amine-modified graphene sheets (GSs) was characterized. Scanning electron microscopy (SEM), wide-angle X-ray diffraction and Fourier transform infrared spectroscopy were used to investigate the morphological properties of the modified GSs. SEM, atomic force microscopy (AFM) and dynamical mechanical analysis techniques were also employed to study the physico-mechanical properties of the photo-polymeric network containing amine-functionalized GSs. We showed that amine groups attached to the GSs can lead to a new interfacial stress concentrator layer around GSs. This new interfacial layer formation was explained on the basis of the oxygen-scavenging effect of the amine groups. Also, by using AFM data the thickness of the high-modulus interfacial layer was estimated to be between 1 and 3 microns. Furthermore, the dynamic fragility index and the cooperatively rearranging (CRR) size corresponding to the highly cross-linked interfacial layer were found to be 74 and 6, respectively. The dynamic fragility index of the nano-gel particle was also obtained to be the lowest (37). Finally, it was shown that the incorporation of amine-modified GSs into the photo-polymeric network not only can offer higher dissipation factor but also increases the temperature corresponding to the maximum damping factor. [ABSTRACT FROM AUTHOR]

Glassy Se100−x(Ge2Sb2Te5)x (x = 5, 10, 15 and 20) bulk alloys were prepared by melt-quenched technique and studied by using differential scanning calorimetry at different heating rates under non-isothermal condition. The detailed thermal analysis shows that the glass transition temperature (Tg) depends on heating rates and x content. In particular, it is found that the glass-forming ability, thermal stability (Tc − Tg) and crystallization activation energy (Ec) increase with increased x content in amorphous Se, whereas glass transition activation energy (Eg) and fragility index (F) decrease with increased x contents. Variation in these parameters can be explained on the basis of network-forming ability of Se and bonding arrangement among the constituent atoms of alloys. [ABSTRACT FROM AUTHOR]

The glass transition temperature dependence on a heating rate was investigated by differential scanning calorimetry for chalcogenide glasses from the Agx(As2(S0.5Se0.5)3)100−x system for x = 0, 0.5, 2 and 3 at.%. According to this dependence, apparent glass transition activation energies Eg were calculated for differently defined glass transition temperatures (onset Tg1, midpoint Tg2, endpoint Tg3 and endset Tg4). Also, Eg was analysed using isoconversional (model free) method. The results showed that the activation energy is not constant during the investigated process and vary with the extent of transformation from the glassy to the supercooled phase, pointing out that a complicated, multi-step process occurs. Eg decreases from about 340 to 200 kJ mol−1 in the composition with 2 at.% of silver. The values of the fragility index showed that these glasses do not exhibit large configuration changes during the glass transition process. Influence of silver content on investigated parameters was discussed. Apparent glass transition activation energy, variability parameter and fragility index showed a significant change in their values for the composition with 3 at.% of silver. Application of the isoconversion model for determination of apparent glass transition activation energy has showed that this parameter (at extent of conversion of 0.5) decreases from about 260 kJ mol−1 for x = 0, 0.5, 2 at.% to about 185 kJ mol−1 for x = 3 at.% of silver content. Likewise, fragility parameter drops from ~ 28.5 for x = 0, 0.5, 2 at.% to 21.5 x = 3 at.% of silver. [ABSTRACT FROM AUTHOR]

This work aims to research the glass transition kinetics aspects for Se60Ge15As25 and Se60Ge15Sn25 compositions, utilized differential thermal analysis technique under the non-isothermal condition at various heating rates. Glass transition temperature (Tg) has been discovered heating rate and composition dependence. Composition reliance of Tg can be comprehended with the correlation between Tg and coordination number and mean bond energy also for the investigated compositions. Heating rate dependence of Tg reveals the activation energy of glass transition (Eg) values according to various methods for Tg with various definitions. The estimated Eg values have been discovered enlarging with temperature throughout the glass transition region. The relative error (e %) for Kissinger’s activation energy and its related parameters have been resolved and discussed. The correlation between glass transition and crystallization temperatures reveals that the crystallization process is more sensitive to heating rate than glass transition process. The critical heating rate value reflects that the Se60Ge15As25 composition is the most thermal stable composition. Fragility index values have been assessed by various relations and categorized the compositions under review as strong glasses. [ABSTRACT FROM AUTHOR]

The nature of glass transitions in chalcogenides and modified oxides depends on the network mean coordination number $\langle r\rangle$. These display systematic trends when spanning across the three topological phases: flexible, intermediate, and stressed-rigid. Trends in the glass-transition temperature Tg($\langle r\rangle$) show a monotonic increase with $\langle r\rangle$, but the nonreversing enthalpy of relaxation at Tg, ΔHnr($\langle r\rangle$), shows a deep- and square-well-like minimum with the walls representing the rigidity and stress transitions with increasing $\langle r\rangle$, respectively. In the well, the ΔHnr($\langle r\rangle$) term remains minuscule (∼0) corresponding to the isostatically rigid intermediate phase (IP). The melt fragility index (m) shows rather low values, m($\langle r\rangle$) < 20 for IP compositions, but increases outside the IP. Glass compositions in the IP show absence of network stress, form compacted networks, possess thermally reversing glass transitions, and display high glass-forming tendency—functionalities that have attracted widespread interest in understanding the physics of glasses and applications of the new IP formed. [ABSTRACT FROM PUBLISHER]

The calorimetric parameters of glassy SeCdIn ( x = 0, 2, 6 and 10) alloys were investigated using differential scanning calorimetry (DSC) under non-isothermal conditions at different heating rates of 5, 10, 15 and 20 K min. The composition dependencies of activation energy of glass transitions ( E), crystallization activation energy ( E), fragility index ( F), Hruby number ( K) and rate constant ( K) were evaluated from DSC curves. Results indicate that kinetic parameter varies with In content in Cd-Se glassy matrix. It is observed that crystallization activation energy ( E) and K are minimum and K is maximum for SeCdIn glass. Therefore, SeCdIn glass is the most thermally stable glass and has highest glass-forming ability in this series. It can be explained by chemical bond theory of solids. [ABSTRACT FROM AUTHOR]

Glass-transition kinetics of $$\mathrm{Se}_{80}\mathrm{In}_{20-\mathrm{x}}\mathrm{Pb}_{\mathrm{x}}$$ ( $$x =$$ 0, 5, 10, and 15) chalcogenide glasses have been carried out at different heating rates by using differential scanning calorimeter (DSC) under the non-isothermal condition. The glass-transition temperature $$T_{\mathrm{g}}$$ and peak glass-transition temperature $$T_{\mathrm{pg}}$$ have been determined from DSC thermograms. The reduced glass temperature $$T_{\mathrm{rg}}$$ , total relaxation time $$\tau _{T_{g}}$$ thermal-stability parameters $$K^{l}$$ and $$S$$ , the activation energy of glass transition $$E_{\mathrm{g}}$$ , the fragility index $$F_{\mathrm{i}}$$ , and the average coordination number $$\langle Z\rangle $$ have been calculated on the basis of the experimental results. The temperature differences $$(T_{\mathrm{c}}-T_{\mathrm{g}}), K_{\mathrm{gl}}, K^{l}, S$$ , and $$E_{\mathrm{g}}$$ are found to be maxima for $$\mathrm{Se}_{80}\mathrm{In}_{10}\mathrm{Pb}_{10}$$ glass. This indicates that $$\mathrm{Se}_{80}\mathrm{In}_{10}\mathrm{Pb}_{10}$$ glass has the highest thermal stability and glass-forming ability in the investigated compositional range. These results could be explained on the basis of modification of the chemical bond formation due to incorporation of Pb in the Se-In glassy matrix. [ABSTRACT FROM AUTHOR]

In this study, the kinetics of glass transitions of TiCuNi and FeCoBSi metallic glasses are studied using thermal analysis technique, i.e., differential scanning calorimetry, by means of continuous heating of the sample at various heating rates. In the present study, based on the heating rate dependence of glass transition temperature ( T), the activation energy ( E) of the glass transition region is determined by two most frequently used approaches, i.e., Moynihan's method and Kissinger's equation. The fragility index, m, is also calculated using T, which is a measure of glass-forming ability of the given system. The result shows that the fragility index, m, of the given systems is <16. This indicates that the given systems are strong liquids with excellent glass-forming ability. [ABSTRACT FROM AUTHOR]

We consider a random vector X, whose components are neither necessarily independent nor identically distributed. The fragility index (FI), if it exists, is defined as the limit of the expected number of exceedances among the components of X above a high threshold, given that there is at least one exceedance. It measures the asymptotic stability of the system of components. The system is called stable if the FI is one and fragile otherwise. In this paper, we show that the asymptotic conditional distribution of exceedance counts exists, if the copula of X is in the domain of attraction of a multivariate extreme value distribution, and if the marginal distribution functions satisfy an appropriate tail condition. This enables the computation of the FI corresponding to X and of the extended FI as well as of the asymptotic distribution of the exceedance cluster length also in that case, where the components of X are not identically distributed. [ABSTRACT FROM AUTHOR]

The dynamic mechanical properties of a (Zr77.5Ti22.5)55(Ni48Cu52)21.25Be23.75 amorphous alloy were investigated by frequency-dependent elastic moduli and isothermal multi-frequency measurements. The frequency-dependent loss modulus showed a relaxation behavior resulting from a glass transition, and the variation of the peak frequency was related to the Arrhenius equation. Isothermal multi-frequency measurement data were used to construct the master curves of the elastic moduli and tan δ by applying the time-temperature superposition principle. The temperature dependence of the shift factor was found to follow the Arrhenius relationship, and the activation energies for the low temperature relaxation and glass transition were approximately 156.6kJ/mol and 554kJ/mol, respectively. The glass transition temperature ( T g) was manifested by the crossover region of the shift factor dependence, and from the relationship between the shift factors and the temperature above T g), the fragility index of this alloy was estimated. [ABSTRACT FROM AUTHOR]

The present study aimed to apply fragility index ( m) of polymers in the determination of the optimal amount of plasticizer in polymer films. The fragility index of different Eudragit polymers (RS, RL, EPO) was assessed by differential scanning calorimerty (DSC), applying the Arrhenius connection (log q–1/ T g). The fragility of Eudragit EPO films proved to be the highest, while in the case of RS and RL, the increase of the alkyl-chain length caused the increase of fragility. Studying the effect of plasticizer (triethyl citrate, TEC) on the m value of Eudragit RL and RS films, a near linear reduction of the fragility index could be observed between 5–30% TEC concentration, but above 30%, this value leveled out to constant. [ABSTRACT FROM AUTHOR]

Thermodynamic and dynamic data of the four pentitols, xylitol, adonitol, l-arabitol and d-arabitol, measured by temperature modulated DSC (TMDSC) in the crystalline and amorphous states are presented. The properties of the supercooled liquids clearly show two distinct kinds of thermal behaviors with regard to their aptitude to crystallize. The capacity of the TMDSC technique to characterize both the molecular mobility and the thermal behavior is used to analyze the stability of the supercooled liquid state of the compounds. The comparison between the pentitols shows that the crystallization processes are mainly dominated by the interfacial energy rather than by a competition between the thermodynamic driving force and the molecular mobility. [ABSTRACT FROM AUTHOR]