Fragility Index Research Articles

Enhancing the Resilience of Operational Microgrids Through a Two-Stage Scheduling Strategy Considering the Impact of Uncertainties

This article deals with the stochastic scheduling of a microgrid (MG) to balance the economical and resilience metrics. In the proposed model, the MG resilience indices are integrated into the economic criteria to ensure the resilience of MG operation alongside the main MG actors’ profit/loss. The MG fragility index, recovery efficiency index, MG voltage index, and lost load index are considered in the proposed planning model. Further, to make the results more realistic, the uncertainties associated with energy price and wind production, alongside with planning of energy storage systems and electric vehicles parking lots are considered. To achieve a better solution for the security-constraint operation of MG, AC network equations are included in the system modeling. Finally, a large-scale MG based on the IEEE-33 bus testbed is utilized to evaluate the effectiveness of the proposed stochastic scheduling program.

Trust shifting as a reaction to pandemic: Cross country analysis

Governance systems all over the world are coming under huge stress. Nowadays, two factors become crucial in the fight against the pandemic and its negative consequences: the state's ability to withstand stress in the economy and society; and civil support and approval of the governments' anti-crisis actions. This study aims to recognize the difference in stress response in different countries of the world. As a criterion for such a response, we consider the level of trust to governments in the context of the Covid-19 pandemic. The Fragile States Index was used as a measure of the state fragility, and the indices of trust were used as indicators of the people's reaction. The study showed that there is no correlation between 1) the trust in the government and the fragility of the state; 2) the support for government actions during the pandemic and the trust to the government before the pandemic. The clustering of countries by the set of indices of trust and fragility showed that the clusters' means support both the assumptions of a direct and an inverse relationship between trust and state resistance to stress. In response to quarantine measures, we see multidirectional trends in both stable and fragile states: trust can grow, fall, or remain unchanged. However, in stronger states, the tendency to an increase in trust is stronger, while in weaker states - to its fall, which confirms the thesis that in crisis the weak weakens and the strong strengthens. The results of the analyses provide arguments in favor of the following. The stability of the state does not guarantee the high trust of citizens and support for its actions during a crisis, and high trust is not a stable factor of high support for government actions. At the same time, it can be expected that the positive reaction of citizens to government measures (increased trust) will be more significant than disappointment (loss of trust).

How vulnerable is the fiscal posture in Turkey?

<abstract> <p>This study gauges the degree of fiscal vulnerability in Turkey by calculating the debt stabilising primary balance level and evaluates how this variable measures up against the actual primary balance levels for the 1978–2019 period. Based on this comparison, we build up a fiscal fragility index using the methodology described in <xref ref-type="bibr" rid="b15">Stoian (2012)</xref>. In addition, the Toda-Yamamoto causality test is carried out to detect the direction of causality among these two variables. The index-based analysis reveals that the fiscal performance of Turkey was chiefly satisfactory for the estimation period. Also, the Toda-Yamamoto causality test results imply a unidirectional causality from the required primary balance to real primary balance, suggesting that the government uses the primary balance to stabilise fiscal imbalances, which is an affirmative effort by the government to restore fiscal sustainability. Nevertheless, notwithstanding the implementation of corrective fiscal actions to preserve stability, the index value is steadily moving up in recent years, indicating a mounting fiscal vulnerability risk. Back-loading fiscal adjustments involving spending cuts, full-fledged tax reform, proper scrutiny of public expenses, etc., are among the prominent policy options available to the government to alter the ongoing unfavourable trend in the fiscal vulnerability index.</p> </abstract>

Measuring Fiscal Vulnerability and Fiscal Stress via Fiscal Fragility Index

Measuring Fiscal Vulnerability and Fiscal Stress via Fiscal Fragility Index

Configurational-based institutional analysis: Unbundling the multi-dimensional state fragility construct

To guide researchers interested in replicating our configurational approach to comparative institutional analysis, we report on a methodology that builds from existing state fragility indices to differentiate between types of state fragility in 189 countries across the world. We first present the steps we used to identify three constituent dimensions of state fragility. We then report how we configured these first-order institutional measures to build a large-N, fuzzy set qualitative set analysis (fs/QCA) of variation in the degree and type of informal economic sectors found across the world. Our discussion of the methodology shows that:•Configurational-based analysis requires unbundling aggregate measures into constituent dimensions as a first step to analyzing possible systemic interactions.•Configurational-based analysis recognizes sources of cross-national diversity that aggregated or single dimensional metrics are unable to fully capture.

Structural dependence of the molecular mobility in acetylated starch

In this study, the molecular mobility of acetylated starch (AS) with degree of substitution (DS) 1.5 and 3, representing partial and complete substitution of hydroxyl groups with acetyl groups, was investigated. The glass transition region and the onset of long-range cooperative molecular motions were examined using temperature-modulated-DSC (TMDSC). A potential analogy between the relaxation time of hole formation and the α-relaxation time was observed. The deviation in the temperature dependence of the α-relaxation time from the Arrhenius relationship, obtained with the fragility index, revealed differences according to DS. The cooperative rearranging region (CRR) characteristics differed according to DS and estimation method. Smaller size of the CRR for AS with DS 3 compared to AS with DS 1.5 suggest disruption of hydrogen bonds at high acetylation level. TMDSC experimental data at moderate temperature and predictions and SS-NMR results at ambient temperature, indicate different mobility of AS according to DS and temperature conditions.

Risk of foetal harm with letrozole use in fertility treatment: a systematic review and meta-analysis.

The aromatase inhibitor letrozole is increasingly recommended for ovulation induction, as it is more effective with fewer side-effects than other agents. But many clinicians are reluctant to use the drug for fertility treatment due to a strong-label warning against its use, which warns about congenital malformation risk to the foetus in women seeking pregnancy. The aim of this study was to determine the risks of congenital malformations and pregnancy loss with letrozole compared with clomiphene primarily, and with other fertility drugs and natural conception. A systematic review and meta-analysis using PRISMA harms guidelines. We searched MEDLINE, EMBASE and other sources from inception until January 2020, with the MeSH words for 'letrozole' and pregnancy OR foetal/neonatal outcome. We included studies reported on congenital malformations in foetuses born to mothers conceived after fertility treatment, with letrozole versus clomiphene, placebo, gonadotrophins, metformin, natural conception or other agents, from randomised trials, comparative cohort studies and non-comparative observational cohorts. Quality of the studies was assessed using Cochrane risk of bias tool and Newcastle Ottawa Scale. The McMaster tool was used to assess the quality of reported harm for foetal congenital malformations in the studies. We compared the absolute risk of events using risk difference measures and pooled the findings using a fixed-effect model. We evaluated the statistical heterogeneity using forest plots and the I2 statistic and funnel plot to assess publication bias. We assessed the strength of evidence for congenital malformation and pregnancy loss as per the GRADE recommendations and with the Fragility index. We included 46 studies (18 randomised trials; 21 comparative cohorts; 7 non-comparative cohorts). Overall 2.15% (101/4697; 95% CI 1.7 to 2.5) of babies conceived on letrozole for fertility treatment had congenital foetal malformations. We did not observe a significant increase in congenital malformations with letrozole versus clomiphene in the randomised trials (risk difference (RD) 0.01, 95% CI -0.02, 0.03; I2 = 0%; 14 studies) and found a significant reduction in the cohort studies (RD -0.02, 95% CI -0.04, -0.01; I2 = 0%, 11 studies). The fragility index was 44% (7/16) (either an increase in the intervention arm or a decrease in control arm was needed to alter the results). The risks of pregnancy loss were not increased with letrozole versus clomiphene in the 14 randomised trials (RD -0.01, 95% CI -0.06, 0.04; I2 = 0%), and the risks were reduced in the six cohort studies (RD -0.09, 95% CI -0.17, -0.00; I2 = 68%). The GRADE quality of evidence was low to moderate for congenital malformations and pregnancy loss. We did not find any increased congenital malformation risk with letrozole versus gonadotrophins, natural conception or natural cycle ART, but the number of studies was small. There is no evidence that letrozole increases the risk of congenital foetal malformation or pregnancy loss compared with clomiphene, natural conception or other fertility agents, to warrant warning against its use. Given its therapeutic benefits and lack of evidence of harm to the foetus, clinicians should consider letrozole as first-line agent for ovulation induction.

ViscNet: Neural network for predicting the fragility index and the temperature-dependency of viscosity

Viscosity is one of the most important properties of disordered matter. The temperature-dependence of viscosity is used to adjust process variables for glass-making, from melting to annealing. The aim of this work was to develop a physics-informed machine learning model capable of predicting the temperature-dependence of the viscosity of oxide liquids, inspired by the recent Neural Network (NN) reported by Tandia and co-authors. Instead of predicting the viscosity itself, the NN predicts the parameters of the MYEGA viscosity equation: the liquid’s fragility index, the glass transition temperature, and the asymptotic viscosity. With these parameters, viscosity can be computed at any temperature of interest, with the advantage of good extrapolation capabilities inherent to the MYEGA equation. The viscosity dataset was collected from the SciGlass database; only oxide liquids with enough data points in the “high” and “low” viscosity regions were selected, resulting in a final dataset with 17,584 data points containing 847 different liquids. About 600 features were engineered from the liquids’ chemical composition and 35 of these features were selected using a feature selection protocol. The hyperparameter (HP) tuning of the NN was performed in a set of experiments using both random search and Bayesian strategies, where a total of 700 HP sets were tested. The most successful HP sets were further tested using 10-fold cross-validation, and the one with the lowest average validation loss was selected as the best set. The final trained NN was tested with a test dataset of 85 liquids with different compositions than those used for training and validating the NN. The coefficient of determination (R2) for the test dataset’s prediction was 0.97. This work introduces three advantages: the model can predict viscosity as well as the liquids’ glass transition temperature and fragility index; the model is designed and trained with a focus on extrapolation; finally, the model is available as free and open-source software licensed under the GPL3.

Use of a 5-item modified Fragility Index for risk stratification in patients undergoing surgical management of proximal humerus fractures.

HypothesisWe hypothesized that the modified Fragility Index (mFI) would predict complications in patients older than 50 years who underwent operative intervention for a proximal humerus fracture.MethodsWe retrospectively reviewed the American College of Surgeons National Surgery Quality Improvement Program database, including patients older than 50 years who underwent open reduction and internal fixation of a proximal humerus fracture. A 5-item mFI score was then calculated for each patient. Postoperative complications, readmission and reoperation rates as well as length of stay (LOS) were recorded. Univariate as well as multivariable statistical analyses were performed, controlling for age, sex, body mass index, LOS, and operative time.ResultsWe identified 2,004 patients (median age, 66 years; interquartile range: 59-74), of which 76.2% were female. As mFI increased from 0 to 2 or greater, 30-day readmission rate increased from 2.8% to 6.7% (P-value = .005), rate of discharge to rehabilitation facility increased from 7.1% to 25.3% (P-value < .001), and rates of any complication increased from 6.5% to 13.9% (P-value < .001). Specifically, the rates of renal and hematologic complications increased significantly in patients with mFI of 2 or greater (P-value = .042 and P-value < .001, respectively). Compared with patients with mFI of 0, patients with mFI of 2 or greater were 2 times more likely to be readmitted within 30 days (odds ratio = 2.2, P-value .026). In addition, patients with mFI of 2 or greater had an increased odds of discharge to a rehabilitation center (odds ratio = 2.3, P-value < .001). However, increased fragility was not significantly associated with an increased odds of 30-day reoperation or any complication after controlling for demographic data, LOS, and operative time.ConclusionAn increasing level of fragility is predictive of readmission and discharge to a rehabilitation center after open reduction and internal fixation of proximal humerus fractures. Our data suggest that a simple fragility evaluation can help inform surgical decision-making and counseling in patients older than 50 years with proximal humerus fractures.

Effects of Aqueous Extract of Terminalia catappa L. on Membrane Stability of Sickle Cell Erythrocytes

Background: The effects of 800 mg% aqueous extract of T. catappa on membrane stability of human erythrocytes of HbSS genotype were investigated using in vitro studies.&#x0D; Aim: The aim of the study was to determine the membrane stabilizing potential of aqueous extract of T. catappa on sickle cell erythrocytes.&#x0D; Study Design: Laboratory Experimental Design was used in this study.&#x0D; Place and Duration: Department of Biochemistry, Imo State University, Owerri, Nigeria. The study was carried out between November, 2010 and May, 2011.&#x0D; Materials and Methods: Spectrophotometric method was employed in determining the osmotic fragility index of HbSS erythrocytes. The mean corpuscular fragility (MCF) of the control was 0.422 ± 0.80 g/100 ml, whereas that of the test sample was 0.36 ± 0.014 g/100 ml. The percentage stabilization for the HbSS erythrocytes, which was calculated using the MCF values, was 14.28%. The MCF values of the control and the test showed significant difference (p &lt; 0.05).&#x0D; Results: The result showed that aqueous extract of T. catappa exhibited an increasing capacity to stabilize HbSS erythrocytes membrane.&#x0D; Conclusion: The present study showed that aqueous extract of T. catappa L. exhibited membrane stability potential on sickle cell erythrocytes.

Statistical fragility of randomized clinical trials in shoulder arthroplasty.

The P value is a statistical tool used to assess the statistical significance of clinical trial outcomes in orthopedic surgery. However, the P value does not evaluate research quality or clinical significance. The Fragility Index (FI) is an alternative statistical method that can be used to assess the quality and significance of clinical research and is defined as the number of patients in a study intervention group necessary to convert an outcome from statistically significant to statistically insignificant or vice versa. The primary purpose of this study was to evaluate the statistical robustness of clinical trials regarding shoulder arthroplasty using the FI. The secondary goal was to identify trial characteristics associated greater statistical fragility. A systematic review of randomized clinical trials in shoulder arthroplasty was performed. The FI was calculated for all dichotomous, categorical study outcomes discussed in the identified studies. Descriptive statistics and the Pearson correlation coefficient were used to evaluate all studies and characterize associations between study variables. A total of 13 randomized controlled trials were identified and evaluated; these trials had a median sample size of 47 patients (mean, 54 patients; range, 26-102 patients) and a median of 7 patients (mean, 5.8 patients; range, 0-14 patients) lost to follow-up. The median FI was 6 (mean, 5; range, 1-11), a higher FI than what has been observed in other orthopedic subspecialties. However, the majority of outcomes (74.4%) had an FI that was less than the number of patients lost to follow-up, and most outcomes (89.7%) were statistically insignificant. Randomized controlled trials in shoulder arthroplasty have comparable statistical robustness to the literature in other orthopedic surgical subspecialties. We believe that the inclusion of the FI in future comparative studies in the shoulder arthroplasty literature will allow surgeons to better assess the statistical robustness of future research.

Mechanical and dynamic properties of V2O5-TeO2-P2O5 glasses

V2O5-TeO2-P2O5 (VTP) glasses are an important class of anode materials for potential applications in lithium-ion batteries (LIBs) owing to their unique structure, electronic conductivity and nano-crystal formation induced by the discharging/charging cycles. To enhance the cycling stability of the VTP glass anodes for LIBs, it is crucial to investigate their mechanical and dynamic properties. In this paper, we study the mechanical and dynamic properties of the VTP glass system by substituting P2O5 for TeO2. We found that the glass transition temperature (Tg), the hardness and the elastic moduli increase with the substitution, whereas the liquid fragility index (m) decreases. These trends could be attributed to the two factors. First, the substitution of P2O5 for TeO2 can lead to increased network connectivity. Second, the substitution makes the glass network more rigid due to the stronger P-O bond than Te-O and V-O bonds. These results are useful for designing the mechanically stable glass electrodes for LIBs.

Anomalously strong viscosity behavior in mixed oxy-sulfide Na4P2S7-xOx invert glasses

In this report, the first observations of the anomalously strong viscosity behavior in the melt quenched (MQ) invert mixed oxy-sulfide Na4P2S7-xOx, 0 ≤ x ≤ 5, (NaPSO) glass series. We find that these glasses even with 67 mole% modifier, Na2S, exhibit a calorimetric fragility index, mcal, as small as 29 compared to typical values of ~ 60 to 80 for alkali silicate glasses with > 50 mole% SiO2. We find that the calorimetric fragility of these glasses varies systematically with the extent of network forming bridging oxygens (BOs) in the glasses. The mcal values were converted to kinetic fragility (mvis) values and used with the measured Tgs to produce viscosity curves for the glasses using the Mauro-Yue-Ellison-Gupta-Allan (MYEGA) model. The viscosity of the glass with a minimum mcal value of x = 2.5 was then shown to exhibit a viscosity that was as strong as some alkali aluminosilicate glasses.In this report, the first observations have been made of anomalously strong viscosity behavior and correspondingly strong bulk glass formation and resistance to crystallization in a melt quenched (MQ) prepared series of invert, modifier content greater than the glass former content, mixed oxy-sulfide Na4P2S7-xOx, 0 ≤ x ≤ 5, (NaPSO) glasses. We find that these glasses even with 67 mole % modifier, Na2S, and only 33 mole% glass former P2S5-xOx, exhibit a calorimetric fragility index, mcal, as small as 29 compared to typical values of ~ 60 to 80 for alkali silicate glasses with > 50 mole% SiO2 and the theoretical minimum mcal of ~ 15. The mcal values were converted to kinetic viscosity fragility, mvis, values and used with the measured glass transition temperatures, Tgs, to produce viscosity curves for the glasses using the Mauro-Yue-Ellison-Gupta-Allan (MYEGA) model. The viscosity of the glass with a minimum mcal value of x = 2.5 was then shown to exhibit a viscosity that was as strong as, and for some compositions stronger than, the viscosity of alkali aluminosilicate glasses which have three dimensional network structures compared to the one dimensional chain structures observed in these MOS invert glasses. Consistent with these small values of fragility indices and therefore predicted higher viscosity above the glass transition temperature, Tg, in the supercooled liquid regime, these glasses are also particularly resistant to crystallization. For example, the x = 2.5 glass composition exhibits a crystallization temperature, TC, more than 150K above its Tg. We find that the calorimetric fragility of these glasses varies systematically with the extent of network forming bridging oxygens (BOs) in the glasses. The structural change caused by incrementally replacing sulfur with oxygen has been found to have consistent, large effects on the thermal properties.

The Statistical Fragility of Hamstring Versus Patellar Tendon Autografts for Anterior Cruciate Ligament Reconstruction: A Systematic Review of Comparative Studies

Background: Evidence-based medicine utilizes data to inform clinical decision making, despite the ability of a small number of outcome reversals to change statistical significance. P values are common measurements of statistical significance that possess inherent flaws. The inclusion of the fragility index (FI) and fragility quotient (FQ) may provide a clearer conveyance of statistical strength. Purpose/Hypothesis: The purpose was to examine the statistical stability of studies comparing hamstring tendon and bone–patellar tendon–bone autografts in primary single-bundle anterior cruciate ligament reconstruction with independent tunnel drilling. We hypothesized that the findings of these studies are vulnerable to a small number of outcome event reversals, often fewer than the number of patients lost to follow-up. Study Design: Systematic review. Methods: Comparative studies and randomized controlled trials (RCTs) published in 10 leading orthopaedic journals between 2000 and 2020 were analyzed. Statistical significance was defined as a P value ≤.05. FI for each outcome was determined by the number of event reversals necessary to alter significance. FQ was calculated by dividing the FI by the respective sample size. Results: Of the 1803 studies screened, 643 met initial search criteria, with 18 comparative studies ultimately included for analysis, 8 of which were RCTs. A total of 114 outcomes were examined. Overall, the mean (interquartile range) FI and FQ were 3.77 (2-4) and 0.040 (0.016-0.055), respectively. The FI was less than the number of patients lost to follow-up for 76.3% of outcomes. Conclusion: Studies examining graft choice for anterior cruciate ligament reconstruction may not be as statistically stable as previously thought. Comparative studies and RCTs are at substantial risk for statistical fragility, with few event reversals required to alter significance. The reversal of <4 outcome events in a treatment group can alter the statistical significance of a given result; this is commonly fewer than the number of patients lost to follow-up. Future comparative study analyses might consider including FI and FQ with P values in their statistical analysis.

Modified fragility index and surgical complexity score are able to predict postoperative morbidity and mortality after cytoreductive surgery for advanced ovarian cancer

ObjectiveThe aim of this study was to assess the impact of surgical complexity on postoperative complications and mortality, according to patient's frailty (mFI) following surgery for ovarian cancer. MethodsPatients undergoing cytoreductive surgery for ovarian cancer from 2008 to 2018 were identified from our database. A surgical complexity score from 1 to 3 was used to assess the extent of surgery (simple to complex, respectively). mFI with 11 variables, based on mapping the Canadian Study of Health and Aging Frailty Index to the NSQIP comorbidities was evaluated. Data were analyzed using Fisher exact test, independent sample t-test, and logistic regression. ResultsOf 263 patients identified, 33% reported at least one postoperative complication and 6% had severe complications. BMI ≥ 30 (p = 0.04) increased mFI (p = 0.04) and high-complexity surgery (p < 0.001) were independent predictors of severe complications (G3-G5). Patients with high frailty index score (mFI ≥ 3) who underwent intermediate or high-complexity surgery were at higher risk of severe complications ranging from 29.4% to 50. ConclusionsThe combined evaluation of mFI and surgical complexity expected may identify patients at higher risk for severe morbidity allowing to stratify patients who are less likely to tolerate a surgical extensive treatment.

On the crystallization kinetics of multicomponent nano-chalcogenide Se79-x Te15In6Pbx (x = 0, 1, 2, 4, 6, 8 and 10) alloys

Nanotechnology continuously rises due to its potential applications. To control nano-materials design and microstructure, it is very essential to understand nucleation and crystalline growth in these materials. In this research contribution, crystallization kinetics and thermal behaviour of nano-crystalline Se79-x Te15In6Pb x (x = 0, 1, 2, 4, 6, 8 and 10 at. wt%) chalcogenide alloys is analyzed through differential scanning calorimetry (DSC) process under non-isothermal conditions at four different heating rates; 5, 10, 15 and 20 °C min−1. The examined Se-Te-In-Pb nano-chalcogenide system is prepared through melt-quenching process. Characteristic temperatures namely glass transition temperature (T g), onset crystallization temperature (To), peak temperature of crystallization (T p) and melting temperature (T m) show dependence on heating rate and composition. The various kinetic parameters such as activation energy of glass transition (E g), activation energy of crystallization (E c), reduced glass transition temperature (T rg), Hruby number (K gl), thermal stability parameters (S and H’) and fragility index (F i) are analyzed for investigated Se-Te-In-Pb nano-crystalline system. Different empirical approaches are applied to determine the apparent glass transition activation energy (E g) and crystallization activation energy (E c).

DETERMINANTS OF SYSTEMATIC RISK IN HO CHI MINH CITY’ S REAL ESTATE COMPANIES

This paper aims to investigate factors affecting systematic risk in Ho Chi Minh City’s real estate companies for the period of 2010-2018. The research includes two stages: (i) Measuring systematic risk in Ho Chi Minh City's real estate companies following the approach of the Capital Asset Pricing Model (CAPM) of Sharpe [42] and Lintner [20]; (ii) Applying the panel data regression following Pooled OLS (POLS), Fixed Effect (FEM), Random Effect (REM) and General Method of Moments (GMM) models with two-step difference to identify factors affecting systematic risk in Ho Chi Minh City’s real estate companies. Findings from Ho Chi Minh City’s real estate companies indicate that financial leverage, interest rates, inflation are positively associated with the systematic risk, while systematic risk in the past, profitability, liquidity, real estate price index, land access index, economic growth, interest rates, banking sector fragility index and Government efficiency are negatively related to the systematic risk. This unique finding proposes significant implications for real estate executives, investors and policymakers.

Molecular mobility in amorphous biobased copolyesters obtained with 2,5- and 2,4-furandicarboxylate acid

Poly(ethylene 2,5-furandicarboxylate) (2,5-PEF) is one of the most credible biobased alternative to poly (ethylene terephthalate) (PET). The Henkel disproportionation reaction that leads to furandicarboxylic acid (FDCA) provides three position isomers: 2,5-FDCA (obtained with the highest yield), 2,4-FDCA (so far considered as a by-product), and 3,4-FDCA (traces). The copolymerization of the two main isomers of FDCA with a diol, e.g. ethylene glycol (EG), is an interesting approach to obtain a family of furan-based biopolymers with adjusted physical properties. This work investigates the molecular mobility of three copolymers obtained with EG and ratios of 2,5-FDCA and 2,4-FDCA ensuring the complete disruption of crystallization (90:10, 85:15 and 50:50 mol % of 2,5:2,4 FDCA), as compared to the homopolymers 2,5-PEF and 2,4-PEF. The molecular mobility was investigated by cross-comparing the results obtained by Modulated-Temperature Differential Scanning Calorimetry (MT-DSC), Dielectric Relaxation Spectroscopy (DRS) and Thermo-Stimulated Depolarization Currents (TSDC), with the aim of evaluating the local and segmental molecular mobilities, their activation energies, as well as the temperature dependence of the relaxation time and of the cooperatively rearranging regions at the glass transition. The furan ring in 2,5-FDCA (2,5-PEF) has a rotation axis that is less linear compared to the benzene ring in terephthalic acid (PET), with consequences on the ring-flipping mechanisms. 2,5-FDCA and 2,4-FDCA differ by the position of the carbonyl groups on the furan ring, which adds asymmetry to non-linearity. The incorporation of 2,4-FDCA-based units into a polymer backbone mainly constituted of 2,5-FDCA-based repeating units is responsible for longer relaxation times associated with the local β relaxation processes, no striking effects on the kinetic fragility index m, no obvious effects on cooperativity (a slightly increase in the cooperativity length is observed in the liquid state), no effects on the activation energy for the segmental α relaxation in the liquid state, and a decrease in the activation energy in the glassy state.

Molecular dynamics in the supercooled liquid and glassy states of bezafibrate and binary mixture of fenofibrate

Two solubility limited pharmaceuticals bezafibrate and fenofibrate, belonging to BCS class II drugs, were compared, by investigating molecular dynamics of the former and compared with the neat and as a probe in an apolar host polystyrene of mole. wt. 800 (PS800) of the latter by broadband dielectric spectroscopy (BDS), other supporting thermal and spectroscopic experimental means and density functional theory (DFT) calculations. The BDS experiments from frozen glassy state to vibrant molten state of the title drugs were done to explore the role of parameters describing their complex molecular dynamics and the stabiliy of amorphous phase, such as glass transition temperature (Tg), temperature dependence of α-relaxation times (τα), width of structural dispersion and its role on the occurrence of Johari-Goldstein (JG) β-relaxation, fragility index (m) and apparent activation energy of secondary processes. Realizing that most of the pharmaceuticals have narrow α-dispersion which limits the visibility of JG β-relaxation as a separate process in the dielectric window, to resolve the conundrum, we have further explored the amorphous dynamics of fenofibrate as a probein an apolar host polystyrene of molecular weight 800 (PS800) having higher Tg than the polar probe. The Tg of bezafibrate and PS800-fenofibrate mixture were determined to be 298 K and 275 K respectively, whereas the fractional exponent of Kohlrausch–Williams–Watts function βKWW of bezafibrate was determined to be 0.68 which is closer to that of fenofibrate, whereas that of PS800-fenofibrate mixture was found to be much broader with a value of 0.39, all in the vicinity of Tg. Even though βKWW decreased in binary mixture of fenofibrate when compared to its pure form due to concentration fluctuations and other aspects, but cold crystallization tendency was absent and Tg is elevated than that of fenofibrate. Due to higher Tg than that of fenofibrate, amorphous bezafibrate is more stable than fenofibrate. Finally, using quantum computational calculations using DFT, the relevant flexible parts of the two drug molecules, whose motions manifests the secondary γ-relaxation was identified by calculating potential energy barriers and dipole moments on relaxed dihedral angle scans, as no experimental technique is available for this purpose.

Social Isolation and Psychological Distress During the COVID-19 Pandemic: A Cross-National Analysis.

Background and ObjectivesThe coronavirus disease 2019 (COVID-19) pandemic resulted in social isolation globally, creating heightened levels of stress and anxiety. This study investigates the link between social isolation and mental well-being in later life, and how it varies across countries.Research Design and MethodsWe draw on a subset of older adults from Global Behaviors and Perceptions in the COVID-19 pandemic, a unique global online survey of 13,660 participants from 62 countries. We use mixed-effects models to analyze the data.ResultsSocial isolation (distancing) significantly predicts poor mental health operationalized as coronavirus-induced distress (p < 0.01). At the aggregate level, average distress varies positively across countries with higher numbers of coronavirus-related deaths (p < 0.10) and more fragile state capacity (p < 0.05), while varying negatively across those with more stringent anti-coronavirus policies (p < 0.05). Finally, we report several cross-level interactions between social isolation and the total number of deaths (p = 0.025), policy stringency (p =0.065), state fragility (p = 0.061), and globalization index (p = 0.071).Discussion and ImplicationsOur study shows that a proper understanding of the impact of COVID-19 on the mental well-being of older adults should consider the moderating role of national context.