bluuebunny/crossref_metadata_2025 huggingface dataset:
Computation of the Binding Energies between Human ACE2 and Spike RBDs of the Original Strain, Delta and Omicron Variants of the SARS‐CoV‐2: A DFT Simulation Approach
Authors: Yamacli Serhan , Avci Mutlu
Published: September 2022

The receptor binding domain (RBD) of SARS‐CoV‐2 binds to human ACE2 leading to infection. In this study, the complexes that are formed by the attachment of the SARS‐CoV‐2 spike RBDs of the original strain, delta and omicron variants to the human ACE2 are investigated via density functional theory (DFT) simulations to obtain binding energies. The DFT computations are performed without fragmenting the interfaces to involve longer‐range interactions for improved accuracy, which is one of the primary features of the approach used in this study. Basis set superposition error corrections and van der Waals dispersions are also included in the DFT simulations. The binding energies of the SARS‐CoV‐2 spike RBDs of the original strain, delta and omicron variants to the human ACE2 are computed as −4.76, −6.68, and −11.77 eV, respectively. These binding energy values indicate that the binding of the omicron variant to the ACE2 is much more favorable than the binding of the original strain and the delta variant, which constitute a molecular reason for the takeover of the omicron variant. The binding energies and the decomposition of these energies found in this study are expected to aid in the development of neutralizing agents.
Boosting Battery Safety by Mitigating Thermal‐Induced Crosstalk with a Bi‐Continuous Separator
Authors: Song Youzhi , Wang Li , Cui Hao , Liang Hongmei , Hu Qiao , Ren Dongsheng , Yang Yang , Zhang Hao , Xu Hong , He Xiangming
Published: September 2022

Lithium‐ion batteries are taking center stage in the environmental revolution through the ever‐growing adoption of electric vehicles. However, safety issues derived from battery thermal runaway remain a prominent challenge. In this work, a bi‐continuous separator (Bi‐Sep) via micro‐gravure and phase inversion techniques is developed. The proposed nonshrinkage separator exhibits a nanoporous morphology and a super‐stretchable property, thus effectively blocking both internal short circuits and chemical crosstalk between electrodes at thermal abusive temperatures. Besides its considerable performance at normal conditions, the LiNi0.6Co0.2Mn0.2O2/graphite pouch cell assembled with the Bi‐Sep separator presents superior sustainability at an elevated temperature of 60 °C. Moreover, the cell using this Bi‐Sep separator achieves an extremely high level of survivability under thermal abusive conditions. This work concludes that engineering the porous structure and thermomechanical properties of a separator, rather than simply improving its heat‐resistance, is of significant importance for the development of safe batteries.
Associations between different heart rate variability ratios and cardiometabolic risk factors in young adults
Authors: Plaza‐Florido Abel , Sacha Jerzy , Alcantara Juan M. A.
Published: September 2022

Aims

To study the association of two different heart rate variability (HRV) ratios with cardiovascular disease (CVD) risk factors in young adults.

Method

A total of 132 participants (89 women) were included in this cross‐sectional study. We assessed their HRV and computed the low frequency‐to‐high frequency ratio (LF/HF) and, from the Poincaré plot, the ratio of the inverse of the longitudinal (SD2) to the transversal (SD1) axes ([1000/SD2]/SD1; sympathetic: parasympathetic [S:PS] ratio). From blood samples, we determined total cholesterol, high‐density (HDL‐C) and low‐density lipoprotein‐cholesterol, triglycerides, glucose, insulin, and the homeostatic model assessment of insulin resistance (HOMA) index. Multiple linear regression models were adjusted for age.

Results

Both, the LF/HF and the S:PS ratios, were positively associated with glucose metabolism markers (glucose, insulin, HOMA index), and negatively associated with HDL‐C in women but not in men.

Conclusion

We showed that the LF/HF and the S:PS are associated similarly with CVD risk factors in young women.
Association between social determinants of health and olfactory dysfunction in older adults: A population‐based analysis
Authors: Stein Eli , Chern Alexander , Chen Honglei , Shiroma Eric J. , Devanand D. P. , Gudis David A. , Overdevest Jonathan B.
Published: September 2022

Background

Social determinants of health (SDoH) are environmental conditions that influence health outcomes. As olfactory dysfunction (OD) in older individuals is associated with increased morbidity and mortality, we sought to investigate the impact of specific SDoH on olfactory function.

Methods

A cross‐sectional analysis of the Health, Aging and Body Composition Study, a US population‐based epidemiologic cohort study, was performed. Olfactory function was assessed utilizing both a self‐report and a psychophysical olfactory test (CC‐SIT test). Multivariable logistic regressions were performed to examine associations between specific SDoH with self‐reported anosmia (sOD) and objective anosmia (oOD) as assessed by psychophysical testing. Differences in sensitivity and specificity were evaluated with sample tests for equality of proportions.

Results

Of 2219 participants, 13% had oOD and 18% had objective hyposmia; only 10% had sOD. Individuals identifying as Black race had higher odds of oOD (odds ratio [OR]:1.41, 95% confidence interval [CI]:1.02‐1.95), while females and those reporting family incomes ≥$50,000 had lower odds of oOD (OR: 0.46, CI:0.34‐0.62; OR:0.52, CI:0.29‐0.93), adjusting for covariates. No specific SDoH was significantly associated with sOD. The sensitivity and specificity of sOD for oOD was 23.1% and 92.0%, respectively. sOD had greater sensitivity in females than males (30.8% vs. 18.8%, p = 0.030), while specificity varied significantly depending on family income (range: 90.0%‐94.8%, p = 0.033).

Conclusions

Utilizing a large population‐based study, we find disparities in the prevalence and self‐recognition of OD among individuals of different gender, race, and income levels. Further effort is needed to evaluate factors propagating these disparities and to raise awareness of OD across all patient populations.
Effects of cocoa extract and a multivitamin on cognitive function: A randomized clinical trial
Authors: Baker Laura D. , Manson Joann E. , Rapp Stephen R. , Sesso Howard D. , Gaussoin Sarah A. , Shumaker Sally A. , Espeland Mark A.
Published: September 2022

Introduction

Dietary supplements are touted for cognitive protection, but supporting evidence is mixed. COSMOS‐Mind tested whether daily administration of cocoa extract (containing 500 mg/day flavanols) versus placebo and a commercial multivitamin‐mineral (MVM) versus placebo improved cognition in older women and men.

Methods

COSMOS‐Mind, a large randomized two‐by‐two factorial 3‐year trial, assessed cognition by telephone at baseline and annually. The primary outcome was a global cognition composite formed from mean standardized (z) scores (relative to baseline) from individual tests, including the Telephone Interview of Cognitive Status, Word List and Story Recall, Oral Trail‐Making, Verbal Fluency, Number Span, and Digit Ordering. Using intention‐to‐treat, the primary endpoint was change in this composite with 3 years of cocoa extract use. The pre‐specified secondary endpoint was change in the composite with 3 years of MVM supplementation. Treatment effects were also examined for executive function and memory composite scores, and in pre‐specified subgroups at higher risk for cognitive decline.

Results

A total of 2262 participants were enrolled (mean age = 73y; 60% women; 89% non‐Hispanic White), and 92% completed the baseline and at least one annual assessment. Cocoa extract had no effect on global cognition (mean z‐score = 0.03, 95% CI: ‐0.02 to 0.08; P = .28). Daily MVM supplementation, relative to placebo, resulted in a statistically significant benefit on global cognition (mean z = 0.07, 95% CI 0.02 to 0.12; P = .007), and this effect was most pronounced in participants with a history of cardiovascular disease (no history: 0.06, 95% CI 0.01 to 0.11; history: 0.14, 95% CI ‐0.02 to 0.31; interaction, nominal P = .01). Multivitamin‐mineral benefits were also observed for memory and executive function. The cocoa extract by MVM group interaction was not significant for any of the cognitive composites.

Discussion

Cocoa extract did not benefit cognition. However, COSMOS‐Mind provides the first evidence from a large, long‐term, pragmatic trial to support the potential efficacy of a MVM to improve cognition in older adults. Additional work is needed to confirm these findings in a more diverse cohort and to identify mechanisms to account for MVM effects.

Highlights

COSMOS‐Mind was a large simple pragmatic randomized clinical trial in older adults conducted by mail and telephone.

The trial used a two‐by‐two factorial design to assess treatment effects of two different interventions within a single large study.

We found no cognitive benefit of daily cocoa extract administration (containing 500 mg flavanols) for 3 years.

Daily multivitamin‐mineral (MVM) supplementation for 3 years improved global cognition, episodic memory, and executive function in older adults.

The MVM benefit appeared to be greater for adults with cardiovascular disease.
Differences between blood and cerebrospinal fluid glial fibrillary Acidic protein levels: The effect of sample stability
Authors: Simrén Joel , Weninger Haley , Brum Wagner S. , Khalil Shilla , Benedet Andréa L. , Blennow Kaj , Zetterberg Henrik , Ashton Nicholas J.
Published: September 2022

Introduction

Recent evidence has shown that the marker of reactive astrogliosis, glial fibrillary acidic protein (GFAP), has a stronger relationship with cerebral amyloid beta (Aβ) pathology in blood than in cerebrospinal fluid (CSF). This study investigates if pre‐analytical treatment of blood and CSF contribute to these unexpected findings.

Methods

Paired CSF and serum samples from 49 individuals (Aβ‐negative = 28; Aβ‐positive = 21) underwent a series of seven freeze‐thaw cycles (FTCs). All samples were analyzed for GFAP and neurofilament light (NfL) using single molecule array technology including a fresh unfrozen sample from each patient.

Results

FTC significantly affected CSF GFAP concentration (−188.12 pg/ml per FTC) but not serum GFAP. In the same samples, NfL remained stable. Serum GFAP had a higher discrimination of Aβ burden than CSF GFAP, irrespective of FTC, which also included unfrozen samples.

Discussion

This study demonstrates large stability differences of GFAP in CSF and serum. However, this disparity does not seem to fully explain the stronger association of serum GFAP with Aβ pathology. Further work should investigate mechanisms of GFAP release into the bloodstream under pathological conditions.
An environmental DNA approach to informing restoration of the functionally extinct oyster, Ostrea angasi
Authors: Coutts Alexander , O'Brien Allyson , Weeks Andrew R. , Swearer Stephen E. , van Rooyen Anthony , Branigan Simon , Morris Rebecca L.
Published: September 2022

The success of oyster reef restoration can be enhanced by data on the distribution of remnant populations to inform the selection of suitable restoration locations. A quantitative polymerase chain reaction‐based environmental DNA (eDNA) assay was designed to provide distribution data for the oyster, Ostrea angasi, whose reefs are functionally extinct in Port Phillip Bay, Australia.

Ostrea angasi eDNA accumulation and decay was measured in aquaria containing oysters in low and high densities, prior to testing the efficacy of the eDNA approach for detection of oysters at 15 field sites. Ostrea angasi eDNA accumulated significantly faster in aquaria where more individuals were present, while eDNA became undetectable 2–6 days after oysters were removed in low‐density treatments.

The eDNA samples were successful at detecting O. angasi in the field when taken in close proximity of an oyster population. Increasing the sample number and volume could maximize oyster detection, demonstrating the potential of eDNA to identify suitable sites for the restoration of functionally extinct marine ecosystems.
Critical Role of LMCD1 in Promoting Profibrotic Characteristics of Lung Myofibroblasts in Experimental and Scleroderma‐Associated Lung Fibrosis
Authors: Bogatkevich Galina S. , Atanelishvili Ilia , Bogatkevich Andrew M. , Silver Richard M.
Published: September 2022

Objective

Interstitial lung disease (ILD) is a serious complication and leading cause of mortality in patients with systemic sclerosis (SSc). In this study, we explored the role of LIM and cysteine‐rich domains protein 1 (LMCD1) as a novel factor in the pathogenesis of SSc‐related ILD (SSc‐ILD).

Methods

The expression and effects of LMCD1 were studied in lung tissue samples and fibroblasts from SSc‐ILD patients and control subjects as well as in lung tissue samples from animal models.

Results

LMCD1 was consistently elevated in lung tissue samples and in fibroblasts isolated from SSc‐ILD patients as compared to controls. Additionally, LMCD1 was found to be highly expressed in the lung in the fibroblast‐specific protein (FSP)–driven, constitutively active transforming growth factor β receptor type I (TGFβR1) transgenic mouse model of ILD and the bleomycin‐induced mouse model of ILD. In lung fibroblasts from SSc‐ILD patients, LMCD1 is an essential factor for the TGFβ‐induced generation of type I collagen, fibronectin, and α‐smooth muscle actin (α‐SMA). Depletion of LMCD1 by small interfering RNA reduced the expression of extracellular matrix proteins and lowered transcriptional activity and expression of α‐SMA, as well as decreased the proliferation and contractile activity of SSc‐ILD lung fibroblasts. In dense fibrotic areas of affected lung tissue, lung LMCD1 colocalized with α‐SMA. In cultured scleroderma lung fibroblasts, LMCD1 colocalized and interacted with serum response factor which mediates LMCD1‐induced contractile activity of lung fibroblasts.

Conclusion

Our study identifies LMCD1 as a profibrotic molecule contributing to the activation of myofibroblasts and the persistent fibroproliferation observed in SSc‐ILD. Thus, LMCD1 may be a potential novel therapeutic target for patients with SSc‐ILD.
Preparation of a novel group of chemiluminescent N‐substituted acridinium esters
Authors: Smith Keith , Mu Xiaojing , Li Zhaoqiang , Woodhead J. Stuart , El‐Hiti Gamal A.
Published: September 2022

Several novel N‐substituted acridinium esters 7–16 containing a 10‐methyl, 10‐dodecyl, or 10‐(ω‐[succinimidyloxycarbonyl]alkyl) group have been synthesized and their chemiluminescent properties have been tested. Their chemiluminescent efficiencies and hydrolytic stabilities have been found to be affected by the characteristics of the group on the nitrogen atom. Dibromo‐substituted leaving groups slightly accelerate the chemiluminescence process.
Simultaneous determination of serum tryptophan metabolites in an older Chinese population
Authors: Wang Sheng , Feng Rui , Chen Guan‐Jun , Sang Yan‐Ru , Kong Li , Yu Shui‐Xin , Tao Fang‐Biao , Liu Kai‐Yong
Published: September 2022

Tryptophan (TRP) and its metabolites exhibit significant biological effects and are strongly associated with age‐related disease and mortality. However, reports on quantitatively analyzing these metabolites in older individuals are not available. We used ultra‐high‐performance liquid chromatography–tandem mass spectrometry to optimize and validate a method for isotope dilution analysis of TRP metabolites in older individuals. The targeted analytes are TRP, serotonin or 5‐hydroxytryptamine, kynurenine, kynurenic acid, xanthurenic acid, indole‐3‐acetic acid, indole‐3‐propionic acid, and tryptamine. The serum sample was purified using solid‐phase extraction and was separated on a Waters HSS T3 column (100 mm × 2.1 mm, 1.8 μm). The analytes were detected in the multiple reaction monitoring mode under positive ionization. TRP was confirmed and measured after being diluted 100 times. This method exhibited satisfactory linearity (r > 0.99). The intrabatch and interbatch accuracies (85.7–114%) and precisions (<15%) were acceptable. The standard‐normalized matrix effects ranged from 51.6 to 145%. This method was successfully applied to a cohort of 1021 older Chinese individuals, and this study may enable further understanding of the metabolic phenotypes associated with TRP in other populations.
How academic performance influences social integration: The moderation effect of cultural distance among Chinese cross‐borderers
Authors: Jieyi Hu , Kiu Cheung Chau , Baojian Xie
Published: September 2022

Background

Internal migration or cross‐border migration differs from traditional migration. The influence of academic performance on social integration among migration or cross‐border student groups has drawn attention.

Method

A survey collected data from cross‐border students in Mainland China.

The sample included 616 university students (bachelor's, master's, and doctoral students) coming from Hong Kong studying in Guangzhou, Guangdong Province.

Results

The moderating effect of cultural distance in the relationship between academic performance and social integration was significantly negative (β = –0.081, p < 0.05). The effect of academic performance on social integration was significantly positive (β = .104, p < .05). Length of time studying in the Mainland, social status, entrance exam score (which might affect the current academic performance), and acquiescence are as the control variable in examining the role of cultural distance in the effect of academic performance on social integration. This result embodies the functionalist theory.

Conclusion

The host society is the structural whole requiring the function of social integration, whereas education is the structural component fulfilling the function. When cultural distance is large, the function of education for social integration decreases. The practical implication for enhancing social integration is relieving or bridging the distance.
Intracortical myelin in individuals with alcohol use disorder: An initial proof‐of‐concept study
Authors: Morris Vanessa , Bock Nicholas , Minuzzi Luciano , MacKillop James , Amlung Michael
Published: September 2022

Introduction

Disruption of cortical gray matter and white matter tracts are well‐established markers of alcohol use disorder (AUD), but less is known about whether similar differences are present in intracortical myelin (ICM, i.e., highly myelinated gray matter in deeper cortical layers). The goal of this study was to provide initial proof‐of‐concept for using an optimized structural magnetic resonance imaging (MRI) sequence to detect differences in ICM in individuals with AUD compared to control participants reporting drinking within recommended guidelines.

Methods

This study used an optimized 3T MRI sequence for high intracortical contrast to examine ICM‐related MRI signal in 30 individuals with AUD and 33 healthy social drinkers. Surface‐based analytic techniques were used to quantify ICM‐related MRI signal in 20 bilateral a priori regions of interest based on prior cortical thickness studies, and exploratory vertex‐wise analyses were examined using Cohen's d effect size.

Results

The global distribution of ICM‐related signal was largely comparable between groups. Region of interest analysis indicated that AUD group exhibited greater ICM‐related MRI signal in precuneus, ventromedial prefrontal cortex, posterior cingulate, middle anterior cingulate, middle/posterior insula, and dorsolateral prefrontal cortex (Cohen's ds = 0.50–0.75). Four regions (right precuneus, ventromedial prefrontal cortex, posterior cingulate and left dorsolateral prefrontal cortex) remained significant (p < .05) after covarying for smoking status.

Conclusion

These findings provide initial evidence of ICM differences in a moderately sized sample of individuals with AUD compared to controls, although the inflation of type 1 error rate necessitates caution in drawing conclusions. Robustly establishing these differences in larger samples is necessary. The cross‐sectional design cannot address whether the observed differences predate AUD or are consequences of heavy alcohol consumption.
Heterogeneously Catalyzed Carboxylic Acid Hydrogenation to Alcohols
Authors: Karam Leila , Neumann Constanze N.
Published: September 2022

This critical review discusses the synthesis of alcohols via hydrogenation of carboxylic acids promoted by heterogeneous metal catalysis. The introductory chapter rationalizes the comparative reactivity of carboxylic acid derivatives, which is proceeded by a description of different mechanisms for carboxylic acid hydrogenation. Reaction pathways are discussed that give rise to undesired side products, before comparing the reactivity of different classes of carboxylic acid substrates with a focus on biomass‐derived carboxylic acids. The final portion of the review aims to guide researchers in the selection of appropriate reaction conditions, such as the choice of solvent, transition metal, and catalyst support.
Material Ductility and Buckling Behaviour of Eurocode‐compliant Cold‐formed Steel Hollow Columns
Authors: Landolfo Raffaele
Published: September 2022

Square and rectangular cold‐formed hollow sections are generally produced by either direct forming or indirect forming. These methods allow manufacturing nominally similar geometries of the cross‐sections, but leading to some different mechanical characteristics. The present paper addresses cold‐formed structural hollow sections produced by indirect forming that are characterized by the greater residual stresses, focusing on (i) the ductility of the cold‐formed material in the corners and flat parts of the section; (ii) the reliability of the buckling curves given by EN1993‐1‐1 for this type of columns. The reliability assessment is performed using first order reliability method on a detailed and validated numerical model developed in OpenSees. The results show that the current curve “c” in EN1993‐1‐1 underestimates the buckling capacity of stocky members.
Ductility and Strength of High‐strength Bolted Connections for High‐strength Constructional Steels
Authors: Li Guo‐Qiang , Lyu Yi‐Fan , Wang Yan‐Bo
Published: September 2022

This paper conducts an investigation on ductility and strength of high strength bolted connections for high strength constructional steels. Ductility and strength of different bolted connection types are comprehensively studied and compared. It is found that reduction in material elongation capacity for high strength steels has negligible effect on the ductility of bolted connections. When the net cross‐section failure is prevented, similar ductility is found for the bearing‐type bolted connection with different number of bolts. In addition, the misalignment of bolt hole will not introduce negative effect on ductility and strength of the connection. The load‐displacement curve for the connection with misaligned bolt hole will coincide with the connection without misaligned bolt hole. It is concluded that similar ductility of bearing‐type connection is maintained with increasing steel grade while strength of multi‐bolt connection in high strength steel can still be calculated by summation of each individual bolt.
Distortion – Induced Fatigue Failure at Main Girders of a Railway Bridge – Strain Measurements in Service and Analyses Based on Fracture Mechanics
Authors: Derler Christoph , Unterweger Harald
Published: September 2022

At the main girders of a three span continuous plate girder railway bridge, built in the 1970s, through‐thickness cracks were detected in the web, at the location of the transverse stiffener to main girder connections. Based on former Austrian standards for steelwork, the transverse stiffeners are not welded to the main girder flanges in order to increase their fatigue resistance. Instead, fitting pieces between the stiffeners and the bottom flanges were used.

Within the paper the geometry and the location of the cracks are presented. For the global stresses, due to moments and shear forces, numerical simulations of the train passages were done. Based on these global stresses only, the fatigue damage for the main girders was evaluated at each position of a transverse stiffener connection. Since there was no significant agreement between the distribution of the global fatigue damage along the main girder and the crack positions, the out‐of‐plane distortion in the web gap region was expected as the obvious cause for the cracks.

To verify the complex local stress field in the web gap region (interaction of global and local stresses), comprehensive strain measurements were done during service. The relevant results, including passages of slow and fast individual locomotives, passenger and freight trains, are presented and compared.

Finally, based on the measured stress range spectra the further crack growth behavior was analyzed and the residual fatigue life was predicted using a linear elastic fracture mechanics (LEFM) approach where also the mixed‐mode conditions at the crack tips were considered.
Geometrical Digital Twinning of a Tapered, Horizontally Curved Composite Box Girder Bridge
Authors: Chacón Rolando , Ramonell Carlos , Puig‐Polo Càrol , Mirambell Enrique
Published: September 2022

A composite bridge located in the Metropolitan Area of Barcelona represents one of the sites for demonstrating the capabilities of digital twins on maintenance of built assets. Digital twins can be deemed to as digital living replica of the physical one that provides real time information throughout adequate connectivity (sensors, images, remote sensing) and provides automated visualization of the asset for decision‐making purposes (performance indicators that are assessed regularly). This demonstrator is an 846 meters long composite bridge with plates and a concrete slab. The plates are tapered along a portion of its length. The bridge is horizontally curved with a bifurcation at its end. One of the challenges in this demonstrator is to reproduce realistically the “as built” shape of the plates using a terrestrial laser scanner for simulation purposes. The outcome of this specific side of the digital twinning (other sides also include many sensor‐ and image‐based methods) is of great interest for maintenance managers. Understanding the real configuration of the asset represents an accurate starting point for subsequent modelling.
Moment Resistance Analysis of Thin‐walled Stiffened Sections by the Alternative Method of EN1993: Part:1‐3
Authors: Carvalho Carlos , Prola Luís
Published: September 2022

Thin‐walled sections distortional buckling phenomena is treated in EN1993 part:1‐3 (EC3‐1‐3) through the calculation of reduced thickness of stiffeners group, mainly by the application of the simplified method presented in this specification which comes with a limitation of applicability to non‐standard sections or with multiple stiffeners that can result in over conservative or insecure results.

With the objective of facilitating de study/utilization of such kind of sections by designers, maintaining a safe set of results and without the overwhelming amount of calculations, the alternative method in clause 5.5.1(7) is used, applied only to the distortional analysis and correspondent effective thickness of stiffeners

This alternative method allows the use of Linear Buckling Analysis (LBA), which, in this paper, are obtained through the Generalized Beam Theory (GBT) by the GBTUL computer application that applies this theory in the identification of distortional modes and buckling critical loads calculation. The results are then incorporated in EC3‐1‐3 algorithm as defined in clause 5.5.1(7). For the application of this alternative method the LBA results are integrated with EC3‐1‐3 using the Class4Section application, updated for this paper, which uses the critical buckling loads for the calculation of the critical stress of stiffeners group. This more generic approach by the alternative method is easily implemented in computational environment.

Following previous work by the authors, the section moment capacity is analyzed in this paper by applying this alternative method and comparing it with available experimental results for selected thin‐walled sections mainly used in flexural problems, namely Sigma and Omega section types, as well as the most commonly known C and Z sections, but with multiple stiffeners.
Experimental and Numerical Studies of Bolted Lap Joints at Elevated Temperature
Authors: Der Batuhan , Wald František
Published: September 2022

This paper presents an experimental and numerical studies of bolted double lap joints at ambient and elevated temperatures. Nine experiments conducted at the Czech Technical University in Prague investigated the mechanical behavior of bolted lap joints at 20°, 400° and 600°C. The design strengths of steel joints subjected to tensile forces are predicted using European standards for steel structures. The general finite element (FE) software ABAQUS/Standard 6.14 is employed for the numerical analysis. In this work, different numerical models are prepared to investigate a modeling technique of the bolted joints The plates are modelled using solid and shell elements and the bolt is represented by solid element and a combination of beam elements coupled to surfaces. All the studied models consider the contact behavior. The numerical models are validated using data from experimental tests. The analytical model serves for verification of numerical models. The validation and verification approved the numerical models. Consequently, the modeling techniques used in this research can give reasonable results to predict the resistance bolted joints at elevated temperature and can be used to predict the resistance in design level.
Ductile Fracture Simulation of Stainless Steel Coupons Under Monotonic Tensile Forces
Authors: González‐de‐León Isabel , Arrayago Itsaso , Nastri Elide , Real Esther
Published: September 2022

Stainless steel alloys exhibit a nonlinear stress‐strain behaviour which can be precisely described by the Ramberg‐Osgood material model up to the ultimate stress. However, there is no consensus on the ductile fracture model under monotonic loading, which affects the post‐necking stress‐strain behaviour, to be adopted for stainless steels, even though the fracture model may have clear applications in structural design, such as in predicting joint failure in direct design approaches. This study presents the calibration of the fracture parameters for two of the most common ductile fracture models: the modified critical stress model and the Lee and Wierzbicki model. The calibrations are based on experimental results from tensile coupons tests on austenitic, ferritic and duplex stainless steel, extracted from cold‐formed tubes and sheet material, and on advanced finite element simulations. The calibrated values show a low dispersion for each of the analysed materials, indicating that the fracture parameters are an inherent property of the material, and which have been found to be slightly higher for the more ductile alloys. Average values of the fracture parameters for different stainless steels are also preliminarily proposed for their direct application in finite element simulations.
Microstructure, Mechanical Properties and Cross‐sectional Behaviour of Additively Manufactured Stainless Steel Cylindrical Shells
Authors: Zhang Ruizhi , Amraei Mohsen , Piili Heidi , Gardner Leroy
Published: September 2022

Powder bed fusion (PBF) is an additive manufacturing method that enables complex metallic components to be manufactured with high precision. The microstructure, mechanical properties and cross‐sectional behaviour of PBF additively manufactured stainless steel circular hollow sections are investigated through experiments in this paper, with a view to applications in construction. The experimental programme included tensile coupon tests, microstructural characterisation, initial geometric imperfection measurements and compression tests on PBF 316L stainless steel cylindrical shells with large diameter‐to‐thickness (D/t) ratios. Advanced measurement methods – 3D laser scanning and digital image correlation, were employed to measure the specimen geometries prior to testing and deformation fields during testing, respectively. The possible anisotropy in mechanical properties was examined through tensile coupon tests and correlated with the underlying microstructural and textural features. Compression tests were performed to investigate the resistance against local buckling of thin‐walled cylindrical shells produced by PBF. All cylindrical shells buckled below their yield loads with a chequerboard failure mode and revealed the anticipated trend of reducing capacity relative to the yield load with increasing local slenderness, reflecting the increasing susceptibility to local buckling.
Buckling Analysis of Cylindrical Shells using Stochastic Finite Element Method with Random Geometric Imperfections
Authors: Li Zheng , Pasternak Hartmut , Geißler Karsten
Published: September 2022

Thin‐walled cylindrical shells often exhibit buckling failure and the experimental buckling load is usually lower than calculation results from classical theory and simulation without geometrical imperfection. Besides, test results with carefully conducted similar specimens still have substantial scatter due to imperfection sensitivity. The nonlinear analysis with FEM can obtain a high‐precision result comparing the experiment. However, this is almost impossible in practical engineering. The initial geometric imperfections of cylindrical shells are complex and random properties. Theoretically, these geometric imperfections can be described using a random field or a Fourier series representation. After that a random sample of the buckling bearing capacity of the cylindrical shell can be obtained using the stochastic finite element method within the subsequent analysis. This paper presents the investigation of buckling analysis of cylindrical shells under axial compression considering the randomness of initial geometric imperfections, and the stochastic FEM is employed to calculate the statistical sample of the shell‐buckling load based on a series of random fields and Fourier series representation of geometric imperfections.
Numerical Study of Non‐linear Buckling Analysis for Steel and Partial Concrete Encased Composite Columns
Authors: Zogu Pëllumb , Schäfer Markus
Published: September 2022

Buckling is a complex phenomenon, influenced by the non‐linear material properties, as yielding of steel, cracking of concrete as well as, slenderness, geometrical imperfection and residual stresses. The design codes provide essential rules for mechanical resistance, stability and safety aspects. However, the current Eurocodes essentially stipulates engineering models that can easily be transferred to classical structural analysis, but often do not guide sufficiently the application and evaluation of advanced numerical analysis.

The present study investigates the buckling analysis of steel and partial encased composite columns. Different definitions for geometrical imperfections and residual stresses are considered. The geometrical imperfections are taken into account in accordance with prEN1993‐1‐14 [2]and EN1090‐2 alternatively. The residual stresses are based on prEN1993‐1‐14 [2] and ECCS – Pub. No.33. In addition, analysis without the consideration of residual stresses are investigated. The scope is to assess the non‐linear finite element analysis (GMNIA), comparing the behavior of hot‐rolled and welded steel cross‐section as well as the impact of additional reinforced concrete encasement. Guidance for the numerical analysis for steel and composite columns is developed.
A Complete Assessment of the Moment‐Curvature Relationship of Compressed Steel‐concrete Composite Cross‐sections
Authors: Lemes Ígor J.M. , Lima Pedro H.A. , Barros Rafael C. , Silveira Ricardo A.M. , Chiorean Cosmin G.
Published: September 2022

In the non‐linear evaluation of the behavior of steel, concrete and steel‐concrete composite cross‐sections, increment and iteration strategies are necessary for the complete construction of the moment‐curvature relationship (M‐Φ). For the correct simulation of sections composed of strain‐softening materials, a numerical strategy based on constant force increments does not capture the downward branch of the M‐Φ relationship. Therefore, the present study aims to couple the strain compatibility method to the path‐following strategies to go beyond the critical bending moment points in the construction of the relations that describe the complete cross‐section mechanical behavior. In this context, the generalized displacement technique, which depends on a generalized stiffness parameter, and the minimum residual displacement method, are adapted to the cross‐sectional non‐linear problem. To validate the proposed numerical formulation, the results obtained here are compared with the numerical data available in the literature. Additionally, the softening effect on the concrete was increased to induce descending stretches in the moment‐curvature relationship, and this condition was correctly evaluated.
Application of Fibre Optical Sensors in Push‐out Tests on Composite Steel Truss and Concrete Beams
Authors: Kroyer Robert , Vigneri Valentino , Taras Andreas
Published: September 2022

Experimental push‐out tests have been playing an essential role for the evaluation of the structural behaviour of shear connectors in steel‐concrete composite beams along with the development of analytical design guidelines for predicting the respective longitudinal shear capacity. Although standard push‐out tests allow to quantify the global response of the specimen in terms of load‐slip behaviour, numerical simulations are usually needed to broaden the mechanical insight with a special focus to the areas involved in the mechanical failure. This holds in particular for composite steel truss and concrete beams, where a dedicated shear connection does not exist. The shear connection relies instead on a mechanical interlock between the steel parts and the concrete.

Modern measurement devices allow expanding the experimental insight to internal mechanisms of combined concrete‐steel failure. This paper reports on the instrumentation of push‐out tests on composite steel truss and concrete (CSTC) beams with the support of a distributed fibre optical sensing (DFOS) system and evaluates the experimental results. The content presents different concepts of fibre installation and discusses the respective rate of success and the measurement ranges along the global load‐slip curves of the push‐out specimens. The results from the DFOS system provide the strain field histories along essential structural elements embedded in concrete within a crucial range of the load‐slip curves. Hereby it was possible to gain more insight into the load‐bearing mechanisms and identify the material component most likely involved in the stiffness degradation of the push‐out specimens.
On the Verification of Beams Subjected to Lateral Torsional Buckling by Simplified Plastic Structural Analysis
Authors: Moscoso Caridad , Kraus Matthias
Published: September 2022

Plastic structural analysis may be applied without any difficulty and with little effort for structural member verifications with regard to lateral torsional buckling of doubly symmetric rolled I sections. Suchlike analyses can be performed based on the plastic zone theory, specifically using finite beam elements with seven degrees of freedom and 2nd order theory considering material nonlinearity. The existing Eurocode enables these approaches and the coming‐up generation will provide corresponding regulations in EN 1993‐1‐14. The investigations allow the determination of computationally accurate limit loads, which are determined in the present paper for selected structural systems with different sets of parameters, such as length, steel grade and cross section types. The results are compared to approximations gained by more sophisticated FEM analyses (commercial software Ansys Workbench applying solid elements) for reasons of verification/validation. In this course, differences in the results of the numerical models are addressed and discussed. In addition, results are compared to resistances obtained by common design regulations based on reduction factors χlt including regulations of EN 1993‐1‐1 (including German National Annex) as well as prEN 1993‐1‐1: 2020‐08 (proposed new Eurocode generation). Concluding, correlations of results and their advantages as well as disadvantages are discussed.
Simplified Interaction Conditions and their Accuracy in Doubly Symmetrical I‐Sections
Authors: Ludwig Christian
Published: September 2022

Doubly symmetric I‐sections are amongst the most common cross‐sections used in steel construction. Taking the class of the cross‐section into account, its load‐bearing capacity can be verified as either elastic or plastic. Considering plastic load‐bearing capacity has commercial and ecological advantages and it can be verified using interaction conditions specific to a particular cross‐section. In the technical standards and the literature, a variety of interaction conditions are given. The aim of this study is to compare and evaluate frequently occurring combinations of internal forces and moments (N‐My, N‐Mz, N‐My‐Mz und My‐Mz‐Mω). In addition, boundary conditions for the individual interaction conditions are explained in more detail. Extensive parameter studies have shown that the solutions in EN 1993‐1‐1 and prEN1993‐1‐1 lead to uneconomical and partially non‐conservative results. Through the use of the Extended exponent method (EXM) in combination with the Partial internal force method (PIM‐plus), very simple and reliable calculations can be performed.
Influence of Strain‐hardening on the Bending Strength and Rotation Capacity of Welded I‐section Beams
Authors: Studer Patrick , Taras Andreas
Published: September 2022

The bending strength and rotation capacity of welded I‐section beams made of four different steel grades with varying strain‐hardening characteristics are investigated in this paper. Therefore, four point bending tests are carried out on beams with different cross‐sections. These cross‐sections are assigned to cross‐section class 1 and 3 respectively and thus denote cross‐sections with different design approach. The central areas of the beams were scanned to determine the initial imperfections. The newly developed steel grade, which exhibits a pronounced hardening behavior, achieves a higher bending strength as well as a greater rotational capacity compared to the conventional steel grades. With DIC measurements, the deformation field as well as the resulting strains and stresses over the height of the web could be investigated during the tests. By parameterized numerical simulations, it was possible to identify the shape of the initial imperfection as relevant parameter. By comparing the outcome of the numerical simulations with the experimental investigations, a verified numerical model could be developed, which can be used for further investigations on cross‐section classification.
Lateral Bracing Stiffness Requirements for Systems of Parallel Compression Members
Authors: Ziemian Constance , Ziemian Ronald
Published: September 2022

Practical models have been developed to determine the threshold stiffness for lateral bracing components used in systems of parallel compression members or sub‐assemblages. Model formulation is based on the analysis of n parallel compression members with intermediate tie‐bracing and flexible anchorages. Intermediate bracing options include both continuous lateral tie‐bracing with flexible shear connectors, and discrete tie‐braces (blocking) directly linking adjacent members without connectors. Anchor bracing cases include both rigid and flexible braces and connectors, and both equal and unequal stiffnesses. Analytical solutions for the threshold stiffness were derived using equilibrium, compatibility, and constitutive relationships for a system that modeled bracing with linear‐elastic springs. The resulting eigenvalue problem is solved with computational efficiency and speed that far exceeds that of a root‐finding solution scheme reliant on symbolic computations. Two approximate expressions for the ideal tie‐brace stiffness have also been developed. Comparisons with the exact solutions indicate satisfactory accuracy for both approximations, with mean percent errors of 1% ‐ 2% for realistic variable values. A design procedure using these approximations is also proposed.
Direct Conversion of Food Waste into 3D Porous Carbon Traps for Selective Adsorption of Cationic Dyes
Authors: Senthamizhan Anitha , Balusamy Brabu , Debellis Doriana , Heredia‐Guerrero Jose Alejandro , Mancini Giorgio , Carzino Riccardo , Ceseracciu Luca , Athanassiou Athanassia , Fragouli Despina
Published: September 2022

Conversion of waste biomass into valuable functional materials accomplishes the concept of circular economy in the development of sustainable waste management, and also recovery of such resources possibly reduces the requirement of feedstocks. In this scenario, the development of methodologies toward the direct conversion of the raw biomass into solid adsorbent materials without the use of any templates is highly desirable, but exceptionally challenging due to the complexity of the process. Here the direct synthesis of 3D porous carbon traps by a simple, cost‐effective, and template‐free process starting from a kitchen‐based recipe and fermented food waste is described. Precisely, a robust carbon trap is formed with a spongy structure and highly interconnected hierarchical pores after the pyrolysis of a rice‐based foam in the air. The developed materials float on water and interact efficiently with cationic dyes at static conditions. Importantly, such performance of the 3D carbon traps is not affected in the presence of anionic dyes, indicating the excellent selectivity towards the adsorption of cationic dyes. The adsorbent can be easily recovered and reused for up to 3 cycles without releasing any byproducts, thus, without causing hazardous risk of any secondary pollution to the environment.
Sputum cell‐free DNA for detection of alterations of multiple driver genes in lung adenocarcinoma
Authors: Wang Zheng , Li Lin , Wang Yifei , Li Xiaoguang , Xu Yan , Wang Mengzhao , Liang Li , Wu Xiaonan , Tang Min , Li Yuanming , He Shurong , Du Jun , He Lei , Sun Mingjun , Yang Li , Di Jing , Gai Fei , Liu Dongge
Published: September 2022

Background

Sputum cell‐free DNA (cfDNA) has been confirmed to be a valued surrogate sample for detection of EGFR mutations in patients with lung adenocarcinoma (LAC). Whether it is suitable for detection of mutations of multiple driver genes has not been reported.

Methods

A total of 83 patients with LAC were enrolled and their sputum and paired tumor samples were collected. A next‐generation sequencing (NGS)‐based 10‐gene panel was used to test sputum supernatant‐derived cfDNA and paired tumor DNA. The sputum sediments were used for cytological evaluation.

Results

The total positive rates of hotspot mutations of the 10 driver genes in sputum cfDNA and matched tissue samples were 65.1% and 77.1%, respectively. The overall detection sensitivity of variants in sputum cfDNA was 81.3% (95% confidence interval [CI], 69.2%, 89.5%) and the specificity was 100% (95% CI, 79.1%, 100%). The sensitivities of testing sputum cfDNA from patients with stage IIIB‐IV was 87.0% (95% CI, 74.5%, 94.1%); the sensitivities of testing sputum cfDNA from patients with malignant sputum was 92.3% (95% CI, 78.0%, 98.0%); and the sensitivity of testing sputum cfDNA from patients with malignant sputum in stage IIIB‐IV were 94.1% (95% CI, 78.9%, 99.0%).

Conclusions

This study demonstrated that sputum cfDNA were successfully used for the detection of multiple driver genes by NGS. Sputum cfDNA could be a valuable surrogate clinical sample for all‐in‐one test of mutations to guide target therapies, especially for patients with advanced LAC and malignant sputum.