bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidative Cleavage of C−C Bonds in Non‐aromatic Oxygenates with Molecular Oxygen for Synthesis of Carboxylic Acids
Authors: Nakagawa Yoshinao , Yabushita Mizuho , Tomishige Keiichi 
Published: September 2023

AbstractOxidative carbon‐carbon cleavage reactions of non‐aromatic oxygenates such as vicinal diols are reviewed. In comparison with aromatic oxygenates where the benzyl positions are easily oxidized, non‐aromatic alcohols are difficult to be oxidized. The use of excess base in combination with metal catalysts is a typical approach, and the oxidations of 1,2‐cyclohexanediol and dihydroxylated derivatives of oleic acid have been reported with good yields of (di)carboxylate. Oxidation under acidic conditions typically uses vanadium as a key component of catalyst. Vanadium alone is active in oxidation of hydroxyketones and not effective in oxidation of saturated alcohols and polyols. Oxidation of sugars to formic acid is catalyzed by vanadium. For the oxidation of vicinal diols, the combination of platinum and vanadium is effective. There are some recently‐discovered systems for carbon‐carbon dissociation reactions of 1,2‐difunctionalized compounds, such as 2‐methoxycyclohexanone oxidation to adipic acid with polyoxometalate catalysts. On the other hand, the progress of research in the oxidation of cyclohexanone to adipic acid, which is an important industrial process, is less rapid, and we commented on the situation.
Cobaloxime‐Integrated Covalent Organic Frameworks for Photocatalytic Hydrogen Evolution Coupled with Alcohol Oxidation
Authors: Wang Shihuai , Wu Tai , Wu Shuyang , Guo Jingjing , He Ting , Wu Yinglong , Yuan Wei , Zhang Zhengyang , Hua Yong , Zhao Yanli 
Published: September 2023

AbstractWe report an azide‐functionalized cobaloxime proton‐reduction catalyst covalently tethered into the Wurster‐type covalent organic frameworks (COFs). The cobaloxime‐modified COF photocatalysts exhibit enhanced photocatalytic activity for hydrogen evolution reaction (HER) in alcohol‐containing solution with no presence of a typical sacrificial agent. The best performing cobaloxime‐modified COF hybrid catalyzes hydrogen production with an average HER rate up to 38 μmol h−1 in ethanol/phosphate buffer solution under 4 h illumination. Ultrafast transient optical spectroscopy characterizations and charge carrier analysis reveal that the alcohol contents functioning as hole scavengers could be oxidized by the photogenerated holes of COFs to form aldehydes and protons. The consumption of the photogenerated holes thus suppresses exciton recombination of COFs and improves the ratio of free electrons that were effectively utilized to drive catalytic reaction for HER. This work demonstrates a great potential of COF‐catalyzed HER using alcohol solvents as hole scavengers and provides an example toward realizing the accessibility to the scope of reaction conditions and a greener route for energy conversion.
Functionalized amino Al‐MOF as a novel fluorescence chemosensor for determination of Pb2+ in aqueous solution
Authors: Abu‐Melha Sraa 
Published: September 2023

Lead is an environmental pollutant that has been present for a long time and has harmful effects on human health. The essential task of protecting public health requires sensitivity and selectivity in monitoring and removing Pb2+ from the environment. NH2‐Al‐MOF was utilized to create a chemical sensor that can quickly detect Pb2+ ions. By combining the Al–metal–organic framework (MOF) with 2‐Acetyl‐4‐methylpyridine, the 2A4MP=N‐Al‐MOF sensor was developed. The NH2‐Al‐MOF and 2A4MP=N‐Al‐MOF sensor were characterized by X‐ray photoelectron spectroscopy (XPS), Brunner–Emmet–Teller (BET), X‐ray diffractometer (XRD), Fourier transform infrared (FT‐IR), and scanning electron microscopy (SEM). Characterization results indicate that 2‐Acetyl‐4‐methylpyridine was effectively incorporated into the Al‐based MOF, and the 2A4MP=N‐Al‐MOF sensor's pore structure is primarily made up of mesopores. To determine the optimal conditions for detecting Pb2+ ions using the 2A4MP=N‐Al‐MOF sensor via fluorescence measurement, several experimental studies have been carried out. A steady spectroscopic signal can be achieved with a sensor that has a response time of below 30 seconds. According to ICH guidelines, the suggested methods underwent validation for LOD, LOQ, linearity, and precision. The results show that the 2A4MP=N‐Al‐MOF chemosensor has a high sensitivity and selectivity toward the Pb2+ analyte, with a detection limit of 0.171 ppm and a linear range of 0.0–2.0 ppm. The 2A4MP=N‐Al‐MOF chemosensor also exhibited good reproducibility, with a relative standard deviation of less than 3%. As a result, the Pb2+ ions were sensitively and selectively identified in various environmental water samples using the 2A4MP=N‐Al‐MOF sensor.
Determining the structure and stability of essential oil‐sunflower wax and beeswax oleogels
Authors: Çokay Hatice , Öğütcü Mustafa 
Published: September 2023

AbstractIn this study, essential oil oleogels were produced using eucalyptus, lavender, lemon peel and tea tree oils with sunflower and beeswax. The physicochemical, thermal, textural, and structural features of the oleogels were determined. For the essential oils used, an addition level of less than 15% of beeswax (BW) was insufficient to form stable oleogels, whereas an addition level of 10% of sunflower wax (SW) was sufficient to form stable oleogels. The acid and peroxide values of the gels were higher than those of the oils. All of the oleogels exhibited peaks around 3.70 and 4.10, indicating the presence of β' polymorphic forms. The hardness and stickiness values of the oleogels were influenced by the type and level of wax addition, as well as the viscosity of the oil used. Based on the thermal analysis results, the oleogels based on beeswax exhibited lower melting properties compared to those based on sunflower wax. The thermogravimetric data indicated that the polymeric matrices formed by the waxes, which depended on the type and level of wax addition, affected the vaporization of the volatiles. In conclusion, oleogels represent a green and sustainable approach for reducing the loss of volatile or bioactive compounds from various essential oils, which are widely used in the food, cosmetics, and pharmaceutical industries.
Determination of cefuroxime in breast milk by LC–MS/MS using SALLME technique
Authors: Kul Aykut , Sagirli Olcay 
Published: September 2023

AbstractThe World Health Organization recommends that infants be exclusively breastfed for the first 6 months. Antibiotics are among the most commonly prescribed drugs for pregnant and lactating women. The vast majority of drugs pass into breast milk, which may create a risk for the infant. In cases where drug exposure may pose a risk, breastfeeding should be discontinued. Therefore, the mother's drug use should be decided by considering the most accurate and recent data. Cefuroxime is a second‐generation cephalosporin antibiotic with a broad spectrum of activity against Gram‐negative and ‐positive microorganisms. In this study, we aimed to develop the LC–MS/MS method using salt‐assisted liquid–liquid micro‐extraction (SALLME) for the determination of cefuroxime in breast milk. The method was validated according to the European Medicines Agency (EMA) guidelines. Cefuroxime and the internal standard cefixime were extracted from plasma by a SALLME technique. The results obtained from the entire validation study are at an acceptable level according to the EMA criteria. The calibration curve of cefuroxime was between 25 and 1000 ng/ml, with correlation coefficients of >0.99. The lower limit of quantitation was 25 ng/ml for cefuroxime. Furthermore, the developed method was applied for the determination of cefuroxime in real patient breast milk.
Performance of the 32 mm Myval transcatheter heart valve for treatment of aortic stenosis in patients with extremely large aortic annuli in real‐world scenario: First global, multicenter experience
Authors: Holzamer Andreas , Bedogni Francesco , van Wyk Pieter , Barwad Parag , Protasiewicz Marcin , Ielasi Alfonso , Nombela‐Franco Luis , Seidler Tim , Hilker Michael 
Published: September 2023

AbstractBackgroundExtremely large aortic valve anatomy is one of the remaining limitations leading to exclusion of patients for transcatheter aortic valve replacement (TAVR).AimsThe newly approved Myval 32 mm device is designed for use in aortic annulus areas up to 840 mm2. Here we want to share the initial worldwide experience with the device.Methods and ResultsRetrospective data were collected from 10 patients with aortic stenosis and very large annular anatomy (mean area 765.5 mm2), who underwent implantation with 32 mm Myval transcatheter heart valve at eight centers. Valve Academic Research Consortium‐2 device success was achieved in all cases. Mild paravalvular leak was observed in three patients and two patients required new pacemaker implantation. One patient experienced retroperitoneal hemorrhage caused by the contralateral 6 F sheath and required surgical revision. No device‐related complications, stroke, or death from any cause occurred within the 30‐day follow‐up period. In a studied cohort of 2219 consecutive TAVR‐screened patients from a central European site, only 0.27% of patients showed larger anatomy than covered by the 32 mm Myval device by instructions for use without off‐label use of overexpansion. This rate was significantly higher for the 34 mm Evolut Pro (1.8%) and 29 mm Sapien 3 (2.1%) devices.ConclusionsThe Myval 32 mm prosthesis showed promising initial results in a cohort of patients who previously had to be excluded from TAVR. It is desirable that all future TAVR systems accommodate larger anatomy to allow optimal treatment of all patients.
Why the Perfectly Symmetric Cobalt‐Pentapyridyl Loses the H2 Production Challenge: Theoretical Insight into Reaction Mechanism and Reduction Free Energies
Authors: Kiser Ayas , Gurdal Yeliz 
Published: September 2023

AbstractResearchers have extensively investigated photo‐catalytic water reduction utilizing Cobalt‐based catalysts with polypyridyl ligands. While catalysts exhibiting distorted polypyridyl ligand demonstrate higher H2 production yields, those with ideal octahedral coordination display poor performance. This outcome suggests the crucial role of ligand framework in catalytic activity, yet reasons behind the disparity in H2 production rates for catalysts with octahedral geometries remain unclear. We theoretically examined the water reduction mechanism of Co‐based poly‐pyridyl catalyst, CoPy5, having perfect octahedral coordination. We clarified the effect of octahedral coordination by utilizing each intermediate step of ECEC mechanism. We determined spin states, solvent response, electronic structures, and reduction free energies. CoPy5 with perfect octahedral coordination, alongside its distorted counterparts, exhibit similar spin states as the reaction progresses through each intermediate step. However, the first reduction free energy obtained for the CoPy5 is slightly higher than that of its distorted counterparts. Following the second protonation, resulting H2 molecule experiences limited diffusion from the Co center due to the compact structure of the CoPy5, which blocks the Co center for the next H2 production cycle. Catalysts having distorted octahedral geometries facilitate fast removal of H2 into the solvent. Thus, the reaction center becomes immediately available for subsequent H2 production.
Development of a preloadable, temperature‐stable, geopolymer‐based gap compensation material
Authors: Morgenstern Hendrik , Kunde Carsten , Raupach Michael 
Published: September 2023

AbstractConsequences of climate change are becoming increasingly clear and while resources are dwindling, extreme climatic situations become more frequent. This leads to higher temperatures and thermal stress on the one hand and to the construction of more wind power plants and respectively an increasing demand for gap compensation materials on the other hand. These materials are commonly made of epoxy resins, which perform well under certain circumstances, but have some disadvantages such as heat instability, high costs, high resource claim, and hazards for the environment and health. This paper presents the latest results from the development of a low‐viscosity, high‐temperature stable geopolymer for gap compensation. In several newly developed test rigs, experiments were carried out to investigate injectability, flow behavior, mechanical properties, high‐temperature stability, and the possibility to induce preload. Through inorganic additives, the geopolymer expands or, if expansion is constrained, preloads itself during the hardening. This is essential to retain or enhance the preload of connection bolts and ensure force transmission as any volume reduction would create a new (smaller) gap.
Experimental investigation on stress state and deformation in bolts through tightening of perfect flange connections
Authors: Schierl Christopher , Stang Andre , Ghafoori Elyas , Schaumann Peter 
Published: September 2023

AbstractThe fatigue loads of bolts in ring flange connections are significantly influenced by the pressure body between the compressed flanges, which in turn depends on two main scattering parameters ‐ geometric flange imperfections and the preload level. Depending on the tightening method and geometric boundary conditions, shear and bending stresses occur in addition to the axial stress in the bolt during prestressing of the connection. This multiaxial stress condition leads to different plastic deformations in the threads and thereby influence the performance respective the maximum achievable preload of tightening methods. In accordance with the objective, the authors identify the stress state in HV‐bolts during installation for different tightening procedures through experimental testing. Based on a comparison of the strain measurements with the 3D scan of the bolt geometry, this study evaluate to what extent the initial imperfections corresponds to bolt bending. Derived from the scope of a joint national research project, this contribution point out that the yield controlled tightening ensure prestresses close to the individual yield strength of the bolt within a narrow scatter.
Strength Evaluation of Pipe‐Rack Connection Using Extended End Plate
Authors: Kang Seong‐Hun , Woo Jong‐Hun , Shin Kyung‐Jae , Lee Woo‐Geun , Park Hwa‐In 
Published: September 2023

AbstractPipe‐rack structure is generally designed as a steel structure, but size of each column and beam is small because vertical loads on the structure is relatively low. In addition, due to the surrounding environment, the end plate joint is mainly used as on‐site bolting rather than welding. In this paper, seismic performance evaluation of pipe‐rack structures was conducted for three types of extended type end plate connection using the panel zone reinforcement and end plate thickness as variables. Connection of the pipe‐rack structure which is commonly used is the type of panel zone yielding occurred before other members, and its ductility and energy dissipation capacity was calculated 24.2% and 19.5% higher than the type of reinforcing panel zone by plates. As a result of the test, it is judged that yielding of the panel zone in a steel structure such as a pipe‐rack structure can be beneficial in the seismic loads.
Experiments on Welded High Strength Steel S700 K‐joints
Authors: Alshawwa Omar , Mela Kristo , Ahola Antti , Björk Timo 
Published: September 2023

AbstractHigh strength steel (HSS) hollow sections are widely available for structural applications nowadays. A typical structure employing HSS hollow sections is a truss with welded joints. The behavior and design of HSS welded tubular joints still includes some open issues, and so‐called K‐joints require more experiment‐based research. This research addresses the effect of specific parameters (chord preloading and the gap size) on the behavior of welded HSS K‐joints made from cold‐formed hollow sections. These parameters have been selected based on their limited conducted research. In the experiments the degree of chord tension preloading and gap size were varied to obtain a broad scope for the study. This study of the aforementioned parameters was conducted on 6 welded HSS K‐joints of grade S700. The study is entirely based on experiments targeting the effect of each parameter in a comparative manner. The tested joints were fabricated with full strength butt and fillet welds and were designed to target one type of failure in K‐joints to occur which is chord face failure. Subsequently, the load‐displacement behavior of the tested joints is reported. The experimental results are compared with the expected behavior according to the most recent version of the second generation Eurocode. The level of agreement between the tests and current guidelines is compared and analyzed. Accordingly, this research contributes to the ongoing discussion on behavior and resistance of welded HSS hollow section joints.
Simulation of Welding Residual Stresses in Large Structures – First Results of Thermal Analyses
Authors: Gkatzogiannis Stefanos , Gantes Charis 
Published: September 2023

AbstractSimulation of welding residual stresses and distortions has been applied mostly for small‐scale components, smaller than those applied in civil engineering structures, due to the high requirements in computational capacities. In the present study, work hypotheses, which can reduce the computational load of welding simulations for an accepted sacrifice in accuracy, are discussed. A series of thermal analyses is carried out, in order to check the validity of the proposed modelling approaches, which refer to the application of simple weld heat source models and hybrid shell‐solid element models. Application of local‐global models is also discussed. The present study aims to work as a first step towards the establishment of an engineering approach for the simulation of welds in civil engineering structures with sufficient accuracy and reduced requirements for computational capacity.
New analytical approach for predicting the plastic shear resistance of the panel zone in steel joints
Authors: Corman Adrien , Jaspart Jean‐Pierre , Demonceau Jean‐François 
Published: September 2023

AbstractThis paper presents a new analytical approach for predicting the plastic resistance of the sheared panel zone in steel beam‐to‐column joints. This approach has been developed within the framework of a larger research project dedicated to the prediction of the full non‐linear behaviour up to failure of the sheared panel zone. It is suggested as an alternative to the current European and North American design approaches, which are proved to be unsafe in many cases. This is demonstrated in this paper through comparisons with a non‐exhaustive sample of experimental results carefully selected from the scientific literature. In contrast, the new proposed expression, which more faithfully depicts the physical phenomena governing the resistance of the panel zone, provides safe estimates for all the investigated cases.
Innovative hollow section column‐splice connections resorting to laser cutting
Authors: Das Rajarshi , Kanyilmaz Alper , Couchaux Mael , Degee Herve 
Published: September 2023

AbstractCircular Hollow Section (CHS) columns are highly encouraged in the modern industry due to their good resistance against high compression, tension and flexure in all directions, combined with their exceptional aesthetics. However, conventional end plate‐bolted column‐splice connections tend to limit the full potential of the CHS by focusing most of the damages in the bolts and sometimes discourage architects with a poor aesthetic. An innovative “passing‐through” concept (using laser cutting technology) have therefore been proposed in the EU‐RFCS project LASTTS to develop efficient column‐splice connections. Three different configurations have been presented in this article: (1) CS‐1: CHS columns connected using passing‐through steel plates, bolts and steel cover plates outside the tube diameter; (2) CS‐2: CHS columns connected using passing‐through steel plates, bolts and steel cover plates inside the tube diameter; (3) CS‐3: CHS columns connected using passing‐through steel plates, bolts and steel end plates inside the tube diameter. Nonlinear parametric studies have been conducted based on finite element models, calibrated from a previous experimental campaign, to understand the influence of each parameter and subsequently characterize the analytical assumptions to calculate their ultimate resistance under different loads. Additionally, they are compared among each other to note their advantages/disadvantages in terms of strength, stiffness and industrial application.
Experimental study of the cyclic behavior of steel tube in concrete‐filled steel tube members
Authors: Wang Shiye , Wang Wei , Lignos Dimitrios G. 
Published: September 2023

AbstractA concrete‐filled steel tube (CFST) specimen was tested under uniaxial loading to acquire the nonlinear monotonic and cyclic response of the steel tube in CFST members including inelastic cyclic local buckling. The failure mode, hysteretic response, envelope curves, strength, and stiffness degradation of the CFST specimen were comprehensively studied. The observed failure modes of the CFST specimen were local buckling and ductile fracture of the steel tube due to ultra‐low‐cycle fatigue. The effective stress‐strain curve of the steel tube exhibited negative stiffness due to local buckling. The compressive resistance of the CFST specimen decreased significantly when local buckling progressed at the steel tube. The tensile unloading stiffness slightly decreased relative to the elastic stiffness of the CFST specimen; conversely the compressive unloading stiffness experienced severe deterioration upon increased cyclic loading. The tensile stiffness decreased gradually during the whole loading process, while the post‐capping stiffness remained stable.
Major‐axis buckling of pin‐ended stainless steel equal‐leg angle section members: FE modelling and design
Authors: Behzadi‐Sofiani Behnam , Wadee M. Ahmer , Gardner Leroy 
Published: September 2023

AbstractThe behaviour and design of cylindrically‐pinned stainless steel equal‐leg angle section members under compression and compression combined with strong‐axis bending are investigated herein. Numerical models are developed by means of shell finite element modelling formulated within ABAQUS and validated against experimental data. A numerical parametric study is then presented considering both hot‐rolled and cold‐formed stainless steel equal‐leg angle section columns alongside beam‐columns with a wide range of cross‐section and member geometries. Finally, new design proposals for pin‐ended stainless steel equal‐leg angle section members under compression and compression plus major‐axis bending are developed and verified against the results of physical experiments and numerical simulations. The proposed design rules are shown to offer substantially more accurate and consistent resistance predictions compared to existing codified design rules.