bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel LC-MS/MS method for the simultaneous analysis of selected fat-soluble vitamins in serum obtained from pediatric patients with pneumonia
Authors: Zhang Min , Huang XiaoLan , Song MeiYan , Mi Lala , Yin Yan , Wang Fang , Chen Min , Zhang Ting , Yang Jian , Cui XiaoDai
Published: May 2022

The simultaneous quantification of selected fat-soluble vitamins in serum from pediatric pneumonia patients was carried out using a LC-MS/MS method.
Controlled synthesis of SPION@SiO2nanoparticles using design of experiments
Authors: Harman Clarissa L. G. , Mac Fhionnlaoich Niamh , King Aaron M. , Manning Joseph R. H. , Lin Wu , Scholes Peter , Guldin Stefan , Davies Gemma-Louise
Published: May 2022

A Design of Experiments approach was used to optimise synthesis of core@shell SPION@silica nanoparticles. Multiple linear regression analyses established relationships between the applied experimental variables and resulting particle properties.
Piperazine tethered bergenin heterocyclic hybrids: design, synthesis, anticancer activity, and molecular docking studies
Authors: Venkateswara Rao Banoth , Pavan Kumar P. , Ramalingam Vaikundamoorthy , Karthik G. , Andugulapati Sai Balaji , Suresh Babu K.
Published: May 2022

Novel piperazine-linked bergenin derivatives were synthesized and the compounds 5a, 5c, 10f, and 13o showed excellent cytotoxic activity. These compounds arrest the cell cycle and induce apoptosis by regulating the Bax/BcL2 expression.
A ferroelastic molecular rotator [(Me2N(CH2)2NH3)(18-crown-6)]triflate with dual dielectric switches
Authors: Lun Meng-Meng , Zhang Tie , Su Chang-Yuan , Li Jie , Zhang Zhi-Xu , Fu Da-Wei , Lu Hai-Feng
Published: May 2022

The crown ether-based molecular rotator [(Me2N(CH2)2NH3)(18-crown-6)]triflate reveals excellent ferroelasticity and dual dielectric switching feature.
Density functional theory study of a two-atom active site transition-metal/iridium electrocatalyst for ammonia synthesis
Authors: Song Wei , Fu Zhe , Liu Xiao , Guo Yongliang , He Chaozheng , Fu Ling
Published: May 2022

In this study, the key findings are that the para doped Mn2@Ir(100) catalyst affords excellent NH3 selectivity and NRR activity with an extremely low free energy barrier of 0.36 eV.
Les troubles musculo-squelettiques des praticiens en orthodontie en France : enquête par auto-questionnaire
Authors: Terracina Marion , Thierry Aurore , Mailloux Aurélie
Published: May 2022

Introduction : les troubles musculo-squelettiques (TMS) représentent la première cause de maladies professionnelles indemnisées. Bien que l’orthodontiste soit davantage exposé que la population générale aux différents facteurs de risque, il existe peu de données à ce sujet. L’objectif principal de l’étude est de réaliser un état des lieux de la situation épidémiologique des TMS chez les orthodontistes exerçant en France. Matériel et méthodes : un questionnaire a été adressé aux orthodontistes de France en septembre 2020. Un logiciel d’analyse statistique et l’aide d’une biostatisticienne ont permis la réalisation des analyses statistiques. Résultats : 506 praticiens ont répondu au questionnaire et 84% de l’échantillon a présenté des TMS au cours des 12 derniers mois. Les femmes (p=0,011) et les praticiens âgés (p=0,02) ont été les plus concernés. Le stress, le nombre d’années d’exercice et le nombre de patients par semaine ont été des facteurs significatifs d’apparition des douleurs. Le cou, le dos et les épaules ont été les zones les plus fréquemment citées. La répétitivité de certains gestes (n=243) et la posture de travail inconfortable (n=227) ont été les causes les plus souvent évoquées. Cependant, la plupart des praticiens semblent parvenir à gérer leurs douleurs sans arrêter leur activité professionnelle. Discussion et conclusion : bien que les facteurs de risque d’apparition des TMS soient bien identifiés, ils restent un problème majeur de santé publique. Une formation universitaire et en in-office au sujet des moyens ergonomiques pour prévenir les TMS pourraient diminuer leur survenue.
Comparison of molecular diagnostic approaches for the detection and differentiation of the intestinal protistBlastocystissp. in humans
Authors: Šloufová Martina , Lhotská Zuzana , Jirků Milan , Petrželková Klára J. , Stensvold C. Rune , Cinek Ondřej , Pomajbíková Kateřina Jirků
Published: May 2022

Blastocystisis the most commonly found intestinal protist in the world. Accurate detection and differentiation ofBlastocystisincluding its subtypes (arguably species) are essential to understand its epidemiology and role in human health. We compared (i) the sensitivity of conventional PCR (cPCR) and qPCR in a set of 288 DNA samples obtained from stool samples of gut-healthy individuals, and (ii) subtype diversity as detected by next-generation sequencing (NGS) versus Sanger sequencing. Real-time PCR resulted in more positive samples than cPCR, revealing high fecal load ofBlastocystisbased on the quantification curve in most samples. In subtype detection, NGS was largely in agreement with Sanger sequencing but showed higher sensitivity for mixed subtype colonization within one host. This fact together with use of the combination of qPCR and NGS and obtaining information on the fecal protist load will be beneficial for epidemiological and surveillance studies.
New Measures, Old Conclusions: Obesity Does Not Worsen Outcomes after Elective Abdominal Aortic Aneurysm Repair
Authors: Wall Joshua John Sommerville , Boag Katie F. , Waduud Mohammed A. , Pabale Keleabetswe , Wood Benjamin , Bailey Marc , Scott Julian A.
Published: May 2022

Background The “obesity paradox,” whereby the body mass index (BMI) mortality curve is “U-shaped,” is a well-studied phenomenon in vascular surgery. However, there has been an overreliance on BMI as the measure of obesity, which has shown to poorly correlate with clinical outcomes. Robust measures such as waist-hip ratio (WHR) have been suggested as a more accurate marker reflecting central obesity.

Objectives The objectives of this study were to evaluate the correlation between BMI and WHR on postoperative morbidity and mortality after elective abdominal aortic aneurysm (AAA) repair.

Methods Data were collected from the Leeds Vascular Institute between January 2006 and December 2016. The primary outcome was mortality and secondary outcomes included length of stay (LOS) and all-cause readmission. Binary logistic regression, linear regression, and correlation analysis were used to identify associations between BMI and WHR in relation to outcome measures.

Results After exclusions, 432 elective AAA repairs (281 open surgical repair [OSR] and 151 endovascular aneurysm repairs [EVARs]) were identified to be eligible for the study. The combined 30-day and 4-year mortality was 1.2 and 20.1%, respectively. The 30-day readmission rate was 3.9% and the average LOS was 7.33 (standard deviation 18.5) days. BMI data was recorded for 275 patients (63.7%) and WHR for 355 patients (82.2%). Logistic regression analysis highlighted no association between BMI and WHR with mortality, readmission, or LOS following OSR or EVAR.

Conclusion The results of this study suggest patients should not be denied treatment for AAA based on obesity alone.
Through-and-Through Brachio/Radio-Femoral Access Technique for Endovascular Recanalization of the Left Subclavian Artery
Authors: Erben Young , Lin Michelle , Franco-Mesa Camila , Huang Josephine F. , Sandhu Sukhwinder S. , Miller David , Tawk Rabih G.
Published: May 2022

The authors illustrate the use of through-and-through brachio/radio-femoral access technique in two patients who presented with subclavian steal syndrome. This is an additional tool in the armamentarium of the endovascular specialist to improve management of complex cases with subclavian steal syndrome. This technique provides several advantages to improve efficiency and precision of the procedure while reserving the open surgical bypass option if needed.
Direct Innominate Artery Cannulation versus Side Graft for Selective Antegrade Cerebral Perfusion during Aortic Hemiarch Replacement
Authors: Gergen Anna K. , Kemp Cenea , Ghincea Christian V. , Feng Zihan , Ikeno Yuki , Aftab Muhammad , Reece T. Brett
Published: May 2022

Background Selective antegrade cerebral perfusion (SACP) has become our preferred method for cerebral protection during open arch cases. While the initial approach involved sewing a graft to the innominate artery as the arterial cannulation site, our access strategy has since evolved to central aortic cannulation with use of a percutaneous cannula in the innominate for SACP. We hypothesized that SACP delivered via direct innominate cannulation using a 12- or 14-Fr cannula results in equivalent outcomes to cases utilizing a side graft.

Methods This was a single-center, retrospective analysis of 211 adult patients who underwent elective hemiarch replacement using hypothermic circulatory arrest with SACP via the innominate artery between 2012 and 2020. Urgent and emergent cases were excluded.

Results A side graft sutured to the innominate was utilized in 81% (n = 171) of patients, while direct innominate artery cannulation was performed in 19% (n = 40) of patients. Baseline patient characteristics were similar between groups aside from a higher baseline creatinine in the direct cannulation group (1.3 vs. 0.9, p = 0.032). Patients undergoing direct cannulation demonstrated shorter cardiopulmonary bypass time (132.7 vs. 154.9 minutes, p = 0.020) and shorter circulatory arrest time (8.1 vs. 10.9 minutes, p = 0.004). Nadir bladder temperature did not significantly differ between groups (27.2°C for side graft vs. 27.6°C for direct cannulation, p = 0.088). There were no significant differences in postoperative outcomes.

Conclusion Direct cannulation of the innominate artery with a 12- or 14-Fr cannula for SACP during hemiarch replacement is a safe alternative to using a sutured side graft. While cardiopulmonary bypass and circulatory arrest times appear improved, this is likely attributable to accumulation of experience and proficiency in technique. However, direct innominate artery cannulation may facilitate quicker completion of these procedures by eliminating the time necessary to suture a graft to the innominate artery.
Pockels modulation in integrated nanophotonics
Authors: Thomaschewski M. , Bozhevolnyi S. I.
Published: May 2022

Electro-optic modulators provide the electrical control of the intensity, frequency, and phase of an optical signal. They became an indispensable part of our telecommunication network and largely dictate the achievable data bandwidths. Novel active material platforms and recent advantages in fabrication and processing techniques enabled the next generation of electro-optic modulators featuring significantly improved performance in the relevant device metrics, i.e., modulation efficiency, bandwidth, wavelength range of operation, device footprint, and environmental stability. Here, we overview recent achievements of electro-optic modulation, consider tradeoffs between the performance matrices, and conduct an assessment of electro-optic modulators based on the relevant nanophotonic device configurations and material platforms. We highlight the fundamental limitations and practical challenges for different electro-optic materials employed in photonic and plasmonic device platforms.
Best practices in renewable energy resourcing and integration
Authors: Coimbra Carlos F. M.
Published: May 2022

Renewable energy resourcing and forecasting are enabling technologies for low-cost integration of increasingly higher market penetration of low-carbon power generation into the grid. The “Best Practices in Renewable Energy Resourcing and Integration” Special Collection Issue in the Journal of Renewable and Sustainable Energy covers best practices in solar and wind forecasting for renewable energy integration and includes datasets for testing, development, and for the augmented reproducibility of methods and results. This Special Collection focuses on manuscripts containing methodologies that substantially advance the state-of-the-art in renewable resourcing and forecasting.
Effect of dissimilatory iron reduction and
Authors: Shu Yao , Gong Xiaofeng , Li Yuanhang , Sun Yuheng , Niu Danni , Ye Hongting
Published: May 2022

Environmental context Dissimilatory iron reduction and Carex-produced dissolved organic matter (DOM) have an important influence on Cr(VI) reduction by the Fe(III)-reducing bacterium Enterobacter. The role of Carex DOM and ferrihydrite in the biotransformation of Cr(VI) by the bacterial isolate was investigated. The findings should help underpin the remediation and detoxification of chromium in anaerobic environments, and provide promising insights into the quaternary system of bacterium/Fe(III)/Cr(VI)/DOM. Rationale FeIII oxides and organic matter are important factors influencing CrVI degradation in wetland soils. However, it remains unclear how they interact in anaerobic systems. Methodology In this study, a strain of iron-reducing bacterium was isolated from Poyang Lake Wetland and identified as Enterobacter sp. PY16 (PY16) by PCR-16S-rDNA sequence analysis. Moreover, microbial reduction of FeIII/CrVI by PY16 and their mutual transformation in the quaternionic system of PY16/ferrihydrite/CrVI/dissolved organic matter (DOM, extracted from Carex cinerascens) were investigated. Results The results showed that PY16 could directly participate in the reduction of ferrihydrite and CrVI. The rate of CrVI reduction decreased with the increase of initial CrVI concentration, while it was enhanced by 2.78–42.99% in the presence of ferrihydrite. Moreover, 15 mg L−1 CrVI was almost eliminated after 72 h and the content of FeII increased by 78.21 mg L−1 in the presence of DOM. Discussion The fastest CrVI reduction rate occurred when ferrihydrite and DOM coexisted in the system, mainly because the promoting effect of DOM on ferrihydrite synergistically promoted CrVI reduction. DOM and FeII produced during the ferrihydrite reduction process served as electron shuttles that promoted CrVI reduction by a biochemical redox pathway. However, the electron transfer and donation capacity of DOMox/DOMred and FeIII/FeII in the reaction process still need to be further studied. Implications for future research The results underscored the importance of FeIII oxides and DOM on microbial CrVI reduction, thus providing a valuable technique to remove and detoxify chromium in wetland soils.
Thermodynamics of black string from Rényi entropy in de Rham–Gabadadze–Tolley massive gravity theory
Authors: Sriling Peerawat , Nakarachinda Ratchaphat , Wongjun Pitayuth
Published: May 2022

The de Rham–Gabadadze–Tolley black string solution is a cylindrically symmetric and static solution of the Einstein field equation with graviton mass term. For the asymptotically de Sitter solution, it is possible to obtain the black string with two event horizons corresponding to two thermodynamic systems. The Rényi entropy is one of the entropic forms which is suitable to deal with nonextensive properties of the black string. In this work, we investigated the possibility to obtain a stable black string by using the Rényi entropy in both separated and effective approaches. We found that the nonextensivity provides the thermodynamically stable black string with moderate size in both approaches. The transition from the hot gas phase to the moderate-sized stable black string in the separated/effective description is a first-order/zeroth-order phase transition. The significant ways to distinguish the black string from both approaches are discussed.
Physical aging and rejuvenation in the vortex matter of superconducting Nb50Zr50
Authors: Chandra Jagdish , Singh Rashmi , Manekar Meghmalhar
Published: May 2022

We report the experimental evidence of physical aging and rejuvenation in the vortex matter of a conventional low-T

C
superconducting Nb50Zr50 alloy. The underlying naturally formed microstructure indicates a landscape of pinning potential for the flux lines, on the basis of which the pinning properties are explained. Magnetic relaxation measurements were used to construct the two-time auto correlation function which is a function of the measuring time ‘t’ and waiting time ‘t

w
’ after the vortex state is prepared. The main characteristic features of the phenomenon of physical aging, which are the breaking of time-translation invariance and dynamical scaling are seen. Successive aging of the vortex matter after following different histories in the (H, T) phase space is non-cumulative in nature, which is also known as the phenomena of rejuvenation. These experimental observations of relaxation dynamics along with the features of microstructure of our sample seem to agree with the theoretical models of aging phenomenon in a system of elastic lines pinned by random quenched disorder that leads to hierarchical modes of relaxation.
Amplification of mechanical quadratures using weak values
Authors: Carrasco Sergio , Orszag Miguel
Published: May 2022

An interferometric arrangement is proposed in which the technique of weak value amplification is implemented in order to enlarge the effect of a single photon on the quadratures of a movable mirror of an optical cavity. The photon interacts weakly with the mirror via radiation pressure and is postselected in the dark port of the interferometer. The real and imaginary parts of weak values of angular momentum type photonic operators produce an amplification of the mirror quadratures, which is large as compared to the scenario in which all photons are taken into consideration, i.e. when no postselection is performed. The effect is studied both for a mirror initialized in a thermal and coherent states. For a thermal state, the weak value amplification effect is boosted with the number of particles of the mirror, which occurs due to the imaginary part of the weak values.
Anisotropic tolman V solutions by decoupling approach in f(R,T
2) gravity
Authors: Sharif M , Iltaf Shazmeena
Published: May 2022

This paper investigates the behavior of anisotropic static spheres that are constructed by employing a minimal geometric deformation in the framework of

f

(
R
,

T

2

)

gravity (

T

2

=

T

ζ
ν

T

ζ
ν

,

R

is the Ricci scalar and

T

ζ
ν

is the energy-momentum tensor). We consider a spherical setup with two sources: seed and additional. It is assumed that the seed source is isotropic whereas the new source is responsible for inducing anisotropy. We deform the

g

r
r

component to split the field equations into two sets. The first array corresponds to the isotropic solution whereas the second set contains the effect of the anisotropic source. The system related to isotropic source is determined by the metric potentials of Tolman V solution while three solutions of the second set are constructed corresponding to three different constraints. The physical acceptability of all solutions is checked through energy conditions by employing the radius and mass of PSR J1614–2230 star. We also examine the stability, mass, compactness and redshift of the obtained solutions. We conclude that first two solutions satisfy the viability and stability criteria only for small values of the decoupling parameter while third solution is stable for its all possible values.
Non-minimally assisted chaotic inflation
Authors: Hyun Sang Chul , Kim Jinsu , Park Seong Chan , Takahashi Tomo
Published: May 2022

Conventional wisdom says that a chaotic inflation model with a power-law potential is ruled out by the recent Planck-BICEP/Keck results. We find, however, that the model can be assisted by a non-minimally coupled scalar field and still provides a successful inflation. Considering a power-law chaotic inflation model of the typeV∼φnwithn= {2, 4/3, 1, 2/3, 1/3}, we show thatn= 1/3 (n= {2/3, 1/3}) may be revived with the help of the quadratic (quartic) non-minimal coupling of the assistant field to gravity.
Expected

measurement precision with

production at the CEPC *
Authors: Liu Qi , Ran Kunlin , Huang Yanping , Li Gang , Ruan Manqi , Jin Shan , Sun Liang
Published: May 2022

A search for the dimuon decay of the Standard Model Higgs boson is performed using Monte Carlo simulated events to mimic data corresponding to an integrated luminosity of 5.6 ab

collected with the Circular Electron-Positron Collider detector in

collisions at

GeV. This study investigates the

process, and the expected significance considering only the statistical uncertainty in the data for a background-only hypothesis for a Higgs boson with a mass of 125 GeV is found to be 6.1

, corresponding to a precision of 19%. The systematic impacts from the background Monte Carlo statistical fluctuations are estimated to be negligible. Moreover, the dependence of the measurement accuracy on the muon momentum resolution of the CEPC detector is investigated. It is found that the muon momentum resolution must be better than 204 MeV to discover the

process at the nominal integrated luminosity. If the resolution is 100% worse than the designed parameter, the integrated luminosity must be greater than 7.2 ab

to reach 5

significance.
Proposal of a non-invasive spectrum diagnostic instrumentation for hard X-rays with high repetitions
Authors: Deng B. , Liu Z. , Yang H. , Zhang Q. , Deng H. , Liu B.
Published: May 2022

The X-ray free-electron laser (XFEL) is one of the most powerful tools in scientific frontiers due to its ultra-fast pulse duration and high peak brightness. The non-invasive, energy spectrum monitoring of XFEL pulses is an emerging demand to enhance its operation. This work proposes a non-invasive photo-electron spectrometer equipped with four time-of-flight assemblies to monitor the spectrum of high-repetition-rate XFEL. A comprehensive numerical model is established for start-to-end simulations of the instrumentation, through which the performance of the instrumentation is evaluated and optimized. The simulation results suggest that an energy resolution of 0.05 eV can be fully feasible for XFEL pulses around 1 keV. The position and angular response of the TOF assembly are also discussed, which indicates the transverse radius of XFEL pulses is smaller than 1 mm and that the collecting angle of the design is suitable for monitoring.
Subsurface Modeling using Gravity and TDEM in Jiken, Blora Regency
Authors: Aji W , Wahyudi E J , Warsa
Published: May 2022

Geophysics plays an essential role in imaging the subsurface condition of the earth. Gravity and time-domain electromagnetic method is geophysical method that can be used to visualize the subsurface condition. In this research, gravity and TDEM surveys have been carried out in Jiken, Blora Regency. Modeling technique is needed to obtain the subsurface model that bring information related to subsurface condition. Inversion modeling is applied separately to the gravity data and TDEM data, respectively. The density interface inversion modeling is used to gravity data.Subsurface condition is approached by three layers model with different density contrast values in each layer. In these schemes, the modeling process will determine the thickness for every layer. While for TDEM modeling,differential evolution technique is applied to model the TDEM data. The subsurface condition is approached by four layers model. In these schemes, the modeling process will determine the resistivity and thickness for every layer. Finally, the model obtained from gravity inversion modeling is integrated into the model from TDEM inversion data by overlaying the model.
Petrophysical Analysis and Acoustic Impedance Inversion to Determine the Storage Target of Carbon Dioxide in Gundih Block, Central Java
Authors: Annisa Tara , Sule Mohammad Rachmat , Fatkhan
Published: May 2022

A pilot project of Carbon Capture and Storage in Indonesia is being prepared in the Gundih field, Central Java. This project acquired Kujung formation as their target area. However, an alternative to that formation is being investigated with Kujung formation's data as a benchmark to determine the total capacity of storage in Gundih Block. To determine the other carbon dioxide storage target, several tests are needed, one of which is petrophysical analysis. The results of this analysis are porosity, permeability, and thickness of a reservoir. After determining the porosity cut off from the Well data, we use the acoustic impedance inversion approach to assess the spread of the reservoir laterally. In this paper, we estimated that the porosity ranges from 7-12% with an average permeability of 10 mD. After examining the lateral distribution of the reservoir through the inversion, we can roughly estimate the distribution of good porosity reservoir. With the same method and logs derived from Kujung formation, we estimate that the upside potential from Ngrayong formation has an average porosity of 30% and average permeability of 16 mD. which are good enough to become an area of interest. With these results, we conclude that determining the area of interest from other target formation through petrophysical analysis and acoustic impedance inversion is sufficient to determine reservoir areas in a formation, though further injection feasibility studies are needed to determine the feasibility of injection of CO2 in Ngrayong Formation.
Identification of Carbonate Reservoir Prospective Zones Using Rock Physics Approach and Extended Elastic Impedance (EEI) in “BAP” Field, South Sumatera Basin
Authors: Prayoga B A , Winardhi S
Published: May 2022

One type of reservoir that has a large enough potential is the carbonate reservoir. Carbonate reservoir has heterogeneity in relation to pore shape, so it is necessary to apply a specific rock physics approach and seismic inversion which takes into account the elastic parameters of the rock in order to know the prospect zone of the carbonate reservoir. The rock physics approach taken is to estimate the modulus of the matrix and the estimation of the aspect ratio shows that the prospect carbonate has an aspect ratio range of 0.10 - 0.30 dominated by the pore shape of the Stiff Pore. Seismic inversion shows using extended elastic impedance shows carbonate porous (Mu-Rho < 33 GPa*g/cc) and saturated hydrocarbons (Lambda-Rho < 40 GPa*g/cc) are in the middle area (around the well) where the lateral spread is getting thinner with a thickness of up to 10 ms. The prospect zone analysis from rock physics modeling and extended elastic impedance shows that reef Baturaja Formation carbonate is a zone that has a good reservoir quality dominated by a pore shape that develops is stiff pore.
Analysis of Ground Shear Strain (GSS) In Mapping, Liquefaction Vulnerability Potential Using HVSR (Horizontal To Vertical Spectral Ratio) Method. Case Study: Sepaku Subdistrict, North Penajam Paser Regency, East Kalimantan
Authors: Kusuma Wira Hadi , Sanny T.A.
Published: May 2022

East Kalimantan has been designated as the new Capital Province of Indonesia. The criteria for determining the relocation of the nation's capital have passed various studies in the placement of a new state capital, one of which is by reviewing disaster aspects such as the risk of earthquakes, volcanoes and tsunamis. Based on historical records of earthquakes that have occurred, East Kalimantan is not a completely safe area from potential earthquakes or tsunamis. By using the HVSR method, the authors tried to determine the value of Ground Shear Strain (GSS) in the research area, namely Sepaku District, Penajam Paser Utara Regency. The result show that there were three zones namely Zona A, Zone B and Zone C had GSS values in Sepaku Subdistrict with landslides, soil compaction and liquefaction potential, namely 0.4 - 0.54. The result of HVSR interpretation curve are based on the phenomenon of the resulting ground shear strain value in accordance with the geological conditions in the research area of the Sepaku Subdistrict, Penajam Paser Utara Regency, East Kalimantan in characterizing the soil profile in the study area.
Superplastic behaviour of AA5083 sheets in the presence of an oscillating load
Authors: Dastgiri M S , Fuerth Z , Kiawi L , Ryzer E , Green D E
Published: May 2022

The superplastic flow behaviour of AA5083 sheets was investigated at 450°C in the presence of a minor oscillating load. Uniaxial tensile specimens were tested to fracture at constant strain rates with a minor oscillating load superimposed onto the monotonically increasing tensile load. In each test, the oscillating load was applied as a sine wave having a constant amplitude of 0.5 N and a constant frequency. A series of tests was conducted in which the strain rate ranged from 0.001 to 0.4 s-1 and the frequency of the oscillating load ranged from 10 to 40 Hz. And other tensile specimens were subject to a constant mean load with a superimposed oscillating load until a predetermined elongation was reached. The flow behaviour of AA5083 showed a significant sensitivity to the oscillations although the tensile strengths remained practically unchanged. The addition of a minor oscillating load resulted in a 20% - 50% relative increase in fracture strain for the strain rates considered compared to the same tensile tests without oscillation. Finite element simulation of the tensile tests conducted at constant mean load with superimposed oscillations were carried out with LS-Dyna using material data obtained from the experiments. The numerical simulation results were compared with experimental results obtained under the same loading conditions to confirm their validity. The addition of a minor oscillating load led to greater uniformity in thickness in the specimen gauge. It can be concluded that superimposing a minor oscillating load during superplastic forming results in significantly greater deformation prior to fracture.
Warping and springback reduction in bending of U-profiles through partial heating over the cross-section
Authors: Hoffmann E. , Kolpak F. , Tekkaya A. E.
Published: May 2022

Bending of profiles is challenging due to the high stiffness and possible deformations in the process. Especially bending of profiles with asymmetric cross-section regarding the force initiation axis leads to unwanted warping of the bent profile. This warping results from the position difference between the force initiation axis and the shear center, implying torsion moments on the profile. To prevent profile warping the use of shape-bound tools or a change of the force initiation axis position are common practices, though these methods reduce the flexibility of the process. A new method to prevent profile warping during bending is the use of partial, cross-sectional heating. Due to thermal softening in one profile area a quasi-symmetric bending case is achieved, which changes the position of the stress-free fiber and thus reduces the torsion moment. In this work, the warping and springback behavior of partially heated U-profiles consisting of S500MC steel after a three-roll push bending process is investigated using experimental methods. Through partial heating of one profile area to up to 600°C, a warping reduction of 83 % and a springback reduction of 69 % were achieved.
Improved formability of HMGF components by preforming in an upset bulging process
Authors: Haase R , Werner M , Kräusel V , Alimov A , Sviridov A , Härtel S
Published: May 2022

Hot Metal Gas Forming (HMGF) is a well-established combination of a profile hydroforming operation and an in situ hardening process. Roof rails and camshafts are typical applications. A significant limitation of the component geometry is the strain-related material thinning. In the polar coordinate system of the tube-shaped parts, the strain can be divided into circumferential and longitudinal portions. To achieve higher expansion ratios in circumferential direction, a longitudinal compression is necessary. In a conventional, non-tempered process setup this is achieved by an axial feeding movement during the forming operation. Under tempered conditions, in particular by friction coefficients well above 0.3, this is no longer possible in a controlled process. Anyhow, a beneficial material pre-distribution is required to enlarge the circumferential strain before material failure occurs. In the proposed preforming operation, the longitudinal compression is achieved by offset bulging. Based on aspect ratios between initial diameter, wall thickness, initial length and compression stroke, a specific, controlled wave pattern is achieved on the specimen. Subsequently, the semi-finished parts undergo the HMGF process in an austenitisation, transfer, forming and quenching procedure. By means of continuous, finite element based simulation and related model calibration in experimental trials, a significant increase in geometric complexity is achieved.
A case study of mechanical and thermal fatigue of press hardening dies
Authors: Chantziara K , Javadzadeh Kalahroudi F , Bergström J , Grehk M , Ulfberg P
Published: May 2022

Press hardening provides ultra-high strength steel components, typically boron steels, of complex geometries. In the process, the steel sheet is heated in a furnace to the austenitization temperature, transferred to the press, then simultaneously formed at high temperature and cooled in the die. Life limiting factors for the press hardening dies are mechanical fatigue, thermal fatigue, and wear. In the present case study two die segments were selected where critical damages were mechanical and thermal fatigue, respectively. The dies were made of a H13 type premium hot-work tool steel with complex heated die technology, die design integrating an advanced cooling system, for pressing automotive frame parts.

The first die failed due to mechanical loading with a crack initiated from the ejector pin area. The die design, the mechanical loads, the elevated temperature, and the tool steel crack resistance are main factors to consider. In the second die cracks initiated from an ejector pin hole, as well, due to thermal cycles causing alternating compressive and tensile stresses at the surface, which led to crack nucleation because of the accumulation of local plastic strain in the surface.
Improvement of shear cutting process by stress superposition via cross-elastic partholder
Authors: Briesenick D , Liewald M , Senn S
Published: May 2022

High quality requirements for shear-cut workpieces made of advanced sheet metal materials nowadays pose highest demands on cutting technologies. In this context, stress super-position in shear zones represents a common approach to adjust cutting surface quality or reduce trim load, but usually requires sophisticated process technologies. For example, fine blanking technology allows to increase clean-cut portion, but requires advanced tool and press technology. Given this background, the present paper deals with a novel, low-cost and straightforward approach of stress superposition in conventional shear cutting processes and tools. For this purpose, the partholder was geometrically modified to achieve vertical and horizontal force transmission into the blank. Presented investigations with implemented Z-shaped partholder and its cross-elasticity show a significant impact on cutting surface quality. The results were obtained by a numerical study using the FEA-Software DEFORM 2D, wherein geometry and process parameters were varied. By superposing compressive stresses, clean-cut portion could be increased up to 43 % compared to conventional shear cutting of DP600 having a sheet thickness of 1 mm. Additionally, rollover height was significantly reduced by up to 50 % due to the transversal forces of the cross-elastic partholder, while burr height could be kept constant.
Design Guidelines for interlocked stator cores made of CoFe sheets
Authors: Martin D M , Bäcker F , Deusinger B , Kubik C , Gehringer P , Schröder J , Groche P
Published: May 2022

CoFe lamination stacks used for high-performance electric motors can be manufactured economically in high volumes by interlocking. In order to ensure sufficient joint strength with minimized sheet thickness, a comprehensive knowledge of the influences of various process parameters, such as embossing depth, clearance and counter punch force, is essential. To analyze these parameters, which also influence the magnetic properties, experiments are carried out and resulting joint strengths are determined in top tensile tests. The negative influences of the cutting process on magnetic conductivity and thus hysteresis losses due to residual stresses and plastic deformation are well known. In the subsequent stacking step, an influence of embossing and pre-stresses on the material properties is expected. In addition, local electrical contacts between the sheets may occur due to the interlocking process, causing additional eddy currents. Loss measurements are conducted to investigate the effect of the joining process on the magnetic properties of the stack. In doing so, the influence of process parameters such as the embossing depth and clearance on eddy current power losses is analyzed.
Evaluation of hole expansion formability of high strength AA7075 alloy under varying temper conditions
Authors: Prasad Kali , Ebrahim Abrar Salam , Krishnaswamy Hariharan , Chakkingal Uday , Banerjee Dilip K.
Published: May 2022

There has been a widespread increase in the use of aluminum alloys in automotive industries for meeting ever-growing light-weighting requirements. However, edge formability is a critical manufacturing challenge that restricts their widespread use. Edge formability of sheet metal is determined using a hole expansion test (HET) and is evaluated by the hole expansion ratio (HER). The present study investigates the effect of temper conditions on the edge formability of AA7075 alloy sheets. Hole expansion tests were conducted in different temper such as W-temper (super saturated solid solution followed by water quenching), under aged (UA), and peak aged (PA) conditions. Two different hole preparation techniques, a punching and a drilling process, were used to prepare samples with varying edge conditions. The results demonstrate that the W-temper has the highest edge formability irrespective of hole edge conditions. Researchers have reported that uniaxial stress state prevails at the hole edge during the HET. Consequently, uniaxial tensile tests were conducted on for each temper condition and various tensile properties such as yield stress (YS), ultimate tensile strength (UTS), ratio of yield stress to ultimate tensile strength (YS/UTS) were determined to evaluate edge formability. Furthermore, microstructural and failure analysis of the failed specimens were performed to explain the deformation behavior during the HET.
Stretch flangeability of AHSS automotive grades versus cutting tool clearance, wear, angle and radial strain gradients
Authors: Larour P , Hinterdorfer J , Wagner L , Freudenthaler J , Grünsteidl A , Kerschbaum M
Published: May 2022

Stretch flangeability tests are performed on cold rolled AHSS automotive steel grades for crack sensitivity evaluation. The ISO16630 tests procedure is used with different cutting edge conditions including cutting clearance, cutting tool wear, cutting tool angle and hole expansion punch tool geometry. Among all influence parameters, the cutting clearance is considered to be the most critical to control. Low (<10%) and high (>20%) clearances are significantly detrimental to hole expansion ratio (HER). An optimum in HER is reached around 15% clearance. Both cutting punch wear and cutting die wear each affect negatively the HER values in comparison to new sharp cutting tools. Varying the cutting angle with concave and convex hole punching tool geometries instead of orthogonal cutting has a rather negative effect on stretch flangeability due to irregular cut edge quality along hole perimeter and excessive tool wear in the concave configuration. The influence of hole expansion punch geometry (flat R25, biaxial Nakajima R25 vs. ISO16630 60° conical) on the HER values is also investigated. The (true) HER values are proportional to the FE simulated logarithmic radial strain gradient at fracture.
Modeling tension-compression asymmetry and failure anisotropy in bending operations of a magnesium alloy
Authors: Steglich D , Besson J
Published: May 2022

The deformation behavior of the magnesium sheet alloy AZ31 at room temperature is investigated using different standard and non-standard mechanical tests as well as respective finite-element simulations. In order to address the bendability, three-point bending tests were performed for different orientations of the sample with respect to the sheets axes of orthotropy. The elastic-plastic deformation was modeled using a two-yield-surface model, which is able to describe the evolving strength differential effect as well as the anisotropy of the material. For the prediction of material failure, a numerically efficient damage criterion based on transformation of strain rates is calibrated and applied. It is shown that this model is able to predict the observed edge failure of specimens with good accuracy.
Effects of heavy Si doping on the structural and optical properties of n-GaN/AlN/Si(111) heterostructures
Authors: Zambrano-Serrano M A , Hernández Carlos A , de Melo O , Behar M , Gallardo-Hernández S , Casallas-Moreno Y L , Ponce A , Hernandez-Robles A , Bahena-Uribe D , Yee-Rendón C M , López-López M
Published: May 2022

n-GaN/ AlN heterostructures were grown by molecular beam epitaxy on Si(111) substrates.The GaN films were n-type doped with silicon and the effect of doping concentration on the structural and optical properties was studied. Si doping promotes a reduction of dislocation density as revealed by x-ray data analysis and Transmission Electron Microscopy. Furthermore, a decrease in the yellow band measured by Photoluminescence Spectroscopy was observed when silicon doping concentration was increased up to 1.7 × 1019 atoms cm−3. A particular mosaic structure was induced by the Si-doping as inferred from Rutherford Backscattering measurements. The crystal quality shows a small degradation for very heavily doped samples (1.3 × 1020 atoms cm−3).
Optimization of dry sliding wear behavior of epoxy nanocomposites under different conditions
Authors: Namdev Anurag , Purohit Rajesh , Telang Amit , Kumar Ashish , Saxena Kuldeep K , Mabuwa Sipokazi , Msomi Velaphi , Mohammed Kahtan A
Published: May 2022

This paper evaluates the wear properties of epoxy nanocomposites containing GNP (Graphene Nanoplatelets). In this research, variation of GNP (0,0.1, 0.25, and 0.5 wt%) were used to make nanocomposites. The hand layup technique was used for the fabrication of different composites. The Taguchi method is used to optimize the wear test and its related characteristics. Analysis of variance is used to understand the correlation between input variables and response measurements. Load (0.5, 1.0, 1.5, and 2.0 kg) and time (4, 6, 8, and 10 min) are the main variables for exploring wear characteristics for this study. It has been discovered that minimum wear in terms of mass loss and friction coefficient are minimum at 0.5 wt% GNP. Scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and RAMAN spectroscopy were used to characterize the wear mechanism. The result shows that the optimized value is closer to the experimental value.
Predictions of stress distribution and material flow in coining process for bi-material commemorative coin
Authors: Peng Yuchun , Xu Jiangping , Wang Yuan
Published: May 2022

Bi-material commemorative coins have the characteristics of weight reduction, beauty and corrosion resistance. However, due to different characteristics of bi-materials, defects such as stress concentration, drop of inner core and micro-cracks often occur at interface of materials in usage. Engineers usually employ multiple mold trials to check the bonding state of two material regions, judge the stress concentration area and modify the process to avoid micro-crack sprout. Based on the professional metal forming software Deform 3D, stress distribution and material flow in coining processes for single and bi- material commemorative coins are studied. Numerical examples demonstrate that there are three typical stages over the whole process whether the coin is single or bi- material. And stress concentrations appear at the corners of upper/lower dies and the material interface in case of bi-material. The former concentration lead to sprout of micro-cracks along the shear bands and the latter triggers cracks at the interface. In addition, two materials with different hardness are adopted in the core and ring, respectively, to investigate the mutual interaction behavior at interface. Numerical findings indicate that large strains occur at the edge and the interface in case of bi-material with soft core. These imply that deep adhesion happens at the interface in case of that soft material is in the core. It suggests that hard material in the inner core and soft one in the outer ring may cause falling of the core.
Exploration of the atomic-level structures of the icosahedral clusters in Cu–Zr–Al ternary metallic glasses via first-principles theory
Authors: Lu Wenfei , Wang Zhilue , Xiang Hongping , Feng Aihan , Shen Jun
Published: May 2022

The atomic-level structures of the icosahedral clusters in Cu–Zr–Al ternary metallic glasses were studied via the first-principles theory. The rules of icosahedra stability were determined. Icosahedra with a better chemical order or with a better symmetry exhibited a better stability. The strong connectivity between Al atom and Cu and Zr atoms was observed as demonstrated by the obvious degree of ‘bond shortening’. The Al atom contributed more to the structural stability when used as the central atom than the other atoms. Therefore, the addition of even a small amount of Al atom to the Cu–Zr binary system remarkably improved the stability of the icosahedron structures. The continued addition of Al atoms had a lower contribution to the improvement to the glass-forming ability of the Cu–Zr–Al alloys.
CATHAI: cluster analysis tool for healthcare-associated infections
Authors: Cuddihy Thom , Harris Patrick N A , Permana Budi , Beatson Scott A , Forde Brian M
Published: May 2022

Motivation

Whole genome sequencing (WGS) is revolutionizing disease surveillance where it facilitates high-resolution clustering of related organism and outbreak detection. However, visualizing and efficiently communicating genomic data back to clinical staff is crucial for the successful deployment of a targeted infection control response.

Results

CATHAI (cluster analysis tool for healthcare-associated infections) is an interactive web-based visualization platform that couples WGS informed clustering with associated metadata, thereby converting sequencing data into informative and accessible clinical information for the management of healthcare-associated infections (HAI) and nosocomial outbreaks.

Availability and implementation

All code associated with this application are free available from https://github.com/FordeGenomics/cathai. A demonstration version of CATHAI is available online at https://cathai.fordelab.com.