bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Operating Conditions on Graphene Properties Synthesized from Two-Step Electrochemical Exfoliation
Authors: Momodu Damilola , Madito Moshawe Jack , Singh Ashutosh Kumar , Sharif Farbod , Karan Kunal , Trifkovic Milana , Roberts Edward P.L. 
Published: December 2020

Effective exfoliation of relatively high-quality graphene with good yield from graphite is critical for its extensive exploitation in several emerging technologies. Two-step electrochemical exfoliation of graphene offers a route towards achieving such high-quality graphene and tailoring of its properties for nanotechnology-related applications. A precise control of the intercalation and exfoliation conditions provides an additional dimension for tuning these graphene properties.
Here, we report a systematic evaluation of the nature of defects induced in graphene with respect to varying intercalation times and intercalant composition using an acid-blend containing sulphuric acid (H2SO4) and phosphoric acid (H3PO4). A few-layer, exfoliated graphene (eG) is obtained by incorporating relevant functional groups in the main matrix during the intercalation step. Structural analysis by Raman and X-ray microscopy indicates a multi-atom-doped graphene with primarily “boundary
-type” defect signature and n-type charge carriers synthesized for an optimized intercalation time of 1600 s. The average ratio of the defect-activated modes (I

D

/
I

G
and I

D

/
I

D′
) showed a unique defect feature at 1600 s irrespective of the intercalating electrolyte composition. This indicates the need for careful selection of intercalation times to control the nature of defects. The phosphorus and nitrogen-doping content in the eG increased with increasing phosphoric acid content which influences the thermal and electrical conductivity respectively.
Most interesting, by using various intercalation times, we show that increasing intercalation times in the presence of high phosphoric acid content beyond 1600 s results in deteriorating electrical conductivity but enhanced thermal stability. A trade-off in conductivity and thermal stability shows competing factors influence these properties. We attribute this to loss of the sp2 graphitic structure at higher intercalation times which dominates over any contributions from the dopants. The highest electrical conductivity of ~14,000 S m-1 was recorded which is a two orders magnitude increase from the eG intercalated in pure H2SO4. The energy consumption (kWh kg-1) required for exfoliation was reduced by up to 50% and the exfoliation efficiency was enhanced with the incorporation of phosphoric acid into the intercalating electrolyte blend. This study thus provides a facile and energy-efficient recipe for synthesizing graphene nanostructures with unique defects relevant for use in specific applications related to energy storage and water treatment.

Figure 1
Relationship between Carbon Structure-Electrical Conductivity By Cluster Analysis for Li-Ion Battery Application
Authors: Moon J.M. , Chae S.W. , Pornaroontham P. , Naraprawatphong R. , Wang X. , Saito N. 
Published: December 2020

Carbon materials are widely used as anode on Li-ion battery (LIB). In particular, the effect of electrical conductivity (EC) on the anode is related to capacity and retention, which are important factors for LIB performance. However, the relationship between carbon properties and battery performance is still unclear. This uncertainty is due to the sp3 and sp2 bond states, the diversity of carbon like amorphous structures, and impurities.
In this study, we investigate the structure-EC relationship from over 50 carbon samples. The carbon used was graphite, carbon nanotube (CNT), carbon black (CB), hetero atom doped carbon, and the ones synthesized by solution plasma. The carbon materials are evaluated by X-ray diffraction (XRD), Raman spectroscopy, Thermogravimetric analysis (TGA), Energy-dispersive X-ray spectroscopy (EDX), and four-point probe (FPP) measurement. The characterized values were extracted from the results and analyzed by Cluster analysis (CA) with JMP software. CA was used to classify how carbons are related to each other.
The clusters were divided into 3 big groups according to the presence of 002 peak and the degree of defects. Some clusters have been shown high conductivity when they have high crystallinity. It was also found that the heteroatomic effect was higher than the crystallinity in the part showing low EC range. However overall correlation with EC is still unclear. This is because XRD and Raman can only provide information of symmetric or periodic structures rather than the effect of disorder or amorphous parts, sizes and shapes are not considered. Thus, analysis of shapes and sizes such as SEM and BET, and additional measurements related to amorphous structures may be helpful to clarifying the correlation.

Figure 1
Development of Complex Hydrogen Penetration Ratio As a New Transfer Function for Analysis on Hydrogen Penetration Mechanisms into Metals
Authors: Fukada Haruka , Hoshi Yoshinao , Watanabe Hikari , Shitanda Isao , Itagaki Masayuki 
Published: December 2020

Degradation of steels related to the hydrogen embrittlement is a serious problem from the standpoint of infrastructure preservation. The hydrogen embrittlement is related to the hydrogen penetration reaction (HPR) into steel. Some electrochemical methods [1-4] were employed to investigate the HPR mechanisms. One of the major electrochemical methods is electrochemical impedance spectroscopy (EIS). The EIS was applied to the investigation of HPR mechanisms because the time constants observed in impedance spectrum can be discriminated [5]. Another one is Devanatnan-Stachurski permeation technique [6, 7]. In this technique, two independent electrochemical cells are arranged on two surfaces of metal sheet and anodic and cathodic polarizations can be performed with each cell using the three-electrode system. The amount of hydrogen penetration rate can be evaluated by measuring the oxidation current of hydrogen atoms diffused in the metal sheet at the anode side. In this study, we proposed a new transfer function based on the electrochemical reactions and mass transfer during HPR by combining EIS and Devanatnan-Stachurski permeation technique. The complex hydrogen penetration ratio (CHPR), ι, as a new transfer function is defined from ratio of ΔI
per and ΔI
ent.

ι = ΔI
per / ΔI
ent (1)
In this equation, the ΔI
per is the current response related to the hydrogen penetrated through metal sheet at anode (detection) side, and the ΔI
ent is the current response of cathode (entry) side. The equation (1) can be expressed by the following equation as the theoretical equations for ΔI
per and ΔI
ent were derived based on Fick's 2nd law,.

ι = 1 / K
ab exp (-h (jω / D)1 / 2) (2)
In the equation (2), K
ab is the hydrogen entry ratio against the total cathodic reaction rate, h is the thickness of metal sheet, j is imaginary number unit, and D is the hydrogen diffusion coefficient.
The simulations of ι were conducted with the equation (2) assuming arbitrary values of D. The simulation results indicated that the phase shift of ι became large with the decrease of D. The new method to determine the value of D from the phase shift of CHPR was developed.
References:
[1] J. O'M. Bockris, J. McBreen, and L. Nanis, J. Electrochem. Soc, 112, 1025 (1965).
[2] A. Komatu, A. Nishikata, T. Tsuru, Zairyo-to-kankyo, 58, 269 (2009).
[3] A. Tada, E. Nishikata, ISJ internatonal, 56, 424 (2016).
[4] K. Fushimi, M. Jin, T. Nakanishi, Y. Hasegawa, T. Kawano and M. Kimura, ECS Electrochem. Lett., 3, C21 (2014).
[5] C. Gabrielli, P. P. Grand, A. Lasia, and H. Perrot, J. Electrochem. Soc., 151, A1943 (2004).
[6] M. A. V. Devanathan and Z. Stachurski, Proc. R. Soc. Lond. Ser. A, 270, 90 (1962).
[7] M. A. Devanathan and Z. Stachurski, J. Electrochem. Soc., 111, 619 (1964).
Internal Oxidation of High Strength Steels during Short-Term Annealing: Observation of Significant Enhancement of the Internal Oxidation in Fe-Mn-Si Ternary Alloys
Authors: Zhang Xue , Correa da Silva Caue , Rohwerder Michael 
Published: December 2020

In different production steps steels are exposed for short times, from a few minutes to up to a few hours, to high temperatures, either under reducing conditions for iron (e.g. N2-H2 during recrystallization annealing) or in oxidizing environments (e.g. during hot rolling and cooling after hot rolling). These processes are accompanied by external and internal oxidation, which can affect further processing steps. For example, during cooling after hot rolling of high strength steels especially grain boundary oxidation can lead to significant problems during pickling and cold rolling. For some alloys, e.g in the Fe-Mn-Si system, a surprisingly pronounced and deep grain boundary oxidation is observed.
In this paper a fundamental investigation of grain boundary oxidation during annealing under model atmospheres simulating the oxygen partial pressure beneath the scale and also under significant lower partial pressure will be addressed, based on model alloys which are relevant to industrial high strength steel grades. The focus will be on questions such as how the different alloying elements and different annealing conditions influence the internal selective oxidation.
In order to develop a fundamental understanding, the internal oxidation of dedicated binary and ternary model alloys (Fe-Mn, Fe-Si, Fe-Mn-Si, of different composition) was investigated in depth. Besides a thorough analysis of the oxide morphology, one important focus was on monitoring the mass gain in-situ during isothermal oxidation for short term exposures of up to 2h. The partial pressure of oxygen during the experiments was kept just below the equilibrium pressure for FeO/Fe and for comparison also at much lower partial pressure. As the mass changes during internal oxidation are very low, errors from buoyancy effects in a standard set-up are in the same range as the mass change to be investigated. Hence, a novel under-pressure TG set-up was developed and applied here. Furthermore, in-operando photoelectron spectroscopy of the oxide evolution at the surface by Ambient Pressure Photoelectron Spectroscopy (APXPS) was carried out, which provided important additional information for achieving a fundamental understanding of the observed oxidation kinetics. Based on the results the enhancing effect of the combination of Si and Mn on internal oxidation will be discussed.
Oxidation and Hot Corrosion Type I of Alternative Bond Coats for SiC/SiC Ceramic Matrix Composites
Authors: König Till , Galetz Mathias C. 
Published: December 2020

With the goal of increasing the combustion temperature and decreasing the weight of todays aero engines, the application of SiC/SiC ceramic matrix composites is widely investigated and first parts are in service. Besides the many advantages of SiC/SiC ceramic matrix composites, some challenges are encountered and have to be overcome to ensure a reliable operation. One of these challenges is the protection of the ceramic matrix composites from oxidation and volatilization. The oxidation of silicon carbide results in the formation of silicon dioxide, which is generally considered protective. The combustion atmosphere, however, contains water vapor and other contaminations. The water vapor results in the formation of volatile silicon hydroxide, while contaminations, like CMAS or Na2SO4, can result in spallation or an increase in oxidation rates. Also, the fiber matrix interface coatings are more prone to oxidation and need to be protected to avoid loss in mechanical properties. Therefore, a coatings system, consisting of an outer environmental barrier coating and an inner bond coat, is applied to SiC/SiC ceramic matrix composite when used in turbine engines.
Within this study alternative bond coats are developed mainly based on aluminum oxide formers, which are in itself less prone to volatilization at the designated temperature of 1200°C. The coating process is realized via chemical vapor deposition, which can coat complex parts cost effectively and without the need for a line-of-sight. The coatings provide a reservoir of the oxide forming species and therefore the oxide scale is able to heal upon crack formation or spallation. One of the developed coatings is based on an oriented aluminum nitride layer, which is in contrast to bulk AlN resistant to high temperature oxidation in humid air. The influence of the orientation and the chlorine content, which is present due to the coating procedure, on the increased oxidation resistance is investigated. Cyclic exposures are done to investigated spallation and cracking behavior due to mismatches in thermal expansion. Further, the resistance to hot corrosion type I is compared to other materials used or investigated for the hottest sections of turbine engines. The microstructure of the coatings was examined before and after the exposures using X-ray diffraction, scanning electron microscopy and electron beam microanalysis.
A Prodigy Child of the Dutch Revolt: Immediate ‘Precursors’ to Grotius on Just Revolt
Authors: Kubben Raymond 
Published: December 2020

Abstract
One of the odd things about Grotius’s thought is that he – advocate of a rebellious regime – was not very supportive of the right of resistance. Justifying the revolt at the time not only meant legitimizing the new regime he was serving; it also meant ruling out opposition against it. That posed an intricate puzzle; a puzzle Grotius solved by drawing on the theorizing on just revolt of the previous decades. This paper purports to show the connection between Grotius’s thought on just revolt and the intellectual and political environment in which Grotius came of age. It also sets out to show that the solution to the puzzle lies in the element of authority and the particular view taken on the constitutional position of the States in the Low Countries.1
Tales of Antifascism: International Survivors’ Organizations during the Cold War
Authors: Becker Maximilian 
Published: December 2020

Abstract
During the Cold War, international associations of resistance veterans were important transnational actors. Split along the political fault lines, an ‘antifascist’ stance was crucial to them, both in their memories of resistance against Nazi Germany and in their involvement in the propaganda campaigns of the Cold War. Due to its manifold activities, the pro-communist Fédération Internationale des Résistants (fir) was the most important of these international associations. Liberal and anti-communist organizations, like the Fédération Internationale Libre des Déportés et Internés de la Résistance (fildir), formed the counterpart to the fir. These organizations will serve as a point of comparison. This study transcends the prevailing national perspective, instead investigating the transnational memory of the survivors. It goes on to examine the consequences of the political changes in the ussr after Stalin’s death in March 1953, and Khrushchev’s ‘secret speech’ as well as the Hungarian Uprising and its suppression in 1956.
Is the Surface Salinity Difference between the Atlantic and Indo-Pacific a Signature of the Atlantic Meridional Overturning Circulation?
Authors: Nilsson Johan , Ferreira David , Schneider Tapio , Wills Robert C. J. 
Published: December 2020

AbstractThe high Atlantic surface salinity has sometimes been interpreted as a signature of the Atlantic meridional overturning circulation and an associated salt advection feedback. Here, the role of oceanic and atmospheric processes for creating the surface salinity difference between the Atlantic and Indo-Pacific is examined using observations and a conceptual model. In each basin, zonally averaged data are represented in diagrams relating net evaporation and surface salinity S. The data-pair curves in the –S plane share common features in both basins. However, the slopes of the curves are generally smaller in the Atlantic than in the Indo-Pacific, indicating a weaker sensitivity of the Atlantic surface salinity to net evaporation variations. To interpret these observations, a conceptual advective–diffusive model of the upper-ocean salinity is constructed. Notably, the –S relations can be qualitatively reproduced with only meridional diffusive salt transport. In this limit, the interbasin difference in salinity is caused by the spatial structure of net evaporation, which in the Indo-Pacific oceans contains lower meridional wavenumbers that are weakly damped by the diffusive transport. The observed Atlantic –S relationship at the surface reveals no clear influence of northward advection associated with the meridional overturning circulation; however, a signature of northward advection emerges in the relationship when the salinity is vertically averaged over the upper kilometer. The results indicate that the zonal-mean near-surface salinity is shaped primarily by the spatial pattern of net evaporation and the diffusive meridional salt transport due to wind-driven gyres and mesoscale ocean eddies, rather than by salt advection within the meridional overturning circulation.
Germline variation of Ribonuclease H2 genes in ovarian cancer patients
Authors: Polaczek Rahel , Schürmann Peter , Speith Lisa-Marie , Geffers Robert , Dürst Matthias , Hillemanns Peter , Park-Simon Tjoung-Won , Liebrich Clemens , Dörk Thilo 
Published: December 2020

AbstractEpithelial ovarian carcinoma (EOC) is a genetically heterogeneous disease that is partly driven by molecular defects in mismatch repair (MMR) or homology-directed DNA repair (HDR). Ribonuclease H2 serves to remove mis-incorporated ribonucleotides from DNA which alleviates HDR mechanisms and guides the MMR machinery. Although Ribonuclease H2 has been implicated in cancer, the role of germline variants for ovarian cancer is unknown. In the present case-control study, we sequenced the coding and flanking untranslated regions of the RNASEH2A, RNASEH2B and RNASEH2C genes, encoding all three subunits of Ribonuclease H2, in a total of 602 German patients with EOC and of 940 healthy females from the same population. We identified one patient with a truncating variant in RNASEH2B, p.C44X, resulting in a premature stop codon. This patient had high-grade serous EOC with an 8 years survival after platinum/taxane-based therapy. Subsequent analysis of TCGA data similarly showed a significantly longer progression-free survival in ovarian cancer patients with low RNASEH2B or RNASEH2C expression levels. In conclusion, loss-of-function variants in Ribonuclease H2 genes are not common predisposing factors in ovarian cancer but the possibility that they modulate therapeutic platinum response deserves further investigation.
Serum defensin levels in patients with systemic sclerosis
Authors: Gedik Tugce Emiroglu , Kucuk Hamit , Goker Berna , Haznedaroglu Seminur , Pasaoglu Hatice , Varan Ozkan , Ozturk Mehmet Akif , Pasaoglu Ozge Tugce , Tufan Abdurrahman 
Published: December 2020

AbstractBackgroundSystemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of skin and lung as well as involvement of kidney, gastrointestinal system and heart. Aetiology and exact mechanism of disease is poorly understood. The association between antimicrobial peptides (AMPs) and other diseases such as idiopathic pulmonary fibrosis, diffuse panbronchiolitis, pulmoner alveolar proteinosis and psoriasis have been reported. A small number of studies have examined the role of AMPs on autoimmune diseases which has not been studied in scleroderma yet. We aimed to investigate AMP serum levels and their association with disease characteristics of SSc.MethodsForty-two patients (40 female, mean age 42 years) and 38 healthy subjects (32 female, mean age 38 years) were enrolled. For SSc patients, the following data were recorded: disease subset (limited/diffuse), autoantibodies (antinuclear, anti-centromere (ACA), and anti-SCL-70), blood tests, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), modified Rodnan skin score, presence and history of digital ulcers, kidney, gastrointestinal disease and lung involvement assessed by computed tomography and pulmonary function tests. Association between serum AMPs and disease characteristics were analysed.ResultsTwenty-nine of the patients had diffuse (69%) and 13 of the patients had limited (31%) systemic sclerosis. Average disease duration was 5.5 years. Pulmonary involvement was detected in 20 patients (47.6%). Serum concentration of alpha defensin was higher than healthy subjects (563 ± 415 vs 377 ± 269 ng/mL,p = 0.02). However, no difference was observed for beta-1 and beta-2 defensins in SSc patients and healthy controls. In sub-group analysis patients with interstitial lung disease had higher levels of alpha defensin than those without lung involvement (684 ± 473 vs 430 ± 299 ng/ml,p = 0.04). There was also correlation between alfa defensin serum concentrations and CRP (r = 0.34).ConclusionsAlpha defensin levels are increased in scleroderma patients and correlated with lung involvement indicating a role in the pathogenesis of disease.Trial registrationThis study is not a clinical trial study.
Developing excellence in biostatistics leadership, training and science in Africa: How the Sub-Saharan Africa Consortium for Advanced Biostatistics (SSACAB) training unites expertise to deliver excellence
Authors: Chirwa Tobias F. , Matsena Zingoni Zvifadzo , Munyewende Pascalia , Manda Samuel O. , Mwambi Henry , Kandala Ngianga-Bakwin , Kinyanjui Samson , Young Taryn , Musenge Eustasius , Simbeye Jupiter , Musonda Patrick , Mahande Michael Johnson , Weke Patrick , Onyango Nelson Owuor , Kazembe Lawrence , Tumwesigye Nazarius Mbona , Zuma Khangelani , Yende-Zuma Nonhlanhla , Omanyondo  Ohambe Marie-Claire , Kweku Emmanuel Nakua , Maposa Innocent , Ayele Birhanu , Achia Thomas , Machekano Rhoderick , Thabane Lehana , Levin Jonathan , Eijkemans Marinus J.C. , Carpenter James , Chasela Charles , Klipstein-Grobusch Kerstin , Todd Jim 
Published: December 2020

The increase in health research in sub-Saharan Africa (SSA) has led to a high demand for biostatisticians to develop study designs, contribute and apply statistical methods in data analyses. Initiatives exist to address the dearth in statistical capacity and lack of local biostatisticians in SSA health projects. The Sub-Saharan African Consortium for Advanced Biostatistics (SSACAB) led by African institutions was initiated to improve biostatistical capacity according to the needs identified by African institutions, through collaborative masters and doctoral training in biostatistics. SACCAB has created a critical mass of biostatisticians and a network of institutions over the last five years and has strengthened biostatistics resources and capacity for health research studies in SSA. SSACAB comprises 11 universities and four research institutions which are supported by four European universities. In 2015, only four universities had established Masters programmes in biostatistics and SSACAB supported the remaining seven to develop Masters programmes. In 2019 the University of the Witwatersrand became the first African institution to gain Royal Statistical Society accreditation for a Biostatistics Masters programme. A total of 150 fellows have been awarded scholarships to date of which 123 are Masters fellowships (41 female) of whom 58 have already graduated. Graduates have been employed in African academic (19) and research (15) institutions and 10 have enrolled for PhD studies. A total of 27 (10 female) PhD fellowships have been awarded; 4 of them are due to graduate by 2020. To date, SSACAB Masters and PhD students have published 17 and 31 peer-reviewed articles, respectively. SSACAB has also facilitated well-attended conferences, face-to-face and online short courses. Pooling of limited biostatistics resources in SSA combined with co-funding from external partners has shown to be an effective strategy for the development and teaching of advanced biostatistics methods, supervision and mentoring of PhD candidates.