Axial Zone Research Articles

Total Third-Degree Variation for Noise Reduction in Atomic-Resolution STEM Images.

Scanning Transmission Electron Microscopy (STEM) enables direct determination of atomic arrangements in materials and devices. However, materials such as battery components are weak for electron beam irradiation and low electron doses are required to prevent beam-induced damages. Noise removal is thus essential for precise structural analysis of electron beam sensitive materials at atomic resolution. Total square variation (TSV) regularization is an algorithm that exhibits high noise removal performance. However, the use of the TSV regularization term leads to significant image blurring and intensity reduction. To address these problems, we here propose a new approach adopting L2 norm regularization based on higher-order total variation. An atomic-resolution STEM image can be approximated as a set of smooth curves represented by quadratic functions. Since the third-degree derivative of any quadratic function is 0, total third-degree variation (TTDV) is suitable for a regularization term. The application of TTDV for denoising the atomic-resolution STEM image of CaF2 observed along the [001] zone axis is shown, where we can clearly see the Ca and F atomic columns without compromising image quality.

Distinct molecular profile of the chick organizer as a stem zone during axial elongation.

The vertebrate organizer plays a crucial role in building the main (antero-posterior) axis of the embryo: it neuralizes the surrounding ectoderm, and is the site of emigration for cells making axial and paraxial mesendoderm during elongation. The chick organizer becomes a stem zone at the onset of elongation; it stops recruiting cells from the neighbouring ectoderm and generates all its derivatives from the small number of resident cells it contains at the end of gastrulation stages. Nothing is known about the molecular identity of this stem zone. Here, we specifically labelled long-term resident cells of the organizer and compared their RNA-seq profile to that of the neighbouring cell populations. Screening by reverse transcription-polymerase chain reaction and in situ hybridization identified four genes (WIF1, PTGDS, ThPO and UCKL1) that are upregulated only in the organizer region when it becomes a stem zone and remain expressed there during axial elongation. In experiments specifically labelling the resident cells of the mature organizer, we show that only these cells express these genes. These findings molecularly define the organizer as a stem zone and offer a key to understanding how this zone is set up, the molecular control of its cells' behaviour and the evolution of axial growth zones.

Vacuum diffusion bonding of TC4 titanium alloy to T2 copper with VCrNi1.8 eutectic medium entropy alloy interlayer

A new eutectic medium entropy alloy VCrNi1.8 was designed for vacuum diffusion bonding TC4 titanium alloy (TC4) with T2 copper (T2). The influence of welding parameters on the microstructure and shear strength of joints was investigated. β-Ti/Ti3Ni/Ti3AlNi/Ti2Ni/TiNi/TiNi(V, Cr)2/BCC + FCC/Ni(V, Cr)2/Cu phases existed in sequence in the TC4/VCrNi1.8/T2 joint. The crystallographic orientations of Ti3AlNi, Ti2Ni, TiNi and TiNi(V, Cr)2 phases were (200), (020), (011) and (012), respectively. The zone axis of Ti3AlNi, Ti2Ni, TiNi and TiNi(V, Cr)2 phases was correspondingly [002¯], [202], [100] and [4¯00]. The maximum shear strength of joint made at 880 °C for 90 min reached 214 MPa. The growth activation energy of diffusion zones I and II on TC4/VCrNi1.8 side was 230 kJ/mol and 246 kJ/mol, respectively. The interplanar spacing of (200), (020), (011) and (012) was d(200) = 0.656 nm, d(020) = 0.375 nm, d(011) = 0.556 nm and d(012) = 0.225 nm, respectively. The crystal face mismatch of Ti3AlNi/Ti2Ni, Ti2Ni/TiNi and TiNi/TiNi(V, Cr)2 interface was calculated to be 54.5%, 58.3% and 84.8%, respectively, revealing non-coherent with high strain energy. When the bonding temperature increased and holding time prolonged, the joint fractured along the TC4/VCrNi1.8 interface. The fracture morphology of joint presented cleavage fracture characteristics. The average diffusion coefficient of Cu in VCrNi1.8 interlayer at 840 °C, 860 °C, 880 °C, and 900 °C was 0.9 × 10−15 m2/s, 1.2 × 10−15 m2/s,1.6 × 10−15 m2/s, and 2.5 × 10−15 m2/s, respectively.

Timing of hydrocarbon charge in the Axial Zone of the Eastern Cordillera, Colombia

The petroleum potential of onshore basins in Colombia has been partly controlled by the Andean Orogeny since the end of the Cretaceous. Its Axial Zone has at least one understudied active petroleum system with a rather low petroleum potential and few commercial medium to heavy oil accumulations, raising questions about how the Andean deformation influenced the petroleum system and the possible undiscovered accumulations. We examine the timing of this petroleum system in the Axial Zone through oil–source correlations and two 2D petroleum system models across the Boyacá and Soápaga faults based on cross-sections. Modelling reveals the direct control of deformation on generation–accumulation in the Axial Zone, where the Lower Cretaceous source rocks, due to high heat flows during the synrift phase, started generation so early (100 to 60 Ma) that no reservoirs or traps were yet available to allow hydrocarbon entrapment and accumulation. Equally, for the younger Upper Cretaceous source rocks, the tectonic inversion of the basin between 33 and 23 Ma along the Boyacá and Soápaga faults interrupted burial and the maturation in most parts of the basin, leaving only local pods of active source rocks where maturation continues today due to the tectonic overburden along the footwall of the Soápaga Fault. The latter is thus the major kitchen, contributing more than 50% of the liquid hydrocarbons trapped mainly in Upper Cretaceous and Paleocene sandstones. Hydrocarbons migrate upwards where biodegradation and water washing occurred in the near-surface, giving rise to the many tar sand occurrences in the Eocene sandstones.

Geological and hydrogeological drivers of seismic deformation in L’Aquila, Italy: insights from InSAR analysis

Historical and recent earthquakes have struck the city of L'Aquila, located in the axial zone of the Central Apennines, Italy, causing severe damage to the historic centre. Recent studies have shown that higher intensity of damage to buildings in L’Aquila downtown, both in the case of the 2009 earthquake (Mw: 6.29) and the 1703 earthquake (Mw: 6.7), is associated with higher post-seismic subsidence rates, detected through A-DInSAR maps, in the time range 2010–2021. This finding suggests the existence of geological factors that drive deformation (and building damage). The availability of long time series of InSAR data acquired from the Cosmo-SkyMed and Sentinel-1 missions, has enabled us to analyze the relationships between ground deformations and geological, hydrogeological, and geomorphological factors that may affect them. The correlation analysis between predisposing factors and SAR deformation has highlighted an increase in subsidence strongly conditioned by the outcropping lithology, showing how compositional variations within lithology can significantly influence ground deformations. Furthermore, hydrogeology has been recognized as playing an important role in determining deformation processes: the water table depth locally influences long-term subsidence, while seasonal fluctuations in the water table may be responsible for secondary areal variations in ground deformations.

A simple protocol for determining the zone axis direction from selected-area electron diffraction spot patterns of cubic materials.

Using the well known Rn ratio method, a protocol has been elaborated for determining the lattice direction for the 15 most common cubic zone axis spot patterns. The method makes use of the lengths of the three shortest reciprocal-lattice vectors in each pattern and the angles between them. No prior pattern calibration is required for the method to work, as the Rn ratio method is based entirely on geometric relationships. In the first step the pattern is assigned to one of three possible pattern types according to the angles that are measured between the three reciprocal-lattice vectors. The lattice direction [uvw] and possible Bravais type(s) and Laue indices of the corresponding reflections can then be determined by using lookup tables. In addition to determining the lattice direction, this simple geometric analysis allows one to distinguish between the P, I and F Bravais lattices for spot patterns aligned along [013], [112], [114] and [233]. Moreover, the F lattice can always be uniquely identified from the [011] and [123] patterns.

Oil families in the eastern cordillera and llanos basin, Colombia: A comprehensive characterization using advanced geochemical technologies

Three major age-related oil families, clustered into seven groups, were identified in the Llanos basin based on advanced geochemical technologies that unveiled complex mixtures throughout the basin. The analyses included the conventional whole oil and biomarker analysis and the more refined and advanced GC-MS/MS analysis. The latter provided for terrestrial diterpane-based age-specific arrays that discriminated between Cretaceous and Cenozoic floral types. The analysis of asphaltene hydrous pyrolysates revealed the initial charges to the reservoirs, often of early maturity, but also strongly biodegraded and overprinted by fresh oil charges. Extensive analysis on diamondoids allowed the characterization of the late maturity charges, differentiation between mixed and singly-sourced oils and the ability to tie together earlier with later generated oil components of oil mixtures. Oils from Family A are the most widespread in the basin, found in the southern Llanos and in the Foothills and are derived from Lower Cretaceous to Cenomanian marine shale with a terrigenous input. Within Family B, of Upper Cretaceous age, two main source facies were identified, one with a siliciclastic marine input, corresponding to Groups 4 and 5. They have the highest concentrations of the C25 highly branched isoprenoid (HBI) and occur in the Northern and Eastern Llanos and in the Axial Zone of the Eastern Cordillera. The other facies has a more calcareous aspect, identified mainly in the Southern Llanos designated as Groups 2 and 3. Family C, of Cenozoic age, is restricted to the Foothills and two oil Groups were distinguished: Group 6 as the only endmember of a terrigenous Cenozoic facies, identified in Oil 7, and Group 7 shows a Cenozoic terrigenous facies and varying degrees of mixing with a marine Cretaceous input. These families are mixed in a variety of ways, having mixtures from different facies, while others show multiple charges from the same facies.

Gamma-ray irradiation effect on planar defect evolution of lattice-matched InGaAsN/GaAs/Ge grown by MOVPE

This study explores structural changes in lattice-matched InGaAsN/GaAs/Ge films grown by MOVPE under gamma-ray irradiation. Exposure to a 60Co gamma rays at doses ranging from 0 to 2.0 MGy improved crystal uniformity by increasing surface grain size, reducing roughness from 8.328 nm to 3.512 nm. Planar defects in the GaAs layer traversed the InGaAsN layer, causing interface roughness. Electron diffraction patterns along the [110]-zone axis showed uniform alloy composition. TEM images revealed line contrasts at the GaAs/Ge interface extending into the InGaAsN layer, with boundary-like defects parallel to the growth direction. Additionally, (002) and (002‾) reflections, along with {111} planes, indicated planar defects, possibly antiphase boundaries. AFM and FESEM confirmed submicron-sized domains, characteristic of antiphase boundaries, in the InGaAsN film.

Geologically constrained geometry inversion and null-space navigation to explore alternative geological scenarios: a case study in the Western Pyrenees

SUMMARY Reducing the gap between geophysical inversion and geological interpretation can be achieved by integrating geological modelling into geophysical inversion. For this, we use a generalized, iterative level-set gravity inversion scheme in which geological units are deformed automatically. During the inversion process, a regularization term is defined using automated geological modelling to account for geological data and principles. This provides model-dependent geological constraints and encourages geological realism throughout inversion. To alleviate the dependence on the starting model and consider the possibility of features unseen by direct observations, an automated geophysical data-driven method is proposed to insert new rock units in the model. Uncertainty quantification is achieved through the null-space shuttle algorithm, which is used to generate a series of alternative models that are consistent with geophysical data. This methodology is applied to assess the uncertainties of a pre-existing 3-D crustal-scale geological model of the Western Pyrenean orogeny (France, Spain). The area is characterized by a positive gravity anomaly generally attributed to the presence of a shallow mantle body. The impact of variations in shape and density of key crustal and mantle features is investigated. Different scenarios are explored in 3-D space to produce a range of viable, relatively simple crustal-scale models of the area. This application demonstrates the capability and potential of this approach to evaluate alternative interpretations of geophysical data. The results show the plausibility of scenarios with a shorter subducted Iberian lower crust and a denser Axial Zone than in the pre-existing model.

Stratigraphy and Basin Analysis of the West Rand Group, Witwatersrand Supergroup

Abstract The Mesoarchaean West Rand Group displays a layer-cake stratigraphy with lithostratigraphic units correlatable on a basin-wide scale. The ~5 km-thick succession consists of fluvial braidplain and shelf deposits, which range from shallow inner shelf marine orthoquartzites, outer shelf argillites to starved shelf iron-formations. Minor diamictites are of debris flow origin and are possibly related to glacial activity. Three major sequences are present: Sequence I (Hospital Hill Subgroup) is bounded by an angular unconformity at the base of the Orange Grove Formation and a low-angle unconformity at the base of the Promise diamictite. Sequence II (Government Subgroup) extends from the base of the Promise diamictite to a well-defined low-angle unconformity at the base of the Koedoeslaagte Formation. Sequence III (Jeppestown Subgroup) comprises the succession between the Koedoeslaagte Formation and the Maraisburg Formation, up to the low-angle unconformity at the base of the Main Reef. Sequence I was deposited during a period of highstand of sea-level, Sequence II during a period of relative lowstand, and Sequence III during a period of relative highstand coupled with high rates of sediment supply. Isopach, depofacies and palaeocurrent analyses indicate that strata in the western to northwestern parts of the basin were deposited under more proximal sedimentary conditions compared to those in the central or southeastern parts of the basin. There is little relationship between the present outline of the basin and the distribution of depofacies or isopachs of sequences, and it is therefore concluded that the original sedimentary basin was significantly larger in areal extent. Depofacies and thickness distribution, as well as synsedimentary deformation of strata, indicate that the basin was most probably of flexural tectonic origin. These findings strongly support deposition in a wide, shallow, and rather stationary foreland basin, with an axial zone towards the west/northwest and a low amplitude peripheral bulge to the east/southeast. Such shallow foreland basins, with abundant sediment bypassing, are thought to be associated with windward-facing orogenic fronts. High rates of erosion along such fold-thrust belts lead to ineffective loading and advancement of the orogenic front, as well as an oversupply of sediment.

Chronostratigraphy and tectono‐sedimentary history of the Eastern South Pyrenean foreland basin (Ripoll Syncline, North‐East Spain)

AbstractThis paper contributes to an understanding of the tectono‐sedimentary evolution of the South Pyrenean foreland system by reviewing the chronostratigraphic framework of the basin infill in its eastern sector. Six sections are analysed and cross‐correlated to build a 6.5 km thick composite magnetostratigraphy that represents the complete record of the Cadí Nappe in the Ripoll Syncline. New and previous magnetostratigraphic sections are integrated with available biostratigraphy to provide a new age calibration of the sedimentary succession of the Cadí Nappe, encompassing from Palaeocene to Middle Lutetian age. The proposed correlation with the Geomagnetic Polarity Time Scale aims at best reconcile magnetostratigraphic data with the regional biochronology built on the marine Shallow Benthic Zonation (SBZ biozones), the continental mammalian biochronology (MP levels) and the newly collected charophyte data. A subsidence analysis was performed on the calibrated composite succession, resulting in two well‐defined intervals bounded by a hiatus. A Palaeocene to Early Eocene interval with low (11–21 cm/kyr) total subsidence rates, and an Early to Middle Eocene interval, characterised by high (70–75 cm/kyr) total subsidence rates. The detailed trends in both subsidence and sedimentation mark the development and evolution of the foreland depozones, from distal foreland depozones to foredeep and wedge‐top depozones, relative to the emplacement of the Pedraforca Nappe and Cadí Thrust Nappe. The most pronounced sedimentary shift in the Cadí Nappe occurred at 49 Ma, with the rapid drowning of the carbonate platforms and its transition into talus and deep basinal environments. Carbonate platforms collapsed and resedimented on the talus of the elongated trough, newly formed parallel to the orogenic front. This marked the onset of tectonic subsidence triggered by the submarine emplacement of the Lower Pedraforca Nappe. The emersion of the orogenic wedge drove the entry of siliciclastics, lagged by 1 Myr, into the Ripoll Trough. The foredeep filled rapidly (5.5 km thickness in less than 7 Myr) compared to other South Pyrenean regions, favoured by its semi‐enclosed palaeogeography. The emplacement of the Vallfogona Thrust as early as the Middle Lutetian (43 Ma) brought the Cadi Nappe into a wedge‐top setting. However, the Ripoll growth syncline continued acting as a temporary sink for alluvial sedimentation while a foredeep developed further south in the autochthonous Ebro Basin. The flexural response of the Iberian plate to the tectonic thickening of the Axial Zone counterbalanced for a period the local uplift of the Cadi Nappe, providing accommodation space for the top sediments filling the Ripoll Syncline.

Synthesis and in-depth structure determination of a novel metastable high-pressure CrTe3 phase

This study reports the synthesis and crystal structure determination of a novel CrTe3 phase using various experimental and theoretical methods. The average stoichiometry and local phase separation of this quenched high-pressure phase were characterized by ex situ synchrotron powder X-ray diffraction and total scattering. Several structural models were obtained using simulated annealing, but all suffered from an imperfect Rietveld refinement, especially at higher diffraction angles. Finally, a novel stoichiometrically correct crystal structure model was proposed on the basis of electron diffraction data and refined against powder diffraction data using the Rietveld method. Scanning electron microscopy–energy-dispersive X-ray spectrometry (EDX) measurements verified the targeted 1:3 (Cr:Te) average stoichiometry for the starting compound and for the quenched high-pressure phase within experimental errors. Scanning transmission electron microscopy (STEM)–EDX was used to examine minute variations of the Cr-to-Te ratio at the nanoscale. Precession electron diffraction (PED) experiments were applied for the nanoscale structure analysis of the quenched high-pressure phase. The proposed monoclinic model from PED experiments provided an improved fit to the X-ray patterns, especially after introducing atomic anisotropic displacement parameters and partial occupancy of Cr atoms. Atomic resolution STEM and simulations were conducted to identify variations in the Cr-atom site-occupancy factor. No significant variations were observed experimentally for several zone axes. The magnetic properties of the novel CrTe3 phase were investigated through temperature- and field-dependent magnetization measurements. In order to understand these properties, auxiliary theoretical investigations have been performed by first-principles electronic structure calculations and Monte Carlo simulations. The obtained results allow the observed magnetization behavior to be interpreted as the consequence of competition between the applied magnetic field and the Cr–Cr exchange interactions, leading to a decrease of the magnetization towards T = 0 K typical for antiferromagnetic systems, as well as a field-induced enhanced magnetization around the critical temperature due to the high magnetic susceptibility in this region.

Comment on , Lithos 456-457, 107325, Large silicic magma chambers at the Moho depth characterize the multi-level plumbing system of back-arc spreading ridges

An article (Gennaro et al., 2023, 456–457, 107325) recently published in Lithos proposes a model for the transcrustal magmatic plumbing system at the Marsili Seamount, a massive and still active volcanic centre at the Southern Tyrrhenian back-arc spreading ridge. Their model is based on a combination of geophysical and petrochemical data, the former confined to the axial zone of the Marsili volcano while the latter mostly refer to literature data dealing with samples collected from various sectors of the volcano. This comment questions the rationality of the proposed model, documenting that it is poorly constrained and, at places, incorrect.

Third harmonic generation in monoclinic 2D KNbO3 with high power endurance

Two-dimensional (2D) KNbO3 is prepared by topotactic transition from 2D KNbO2 at 530 °C in air, which has a single spontaneous polarization (Ps) direction along the [101¯]pc zone axis. The strong Ps anisotropy leads to a negligible second harmonic generation of 2D KNbO3 with laser vertically incident on the sample. However, a strong third harmonic generation is observed. The effective third-order susceptibility of 2D KNbO3 with the order of ∼10−19 m2 V−2 is estimated by comparing it with the χeff(3) of graphene. The robust power tolerance of 2D KNbO3 endows it great potential in the application of high-power third harmonic generation 2D devices.

ZH3: Quadratic Zonal Harmonics

Spherical Harmonics (SH) have been used widely to represent lighting in games and film. While the quadratic (SH3) and higher order spherical harmonics represent irradiance well, they are expensive to store and evaluate, requiring 27 coefficients per sample. Linear SH (SH2), requiring only 12 coefficients, are sometimes used, but they do not represent irradiance signals accurately and can have challenges with negative reconstruction. We introduce a new representation (ZH3) that augments linear SH with just the zonal coefficient of quadratic SH, yielding significant visual improvement with just 15 coefficients, and discuss how solving for a luminance zonal axis can significantly improve reconstruction accuracy and reduce color artifacts. We also discuss how, rather than storing the ZH3 coefficients explicitly, we can hallucinate them from the linear SH, improving reconstruction accuracy over linear SH at minimal extra cost.

Characterization of Al2O3 coating of Nb fiber-reinforced TiAl composite

The Al2O3 coating was synthesized on surface of the Nb fiber via cathodic plasma electrolytic deposition (CPED) method. The microstructure and composition of the coating were elaborately analyzed. The results revealed that compact and uniform Al2O3 is fully contact with TiAl matrix and Nb fiber, which was composed of κ-Al2O3 and α-Al2O3 and successfully hold back the oxidation reactions at the juncture and refrain from formation of detrimental phases. Especially, three-dimensional characterization information can be obtained from two-dimensional converging beam electron diffraction (CBED) pattern, from which the crystal constants of Al2O3 can be obtained directly under only one applicable zone axis.

The East Variscan Shear Zone (EVSZ) and Its Regional Mylonitic Complex: A New Geodynamic Interpretation of the Variscan Axial Zone in Sardinia (Italy)?

Sardinia (Italy) represents one of the most comprehensive cross-sections of the Variscan orogen. The metamorphic and structural complexity characterizing its axial zone still presents many unresolved issues in the current state of knowledge. The data presented from the structural study of the entire axial zone of this area have allowed the authors to propose a subdivision into two new structural complexes. In particular, a younger complex is identified as the New Gneiss Complex, containing remnants of an older and higher-grade metamorphic complex defined as the Old Gneiss Complex. The structural and geometric relationships between the two complexes suggest the redefinition of the axial zone of Sardinia as part of the intracontinental East Variscan Shear Zone/medium-temperature Regional Mylonitic Complex. Comparable relationships are also highlighted in many other areas of the Variscan chain (e.g., Morocco, Corsica, Maures Massif, and Argentera Massif). Extending this new structural interpretation to other axial zones of the South European Variscan orogen could provide new hints for reconstructing the collision boundaries between Gondwana and Laurussia in the late Carboniferous to the early Permian periods.

Achieving Complete Human Gingival Fibroblast Collagen Coverage on Implant Abutments through Vacuum Ultraviolet (VUV) Photofunctionalization.

The formation of a biological seal between implant abutments and the surrounding soft tissue is a preventive strategy against peri-implantitis. The aim of this study is to test the hypothesis that surfaces of prosthetic implant abutments treated with vacuum ultraviolet (VUV) light enhance the growth and function of human gingival fibroblasts. Implant abutments were treated with 172 nm VUV light for one minute. Untreated abutments were subjected as controls. Their surface properties were characterized using SEM, contact angle measurements, and chemical composition analysis. Human gingival fibroblasts were cultured on both untreated and VUV-treated abutments to evaluate cell attachment, proliferation, distribution, and collagen production. Cell detachment assays were also performed under various mechanical and chemical stimuli. After VUV treatment, implant abutments demonstrated a notable transition from hydrophobic to hydrophilic wettability. Surface element analysis revealed a considerable reduction in surface carbon and increases in oxygen and titanium elements on the VUV-treated surfaces. On day 1 of culture, 3.9 times more fibroblasts attached on VUV-treated abutments than on untreated control abutments. Fibroblastic proliferation increased 1.9-3.1 times on VUV-treated abutments, along with a significant improvement in the distribution of populating cells. Collagen production on VUV-treated abutments increased by 1.5-1.7 times. While untreated abutment surfaces showed voids and limited spread of collagen deposition, dense and full coverage of collagen was observed on VUV-treated abutments, with a great contrast in the challenging axial surface zone. Cell retention against mechanical and chemical detaching stimuli was increased 11.3 and 4.3 times, respectively, by VUV treatment. Treatment of implant abutments with VUV light for one minute resulted in a reduction of surface carbon and a transformation of the surface from hydrophobic to hydrophilic. This led to enhanced attachment, proliferation, and retention of human gingival fibroblasts, along with nearly complete collagen coverage on implant abutments. These in vitro results indicate the promising potential of utilizing VUV photofunctionalized implant abutments to enhance soft tissue reaction and sealing mechanisms.

Multi-physical effects induced by spatiotemporal corrosion of T91 cladding in oxygen-controlled LBE environment

T91, a pivotal candidate material for cladding in lead-based fast reactors (LFRs), demonstrates considerable potential for corrosion resistance in liquid lead-bismuth eutectic (LBE) corrosion experiments. However, the multi-physics characteristics of T91 cladding corrosion in its operational environment remain unclear, posing an obstacle to its practical application. This study focuses on the spatiotemporal corrosion of T91 cladding in multi-physics coupling scenarios by means of COMMA (Cladding/Oxidation corrosion Multi-physics Modeling and Analysis code), in which, modules of cladding oxidation, cladding oxide removal, heat transfer, mechanical deformation, and fission gas release are integrated and collaboratively solved. The corrosion patterns of T91 cladding with different oxygen concentrations and the underlying multi-physics behavior of the corrosion processes under operational conditions simulating are summarized. For the lower oxygen concentration of 1.8e-9 wt% in LFRs, the results indicate a 0.2 m axial zone with base material exposed to LBE reveals the presence of the oxidation protection failure. An exacerbation of cladding heat transfer degradation is observed after oxygen concentration reaching the oxygen-dominant region, due to the enhanced temperature positive feedback of oxidation corrosion. For the high oxygen concentration of 1.4e-6 wt%, an axial offset of 0.24 m for the location of the minimum gap size is observed. This study identifies a trend of the reduction thickness of cladding that first decreasing and then increasing with an elevated oxygen concentration, attributed to a transition in corrosion patterns. The temperature and mechanical analyses indicate that the optimal oxygen concentration for corrosion inhibition and fuel safety is located around the critical oxygen-dominant concentration.

Particle morphology characterization in an over-aged Al-Cu-Mg-Si alloy using TEM

A quantitative analysis of particle morphologies in a heterophase Al-Cu-Mg-Si alloy after over-aging has been performed using conventional transmission electron microscopy (TEM) imaging in dark- and bright-field modes. An appropriate analytical procedure has been suggested separating {100}Al plate- and 〈100〉Al rod-shaped particles using TEM images taken along 〈100〉Al and 〈110〉Al zone axes. The obtained statistical particle morphology parameters were verified by macroscopic strength contribution calculations.