Continued Deposition Research Articles

Flow analysis of the polymer spreading during extrusion additive manufacturing

The spreading of molten polymer between the moving printing head and the substrate in extrusion additive manufacturing is studied. Finite element computation and an analytical model have been used. The hypotheses of the analytical model are qualitatively justified by the results of the numerical computation. The analytical calculation is a powerful tool to rapidly evaluate the relationships between processing parameters (extrusion rate, printing head velocity, gap between the printing head and the substrate) and some characteristics of the deposition (dimensions of the deposited filament, pressure at the printing head nozzle, separating force between substrate and printing head). An isothermal hypothesis is discussed. The viscous non-Newtonian behavior is accounted for through an approximate shear thinning power law model. A printing processing window is defined following several requirements: a continuous deposit, without spreading in front of the printing head, maximum and minimum spreading pressures, an upper-limit for the separating force between head and substrate.

Room-temperature, atmospheric-pressure microsputtering of dense, electrically conductive, sub-100 nm gold films

In this study, we investigate the effects of deposition parameters (i.e. gas flow rates, bias voltages, and nozzle-to-substrate separation) on the microstructure of <100 nm thick gold deposits made with a room-temperature, atmospheric-pressure, ion-drag microsputterer. Without resorting to the use of vacuum or substrate heating, optimization of the printing process yields dense, continuous deposits (96.5% coverage) with low electrical resistivity (45 μΩ cm). Using statistical analysis, we developed a simple model that provides insight into the dynamics of such a printing method; based on this model, we identify electrostatic effects as the most important factor that influences the deposition process.

Hydrocarbon accumulation processes and mechanisms in Lower Jurassic tight sandstone reservoirs in the Kuqa subbasin, Tarim Basin, northwest China: A case study of the Dibei tight gas field

The Dibei gas field is a large tight gas field located in the Kuqa subbasin, Tarim Basin, northwestern China. The reservoir is within the Lower Jurassic Ahe Formation (J1a) and has porosity and permeability ranges of 2%–8% and 0.01–1 md, respectively. Two episodes of hydrocarbon charge are identified based on a detailed study of fluid-inclusion petrography and microthermometry, fluorescence spectroscopy characteristics, and the thermal maturity of both gas and light oil. Low-maturity oil as represented by hydrocarbon inclusions with yellow-green fluorescence entered the reservoir circa 23–12 Ma, whereas high-maturity hydrocarbons, as indicated by hydrocarbon inclusions with blue-white fluorescence, have charged the reservoir since 5 Ma. The hydrocarbon charge process combined with porosity evolution determined the present gas–water distribution characteristics in the Dibei gas field. Porosity in the J1a sandstone reservoir was relatively high during the first episode of hydrocarbon charge, which allowed oil to migrate upward and accumulate in structural highs under buoyancy. From 5 Ma to the present, the Dibei gas field experienced strong tectonic compression associated with intense thrust-fault reactivation, causing deformation and oil leakage from the reservoir. Continuous tight sand deposits along the slope areas, located far away from the active faults, became favorable accumulation sites for gas derived from the underlying Triassic source rocks. Hydrocarbon accumulation along the slope area in the Ahe Formation is dominantly controlled by equilibrium between hydrocarbon-generation pressure and capillary pressure.

Bullous Systemic Lupus Erythematosus and Membranous Lupus Nephritis in a Filipino Child

Bullous eruptions are rare cutaneous manifestations of systemic lupus erythematosus. We report a case of an 8-year old Filipino girl with vesiculobullous systemic lupus erythematosus (SLE) and membranous lupus nephritis on kidney biopsy who presented with clinical nephrotic features of generalized edema, proteinuria, hypoalbuminemia and hyperlipidemia. The 2012 Systemic Lupus International Collaborating Clinics (SLICC) classification criteria for SLE were met. Immunohistopathologic examination of the skin lesion revealed a sub-epidermal split with neutrophilic infiltrates along the dermo-epidermal junction, moderate perivascular, periadnexal and interstitial infiltrates composed of predominantly neutrophils with neutrophilic dusts, lymphocytes, plasma cells, rare eosinophils and increased dermal mucin. Direct immunofluorescence showed strong continuous linear IgG deposits along the basement membrane and weak linear IgM and IgA deposition along the basement membrane zone (BMZ). To our knowledge, this is the first report of vesiculobullous SLE in a Filipino child. This case is a rare form of cutaneous lupus in children. Bullous SLE (BSLE) should be considered in the differential diagnosis of children presenting with generalized bullous eruptions.

A Research of the Cretaceous-Paleogene Boundary in the Pingyi Basin, Shandong Province

The Bianqiao Formation (in the Pingyi Basin, Shandong Province, China) is a typical set of continuous lacustrine carbonate deposits during the Cretaceous-Paleogene period, which is considered as an ideal stratigraphic unit for KPB research. This study is based on the borehole PYZK01, which is located at Tongjiazhuang village in Bianqiao Town of Pingyi country. According to biostratigraphy research, the Bianqiao Formtion establishes one charophyte assemblage: Porocharaanluensis-Charayuntaishanensis var. acuta-Turbocharaspecialis, and one sporopollen assemblage: Deltoidosporaadriensis-Rugubivesiculites- Schizaeoisporites. This result indicates that the stratigraphic age during 0 - 12.25 m is the Paleogene, 37.8 m - 60 m is the Late Cretaceous, and 12.25 - 37.8 m is a transition stage from the Late Cretaceous to the Paleocene. By geochemical study, it was established carbon and oxygen isotopic strata in the drill. Through the magnetostratigraphy research, we find eight positive polarity zones and seven reversed polarity zones, build the magnetic polarity sequences of the borehole, and propose a contrast scheme with the international standard magnetic polarity time column. After comprehensive discussion, it is preliminarily believed that the Cretaceous-Paleogene boundary is located at the depth of 31.98 m in PYZK01, namely, in the first section of the Bianqiao Fm.

Advances in the Study of the Non-Marine Ostracods in Luanping Basin, Northern Hebei (North China): A Preliminary Result

The Luanping Basin of northern Hebei, North China, is well known for its continuous nonmarine Lower Cretaceous deposits and the preservation of the Jehol Biota. However, there are still some controversies about the stratigraphic correlation in these regions. Here we report some advances on the study of the nonmarine ostracods of Luanping, focusing on its biostratigraphical utility. Preliminary results indicate that the nonmarine ostracods from Luanping Basin consist of 17 genera and around 44 species. The ostracod assemblages of the Dabeigou, Dadianzi and Xiguayuan formations of this Basin can be assigned to the Luanpingella-Ocrocypris-Eoparacypris (Late Valanginian-Early Hauterivian age), Cypridea-Timiriasevia-Daurina (Late Huaterivian-Barremian age) and Cypridea-Limnocypridea-Lycopterocypris (Aptian stage) zones, respectively. This temporary framework can be served as a stratigraphic correlation tool in northern Hebei, as well as contributed to a better understanding of the evolution of the Jehol Biota.

Late Neogene aridification and wind patterns in the Asian interior: Insight from the grain-size of eolian deposits in Altun Shan, northern Tibetan Plateau

A well-preserved and continuous Neogene red clay deposit, the Caihonggou section, was recently discovered in the eastern Xorkol Basin, in the Altun Shan area at the northern margin of the Tibetan Plateau. We report detailed grain-size analyses for the Caihonggou red clay and also for the Shilou red clay section of the Chinese Loess Plateau in east-central China. Although the grain sizes are similar and can be modeled as two-component mixtures, the temporal variation of grain size and the proportions of grain-size components are very different between the Caihonggou and Shilou sections, indicating that their transportation and deposition processes and/or source areas were completely different. The fine component of the Caihonggou red clay was transported by high-level westerlies, whereas the coarser particles were carried by lower-level westerlies coming from the Taklimakan Desert, as indicated also by previous detrital zircon provenance analysis. A range of grain-size parameters for the Caihonggou section indicate that since about 8 Ma, and particularly between 8 and 6 Ma, the westerly winds strengthened, and the aridity of the Asian interior increased.

Discoidin Domain Receptor 2 Signaling Regulates Fibroblast Apoptosis through PDK1/Akt.

Progressive fibrosis is a complication of many chronic diseases, and collectively, organ fibrosis is the leading cause of death in the United States. Fibrosis is characterized by accumulation of activated fibroblasts and excessive deposition of extracellular matrix proteins, especially type I collagen. Extensive research has supported a role for matrix signaling in propagating fibrosis, but type I collagen itself is often considered an end product of fibrosis rather than an important regulator of continued collagen deposition. Type I collagen can activate several cell surface receptors, including α2β1 integrin and discoidin domain receptor 2 (DDR2). We have previously shown that mice deficient in type I collagen have reduced activation of DDR2 and reduced accumulation of activated myofibroblasts. In the present study, we found that DDR2-null mice are protected from fibrosis. Surprisingly, DDR2-null fibroblasts have a normal and possibly exaggerated activation response to transforming growth factor-β and do not have diminished proliferation compared with wild-type fibroblasts. DDR2-null fibroblasts are significantly more prone to apoptosis, in vitro and in vivo, than wild-type fibroblasts, supporting a paradigm in which fibroblast resistance to apoptosis is critical for progression of fibrosis. We have identified a novel molecular mechanism by which DDR2 can promote the activation of a PDK1 (3-phosphoinositide dependent protein kinase-1)/Akt survival pathway, and we have found that inhibition of PDK1 can augment fibroblast apoptosis. Furthermore, our studies demonstrate that DDR2 expression is heavily skewed to mesenchymal cells compared with epithelial cells and that idiopathic pulmonary fibrosis cells and tissue demonstrate increased activation of DDR2 and PDK1. Collectively, these findings identify a promising target for fibrosis therapy.

Formation of an Electrode Deposit under Galvanostatic Conditions

The laws of formation of a continuous deposit layer at a given direct current are considered. Equations are analyzed to calculate the time dependences of overpotential for instantaneous nucleation with kinetic or diffusion control of new-phase growth. The calculated dependences are compared with the experimental ones obtained for silicon electrodeposition from a fluoride–chloride melt.

In Situ stress Measurements during Strained-Layer Electrodeposition

Enhanced catalytic activity has been demonstrated in elastically strained thin films, pseudomorphically grown on substrates with an appropriate lattice mismatch. The enhancement in catalytic activity is typically attributed to both electronic interactions and the epitaxial mismatch strain in the overlayer. The magnitude of the strain is often estimated from lattice-constant measurements using x-ray diffraction. An additional probe gaining popularity in electrochemistry involves the measurement of surface and growth stress using cantilever curvature. Cantilever curvature offers a nice complement to the direct strain measurementand can provide an in situ measurement while the strained layer is being formed. This talk will focus on the biaxial growth stress that develops during the self-terminated electrodeposition of ultrathin Pt films onto a variety of cantilever substrates that introduce different levels of misfit strain into the Pt. The cantilever was a borosilicate glass strip measuring 60 mm × 3 mm × 0.108 mm and was metallized on one side by electron beam evaporation, resulting in substrates with strong (111) crystallographic orientation. The electrolyte was 0.5 mol/L NaCl containing 3 mmol/L K2PtCl4. Deposition consisted of stepping the potential from the open circuit potential (~ -0.1V vs SSE) down to -1.2V for 10s and then back to -0.1V for another 30s, following the procedure established by Liu et al.1Figure 1 shows the stress response for Au, Pt and Ir substrates. Pt grown on Au exhibits considerable tensile stress, which is consistent with the +3.9% lattice mismatch between Au and Pt. In contrast, Pt deposition onto a Pt cantilever deposits homoepitaxially as an unstrained continuation of the substrate. The slight increase in stress with continued deposition is likely microstructural. Pt grown on Ir, with its -2.1% lattice misfit, initially exhibits compressive stress, before leveling off and turning tensile, similar to the growth of Pt on Pt. Although it is tempting to focus on lattice misfit as the primary source of stress, one must consider other contributions, such as step line tension associated with the growth of small islands, possible intermixing, and surface roughness. References Y. Liu, D. Gokcen, U. Bertocci and T. P. Moffat, Science 338, 1327 (2012). Figure 1

Palaeoecological evolution of a spring-fed fen in Pawłów (eastern Poland)

A continuous record of sedimentation in spring-fed fens makes them suitable for detailed palaeoenvironmental studies. A newly investigated cupola spring-fed fen (Pawłów site), located in the Lublin chalkland, eastern Poland, was the object of our study. This special karst region is characterised by the occurrence of Upper Cretaceous carbonate rocks in the substratum. Sedimentological observations indicated strong variability of biogenic-carbonate series in the deposits (=peat-tufa rhythmite), reflects changes of accumulation conditions (oxidising versus reducing), resulting from alternate occurrence of warmer and cooler periods. Difficulties in pollen analysis due to oxidising conditions necessitate a multidisciplinary approach for palaeoenvironmental reconstruction. We used a multidisciplinary approach (sedimentological, palaeobotanical, geochemical analyses and radiocarbon dating) to determine the main evolutionary stages of this unique fen ecosystem and to discuss the role of local or/and regional factors in its development. Pollen and plant macrofossil analyses, supported by radiocarbon dating, proved that the bottom part of the cores represents the Late Glacial–Early Holocene stages of the fen development. A comparative analysis of palaeoenvironmental data showed close resemblance between the Pawłów fen and the earlier studied fens in eastern Poland and Central-Eastern Europe, and the connection between their development and supraregional hydrological-climatic factors. The results indicated also the influence of the morphological position of such a type of ecosystem on the development of a continuous deposit succession. The occurrence of a river valley in close proximity of the Pawłów site resulted in the lack of tufa deposits from the Atlantic period, because of an erosional phase in the river valley.

In-Situ Measurements of Stress during Electrodeposition of Copper Nanofilms: Surface and Grain-Boundary Migration of Atoms and the Effect of Chloride Ions

Electrodeposited metal films are often in a state of stress and this has been the subject of extensive experimental investigation and theoretical analysis1-4. We have been measuring stress development in situ during electrodeposition and correlating the results with in-situ AFM imaging during electrodeposition under similar conditions. In this paper we present results on the early stages of copper deposition from acidic CuSO4 electrolytes with and without chloride as an additive. To examine the effect of growth rate, sequential galvanostatic depositions were carried out (after an initial potentiostatic deposition of a thin layer of copper) over a relatively large range of growth rates (from 0.22 nm s-1 to 6.9 nm s-1) in additive-free electrolyte. At low growth rates, steady state stress was compressive. As growth rate was increased, the stress became less compressive and eventually became tensile. Crossover from compressive to tensile stress occurred at a growth rate of ~1 nm s-1. Both in-situ AFM imaging during deposition and ex-situ SEM imaging were used to characterise the evolution of grain size during the sequence of galvanostatic depositions used in the stress measurements. In general, grain size increased with continued deposition but eventually reached a constant value. Simulations based on Chason’s kinetic model3 gave a good fit of our experimental stress measurements in the region of constant grain size (~970 nm). The parameters from this fit were then used to model the steady state stress as a function growth rate and grain size. The values predicted by the model are plotted against the values from the experimental measurements in Figure 1. It can be seen that there is good agreement between model and experiment. The effect of added chloride in the electrolyte was also investigated. Even at low concentrations (< 1 ppm), the presence of chloride considerably reduced the tensile stress. Chloride-free and chloride-containing electrolytes also showed very different behaviours after interruption of electrodeposition. In chloride-free electrolyte, the tensile steady-state stress observed during deposition changed to compressive stress on interruption of the deposition. However, in chloride-containing electrolyte, the stress became even more tensile on interruption of deposition. Our experimental results on the change from one type of behaviour to the other as the chloride concentration was increased will be described and possible mechanisms will be discussed. References O.E. Kongstein, U. Bertoci and G.R. Stafford, J. Electrochem. Soc. 152, C116 (2005).S. Ahmed, T.T. Ahmed, M. O'Grady, S. Nakahara and D.N. Buckley, J. Applied Physics 103, (2008).E. Chason, Thin Solid Films 526, 1 (2012).E. Chason, A. Engwall, F. Pei, M. Lafouresse, U. Bertocci, G. Stafford, J.A. Murphy, C. Lenihan and D.N. Buckley, J. Electrochem. Soc. 160, D3285 (2013) Figure 1

Model for polluted insulator flashover under AC or DC voltage

The aim of this paper is to elaborate a model describing the different phases of flashover of high voltage insulators with continuous or discontinuous pollution deposits, in AC or DC. This model uses an equivalent electrical circuit. It consists of three sub-algorithms: (1) The first one is a preliminary algorithm enabling the quantification of the electrical equivalent circuit parameters based on analytical and semi-analytical formulations; (2) the second one is relative to the steady state of discharge (static sub-model), at the beginning of flashover; and (3) the third one describes the unstable mode (dynamic sub-model). The whole algorithm describes the evolution of the discharge up to flashover. It enables to determine the different parameters characterizing the discharge such as the current, length, radius, propagation velocity, linear resistance and temperature. The simulated values are found in a good agreement with the experimental ones.

Ostracods of the non-marine Lower Cretaceous Dabeigou Formation at Yushuxia (Luanping basin, North China): Implications for the early Jehol Biota age

The Dabeigou Formation in the Luanping basin in northern China is well known for its continuous non-marine Lower Cretaceous deposits and the preservation of the early Jehol Biota, including abundant ostracods. However, the age of the Dabeigou Formation is still disputed. Here, we present a detailed lithostratigraphic analysis and ostracod biostratigraphy of the newly exposed Yushuxia section of the Luanping basin. At this locality, the Dabeigou Formation can be subdivided into 46 layers, which is mainly composed of grey to dark grey fine clastics of semi-deep lake face. Ostracod analysis on samples from the Dabeigou Formation revealed 14 species of nine genera. Biostratigraphically, the ostracods of the Dabeigou Formation belong to the Luanpingella-Torinina-Eoparacypris Zone. Most of the species range from the latest Jurassic to the earliest Cretaceous. However, some species show a closer relation with ostracods from the upper Lower Cretaceous Dadianzi Formation (upper Hauterivian to Barremian), the Yixian Formation (lower Aptian) of North China, and the Purbeck–Wealden Group (uppermost Tithonian to lowermost Aptian) of Britain. Combined with the biostratigraphy of other fossils and the U-Pb age, it is suggested that the ostracod fauna of the Dabeigou Formation and the origin of early Jehol Biota might be of Early Cretaceous age entirely.

Silurian deltaic progradation, Tassili n’Ajjer plateau, south-eastern Algeria: Sedimentology, ichnology and sequence stratigraphy

The economic potential for unconventional shale oil and gas production in the Silurian of the Berkine – Ghadames and Illizi basins (BGI) in south-eastern Algeria has been recently confirmed through exploration drilling. The aim of the present paper attempts a better understanding of the Intra-Tassilian depression within the entire Silurian of the Tassili n’Ajjer plateau. The continuous deposits of the Silurian are exposed at the southern margin of the prolific BGI basins, in the Tassili n’Ajjer plateau, offering the chance to understand the sedimentology, ichnology, and to present a detailed sequence stratigraphy framework for the region.The 410 m-thick clastic Silurian sedimentary strata are subdivided into three formations in the context of sequence stratigraphy, namely: (i) the Oued Imihrou Fm. (Llandoverian) overlain by (ii) the Atafaïtafa Fm. (late Llandoverian to Wenlockian), and (iii) the Oued Tifernine Fm. (late Wenlockian to Pridolian). These can be also distinguished across the entire investigated area and laterally traceable over kilometers. Clear cyclic stacking patterns are identified within the four studied sections showing progressively a general trend of thickening- and coarsening-upward, over a complete 2nd-order megasequence (SIL-1 MS). This transgressive-regressive succession suggests deltaic progradation, shallowing and basin infilling as evidenced by numerous diagnostic sedimentary features and trace fossils, largely from eastern-to western-Tassili plateau. Indeed, the wealth of outcrop data in the Silurian siliciclastic succession enables us to distinct thirteen facies (facies A-M), ranging from shallow-to marginal-marine facies, and in turn, grouped into six facies associations (FA1-FA6). The lowermost part of the succession, which is the most prolific sources of hydrocarbons in North Africa, consists of thick organic-rich graptolite-yielding black ‘hot’ shales and ‘lean’ shales with sparse bioturbation with small Thalassinoides belonging to the distal Cruziana ichnofacies. In contrast, the uppermost part of the Silurian deposits becomes progressively coarser and fluvial in response to the progradation of the North African Akakus deltaic system, during regional sea level fall and uplifting of the region. These progradational deposits exhibit well-preserved trace fossils with moderate to high degree of bioturbation, such as Skolithos or the so-called “Tigillites” pipe-rock, Cruziana isp., Rusophycus isp., Monocraterion isp., and Syringomorpha.The SIL-1 MS is bounded by a post-glacial latest Hirnantian unconformity on the basal (SB1), as confirmed by the moderately diverse early Silurian graptolite faunas, and by the Caledonian unconformity on the top (SB7). Each of the three formations of SIL-1 MS reveals two major 3rd-order progradational sequences, commonly delineated by discontinuity surfaces (in ascending order, SB1 to SB7), and in turn, these six sequences (i.e. Si-1 to Si-6) are subdivided into at least ten shorter-term cycles. The regional extent of each unconformity is directly linked to significant facies changes and to inflection points on the global sea level curve.

Translating the combination of gene therapy and tissue engineering for treating recessive dystrophic epidermolysis bullosa.

The combination of gene therapy and tissue engineering is one of the most promising strategies for the treatment of recessive dystrophic epidermolysis bullosa (RDEB). RDEB is a rare genetic disease characterised by mutations in the COL7A1 gene, encoding type VII collagen (COLVII), which forms anchoring fibrils at the dermal-epidermal junction of the skin. This disease causes severe blistering and only palliative treatments are offered. In this study, the base of a strategy combining gene therapy and a tissue-engineered skin substitute (TES), which would be suitable for the permanent closure of skin wounds, was set-up. As a high transduction efficiency into fibroblasts and/or keratinocytes seems to be a prerequisite for a robust and sustained correction of RDEB, different envelope pseudotyped retroviral vectors and the transduction enhancer EF-C were tested. When green fluorescent protein (GFP) was used as a reporter gene to evaluate the retroviral-mediated gene transfer, the fibroblast infection efficiency was 30 % higher with the Ampho pseudotyped vector as compared with the other pseudotypes. At least a 3.1-fold and a 1.3-fold increased transduction were obtained in fibroblasts and keratinocytes, respectively, with EF-C as compared with polybrene. A continuous and intense deposit of haemagglutinin (HA)-COLVII was observed at the dermal-epidermal junction of self-assembled TESs made of cells transduced with a HA-tagged COL7A1 vector. Furthermore, HA-tagged basal epidermal cells expressing keratin 19 were observed in TESs, suggesting stem cell transduction. This approach could be a valuable therapeutic option to further develop, in order to improve the long-term life quality of RDEB patients.

Timing and Distribution of Single‐Layered Ejecta Craters Imply Sporadic Preservation of Tropical Subsurface Ice on Mars

AbstractDetermining the evolution of tropical subsurface ice is a key component to understanding Mars's climate and geologic history. Study of an intriguing crater type on Mars—layered ejecta craters, which likely form by tapping subsurface ice—may provide constraints on this evolution. Layered ejecta craters have a continuous ejecta deposit with a fluidized‐flow appearance. Single‐layered ejecta (SLE) craters are the most common and dominate at tropical latitudes and therefore offer the best opportunity to derive new constraints on the temporal evolution of low‐latitude subsurface ice. We estimate model formation ages of 54 SLE craters with diameter (D) ≥ 5 km using the density of small, superposed craters with D &lt; 1 km on their continuous ejecta deposits. These model ages indicate that SLE craters have formed throughout the Amazonian and at a similar rate expected for all Martian craters. This suggests that tropical ice has remained at relatively shallow depths at least where these craters formed. In particular, the presence of equatorial SLE craters with D ~ 1 km indicates that ice could be preserved as shallow as ~100 m or less at those locations. Finally, there is a striking spatial mixing in an area of highlands near the equator of layered and radial (lunar‐like ballistic) ejecta craters; the latter form where there are insufficient concentrations of subsurface ice. This implies strong spatial heterogeneity in the concentration of tropical subsurface ice.

Investigation of Charon's Craters With Abrupt Terminus Ejecta, Comparisons With Other Icy Bodies, and Formation Implications

AbstractOn the moon and other airless bodies, ballistically emplaced ejecta transitions from a thinning, continuous inner deposit to become discontinuous beyond approximately one crater radius from the crater rim and can further break into discrete rays and secondary craters. In contrast, on Mars, ejecta often form continuous, distinct, and sometimes thick deposits that transition to a low ridge or escarpment that may be circular or lobate. The Martian ejecta type has been variously termed pancake, rampart, lobate, or layered, and in this work we refer to it as “abrupt termini” ejecta (ATE). Two main formation mechanisms have been proposed, one requiring interaction of the ejecta with the atmosphere and the other mobilization of near‐surface volatiles. ATE morphologies are also unambiguously seen on Ganymede, Europa, Dione, and Tethys, but they are not as common as on Mars. We have identified up to 38 craters on Charon that show signs of ATE, including possible distal ramparts and lobate margins. These ejecta show morphologic and morphometric similarities with other moons in the solar system, which are a subset of the properties observed on Mars. From comparison of these ejecta on Charon and other solar system bodies, we find the strongest support for subsurface volatile mobilization and ejecta fluidization as the main formation mechanism for the ATE, at least on airless, icy worlds. This conclusion comes from the bodies on which they are found, an apparent preference for certain terrains, and the observation that craters with ATE can be near to similarly sized craters that only have gradational ejecta.

The significance and timing of sheetflood vs braided channel deposition on lacustrine fan deltas, Junggar Basin, NW China

ABSTRACTThe fan-delta reservoir play has become an important exploration target within the Junggar Basin, especially in the Mabei area within the Mahu Sag, where a fan-delta oil and gas pool has been recently discovered. The sedimentary characteristics, distribution patterns and formation mechanisms of the fan-delta clastic bodies in Lower Triassic Baikouquan Formation (T1b) were studied using seismic, well log and core data accompanied by a flume tank experiment and a modern analogue depositional study. The T1b in the Mabei area is composed of a fan delta consisting of fan-delta plain (including debris flow deposits, sheetflood deposits, braided channel deposits, and floodplain deposits), fan-delta front (including subaqueous reworked sheetflood deposits and distal sheetflood deposits) and muddy lake deposits. The sheetflood deposits, characterised by moderately sorted conglomerates with brown matrix, form during the peak flooding. They are widespread and sheet-like, occupying the major portion of the fan-delta plain. The braided channel deposits are characterised by well-sorted and clast-supported conglomerates and pebbly sandstones, formed later during the falling flow stage. Owing to the decline in volume and velocity, and the formation of continuously braided fluid flow, the sediments of the flood period are reworked, generating the braided channels. Laterally, the braided channels occur as belts of clastic bodies surrounded by continuous sheetflood deposits. Vertically, the braided channels are interbedded between the sheetflood deposits. The subaqueous reworked sheetflood deposits are characterised by greyish-green, well-sorted and clast-supported conglomerates, whereas the distal sheetflood deposits are characterised by well-sorted sandstones, intercalated with mudstone. The subaqueous reworked sheetflood and distal sheetflood deposits are a distal partly subaqueous extension of the main sheetflood deposits, albeit reworked by basinal currents and waves. The distal sheetflood deposits form on distal fringes of the sheetfloods and are more thoroughly reworked by longshore and wave currents. The braided channel, subaqueous reworked sheetflood and distal sheetflood deposits can form high-porosity reservoirs. These findings challenge the common view and suggest that the channelised facies on the fans are not the main flood events; rather, the more extensive sheetfloods are the major flood events.

Clinical and Radiographic Outcomes of Traumatized Immature Permanent Necrotic Teeth after Revascularization/Revitalization Therapy

Introduction: Revascularization treatment is rapidly becoming an accepted treatment alternative for the management ofendodontic pathology in immature permanent teeth with necrotic dental pulps. However, the success and timing of clinical resolution of symptoms, and radiographic outcomes of interest, such as continued hard tissue deposition within theroot, are largely unknown.Methods: In this prospective cohort study, 20 teeth were treated with a standardized revascularization treatment protocol and monitored for clinical and radiographic changes for 1 year. Standardized radiographs were collected at regular intervals, and radiographic changes were quantified.Results: All 20 treated teeth survived during the 12- month follow-up period, and all 20 also met the clinical criteria forsuccess at 12 months. As a group, the treated teeth showed a statistically significant increase in radio- graphic root width andlength and a decrease in apical diameter, although the changes in many cases were quite small (such that the clinicalsignificance is unclear). The within-case percent change in apical diameter after 3 months was 16% and had increased to 79% by 12 months, with 55% (11/20) showing complete apical closure. The within-case percent change in root length averaged less than 1% at 3 months and increased to 5% at 12 months. The within-case percent change in root thickness averaged 3% at 3 months and 21% at 12 months. Conclusions: Although clinical success was highly predictable with this procedure, clinically meaningfulradiographic root thickening and length- ening are less predictable after 1-year of follow-up. Api- cal closure is the mostconsistentradiographic finding.(J Endod 2014;40:1946–1952).