AF Mode Research Articles

A New Emission Mode of PSR B1859+07

Previous studies have identified two emission modes in PSR B1859+07: a normal mode that has three prominent components in the average profile, with the trailing one being the brightest, and an anomalous mode (i.e., the A mode) where emissions seem to be shifted to an earlier phase. Within the normal mode, further analysis has revealed the presence of two submodes, i.e., the cW mode and cB mode, where the central component can appear either weak or bright. As for the anomalous mode, a new bright component emerges in the advanced phase while the bright trailing component in the normal mode disappears. New observations of PSR B1859+07 using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) have revealed the existence of a previously unknown emission mode, dubbed the Af mode. In this mode, all emission components seen in the normal and anomalous modes are detected. Notably, the mean polarization profiles of both the A and Af modes exhibit a jump in the orthogonal polarization angle modes in the bright leading component. The polarization angles for the central component in the original normal mode follow two distinct orthogonal polarization modes in the A and Af modes respectively. The polarization angles for the trailing component show almost the same but a small systematic shift in the A and Af modes, roughly following the values for the cW and cB modes. Those polarization features of this newly detected emission mode imply that the anomalous mode A of PSR B1859+07 is not a result of “phase shift” or “swooshes” of normal components, but simply a result of the varying intensities of different profile components. Additionally, subpulse drifting has been detected in the leading component of the Af mode.

Microstructure and mechanical properties of wire-powder hybrid additive manufacturing for high nitrogen steel

A novel wire-powder hybrid arc additive manufacturing (WPHAAM) was applied for melting zone nitridizing to avoid the deterioration effect caused by the loss of nitrogen in high nitrogen steel. A designed Cr-Mn-N wire with 0.79 wt% of nitrogen (HNS6) was used to build a high nitrogen wall body by introducing WPHAAM method. The influence of nitrogen content on solidification behavior, microstructure, and tensile properties were studied in the as-built conditions. With the increase of amount of feeding powder, the solidification mode of the deposited wall changes from primary ferrite with second-phase austenite (FA mode) to primary austenite with second-phase ferrite (AF mode), and the mechanical properties are enhanced. When the powder feeding rate reaches 0.33 g/min, the solidification changes to A mode, and the deposited metal is austenite. The ultimate tensile strength and elongation of the deposited metal are 1014 MPa and 50.8% respectively.

Energy Efficiency Maximization for Energy Harvesting Bidirectional Cooperative Sensor Networks with AF Mode

Energy Efficiency Maximization for Energy Harvesting Bidirectional Cooperative Sensor Networks with AF Mode

Microstructure and properties of Fe–Cr–Ni alloy coatings on T10 steel by laser cladding

In the present study, Fe–Cr–Ni alloy coatings were produced by laser cladding using the blending powder of Cr and Ni on the surface of T10 steel. The composition of phase and microstructure were analyzed by scanning electron microscope (SEM) and x-ray diffraction (XRD). The microhardness and corrosion resistance were investigated. The Fe–Cr–Ni cladding coatings composed of austenites and a few eutectic ferrites. And the content of eutectic ferrite in the grain boundary decreased with the decreasing Cr/Ni ratio of the blending powder. The Creq/Nieq ratio and the ferrite number (FN) of the coatings confirm that the solidification process was the AF mode for the Fe–Cr–Ni cladding coatings. The average microhardness value of Fe–Cr–Ni coatings was about 380HV0.2 and the Cr/Ni ratio of the blending powder was not an obvious effect. The corrosion resistance of Fe–Cr–Ni alloy coatings which was significantly superior to T10 steel decreased with the decreasing Cr/Ni ratio of the blending powder. This research exhibits that the Fe–Cr–Ni coatings and laser cladding processing have a potential engineering application value on hypereutectoid carbon steel.

Arc weldability of Incoloy 825 to AISI 321 stainless steel welds

Composition effect of Inconel 625, Incoloy 65 and ER347 fillers on microstructural evolution and solidification crack (SC) sensitivity of gas tungsten arc welded Incoloy 825 to AISI 321 SS was investigated. The structure of welds had been mostly austenitic, and solute segregation caused formation of eutectic-nature secondary phases in inter-dendritic/cellular spaces of three weld alloys. The dilution effect led to a transition from FA to AF mode of solidification in ER347 weld and decreased its ferrite content. Inconel 625 and ER347 welds had the highest and lowest resistance to SC during Longitudinal Varestraint Test, respectively. Fine dendritic structure of Inconel 625 weld resulted in easier strain accommodation and better weldability properties of this alloy. Severe cracking and high sensitivity of ER347 weld to SC were characterized because of low ferrite content and easier wettability of solidification grain boundaries due to formation of low-melting Nb and Ti-rich phases. Inconel 625 filler could play an effective role in establishing an appropriate bridge in terms of thermal expansion coefficient between dissimilar parent metals.

Characterization of microstructure of A508III/309L/308L weld and oxide films formed in deaerated high-temperature water

The microstructure of A508III/309L/308L weld clad and the properties of the oxide films formed in simulated pressurized water reactor primary water at 290 °C were characterized. The A508III heat-affected zone (HAZ) consisted primarily of a decarburization zone with ferrite near the fusion line and a following pearlite structure with fine grains. A high hardness region in the HAZ could be the result of C-enrichment. M23C6 and M7C3 precipitates were observed in element transition zone. 308L stainless steel (SS) containing ∼ 12% ferrites exhibited both ferritic-austenitic solidification mode (FA mode, δ→γ) and austenitic-ferritic solidification mode (AF mode, γ→δ), whereas 309L SS containing ∼ 9% ferrites exhibited only FA mode. The A508III surface oxide film was mainly Fe3O4 in deaerated high-temperature water. The coarse grain zone covered with few oxide particles was different from other types of film on the other region of HAZ and the bulk zone. More pitting appears on 309L SS after immersion in deaerated high-temperature water due to the dissolution of inclusions. SS surface oxide films consisted primarily of spinels. The oxide film on SS was divided into two layers. Ni was concentrated mainly at the oxide/substrate interface. The oxide film formed on 309L was thicker than that on the 308L. The ferrite in the stainless steel could improve the oxidation resistance.

TAS-Based Incremental Hybrid Decode–Amplify–Forward Relaying for Physical Layer Security Enhancement

In this paper, a transmit antenna selection (TAS)-based incremental hybrid decode–amplify–forward (IHDAF) scheme is proposed to enhance physical layer security in cooperative relay networks. Specifically, TAS is adopted at the source in order to reduce the feedback overhead. In the proposed TAS-based IHDAF scheme, the network transmits signals to the destination adaptive select direction transmission (DT) mode, AF mode, or DF mode depending on the capacity of the source-relay link and source-relay link. In order to fully examine the benefits of the proposed TAS-based IHDAF scheme, we first derive its secrecy outage probability (SOP) in a closed-form expression. We then conduct asymptotic analysis on the SOP, which reveals the secrecy performance floor of the proposed TAS-based IHDAF scheme when no channel state information is available at the source. Theoretical analysis and simulation results demonstrate that the proposed TAS-based IHDAF scheme outperforms the selective decode-and-forward, the incremental decode-and-forward, and the noncooperative DT schemes in terms of the SOP and effective secrecy throughout, especially when the relay is close to the destination. Furthermore, the proposed TAS-based IHDAF scheme offer a good tradeoff between complexity and performance compared with using all antennas at the source.

Microstructural Evolution and Hardness Profile of High Nitrogen Austenitic Steel After Arc-laser Hybrid Welding

An arc-laser hybrid welding was performed on high nitrogen austenitic steel which was used in the industries. Micro-vickers hardness tester, Optical microscopy, secondary and backscattered electron beam image analysis, image analyzer and Energy Dispersive X-ray Spectroscopy (EDS) in Scanning Electron Microscopy (SEM) were applied to reveal the microstructural details. The results indicate that, the microstructures of the weld bead are consisted of the dendrite-like austenitic phase and the small rod-like delta ferritic phase located between the dendrites. The solidification mode of the bead is AF mode. The grain size in heat affected zone (HAZ) is larger than the parent metal, and the near the bead area, the larger the size of the grain.

617. Identification of Novel AAV Capsid Variants with Enhanced Tropism for the Canine Outer Retina Following Intravitreal Delivery

The delivery of AAV vectors across physical barriers to target the outer retina is key to the success of retinal gene therapies. Subretinal injection of AAV vectors is the most common approach to deliver genes to photoreceptors and RPE; however, this route of administration presents surgical challenges and potential complications, as well as mediates transfer to only a limited region of the retinal surface. Intravitreal administration may represent a safer way of targeting larger areas of the outer retina; physical barriers such as the internal limiting membrane significantly limit efficiency of natural AAVs through this route. In a prior murine proof of concept study, we showed that directed evolution is promising method for engineering new AAV capsid variants with enhanced permissivity for the outer retina. Here, we show results from a screen performed in the canine retina, a large animal model with eye structure and size similar to the human eye. A library of >107 distinct capsid variant AAV vectors was injected intravitreally into the eye of a wildtype dog. A subset of the AAV vectors injected was recovered from samples of outer retina by PCR amplification. Isolated variants were then pooled and re-injected in additional wildtype canine eyes, and following 5 total rounds of selection the pool had converged to a relatively small number of variants. High throughput sequencing was used to characterize the convergence of variants over all rounds of selection. The final candidate variants were then evaluated by packaging a GFP reporter controlled by a ubiquitous CAG promoter. Retinal distribution and cellular tropism of the variants was examined by cSLO (AF mode) imaging, histology and immunocytochemistry. Nineteen variants were identified as candidate vectors for targeting the canine outer retina. Intravitreal injection of a mixture of equal amounts of these variants carrying GFP fused to a barcode resulted in efficient targeting of all retinal layers including photoreceptors and RPE in 6 eyes of 3 wildtype dogs. Thus, directed evolution performed in a large animal model, with an eye structure similar to that of humans, resulted in new AAV capsid variants with improved abilities to bypass significant structural barriers and efficiently transduce the outer retina. High throughput sequencing allowed for identification of promising variants and monitoring of convergence. These vectors show promise for gene therapy delivery via the intravitreal route of administration, potentially providing a safer approach for targeting a larger area of outer retina than currently achieved by the more traumatic and focal subretinal injection method.

Actividad física de adolescentes: implicación de sustancias nocivas, modalidad practicada y familia

Resumen Los objetivos de la investigación fueron: determinar los niveles de práctica de actividad física en adolescentes, consumo de tabaco y alcohol como fenómeno social, establecer qué tipo de actividad y nivel federativo y dictaminar el nivel de AF en los progenitores; y apreciar cómo influye en la práctica de actividad física regular, el consumo de sustancias, el tipo de deporte practicado y el nivel de práctica de padres y madres. Participaronun total de 2.134 adolescentes, empleándose una hoja de autoregistro para las variables: Práctica de AF, Modalidad, Estado Federativo y Nivel de Actividad Física Familiar; el FTND para determinar elConsumo de Tabacoy el AUDIT para elConsumo de Alcohol.Los principales resultados indican que los adolescentes que practican actividad física no consumen habitualmente sustancias nocivas, están influenciadospor parámetros familiares, realizanen mayor medida deportes de tipo colectivo y están federados en ellos.

Crystal growth and spin reorientation transition in Sm0.4Er0.6FeO3 orthoferrite

Abstract High quality Sm0.4Er0.6FeO3 single crystal has been successfully grown by the floating zone method. Temperature dependence of the magnetizations of Sm0.4Er0.6FeO3 under ZFC process is studied in the temperature range of 4–300 K. Spin reorientation transition between Γ2 (Gz, Fx) and Γ4 (Gx, Fz) is observed in the temperature range of 170–210 K, which is significantly lower than that of SmFeO3, while much higher than that of ErFeO3. A compensation point (35.8 K) corresponding to zero magnetization and a spontaneous magnetization reversal transition at 49.5 K are observed in Sm0.4Er0.6FeO3. Temperature-induced SRT of Sm0.4Er0.6FeO3 is systematically studied by THz-TDS range from 40 K to 300 K. The temperature dependence of amplitude of AFM mode coincides well with the magnetization measurement which demonstrate that SRT in Sm0.4Er0.6FeO3 can be studied through the amplitude of AFM mode FID emission. The AF mode frequency is almost invariant, while the F mode frequency significantly decreases with increasing temperature, which could be explained by the temperature dependence of anisotropy energy.

Adaptive decode-and-forward protocol-based cooperative spectrum sensing in cognitive radio

In this paper, a multiple-user cooperative spectrum sensing MCSS scheme based on a hybrid relay protocol is proposed to achieve the spatial diversity gains in detection of primary user in a cognitive radio CR networks. The proposed hybrid relay protocol adaptive decode-and-forward protocol works adaptively uses either AF or DF mode of relay operation. Closed-form expressions of detection probability P

Fundus Autofluorescence Findings in a Mouse Model of Retinal Detachment

Fundus autofluorescence (fundus AF) changes were monitored in a mouse model of retinal detachment (RD). RD was induced by transscleral injection of hyaluronic acid (Healon) or sterile balanced salt solution (BSS) into the subretinal space of 4-5-day-old albino Abca4 null mutant and Abca4 wild-type mice. Images acquired by confocal scanning laser ophthalmoscopy (Spectralis HRA) were correlated with spectral domain optical coherence tomography (SD-OCT), infrared reflectance (IR), fluorescence spectroscopy, and histologic analysis. Results. In the area of detached retina, multiple hyperreflective spots in IR images corresponded to punctate areas of intense autofluorescence visible in fundus AF mode. The puncta exhibited changes in fluorescence intensity with time. SD-OCT disclosed undulations of the neural retina and hyperreflectivity of the photoreceptor layer that likely corresponded to histologically visible photoreceptor cell rosettes. Fluorescence emission spectra generated using flat-mounted retina, and 488 and 561 nm excitation, were similar to that of RPE lipofuscin. With increased excitation wavelength, the emission maximum shifted towards longer wavelengths, a characteristic typical of fundus autofluorescence. In detached retinas, hyper-autofluorescent spots appeared to originate from photoreceptor outer segments that were arranged within retinal folds and rosettes. Consistent with this interpretation is the finding that the autofluorescence was spectroscopically similar to the bisretinoids that constitute RPE lipofuscin. Under the conditions of a RD, abnormal autofluorescence may arise from excessive production of bisretinoid by impaired photoreceptor cells.

Microstructures of Austenitic Stainless Steel Produced by Twin-Roll Strip Caster

The microstructures of austenitic stainless steel strip were studied using color metallographic method and electron probe micro analysis (EPMA). In the cast strips, there are three kinds of solidification structures: fine cellular dendrite in the surface layer, equiaxed grains in the center and fine dendrite between them. The solidification mode in the surface layer is the primary austenite AF mode because of extremely high cooling rate, with the retained ferrite located around the primary cellular austenite. In the fine dendrite zone, the solidification mode of molten stainless steel changes to FA mode and the residual ferrite with fish-bone morphology is located at the core of the dendrite. The retained ferrite of equiaxed grains in the center is located in the center of broken primary ferrite dendrite with vermicular morphology.

Effect of Cr/Ni equivalent ratio on ductility-dip cracking in AISI 316L weld metals

The ductility-dip cracking (DDC) susceptibility of AISI 316L stainless steel weld metals was examined. Modified flux cored arc welding (FCAW) filler wires were fabricated with various chromium and nickel contents. The solidification mode and delta-ferrite content were determined from the chromium and nickel equivalent ratios (Cr eq/Ni eq). Ductility-dip cracking occurred through a grain boundary sliding mechanism in the reheated region of the weld metal in the ferrite at cell and dendrite boundaries (AF mode), and the primary course of DDC formation was associated with the straight migrated grain boundary (MGB) morphology. No DDC was observed in the tortuous MGB due to the pinning effect of delta-ferrite in the continuous network of vermicular type of ferrite (FA mode)/acicular ferrite and continuous austenite network (F mode) weld metals. The DDC at the triple point or the intersection of the MGB showed a creep-like morphology. Severe localized and thermal plastic deformation was observed through the formation of micro-voids when grain boundary sliding was generated in the ductility-dip temperature range under strong restraint conditions.

Analysis of the Solidification Process of Austenitic Stainless Steel Weld Metal using Synchrotron Radiation

A numerical model to predict the solidification microstructure and solidification cracking susceptibility of austenitic stainless steel weld metals was proposed. It was predicted using the developed numerical model that Fe-20 %Cr-14.4 %Ni, Fe-20 %Cr-12.7 %Ni, Fe-20 %Cr-11.5 %Ni and Fe-20 %Cr-9.8 %Ni weld metals solidified as A mode (L→L + γ→γ), AF mode (L→L + γ→L + γ + δ→γ + δ), FA mode (L→L + δ→L + δ + γ→δ + γ) and FA mode, respectively. Also, it was found that the effect of Ni content on the solidification cracking susceptibility of Fe-20 %Cr-(9.8–14.4) %Ni weld metal, determined via trans-Varestraint testing, agreed with the results calculated using the model. In addition, in order to verify the validity of the developed numerical model, time-resolved in-situ observation of welding solidification process using synchrotron radiation has been carried out by changing the welding speed from 1 mm/s to 10 mm/s for Fe-20 %Cr-12.5 %Ni and Fe-20 %Cr-11.4 %Ni weld metals. It was found that the solidification mode of Fe-20 %Cr-12.5 %Ni weld metal transited from FA mode to AF mode by the higher welding speed and that of Fe-20 %Cr-11.4 %Ni weld metal maintained FA mode under the welding speed range of 1 mm/s to 10 mm/s. These results also coincided with the calculated results for Fe-20 %Cr-12.5 %Ni and Fe-20 %Cr-11.4 %Ni weld metals using the developed numerical model.

Low-Temperature Aging Characteristics of Type 316L Stainless Steel Welds: Dependence on Solidification Mode

Thermal aging embrittlement of light water reactor (LWR) components made of stainless steel cast has been recognized as a potential degradation issue, and careful attention has been paid to it. Although welds of austenitic stainless steels have γ-δ duplex microstructure, which is similar to that of the stainless steel cast, examination of the thermal aging characteristics of the stainless steel welds is very limited. In this investigation, two types of type 316L stainless steel weld metal with different solidification modes were prepared using two kinds of filler metals having tailored Ni equivalent and Cr equivalent. Differences between the two weld metals in the morphology of microstructure, in the composition of δ-ferrite, and in hardening behaviors with isothermal aging at 335 °C have been investigated. The hardness of the ferrite phase has increased with aging time, while the hardness of austenite phase has stayed the same. The mottled aspect has been observed in δ-ferrite of aged samples by transmission electron microscopy (TEM) observation. These characteristics suggest that spinodal decomposition has occurred in δ-ferrite by aging at 335 °C. The age-hardening rate of δ-ferrite was faster for the primary austenite solidification mode (AF mode) sample than the primary ferrite solidification mode (FA mode) sample in the initial stage of the aging up to 2000 hours. It has been suggested that the solidification mode can affect the kinetics of spinodal decomposition.

放射光を利用したオーステナイト系ステンレス鋼溶接凝固過程の解析

In order to verify the validity of the developed numerical model to predict the solidification microstructure of austenitic stainless steel weld metal proposed in the previous report, spatially resolved X-ray diffraction measurements using synchrotron radiation have been carried out for Fe-20Cr-11.5Ni and Fe-20Cr-12.7Ni weld metals, quenched in liquid tin. X-ray diffraction analysis of Fe-20Cr-11.5Ni quenched weld metal, solidifying in FA mode (L→L +δ→L +δ+γ→δ+γ), showed that the leading γ phase crystallized in a eutectic growth mode down to a temperature drop of 6 K from the initiation of solidification. Also, from X-ray diffraction analysis of Fe-20Cr-12.7Ni quenched weld metal, which solidified in AF mode (L→L +γ→L +γ+δ→γ+δ), it was found that the leading δ phase crystallized in a eutectic growth mode within the temperature drop range between 18 and 24 K from the initiation of solidification. The crystallization temperatures predicted by the developed numerical model for leading γ and δ phases in Fe-20Cr-11.5Ni and Fe-20Cr-12.7Ni weld metals agreed with experimental data. These agreements support the validity of the developed numerical model. Furthermore, time-resolved in-situ observation of welding solidification process using synchrotron radiation have been carried out for Fe-20Cr-12.5Ni and Fe-20Cr-11.4Ni weld metals, it was found that γ and δ phase crystallized down to a temperature drop within about 47 K and 55 K from the initiation of solidification respectively. These results also coincided with the calculated results for Fe-20Cr-12.5Ni and Fe-20Cr-11.4Ni weld metal using the developed numerical model.

速度依存性を考慮したオーステナイト系ステンレス鋼溶接凝固過程の数値解析

A numerical model to predict the solidification microstructure and solidification cracking susceptibility of austenitic stainless steel weld metal is proposed by taking into account the non-equilibrium theory. It was predicted using the developed numerical model that Fe-20Cr-14.4Ni, Fe-20Cr-12.7Ni, Fe-20Cr-11.5Ni and Fe-20Cr-9.8Ni weld metals solidified as A mode (L→L +γ→γ), AF mode (L→L +γ→L +γ+δ→γ+δ), FA mode (L→L +δ→L +δ+γ→δ+γ) and FA mode, respectively. Also, it was found that the effect of Ni content on the solidification cracking susceptibility of Fe-20Cr-(9.8-14.4)Ni weld metal, determined via Trans Varestraint testing, agreed with the results calculated using the model. Furthermore, it was found that the content of δ ferrite at just solidifying calculated using the model agreed with the results measured using Fe-20Cr-(11.5-14.4)Ni weld metals quenched in liquid Sn. These agreements support the validity of the developed numerical model.

Ｃｒ‐Ｎｉ系ステンレス鋼溶接金属の凝固・変態に関する研究 第１報 初晶オーステナイトで凝固するオーステナイト系ステンレス鋼溶接金属の凝固・変態挙動

Solidification and subsequent transformation behavior of two Fe-Cr-Ni stainless steel welds were investigated by using liquid-tin quenching method. One weld metal solidified as austenitic single phase solidification mode (A mode), and the other as austenitic-ferritic solidification mode (AF mode). In the weld metal solidified as A mode, both Cr and Ni were enriched in interdendritic regions during solidification, where the degree of enrichment of Cr was larger than that of Ni. The microstructural characteristics formed during solidification, concentration profiles of elements and crystallographic orientation, were similarly observed at room temperature. In the case of AF mode solidification, globular ferrite was formed through the eutectic reaction at cell boundaries. The ‹100›r direction of the primary austenite was found to be parallel to the ‹100›δ direction of the eutectic ferrite and the both phases were found to grow along the preferential growth directions.