Long-term creep rupture strengths and the microstructural stability of ASME P92 and P122 pipes have been studied using creep testing at the temperatures from 550 to 700
°C and detailed scanning ...transmission electron microscopy. Creep rupture strength of P92 is found to be more stable than that of P122 at temperatures over 600
°C, which is mainly due to the difference in their Cr content. P122 type model steel with reduced Cr content, 9%Cr, has been prepared to explore the effect of Cr on the stability of MX and formation of Z-phase during creep deformation. MX in 9%Cr steel is found to be stable even after prolonged exposure at 650
°C, while Cr and Fe concentration to MX without marked coarsening has been observed in 10.5%Cr steel after aging for 10,000
h at 650
°C. This seems to lead to the transition of MX carbonitride into the Z-phase after aging for 23,000
h, which requires ordering in a M
2N lattice to achieve a tetragonal Z-phase to be stable. Creep deformation behavior in the transient creep region of the steels is almost same up to about 7000
h, while in the acceleration creep region the creep rate of 10.5%Cr steel becomes much faster than that of 9%Cr steel, resulting in shorter rupture life. It is obvious that the creep rupture strength degradation starts prior to the formation of Z-phase in 10.5%Cr steel. It is thus concluded that Z-phase is not a necessary factor for degradation of creep rupture strength but the instability of the fine precipitates such as Cr
2(C, N) caused by the compositions change like Cr supply to MX carbonitride is more essential.
A two-dimensional perovskite incorporating an amine moiety with a carboxyl group exhibited variations in orientation with changes in the ambient humidity. It was possible to increase the degree of ...vertical orientation by optimizing the film thickness and promoting crystallization at the interface between the film and the film-forming atmosphere.
Factors determining the orientation of two-dimensional perovskites were examined.
Biomarkers are needed for noninvasive early detection of gastric cancer (GC). We investigated salivary extracellular RNA (exRNA) biomarkers as potential clinical evaluation tools for GC.
Unstimulated ...whole saliva samples were prospectively collected from 294 individuals (163 GC and 131 non-GC patients) who underwent endoscopic evaluation at the Samsung Medical Center in Korea. Salivary transcriptomes of 63 GC and 31 non-GC patients were profiled, and mRNA biomarker candidates were verified with reverse transcription quantitative real-time PCR (RT-qPCR). In parallel, microRNA (miRNA) biomarkers were profiled and verified with saliva samples from 10 GC and 10 non-GC patients. Candidate biomarkers were validated with RT-qPCR in an independent cohort of 100/100 saliva samples from GC and non-GC patients. Validated individual markers were configured into a best performance panel.
We identified 30 mRNA and 15 miRNA candidates whose expression pattern associated with the presence of GC. Among them, 12 mRNA and 6 miRNA candidates were verified with the discovery cohort by RT-qPCR and further validated with the independent cohort (n = 200). The configured biomarker panel consisted of 3 mRNAs (
,
, and
) and 2 miRNAs (
and
), which were all significantly down-regulated in the GC group, and yielded an area under the ROC curve (AUC) of 0.81 (95% CI, 0.72-0.89). When combined with demographic factors, the AUC of the biomarker panel reached 0.87 (95% CI, 0.80-0.93).
We have discovered and validated a panel of salivary exRNA biomarkers with credible clinical performance for the detection of GC. Our study demonstrates the potential utility of salivary exRNA biomarkers in screening and risk assessment for GC.
Static recovery of tempered lath martensite microstructures of strength enhanced ferritic steels has been investigated during very long-term aging up to 2
×
10
4
h at 650
°C for 3 steels containing 9 ...to 12% Cr. Static recovery of tempered lath martensite microstructure occurs after an incubation period for 1–2
×
10
3
h in the steels. The static recovery is controlled by the loss of strengthening due to M
23C
6 precipitates, and disappearance of MX carbonitrides cannot be the main cause of the static recovery.
In radiation therapy, for accurate radiation dose delivery to a target tumor and reduction of the extra exposure of normal tissues, real-time tumor tracking is typically an important technique in ...lung cancer treatment since lung tumors move with patients' respiration. To observe a tumor motion in real time, x-ray fluoroscopic devices can be employed, and various tracking techniques have been proposed to track tumors. However, development of a fast and accurate tracking method for clinical use is still a challenging task since the obscured image of the tumor can cause decreased tracking accuracy and can result in additional processing time for remedying the accuracy. In this study, a new key-point-based tumor tracking method, which is sufficiently fast and accurate, is presented. Given an x-ray image sequence, the proposed method employs a difference-of-Gaussians filtering technique to detect key points in the tumor region of the first frame which are robust against noise and outliers in the subsequent frames. In the subsequent frames, these key points are tracked using a fast optical flow technique, and tumor motion is estimated via their movement. To evaluate the performance, the proposed method has been tested on several clinical kV and MV x-ray image sequences. The experimental results showed that the average of the root mean square errors of tracking were and for kV and MV x-ray image sequences, respectively. This tracking performance was more accurate than previous tracking methods. In addition, the average processing times for each frame were and for kV and MV image sequences, respectively, and the proposed method was faster than previous methods as well as shorter than frame acquisition interval. Therefore, the proposed method has the potential for both highly accurate and fast tumor tracking in clinical applications.
•TMF life of 23Cr-45Ni-7W alloy is presented.•Higher stress is generated in the TMF test than the isothermal fatigue test.•Strain range partitioning method is useful to predict the TMF life of the ...alloy.
This study focuses on thermo-mechanical fatigue (TMF) behaviors of nickel-based 23Cr-45Ni-7W alloy for pipes and tubes in high-efficiency power boilers. TMF tests (maximum temperature = 700 °C; minimum temperature = 100 °C) were conducted under in-phase (IP) and out-of-phase (OP) conditions. The lives under the IP condition is 0.30–0.44 times of that under the OP condition when same total strain range, Δεt, is applied. The TMF properties obtained via the tests are compared with the results of isothermal fatigue (ITF) tests conducted at 700 °C and bithermal fatigue (BTF) tests with maximum and minimum temperatures of 700 °C and 100 °C, respectively. The fracture morphology for each type of TMF, ITF, and BTF is similar under the test conditions of this study. Intergranular cracking is predominant under application of cyclic tensile creep strain during the fatigue tests, and transgranular cracking is predominant under application of cyclic compressive creep strain during the fatigue tests. The inelastic strain range–fatigue life (Δεin–Nf) relation in the TMF test and the inelastic strain range components–life (Δεij–Nij) relation determined using the strain range partitioning method show a good agreement within a factor of 1.5 scatter band. These results indicate the possibility of predicting the TMF life of the 23Cr-45Ni-7W alloy using the results of the ITF test by considering the amount and direction (tension or compression) of creep strain applied to the alloy.
In order to better understand the dynamical evolution and star formation history of the Magellanic system, realistic N-body simulations of the tidal distortion of the Small Magellanic Cloud (SMC) as ...a result of the Galaxy and the Large Magellanic Cloud have been carried out, taking into account gas dynamics and star formation processes explicitly. The best model succeeds in reproducing the observed structural, kinematic and star formation properties of the SMC, including other related tidal features in the Magellanic system, without resorting to the ram pressure model. The best-fitting simulation reproduced a gas stream with almost no stars and the observed H i gas fraction, for which the morphology and velocity field agree quite well with those of the Magellanic stream, a result of adopting an initial SMC model that has a compact stellar disc embedded in an extended gaseous disc. This implies that the existence of a purely gaseous Magellanic stream does not pose serious problems to a tidal model of formation. Also, in this best model, the central and south-east side (wing region) of the SMC contained an excess of young stars, as is observed. Comparison with a reference simulation of isolated evolution demonstrated that the acceleration of star formation activity in these regions may be a direct result of the last interaction between the Magellanic Clouds roughly 0.2 Gyr ago, which formed the inter-cloud region. The large extent in depth of the SMC implied by the spatial distribution of Cepheids, and the line-of-sight velocity pattern in H i around the SMC is also reproduced. Finally, the dependences of these results on the numerical parameters that specify the SMC mass model and interstellar gas processes are discussed.
MgB
2
is a metal compound superconductor which has critical temperature value ~ 39 K. The critical temperature of MgB
2
superconducting wire is higher than Nb-based superconductor, NbTi and Nb
3
Sn. ...It is a promising superconductor to replace the Nb-based superconductor that has been applied as a widely used superconducting wire. The aim of this study is to synthesize MgB
2
superconductor with the various amount of Mg element using powder-in-sealed-tube method. Mg and B powders were mixed, grounded and poured into stainless steel SS304 tube. As-mixed powder was then heated at 800 C for 2 h in standard air ambient inside a sealed tube. After that, the crystal structures, surface morphology and resistivity versus temperature of all samples were characterized using X-ray diffraction (XRD), scanning electron microscopy and cryogenic system, respectively. Based on the result of XRD, the majority of MgB
2
phase was formed even though there were slightly small amount of B
2
O phases. The critical temperature (
T
c
) onset of MgB
2
with the addition of 0, − 5, − 10, 5 and 10 wt% Mg was calculated 42.03; 42.25; 42; and 41.8 K, accordingly. These critical temperature values are relatively higher than other studies among this type of superconductors. And then, to study the grinding effect, one of the as-calcined pellets was ground and pressed to form bulk sample again.
T
C,onset
and
T
C,zero
of this sample were decreased 3 and 18 K, respectively.
PDF
