Tensile and High Cycle Fatigue Performance at Room and Elevated Temperatures of Laser Powder Bed Fusion Manufactured Hastelloy X.

The application potential of additive manufacturing nickel-based superalloys in aeroengines and gas turbines is extensive, and evaluating their mechanical properties is crucial for promoting the engineering application in load-bearing components. In this study, Hastelloy X alloy was prepared using the laser powder bed fusion process combined with solution heat treatment. The tensile and high cycle fatigue properties were experimentally investigated at room temperature as well as two typical elevated temperatures, 650 °C and 815 °C. It was found that, during elevated-temperature tensile deformation, the alloy exhibits significant serrated flow behavior, primarily observed during the initial stage of plastic deformation at 650 °C but occurring throughout the entire plastic deformation process at 815 °C. Notably, when deformation is small, sawtooth fluctuations are significantly higher at 815 °C compared to 650 °C. Irregular subsurface lack of fusion defects serve as primary sources for fatigue crack initiation in this alloy including both single-source and multi-source initiation mechanisms; moreover, oxidation on fracture surfaces is more prone to occur at elevated temperatures, particularly at 815 °C.

The role of internal defects on anisotropic tensile failure of L-PBF AlSi10Mg alloys.

This paper investigates the effects of defects on tensile failure of additive manufactured AlSi10Mg alloy focusing particularly on the role of large pancake shaped loss of fusion (LOF) defects lying perpendicular to the build direction (BD). Time-lapse in situ synchrotron radiation X-ray micro-computed tomography during straining reveals how, when tested parallel to the BD, the LOF defects extend laterally with straining connecting to other defects and giving rise to low plasticity and an essentially brittle failure mode. When they are aligned edge-on to the straining direction, failure is characterised by a ductile cup-cone failure with significant elongation of the defects axially and extensive necking prior to failure. The soft fish-scale melt pool boundaries were also found to affect the fracture path. These results highlight the anisotropic effect of loss of fusion defects in controlling tensile ductility and the need to minimize their size and aspect ratio. In cases where these cannot be fully eliminated the component should be fabricated such that the BD is not aligned with the dominant in-service loading direction.

Inhibiting weld cracking in high-strength aluminium alloys.

Cracking from a fine equiaxed zone (FQZ), often just tens of microns across, plagues the welding of 7000 series aluminum alloys. Using a multiscale correlative methodology, from the millimeter scale to the nanoscale, we shed light on the strengthening mechanisms and the resulting intergranular failure at the FQZ. We show that intergranular AlCuMg phases give rise to cracking by micro-void nucleation and subsequent link-up due to the plastic incompatibility between the hard phases and soft (low precipitate density) grain interiors in the FQZ. To mitigate this, we propose a hybrid welding strategy exploiting laser beam oscillation and a pulsed magnetic field. This achieves a wavy and interrupted FQZ along with a higher precipitate density, thereby considerably increasing tensile strength over conventionally hybrid welded butt joints, and even friction stir welds.

Synergistic Benefit of Adoptive T Cells in Combination With Chemoradiotherapy Against Metastatic Prostate Cancer Cells.

BACKGROUND/AIM: Prostate cancer (PC) is one of the major diseases that affects male health and ranks as the second most frequent cancer in men worldwide. Although most newly-diagnosed PCs are well-differentiated tumors with a high cure probability, there are some patients with aggressive malignancies that show potential for recurrence and metastasis. Cytotoxic T lymphocytes are a specific immune effector cell population that mediates immune responses against cancer. MATERIALS AND METHODS: In the present study, the cytotoxicity of peripheral blood mononuclear cells (PBMCs)-derived γδ T cells and cytokine-induced killer (CIK) cells in combination with chemoradiotherapy against PC cells was evaluated using Alamar blue cell viability and cell membrane permeability assays. RESULTS: Advanced PC-3 cells, which were more resistant to docetaxel (Doc), also showed higher viability following pretreatment with radiation. The cell proliferation inhibition was significantly increased upon additional γδ T or CIK treatment. Furthermore, the proportion of apoptotic cells was significantly (p<0.05) increased in the Doc-γδ T cell co-treatment group as compared with the Doc or γδ T cell treated alone group. CONCLUSION: γδ T cell therapy may provide additional benefit compared to traditional chemoradiotherapy for PC treatment.

Effects of Concurrent Chemoradiotherapy on the Metastasis and the Mesenchymal Transition of Bladder Urothelial Carcinoma Cells.

BACKGROUND/AIM: Cancer stem cells (CSCs) have been suggested playing a crucial role in the tumorigenesis and tumor progression. Clinically, concurrent chemoradiotherapy (CCRT) after transurethral resection of the bladder is the widely accepted treatment option for high-grade bladder urothelial carcinoma (UC); however, a proportion of bladder UC patients still suffer from recurrence and metastasis. In the present study, we investigated the stemness properties of bladder UC cells with respect to various disease stages. The metastatic capability and epithelial-mesenchymal transition (EMT) of the parental cells and the CSC cells of bladder UC, after chemotherapy with cisplatin alone or CCRT were also studied, respectively. MATERIALS AND METHODS: The aldehyde dehydrogenase (ALDH)-positive cells were analyzed by a flow cytometer. The inhibitory effects of radiation in combination with cisplatin on the cell viability, migration, invasion and EMT characteristics were also examined. RESULTS: We found that the proportion of ALDH+-CSCs of bladder UC cells and the disease grading were independent. Furthermore, cisplatin alone significantly (p<0.05) enhanced the migration of both grade-III T24 cells and advanced-stage HT1197 cells, while CCRT treatment significantly (p<0.05) inhibited the T24 cell migration capability, compared to the cisplatin alone group. Interestingly, we found that the cell invasion capability was obviously increased upon the treatment with CCRT in both T24 and HT1197 CSCs. Furthermore, cisplatin played a promoting role in EMT whether in the presence or absence of irradiation. CONCLUSION: CSCs as well as EMT signaling might contribute to the resistance and metastasis of one-shot CCRT in malignant bladder cancer.

Malakoplakia and xanthogranulomatous pyelonephritis treated with nephrectomy: A case report.

RATIONALE: Malakoplakia and xanthogranulomatous pyelonephritis are chronic inflammatory conditions of the kidney characterized by the infiltration of inflammatory cells. PATIENT CONCERNS: An 82-year-old female patient had a history of hypertension, type 2 diabetes mellitus, dyslipidemia, and end-stage renal disease under hemodialysis. She was admitted repeatedly 4 times within 4 months due to urosepsis. DIAGNOSIS: The enlarged right kidney with a low-density lesion at the right middle calyx, and a well-enhanced ureter were noted on the computed tomography scan. Therefore, xanthogranulomatous inflammation was suspected. Semi-rigid ureteroscopy with biopsy was performed, and xanthogranulomatous inflammation of the ureter was confirmed on the pathology report. INTERVENTIONS: After right open radical nephrectomy was performed, the final pathology report revealed malakoplakia with xanthogranulomatous pyelonephritis. OUTCOMES: After the surgery, she has no longer suffered from urosepsis for 8 months, and there were no adverse event or recurrence noted. LESSONS: With this case report, we aim to emphasize that these 2 diseases are not mutually exclusive, but they may exist simultaneously in the same patient.

Internal crack characteristics in very-high-cycle fatigue of a gradient structured titanium alloy.

Gradient structure (GS) is commonly designed and processed in engineering materials to improve mechanical properties especially fatigue performance by taking advantage of the strengthened surface. However, whether the very-high-cycle fatigue (VHCF) property can be improved by GS is questioning due to the different crack initiation mechanisms between low-, high-cycle and VHCF. In this paper, GS of a Ti-6Al-4V alloy is generated by pre-torsion and characterized by electron backscatter diffraction. Then the VHCF behavior of the GS specimen is studied. The fractography and synchrotron radiation X-ray microtomography presented detailed characteristics of the internal crack initiation region in VHCF of the titanium alloy with GS. The results indicated that, in contrast to the low- and high-cycle regimes, the VHCF strength is reduced for the specimens with GS. Thus, the GS induced by pre-torsion cannot enhance the VHCF strength of the titanium alloy. This implies that VHCF test (property) is an important consideration for the microstructural designed materials. The graphical abstract is available in Supplementary information.

Villous adenoma of the ureter with manifestation of mucus hydroureteronephrosis.

Ureteral tumor is prone to result in lumen obstruction. Villous adenoma is most frequently found in the colon and rectum, seldom in the urinary tract and even more rarely in the ureter or pelvis. Herein, we present a case of bilateral renal stones of more than 10 years' duration with the chief complaint of right flank pain. Obstruction of the right upper ureter with hydroureteronephrosis was observed on sonography, computed tomography and retrograde pyelography. Ureteroscopy revealed papillary tumor obstructing the upper third of the ureter and inducing hydroureteronephrosis with abundant mucoid content. The ureteral tumor proved to be villous adenoma by pathologic examination. It should be noted that ureteral villous adenoma may be related to previous enteric-type metaplastic mucosa or ureteritis glandularis, demonstrates profuse production of mucus, and may eventually undergo malignant transformation.