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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Use and misuse of large-density asymptotics in the reaction-infiltration instability

Analyzing the dissolution of rocks and other porous materials is simplified by the large dis-parity between mineral and reactant concentrations. In essence, the porosity remains frozen on the time scale of the reactant transport, which can then be treated as a quasi-stationary process. This conceptual idea can be derived mathematically using asymptotic methods, which show that the length scales in the system are, to a first approximation, independent of the ratio of reactant and mineral concentrations. Nevertheless, in a growing number of papers on dissolutional instabilities, the reactant-mineral concentration ratio has been incorrectly linked to the thickness of the dissolution front. In this paper we critically review the application of asymptotic methods to the reaction-infiltration instability. In particular, we discuss the limited validity of the thin-front or ‘‘Stefan’’ limit, where the interface between dissolved and undissolved mineral is sharp.

58 GEOSCIENCES↗
DOE OSTI2020

Processing and properties of SiC composites made via binder jet 3D printing and infiltration and pyrolysis of preceramic polymer

The effect of polymer infiltration and pyrolysis (PIP) cycles with polycarbosiloxane on the microstructure, air leak rate, and properties of SiC composites manufactured by a combination of binder jet 3D printing and PIP are reported. The density, Young’s modulus and flexural strength of disk-shaped components increased with the number of PIP cycles. In the case of density, it increased from 2.05 g/cm 3 in one PIP cycle to 2.33 g/cm 3 after three PIP cycles, while values of flexural strength and Young’s modulus at room temperature after three PIP cycles reached 66.8 ± 2.5 MPa and 69.5 ± 2.8 GPa, respectively. Conversely, the air leak rate was found to decrease with number of PIP cycles, and it reached a value of 4 mbar-liter/s after three cycles. The instantaneous coefficient of thermal expansion of the composite was found to change minimally with the number of PIP cycles and had a value of 4 ± 1.2 ppm/°C between 200°C and 1,000°C. Thermal conductivity was found to increase with number of PIP cycles and to decrease with temperature. For example, after 3 PIP cycles it was found to change from 6.72 ± 0.08 to 6.98 ± 0.08 W/mK at 25°C and 7.36 ± 0.08 to 7.96 ± 0.08 W/mK at 300°C. These values were lower than those of crystalline SiC because of the amorphous nature of the matrix and the presence of pores and cracks.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Tumor-Infiltrating Lymphocytes in Breast Cancer. Association with Clinical and Pathological Parameters

In patients with primary resectable breast cancer, a positive correlation between the age and the count of CD16{sup +} lymphocytes and a negative correlation of this parameter with the number of regulatory CD4{sup +}CD25{sup +}CD127{sup —} cells and proliferative activity of Ki-67 tumor cells were revealed. Higher level of Ki-67 was associated with reduced number of effector lymphocytes (CD8{sup +} and CD16{sup +}) and elevated content of regulatory CD8{sup +}CD11b{sup —}CD28{sup —} T cells. The absence of expression of estrogen receptors was associated with reduced cytotoxic potential of CD8{sup +} T cell in comparison with ER{sup +} breast cancer. The percentage of CD8{sup +} lymphocytes (CD3{sup +}CD8{sup +} and CD8{sup +}CD11b{sup +}CD28{sup +}) among lymphocytes infiltrating the tumor was higher in PR{sup +} breast cancer than in PR{sup —} tumors. With increasing the tumor load, the number of lymphocytes expressing CD16 marker and their cytotoxic potential decreased.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Optimization of the Dy Content in Single Crystalline GdBCO Bulk Superconductors Fabricated in Air Via Top-Seeded Infiltration Growth Process

Single-crystalline bulk GdBa{sub 2}Cu{sub 3}O{sub 7−δ} (GdBCO) superconductors were fabricated with top-seeded infiltration-growth technique (TSIG) in air by adding the different amounts of Dy{sub 2}BaCuO{sub 5} (Dy-211) particles (5, 10, 15, 20, 25, 30, 35, and 40 wt%). All the samples show superconducting critical temperature at ∼93 K with sharp transition irrespective of the chemical composition. X-ray diffraction measurements confirmed that all the samples were single domain with high alignment. Microstructural studies through scanning electron microscopy showed that TSIG-processed GdBCO samples contained 211 phase particles of two different sizes, i.e., ∼2–4 and ∼10 μ m. The addition of Dy-211 phase particles led to a significant enhancement of critical current density (J{sub c}) at 77 K. GdBCO superconductor with the addition of 20 wt% of Dy-211 showed the highest J{sub c} of 45.5 kA/cm {sup 2} at 77 K and self field.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Single-Grain Bulk YBa{sub 2}Cu{sub 3}O{sub y} Superconductors Grown by Infiltration Growth Process Utilizing the YbBa{sub 2}Cu{sub 3}O{sub y} + Liquid Phase as a Liquid Source

The top-seeded infiltration growth (IG) processed YBa{sub 2}Cu{sub 3}O{sub y} (Y-123) has several advantages compared to the same material produced by other melt process techniques. There is usually no shrinkage, a limited number of pores, and an uniform secondary phase particle dispersion in the Y-123 matrix. These characteristics of the IG process are very attractive for several industrial applications. In this paper, we produced a large single-grain Y-123 by IG and top seeded melt-growth process. Utilizing commercial YbBa{sub 2}Cu{sub 3}O{sub y} (Yb-123) and a homemade Y{sub 2}BaCuO{sub 5} (Y-211), we produced bulk YBa{sub 2}Cu{sub 3}O{sub y} samples using Yb-123 + liquid (1:1) as a liquid source. Four facet lines on the top surfaces of the as-grown samples indicated a uniform growth from the seed up to sample edges. Magnetization measurements by SQUID magnetometer showed a sharp superconducting transition with T{sub c},{sub onset} at 92.1 K. The critical current density at 77 K and self-field was 39,000 A/cm{sup 2}. Trapped field results confirmed that single grain Y-123 samples were produced utilizing the above process. Our results prove that Yb-123 + liquid (1:1) as a liquid source is effective in producing single grain Y-123 material by IG process.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

The impact of geologic parameters and water infiltration on the imprinting of 133Xe

Recent experiments have shown that atmospheric radioxenon passing over a sampling site can be transported into the shallow subsurface by barometric pressure changes. The STOMP simulator is used to examine the impact of seven hydrologic/geologic parameters and water infiltration on the imprinting of radioxenon from a transient plume during two pressure scenarios. Soil hydraulic conductivity was found to be the dominant factor in the amount of xenon imprinted to two meters, particularly in the case when plume passage coincides with increasing pressure.

Radioxenon, Medical isotope production, Barometric↗
DOE OSTI2019

Design and engineering of dispersion and loss in photonic crystal fiber 1 × 4 power splitter (PCFPS) based on hole size alteration and optofluidic infiltration

We have presented a technique based on optofluidic infiltration and air-holes diameter variation together to design a 1 × 4 photonic crystal fiber power splitter (PCFPS) which have very low dispersion (D): (0 ≤ D ≤ 2.5 (ps/nm/km) and very low loss (L): 0 ≤ L ≤ 0.025(dB/cm) in a wide range of wavelengths (1100–1700 nm). This approach allows us to control the dispersion of the fundamental mode in a PCF beam splitter by choosing appropriate refractive indices for liquids and suitable diameters for air-holes in PCF power splitter. In fact, the techniques, used in this paper are complementary of each other and give us more excellent results which are better than other reported results in researchers’ works so far. In this work, a new design of 1 × 4 photonic crystal fiber power splitter is proposed by using beam propagation method. An optical Gaussian signal at a wavelength of third communication window range (1550 nm) is inserted into the central core and equally is divided into four core (25% of the total input power interred to each core). In addition, the physical behavior of coupling characteristics is obtained by using coupled mode analysis. Numerical simulations show that input optical signal can be equally divided in photonic crystal fiber structure with low dispersion and low loss. The total size of proposed PCFPS is 30 µm × 30 µm × 1.2 mm, too.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Study of the Mechanism of Liquid Slag Infiltration for Lubrication in Slab Continuous Casting

Consistent and uniform lubrication of the solidifying shell, especially in the meniscus, is crucial for the smooth continuous casting operation and production of strands free of surface defects. Thus, the current study established a coupled model to study the inflow behavior of liquid slag to the mold-strand channel, taking the solidification of steel and slag and the periodic oscillation of mold into account. The difficulties and solutions for the simulation were described in detail. The predicted profiles of the slag rim and initial shell were in good agreement with the reports. The main results indicated that liquid slag could be squeezed out and back into the slag pool in a negative strip period while a large amount of liquid slag could infiltrate into the mold-strand channel. Thus, the amount of slag consumed in the negative strip period was relatively small compared with that in the positive strip period. The predicted variation of slag consumption during mold oscillation was periodic, and the average value was 0.274 kg/m{sup 2}, which agreed well with the slag consumption in industrial practice. The current model can predict and optimize the oscillation parameters aiming at stable lubrication conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Effect of Zr Content on Mechanical Properties of Diamond/Cu-Zr Composites Produced by Gas Pressure Infiltration

Diamond particle-reinforced Zr-alloyed Cu matrix (diamond/Cu-xZr) composites were produced by a gas pressure infiltration route, with x = 0.0, 0.3, 0.5, 0.75, and 1.0 wt.%. The x-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterization confirms the formation of ZrC at the diamond/Cu interface. With increasing Zr content, the tensile, bending, and compressive strengths of the diamond/Cu-Zr composites are found to firstly increase and then decrease. The maximum tensile, bending, and compressive strengths at 0.75 wt.% Zr are 108, 360, and 441 MPa, respectively. The variation of the mechanical properties is attributed to the formation of interfacial ZrC. The increase in amount of ZrC strengthens the interface, but large ZrC particles formed at high Zr content are harmful to the interfacial bonding. The result suggests that the mechanical properties of diamond/Cu composites can be enhanced by Cu matrix alloying with Zr.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microstructure and Mechanical Properties of W-ZrC Composites Synthesized by Reactive Melt Infiltration of Zr{sub 2}Cu into Porous Preforms from Partially Carburized W Powders

W-ZrC composites with different W contents from 48 to 73 vol.% have been synthesized by reactive melt infiltration of Zr{sub 2}Cu melt into porous preforms from partially carburized W powders at 1300 °C for 1 h in vacuum. The influences of carbon content and porosity in the preforms on microstructure and mechanical properties of W-ZrC composites are investigated. Cold isostatic pressing followed by pre-sintering process is used to produce porous preforms with suitable porosities of 53.6-47% under a pressure of 100 MPa to allow sufficient penetration of Zr{sub 2}Cu melt into the preforms. Small amounts of Cu-rich phases form in the synthesized W-ZrC composites after a complete reaction of y/2xZr{sub 2}Cu(l) + WC{sub y}(s) = y/xZrC{sub x}(s) + W(s) + y/2xCu(l). These Cu-rich phases are distributed not only at the phase boundaries of W matrix and ZrC grains, but also in the interior of ZrC{sub x} grains. With decreasing W content from 73 to 48 vol.% in the W-ZrC composites, the flexural strength and fracture toughness increase from 519 to 657 MPa and from 9.1 to 10.6 MPa m{sup 1/2}, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Development of Pore-Free Ti-Si-C MAX/Al-Si Composite Materials Manufactured by Squeeze Casting Infiltration

Open-porous MAX phase skeletons from Ti{sub 3}SiC{sub 2} were manufactured by Microwave-Assisted Self-propagating High-temperature Synthesis (MASHS) and subsequently subjected to squeeze casting infiltration with an Al-Si lightweight casting alloy (EN AC-44200). This alloy was chosen due to its high flowability, corrosion resistance and good machinability. The manufactured composites, together with a reference sample of the original alloy, underwent testing of thermal properties, including thermal conductivity and diffusivity, specific heat and thermal expansion in the temperature range 50-500 °C, which corresponds to the expected working temperatures of the material. The fabricated AlSi/Ti{sub 3}SiC{sub 2} composites have significantly increased thermal stability, with coefficients of thermal expansion (approximately 10-11 × 10{sup −6} °C{sup −1}) half that of the original alloy. As regards mechanical properties, the instrumental Young’s modulus and Vickers hardness of the composite materials are 170.8 and 8.5 GPa, respectively. Moreover, the microstructure and phase composition, structural defects and potential impacts between constituents of the manufactured composites were characterized using SEM, TEM and STEM microscopy and EDS and XRD analysis.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Characteristics and impact of programmed death-ligand 1 expression, CD8+ tumor-infiltrating lymphocytes, and p16 status in head and neck squamous cell carcinoma

Background: No predictive biomarker of immune checkpoint inhibitors in head and neck squamous cell carcinoma (HNSCC) has been well established. The impact of programmed death-ligand 1 (PD-L1) expression, CD8+ tumor-infiltrating lymphocytes (TILs), and p16 status in HNSCC is unclear and may vary according to ethnicity. Methods: HNSCC patients treated between 2007 and 2013 were reviewed. Archival tissues were retrieved for PD-L1, CD8+ TILs, and p16 analyses. PD-L1 expression was evaluated by using the validated SP142 assay on the VENTANA platform. CD8+ TILs were defined by using semiquantitative scoring. Results: A total of 203 patients were analyzed. PD-L1 expression was observed in 80% of patients and was significantly associated with older age (P < 0.001). A high CD8+ TIL score (≥ 6) was significantly associated with never-smoking (P = 0.020), oral cavity cancer (P < 0.001), and stage M0 at presentation (P = 0.025). The p16 status was positive in 12% of patients. Patients with a high TIL score had a significantly longer OS (P = 0.032). Patients with PD-L1 expression of 1–49% and ≥ 50% were associated with a significantly shorter OS compared with those with PD-L1 < 1% (P = 0.027 and P = 0.011, respectively). Multivariate analysis showed that PD-L1 ≥ 50% was significantly associated with a poor OS. (HR 2.98 [95% CI 1.2–7.39]; P = 0.019.) Conclusions: A high prevalence of PD-L1 expression was observed in HNSCC using the validated SP142 assay. PD-L1 expression was associated with older age, while highly PD-L1 expression (≥ 50%) was an independent prognostic factor for poor OS in anti-PD1/PD-L1 untreated HNSCC patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Microvascular dysfunction in infiltrative cardiomyopathies

Infiltrative heart diseases are characterized by myocardial tissue alterations leading to mechanical dysfunction which in turn develops into bi-ventricular congestive heart failure. Also the coronary microvasculature undergoes significant remodeling and dysfunction. The effects of the unbalance of the mechanical cross-talk between cardiac muscle and vessels and of the impairment of vasodilatory function can be measured non-invasively by means of positron emission tomography and cardiac magnetic resonance.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2024

Efficacy of underground aggregate infiltration beds under a permeable pavement system

Urban areas often face significant flooding challenges due to impermeable surfaces that exacerbate stormwater runoff, making effective stormwater management essential. This study demonstrated that combining pervious concrete pavement systems with underground aggregate storage beds and rain gardens can significantly enhance water infiltration and drainage efficiency, providing valuable insights for designing low-impact development strategies in flood-prone regions.

Haselbach, Liv [Lamar Univ., Beaumont, TX (United ↗
DOE OSTI2015

Tumor-infiltrating lymphocyte activity is enhanced in tumors with low IL-10 production in HBV-induced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers and can be induced by chronic HBV infection. The role of HBV-specific immune responses in mediating tumorigenesis and HCC prognosis is debated. The effect of intratumoral microenvironment on tumor-infiltrating lymphocytes (TILs) is also unclear. Here, we examined resected tumor tissue from 36 patients with HBV-induced HCC. We categorized study cohort based on ex vivo IL-10 secretion by tumor cells into high IL-10-secreting (Hi10) and low IL-10-secreting (Lo10) groups, and found that the Lo10 group was less sensitive to TLR ligand stimulation. TILs from the Lo10 group contained higher frequencies of HBV-specific IFN-g-producing cells and total IFN-g-producing cells, and possessed higher proliferative capacity. Moreover, the proliferative capacity of TILs from the Hi10 group was negatively correlated with IL-10 secretion from tumor cells. Together, our data demonstrated that low IL-10-producing capacity in HBV-induced HCC tumors is associated with enhanced TIL activity. - Highlights: • We examined intratumoral IL-10 production in HBV-induced HCC. • We grouped HCC tumors into Hi10 and Lo10 groups based on their IL-10 production. • Lo10 groups had better IFN-g response by TILs. • Lo10 groups had better TIL proliferative capacity. • Lo10 group tumor cells were refractory to TLR ligand stimulation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Decreased serum estrogen improves fat graft retention by enhancing early macrophage infiltration and inducing adipocyte hypertrophy

Highlights: • Decreased estrogen improved fat graft retention, while increased estrogen failed. • Decreased estrogen elevated early macrophage infiltration. • Decreased estrogen induced adipocyte hypertrophy and tissue fibrosis. • Increased estrogen improved angiogenesis and increased stem cell density. • Increased estrogen suppressed the early inflammation. Fat grafting is a commonly used procedure; however, the mechanisms that regulate graft outcomes are not clear. Estrogen has been associated with vascularization, inflammation and fat metabolism, yet its role in fat grafting is unclear.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Novel theranostic agent for PET imaging and targeted radiopharmaceutical therapy of tumour-infiltrating immune cells in glioma

Background: Malignant gliomas are deadly tumours with few therapeutic options. Although immunotherapy may be a promising therapeutic strategy for treating gliomas, a significant barrier is the CD11b + tumour-associated myeloid cells (TAMCs), a heterogeneous glioma infiltrate comprising up to 40% of a glioma's cellular mass that inhibits anti-tumour T-cell function and promotes tumour progression. A theranostic approach uses a single molecule for targeted radiopharmaceutical therapy (TRT) and diagnostic imaging; however, there are few reports of theranostics targeting the tumour microenvironment. Methods: Utilizing a newly developed bifunctional chelator, Lumi804, an anti-CD11b antibody (αCD11b) was readily labelled with either Zr-89 or Lu-177, yielding functional radiolabelled conjugates for PET, SPECT, and TRT. Findings: 89 Zr/ 177 Lu-labeled Lumi804-αCD11b enabled non-invasive imaging of TAMCs in murine gliomas. Additionally, 177 Lu-Lumi804-αCD11b treatment reduced TAMC populations in the spleen and tumour and improved the efficacy of checkpoint immunotherapy. Interpretation: 89 Zr- and 177 Lu-labeled Lumi804-αCD11b may be a promising theranostic pair for monitoring and reducing TAMCs in gliomas to improve immunotherapy responses.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Infiltrated Sr 0.9 Y 0.1 CoO 2.5+δ nanoparticles as a cathode material for solid oxide fuel cells operated at 450–650 °C

Catalytically active cathode materials are highly desirable for the development of low-temperature solid oxide fuel cells (LT-SOFCs). In the present study, we report the performance of a high-loading Sr 0.9 Y 0.1 CoO 2.5+δ (SYC10) nanoparticles (NPs) as a catalytic cathode infiltrated in Ce 0.8 Gd 0.2 O 2-δ (GDC) backbones for LT-SOFCs and the use of a low-loading SYC10 NPs as a catalyst for promoting the performance of a commercial cathode. The loading and calcination temperature of SYC10 NPs were systematically optimized to achieve the lowest area-specific polarization resistance at ≤650 °C. A significant reduction in polarization resistance of commercial LSCF cathode by SYC NPs has also been demonstrated at 650 °C.

08 HYDROGEN↗