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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Overexpressing circular RNA hsa{sub c}irc{sub 0}002052 impairs osteosarcoma progression via inhibiting Wnt/β-catenin pathway by regulating miR-1205/APC2 axis

Circular RNAs (circRNAs) are a novel class of noncoding RNAs, whose importance in cancer has been gradually acknowledged. However, the functions of circRNAs in tumorigenesis have not been fully understood. In the present study, we identified a novel circRNA hsa{sub c}irc{sub 0}002052 significantly downregulated in osteosarcoma (OS) tissues and cell lines. Moreover, we found that hsa{sub c}irc{sub 0}002052 could act as a biomarker to indicate the prognosis of OS patients. Functionally, we showed that hsa{sub c}irc{sub 0}002052 overexpression significantly suppressed OS cell proliferation, migration and invasion while promoting apoptosis in vitro. Similarly, in vivo assay indicated that ectopic expression of hsa{sub c}irc{sub 0}002052 impaired OS cell growth. In terms of mechanism, we found that hsa{sub c}irc{sub 0}002052 inhibited miR-1205 while miR1205 targeted APC2, a negative regulator of Wnt/β-catenin signaling pathway. By releasing the inhibition of miR-1205 on APC2 expression, hsa{sub c}irc{sub 0}002052 suppressed the activation of Wnt/β-catenin signaling pathway, leading to attenuated OS progression. Taken together, our study for the first time revealed a suppressive circRNA hsa{sub c}irc{sub 0}002052 involved in OS progression. Our study suggested hsa{sub c}irc{sub 0}002052/miR-1205/APC2/Wnt/β-catenin axis might be a potential target for OS therapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Circular RNA circ-CBFB promotes proliferation and inhibits apoptosis in chronic lymphocytic leukemia through regulating miR-607/FZD3/Wnt/β-catenin pathway

Circular RNA (circRNA) belongs to the non-coding RNA family and is involved in various human cancers, such as lung cancer and colorectal cancer. Nevertheless, whether circRNA expression is related to chronic lymphocytic leukemia (CLL) progression remains largely unclear. In our study, we investigated the role of circ-CBFB in CLL. We found that circ-CBFB was markedly overexpressed in CLL cells compared to normal controls. Furthermore, we found that circ-CBFB could serve as a diagnostic and prognostic biomarker for CLL patients. We also explored the physiological function of circ-CBFB. We found that circ-CBFB knockdown significantly suppressed CLL cell proliferation, arrested cell cycle progression, and induced cellular apoptosis. In terms of its mechanism, we identified circ-CBFB as a sponge of miR-607, which targeted FZD3. By inhibiting miR-607 availability, circ-CBFB promoted FZD3 expression, leading to the activation of the Wnt/β-catenin pathway and consequent CLL progression. Taken together, our findings revealed that the circ-CBFB/miR-607/FZD3/Wnt/β-catenin regulatory signaling cascade contributes to CLL progression.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Circular RNA HIPK3 promotes gallbladder cancer cell growth by sponging microRNA-124

Highlights: • circHIPK3 is upregulated in established and primary human gallbladder cancer cells. • circHIPK3 siRNA inhibits human gallbladder cancer cell survival and proliferation. • Ectopic circHIPK3 over-expression promotes gallbladder cancer cell proliferation. • circHIPK3 targets miR-124 in gallbladder cancer cells. • circHIPK3 upregulation correlates with miR-124 downregulation in gallbladder cancer tissues. Recent studies have implied that circHIPK3, an abundant circular RNA (circRNA), participates in tumorigenesis and cancer progression. Its expression and potential functions in human gallbladder cancer were examined in this study. We show that circHIPK3 is upregulated in human gallbladder cancer cells. But its level is low in gallbladder epithelial cells. circHIPK3 silencing by targeted siRNA potently inhibited survival and proliferation of established and primary human gallbladder cancer cells, while inducing cell apoptosis. Conversely, ectopic over-expression of circHIPK3 can further promote cancer cell proliferation. In gallbladder cancer cells, circHIPK3 sponged the tumor-suppressive microRNA-124 (miR-124) to sequester and inhibit its activity, thereby leading to increased expression of miR-124 targets, including ROCK1 (rho-associated protein kinase 1) and CDK6 (rho-associated protein kinase). Ectopic over-expression of miR-124 b y a lentiviral vector mimicked and abolished actions by circHIPK3 siRNA in gallbladder cancer cells. At last, we show that circHIPK3 is upregulated in human gallbladder cancer tissues, which is correlated with miR-124 downregulation and ROCK1-CDK6 upregulation. Together, we conclude that circHIPK3 promotes gallbladder cancer cell growth possibly by sponging miR-124. The over-expressed circHIPK3 could be a novel therapeutic target and diagnosis marker of human gallbladder cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Circ-UBR5: An exonic circular RNA and novel small nuclear RNA involved in RNA splicing

Highlights: • Low expression of circ-UBR5 in NSCLC was significantly related with tumor poor differentiation. • A highly efficient strategy for finding specific circRNA binding proteins using HuprotTM Protoarray was first be presented. • Circ-UBR5 could bind splicing regulatory factors QKI, and NOVA1 and U1 snRNA in the nucleus. • Our research first revealed the potential function of a non-functional phenotype circRNA in NSCLC cells. Circular RNAs (circRNAs) are class of non-coding RNAs formed by back-splicing events as loops, and could be found in all types of organisms. They play important and diverse roles in cell development, growth, and tumorigenesis, but functions of the majority of circRNAs remain enigmatic. Particularly functional phenotypes of great majority of circRNAs are not obvious. Here we randomly selected a circRNA circ-UBR5, which has no obvious functional phenotype in non-small cell lung cancer (NSCLC) cells from our previous research findings, to explore its potential function in cells. Differential expression of circ-UBR5 was detected in paired samples of tumorous tissues and adjacent nontumorous tissues from 59 patients with NSCLC by real-time quantitative reverse transcription-polymerase chain reactions (qRT-PCRs). Results showed circ-UBR5 expression was significantly downregulated in NSCLC tissues (p (p = 0.00126), suggesting circ-UBR5 might serve as an index of NSCLC differentiation. Our findings indicated circ-UBR5 could bind splicing regulatory factor QKI, KH domain containing RNA binding (QKI) and NOVA alternative splicing regulator 1 (NOVA1) and U1 small nuclear RNA (snRNA) in the nucleus, revealing circ-UBR5 might be a novel snRNA involved in RNA splicing regulatory process. Moreover, we first presented a highly efficient strategy for finding specific circRNA binding proteins using Human Protein Microarray (Huprot™ Protoarray).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Circular RNA HIPK3 regulates human lens epithelial cells proliferation and apoptosis by targeting the miR-193a/CRYAA axis

Highlights: • CircRNA sequencing reveals 26 up-regulated and 75 down-regulated circRNAs in ARC. • CircHIPK3 is down-regulated in all three subtypes of ARC. • CircHIPK3 knockdown affects the cellular function in primary cultured HLECs. • CircHIPK3 exerts its role via modulation of circHIPK3/miR-193a/CRYAA axis in HLECs. Circular RNAs (circRNAs) are a novel class of non-coding RNAs generated from back splicing. Accumulating evidence has demonstrated their vital regulation in several biological processes and ocular diseases. However, the role of circRNAs in age-related cataract (ARC), the leading cause of visual impairment worldwide, is still unknown. CircRNA sequencing reveals that 101 circRNAs are differentially expressed between the capsules of transparent and ARC lenses, including 75 down-regulated circRNAs and 26 up-regulated circRNAs transcripts. Eight of 10 differentially expressed circRNAs are further verified by quantitative RT-PCRs. One highly conserved circRNA, circHIPK3, is significantly down-regulated in all cortical, nuclear and posterior subcapsular subtypes of ARC. The silencing of circHIPK3, but not HIPK3 mRNA, significantly accelerates apoptosis development upon oxidative stress and decreases cell viability and proliferation in primary cultured human lens epithelial cells (HLECs). The expression of α-SMA and vimentin was downregulated, while the expression of E-cadherin and ZO-1was upregulated, suggesting the repression of epithelial-mesenchymal transition after circHIPK3 knockdown. CircHIPK3 silencing increases miR-193a expression. miR-193a regulates CRYAA expression by targeting the binding site within the 3′UTR. Moreover, miR-193a decreases the viability and proliferation, and increases the apoptosis of HLECs upon oxidative stress. This study suggests that circRNAs are the potential regulators in cataractogenesis. CircHIPK3 regulates HLECs function through miR-193a-mediated CRYAA expression. This finding would provide a novel insight into the pathogenesis of ARC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Circular RNA circ{sub 0}001649 acts as a prognostic biomarker and inhibits NSCLC progression via sponging miR-331-3p and miR-338-5p

Accumulating evidence documented the key functions of circular RNAs (circRNAs) in various malignancies. However, the study regarding the involvement of circRNAs in non-small cell lung cancer (NSCLC) has just begun. In the present study, qRT-PCR was used to determine the expression of circ{sub 0}001649 in NSCLC tissues and cells. Its clinical significance was further assessed by Fisher's exact test, Kaplan-Meier analysis and Cox regression model. Additionally, loss-of-function and gain-of-function experiments were carried out to detect the functional role of circ{sub 0}001649 in cell proliferation, migration and invasion. Furthermore, animal study was performed to confirm the in vitro results. Importantly, luciferase reporter assay was induced to reveal the underlying mechanism of circ{sub 0}001649. As a result, circ{sub 0}001649 was decreased in NSCLC tissues and cells and this downregulation is correlated with advanced TNM stage, positive lymph node metastasis and unfavorable prognosis. Additionally, circ{sub 0}001649 inhibited cell growth and metastasis both in vitro and in vivo. In mechanism, circ{sub 0}001649 was identified as the sponge of miR-331-3p and miR-338-5p. Moreover, the biological functions of circ{sub 0}001649 is partly dependent on its regulation on miR-331-3p and miR-338-5p. Collectively, this study suggested that circ{sub 0}001649/miR-331-3p/miR-338-5p regulatory signaling might be a potential target for NSCLC therapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Upregulated circular RNA circ{sub 0}016760 indicates unfavorable prognosis in NSCLC and promotes cell progression through miR-1287/GAGE1 axis

Non-small cell lung cancer (NSCLC) is an aggressive malignancy with increasing worldwide incidence and is characterized by dismal prognosis due to its early recurrence and metastasis. Accumulating evidence documented that aberrantly expressed circular RNAs (circRNAs) are critically involved in tumorigenesis. In the current study, we focused on a novel circRNA, circ{sub 0}016760 in NSCLC. qRT-PCR was carried out to determine the expression level of circ{sub 0}016760 in tissue samples and cell lines. The clinical value of circ{sub 0}016760 was also investigated. The functions of circ{sub 0}016760 was explored by CCK-8, colony formation, flow cytometry, Transwell and animal experiments. Luciferase reporter assays were conducted to investigate the association between circ{sub 0}016760 and miR-1287 and miR-1287 and GAGE1. We found that circ{sub 0}016760 was enhanced in NSCLC tissues and cells and the upregulation of circ{sub 0}016760 is associated with advanced TNM stages, lymph node metastasis and adverse prognosis in NSCLC patients. Moreover, circ{sub 0}016760 could significantly promote cell growth and metastatic properties and inhibit cell apoptosis in NSCLC cells. In mechanism, circ{sub 0}016760 functioned as a sponge for miR-1287 and regulated the expression of GAGE1. Subsequently, functional assays illustrated that the oncogenic properties of circ{sub 0}016760 is partly attribute to the regulation of miR-1287/GAGE1 axis. In summary, circ{sub 0}016760/miR-1287/GAGE1 signaling might play vital roles in the tumorigenesis and progression of NSCLC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Overexpression of circular RNA circ{sub 0}01569 indicates poor prognosis in hepatocellular carcinoma and promotes cell growth and metastasis by sponging miR-411-5p and miR-432-5p

Emerging evidence indicated that abnormally expressed circular RNAs (circRNAs) are critically involved in tumorigenesis and development of several cancers. However, the study relevant to the relationship between circRNAs and hepatocellular carcinoma (HCC) is rare. In this study, the expression of circ{sub 0}01569 in HCC tissue specimens and cells were determined by qRT-PCR. The clinical relevance of circ{sub 0}01569 was also analyzed. In addition, loss-of-function and gain-of-function assays were conducted to explore the biological functions of circ{sub 0}01569. Furthermore, tumor formation and lung metastasis studies were induced to confirm the in vitro data. Mechanistically, bioinformatics analysis and luciferase reporter assays were conducted to illustrate the underlying mechanism of circ{sub 0}01569. The results indicated that circ{sub 0}01569 was overexpressed in HCC tissue samples and cells. This overexpression is correlated with larger tumor size, advanced TNM stages and unfavorable prognosis in the patients with HCC. Additionally, circ{sub 0}01569 significantly facilitated HCC cell growth, migration and invasion. The animal studies further confirmed the in vitro results. More importantly, circ{sub 0}01569 could directly sponge miR-411-5p and miR-432-5p. The oncogenic functions of circ{sub 0}01569 is partially dependent on its regulation on miR-411-5p and miR-432-5p. In summary, circ{sub 0}01569/miR-411-5p/miR-432-5p regulatory signaling might be a rational HCC-related therapeutic target.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Global identification of circular RNAs in chronic myeloid leukemia reveals hsa{sub c}irc{sub 0}080145 regulates cell proliferation by sponging miR-29b

Highlights: • A large number of circRNAs aberrantly expressed in chronic myeloid leukemia. • Top 20 aberrantly expressed interacted with leukemia-associated miRNAs. • hsa{sub c}irc{sub 0}080145 knockdown significantly suppressed CML cell proliferation. • hsa{sub c}irc{sub 0}080145 acts as an miR-29b sponge in CML. Circular RNAs (circRNAs) are a class of non-coding RNAs that participate in various biological processes and disease pathogenesis. However, the role of circRNAs in chronic myeloid leukemia (CML) remains largely unknown. In this study, high-throughput sequencing was performed to explore the expression profile of circRNAs in CML patients for the first time, and a large number of differentially expressed circRNAs were identified. In addition, we constructed potential circRNA-miRNA interaction networks in CML, including a detailed hsa{sub c}irc{sub 0}080145-mediated competing endogenous RNA (ceRNA) regulatory network. Furthermore, functional experiments demonstrated that hsa{sub c}irc{sub 0}080145 knockdown significantly suppressed CML cell proliferation and hsa{sub c}irc{sub 0}080145 regulated CML cell proliferation by acting as an miR-29b sponge.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Circular orientation fluorescence emitter imaging (COFEI) of rotational motion of motor proteins

Single-molecule fluorescence polarization technique has been utilized to detect structural changes in biomolecules and intermolecular interactions. Here we developed a single-molecule fluorescence polarization measurement system, named circular orientation fluorescence emitter imaging (COFEI), in which a ring pattern of an acquired fluorescent image (COFEI image) represents an orientation of a polarization and a polarization factor. Rotation and pattern change of the COFEI image allow us to find changes in the polarization by eye and further values of the parameters of a polarization are determined by simple image analysis with high accuracy. We validated its potential applications of COFEI by three assays: 1) Detection of stepwise rotation of F{sub 1}-ATPase via single quantum nanorod attached to the rotary shaft γ; 2) Visualization of binding of fluorescent ATP analog to the catalytic subunit in F{sub 1}-ATPase; and 3) Association and dissociation of one head of dimeric kinesin-1 on the microtubule during its processive movement through single bifunctional fluorescent probes attached to the head. These results indicate that the COFEI provides us the advantages of the user-friendly measurement system and persuasive data presentations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

The circular RNA circ-ITCH suppresses ovarian carcinoma progression through targeting miR-145/RASA1 signaling

Highlights: • A broad down-regulation of circ-ITCH and a worse prognosis were found in OC patients. • Circ-ITCH inhibits the cell viability and motility by CCK8, cell cycle, wound healing and invasion assay. • Circ-ITCH inhibits the tumorigenesis ability in xenograft NOD mice in vivo. • Circ-TCH acts as a ceRNA role of circ-ITCH through sponging miR-145 and up-regulation of RASA1 expression. As the leading cause of death for gynecological cancers, ovarian cancer (OC) ranks fifth overall for cancer-related death among women. Emerging evidence has indicated that circular RNA (circRNA), recognized as functional non-coding transcripts in eukaryotic cells, may be involved in many physiological or pathological processes. It was reported that circ-ITCH is downregulated in multi cancers and serves as a powerful tumor suppressor among through a competing endogenous RNA (ceRNA) pathway. However, the existence and the role of circ-ITCH in OC was not reported. Here, we found a broad down-regulation of circ-ITCH in OC tissues and cells, which correlates with a worse prognosis in OC patients. Functional studies suggest that circ-ITCH overexpression inhibits the cell viability and motility by CCK8, cell cycle, wound healing assay and invasion assay. It also inhibits the tumorigenesis ability in xenograft NOD mice in vivo. Mechanically, we demonstrated that circ-TCH acts as a ceRNA to sponge miR-145, increases the level of RASA1, and inhibits the malignant progression of OC cells via the circ-ITCH-miR-145-RASA1 axis in vitro and in vivo. Taken together, our findings provide a novel tumor suppressive role regarding circ-ITCH function in the malignant progression of OC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Circular RNA HIPK3 exerts oncogenic properties through suppression of miR-124 in lung cancer

Highlights: • CircHIPK3 is upregulated in human lung cancer cells. • CircHIPK3 siRNA inhibits lung cancer cell survival and proliferation. • CircHIPK3 overexpression promotes lung cancer cell survival and proliferation. • CircHIPK3 regulates expression miR-124 and its targets in lung cancer cells. • CircHIPK3 upregulation correlates with miR-124 downregulation in human lung cancer tissues. The current study tested the expression and potential functions of circular RNA HIPK3 (circHIPK3) in human lung cancer. Our results show that circHIPK3 expression is upregulated in established (A549 line) and primary human lung cancer cells, when compared to its low level in the lung epithelial cells. siRNA-mediated silencing of circHIPK3 potently inhibited survival and proliferation of lung cancer cells, but inducing significant apoptosis activation. Contrarily, forced overexpression of circHIPK3 by a lentiviral construct promoted lung cancer cell survival and proliferation. CircHIPK3 acted as a microRNA-124 (miR-124) sponger and regulated the expression of miR-124 mRNA targets, including SphK1, CDK4 and STAT3, in lung cancer cells. Transfection of miR-124 inhibitor significantly inhibited circHIPK3 siRNA-induced lung cancer cell death and apoptosis. At last, we show that circHIPK3 levels are upregulated in human lung cancer tissues, correlated with miR-124 downregulation. The miR-124 targets (SphK1, STAT3 and CDK4) are upregulated in lung cancer tissues. Together, we propose that circHIPK3 promotes lung cancer cell progression possibly by sponging miR-124. These observations indicate a possible novel therapeutic strategy involving circHIPK3-miR-124 pathway against lung cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Mining metatranscriptomes reveals a vast world of viroid-like circular RNAs

Viroids and viroid-like covalently closed circular (ccc) RNAs are minimal replicators that typically encode no proteins and hijack cellular enzymes for replication. The extent and diversity of viroid-like agents are poorly understood. We developed a computational pipeline to identify viroid-like cccRNAs and applied it to 5,131 metatranscriptomes and 1,344 plant transcriptomes. The search yielded 11,378 viroid-like cccRNAs spanning 4,409 species-level clusters, a 5-fold increase compared to the previously identified viroid-like elements. Within this diverse collection, we discovered numerous putative viroids, satellite RNAs, retrozymes, and ribozy-like viruses. Diverse ribozyme combinations and unusual ribozymes within the cccRNAs were identified. Self-cleaving ribozymes were identified in ambiviruses, some mito-like viruses and capsid-encoding satellite virus-like cccRNAs. The broad presence of viroid-like cccRNAs in diverse transcriptomes and ecosystems implies that their host range is far broader than currently known, and matches to CRISPR spacers suggest that some cccRNAs replicate in prokaryotes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Detonation diffraction in a circular arc geometry of the insensitive high explosive PBX 9502

We describe the details of an unconfined insensitive high explosive (PBX 9502) circular arc section experiment, in which, after a transient period, a detonation sweeps around the arc with constant angular speed. The arc section is sufficiently wide that the flow along the centerline of the arc section remains two-dimensional. Data includes time-of-arrival diagnostics of the detonation along the centerline inner and outer arc surfaces, which is used to obtain the angular speed of the steadily rotating detonation. We also obtain the lead shock shape of the detonation as it sweeps around the arc. Reactive burn model simulations of the PBX 9502 arc experiment are then conducted to establish the structure of the detonation driving zone, i.e. the region enclosed between the detonation shock and flow sonic locus (in the frame of the steady rotating detonation). It is only the energy released in this zone which determines the speed at which the steady detonation sweeps around the arc. We show that the sonic flow locus of the detonation driving zone largely lies at the end of, or within, the fast reaction stage of the PBX 9502 detonation, with the largest section of the detonation driving zone lying close to the inner arc surface. In conclusion, we also demonstrate that the reactive burn model provides a good prediction of both the angular speed of the detonation wave and the curved detonation front shape.

42 ENGINEERING↗
DOE OSTI2015

Transient thermal protection of film covering circular aperture by sublimation and weak decomposition

Unwanted heating of sensitive surfaces in harsh thermal environments can be prevented by precise application of sacrificial materials such as sublimation layers and pyrolyzing films. The use of sublimation for the protection of circular polyimide membranes subjected to brief (~100 ms) heating by infrared radiation and hot (6000 K) inert gas convection is analyzed. Selection of sublimation material and sublimation layer and membrane thickness is considered with emphasis on providing sufficient thermal protection yet negligible unwanted material remaining at the end of a specified heating period. Though the analysis here is general, the motivation is protection of the polyimide films covering the laser entrance holes on IFE (inertial fusion energy) hohlraums being injected into the hot gas (xenon) protecting IFE reactor chambers. Furthermore, both one and two dimensional thermal models are used to develop a robust thermal concept. Sensitivity analyses (SA) methods are exercised to show where the design may be vulnerable and which input parameters have the greatest effect on performance and likelihood of success. For the design and conditions considered, methane sublimating layers are probably preferred over xenon or pentane.

42 ENGINEERING↗
DOE OSTI2015

Displacement Fields and Self-Energies of Circular and Polygonal Dislocation Loops in Homogeneous and Layered Anisotropic Solids

There are large classes of materials problems that involve the solutions of stress, displacement, and strain energy of dislocation loops in elastically anisotropic solids, including increasingly detailed investigations of the generation and evolution of irradiation induced defect clusters ranging in sizes from the micro- to meso-scopic length scales. Based on a two-dimensional Fourier transform and Stroh formalism that are ideal for homogeneous and layered anisotropic solids, we have developed robust and computationally efficient methods to calculate the displacement fields for circular and polygonal dislocation loops. Using the homogeneous nature of the Green tensor of order -1, we have shown that the displacement and stress fields of dislocation loops can be obtained by numerical quadrature of a line integral. In addition, it is shown that the sextuple integrals associated with the strain energy of loops can be represented by the product of a pre-factor containing elastic anisotropy effects and a universal term that is singular and equal to that for elastic isotropic case. Furthermore, we have found that the self-energy pre-factor of prismatic loops is identical to the effective modulus of normal contact, and the pre-factor of shear loops differs from the effective indentation modulus in shear by only a few percent. These results provide a convenient method for examining dislocation reaction energetic and efficient procedures for numerical computation of local displacements and stresses of dislocation loops, both of which play integral roles in quantitative defect analyses within combined experimental–theoretical investigations.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Spherical indentation of a freestanding circular membrane revisited: Analytical solutions and experiments

Because of the development of novel micro-fabrication techniques to produce ultra-thin materials and increasing interest in thin biological membranes, in recent years, the mechanical characterization of thin films has received a significant amount of attention. To provide a more accurate solution for the relationship among contact radius, load and deflection, the fundamental and widely applicable problem of spherical indentation of a freestanding circular membrane have been revisited. The work presented here significantly extends the previous contributions by providing an exact analytical solution to the governing equations of Föppl–Hecky membrane indented by a frictionless spherical indenter. In this study, experiments of spherical indentation has been performed, and the exact analytical solution presented in this article is compared against experimental data from existing literature as well as our own experimental results.

36 MATERIALS SCIENCE↗
DOE OSTI2022

AI and extreme scale computing to learn and infer the physics of higher order gravitational wave modes of quasi-circular, spinning, non-precessing black hole mergers

We use artificial intelligence (AI) to learn and infer the physics of higher order gravitational wave modes of quasi-circular, spinning, non precessing binary black hole mergers. We trained AI models using 14 million waveforms, produced with the surrogate model NRHybSur3dq8, that include modes up to $\ell$ ≤ 4 and (5,5), except for (4,0) and (4,1), that describe binaries with mass-ratios $\textit{q}$ ≤ 8, individual spins $s^z_{\{1,2\}} \in$[–0.8,0.8], and inclination angle $θ \in$ [0,π]. Our probabilistic AI surrogates can accurately constrain the mass-ratio, individual spins, effective spin, and inclination angle of numerical relativity waveforms that describe such signal manifold. We compared the predictions of our AI models with Gaussian process regression, random forest, k-nearest neighbors, and linear regression, and with traditional Bayesian inference methods through the PyCBC Inference toolkit, finding that AI outperforms all these approaches in terms of accuracy, and are between three to four orders of magnitude faster than traditional Bayesian inference methods. Our AI surrogates were trained within 3.4 hours using distributed training on 1,536 NVIDIA V100 GPUs in the Summit supercomputer.

79 ASTRONOMY AND ASTROPHYSICS↗