BIOM-06. MOLECULAR SIGNATURES UNDERLIE THE DISTINCT FAILURE PATTERNS OF MALIGNANT GLIOMAS

BACKGROUND Malignant gliomas exhibit varied failure patterns upon recurrence; however, genomic backgrounds of these distinct phenotypes have not been evaluated. We aimed to explore the genomic traits associated with distinct failure patterns in malignant glioma patients. METHODS This study involved 272 malignant glioma patients. Failure pattern was defined for the spatial relationship between recurrent tumor and the original tumor as follows: local recurrence (LR), remote recurrence, leptomeningeal seeding (LMC), and combined failure pattern. Molecular characteristics underlying different failure patterns were investigated for the mutation profile, copy number variation (CNV), and transcriptomic signatures. RESULTS Local recurrence was the most prominent failure pattern (62.9%), followed by combined recurrence (22.8%). Multivariate Cox regression analysis confirmed failure pattern as one of the independent prognostic factors. Patients with combined failure patterns exhibited the worst prognoses, whereas patients with remote recurrence exhibited the most favorable outcomes (median overall survival = 11.4 and 25.2 months, respectively). In IDH1-wild type glioblastoma (GBM) patients, TERT and PIK3CA mutation were significantly associated with the development of combined failure pattern and leptomeningeal seeding, respectively (p-value=0.015 & p-value=0.004, respectively). Transcriptomic analysis exhibited that inter-neuronal synaptic transmission was enriched in GBMs with combined failure pattern and this finding was further validated in proteomic analysis; neuronal myelination and synaptic transmission-related pathways were upregulated in GBMs which exhibited combined failure pattern. CONCLUSIONS Collectively, we demonstrated that the inherent molecular characteristics of the tumors might contribute to the eventual relapse patterns; tracking their evolutionary pathways may unravel novel therapeutic vulnerabilities of these tumors.

Extending a Homogenized Model for Characterizing Multidirectional Jellyroll Failure in Prismatic Lithium-Ion Batteries

Lithium-ion batteries have been widely used in electric vehicles but may cause severe internal short circuit during extreme intrusion-type accidents. A well-defined homogenized model of battery or jellyroll is necessary for safety assessment and design on large-scale structure level. In our previous study, the jellyroll of prismatic lithium-ion battery cell shows anisotropic mechanical behavior and failure tolerance. For homogenized characterization of jellyroll, in the present paper, the user subroutine of a constitutive model taking anisotropy into account is implanted into Abaqus finite element analysis software, which is capable of capturing the force versus displacement responses along different loading directions before jellyroll failure. To extend the capability of the homogenized model, five single-parameter failure criteria and two combined failure criteria are examined in predicting the failure onsets in jellyroll along different directions. The result proves the combined failure criteria is competent to correctly predict the multidirectional failure onsets compared with the single-parameter ones.

The SHEAR BEHAVIOR OF REINFORCED CONCRETE BEAMS STRENGTHENED BY CFRP STRIPS

In this research, (12) normal reinforced concrete beams are used with dimensions (110*10*20) cm, the compressive strength for all specimens is 30 MPa. Longitudinal steel is deformed bars 2Ø12mm with Ø6 mm transverse reinforcement which is deformed bars also for different spacing 5 cm, 10 cm and 15 cm. After casting the specimens and removing them from the molds, they left for about 28 days. They tied by CFRP strips with different shapes of tying (tied, inclined and X- shaped). They are all testing with two points load by a hydraulic machine for determining (Pu, P cr, maximum deflection and modes of failure) and compared among their results with the specimens without CFRP strips. From the experimental program, the excellent behavior of the specimens with the X-shaped strips especially with the Pu which is 70% increment and maximum deflection is 39% decrement. The addition of CFRP strips as a tying material helps to increase the strength of concrete and bearing against loads also, changes and decreases the flexural and shear failure and combined failure.

EPEN-50. THE MANAGEMENT AND TREATMENT OF PEDIATRIC SPINAL CORD EPENDYMOMA: RESULTS FROM A COLLABORATIVE INTERNATIONAL MULTI-INSTITUTIONAL REVIEW

PURPOSE Pediatric Spinal cord ependymoma (SCE) is rare, and the management is often heterogeneous across centers. We evaluated the impact of clinical, pathologic, and treatment-related factors on outcomes in a multi-institutional, international cohort. METHODS SCE patients age <21 years were reviewed across 5 institutions. We utilized nonparametric descriptive statistics, survival, and recursive partitioning analysis (RPA) to examine patient, tumor, histopathologic and treatment characteristics, failure pattern, and cause of death. RESULTS 125 patients were identified, 18 (14.4%) with metastases. Initial surgery was GTR, and STR in 44, 56% of patients respectively. Histology was grade 1, 2, and 3 in 55, 17.7 and 23.2% respectively. 55 patients with initial GTR were observed (52.7%) or irradiated (43.6%); 60 patients had STR and were observed (40%) or irradiated (60%). The 7-year event-free (EFS) and overall survival (OS) was 60% (95% CI 51.5–71.4) and 79% (95% CI 71.1–87.8) respectively. STR and metastasis increased the hazard for death [HR 1.87, 95% CI 1.02–3.57, p=0.05 (vs. GTR)] and [HR 2.28, 95% CI 1.1–5.2, p=0.048 (vs. localized)] respectively. Across 43 failures, local failure predominated (48.8%). Distant and combined failure occurred in 30.2 and 13.9% respectively. Adjuvant RT offered a 20% absolute improvement (vs. observation) in EFS at 5 years regardless of extent of resection. RPA identified thoracic (vs. non-thoracic), grade (1 & 3 vs. 2), STR (vs. GTR) and metastases as determinants of inferior EFS. CONCLUSIONS Tumor and treatment-related factors are predictive of EFS. OS is favorable despite diverse schema and frequent distant failures.

Numerical simulation of failure mechanism in screw anchors under static tension

Concrete screw anchors under tension commonly fail in a combined (pullout and concrete breakout) mode; however, currently, there is no mechanistic model to predict the load in this mode. Finite element models of screw anchors can help understand the mechanism of the combined mode and predict the ultimate strength in this mode ( Ncomb). In this study, finite element models were developed and validated by 37 tests of screw anchors in three different diameters ( d) and two effective embedment depths ( hef) per diameter. The finite element models were used to identify the combined failure mode and to compare with the experimental load–displacement curves and Ncomb. An additional 119 simulations including variations of d, hef, and concrete compressive strength [Formula: see text] were generated. Based on the results, Ncomb was found significantly related to [Formula: see text], [Formula: see text], and d0.35. A prediction model for Ncomb was developed which showed an overall good fit using a total of 93 experimental data.

Investigation of a combined failure mode for screw anchors under tension

A modified concrete capacity design method is available to predict the ultimate tensile strength ( Nu) of screw anchors. Screw anchors commonly fail in a combination of concrete breakout and pullout modes. This combined mode is not distinguished from the breakout mode in the modified concrete capacity design method, which may cause confusions to designers. To investigate the Nu of the combined mode ( Ncomb), this study included 144 unconfined tension tests on screw anchors from three manufacturers in three diameters and two effective embedment depths ( hef) per diameter. Approximately 80% of the tested anchors failed in the combined mode. The differences in Ncomb among the three manufacturers were insignificant despite their varied thread design. Ncomb was found to be linearly correlated to the parameter hef 1.3 but was found independent of the anchor diameter. A regression model was developed to specifically predict Ncomb. The model showed a good fit with the test results.