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Among the various forms of material damage, delamination due to drilling is one of the major concerns in machining a composite laminate. The thrust force has been cited as the primary cause of the delamination. The analysis for multidirectional composite laminates is based on linear elastic fracture mechanics (LEFM), classical bending plate theory and the mechanics of composites. This paper presents a general closed-form mechanical model for predicting the critical thrust force at which delamination is initiated at different ply locations. Good correlation is observed between the model and the experimental results.

Heterogeneous nuclear ribonucleoprotein K (hnRNP K) mediates antiapoptotic activity in part by inducing downstream antiapoptotic genes. To systematically identify hnRNP K targets in nasopharyngeal carcinoma (NPC), affymetrix chips were used to identify genes that were both overexpressed in primary NPC and downregulated by hnRNP K knockdown in NPC-TW02 cells. The resulting gene set included the antiapoptotic gene, FLIP, which was selected for further study. In cells treated with hnRNP K siRNA, TRAIL-induced apoptosis was enhanced and the FLIP protein level was reduced. Promoter, DNA pull-down and chromatin-immunoprecipitation assays revealed that hnRNP K directly interacts with the poly(C) element on the FLIP promoter, resulting in transcriptional activation. Through iTRAQ-mass spectrometric identification of proteins differentially associated with the poly(C) element or its mutant, nucleolin was determined to be a cofactor of hnRNP K for FLIP activation. Furthermore, FLIP was highly expressed in tumor cells, and this high-level expression was significantly correlated with high-level hnRNP K expression (P ¼ 0.002) and poor overall survival (P ¼ 0.015) as examined in 67 NPC tissues. A multivariate analysis confirmed that FLIP was an independent prognostic factor for NPC. Taken together, these findings indicate that FLIP expression is transcriptionally regulated by hnRNP K and nucleolin, and may be a potential prognostic and therapeutic marker for NPC. Heterogeneous nuclear ribonucleoprotein K (hnRNP K) belongs to the hnRNP family of proteins. The members of this family interact directly with DNA and RNA through their K-homology domains and regulate gene expression at multiple levels, including transcription, RNA splicing, RNA stability and translation.1-2 The expression of hnRNP K has been shown to be aberrantly increased in numerous cancers, [3][4][5][6] and we recently reported that high-level hnRNP K expression is correlated with poorer overall survival (OS) and decreased metastasis-free survival among nasopharyngeal carcinoma (NPC) patients.5 Our findings were consistent with those from clinical correlation studies in oral squamous cell carcinoma 4 and prostate cancer. HnRNP K is a nucleocytoplasmic shuttling protein that is primarily located in the nucleus for transcriptional regulation. However, cytoplasmic accumulation of hnRNP K through ERK-mediated phosphorylation of hnRNP K serines-284 and -353 has been reported in cervical carcinoma HeLa, 7 chronic myelogenous leukemia 8 and NPC 9 cells. The tumorigenic activity of hnRNP K appears to be conferred through its ability to increase proliferation, 10 antiapoptotic effects, 9 clonogenic potential 8 and metastasis. 11 These functions may be due, at least in part, to the ability of hnRNP K to upregulate the c-myc, 8,12 thymidine phosphorylase (TP) 9 and eIF4E 10 genes through transcriptional or post-transcriptional regulation. However, the full spectrum of targets regulated by hnRNP K has not as yet been systematically examined.The acquisition of resistance to ...