Effect of Particle Strength on SiCp/Al Composite Properties with Network Architecture Design.

Recent works have experimentally proven that metal matrix composites (MMCs) with network architecture present improved strength-ductility match. It is envisaged that the performance of architecturally designed composites is particularly sensitive to reinforcement strength. Here, reinforcing particles with various fracture strengths were introduced in numerical models of composites with network particle distribution. The results revealed that a low particle strength (1 GPa) led to early-stage failure and brittle fracture. Nevertheless, a high particle strength (5 GPa) delayed the failure behavior and led to ductile fracture at the SiC/Al-Al macro-interface areas. Therefore, the ultimate tensile strengths (UTS) of the network SiC/Al composites increased from 290 to 385 MPa, with rising particle strength from 1 to 5 GPa. Based on the composite property, different particle fracture threshold strengths existed for homogeneous (~2.7 GPa) and network (~3.7 GPa) composites. The higher threshold strength in network composites was related to the increased stress concentration induced by network architecture. Unfortunately, the real fracture strength of the commercial SiC particle is 1-2 GPa, implying that it is possible to select a high-strength particle necessary for efficient network architecture design.

Discovery and Correction of Spurious Low Platelet Counts due to EDTA-Dependent Pseudothrombocytopenia.

BACKGROUND: Ethylene diamine tetraacetic acid dependent pseudothrombocytopenia (EDTA-PTCP) is a laboratory artifact that may lead to unnecessary evaluation and treatment of patients. The purpose of this article is to discuss how to identify EDTA-PTCP and correct spurious low platelet counts in clinical laboratories. METHODS: We use two criteria to screen for platelet aggregation: (1) an abnormal platelet count in EDTA-treated blood from a patient lacking clinical signs of a platelet disorder, and (2) an instrument flag for platelet clumps. EDTA-PTCP was confirmed by microscopic examination for platelet agglutination and by platelet counts that corrected with citrate sample. In addition, the time course of EDTA-PTCP was investigated in samples from 26 patients anticoagulated with EDTA-K2 and sodium citrate. Amikacin (5 mg/ml) was added to tubes with EDTA-K2 or sodium citrate from seven additional cases in order to confirm its dissociative effect on platelet aggregation. RESULTS: In our laboratory, the overall incidence of EDTA-PTCP was approximately 0.09%; and the duration was between 2 weeks and 6 months. EDTA-PTCP was time-dependent and occurred as early as 10 min after sample collection. Weaker agglutination could also occur in most corresponding citrate-treated samples. The dissociative effect of amikacin on platelet agglutination was case-specific and not concentration-dependent. CONCLUSIONS: The method of screening for platelet clumping with the help of XE5000 images is convenient. The decline in the platelet count is related to the length of time and the intensity of chelation. Amikacin supplement is not always effective for correcting platelet counts in vitro.

[Correlation factors of ethylenediaminetetraacetic acid-dependent pseudothrombocytopenia in cancer patients].

OBJECTIVE: To investigate the correlation factors of ethylenediaminetetraacetic acid-dependent pseudothrombocytopenia (EDTA-PTCP) in cancer patients. METHODS: The potential correlation factors of EDTA-PTCP such as gender, age, case history, tumor types, therapeutic drugs and duration of EDTA-PTCP from cancer patients were analyzed based on the patient records from October 2007 to September 2009 at our cancer center. RESULTS: A total of 49 EDTA-PTCP cases from a pool of 55 000 cancer patients were collected. No correlation was found with gender (male 49.0%, female 51.0%), concurrent hypertension (20.4%)/diabetes (10.2%) or cancer types (1 - 11 cases each type). EDTA-PTCP appeared at pre-therapy (n = 13) and post-therapy (n = 36). Eleven cases (30.6%) were chemotherapy, 5 cases (13.9%) were radiotherapy plus chemotherapy, 15 case (41.7%) were tumor resection, 5 cases (13.9%) were interventional therapy in 36 patients whose EDTA-PTCP appeared post-therapy. The most frequency use in chemotherapy patients was dexamethasone (87.5%, 14/16), and in surgery patients was penicillin antibiotics (75.0%, 15/20). And its frequency was once (n = 18) and more than twice (n = 31). If the subjects were divided into 2 groups of non-treatment plus surgery and chemotherapy plus intervention on the basis of treatment course, there was a significant difference between two groups in proportion of patients whose duration of EDTA-PTCP ≤ 2 weeks (89.3% vs 47.6%, χ(2) = 10.22, P < 0.01). CONCLUSIONS: The incidence of EDTA-PTCP in cancer patients may be associated with therapeutic drugs, but not probably with gender, concurrent hypertension/diabetes, tumor types or therapeutic regimens. Duration of EDTA-PTCP may be associated with the treatment course.