Intermetallic-matrix composites are attractive alternatives to carbon / carbon and ceramic / ceramic composites for applications up to 1,600°C. Recent work on the intermetallic compounds MoSi 2 and Ti Si 3 has included determination of t~eir mechanical properties and deformation behavior, selection of thermodynamically compatible high-strength and ductile reinforcements, and strengthening and toughening mechanisms in silicide-matrix composites for high-temperature service. Figure 1. Melting temperature as a function of density for high-temperature intermetallic compounds. The indicated T m is the melting temperature which gives 0.8 T m = 1 ,600°C.

SummaryBackground This study investigated the mechanisms involved in development of donor-specific antibody (DSA) and/or C4d-negative transplant glomerulopathy (TGP) by allograft gene expression profiles using microarrays.Design, Setting, Participants, & Measurements This cohort study was conducted in kidney transplant recipients. Patients were eligible for inclusion if they required a clinically indicated biopsy at any time point after their transplant. They were then classified according to their histopathology findings and DSA and C4d results. Eighteen chronic antibody-mediated rejection (CAMR), 14 DSA+/C4d2 TGP, 25 DSA2/C4d2 TGP, and 47 nonspecific interstitial fibrosis/tubular atrophy (IFTA) biopsy specimens were identified. In a subset of patients from the study population, biopsy specimens in each group and normal transplant kidney specimens were analyzed with Affymetrix Human Gene 1.0 ST Arrays.Results The mean sum score of glomerulitis and peritubular capillaritis increased from 0.2860.78 in IFTA specimens to 0.7560.85 in DSA2/C4d2 TGP specimens, 1.7161.49 in DSA+/C4d2/TGP specimens, and 2.1161.74 in CAMR specimens (P,0.001). During a median follow-up time of 2 (interquartile range, 1.4-2.8) years after biopsy, graft loss was highest in CAMR specimens (27.8%) compared to IFTA specimens (8.5%), DSA+/C4d2 TGP specimens (14.3%), and DSA2/C4d2 TGP specimens (16%) (P=0.01). With use of microarrays, comparison of the gene expression profiles of DSA2/C4d2 TGP specimens with glomerulitis + peritubular capillaritis scores . 0 to normal and IFTA biopsy specimens revealed higher expression of quantitative cytotoxic T cell-associated transcripts (QCAT). However, both CAMR and DSA+/C4d2 TGP specimens had higher expression of not only QCAT but also IFN-g and rejection-induced, constitutive macrophage-associated, natural killer cell-associated, and DSA-selective transcripts. Endothelial cell-associated transcript expression was upregulated only in CAMR biopsy specimens.Conclusions These results suggested that DSA+/C4d2 TGP biopsy specimens may be classified as CAMR. In contrast, DSA2/C4d2 TGP specimens showed increased cytotoxic T cell-associated transcripts, suggesting T cell activation as a mechanism of injury.

The diagnostic criteria for antibody-mediated rejection (AMR) are continuously evolving. Here we investigated the clinical and molecular significance of different Banff microvascular inflammation (MVI) scores in transplant kidney biopsies. A total of 356 patients with clinically indicated kidney transplant biopsies were classified into three groups based on MVI scores of 0, 1, 2, or more for Groups 1-3, respectively. Gene expression profiles were assessed using arrays on a representative subset of 93 patients. The incidence of donor-specific anti-HLA antibodies was increased from 25% in Group 1 to 36% in Group 2 and to 54% in Group 3. Acute and chronic AMR were significantly more frequent in Group 3 (15% and 35%) compared with the Group 2 (3% and 15%) and Group 1 (0% and 5%), respectively. Gene expression profiles showed increased interferon-γ and rejection-induced, cytotoxic and regulatory T-cell, natural killer cell-associated and donor-specific antibody (DSA)-selective transcripts in Group 3 compared with Groups 1 and 2. There was no significant difference in gene expression profiles between the Groups 1 and 2. Increased intragraft expression of DSA-selective transcripts was found in the biopsies of C4d- Group 3 patients. Thus, an MVI score of 2 or more was significantly associated with a histological diagnosis of acute and chronic antibody-mediated rejection. Hence, increased intragraft DSA-selective gene transcripts may be used as molecular markers for AMR, especially in C4d- biopsies.

The effect of self-irradiation damage on the local structure of δ-Pu, PuAl 2 , PuGa 3 , and other Pu intermetallics has been determined for samples stored at room temperature using the extended x-ray absorption finestructure (EXAFS) technique. These measurements indicate that the intermetallic samples damage at a similar rate as indicated in previous studies of PuCoGa 5 . In contrast, δ-Pu data indicate a much slower damage accumulation rate. To explore the effect of storage temperature and possible room temperature annealing effects, we also collected EXAFS data on a δ-Pu sample that was held at less than 32 K for a two month period. This sample damaged much more quickly. In addition, the measurable damage was annealed out at above only 135 K. Data from samples of δ-Pu with different Ga concentrations and results on all samples collected from different absorption edges are also reported. These results are discussed in terms of the vibrational properties of the materials and the role of Ga in δ-Pu as a network former.

The standard 4.4-cm angiocatheter is likely to be unsuccessful in 50% (95% confidence interval = 40.7-59.3%) of trauma patients on the basis of body habitus. In light of its low predicted success, the standard method for treatment of tension pneumothorax by prehospital personnel deserves further consideration.