FCC to BCC transformation-induced plasticity based on thermodynamic phase stability in novel V10Cr10Fe45CoxNi35-x medium-entropy alloys.

We introduce a novel transformation-induced plasticity mechanism, i.e., a martensitic transformation from fcc phase to bcc phase, in medium-entropy alloys (MEAs). A VCrFeCoNi MEA system is designed by thermodynamic calculations in consideration of phase stability between bcc and fcc phases. The resultantly formed bcc martensite favorably contributes to the transformation-induced plasticity, thereby leading to a significant enhancement in both strength and ductility as well as strain hardening. We reveal the microstructural evolutions according to the Co-Ni balance and their contributions to a mechanical response. The Co-Ni balance plays a leading role in phase stability and consequently tunes the cryogenic-temperature strength-ductility balance. The main difference from recently-reported metastable high-entropy dual-phase alloys is the formation of bcc martensite as a daughter phase, which shows significant effects on strain hardening. The hcp phase in the present MEA mostly acts as a nucleation site for the bcc martensite. Our findings demonstrate that the fcc to bcc transformation can be an attractive route to a new MEA design strategy for improving cryogenic strength-ductility.

Cryogenic strength improvement by utilizing room-temperature deformation twinning in a partially recrystallized VCrMnFeCoNi high-entropy alloy.

The excellent cryogenic tensile properties of the CrMnFeCoNi alloy are generally caused by deformation twinning, which is difficult to achieve at room temperature because of insufficient stress for twinning. Here, we induced twinning at room temperature to improve the cryogenic tensile properties of the CrMnFeCoNi alloy. Considering grain size effects on the critical stress for twinning, twins were readily formed in the coarse microstructure by cold rolling without grain refinement by hot rolling. These twins were retained by partial recrystallization and played an important role in improving strength, allowing yield strengths approaching 1 GPa. The persistent elongation up to 46% as well as the tensile strength of 1.3 GPa are attributed to additional twinning in both recrystallized and non-recrystallization regions. Our results demonstrate that non-recrystallized grains, which are generally avoided in conventional alloys because of their deleterious effect on ductility, can be useful in achieving high-strength high-entropy alloys.

Enteral patch repair of the vena caval defect: an experimental study.

Three adult mongrel dogs were aseptically prepared and celiotomy performed under general anesthesia. The inferior vena cava below the renal veins was dissected and a 5.0 cm segment of the vena cava was clamped with Satinsky vena cava clamp. A segment of the anterior wall, 7.0 x 14.0 mm, of the vena cava was resected and the defect was sutured to the serosa of the adjacent small bowel wall with 3-0 or 4-0 Dexon running sutures. The dogs were kept alive for 4 to 6 weeks postoperatively and the animals were reexplored and the vena cavogram was taken through a catheter in the common iliac vein using 60 per cent Urograffin. All three dogs were confirmed to have patent vena cava and the en-bloc segment of the vena cava and the small bowel was removed for the pathological specimen. The histological section of the specimen revealed a newly formed intimal layer covering the surface of the small bowel serosa patching the vena caval defect and this intimal layer was covered by a single layer of endothelial cells on the surface. With this result, the possibility of maintaining the full function of the vena cava following the repair of its defect with the enteral patch is confirmed. We do not have any clinical cases to be presented at this time, but this method may well be one of the applicable ways of repairing vena caval defects, although it may not be the best one.

Expression of HLA-DR antigen in large bowel carcinoma.

One hundred large bowel carcinomas were studied immunohistochemically with regard to expression of HLA-DR antigen (DR). One or two sections from each tumor including surrounding normal mucosa were examined by a semiquantitative counting system for tumor cells and mucosal and stromal infiltrates of lymphocytes and mononuclear cells (MNCs) with DR expression and the results were applied Chi-square test. The rate of presence of DR positive (DR+) lymphocytes in lymphoid nodules and DR+ lymphocytes/ MNC in the adjacent mucosa and stroma in DR+ carcinoma (50%) was higher (P < 0.01) than in DR- carcinoma (21.9%). Thirty-six carcinomas (36%) were DR+. Three (75%) out of 4 DR+ poorly differentiated carcinomas and six (20%) out of 30 DR+ moderately differentiated carcinomas showed homogeneously strong DR+ expression. There was tendency for poorly differentiated carcinoma to be more homogeneous DR+ expression. According to Dukes' stage, four (80%) out of 5 carcinomas in Dukes' stage D were DR-. An increased infiltration of lymphocytes/MNCs into adjacent mucosa and stroma in large bowel carcinomas is possibly related with DR expression by carcinoma. From the results of this study, we postulated as follows: 1) DR+ tumor cells may act as antigen-presenting cells, 2) They may have an inhibitory effect for distant metastasis, 3) Poorly differentiated carcinoma expressed more DR+ homogeneously.

Military parachute mishap fatalities: a retrospective study.

Military parachuting is relatively safe. Most injuries involve vertebral bodies or the lower extremity, and fatalities are rare. We studied 49 military parachute accident facilities occurring during 1964-1989. Causes of the accidents included accidental deployment of reserve parachute in aircraft, static line failures and entanglements, equipment (canopy) failures, in-air collisions, landing injuries, drowning, and dragging. Rarely, preexisting illness such as coronary artery disease caused or contributed to an accident. Pathologic findings revealed a high proportion of deceleration and blunt force injuries: cardiac, aortic and liver laceration, and skull, pelvic and extremity fractures. Isolated head injury, strangulation, and post traumatic pulmonary embolus were occasionally noted. Toxicological examination demonstrated contributing factors such as alcohol intoxication or antihistamine use in a small number of cases. Background investigations, scene inspections, autopsy and toxicology studies all yielded important data or pertinent negatives during investigations. We propose an investigation protocol.

The Armed Forces medical examiner system: a change for the better.

The armed forces of the United States of America maintain bases throughout the United States as well as in many other countries. The current situation with regard to the investigation of the approximately 2,500 non-combat deaths each year as well as other deaths occurring on military reservations in complex, confusing, and inconsistent at best. Under existing federal law, base commanders can order an autopsy on all active-duty personnel as well as on anyone dying within an area of exclusive federal jurisdiction. Base commanders unfamiliar with the law are often unwilling to order autopsies, and bodies may go to their graves leaving serious questions, such as cause and manner of death, unanswered. In an effort to rectify this situation, as well as to provide consistency in death investigations in the United States military, the Office of the Armed Forces Medical Examiner (AFME) is being established. The AFME will have its headquarters at The Armed Force Institute of Pathology (AFIP) in Washington, DC. All deaths coming under its jurisdiction will be reported in a timely manner and, when required, authorization for autopsy will be granted from the AFME. Regional deputy medical examiners will be appointed to perform autopsies and on-scene investigations. All cases and case materials will be reviewed and retained by the office of the AFME at AFIP. The quality of death investigation will be improved within the United States military by adoption of this system.

Comparison of the terminal ballistics of full metal jacket 7.62-mm M80 (NATO) and 5.56-mm M193 military bullets: a study in ordnance gelatin.

Great controversy has surrounded the replacement of the 7.62-mm caliber by the reduced 5.56-mm caliber as the standard U.S. military rifle. Although its relevance to human wounding can be debated, the terminal ballistics of military small arms in ordnance gelatin remains a convenient medium for comparative testing. In the present study, 7- by 10- by 24-in. (18 by 25 by 61 cm) blocks of 20% ordnance gelatin were fired upon from a range of 19 ft (6 m) under high-speed cinemagraphic surveillance. The tendency of the M193 5.56-mm full metal jacket projectile to break up in soft tissue simulant was confirmed as a fundamental difference from the 7.62-mm M80 NATO ball.