Extremely high strength and work hardening ability in a metastable high entropy alloy.

Design of multi-phase high entropy alloys uses metastability of phases to tune the strain accommodation by favoring transformation and/or twinning during deformation. Inspired by this, here we present Si containing dual phase Fe42Mn28Co10Cr15Si5 high entropy alloy (DP-5Si-HEA) exhibiting very high strength (1.15 GPa) and work hardening (WH) ability. The addition of Si in DP-5Si-HEA decreased the stability of f.c.c. (γ) matrix thereby promoting pronounced transformation induced plastic deformation in both as-cast and grain refined DP-5Si-HEAs. Higher yet sustained WH ability in fine grained DP-5Si-HEA is associated with the uniform strain partitioning among the metastable γ phase and resultant h.c.p. (ε) phase thereby resulting in total elongation of 12%. Hence, design of dual phase HEAs for improved strength and work hardenability can be attained by tuning the metastability of γ matrix through proper choice of alloy chemistry from the abundant compositional space of HEAs.

Enhanced strength and ductility in a friction stir processing engineered dual phase high entropy alloy.

The potential of high-entropy alloys (HEAs) to exhibit an extraordinary combination of properties by shifting the compositional regime from the corners towards the centers of phase diagrams has led to worldwide attention by material scientists. Here we present a strong and ductile non-equiatomic HEA obtained after friction stir processing (FSP). A transformation-induced plasticity (TRIP) assisted HEA with composition Fe50Mn30Co10Cr10 (at.%) was severely deformed by FSP and evaluated for its microstructure-mechanical property relationship. The FSP-engineered microstructure of the TRIP HEA exhibited a substantially smaller grain size, and optimized fractions of face-centered cubic (f.c.c., γ) and hexagonal close-packed (h.c.p., ε) phases, as compared to the as-homogenized reference material. This results in synergistic strengthening via TRIP, grain boundary strengthening, and effective strain partitioning between the γ and ε phases during deformation, thus leading to enhanced strength and ductility of the TRIP-assisted dual-phase HEA engineered via FSP.

MAGNETOCALORIC RESPONSE OF NON-STOICHIOMETRIC Ni2MnGa ALLOYS AND THE INFLUENCE OF CRYSTALLOGRAPHIC TEXTURE.

Currently, there is significant interest in magnetocaloric materials for solid state refrigeration. In this work, polycrystalline Heusler alloys belonging to the Ni2+xMn1-xGa family, with x between 0.08 and 0.24, were evaluated for the purpose of finding composition(s) with an enhanced magnetocaloric effect (MCE) close to room temperature. Differential scanning calorimetry (DSC) was successfully used to screen alloy composition for simultaneous magnetic and structural phase transformations; this coupling needed for a giant MCE. The alloy with x = 0.16 showed an excellent match of transformation temperatures and exhibited the highest magnetic entropy change, ΔSM, in the as-annealed state. Furthermore, the MCE increased by up to 84 % with a 2 Tesla (T) field change when the samples were thermally cycled through the martensite to austenite transformation temperature while held under a constant mechanical load. The highest ΔSM measured for our x = 0.16 alloy for a 2 T magnetic field change was -18 J/kg-K. Texture measurements suggest that preferential orientation of martensite variants contributed to the enhanced MCE in the stress-assisted thermally cycled state.

Mortality after acute renal failure: models for prognostic stratification and risk adjustment.

To adjust adequately for comorbidity and severity of illness in quality improvement efforts and prospective clinical trials, predictors of death after acute renal failure (ARF) must be accurately identified. Most epidemiological studies of ARF in the critically ill have been based at single centers, or have examined exposures at single time points using discrete outcomes (e.g., in-hospital mortality). We analyzed data from the Program to Improve Care in Acute Renal Disease (PICARD), a multi-center observational study of ARF. We determined correlates of mortality in 618 patients with ARF in intensive care units using three distinct analytic approaches. The predictive power of models using information obtained on the day of ARF diagnosis was extremely low. At the time of consultation, advanced age, oliguria, hepatic failure, respiratory failure, sepsis, and thrombocytopenia were associated with mortality. Upon initiation of dialysis for ARF, advanced age, hepatic failure, respiratory failure, sepsis, and thrombocytopenia were associated with mortality; higher blood urea nitrogen and lower serum creatinine were also associated with mortality in logistic regression models. Models incorporating time-varying covariates enhanced predictive power by reducing misclassification and incorporating day-to-day changes in extra-renal organ system failure and the provision of dialysis during the course of ARF. Using data from the PICARD multi-center cohort study of ARF in critically ill patients, we developed several predictive models for prognostic stratification and risk-adjustment. By incorporating exposures over time, the discriminatory power of predictive models in ARF can be significantly improved.

Portal vein opacification during ERCP in patients with pancreatitis.

We report two cases of portal vein visualization during ERCP in patients with pancreatitis, one from inadvertent cannulation of the superior mesenteric vein, and in the other, through a preexisting fistula. Prompt recognition of this potentially significant event will obviate confusion and unnecessary prolongation of the procedure.

Depiction of diaphragmatic muscle slips on supine plain radiographs: a sign of pneumoperitoneum.

PURPOSE: To describe the diaphragm muscle slip sign, a previously unreported finding of pneumoperitoneum on plain radiographs. MATERIALS AND METHODS: Diaphragmatic muscle slips were observed on supine plain abdominal (n = 6) or recumbent frontal chest (n = 3) radiographs in nine patients. Computed tomographic (CT) confirmation was available in six patients; free air was depicted on upright chest radiographs in the other three patients. RESULTS: Muscle slips of the costal portion of the diaphragm were depicted in the right upper quadrant as they indented the adjacent air-filled peritoneal cavity. On supine radiographs, these discrete muscle bundles appeared as two or three large, arcuate interfaces or as bands of increased opacity of similar dimensions, with their long axes directed vertically. These smoothly marginated bundles were parallel to the dome and converged superomedially. On the CT scans, the costal muscle slips were clearly defined as bands or small peripheral triangles impinging on the parietal peritoneum. CONCLUSION: Depiction of the undersurface of the long costal muscle slips of the diaphragm on supine plain radiographs is a sign of pneumoperitoneum.

Visualization of the extrahepatic segment of the ligamentum teres: a sign of free air on plain radiographs.

PURPOSE: To assess visualization of the extrahepatic segment of the ligamentum teres on plain radiographs, the ligamentum teres sign, which is an indicator of pneumoperitoneum. MATERIALS AND METHODS: The ligamentum teres was recognized in 12 patients with pneumoperitoneum. Findings from supine radiographs were correlated with those from oblique radiographs and computed tomograms. RESULTS: The extrahepatic segment of the ligamentum teres, which extended between the umbilicus and the ligamentum teres notch at the inferior border of the liver, was visualized on supine radiographs. The ligamentum teres appeared in the right upper quadrant as an obliquely oriented, straight, or slightly arcuate interface with a sharply demarcated inferolateral margin or as a similarly positioned, well-defined band of soft tissue of varying length. The falciform ligament was also seen in six of the 12 patients as a long, thin line that ran vertically to the right of the midline and joined the ligamentum teres caudally near or at the umbilicus. Even though there were other signs of pneumoperitoneum in all cases, the ligamentum teres sign was the most prominent in three cases. CONCLUSION: Visualization of the extrahepatic segment of the ligamentum teres on supine radiographs requires the anterior accumulation of extraluminal, intraperifoneal gas and is another sign of moderate to massive amounts of free air.

Transpyloric spread of gastric tumors: comparison of adenocarcinoma and lymphoma.

OBJECTIVE: Our objective was to determine the relative frequency of transpyloric tumor spread in gastric antral carcinoma and lymphoma. MATERIALS AND METHODS: We reviewed the medical records of 127 cases of pathologically proven gastric malignant tumors, including 102 carcinomas and 25 lymphomas, over a 10-year period. The antrum had carcinoma in 64 cases and lymphoma in 15. We reviewed upper gastrointestinal barium studies and correlated the findings of transpyloric tumor extension with the results of surgery, pathology, and endoscopy. RESULTS: Tumor extension into the duodenal bulb occurred in 16 (25%) of 64 patients with carcinoma and in six (40%) of 15 patients with lymphoma of the gastric antrum. Transpyloric spread of antral carcinoma as revealed by barium study was much more common in our series than has been stated in the literature. CONCLUSION: Duodenal invasion of an antral carcinoma is not rare. Because of the higher incidence of carcinoma, transpyloric spread of gastric tumor as revealed by barium studied should not by itself suggest the diagnosis of lymphoma.

Wedge-shaped intrahepatic cholangiocarcinoma: MRI-pathologic correlation.

On magnetic resonance imaging (MRI) studies, wedge-shaped areas of signal abnormality noted in association with liver lesions have been attributed to secondary phenomena and are said to be substantially larger than the actual tumor. We describe the MRI and pathological appearance of a wedge-shaped cholangiocarcinoma. In cases where therapy might be affected, biopsy of wedge-shaped MRI abnormalities associated with hepatic malignancy should be considered for accurate tumor staging.

Palliation of esophageal cancer with a self-expanding, silicone-covered stent and a technique for stent retrieval.

Most patients with carcinoma of the esophagus present with progressive, unrelenting dysphagia, malnutrition, and weight loss. Palliation is the primary treatment, since these patients are not candidates for curative surgical resection. Surgery, radiotherapy, and endoscopic modalities have been used for palliation. Recently, self-expanding, metallic stents have been used with considerable success. This type of stent can dislodge into the stomach during or after deployment. We report an approach to retrieve an expandable, silicone-coated stent using a double-channel endoscope, an esophageal dilating balloon, and a polypectomy snare.

Nasopancreatic drainage: a novel approach for treating internal pancreatic fistulas and pseudocysts.

Internal pancreatic fistulas are rare but debilitating complications of chronic pancreatitis. Fistulous tracts from the pancreatic duct to the peritoneal or pleural cavities have been treated by medical therapy and surgical management, with success rates of 41% and 89%, respectively. Endoscopic stent placement for internal and external pancreatic fistulas has also been shown effective. We report on three patients with histories of chronic alcohol abuse and pancreatitis. Two patients presented with dyspnea and pleuritic chest pain. Imaging studies revealed pleural effusions, and endoscopic retrograde cholangiopancreatography (ERCP) demonstrated a patent fistulous tract from the pancreatic duct to the pleural cavity in each patient. Chemical analysis of the pleural fluid indicated pancreatic origin. The third patient, who had left-upper-quadrant abdominal pain and a small pleural effusion, had a large noncommunicating pseudocyst adjacent to the stomach. Nasopancreatic drains, along with chest tube drainage, were placed in the patients with pancreatic pleural fistulas. The patient with the pseudocyst received nasocystic drainage via the stomach. Drainage was measured until closure of the fistulas or cyst. Additionally, simply by injecting contrast medium, we were able to monitor the closure of fistulas without ERCP. The fistulas closed within 7 days, and the pseudocyst resolved within 14 days. Following discharge, all three patients were pain free, without evidence of recurrent fistulas or pseudocyst. In conclusion, the use of nasopancreatic/cyst drainage is an effective and convenient way to treat internal, communicating collections and pseudocysts of pancreatic origin. Furthermore, this method provides a simple means of assessing closure of fistulas and pseudocysts.

Evidence suggesting a role for phospholipase C isozyme, PLC-delta 1 in corticomedullary osmotic gradients in rat kidneys.

We determined the distributional patterns of phospholipase C isozymes within the rat kidneys. PLC-beta1 was localized in the inner medulla at the highest degree followed by the inner stripe of the outer medulla, the cortex and the outer stripe of the outer medulla. PLC-gamma1 was distributed homogeneously along the corticomedullary axis. PLC-delta1 showed gradual increase from the cortex to the inner medulla. Tissue osmotic gradients were measured using 4 slices, resulting in gradual increase from the cortex to the inner medulla. The pattern of PLC-delta1 appeared very similar to the osmotic gradient in the kidney. The results suggest that the distinct patterns of the PLC isozymes may be associated with different signal transduction pathways along the corticomedullary axis and PLC-delta1 may play a role in the osmoregulation of the medullary region.

CT in patients with blunt abdominal trauma: clinical significance of intraperitoneal fluid detected on a scan with otherwise normal findings.

OBJECTIVE: The purpose of this study was to determine the clinical significance of intraperitoneal fluid seen on CT scans with otherwise normal findings in patients with blunt abdominal trauma. MATERIALS AND METHODS: We retrospectively analyzed the CT scans of 60 patients with blunt abdominal trauma who had scans showing normal findings except for the presence of intraperitoneal fluid. The location of the fluid was determined (pouch of Douglas, pelvis, paracolic gutters, mesentery, Morison's pouch, perihepatic or perisplenic spaces). The amount of fluid in each location was categorized as minimal, moderate, or marked. The total volume of fluid in each patient was estimated as small (+1), intermediate (+2), or large (+3) on the basis of the sum of the amount of fluid in the individual peritoneal locations. The amount and location of fluid were compared between patients who required exploratory laparotomy and those who were managed conservatively. RESULTS: In most patients, the total fluid volume was small (44 patients, 73%) as opposed to intermediate (11 patients, 18%) or marked (five patients, 8%). Thirty-seven patients had fluid in one location, 12 patients had fluid in two locations, and 11 patients had fluid in three or more locations. Intraperitoneal fluid tended to accumulate in the pouch of Douglas (67%) and Morison's pouch (33%). Patients requiring laparotomy had a higher total fluid volume score compared with the patients managed conservatively (2.2 versus 1.3, p < .002) and had larger amounts of fluid in the upper abdomen. Laparotomy was required in only one patient (2%) who had a small amount of fluid compared with three patients (27%) with intermediate and two patients (40%) with marked amounts. Mesenteric and/or bowel injuries were noted in all six patients at laparotomy. One patient had a small superficial liver laceration that was not diagnosed with CT. No other injuries to the solid viscera were missed on the scans. Two of the four patients with mesenteric fluid seen on the CT scan had mesenteric lacerations found during surgery, and the remaining two did well with conservative management. CONCLUSION: Patients with blunt abdominal trauma who have small amounts of intraperitoneal fluid as the sole abnormality shown by CT may generally be treated conservatively. However, patients with even a small quantity of mesenteric fluid may benefit from peritoneal lavage to help exclude bowel or mesenteric injury. Intermediate and large amounts of fluid are less common as the sole CT abnormality but have a higher likelihood of being associated with bowel or mesenteric injury.

Varices in portal hypertension: evaluation with CT.

The portosystemic collateral channels that can develop in portal hypertension are numerous, widespread, and varied in appearance. The reported prevalences of varices at each anatomic site vary according to the diagnostic modality used. Dynamic computed tomography (CT) performed with a bolus of contrast material demonstrates collateral vessels with exquisite detail. On CT scans, varices appear as well-defined found, tubular, or serpentine structures that are smooth, have homogeneous attenuation, and enhance with contrast material to the same degree as adjacent vessels. In 60 consecutive patients with varices and evidence of cirrhosis, the most common portosystemic collateral channels were coronary venous collateral vessels in the lesser omentum, seen in 80% of cases. Esophageal, paraumbilical, abdominal wall, perisplenic, retrogastric, paraesophageal, omental, retroperitoneal-paravertebral, and mesenteric varices were also found, along with spontaneous splenorenal and gastrorenal shunts. Knowledge of the CT appearance and the prevalence of varices at each anatomic site will improve diagnostic accuracy.

Focal enhancement of the liver on CT: a sign of SVC obstruction.

We describe a case in which a focus of intense contrast enhancement within the anterior aspect of the medial segment of the left lobe of the liver was detected on abdominal CT. This led to the diagnosis of clinically unsuspected superior vena cava obstruction.

Inflammatory fibroid polyp of the esophagus in an HIV-infected individual: case study.

We report an unusual case of a large esophageal inflammatory fibroid polyp in a man infected with the human immunodeficiency virus complaining of dysphagia. Barium studies and computed tomography demonstrated a long, submucosal-appearing, distal esophageal mass which extended into a hiatal hernia. Inflammatory fibroid polyps should be considered in the differential diagnosis of submucosal and polypoid esophageal masses, although distinctive radiographic features are not found.

Idiopathic localized dilatation of the ileum in adults: findings on barium studies.

OBJECTIVE: Idiopathic localized dilatation of the ileum is a rare entity characterized by a sharply demarcated segmental dilatation of the small bowel that is in line with the lumen. It is probably congenital in origin. Although more commonly diagnosed in children, it presents in adults as occult gastrointestinal (GI) bleeding or less often with abdominal pain. On pathologic examination, the mucosa may be ulcerated, but otherwise the wall is relatively normal. We analyzed the radiographic findings in nine previously unreported cases of this condition in adults. MATERIALS AND METHODS: Collaborative efforts resulted in the collection of nine cases from multiple institutions. In five cases, an enteroclysis had been performed; in three, a conventional small bowel series had been performed; and in one, the lesion was seen on a barium enema with reflux into the ileum. The mean age of patients was 52 years. In seven cases, pathologic correlation was available. In the other two patients, long-term clinical follow-up and repeat studies confirmed the diagnosis. Resected specimens showed a thin but otherwise normal wall with normal ganglion cells and nerve plexuses. Ulceration was noted in six of the seven resected cases. Two cases contained heterotopic gastric mucosa. GI bleeding and/or anemia was the most common (77%) presenting symptom. Abdominal pain and/or obstruction was present in slightly less than half the patients (44%). RESULTS: Lesions were 6-21 cm long and 4-13 cm wide, and all were located in the ileum. The dilated segments were bilobate in three cases, multilobate in three, spherical in two, and tubular in the other. The dilated area was always in line with the long axis of the bowel, not projecting to the side. No surrounding masses were seen. Except in three patients in whom ulcers were noted, the mucosa was normal. CONCLUSION: Idiopathic localized dilatation of the ileum should be suspected whenever a sharply demarcated area of lobulated small bowel dilatation is seen in a middle-aged patient with occult GI bleeding. The axial orientation distinguishes this condition from small bowel diverticula (including Meckel's). The lack of surrounding mass, mucosal irregularity, hypermotility, or fistulae help differentiate it from other causes of small bowel dilatation.