Intercritical annealing to achieve a positive strain-rate sensitivity of mechanical properties and suppression of macroscopic plastic instabilities in multi-phase medium-Mn steels.

This study investigates the high strain-rate tensile properties of a cold-rolled medium-Mn steel (Fe-12Mn-3Al-0.05C % in mass fraction) designed to have a multi-phase microstructure and positive strain-rate sensitivity. At the intercritical annealing temperature of 585 °C, increasing the annealing time from 0.5 h to 8 h increased the phase volume fraction of ultrafine-grained (UFG) austenite from 2% to 35% by reversion. The remainder of the microstructure was composed of UFG ferrite and recovered α'-martensite (the latter resembles the cold-rolled state). Servo hydraulic tension testing and Kolsky-bar tension testing were used to measure the tensile properties from quasi-static strain rates to dynamic strain rates ( ε ˙ = 10 - 4 s - 1 to ε ˙ = 10 3 s - 1 ). The strain-rate sensitivities of the yield strength (YS) and ultimate tensile strength (UTS) were positive for both annealing times. Tensile properties and all non-contact imaging modalities (infrared imaging and digital image correlation) indicated an advantageous suppression of Lüders bands and Portevin Le Chatelier (PLC) bands (a critical challenge in multi-phase medium-Mn steel design) due to the unique combination of microstructural constituents and overall composition. Fracture surfaces of specimens annealed for 0.5 h showed some instances of localized cleavage fracture (approximately 30 µm wide areas and lath-like ridges). Specimens annealed for 8 h maintained a greater product of strength and elongation by at least 2.5 GPa % (on average for each strain rate). The relevant processing-structure-property relationships are discussed in the context of recommendations for design strategies concerning multi-phase steels such that homogeneous deformation behavior and positive strain-rate sensitivities can be achieved.

Experimental and numerical study of mechanical properties of multi-phase medium-Mn TWIP-TRIP steel: influences of strain rate and phase constituents.

In the current work we investigate the room temperature tensile properties of a medium-Mn twinning- and transformation-induced plasticity (TWIP-TRIP) steel from quasi-static to low-dynamic strain rates ( ε ˙ = 10 - 4 s - 1 to ε ˙ = 10 2 s - 1 ). The multi-phase microstructure consists of coarse-grained recovered α' -martensite (inherited from the cold-rolled microstructure), multiple morphologies of ultrafine-grained (UFG) austenite (equiaxed, rod-like and plate-like), and equiaxed UFG ferrite. The multi-phase material exhibits a positive strain-rate sensitivity for yield and ultimate tensile strengths. Thermal imaging and digital image correlation allow for in situ measurements of temperature and local strain in the gauge length during tensile testing, but Lüders bands and Portevin Le Chatelier bands are not observed. A finite-element model uses empirical evidence from electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), plus constitutive equations to dissect the microstructural influences of grain size, dislocation density and TWIP-TRIP driving forces on tensile properties. Calibration of tensile properties not only captures the strain rate sensitivity of the multi-phase TWIP-TRIP steel, but also provides opportunity for a complete parametric analysis by changing one variable at a time (phase fraction, grain size, strain-induced twin fraction and strain-induced ε-martensite fraction). An equivalent set of high-rate mechanical properties can be matched by changing either the austenite phase fraction or the ratio of twinning vs. transformation to ε-martensite. This experimental-computational framework enables the prediction of mechanical properties in multi-phase steels beyond the experimental regime by tuning variables that are relevant to the alloy design process.

Donor site morbidity after microvascular medial femoral condylar flap procurement for facial reconstruction.

The medial femoral condyle (MFC) flap is considered an ideal graft for bone reconstructions. This study was performed to evaluate donor site knee joint function and scar appearance after MFC flap procurement. Adult patients who had undergone facial reconstruction with an MFC flap between March 2011 and March 2017 at the University Hospital Salzburg were enrolled. Knee function was assessed postoperatively using two validated orthopaedic scores: Tegner Lysholm Knee Scoring Scale (TL) and Knee Society Score (KSS); both range from 0 to 100 (100 being no impairment). Scars were evaluated using the Patient and Observer Scar Assessment Scale (POSAS) (range 6-60). Thirty-eight patients were enrolled. The average postoperative TL score was 95.68 (range 66-100). The mean KSS clinical examination and function scores were 96.8 (range 58-100) and 97.11 (range 60-100), respectively. Flap type (osteocutaneous vs. non-osteocutaneous) did not correlate with TL or KSS scores. KSS and TL scores showed no association with vascular pedicle length or transplant volume. The average POSAS patient and observer scores were 6.84 and 15.24, respectively. POSAS observer scores were significantly higher for osteocutaneous flaps than for non-osteocutaneous flaps. The MFC flap causes minimal donor site morbidity. No knee joint instability or range of motion limitation was found. Postoperative TL and KSS scores indicated excellent knee function.

Superconductivity of metallic aluminum antimonide.

The high-pressure metallic phase of aluminunm antimnonide is super conducting [critical temperature T(c) (P approximately 125 kilobars) = 2.8 degrees +/-0.2 degrees K]. This transition temperature is significantly lower than the transition temperature of metallic germanium under an equivalent high pressure. A similar result had been previously found for superconducting indiumantimonide in comparison to tin.

Superconducting phosphorus.

Phosphorus, the element itself, becomes superconducting near 4.7 degrees K and at pressures exceeding 100 kilobars. This constitutes one of the four last missing links in the proof that superconductivity is normal behavior for every truly metallic sp element. The three remaining ones are arsenic, sulfur, and iodine.

Atypical echocardiographic and angiographic presentation of a postoperative pseudoaneurysm of the left ventricle after repair of a true aneurysm.

Subsequent to the repair of a true aneurysm from the posteromedial-basal aspect of the left ventricle, a 58 year old man developed a draining wound at the site of the sternotomy. Two-dimensional echocardiography revealed recurrence of the aneurysm at the site of the previous aneurysm repair. This aneurysm had a wide neck and looked similar in appearance to the previous true aneurysm. However, at surgery the patient was found to have a ventricular pseudoaneurysm with a cardiocutaneous fistula.

The effect on atrial and ventricular intracellular potentials, and other pharmacological actions of L9146, a non-halogenated benzo(b)thiophene related to amiodarone.

L9146 was synthesised in the hope of eliminating the unwanted side-effects of amiodarone which has been shown to be effective in the control of atrial fibrillation, flutter, and in pre-excitation syndromes such as Wolff-Parkinson-White syndrome. L9146 has pharmacological and electrophysiological effects similar to those of amiodarone. It is an antagonist of both alpha and beta adrenoceptor-mediated cardiovascular effects of a noncompetitive type. It lowers vascular resistance briefly, and causes a longer lasting bradycardia. It moderately reduces the maximum rate of depolarisation (MRD), conduction velocity, and totally suppresses ventricular pacemakers activated by high doses of isoprenaline. In addition, L9146 greatly prolongs action potential duration (APD) in atrial and ventricular muscle. In normal ventricular conducting tissue the action potential duration (APD) is shorter in the bundle of His than in the false tendons, and shorter still in the ventricular muscle. L9146 lengthened APD throughout, but particularly in the proximal portion, and even more in the muscle, so that APD became uniform. The decrement of conduction of premature action potentials was increased to the point at which slowly conducting premature AP's were eliminated altogether.

Echocardiographic observations of calcium in operatively excised stenotic aortic valves.

Qualitative and quantitative 2-dimensional (2-D) echocardiographic methods were developed to define the anatomic and physiologic significance of valvular calcium in aortic stenosis (AS). Qualitative methods assigned etiologic diagnoses by matching patterns of calcium with anatomic criteria. Quantitative techniques measured echodensities from superimposed short-axis views of calcium. Fifty-five pathologic specimens procured from surgery were photographed and radiographed. Etiologic diagnoses were assigned from gross examination and radiodensities were planimetered. Echocardiographic and anatomic diagnoses were compared. Sensitivities for diagnosing the most common etiologies, congenitally bicuspid and degenerative, were 58% and 100% and specificities were 100% and 76%. Calcium tended to be heaviest in congenitally diseased valves and lightest in those with degenerative disease (p less than 0.2) and showed propensity for the right cusp in all etiologies except for those with degenerative disease. Correlation of echodensities to radiodensities was 0.82. The relation of calcific echodensities to orifice area was curvilinear; beyond a level of calcium, further deposits did not reduce the orifice more. A systematic echocardiographic examination of calcium in stenotic aortic valves can give a correct etiologic diagnosis in most patients and identify the severely narrowed orifice.

Investigations to characterize a new anti-arrhythmic drug, ORG 6001 including a simple test for calcium antagonism.

1 The compound Org 6001 (3alpha-amino-2beta-hydroxy-5alpha-androstan-17-one hydrochloride) was found in recent experiments to exhibit anti-arrhythmic activity. Evidence is presented in this paper concerning its mode of action. 2 Org 6001 was 1.8 times more potent than procaine as a local anaesthetic on desheathed frog nerve. 3 Org 6001 had no effect on the resting potential of isolated cardiac muscle of rabbit, but greatly reduced the maximum rate of depolarization tion (MRD). The action potential duration TAPD) WAS MARGINALLY PROLONGED IN ATRIAL AND VENTRICULAR MUSCLE. 4 Org 6001 preferentially shortened APD in that part of the Purkinje system in which APD is normally longer than elsewhere, so that APD

Intraoperative mapping of atrial activation before, during, and after the Mustard operation.

Thirty-eight patients with transposition of the great arteries underwent intraoperative mapping of atrial epicardium and endocardium during various stages of the operative procedure. The purpose was to determine the electrophysiological basis of the postoperative supraventricular arrhythmias associated with this operation. Comparisons were made between atrial activation patterns and times before and after each of the following stages: (1) cannulation, (2) atriotomy, (3) excision of atrial septum and coronary sinus, and (4) placement of intra-atrial baffle. The first stage produced no significant changes in atrial activation times or patterns but did demonstrate a shift of the functional pacemaker to the sulcus terminalis in 8 of 14 patients studied. Longitudinal atriotomy did not significantly lengthen atrial activation. Transverse atriotomy did not alter activation times of the His bundle but did significantly change patterns of epicardial and endocardial activation. Excision of the septum and coronary sinus always produced block in the posterior crista terminalis, and placement of a baffle worsened this block. Four patients developed nodal rhythm on the operating table and had both a posterior crista terminalis block and anterior septal block. Suggestions for modification in the surgical techniques were advanced to help prevent rhythm disturbances in paitients undergoing transvenous correction of transposition of the great arteries.

Early valve replacement in active infective endocarditis. Results and late survival.

In the past 14 years, 42 patients with active infective endocarditis underwent early valve replacement for severe congestive heart failure, major prosthetic dehiscence, intramyocardial abscesses, sepsis, or major embolization. Blood cultures were positive in 40 patients and the valve tissues were positive in two others. All patients received antimicrobials for from 1 to 4 weeks. Drug addiction was noted in 24%, urinary tract manipulation in 7%, dental work in 5%, contaminated prosthesis in 2%, and unknown cause in 62%. Organisms were predominantly staphylococcal (43%) and streptococcal (41%); the remainder were gram-negative (9%) or fungal (7%). The aortic valve was involved in 72%, mitral in 14%, tricuspid in 7%, and both aortic and mitral in 7%. By the New York Heart Association (NYHA) functional classification, 90% (38/42) were in Class III or IV. Operative mortality was 10% (4/42) and all four patients had preexisting renal failure necessitating dialysis. No predominant organism correlated with early deaths. In aortic valve replacement (30 patients), operative mortality was 7%. Postoperatively, 95% (35/37) were Class I or II with one lost to follow-up. Subsequent reoperation was required in five patients (13%) for recurrent endocarditis, with an operative mortality of 20% (1/5). Late death occurred in 45% (17/38). Overall probability of survival was 0.53 at 5 years. For isolated aortic valve involvement, the 5 year survival was 0.58. Survival for native valve involvement was 0.58 and for prosthetic endocarditis, 0.55. This study shows that after at least 1 week of antibiotics, early operation in patients with active endocarditis has an acceptable operative mortality. Clinical improvement is excellent in 95% and more than half survived 5 years or longer.

Hemodynamic effect of myocardial revascularization in the impaired ventricle.

The hemodynamic effect of myocardial revascularization with saphenous vein grafts (mean 3.3 per patient) was analyzed 1 year after operation in 111 patients. Operations were performed using one continuous period of aortic cross-clamping with hyperkalemic cardioplegia for distal anastomoses in 84% of patients; 16% had arrest with topical and systemic hypothermia for myocardial protection. Group I (N = 18) had normal ventricles (ejection fraction [EF] greater than 50%; left ventricular end-diastolic pressure [LVEDP] less than or equal to 12 torr); Group II (N = 64) had ischemic ventricles (EF greater than 50%, LVEDP greater than 13 torr); and Group III (N = 30) had abnormal ventricles (EF less than 50%, LVEDP greater than 13 torr). Hemodynamic measurements were obtained before and 1 year after operation. Fifteen of 18 patients (83%) in Group I did not show significant hemodynamic changes, but in three EF decreased by greater than or equal to 10% and LVEDP increased by greater than 10% over preoperative levels. In Group II, EF was unchanged or slightly better in 89% (57/64) and worse in seven patients. Improvement in cardiac index (p less than 0.01) and LVEDP (p less than 0.001) was significant. Worsening of EF in 10 of 82 patients in Groups I and II was attributed to graft closure and/or poor myocardial protection. In Group III, significant improvement in cardiac index (p less than 0.001), EF (p less than 0.001), and LVEDP (p less than 0.01) was also noted. A subset of nine patients with EF less than or equal to 35% showed postoperative improvement in 56%. Of the remaining 20 patients with an EF of greater than 35% to less than 50%, half had greater than or equal to 20% improvement in postoperative EF. Operative mortality was 3.3% (1/30) for Group III. Late mortality was 1.5% (1/64) for Group II and 10% (3/29) for Group III. Significant improvement was noted postoperatively in 67% (57/85) of all patients who had preoperative treadmill tests (p less than 0.001). This study shows that myocardial revascularization significantly improved left ventricular performance in most patients with ischemic and abnormal ventricles. Previous studies that fail to show improvement may be related to incomplete revascularization and/or poor myocardial preservation. These data, therefore, justify the need for revascularization of the impaired ventricle.

Pharmacokinetics and bioavailability of quercetin glycosides in humans.

Due to its potentially beneficial impact on human health, the polyphenol quercetin has come into the focus of medicinal interest. However, data on the bioavailability of quercetin after oral intake are scarce and contradictory. Previous investigations indicate that the disposition of quercetin may depend on the sugar moiety of the glycoside or the plant matrix. To determine the influence of the sugar moiety or matrix on the absorption of quercetin, two isolated quercetin glycosides and two plant extracts were administered to 12 healthy volunteers in a four-way crossover study. Each subject received an onion supplement or quercetin-4'-O-glucoside (both equivalent to 100 mg quercetin), as well as quercetin-3-O-rutinoside and buckwheat tea (both equivalent to 200 mg quercetin). Samples were analyzed by HPLC with a 12-channel coulometric array detector. In human plasma, only quercetin glucuronides, but no free quercetin, could be detected. There was no significant difference in the bioavailability and pharmacokinetic parameters between the onion supplement and quercetin-4'-O-glucoside. Peak plasma concentrations were 2.3 +/- 1.5 microg x mL(-1) and 2.1 +/- 1.6 microg x mL(-1) (mean +/- SD) and were reached after 0.7 +/- 0.2 hours and 0.7 +/- 0.3 hours, respectively. After administration of buckwheat tea and rutin, however, peak plasma levels were--despite the higher dose-only 0.6 +/- 0.7 microg x mL(-1) and 0.3 +/- 0.3 microg x mL(-1), respectively. Peak concentrations were reached 4.3 +/- 1.8 hours after administration of buckwheat tea and 7.0 +/- 2.9 hours after ingestion of rutin. The terminal elimination half-life was about 11 hours for all treatments. Thus, the disposition of quercetin in humans primarily depends on the sugar moiety. To a minor extent, the plant matrix influences both the rate and extent of absorption in the case of buckwheat tea administration compared with the isolated compound. The site of absorption seems to be different for quercetin-4'-O-glucoside and quercetin-3-O-rutinoside. The significance of specific carriers on the absorption of quercetin glycosides, as well as specific intestinal beta-glucosidases, needs to be further evaluated.

Coronary artery bypass in hereditary factor XI deficiency.

Hereditary factor XI deficiency is a disorder of coagulation that has been associated with postoperative bleeding. Because cardiopulmonary bypass itself induces transient abnormalities in hemostasis, the patient with factor XI deficiency could be at increased risk for bleeding after cardiac surgical procedures. We report the successful management of a 61-year-old man with hereditary factor XI deficiency who had coronary artery bypass. Treatment with low-dose aspirin, begun 24 hours postoperatively for graft patency, was well tolerated. Once recognized and aggressively treated, factor XI deficiency does not appear to be a contraindication to potentially life-saving procedures like coronary revascularization.

Surgical treatment of ventricular arrhythmias using epicardial, transmural, and endocardial mapping.

In 3 patients with ischemic coronary disease or primary myocardiopathy who were unresponsive to conventional and experimental antiarrhythmia therapy, surgical treatment of intractable ventricular tachycardia was performed using epicardial, transmural, and endocardial mapping techniques. An experimental canine model of acute and chronic myocardial ischemia with recurrent ventricular tachycardia was developed to refine the mapping technique for clinical use. In patients and animals alike, atrial overdrive pause pacing, premature ventricular pacing, or both were used to bring outa repeatable pattern of tachycardia. Mapping techniques distinguished the irritable focus so that surgical excision of the site of earliest activation could be performed. In addition, the mapping techniques were used in the validation following excision. The limitations of epicardial mapping alone in locating all areas of premature focus are discussed, and the need for mapping in ventricular aneurysm is demonstrated.

Jaundice associated with polycystic liver disease.

Jaundice is rarely encountered in polycystic disease of the liver. In the present case, pressure from tense cysts at the hilus of the liver caused a marked narrowing of the common hepatic duct and slowing of bile flow with the formation of stasis stones. Decompression of the cysts and removal of debris in the intrahepatic ducts resulted in a rapid decrease of the serum bilirubin level.