NiTiHf-based shape memory alloys

Abstract

NiTiHf-based shape memory alloys have been receiving considerable attention for high temperature, high strength and two-way shape memory applications since they could have transformation temperatures above 100°C, shape memory effect under high stress (above 500 MPa) and superelasticity above 100°C. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf-based alloys have some drawbacks such as low ductility and high slope in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing. It has been revealed that microstructural control is crucial to govern the shape memory properties (e.g. transformation temperatures, matrix strength, shape recovery strain, twinning type, etc.) of NiTiHf-based alloys. A summary of the most recent improvements on selected NiTiHf-based systems is presented to point out their significant shape memory properties, effects of alloying, aging and microstructure of transforming phases and precipitates.     

High-Rate Diamond Deposition by Combustion Flame Method Using Twin Acetylene/Oxygen Gas Welding Torch

To develop a high-rate diamond deposition process using combustion flame method, diamond deposition equipment with twin acetylene/oxygen welding torch was manufactured, and diamond deposition by using this equipment was carried out. 304 Stainless steel plates and molybdenum plates were used as substrates. The diamond deposition was conducted under the following conditions: oxygen flow rate: 1.25 SLM, acetylene/oxygen flow ratio: 1.15, and diamond deposition temperature: around 1473 K. Consequently, diamonds could be deposited even on the stainless steel substrate, and diamond deposition rate was promoted by using twin torch equipment. Besides, the diamond/molybdenum hybrid coating using diamonds deposited by twin torch equipment have the same wear-resistant property as that using diamonds by the single torch equipment. From these results, this technique was thought to have high potential for high-rate diamond deposition in combustion flame method.     

Quantitating dialysis using two dialysate samples: a simple, practical and accurate approach for evaluating urea kinetics

AIM: Factors which influence the accuracy of the field application during daily irradiation routine are not well known. The aim of this prospective analysis was to determine the significance of these factors on the occurrence of field misadjustments in irradiation without immobilization and to evaluate their clinical relevance. PATIENTS AND METHODS: Fifty-three patients received external cobalt-60 beam irradiation without fixation. Once weekly portal images of all treatment fields were carried out. In addition to objective patient data (age, weight, height, general condition, irradiation indication), the psychological situation of the patient during treatment (anxiety, restlessness, pain) and work circumstances of the medical staff during treatment were evaluated once weekly. The distance of clearly visible anatomic structures to the field borders of the portal images were measured and the deviation to the corresponding simulator images was calculated. Patient data were correlated to the number of field misadjustments (deviation larger than 1 cm). RESULTS: Patients whose condition is generally poor and patients being treated palliatively, patients with feeling of anxiety, restlessness or pain during simulation or irradiation and heavy patients (90 kg and more) were more often misadjusted. The number of field misadjustments increased with the stress of the medical staff. CONCLUSIONS: The problem of reproducibility of external beam irradiation without fixation in palliative treatment is of clinical relevance. Effective analgesic therapy and a comfortable and painfree patient set-up reduce misadjustments. In curative treatment, immobilization techniques should be used.     

Quantitating Dialysis in the Home Hemodialysis Patient: A Simple and Practical Approach

Home hemodialysis is the most cost-effective form of dialysis and is associated with the lowest mortality. Home hemodialysis patients are usually highly motivated, independent, and actively employed. Because of the minimal supervision they require and the fact that they are not in a controlled environment, it is easy to overlook the measurement of their dialysis adequacy. We studied 6 home hemodialysis patients and demonstrated that blood urea measured 30 min before the end of dialysis (Ct-30) is equivalent to that measured 30 min after the end of dialysis (Ct+30). The Kt/V results using Ct-30, Kt/V(Ct-30), were almost equivalent to Kt/V(Ct+30) (p = 0.5). The Kt/V Kt/V(Ct) using blood urea measured at the end of dialysis (Ct) significantly overestimated Kt/V(Ct-30) and Kt/V(Ct+30) (p = 0.007) The calculated percent reduction of urea (PRU) was about 5% less when using Ct-30 compared with Ct (p = 0.001). Taking blood samples 30 min before the end of dialysis for urea kinetics is more convenient for the home dialysis patients, since no other technical aspects of dialysis need their attention. The samples can be delivered to the laboratory the following day, because the blood may be stored in heparinized tubes at 4°C without deterioration of urea and creatinine concentrations. The Kt/V(Ct-30) was almost equal to Kt/V(Ct+30), so there is no longer any concern for the errors introduced by urea rebound. The blood pump must be reduced to 80 mL/min for about 10 sec to eliminate the errors due to fistula and cardiopulmonary recirculation. A simple programmable calculator will facilitate the calculation of accurate results using the Daugirdas second-generation formula.     

Callatostatins: neuropeptides from the blowfly Calliphora vomitoria with sequence homology to cockroach allatostatins

Five neuropeptides with C-terminal amino acid sequence homology to cockroach allatostatins have been identified in the blowfly Calliphora vomitoria. Three have the same pentapeptide C-terminal amino acid sequence as allatostatin 1 of the cockroach Diploptera punctata. A hexadecapeptide designated callatostatin 1, isolated from thoracic ganglia, brains, and heads, has the sequence Asp-Pro-Leu-Asn-Glu-Glu-Arg-Arg-Ala-Asn-Arg-Tyr-Gly-Phe-Gly-Leu-NH2. Callatostatins 2 and 3 have been isolated from heads and thoracic ganglia, respectively; they comprise the last 14 and 8 residues of callatostatin 1. Callatostatin 4, isolated from thoracic ganglia, has the sequence Xaa-Arg-Pro-Tyr-Ser-Phe-Gly-Leu-NH2, where Xaa is either Asp or Asn. This peptide, with a serine substitution for glycine at position 5, has a C-terminal pentapeptide sequence identical to that of allatostatins 3 and 4 of D. punctata. Callatostatin 5, with the sequence Gly-Pro-Pro-Tyr-Asp-Phe-Gly-Met-NH2, was identified from whole flies. All five peptides inhibit juvenile hormone production by the corpora allata of D. punctata in vitro. Callatostatin 5 was the most potent allatostatin so far tested in this species, with maximum inhibition occurring at 1 nM. In contrast, none of the callatostatins or the allatostatins showed allatostatic activity in mature female C. vomitoria when tested at concentrations of 100 to 0.1 microM. In accordance with these results, immunoreactivity to an antiserum directed against the common C terminus of callatostatin 1 and allatostatin 1 was observed in the corpora allata of D. punctata but not in the corpus allatum of C. vomitoria, despite its presence in neurons of the brain. Neurons in the thoracic ganglion of C. vomitoria that are immunoreactive against this antiserum project to the hindgut, rectum, rectal papillae, and oviduct, suggestive of a function different from that of a true allatostatin.     

Refractory ascites in cirrhosis: roles of volume expansion and plasma atrial natriuretic factor level elevation

Cirrhotic patients with ascites refractory to diuretics also have blunted response to marked elevations of plasma atrial natriuretic factor levels alone or to moderate intravascular volume expansion by head-out water immersion. However, these patients usually undergo natriuresis after peritoneovenous shunting. To dissect the factors responsible for this response, we studied the effects on separate days of moderate intravascular volume expansion and highly elevated plasma atrial natriuretic factor levels (head-out water immersion and atrial natriuretic factor infusion) or marked volume expansion and moderate plasma atrial natriuretic factor level elevation (head-out water immersion and albumin infusion) in 13 alcoholic cirrhotic patients with massive ascites. Three of these patients, who responded to initial head-out water immersion with a negative sodium balance, served as controls. Unresponsiveness to head-out water immersion was confirmed in the remaining 10 patients on both days on the basis of blunted natriuretic response (urinary sodium excretion < 0.8 mmol/hr after 2 hr). In contrast, these 10 refractory patients were able to achieve negative sodium balance with both combinations. Mean urinary sodium excretion increased from a baseline level of 0.13 +/- 0.10 mmol/hr to a peak level of 2.29 +/- 0.61 mmol/hr after head-out water immersion and atrial natriuretic factor infusion and from 0.10 +/- 0.3 mmol/hr to 1.61 +/- 0.62 mmol/hr after head-out water immersion and albumin infusion. Both maneuvers were associated with suppression of plasma renin activity and serum aldosterone levels. With head-out water immersion and atrial natriuretic factor infusion, we noted a significant increase in 5' cyclic GMP levels, a second messenger of atrial natriuretic factor, indicating possible activation of atrial natriuretic factor receptors at the inner medullary collecting ducts. In contrast, with head-out water immersion and albumin infusion no such increase in levels occurred, indicating that the increase in urinary sodium excretion was mainly due to increased delivery of sodium to the cortical distal nephron, as indicated by a disproportionate increase in urinary potassium excretion. In conclusion, massive (as opposed to moderate) volume expansion or greatly elevated levels of plasma atrial natriuretic factor associated with moderate volume expansion can improve blunted atrial natriuretic factor responsiveness in cirrhotic patients with refractory ascites. This appears to be achieved by way of a marked increase in distal delivery of filtrate in the kidney, with or without activation of distal atrial natriuretic factor receptors in the inner medullary collecting ducts.     

Measurement of emotional reactivity and association ability of the Tsukuba emotional strains of rats (Rattus norvegicus) in licking and lever-pressing conditioned suppression situations.

The emotional reactivity and association ability of the Tsukuba High Emotional (THE), the Tsukuba Low Emotional (TLE), and the Wistar-Imamichi (WI) strains of rats were studied in two experiments. Suppression of licking and lever pressing by unsignaled shocks were used to measure emotionality in Experiments 1 and 2, respectively. Contrary to our expectations, the WI rats which had formed a part of the foundation population of the Tsukuba strains, proved to be the most emotional, and the THE and TLE did not differ in emotionality from each other in either experiment. Association ability was measured by the speed of discriminating dangerous and safe periods under matched levels of emotional arousal. Association ability proved to be best in TLE rats, especially in Experiment 2, in which the procedures were somewhat improved on the basis of the results of Experiment 1. We discuss the results in terms of the motivational system and of the behavioral characteristics established during the course of selective breeding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Marker-fusion PCR for one-step mutagenesis of essential genes in yeast.

We describe a one-step gene replacement method based on fusion PCR that can be used to mutagenize essential genes at their endogenous locus. Marker-fusion PCR can facilitate transfer of alleles between strains as well as PCR-based techniques, such as site-directed and error-prone PCR mutagenesis, all without cloning or strain constructions. With this method, PCR is used to fuse a mutagenized fragment to an overlapping fragment containing a selectable marker flanked by regions of homology to the target. By transforming yeast with these PCR products, specific mutations are introduced at the endogenous locus through homologous recombination. We tested the 'marker-fusion PCR' method using the budding yeast CDC28 gene and were able to efficiently introduce site-directed mutations and integrate genomic or plasmid-borne mutant alleles. As a further application for this method, we used a spiked oligonucleotide to randomize the coding sequence for a single domain of CDC28 and were able to construct highly mutagenized libraries for this region.