Thermoelectric performance of p-type TiCoSb half-Heusler compounds - Intrinsic phase separation and charge carrier concentration optimization as key to high efficiency

The world's rising demand of energy turns the development of sustainable and more efficient technologies for energy production and storage into an inevitable task. Thermoelectric generators, composed of pairs of n-type and p-type semiconducting materials, di¬rectly transform waste heat into useful electricity. The efficiency of a thermoelectric mate¬rial depends on its electronic and lattice properties, summarized in its figure of merit ZT. Desirable are high electrical conductivity and Seebeck coefficients, and low thermal con¬ductivity. Half-Heusler materials are very promising candidates for thermoelectric applications in the medium¬ temperature range such as in industrial and automotive waste heat recovery. The advantage of Heusler compounds are excellent electronic properties and high thermal and mechanical stability, as well as their low toxicity and elemental abundance. Thus, the main obstacle to further enhance their thermoelectric performance is their relatively high thermal conductivity.rn rnIn this work, the thermoelectric properties of the p-type material (Ti/Zr/Hf)CoSb1-xSnx were optimized in a multistep process. The concept of an intrinsic phase separation has recently become a focus of research in the compatible n-type (Ti/Zr/Hf)NiSn system to achieve low thermal conductivities and boost the TE performance. This concept is successfully transferred to the TiCoSb system. The phase separation approach can form a significant alternative to the previous nanostructuring approach via ball milling and hot pressing, saving pro¬cessing time, energy consumption and increasing the thermoelectric efficiency. A fundamental concept to tune the performance of thermoelectric materials is charge carrier concentration optimization. The optimum carrier concentration is reached with a substitution level for Sn of x = 0.15, enhancing the ZT about 40% compared to previous state-of-the-art samples with x = 0.2. The TE performance can be enhanced further by a fine-tuning of the Ti-to-Hf ratio. A correlation of the microstructure and the thermoelectric properties is observed and a record figure of merit ZT = 1.2 at 710°C was reached with the composition Ti0.25Hf0.75CoSb0.85Sn0.15.rnTowards application, the long term stability of the material under actual conditions of operation are an important issue. The impact of such a heat treatment on the structural and thermoelectric properties is investigated. Particularly, the best and most reliable performance is achieved in Ti0.5Hf0.5CoSb0.85Sn0.15, which reached a maximum ZT of 1.1 at 700°C. The intrinsic phase separation and resulting microstructure is stable even after 500 heating and cooling cycles.

Numerical evaluation of material model and thickness effect on LSP induced residual stresses

Laser Shock Peening (LSP) is a technological process used to improve mechanical properties in metallic components. When a short and intense laser pulse irradiates a metallic surface, high pressure plasma is generated on the treated surface; elasto-plastic waves, then, propagate inside the target and create plastic strain. This surface treatment induces a deep compressive residual stresses field on the treated area and through the thickness; such compressive residual stress is expected to increase the fatigue resistance, and reduce the detrimental effects of corrosion and stress corrosion cracking.

Galactic fountain flows in high-resolution hydrodynamical simulations of galaxy disks

Feedback from the most massive components of a young stellar cluster deeply affects the surrounding ISM driving an expanding over-pressured hot gas cavity in it. In spiral galaxies these structures may have sufficient energy to break the disk and eject large amount of material into the halo. The cycling of this gas, which eventually will fall back onto the disk, is known as galactic fountains. We aim at better understanding the dynamics of such fountain flow in a Galactic context, frame the problem in a more dynamic environment possibly learning about its connection and regulation to the local driving mechanism and understand its role as a metal diffusion channel. The interaction of the fountain with a hot corona is hereby analyzed, trying to understand the properties and evolution of the extraplanar material. We perform high resolution hydrodynamical simulations with the moving-mesh code AREPO to model the multi-phase ISM of a Milky Way type galaxy. A non-equilibrium chemical network is included to self consistently follow the evolution of the main coolants of the ISM. Spiral arm perturbations in the potential are considered so that large molecular gas structures are able to dynamically form here, self shielded from the interstellar radiation field. We model the effect of SN feedback from a new-born stellar cluster inside such a giant molecular cloud, as the driving force of the fountain. Passive Lagrangian tracer particles are used in conjunction to the SN energy deposition to model and study diffusion of freshly synthesized metals. We find that both interactions with hot coronal gas and local ISM properties and motions are equally important in shaping the fountain. We notice a bimodal morphology where most of the ejected gas is in a cold $10^4$ K clumpy state while the majority of the affected volume is occupied by a hot diffuse medium. While only about 20\% of the produced metals stay local, most of them quickly diffuse through this hot regime to great scales.

Fire victim identification by post-mortem dental CT: Radiologic evaluation of restorative materials after exposure to high temperatures

The aim of this study was to evaluate the use of high resolution CT to radiologically define teeth filling material properties in terms of Hounsfield units after high temperature exposure.

Eosinophilic vasculitis: an inhabitual and resistant manifestation of a vasculitis

A 55-year-old woman was referred because of diffuse pruritic erythematous lesions and an ischemic process of the third finger of her right hand. She was known to have anaemia secondary to hypermenorrhea. She presented six months before admission with a cutaneous infiltration on the left cubital cavity after a paravenous leakage of intravenous iron substitution. She then reported a progressive pruritic erythematous swelling of her left arm and lower extremities and trunk. Skin biopsy of a lesion on the right leg revealed a fibrillar, small-vessel vasculitis containing many eosinophils.Two months later she reported Raynaud symptoms in both hands, with a persistent violaceous coloration of the skin and cold sensation of her third digit of the right hand. A round 1.5 cm well-delimited swelling on the medial site of the left elbow was noted. The third digit of her right hand was cold and of violet colour. Eosinophilia (19 % of total leucocytes) was present. Doppler-duplex arterial examination of the upper extremities showed an occlusion of the cubital artery down to the palmar arcade on the right arm. Selective angiography of the right subclavian and brachial arteries showed diffuse alteration of the blood flow in the cubital artery and hand, with fine collateral circulation in the carpal region. Neither secondary causes of hypereosinophilia nor a myeloproliferative process was found. Considering the skin biopsy results and having excluded other causes of eosinophilia, we assumed the diagnosis of an eosinophilic vasculitis. Treatment with tacrolimus and high dose steroids was started, the latter tapered within 12 months and then stopped, but a dramatic flare-up of the vasculitis with Raynaud phenomenon occurred. A new immunosuppressive approach with steroids and methotrexate was then introduced. This case of aggressive eosinophilic vasculitis is difficult to classify into the usual forms of vasculitis and constitutes a therapeutic challenge given the resistance to current immunosuppressive regimens.

Anisotropy in plastic deformation of extruded magnesium alloy sheet during tensile straining at high temperature

Experimental measurements are used to characterize the anisotropy of flow stress in extruded magnesium alloy AZ31 sheet during uniaxial tension tests at temperatures between 350°C and 450°C, and strain rates ranging from 10-5 to 10-2 s-1. The sheet exhibits lower flow stress and higher tensile ductility when loaded with the tensile axis perpendicular to the extrusion direction compared to when it is loaded parallel to the extrusion direction. This anisotropy is found to be grain size, strain rate, and temperature dependent, but is only weakly dependent on texture. A microstructure based model (D. E. Cipoletti, A. F. Bower, P. E. Krajewski, Scr. Mater., 64 (2011) 931–934) is used to explain the origin of the anisotropic behavior. In contrast to room temperature behavior, where anisotropy is principally a consequence of the low resistance to slip on the basal slip system, elevated temperature anisotropy is found to be caused by the grain structure of extruded sheet. The grains are elongated parallel to the extrusion direction, leading to a lower effective grain size perpendicular to the extrusion direction. As a result, grain boundary sliding occurs more readily if the material is loaded perpendicular to the extrusion direction.

Polymorphisms in the ABCB1 gene in phenobarbital responsive and resistant idiopathic epileptic Border Collies

BACKGROUND: Variation in the ABCB1 gene is believed to play a role in drug resistance in epilepsy. HYPOTHESIS/OBJECTIVES: Variation in the ABCB1 gene encoding the permeability-glycoprotein could have an influence on phenobarbital (PB) resistance, which occurs with high frequency in idiopathic epileptic Border Collies (BCs). Animals: Two hundred and thirty-six client-owned BCs from Switzerland and Germany including 25 with idiopathic epilepsy, of which 13 were resistant to PB treatment. METHODS: Prospective and retrospective case-control study. Data were collected retrospectively regarding disease status, antiepileptic drug (AED) therapy, and drug responsiveness. The frequency of a known mutation in the ABCB1 gene (4 base-pair deletion in the ABCB1 gene [c.296_299del]) was determined in all BCs. Additionally, the ABCB1 coding exons and flanking sequences were completely sequenced to search for additional variation in 41 BCs. Association analyses were performed in 2 case-control studies: idiopathic epileptic and control BCs and PB-responsive and resistant idiopathic epileptic BCs. RESULTS: One of 236 BCs (0.4%) was heterozygous for the mutation in the ABCB1 gene (c.296_299del). A total of 23 variations were identified in the ABCB1 gene: 4 in exons and 19 in introns. The G-allele of the c.-6-180T > G variation in intron 1 was significantly more frequent in epileptic BCs resistant to PB treatment than in epileptic BCs responsive to PB treatment (P(raw) = .0025). CONCLUSIONS AND CLINICAL IMPORTANCE: A variation in intron 1 of the ABCB1 gene is associated with drug responsiveness in BCs. This might indicate that regulatory mutations affecting the expression level of ABCB1 could exist, which may influence the reaction of a dog to AEDs.

Therapy of steroid-resistant inflammatory bowel disease

Although systemic corticosteroids are successfully administered for the induction of clinical response and remission in the majority of patients with inflammatory bowel disease (IBD) presenting with a flare, a proportion of these patients demonstrate a primary nonresponse to steroids or in the case of an initial response, they develop a resistance or a steroid dependence. Long-term therapy with corticosteroids for treatment of IBD should be avoided, given the high frequency of adverse treatment effects. Knowledge about treatment strategies in case of steroid nonresponse is therefore highly relevant.

Safe high-pressure freezing of infectious micro-organisms

We describe how high-pressure freezing of infectious biological material can safely be accomplished with the help of membrane carriers. The method described is easy to perform; however, careful manipulations are required. Existing safety regulations must still be followed. However, the procedure reduces the risk of dissemination of infectious material.

Vertical transmission of a fluoroquinolone-resistant Escherichia coli within an integrated broiler operation

The epidemiology of an enrofloxacin-resistant Escherichia coli clone was investigated during two separate outbreaks of colibacillosis in the Danish broiler production. In total five flocks were reported affected by the outbreaks. Recorded first-week mortalities were in the range of 1.7-12.7%. The clone was first isolated from dead broilers and subsequently demonstrated in samples from associated hatchers and the parent flock with its embryonated eggs, suggesting a vertical transmission from the parents. The second outbreak involved two broiler flocks unrelated to the affected flocks from the first outbreak. However, the clone could not be demonstrated in the associated parent flock. Furthermore, samplings from grand-parent flocks were negative for the outbreak clone. The clonality was evaluated by plasmid profiling and pulsed-field gel electrophoresis. None of the recognized virulence factors were demonstrated in the outbreak clone by microarray and PCR assay. The molecular background for the fluoroquinolone-resistance was investigated and point mutations in gyrA and parC leading to amino-acid substitutions in quinolone-resistance determining regions of GyrA and ParC were demonstrated. Vertical transmission of enrofloxacin-resistant E. coli from healthy parents resulting in high first-week mortality in the offspring illustrates the potential of the emergence and spreading of fluoroquinolone-resistant bacteria in animal husbandry, even though the use of fluoroquinolones is restricted.

Aortic rupture in high-speed skiing crashes

BACKGROUND: New equipment and techniques in winter sports, such as carving skis and snowboards, have brought up new trauma patterns into the spectrum of leisure trauma. The injuries resemble high-energy trauma known from road crashes. The aim of the present study was to assess the incidence of acute traumatic descending aortic rupture in recreational skiing-crashes. MATERIAL: Between January 1995 and December 2004, 22 patients were admitted to our hospital for aortic rupture. Four patients had skiing crashes (18.2%). Mean age was 31 years, all patients were male. In two cases, aortic rupture was associated with fractures of the upper and lower extremities. One patient additionally had a cerebral contusion with an initial Glasgow Coma Scale score of 13. In two patients, isolated aortic rupture was diagnosed. RESULTS: Two patients were treated by graft interposition, and one by endograft. One patient arrived under mechanical resuscitation without blood pressure. He died at admission. He had been observed for 5 hours in another hospital, complaining of severe intrascapular back pain, before transport to our trauma unit for unknown bleeding. In the other three cases, treatment was successful. CONCLUSION: Rescue services and paramedics should be aware of this new type of injury. Acute aortic rupture has to be considered as possible injury in high velocity skiing crashes.

Diversity of Mycoplasma hyopneumoniae in pig farms revealed by direct molecular typing of clinical material

Mycoplasma hyopneumoniae is the etiological agent of enzootic pneumonia in swine. Various reports indicate that different strains are circulating in the swine population. We investigated the variety of M. hyopneumoniae strains by a newly developed genetic typing method based on the polyserine repeat motif of the LppS homolog P146. PCR amplification using M. hyopneumoniae specific, conserved primers flanking the region encoding the repeat motif, followed by sequencing and cluster analysis was carried out. The study included strains isolated from different geographic regions as well as lysates from lung swabs from a series of pig farms in Switzerland. High diversity of M. hyopneumoniae was observed but farms being in close geographic or operative contact generally seemed to be affected by the same strains. Moreover, analysis of multiple samples from single pig farms indicated that these harbored the same, farm-specific strain. The results indicate that multiple strains of M. hyopneumoniae are found in the swine population but that specific strains or clones are responsible for local outbreaks. The method presented is a highly reproducible epidemiologic tool allowing direct typing of M. hyopneumoniae from clinical material without prior isolation and cultivation of strains.

Patent foramen ovale and high-altitude pulmonary edema

CONTEXT: Individuals susceptible to high-altitude pulmonary edema (HAPE) are characterized by exaggerated pulmonary hypertension and arterial hypoxemia at high altitude, but the underlying mechanism is incompletely understood. Anecdotal evidence suggests that shunting across a patent foramen ovale (PFO) may exacerbate hypoxemia in HAPE. OBJECTIVE: We hypothesized that PFO is more frequent in HAPE-susceptible individuals and may contribute to more severe arterial hypoxemia at high altitude. DESIGN, SETTING, AND PARTICIPANTS: Case-control study of 16 HAPE-susceptible participants and 19 mountaineers resistant to this condition (repeated climbing to peaks above 4000 m and no symptoms of HAPE). MAIN OUTCOME MEASURES: Presence of PFO determined by transesophageal echocardiography, estimated pulmonary artery pressure by Doppler echocardiography, and arterial oxygen saturation measured by pulse oximetry in HAPE-susceptible and HAPE-resistant participants at low (550 m) and high altitude (4559 m). RESULTS: The frequency of PFO was more than 4 times higher in HAPE-susceptible than in HAPE-resistant participants, both at low altitude (56% vs 11%, P = .004; odds ratio [OR], 10.9 [95% confidence interval {CI}, 1.9-64.0]) and high altitude (69% vs 16%, P = .001; OR, 11.7 [95% CI, 2.3-59.5]). At high altitude, mean (SD) arterial oxygen saturation prior to the onset of pulmonary edema was significantly lower in HAPE-susceptible participants than in the control group (73% [10%] vs 83% [7%], P = .001). Moreover, in the HAPE-susceptible group, participants with a large PFO had more severe arterial hypoxemia (65% [6%] vs 77% [8%], P = .02) than those with smaller or no PFO. CONCLUSIONS: Patent foramen ovale was roughly 4 times more frequent in HAPE-susceptible mountaineers than in participants resistant to this condition. At high altitude, HAPE-susceptible participants with a large PFO had more severe hypoxemia. We speculate that at high altitude, a large PFO may contribute to exaggerated arterial hypoxemia and facilitate HAPE.

CD34-related coexpression of MDR1 and BCRP indicates a clinically resistant phenotype in patients with acute myeloid leukemia (AML) of older age

Clinical resistance to chemotherapy in acute myeloid leukemia (AML) is associated with the expression of the multidrug resistance (MDR) proteins P-glycoprotein, encoded by the MDR1/ABCB1 gene, multidrug resistant-related protein (MRP/ABCC1), the lung resistance-related protein (LRP), or major vault protein (MVP), and the breast cancer resistance protein (BCRP/ABCG2). The clinical value of MDR1, MRP1, LRP/MVP, and BCRP messenger RNA (mRNA) expression was prospectively studied in 154 newly diagnosed AML patients >or=60 years who were treated in a multicenter, randomized phase 3 trial. Expression of MDR1 and BCRP showed a negative whereas MRP1 and LRP showed a positive correlation with high white blood cell count (respectively, p < 0.05, p < 0.001, p < 0.001 and p < 0.001). Higher BCRP mRNA was associated with secondary AML (p < 0.05). MDR1 and BCRP mRNA were highly significantly associated (p < 0.001), as were MRP1 and LRP mRNA (p < 0.001) expression. Univariate regression analyses revealed that CD34 expression, increasing MDR1 mRNA as well as MDR1/BCRP coexpression, were associated with a lower complete response (CR) rate and with worse event-free survival and overall survival. When adjusted for other prognostic actors, only CD34-related MDR1/BCRP coexpression remained significantly associated with a lower CR rate (p = 0.03), thereby identifying a clinically resistant subgroup of elderly AML patients.

Increased genome instability in Escherichia coli lon mutants: relation to emergence of multiple-antibiotic-resistant (Mar) mutants caused by insertion sequence elements and large tandem genomic amplifications

Thirteen spontaneous multiple-antibiotic-resistant (Mar) mutants of Escherichia coli AG100 were isolated on Luria-Bertani (LB) agar in the presence of tetracycline (4 microg/ml). The phenotype was linked to insertion sequence (IS) insertions in marR or acrR or unstable large tandem genomic amplifications which included acrAB and which were bordered by IS3 or IS5 sequences. Five different lon mutations, not related to the Mar phenotype, were also found in 12 of the 13 mutants. Under specific selective conditions, most drug-resistant mutants appearing late on the selective plates evolved from a subpopulation of AG100 with lon mutations. That the lon locus was involved in the evolution to low levels of multidrug resistance was supported by the following findings: (i) AG100 grown in LB broth had an important spontaneous subpopulation (about 3.7x10(-4)) of lon::IS186 mutants, (ii) new lon mutants appeared during the selection on antibiotic-containing agar plates, (iii) lon mutants could slowly grow in the presence of low amounts (about 2x MIC of the wild type) of chloramphenicol or tetracycline, and (iv) a lon mutation conferred a mutator phenotype which increased IS transposition and genome rearrangements. The association between lon mutations and mutations causing the Mar phenotype was dependent on the medium (LB versus MacConkey medium) and the antibiotic used for the selection. A previously reported unstable amplifiable high-level resistance observed after the prolonged growth of Mar mutants in a low concentration of tetracycline or chloramphenicol can be explained by genomic amplification.