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Here, we report thermoelectric study of crossroads material MnTe via iso-electronic doping S on the Te-site. MnTe1-xSx samples with nominal S content of x=0.00, 0.05, and 0.10 were prepared using a melt-quench method followed by pulverization and spark plasma sintering. The X-ray powder diffraction, scanning electron microscopy, and ZAF-corrected compositional analysis confirmed that S uniformly substitutes Te up to slightly over 2%. A higher content of S in the starting materials led to the formation of secondary phases. The thermoelectric properties of MnTe1-xSx samples were characterized by means of Seebeck coefficient, electrical conductivity, and thermal conductivity measurements from 300K to 773K. Furthermore, Hall coefficient measurements and a single parabolic band model were used to help gain insights on the effects of S-doping on the scattering mechanism and the carrier effective mass. As expected, S doping not only introduced hole charge carriers but also created short-range defects that effectively scatter heat-carrying phonons at elevated temperatures. On the other hand, we found that S doping degraded the effective mass. As a result, the ZT of MnTe0.9S0.1 was substantially enhanced over the pristine sample near 400 K, while the improvement of ZT became marginal at elevated temperatures. A ZT~0.65 at 773K was obtained in all three samples. [ABSTRACT FROM AUTHOR]

Half-Heusler (HH) alloys have attracted considerable interest as promising thermoelectric (TE) materials in the temperature range around 700 K and above, which is close to the temperature range of most industrial waste heat sources. The past few years have seen nanostructuing play an important role in significantly enhancing the TE performance of several HH alloys. In this article, we briefly review the recent progress and advances in these HH nanocomposites. We begin by presenting the structure of HH alloys and the different strategies that have been utilized for improving the TE properties of HH alloys. Next, we review the details of HH nanocomposites as obtained by different techniques. Finally, the review closes by highlighting several promising strategies for further research directions in these very promising TE materials. [ABSTRACT FROM AUTHOR]

J. Neurochem. (2010) 115, 188-199. Impairment of the ubiquitin proteasome system (UPS) has been proposed to play an important role in the pathogenesis of Parkinson's disease (PD). Mice with UPS impairment in the nigra have been used for investigating mechanisms underlying neurodegeneration and for testing pre-clinical drugs to treat PD. However, the pathological, biochemical and behavioral features of UPS impairment animal model of PD have not been fully evaluated. For this purpose, we developed a UPS impairment model of nigral dopamine (DA) neuron degeneration by microinjection with proteasome inhibitors lactacystin, PSI or MG-132 into the medial forebrain bundle (iMFB) of C57BL/6 mice and then systematically examined the animal's locomotor activities, and various pathological and biochemical markers of PD. We found that lactacystin iMFB induced a sustained DA neuron degeneration, which can be reproduced by PSI iMFB and MG-132 iMFB. In the animal model, DA neuron degenerated preferentially in the substantia nigra, accompanied by profound inhibition of proteasomal activity, activation of caspase 3, elevated insoluble ubiquitin conjugates and α-synuclein positive inclusion-like granules, activated glia, and decreased motor activities. Thus, this model recapitulates many neuropathological and behavioral features of PD, rendering it likely suitable for studying the mechanisms of nigral DA neuron degeneration and for testing the potential anti-PD medications. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of multiscale nanostructured p-type (Bi,Sb)2Te3bulk materials by melt-spinning single elements of Bi, Sb, and Te followed by a spark plasma sintering process. The samples that were most optimized with the resulting composition (Bi0.48Sb1.52Te3) and specific nanostructures showed an increase of ∼50% or more in the figure of merit, ZT, over that of the commercial bulk material between 280 and 475 K, making it suitable for commercial applications related to both power generation and refrigeration. The results of high-resolution electron microscopy and small angle and inelastic neutron scattering along with corresponding thermoelectric property measurements corroborate that the 10−20 nm nanocrystalline domains with coherent boundaries are the key constituent that accounts for the resulting exceptionally low lattice thermal conductivity and significant improvement of ZT. [ABSTRACT FROM AUTHOR]

Chronic bacterial infection increased the risk of many solid malignancies and the underlying mechanism is usually ascribed to bacterial-caused inflammation. However, the direct interaction of infectious bacteria with cancer cells has been largely overlooked. We identified that highly metastatic breast cancer MDA-MB-231 cells expressed high level of Toll-like receptor 2 (TLR2) in contrast to poorly metastatic breast cancer cells and homogenous untransformed breast cells. TLR2 in MDA-MB-231 cells were actively triggered by peptidoglycan (PGN) from infectious bacterium Staphylococcus aureus (PGN-SA), resulting in the promoted invasiveness and adhesiveness of the cancer cells in vitro. PGN-SA induced phosphorylation of TAK1 and IkB in the TLR2-NF-κB pathway of the cancer cells and stimulated IL-6 and TGF-β secretion inMDA-MB-231 cells. All these effects were abrogated by TLR2 blockade. Further investigation showed that the NF-κB, STAT3 and Smad3 activities were augmented sequentially in MDA-MB-231 cells after PGN-SA stimulation. Phosphorylation of NF-κBp65 was initially increased and then followed by phosphorylation of STAT3 and Smad3 in the delayed 4 or 6 hours. NF-κB inhibition attenuated STAT3 and Smad3 activities whereas PGN-SAstimulated cell culture supernatants reversed these inhibitory effects. Our study indicated that TLR2 activation by infectious bacterial PGN played an important role in breast cancer cell invasiveness and illustrated a new link between infectious bacteria and the cancer cells, suggesting the importance of antibiotic therapy to treat cancer with bacterial infection. [ABSTRACT FROM AUTHOR]

Nigrostriatal neurodegeneration in Parkinson’s disease (PD) has been postulated to be caused by various pathological conditions, such as mitochondrial defects, oxidative stress, and ubiquitin-proteasome system (UPS) dysfunction. Pharmacological strategies designed to interfere with these pathological pathways may effectively counteract the degeneration. Rasagiline and selegiline are selective and irreversible monoamine oxidase-B inhibitors that possess significant protective properties on dopamine neurons in various pre-clinical models of PD. In the present study, the neuroprotective and neurorestorative effects of rasagiline and selegiline were compared in an animal model of PD produced by inhibition of the UPS. C57BL/6 male mice were microinjected bilaterally with UPS inhibitor lactacystin (1.25 μg/side), into the medial forebrain bundle. Administration of rasagiline (0.2 mg/kg, i.p. once per day) or selegiline (1 mg/kg, i.p. once per day), started 7 days before or after (up to 28 days) after lactacystin microinjection. We found that both rasagiline and selegiline exerted a significant neuroprotective effect against lactacystin-induced neurodegeneration; but only rasagiline managed to restore the nigrostriatal degeneration. Furthermore, rasagiline showed a modest protection against lactacystin-induced inhibition of proteasomal activity. Our study indicates that compared with selegiline, rasagiline is more potent in protecting neurodegeneration induced by UPS impairment and may, therefore, exert disease-modifying effects in PD. [ABSTRACT FROM AUTHOR]

Dysfunction of the ubiquitin-proteasome system (UPS) and accumulation of iron in substantia nigra (SN) are implicated in the pathogenesis of Parkinson's disease (PD). UPS dysfunction and iron misregulation may reinforce each other's contribution to the degeneration of dopamine (DA) neurons. In the present study, we use a new brain-permeable iron chelator, VK-28 [5-(4-(2-hydroxyethyl) piperazin-1-yl (methyl)-8-hydroxyquinoline], and its derivative M30 [5-(N-methyl-N-propargyaminomethyl)-8-hydroxyquinoline] in vivo to test their neuroprotective and neurorestorative properties against proteasome inhibitor (lactacystin) -induced nigrostriatal degeneration. Bilateral microinjections of lactacystin (1.25 µg/side) into the mouse medial forebrain bundle were performed. Administration of VK-28 (5 mg/kg, once a day) or M30 (5 mg/kg, once a day) was applied intraperitoneally 7 days before or after the lactacystin microinjection until the mice were sacrificed 28 days after microinjection. We found that VK-28 and M30 both significantly improved behavioral performances and attenuated lactacystin-induced DA neuron loss, proteasomal inhibition, iron accumulation, and microglial activation in SN. In addition, M30 restored the Bcl-2 level, which was suppressed after lactacystin injection. These findings suggest that brain-permeable iron chelators can improve DA neuron survival under UPS impairment. Furthermore, M30, a derivative of VK-28 and neuroprotective agent rasagiline, may serve as a better neuroprotective therapy for PD. [ABSTRACT FROM AUTHOR]

Analyzes the dynamic changes of the overlap efficiency, pump threshold power and laser slope efficiency for solid-state lasers. Cause of the increase in diffraction loss; Changes which cause the laser output to suddenly drop; Larger threshold pump power and a smaller total output power for a longer cavity; Space-dependent rate equations.

We report a melt spinning technique followed by a quick spark plasma sintering procedure to fabricate high-performance p-type Bi0.52Sb1.48Te3 bulk material with unique microstructures. The microstructures consist of nanocrystalline domains embedded in amorphous matrix and 5–15 nm nanocrystals with coherent grain boundary. The significantly reduced thermal conductivity leads to a state-of-the-art dimensionless figure of merit ZT∼1.56 at 300 K, more than 50% improvement of that of the commercial Bi2Te3 ingot materials. [ABSTRACT FROM AUTHOR]

The misfit-layered cobalt oxide [Ca2CoO3-δ][CoO2]1.62 is a promising material for high-temperature thermoelectric heat recovery. Here, we show that discrepancies in the numerously reported thermoelectric performances can result from Co3OM4 impurities or a change of the defects, i.e., the relative Co content in the [Ca2CoO3-δ][CoO2]1.62 phase. We observe that increasing the relative Co content in the [Ca2CoO3-δ][CoO2]1.62 phase leads to a larger figure of merit ZT. We attribute this increase of ZT to additional p-type charge carriers introduced by Ca vacancies and the resulting reduction of the electrical resistivity. For Co/Ca ratios above the miscibility limit, the increase in thermal conductivity due to the formation of Co3OM4 impurities leads to a reduction of ZT when the volume fraction of the Co3OM4 phase is increased from 1% to 3%. Hence, the best figure of merit is expected close to the upper phase boundary of the [Ca2CoO3-δ][CoO2]1.62 phase. [ABSTRACT FROM AUTHOR]

The thermoelectric performance of Ta substituted (ZrHf)NiSn-based half-Heusler compounds is studied. Here, Ta is used on the Hf site for controlling the charge carrier concentration in contrast to the widely used Sb substitution on the Sn site. The influence of the Ta content on the thermoelectric and transport properties of (Zr0.3Hf0.7-xTax)NiSn (x=0, 0.01, 0.05) is investigated by means of Seebeck coefficient, electrical resistivity, thermal conductivity, and Hall coefficient measurements. The results are analyzed in context of the single parabolic band model. Ta substitution increases the charge carrier concentration and suppresses the influence of impurity band, which is present in the pristine (Zr0.3Hf0.7)NiSn. Moreover, Ta substitution decouples and simultaneously increases the density-of-states effective mass (m*) and the charge carrier mobility (μ), leading to a larger weighted mobility μ·(m*)3/2. The lattice thermal conductivity is slightly suppressed due to increased point defect scattering. As a result, a Figure of Merit of 0.85 is achieved for (Zr0.3Hf0.65Ta0.05)NiSn compound at 870 K, ca. 180% improvement over the unsubstituted sample. [ABSTRACT FROM AUTHOR]

The thermoelectric performance of Ta substituted (ZrHf)NiSn-based half-Heusler compounds is studied. Here, Ta is used on the Hf site for controlling the charge carrier concentration in contrast to the widely used Sb substitution on the Sn site. The influence of the Ta content on the thermoelectric and transport properties of (Zr0.3Hf0.7-xTax)NiSn (x=0, 0.01, 0.05) is investigated by means of Seebeck coefficient, electrical resistivity, thermal conductivity, and Hall coefficient measurements. The results are analyzed in context of the single parabolic band model. Ta substitution increases the charge carrier concentration and suppresses the influence of impurity band, which is present in the pristine (Zr0.3Hf0.7)NiSn. Moreover, Ta substitution decouples and simultaneously increases the density-of-states effective mass (m*) and the charge carrier mobility (μ), leading to a larger weighted mobility μ(m*)3/2. The lattice thermal conductivity is slightly suppressed due to increased point defect scattering. As a result, a Figure of Merit of 0.85 is achieved for (Zr0.3Hf0.65Ta0.05)NiSn compound at 870 K, ca. 180% improvement over the unsubstituted sample. [ABSTRACT FROM AUTHOR]

The air-stable phosphide, Ag6Ge10P12, was synthesized from its elements in gram amounts. As its structure is closely related to high-performance thermoelectric tetrahedrites (Ag6Ge4Ge6P12 ≡ Cu6SSb4Cu6S12), we studied temperature dependent single-crystal X-ray diffraction experiments, quantum chemical calculations, and thermoelectric transport properties of spark plasma sintered and pristine, single crystalline samples, in order to give a comprehensive picture of its thermoelectric performance and its origin. The semiconducting character of this material is reflected in band structure calculations. Measurements of the thermal diffusivity exhibit a very low thermal conductivity, κ < 1 W m-1 K-1, which is close to a phonon glass-like behavior, and has its origin in a strong local bonding asymmetry, induced by strong bonding of the phosphorus-germanium (Ge4+) covalent framework and weak bonding of lone-pair electrons (Ge2+). This chemical bond hierarchy creates a pronounced anisotropic behavior of the silver atoms leading to low-frequency vibrations and thermal damping. Combining this with a moderate electrical resistivity (ρ ~ 15 mΩ cm) and a high Seebeck coefficient (S ~ 380 μV K-1) results in a remarkably high figure of merit (zT) of about 0.6 at 700 K. These results demonstrate that Ag6Ge10P12 is one of the best thermoelectric phosphides and a promising new platform for the future development of thermoelectrics. [ABSTRACT FROM AUTHOR]

The gonad specific expression of insulin-like growth factor 3 (igf3) has suggested an important role of igf3 in fish reproduction. In this study, medaka igf3 was isolated and its expression patterns were compared with igf1, and germ cell gene vasa in adult medaka ovary. Molecular cloning and sequencing showed that the open reading frame (ORF) of medaka igf3 was comprised of 501 nucleotides and encoded 166 amino acid residues. Reverse transcription polymerase chain reaction (RT-PCR) analysis showed that igf3 RNA was specifically expressed in developing embryos and adult gonads of both sexes. Real time quantitative PCR (q-PCR) indicated that igf3 expression was gradually increased during oogenesis, and reached its highest level at stage V. Using Chromogenic and fluorescent in situ hybridization, igf3 was shown to be present in the germ cells of oogonia and in oocytes at stages I-III, as well as abundant in granulosa cells and theca cells of oocytes at stages IV-V. In addition, igf3 and igf1 were expressed mutually in the outer theca cells of stage V oocytes in ovary. Collectively, we demonstrated that gonad specific igf3 could mark medaka ovarian somatic cells and germ cells. These findings highlight the importance of igf3 during ovarian development. [ABSTRACT FROM AUTHOR]

Pramipexole (PPX), a dopamine (DA) receptor D3 preferring agonist, has been used as monotherapy or adjunct therapy to treat Parkinson’s disease (PD) for many years. Several in vitro and in vivo studies in neurotoxin-induced DA neuron injury models have reported that PPX may possess neuroprotective properties. The present study is to evaluate the neuroprotection of PPX in a sustained DA neuron degeneration model of PD induced by ubiquitin–proteasome system (UPS) impairment. Adult C57BL/6 mice were treated with PPX (low dose 0.1 mg/kg or high dose 0.5 mg/kg, i.p, twice a day) started 7 days before, and continued after microinjection of proteasome inhibitor lactacystin in the medial forebrain bundle for a total 4 weeks. Animal behavior observation, and pathological and biochemical assays were conducted to determine the neuroprotective effects of PPX. We report here that PPX treatment significantly improves rotarod performance, attenuates DA neuron loss and striatal DA reduction, and alleviates proteasomal inhibition and microglial activation in the substantia nigra of lactacystin-lesioned mice. PPX can increase the levels of brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor and induce an activation of autophagy. Furthermore, pretreatment with D3 receptor antagonist U99194 can significantly block the PPX-mediated neuroprotection. These results suggest that multiple molecular pathways may be attributed to the neuroprotective effects of PPX in the UPS impairment model of PD. [ABSTRACT FROM AUTHOR]

New ceramic Ca3Co3.9O9+δ ?/CaMn0.97W0.03O3-δ thermoelectric generators with different cross section areas Ap and An of the p- and the n-type leg are fabricated, characterized, and tested at high temperatures in long-term tests. The variation of the measured power output and the efficiency with changing Ap/An ratio is discussed and compared with calculations based on the measured material properties. The highest conversion efficiencies are reached for ratios close to the one predicted by the compatibility approach, whereas an improper choice of Ap/An leads to a strong reduction of the efficiency. A volume power density of 1.4?W/cm3 and an efficiency of 1.08% are found for the most promising generator (temperature difference ΔT = 734?K and Ap/An = 1.12). The results reveal the major importance of the Ap/An ratio for the conversion efficiency and subsequently cost and weight reduction issues, both crucial for a large scale application of thermoelectric converters. Additionally, the oxide generators proved to be very reliable, as after more than 110?h of high temperature energy conversion, no degradation is observable. [ABSTRACT FROM AUTHOR]

Electronic and transport properties of Bi2S3 with various dopants are studied using density functional theory and experimental characterizations. First, principle calculations of thermoelectric properties are used to evaluate the thermoelectric potential of the orthorhombic Bi2S3 structure. The computational screening of extrinsic defects is used to select the most favorable n-type dopants. Among all the dopants considered, hafnium and chlorine are identified as prospective dopants, whereas, e.g., germanium is found to be unfavorable. This is confirmed by experiment. Seebeck coefficient (S) and electrical conductivity (σ) measurements are performed at room temperature on pellets obtained by spark plasma sintering. An increase of power factors (S2·σ) from around 50 up to 500 μW K-2m-1 is observed for differently doped compounds. In several series of samples, we observed an optimum of power factor above 500 μW K-2m-1 at room temperature for a chlorine equivalence of 0.25 mol. % BiCl3. The obtained results are plotted on a semilogarithmic log (r) versus S graph to demonstrate that a very strong linear trend that limits the power factor around 500 μW K-2m-1 exists. Further improvement of Bi2S3 as thermoelectric material will require finding new doping modes that will break through the observed trend. The results of stability tests demonstrate that properties of optimally doped Bi2S3 are stable. [ABSTRACT FROM AUTHOR]

It has been suggested that renal denervation (RD) may attenuate left ventricular (LV) hypertrophy. However, the role that autophagy serves in this process is currently unclear. In the present study, utilizing a model of hypertension-induced cardiac hypertrophy in spontaneous hypertensive rats, it was demonstrated that RD was significantly associated with a reduction in LV hypertrophy. Furthermore, a decrease in the myocardial mRNA of hypertrophy-associated genes was demonstrated in RD rats compared with sham controls. In addition, RD in hypertension-induced LV hypertrophy rats was associated with the attenuation of cellular autophagic response over activation at a physiological level. This was indicated by a reduction in the expression of Beclin-1, autophagy related 9A and microtubule-associated protein 1A/1B-light chain 3 II/I in RD rats to physiological levels that are observed in control rats. Furthermore, the number of autophagosomes was restored to physiological levels in the cardiomyocytes of RD rats. The results of the current study suggest that RD may attenuate LV hypertrophy via the regulation of autophagic responses. [ABSTRACT FROM AUTHOR]

A two-step process combining pulsed laser deposition of calcium cobaltite thin films and a subsequent laser induced forward transfer as micro-pixel is demonstrated as a direct writing approach of micro-scale thin film structures for potential applications in thermoelectric micro-devices. To achieve the desired thermo-electric properties of the cobaltite thin film, the laser induced plasma properties have been characterized utilizing plasma mass spectrometry establishing a direct correlation to the corresponding film composition and structure. The introduction of a platinum sacrificial layer when growing the oxide thin film enables a damage-free laser transfer of calcium cobaltite thereby preserving the film composition and crystallinity as well as the shape integrity of the as-transferred pixels. The demonstrated direct writing approach simplifies the fabrication of micro-devices and provides a large degree of flexibility in designing and fabricating fully functional thermoelectric micro-devices. [ABSTRACT FROM AUTHOR]

(TiZrHf)NiSn half-Heusler compounds were prepared by arc melting and their thermoelectric properties characterized in the temperature range between 325 K and 857 K, resulting in a Figure of Merit ZT ≈ 0.45. Furthermore, the prepared samples were used to construct a unileg module. This module was characterized in a homemade thermoelectric module measurement stand and yielded 275 mW/cm2 and a maximum volumetric power density of 700 mW/cm3. This was reached using normal silver paint as a contacting material; from an improved contacting, much higher power yields are to be expected. [ABSTRACT FROM AUTHOR]

Recent studies suggest that microglia over-expressing mutant human superoxide dismutase (mSOD1G93A) may contribute to motoneuron death in a transgenic mouse model of familial amyotrophic lateral sclerosis. To further assess the relative neurotoxicity of wild-type microglia, mSOD1G93A microglia, and microglia over-expressing wild-type human SOD1, we used primary cultures of microglia and motoneurons in the presence and absence of lipopolysaccharide stimulation. Following activation with lipopolysaccharide, mSOD1G93A microglia released more nitric oxide, more superoxide, and less insulin-like growth factor-1 than wild-type microglia. In microglia/motoneuron co-cultures, mSOD1G93A microglia induced more motoneuron death and decreased neurite numbers and length compared with wild-type microglia. Mutant SOD1G93A microglia also induced more motoneuron injury than microglia over-expressing wild-type human SOD1 in microglia/motoneuron co-cultures. Motoneuron survival was inversely correlated with nitrate + nitrite concentrations in mSOD1G93A co-cultures, suggesting the important role of nitric oxide in microglia-induced motoneuron injury. Thus, relative to wild-type microglia, mSOD1G93A microglia were more neurotoxic and induced more motoneuron injury than similarly treated wild-type microglia. [ABSTRACT FROM AUTHOR]

Knocking out of Nurr1 gene, a member of nuclear receptor superfamily, causes selective agenesis of dopaminergic neurons in midbrain. Reduced expression of Nurr1 increases the vulnerability of mesencephalic dopamine neurons to dopaminergic toxins. We evaluated the role of nitric oxide as a possible mechanism for this increased susceptibility. Increased expression of neuronal nitric oxide synthase and increased 3-nitrotyrosine were observed in striatum of Nurr1 heterozygous (Nurrl +/-) mice as compared with wild-type. Increased cytochrome C activation and consecutive release of Smac/DIABLO were also observed in Nurrl +/- mice. An induction of active Caspase-3 and p53, cleavage of poly-ADP (RNase) polymerase and reduced expression of bcl-2 were observed in Nurrl +/- mice. Methamphetamine significantly increased these markers in Nurrl +/- mice as compared with wild-type. The present data therefore suggest that nitric oxide plays a role as a modulating factor for the increased susceptibility, but not the potentiation, of the dopaminergic terminals in Nurr1 +/- mice. We also report that this increased neuronal nitric oxide synthase expression and increased nitration in Nurrl +/- mice led to the activation of apoptotic cascade via the differential alterations in the DNA binding activity of transcription factors responsible for the propagation of growth arrest as well as apoptosis. [ABSTRACT FROM AUTHOR]