bluuebunny/crossref_metadata_2025 huggingface dataset:
Dictyostelium possesses highly diverged presenilin/γ-secretase that regulates growth and cell-fate specification and can accurately process human APP: a system for functional studies of the presenilin/γ-secretase complex
Authors: McMains Vanessa C. , Myre Michael , Kreppel Lisa , Kimmel Alan R.
Published: August 2010

Presenilin (PS) is the catalytic moiety of the γ-secretase complex. PS and other γ-secretase components are well conserved among metazoa, but their presence and function in more-distant species are not resolved. Because inappropriate γ-secretase processing of amyloid precursor protein (APP) in humans is associated with familial Alzheimer’s disease, understanding essential elements within each γ-secretase component is crucial to functional studies. Diverged proteins have been identified in primitive plants but experiments have failed to demonstrate γ-secretase activity. We have identified highly diverged orthologs for each γ-secretase component in the ancient eukaryote Dictyostelium, which lacks equivalents of APP, Notch and other characterized PS/γ-secretase substrates. We show that wild-type (WT) Dictyostelium is capable of amyloidogenic processing of ectopically expressed human APP to generate amyloid-β peptides Aβ40 and Aβ42; strains deficient in γ-secretase cannot produce Aβ peptides but accumulate processed intermediates of APP that co-migrate with the C-terminal fragments α- and β-CTF of APP that are found in mammalian cells. We further demonstrate that Dictyostelium requires PS for phagocytosis and cell-fate specification in a cell-autonomous manner, and show that regulation of phagocytosis requires an active γ-secretase, a pathway suggested, but not proven, to occur in mammalian and Drosophila cells. Our results indicate that PS signaling is an ancient process that arose prior to metazoan radiation, perhaps independently of Notch. Dictyostelium might serve to identify novel PS/γ-secretase signaling targets and provide a unique system for high-throughput screening of small-molecule libraries to select new therapeutic targets for diseases associated with this pathway.
A linear systems analysis of the yaw dynamics of a dynamically scaled insect model
Authors: Dickson William B. , Polidoro Peter , Tanner Melissa M. , Dickinson Michael H.
Published: August 2010

Recent studies suggest that fruit flies use subtle changes to their wing motion to actively generate forces during aerial maneuvers. In addition, it has been estimated that the passive rotational damping caused by the flapping wings of an insect is around two orders of magnitude greater than that for the body alone. At present, however, the relationships between the active regulation of wing kinematics, passive damping produced by the flapping wings and the overall trajectory of the animal are still poorly understood. In this study, we use a dynamically scaled robotic model equipped with a torque feedback mechanism to study the dynamics of yaw turns in the fruit fly Drosophila melanogaster. Four plausible mechanisms for the active generation of yaw torque are examined. The mechanisms deform the wing kinematics of hovering in order to introduce asymmetry that results in the active production of yaw torque by the flapping wings. The results demonstrate that the stroke-averaged yaw torque is well approximated by a model that is linear with respect to both the yaw velocity and the magnitude of the kinematic deformations. Dynamic measurements, in which the yaw torque produced by the flapping wings was used in real-time to determine the rotation of the robot, suggest that a first-order linear model with stroke-average coefficients accurately captures the yaw dynamics of the system. Finally, an analysis of the stroke-average dynamics suggests that both damping and inertia will be important factors during rapid body saccades of a fruit fly.
Ubiquitous presence of the hammerhead ribozyme motif along the tree of life
Authors: de la Peña Marcos , García-Robles Inmaculada
Published: August 2010

Examples of small self-cleaving RNAs embedded in noncoding regions already have been found to be involved in the control of gene expression, although their origin remains uncertain. In this work, we show the widespread occurrence of the hammerhead ribozyme (HHR) motif among genomes from the Bacteria, Chromalveolata, Plantae, and Metazoa kingdoms. Intergenic HHRs were detected in three different bacterial genomes, whereas metagenomic data from Galapagos Islands showed the occurrence of similar ribozymes that could be regarded as direct relics from the RNA world. Among eukaryotes, HHRs were detected in the genomes of three water molds as well as 20 plant species, ranging from unicellular algae to vascular plants. These HHRs were very similar to those previously described in small RNA plant pathogens and, in some cases, appeared as close tandem repetitions. A parallel situation of tandemly repeated HHR motifs was also detected in the genomes of lower metazoans from cnidarians to invertebrates, with special emphasis among hematophagous and parasitic organisms. Altogether, these findings unveil the HHR as a widespread motif in DNA genomes, which would be involved in new forms of retrotransposable elements.
Addressing metacognitive capacity for self reflection in the psychotherapy for schizophrenia: A conceptual model of the key tasks and processes
Authors: Lysaker Paul H. , Buck Kelly D. , Carcione Antonino , Procacci Michelle , Salvatore Giampaolo , Nicolò Guiseppe , Dimaggio Giancarlo
Published: August 2010

Purpose. Recognition that recovery from schizophrenia may involve a deepening of the experience of being in the world has led to the possibility that psychotherapy may play a key role in treatment by enhancing metacognition, or the capacity to think about thinking. While the potential of psychotherapy to enhance metacognition in non‐psychotic disorders has been discussed in depth, little has been written about how psychotherapy may systematically address metacognition in schizophrenia. Accordingly, the current paper formulates a model of how psychotherapy might address one specific element of metacognition, namely self‐reflectivity.

Methods. Procedures are outlined for assessing clients' capacity for self‐reflectivity within narrative contexts during psychotherapy.

Results. Targeted interventions are identified which are tailored to clients' capacities in the moment and which assist clients to think about their own thinking at the level of which they are capable. This may lead clients over time to develop a greater ability to engage in acts of increasingly complex self‐reflectivity.

Conclusions. Individual psychotherapy can be modified and utilized to assist persons with schizophrenia to move towards recovery by assisting them to develop the capacity for self‐reflectivity. This may lead to clients having a fuller experience of themselves as a being in the world with a richer and more coherent personal narrative.
Non-genomic action of TCDD to induce inflammatory responses in HepG2 human hepatoma cells and in liver of C57BL/6J mice
Authors: Li Wen , Vogel Christoph F.A. , Wu Dalei , Matsumura Fumio
Published: August 2010

To assess the significance of the non-genomic signaling of TCDD (=dioxin) on liver of C57BL/6 mice and HepG2 human hepatoma cells, we first determined the group of markers that are susceptible to inhibition by parthenolide, a compound known to specifically suppress NF-κB-mediated inflammation. Of those, the most consistent marker turned out to be SOCS3 (a suppressor of cytokine signaling) known to respond to inflammation. An early diagnostic test on the action of TCDD on HepG2 cellsin vitrowithin 3–6 h indicated that Cox-2 and SOCS3 are mainly induced via a non-genomic route, whereas PAI-2 appears to be induced through the classical action route. More detailed diagnostic tests at later stages of action of TCDD in HepG2 cells revealed that induction of IL-1β, BAFF, and iNOS are largely mediated by the protein kinase-dependent non-genomic route. Anin vivostudy on the 7 day action of TCDD on liver of AhRNLSmice showed that several early markers (e.g., Cox-2, MCP-1 and SOCS3) are induced, but not late markers such as IL-1β. Together, these results show that the non-genomic pathway contributes significantly to the early stress response reactions to TCDD that includes inflammation in hepatoma cells as well as in the liver.
Increased γ-glutamyltransferase and decreased total bilirubin are associated with metabolic syndrome in Korean postmenopausal women
Authors: Kim Sang-Hwan , Lee Ji-Won , Im Jee-Aee , Hwang Hee-Jin
Published: August 2010

Background: The objective of this study was to determine if there is an association between serum hepatic markers and the metabolic syndrome in postmenopausal women.

Methods: This study involved 1229 postmenopausal women aged 44–85 years, who visited the Center for Health Promotion for a health check-up. We excluded subjects from the analysis if they had a daily alcohol consumption of more than 1.5 drinks (alcohol consumption ≥20 g/day) or had chronic viral hepatitis. We also excluded subjects who had abnormal hepatic function, as defined by serum aspartate aminotransferase (AST) or alanine aminotransferase (ALT) >100 IU/L, serum γ-glutamyltransferase (GGT) >100 IU/L, or serum total bilirubin concentrations >2 mg/dL.

Results: Serum ALT and GGT concentrations increased in proportion to the number of elements of the metabolic syndrome (p<0.01). However, total bilirubin concentrations decreased (p=0.01). After adjusting for age, body mass index, and the presence of fatty liver in the patients with metabolic syndrome, the odds ratios (95% confidence interval) were 1.38 (0.89–2.15) for log (ALT), 1.69 (1.30–2.20) for log (GGT), and 0.53 (0.33–0.86) for log (total bilirubin).

Conclusions: We found that an increase in GGT and a decrease in total bilirubin was associated with metabolic syndrome in postmenopausal women. Hepatic enzymes could be proposed as simple clinical metabolic markers that identify the metabolic syndrome.

Clin Chem Lab Med 2010;48:1623–8.
Biochemical markers of particle induced osteolysis in C57BL/6 mice
Authors: Kauther Max D. , Zimmermann Christina , Bachmann Hagen , Broecker-Preuss Martina , Hilken Gero , von Knoch Marius , Wedemeyer Christian
Published: August 2010

Background:Micro-structural changes associated with ultra high molecular weight polyethylene particle (UHMWPE) induced osteolysis, the most frequent cause of aseptic loosening, have been intensively investigated in the mammalian calvarian model by histomorphometry and micro-computed tomography. However, little is known regarding the serological changes that occur during this process.

Methods:Serological parameters for bone metabolism [calcium, phosphate, osteocalcin (OCN), deoxypyridinoline (DPD)/creatinine, alkaline phosphatase, osteoprotegerin and receptor activator of nuclear factor-κB] were analyzed in this animal model for particle induced osteolysis. Ten C57BL/6 mice were divided at random into sham operated and UHM-WPE implanted groups. Blood and urine samples were collected prior to and at 14 days after surgery.

Results:Implantation of UHMWPE lead to a significant decrease in bone volume (p=0.027). Both groups (sham/UHMWPE) showed a significant increase in calcium (p=0.004/p=0.027) and phosphate (p=0.001/p=0.001), without correlation to particle implantation. Significantly higher concentrations of DPD/creatinine (p=0.034) and OCN (p=0.022) were found after implantation of UHM-WPE. In addition, parameters could not be correlated to particle induced osteolysis.

Conclusions:DPD can be regarded as a valuable parameter for detecting UHMWPE induced osteolysis in the calvarian model. Further studies of serum parameters should focus on the clinical relevance in aseptic prosthetic loosening.

Clin Chem Lab Med 2010;48:1641–6.
Association between thyroid hormones, lipids and oxidative stress biomarkers in overt hypothyroidism
Authors: Santi Adriana , Duarte Marta Maria Medeiros Frescura , Moresco Rafael Noal , Menezes Charlene , Bagatini Margarete Dulce , Schetinger Maria Rosa Chitolina , Loro Vania Lucia
Published: August 2010

Background: The aim of this study was to investigate the effect of hypothyroidism on lipid peroxidation and the antioxidant profile, as well as to evaluate the interaction between thyroid hormones and biomarkers of oxidative stress in patients with overt hypothyroidism. We also evaluated the influence of cholesterol concentrations on biomarkers of oxidative stress in these same patients.

Methods: Total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), and vitamin E were measured in 20 subjects with overt hypothyroidism (OH) and 20 controls.

Results: TC, LDL cholesterol, triglycerides, TBARS, SOD, CAT, and vitamin E were significantly higher in the OH group. Significant correlation was observed for TSH and SOD, CAT, vitamin E and TBARS. Correlation was observed for triiodothyronine (T3) and SOD, CAT, vitamin E and TBARS. Significant correlation was also observed for free thyroxine and vitamin E and TBARS. However, correlation between T3 and CAT remained significant after controlling for TC concentrations.

Conclusions: Overt hypothyroidism is associated with an increase in oxidative stress, and hypercholesterolemia has a stronger influence on development of oxidative stress in hypothyroid conditions compared with thyroid hormones.

Clin Chem Lab Med 2010;48:1635–9.
An on-line solid phase extraction procedure for the routine quantification of urinary methylmalonic acid by liquid chromatography-tandem mass spectrometry
Authors: Kirchhoff Fabian , Lorenzl Stephan , Vogeser Michael
Published: August 2010

Background: The goal of this study was to develop and to validate an improved isotope-dilution-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of methylmalonic acid (MMA) in urine.

Methods: A previously described sample preparation protocol requires two solvent extraction steps, including evaporation. The first extraction is to extract the analyte from the sample, and second occurs following derivatization of the extract. In the method described here, the second evaporation step was substituted by on-line solid phase extraction employing column-switching and a permanent co-polymer based extraction cartridge. A standard validation protocol was applied to investigate the performance of the method.

Results: The method was found to be linear in the clinically relevant range of concentrations (6–100 μmol/L). Total coefficients of variation were below 10% and inaccuracy was <10% for quality control samples at three concentrations.

Conclusions: By omitting one evaporation step, the semi-automated method described in this article enables for more convenient work-flow in the quantification of urinary MMA compared to the previous protocol. This is of relevance for MMA measurement in the routine clinical laboratory setting. Validation demonstrated acceptable analytical performance.

Clin Chem Lab Med 2010;48:1647–50.
Impact of glucuronide interferences on therapeutic drug monitoring of posaconazole by tandem mass spectrometry
Authors: Krüger Ralf , Vogeser Michael , Burghardt Stephan , Vogelsberger Rita , Lackner Karl J.
Published: August 2010

Background: Posaconazole is a novel antifungal drug for oral application intended especially for therapy of invasive mycoses. Due to variable gastrointestinal absorption, adverse side effects, and suspected drug-drug interactions, therapeutic drug monitoring (TDM) of posaconazole is recommended.

Method: A fast ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of posaconazole with a run-time <3 min was developed and compared to a LC-MS/MS method and HPLC method with fluorescence detection.

Results: During evaluation of UPLC-MS/MS, two earlier eluting peaks were observed in the MRM trace of posaconazole. This was only seen in patient samples, but not in spiked calibrator samples. Comparison with LC-MS/MS disclosed a significant bias with higher concentrations measured by LC-MS/MS, while UPLC-MS/MS showed excellent agreement with the commercially available HPLC method. In the LC-MS/MS procedure, comparably wide and left side shifted peaks were noticed. This could be ascribed to in-source fragmentation of conjugate metabolites during electrospray ionisation. Precursor and product ion scans confirmed the assumption that the additional compounds are posaconazole glucuronides. Reducing the cone voltage led to disappearance of the glucuronide peaks. Slight modification of the LC-MS/MS method enabled separation of the main interference, leading to significantly reduced deviation.

Conclusions: These results highlight the necessity to reliably eliminate interference from labile drug metabolites for correct TDM results, either by sufficient separation or selective MS conditions. The presented UPLC-MS/MS method provides a reliable and fast assay for TDM of posaconazole.

Clin Chem Lab Med 2010;48:1723–31.
Proatrial natriuretic peptide is a better predictor of 28-day mortality in septic shock patients than proendothelin-1
Authors: Guignant Caroline , Venet Fabienne , Voirin Nicolas , Poitevin Françoise , Malcus Christophe , Bohé Julien , Lepape Alain , Monneret Guillaume
Published: August 2010

Background: Septic shock is a major health care problem that affects a heterogeneous population of patients. To improve sepsis management, a key point is to decrease this heterogeneity by stratifying patients according to specific criteria, such as appropriate biomarkers. As the early phase of septic shock is characterized by cardiovascular dysfunction, precursors of vasoactive hormones represent interesting candidates. The objective of the present study was to concomitantly assess the predictive value of C-terminal proendothelin-1 and midregional proatrial natriuretic peptide (CT-proET-1 and MR-proANP, respectively vasoconstrictor and vasodilator) on 28-day mortality following septic shock.

Methods: In this observational study which included 99 patients, concentrations of MR-proANP and CT-proET-1 were measured using an immunoluminometric assay three times within the first week after the onset of septic shock.

Results: While MR-proANP concentrations were significantly increased in non-survivors in comparison with survivors, no differences were noted for CT-proET-1. Increased MR-proANP concentrations were significantly associated with mortality after both univariate and multivariate analyses, adjusted for usual clinical confounders [SAPS II (simplified acute physiology score II), SOFA (sepsis-related organ failure assessment) scores and number of co-morbidities].

Conclusions: In septic shock patients, MR-proANP appears to be a good predictor of 28-day mortality, whereas CT-proET-1 does not present any predictive value during monitoring.

Clin Chem Lab Med 2010;48:1813–20.
On the shortest identity in finite simple groups of Lie type
Authors: Hadad Uzy
Published: August 2010

We prove that the length of the shortest identity in a finite simple group of Lie type of rank
Character degree sums in finite nonsolvable groups
Authors: Magaard Kay , Tong-Viet Hung P.
Published: August 2010

Let
Monoamine Oxidases Regulate Telencephalic Neural Progenitors in Late Embryonic and Early Postnatal Development
Authors: Cheng Aiwu , Scott Anna L. , Ladenheim Bruce , Chen Kevin , Ouyang Xin , Lathia Justin D. , Mughal Mohamed , Cadet Jean Lud , Mattson Mark P. , Shih Jean C.
Published: August 2010

Monoamine neurotransmitters play major roles in regulating a range of brain functions in adults and increasing evidence suggests roles for monoamines in brain development. Here we show that mice lacking the monoamine metabolic enzymes MAO A and MAO B (MAO AB-deficient mice) exhibit diminished proliferation of neural stem cells (NSC) in the developing telencephalon beginning in late gestation [embryonic day (E) 17.5], a deficit that persists in neonatal and adult mice. These mice showed significantly increased monoamine levels and anxiety-like behaviors as adults. Assessments of markers of intermediate progenitor cells (IPC) and mitosis showed that NSC in the subventricular zone (SVZ), but not in the ventricular zone, are reduced in MAO AB-deficient mice. A developmental time course of monoamines in frontal cortical tissues revealed increased serotonin levels as early as E14.5, and a further large increase was found between E17.5 and postnatal day 2. Administration of an inhibitor of serotonin synthesis (parachlorophenylalanine) between E14.5 and E19.5 restored the IPC numbers and SVZ thickness, suggesting the role of serotonin in the suppression of IPC proliferation. Studies of neurosphere cultures prepared from the telencephalon at different embryonic and postnatal ages showed that serotonin stimulates proliferation in wild-type, but not in MAO AB-deficient, NSC. Together, these results suggest that a MAO-dependent long-lasting alteration in the proliferation capacity of NSC occurs late in embryonic development and is mediated by serotonin. Our findings reveal novel roles for MAOs and serotonin in the regulation of IPC proliferation in the developing brain.
Neural Mechanisms of Belief Inference during Cooperative Games
Authors: Yoshida Wako , Seymour Ben , Friston Karl J. , Dolan Raymond J.
Published: August 2010

Humans have the arguably unique ability to understand the mental representations of others. For success in both competitive and cooperative interactions, however, this ability must be extended to include representations of others' belief about our intentions, their model about our belief about their intentions, and so on. We developed a “stag hunt” game in which human subjects interacted with a computerized agent using different degrees of sophistication (recursive inferences) and applied an ecologically valid computational model of dynamic belief inference. We show that rostral medial prefrontal (paracingulate) cortex, a brain region consistently identified in psychological tasks requiring mentalizing, has a specific role in encoding the uncertainty of inference about the other's strategy. In contrast, dorsolateral prefrontal cortex encodes the depth of recursion of the strategy being used, an index of executive sophistication. These findings reveal putative computational representations within prefrontal cortex regions, supporting the maintenance of cooperation in complex social decision making.
Sensory Input Drives Multiple Intracellular Information Streams in Somatosensory Cortex
Authors: Alenda Andrea , Molano-Mazón Manuel , Panzeri Stefano , Maravall Miguel
Published: August 2010

Stable perception arises from the interaction between sensory inputs and internal activity fluctuations in cortex. Here we analyzed how different types of activity contribute to cortical sensory processing at the cellular scale. We performed whole-cell recordings in the barrel cortex of anesthetized rats while applying ongoing whisker stimulation and measured the information conveyed about the time-varying stimulus by different types of input (membrane potential) and output (spiking) signals. We found that substantial, comparable amounts of incoming information are carried by two types of membrane potential signal: slow, large (up–down state) fluctuations, and faster (>20 Hz), smaller-amplitude synaptic activity. Both types of activity fluctuation are therefore significantly driven by the stimulus on an ongoing basis. Each stream conveys essentially independent information. Output (spiking) information is contained in spike timing not just relative to the stimulus but also relative to membrane potential fluctuations. Information transfer is favored in up states relative to down states. Thus, slow, ongoing activity fluctuations and finer-scale synaptic activity generate multiple channels for incoming and outgoing information within barrel cortex neurons during ongoing stimulation.
Adrenocortical carcinoma and pregnancy: clinical and biological features and prognosis
Authors: Abiven-Lepage Gwenaëlle , Coste Joël , Tissier Frédérique , Groussin Lionel , Billaud Line , Dousset Bertrand , Goffinet François , Bertagna Xavier , Bertherat Jérôme , Raffin-Sanson Marie-Laure
Published: August 2010

Objective

Adrenocortical carcinoma (ACC) is a rare, severe disease. Pregnancy-associated ACC has rarely been reported. We wished to evaluate the characteristics and prognosis of ACC diagnosed in patients during pregnancy or in thepostpartumperiod, comparing them with those for ACC diagnosed in nonpregnant women.

Design

Clinical presentation, hormonal secretion, staging, survival, and obstetric data are reported. Patients were included between 1963 and 2007. Mean follow-up was 48 months.

Patients and methods

This is a retrospective cohort study carried out at a referral center. All female patients aged 16–49 years diagnosed with ACC during the observation period were included (n=110). Twelve of these women were pregnant or in the first 6 months after delivery. Hormonal secretion, staging, obstetric data, and survival were analyzed. For the survival analysis, pregnant patients were compared with a subgroup of nonpregnant women matched for age, stage, and year of diagnosis (1 pregnant patient/2 controls).

Results

Adrenocortical tumors diagnosed during pregnancy or in thepostpartumperiod tend to be more often cortisol-secreting tumors (P=0.06) and to be discovered at a more advanced stage than those in nonpregnant women, although the differences were not significant. Fetal outcome was poor. Overall survival of the mother was worse than that of matched controls (hazard ratio of death: 3.98, confidence interval=1.34–11.85,P=0.013).

Conclusion

ACC diagnosed during pregnancy or in thepostpartumperiod is associated with a poor fetal outcome and a poorer prognosis than ACC diagnosed in nonpregnant women.
Evidence that high variation in antral follicle count during follicular waves is linked to alterations in ovarian androgen production in cattle
Authors: Mossa F , Jimenez-Krassel F , Folger J K , Ireland J L H , Smith G W , Lonergan P , Evans A C O , Ireland J J
Published: August 2010

Androgens have an important role in ovarian follicular growth and function, but circulating androgen concentrations are also associated with ovarian dysfunction, cardiovascular disease, and metabolic disorders in women. The extent and causes of the variation in androgen production in individuals, however, are unknown. Because thecal cells of follicles synthesize androstenedione and testosterone, variation in production of these androgens is hypothesized to be directly related to the inherently high variation in number of healthy growing follicles in ovaries of individuals. To test this hypothesis, we determined whether thecalCYP17A1mRNA (codes for a cytochrome P450 enzyme involved in androgen synthesis), LH-induced thecal androstenedione production, androstenedione concentrations in follicular fluid, and circulating testosterone concentrations were lower in cattle with relatively low versus high number of follicles growing during follicular waves and whether ovariectomy reduced serum testosterone concentrations. Results demonstrated that cattle with a low follicle number had lower (P<0.05) abundance ofCYP17A1mRNA in thecal cells, reduced (P<0.01) capacity of thecal cells to produce androstenedione in response to LH, lower (P<0.01) androstenedione concentrations in ovulatory follicles, and lower (P<0.02) circulating testosterone concentrations during estrous cycles compared with animals with high follicle number. Also, serum testosterone in cattle with low or high follicle number was reduced by 63 and 70%, respectively, following ovariectomy. In conclusion, circulating androgen concentrations are lower in cattle with low versus high number of follicles growing during follicular waves, possibly because of a reduced responsiveness of thecal cells to LH.
Microstructural, Electrical-, Magneto-Transport Properties of Grain Size Modulated Nanocrystalline Nd0.67Sr0.33MnO3 CMR Manganites
Authors: Paul S. , Nath T. K.
Published: August 2010

We have investigated the effect of nanometric grain sizes on Microstructural, electrical-, magneto-transport and magnetic behaviors in nanocrystalline Nd0.67Sr0.33MnO3 CMR manganites. Three nanocrystalline powders of Nd0.67Sr0.33MnO3 were synthesized through chemical route “Pyrophoric Reaction Process” and calcined for 5 hrs at calcinations temperature (TCal = 650°C, 750°C, and 850°C). XRD patterns indicate that all the synthesized powders have pseudo-cubic perovskite structure without any secondary impurity phase. Using Debye Scherrer formula we calculated the crystallites size for three nanocrystalline Nd0.67Sr0.33MnO3 powders (∼ 30, 40, and 54 nm for TCal = 650°C, 750°C, and 850°C respectively). TEM micrographs show that the average particle sizes are in nanometric regime (ψ ∼ 30–50 nm). In AC susceptibility and resistivity measurement we observed that there is an almost constant Curie temperature (TC) has value around 240 K and gradual decrease of metal-insulator transition temperature (TP) (from 200-129 K) with decrease of TCal. The magneto resistance of ultra fine nanoparticles increases with grain sizes. Highest magnetoresistance observed ∼ 24 for Nd0.67Sr0.33MnO3 with TCal = 850°C. Experimental results revels, the effect of nanometric grain sizes has an important impact in magnetic properties and magneto-transport behaviors.
Delta-phase manganese gallium on gallium nitride: a magnetically tunable spintronic system
Authors: Wang Kangkang , Chinchore Abhijit , Lin Wenzhi , Smith Arthur , Sun Kai
Published: August 2010

Ferromagnetic delta-phase manganese gallium with Mn:Ga ratio between 1:1 to 1.5:1 is grown on wurtzite gallium nitride and scandium nitride substrates, using molecular beam epitaxy. The dependencies of growth properties, e.g. interface formation, surface reconstruction and crystalline quality, on substrate crystallographic structure and polarity are investigated. Results suggest that for growth on wurtzite GaN, Ga-polar surface promotes quicker interface formation, and also results in better crystalline quality of the MnGa film, as compared to N-polar. The crystal orientation and magnetic anisotropy are found to be different than those grown on cubic scandium nitride substrates.
Synthesis and Magnetic Properties of Nanocomposite Magnets Self-Organized from FeB-Nd-Nb Metallic Glasses
Authors: Tamura R , Kobayashi S , Fukuzaki T , Kamiko M
Published: August 2010

ABSTRCT

Change of the magnetic property of Fe-B-Nd-Nb alloys was investigated with replacing Nb by a glass forming element Zr under constant quenching rate as well as heat treatment conditions. As a result, the coercivity significantly increases up to 1207 kA/m when the half of Nd is replaced by Zr, which is presumably due to grain refinement of the Nd2Fe14B phase. The self-organized nanograin magnets are attractive for future applications since their coercivity can be further improved by reducing the grain size via optimizing the Zr concentration, the quenching rate and the subsequent heat treatment condition.
Optical Properties and Thermal Effects in CaSZ and YSZ Single Crystal by Raman Scattering, Photoluminescence and Absorption Spectroscopy
Authors: Torres Dorcas I. , Llopis José
Published: August 2010

Temperature dependent Photoluminescence (PL) and Raman spectra have been used to study the defect structure of untreated and thermochemically reduced calcia stabilized zirconia (CaSZ) and yttria stabilized zirconia (YSZ) single crystals. Over the whole temperature range studied the emission (EM) spectrum of the untreated crystals can be decompose into three broad bands, indicating the presence of several radiative electron transitions which can be associated with anion vacancies centers. Results points out to intrinsic F type centers and extrinsic F type centers (FA, FAA) as the main defect generated in the stabilization process. Effect of thermal reduction on the Raman activity caused a decreased in the acoustic mode region and a shift in the maximum of the excitation (EX) spectra. These variations can be related to a broad absorption band centered at ∼365 nm. This is consistent with a nonrandom arrangement of vacancies, which produces the superposition of periodic sequences of vacancies within domains. Concentration of the color centers was determined by optical absorption in the UV-VIS region. PL temperature dependence study in colored samples suggest that no significant new defect was generated in the reduction process, but a recombination of the charges states of the initial intrinsic and extrinsic F centers.
An Assessment of Layer Development at the Fuel/Cladding Interface During Irradiation of Metallic SFR Fuel Elements
Authors: Keiser Dennis D. , Cole James I.
Published: August 2010

To investigate fuel cladding chemical interaction in irradiated metallic nuclear fuels, diffusion couple experiments have been performed using prototypic metallic fuel alloys with additions of noble metal and lanthanide fission product components mated against stainless steel claddings. The developed interdiffusion zones have been characterized using SEM/EDS/WDS to determine the development of phases and the interdiffusion behavior of specific fuel, cladding, and fission product components. The formed diffusion structures have been compared to actual interaction zones that form in irradiated metallic SFR fuels. This paper discusses how the structures compare between the diffusion couple-generated interdiffusion zones and those that develop in irradiated metallic nuclear fuels. It was found that similarities exist between the phase development and interdiffusion behavior in the annealed diffusion couples and the irradiated fuels. Nd, Mo, and Ru, which were added to a fuel alloy to represent fission products that are present in irradiated metallic nuclear fuels, were found to exhibit interdiffusion behavior in annealed diffusion couples that was similar to what has been observed in actual irradiated metallic fuels. This was also true for the original fuel components U, Pu, and Zr, along with the cladding constituent Fe, Ni, and Cr.
Thermodynamic Properties of Actinide Oxide Solid Solutions
Authors: Shuller Lindsay C. , Pavenayotin Niravun , Ewing Rodney C. , Becker Udo
Published: August 2010

Density functional theory and Monte(Carlo methods were used to investigate the solid( solution behavior of actinide dioxides (AcO2). The end(members of interest include: ZrO2, ThO2, UO2, NpO2, and PuO2; all have the isometric fluorite structure. Ab initio and subsequent Monte( Carlo simulations are used to calculate the excess enthalpy of mixing (ΔHexcess), excess Gibbs free energy of mixing (ΔGexcess), and excess configurational entropy (ΔSexcess) for the above solid(solution series. From ΔGexcess, phase diagrams are derived and miscibility gaps identified. All of the binaries of the aforementioned end(members were studied; however, this paper focuses on the U1(xZrxO2and Np1(xUxO2binaries. About 25 at.% Zr can be in solid solution with the UO2matrix above 1500 K, while Np is completely miscible in the UO2matrix. Partial cation ordering was observed at all temperatures for the U1(xZrxO2binary. The Np1(xUxO2binary approaches perfect cation disorder at high temperatures (2000 K). The cation ordering scheme is not identified in this study because the number of cation(cation interaction parameters was limited by the single unit cell from the ab initio calculations.
Site Occupation and Defect Structure of Fe2Nb Laves Phase in Fe-Nb-M Ternary Systems at Elevated Temperatures
Authors: Ishikawa Shigehiro , Matsuo Takashi , Takata Naoki , Takeyama Masao
Published: August 2010

For the Fe2Nb Laves phase with C14 structure in the Fe-Nb-M (M : Cr, Mn, Co, Ni) systems, the site occupation of M in Fe2Nb has been examined in terms of XRD Rietveld analysis, particularly paying attention to the two Fe sublattice sites of Fe1 (36-net in the triple layer : t) and Fe2 (kagome-net of the single layer : s) with the fraction of 0.25 and 0.75, respectively. In any these four ternary systems, the Fe2Nb Laves phase region largely extends along the equi-Nb concentration direction; for Mn complete solid solubility exists, and the solubility of Cr and Co in Fe2Nb is more than 50 at.% and that of Ni is 44 at.%. Thus, at least two thirds of all Fe sublattices in Fe2Nb are occupied by M in all cases. Rietveld analysis revealed that Cr and Mn with which have a larger atomic size than Fe prefer to occupy the Fe1 sublattice site when the amount in solution is less than 0.25 fraction of Fe in Fe2Nb and the preferred occupation site changes to the Fe2 sublattice site when the amount in solution increases beyond 0.25. In contrast, Co and Ni whose atomic size is smaller than Fe preferentially occupy the Fe2 sublattice site, regardless of the amount. The c/a ratio of stoichiometoric Fe2Nb increases and becomes closer to the ideal value (1.633) of the cubic C15 structure when the Fe1 sublattice site is occupied by Cr and Mn. However, the degree of symmetries of both tetrahedron and kagome-net formed by Fe atoms become better when Fe2 sublattice site is occupied by a certain amount of Ni.
Harmonic Analysis of AlN Piezoelectric Mesa Structures
Authors: Mazumdar Madhulika , Kabulski A. , Farrell R. , Kuchibhatla Sridhar , Pagán V. R. , Korakakis D
Published: August 2010

In this work we report the displacement response of piezoelectric Aluminum Nitride (AlN) thin film MESA in an electrical circuit consisting of a circular MESA in series with a resistance subjected to time varying electrical loads. ANSYS was utilized for the simulation of 3D piezoelectric structures; using coupled field analysis to understand the electro-mechanical behavior of AlN thin film mesas. ANSYS applies finite element analysis (FEM) method to simulate the transient piezoelectric trends. Ringing and overshoot effects were observed in the thin simulation results on applying pulse voltages of varying frequencies to the circuit. The fast rise time of the voltage pulse could be exciting these effects. The effect of fast rising pulse voltages on the RC time constant of the circuit is still unclear at this point and needs to be further investigated.
Integrative Chemistry Toward Designing Polyvinyl Alcohol/Poly-aniline/Vanadium Oxide Nanocomposite-based Macroscopic Fibers: 1D-Highly Sensitive Alcohol Sensors Bearing Enhanced Toughness
Authors: Brun Nicolas , Dexmer Julien , Leroy Céline M. , Sérier Hélène , Steunou Nathalie , Achard Marie-France , Backov Rénal
Published: August 2010

Polyvinyl alcohol/Poly-aniline/Vanadium Oxide nanocomposite-based macroscopic fibers have been generated by using a redox reaction addressed while performing an extrusion shaping process. The resulting composites have been thoroughly characterized via a large set of techniques such as SEM, SAXS, XRD and FTIR, in order to determine aniline effects over final materials' structures and properties. Thus, the perturbation of the preferential orientation of the V2O5 nano-ribbons toward the fiber main axis, induced by aniline Red-ox intercalation, has been observed. Also, the partial reduction of V5+ species to V4+ ones, due to the strongly oxidizing character of the first ones toward aniline, has been revealed by Electron Spin Resonance (ESR). Moreover, these fibers are able to detect 5 ppm of ethanol within 3-5 seconds at 42 °C, and possess a toughness of 12 J.g-1.
Photoluminescence Characterization of Hydrogenated Nanocrystalline/Amorphous Silicon
Authors: Fields Jeremy D , Taylor Craig , Radziszewski Juliuz George , Baker David , Yue Guozhen , Yan Baojie
Published: August 2010

The photoluminescence in a nc-Si/a-Si:H mixture has been investigated at varying excitation intensities, and temperatures We have also observed changes in the luminescence spectra, which are induced by sequential annealing at temperatures below the a-Si:H crystallization temperature (˜ 600°C). Two predominant luminescence peaks are observed at ˜ 0.95 eV and ˜ 1.30 eV, which are attributed to band tail-to-band tail transitions near the nc-Si grain boundaries and in the a-Si:H bulk, respectively. The 0.95 eV band saturates approaching 500 mW/cm2 excitation intensity. Annealing the nc-Si/a-Si:H mixture brings out a new low energy peak, centered at ˜ 0.70 eV, and which we believe to be due to oxygen defects.
Improvement of Quantum Efficiency of Amorphous Silicon Thin Film Solar Cells
Authors: Fang Liang , Im Jong-San , Park Sang-Il , Lim Koseng Su
Published: August 2010

The enhancement of optical transmittance at the air/glass interface of amorphous silicon thin film solar cells was shown by application of a nanoporous polymethyl methacrylate (PMMA) antireflection (AR) coating. The PMMA coating was prepared by spin coating of PMMA solution in chloroform in the presence of a small amount of nonane. Because of the difference of the vapor pressure of chloroform and nonane, phase separated structure formed after complete evaporation of both of them during spin coating process. The Corning 1737 glass with the AR coating has high transmittance near 95% from 450-1100nm wavelengths. The amorphous silicon solar cells with the nanoporous PMMA AR coating realize an improvement in quantum efficiency (QE) up to 4% in 450-650nm spectral regions.
Effects of Thinned Multi-Stacked Wafer Thickness on Stress Distribution in the Wafer-on-a-Wafer (WOW) Structure
Authors: Kitada Hideki , Maeda Nobuyuki , Fujimoto Koji , Suzuki Kousuke , Nakamura Tomoji , Ohba Takayuki
Published: August 2010

In the trough silicon via (TSV) structure for 3-dimensional integration (3DI), large thermal-mechanical stress acts in the TSV caused by the mismatch in thermal expansion coefficient (CTE) of the TSV materials. In this study, the stress of multi-stacked thin silicon wafers composed of copper TSV and copper/low-k BEOL structure was analyzed by the finite element method (FEM), aiming to reduce the stress of TSV of 3D-IC. The results of sensitivity analysis using design of experiment (DOE) indicated that the thickness of the silicon and adhesive layer are the key factors for the structural integration of TSV design.
Multi-Layered SiC Nanocrystals Embedded in SiO2 Dielectrics for Nonvolatile Memory Application
Authors: Lee Dong Uk , Lee Tae Hee , Kim Eun Kyu , Shin Jin-Wook , Cho Won-Ju
Published: August 2010

A nonvolatile memory device with the multi-layered SiC nanocrystals embedded in the SiO2 dielectrics for long-term data storage was fabricated and its electrical properties were evaluated. The SiC nanocrystals were formed by using post thermal annealing process. The transmission electron microscope analysis showed the multi-layered SiC nanocrystals between the tunnel and the control oxide layers. The average size and density of the SiC nanocrystals were approximately 5 nm and 2×1012 cm-2, respectively. The memory window of nonvolatile memory devices with the multi-layered of SiC nanocrystals was about 2.7 V during the operations at ±10 V for 700 ms, and then it was maintained around at 1.1 V after 105 sec.
Metastable Variations of the Fill Factor in CIGS Thin Film Solar Cells
Authors: Urbaniak Aleksander , Igalson Małgorzata
Published: August 2010

We investigate the origin of fill factor changes induced by reverse bias treatment. Evolution of current-voltage characteristics have been measured during application of reverse voltage bias. Two different cell behaviors have been identified. At elevated temperatures one kind of the devices strongly deteriorates and exhibit so called double diode behavior. On the other hand, in the same conditions another cells keep their fill factor almost constant. We correlate the fill factor changes with the kinetics of capacitance and show that although increased number of shallow acceptors itself cannot induce this severe FF deterioration, it may strongly influence position of the Fermi level at the heterointerface that in a presence of an electron barrier is crucial for the device behavior.
Photoluminescence and Photoluminescence Excitation Spectroscopy of Cu(In,Ga)Se2Thin Films
Authors: Hebert Damon N. , Soares Julio A. N. T. , Rockett Angus A.
Published: August 2010

The role of intrinsic point defects on radiative recombination in Cu(In,Ga)Se2thin films was investigated by photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies. Experiments were performed on device-grade polycrystalline layers and single crystal thin films. PL transitions identified by others as indicating a shallow state with an ionization energy of ∼16 meV is proposed to be a transition into band tail states rather than a distinct shallow defect. The presence of deep levels contributing to radiative recombination does not necessarily preclude the material from producing a high efficiency device and may suggest the absence of dominant non-radiative recombination pathways. The band edge width as measured by PLE and the separation of this edge from defect states are suggested to be potentially effective indicators of the quality of a material. Luminescence that appears to be connected with the absence of Na in the growth process persists in high Ga alloy, Na containing materials, suggesting that Na may become ineffective in passivating or eliminating certain defects in high Ga material.
Photocatalysis for the Degradation of Ionic Surfactants in Water: The Case of DPC
Authors: Naldoni Alberto , Bianchi Claudia , Ardizzone Silvia , Cappelletti Giuseppe , Ciceri Luca , Schibuola Alessandro , Pirola Carlo , Pappini Marco
Published: August 2010

Traditional techniques to remove contaminants (carbon adsorption, incineration, biological activity and chemical treatment) have a lot of disadvantages. Advanced Oxidation Processes (AOP’s) are used as alternative processes in the degradation of surfactants and in general for wastewater treatment. They are based on the generation of OH•, one of the most powerful oxidant known (E° = 2.73 V) and capable to react non-selectively with any organic compound. In the present work, the degradation of a cationic surfactant (dodecylpyridinium chloride (DPC)) was performed. The photodegradation reaction was investigated both in a slurry reactor and in a vessel where the photocatalyst (P25 by Degussa) was anchored onto an aluminum surface to avoid the final filtration of the powder at the end of the reaction. Moreover a new photoreactor was built on purpose to investigate the influence of the pressure on the degradation process.
Surface Plasmon Resonance with Electrospun Nanofibers on Gold Surface
Authors: Tsuboi Kazuma , Matsumoto Hidetoshi , Minagawa Mie , Tanioka Akihiko
Published: August 2010

In this paper we report new excitation method of surface plasmon polariton (SPP) at air/gold interface with electrospun nanofibers. Nanofibers of polyvinylpirrolidone were electrospun onto the surface of a gold film. The observations by scanning electron microscopy and optical microscopy indicated that the average diameters of the nanofibers were about 300 nm and average sizes of pores were about 30-40 μm. Optical response of the nanofibers on gold surface was investigated by polarized reflection absorption spectroscopy (RAS). The RAS spectrum with p-polarized light showed two absorption bands while the spectrum with s-polarized light only one band. One is a band at about 520 nm that also found in the spectrum with s-polarized light. Another is a broad band in the near-infrared region which found only with p-polarized light. The peak intensity of the latter band increases with increase of incident angle of the polarized light and the peak wavelength of the band shifted to longer wavelength. These responses suggested that SPP at air/gold interface was excited with the scattering light from the electrospun nanofibers. We also found that the peak wavelength of the absorption band in near-infrared region changed with the increase of the amount of the nanofibers. This may be due to the fact that the sizes of the pores on gold surface became smaller than the propagation length of SPP, which resulted in scattering and interference of SPP.