Good rectifying characteristic in p–n junctions composed of La0.67Ca0.33MnO3-δ/Nb–0.7 wt %-doped SrTiO3

Simple p–n junctions have been fabricated using a simple heteroepitaxial structure of La0.67Ca0.33MnO3–/Nb-doped SrTiO3. In such junctions, the La0.67Ca0.33MnO3– exhibits semiconductor behavior due to oxygen deficiency, whereas the Nb–0.7 wt %-doped SrTiO3 shows a metal behavior. These junctions demonstrate good rectifying characteristic in a wide temperature range from 5 to 350 K. An intriguing observation is that the rectifying behavior is nearly independent of temperature. © 2003 American Institute of Physics.published_or_final_versio

Doping effects on the phase separation in perovskite La0.67-xBixCa0.33MnO3

Effects of Bi, Cr, and Fe doping on phase separation of La0.67Ca0.33MnO3 have been experimentally studied. As proved by the electron-spin resonance and neutron-diffraction studies, partial replacement of La by Bi causes the simultaneous occurrence of ferromagnetic (FM) phase and charge-ordered antiferromagnetic phase. As a consequence, two subsequent magnetic transitions at ∼120 K and ∼230 K are resulted. A strong coupling between the coexisted phases is assumed, which is responsible for the insensitivity of Tc(L), the higher Curie temperature, to Bi doping after the appearance of phase separation, and consistent with the discontinuous variation of Tc(L) with Cr doping. As expected, the substitution of Cr for Mn in this case promotes the FM order, but its effects are significantly different for the two magnetic states. Each Cr drives ∼100 neighboring unit cells, for the high-moment state, and ∼60 unit cells, for the low-moment state, into the FM state. Two definite processes can be identified for the melting of the charge-ordered phase. The FM fraction increases rapidly in the initial stage of Cr doping, and then slowly when the FM population exceeds ∼90%. This could be a common feature of the phase-separated system suffering from random-phase fluctuation according to a theoretical analysis. Exactly opposite effects on phase constituent are produced by Cr doping and Bi doping, and 1% Cr are equivalent to ∼4.6% Bi. In contrast, both Cr doping and magnetic field promote the FM order. 1% Cr correspond to a field of ∼4.5 T for the low-moment state and 6 T for the high-moment state, reducing the energy difference between the charge ordering and the FM states by ∼0.96 meV/Mn and ∼1.3 meV/Mn, respectively.published_or_final_versio

Quantitatively probing two-electron entanglement with a spintronic quantum eraser

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Magnetocaloric effect in itinerant electron metamagnetic systems La(Fe1-xCox)11.9Si1.1

The NaZn13-type compounds La(Fe1–xCox)11.9Si1.1 (x=0.04, 0.06, 0.08) were successfully synthesized, in which the Si content is the limit that can be reached by arc-melting technique. TC is tunable from 243 to 301 K with Co doping from x=0.04 to 0.08. Great magnetic entropy change S in a wide temperature range from ~230 to ~320 K has been observed. The adiabatic temperature change Tad upon changing magnetic field was also directly measured. Tad of sample x=0.06 reaches ~2.4 K upon a field change from 0 to 1.1 T. The temperature hysteresis upon phase transition is small, ~1 K, for all samples. The influence of Co doping on itinerant electron metamagnetic transition and magnetic entropy change is discussed. ©2005 American Institute of Physics.published_or_final_versio

Magnetoresistance in LaFe11.2Co0.7Si1.1 compound

Magnetoresistance has been studied in LaFe/sub 11.2/Co/sub 0.7/Si/sub 1.1/ compound. The ferromagnetic ordering at Curie temperature T/sub C/ of 274 K was found being accompanied by a drastic negative lattice expansion due to the strong structural and magnetic interplay. Such a simultaneous magnetic and lattice change would cause changes in transport properties. The measured transport properties indicate that the transition can be induced by temperature or applied magnetic field. The sample shows a metallic character below T/sub C/, whereas the electrical resistance decreases dramatically and then recovers the metal-like behavior above T/sub C/. Application of a magnetic field retains the transitions via increasing the ferromagnetic ordering temperature. An isothermal increase of field leads to an increase of resistance at temperatures near but above T/sub C/, which is a result of the field-induced metamagnetic transition from paramagnetic to ferromagnetic state.published_or_final_versio

Salivary androgens in adolescence and their value as a marker of puberty: results from the SCAMP cohort

Context: Salivary androgens represent non-invasive biomarkers of puberty that may have utility in clinical and population studies. Objective: To understand normal age-related variation in salivary sex steroids and demonstrate their correlation to pubertal development in young adolescents. Design, Setting, and participants: School-based cohort study of 1,495 adolescents at two time points for collecting saliva samples approximately two years apart. Outcome measures: The saliva samples were analyzed for five androgens (testosterone, androstenedione (A4), 17-hydroxyprogesterone (17-OHP), 11-ketotestosterone (11-KT) and 11β-hydroxyandrostenedione (11-OHA4)) using LC-MS/MS; in addition, salivary dehydroepiandrosterone (DHEA) and oestradiol (OE2) were analyzed by ELISA. Pubertal staging was self-reported using the pubertal development scale (PDS). Results: In 1,236 saliva samples from 903 boys aged between 11-16 years, salivary androgens except DHEA exhibited an increasing trend with an advancing age (ANOVA, p<0.001), with salivary testosterone and A4 concentration showing the strongest correlation (r=0.55, p<0.001 and r=0.48, p<0.001, respectively). In a subgroup analysis of 155 and 63 saliva samples in boys and girls, respectively morning salivary testosterone concentrations showed the highest correlation with composite PDS scores and voice-breaking category from PDS self-report in boys (r=0.75, r=0.67, respectively). In girls, salivary DHEA and OE2 had negligible correlations with age or composite PDS scores. Conclusion: In boys aged 11-16 years, increase in salivary testosterone and A4 is associated with self-reported pubertal progress and represent valid non-invasive biomarkers of puberty in boys

Impact of Microvascular Invasion on Clinical Outcomes After Curative-Intent Resection for Intrahepatic Cholangiocarcinoma

Background: Microvascular invasion (MiVI) is a histological feature of intrahepatic cholangiocarcinoma (ICC) that may be associated with biological behavior. We sought to investigate the impact of MiVI on long-term survival of patients undergoing curative-intent resection for ICC. Methods: A total of 1089 patients undergoing curative-intent resection for ICC were identified. Data on clinicopathological characteristics, disease-free survival (DFS), and overall survival (OS) were compared among patients with no vascular invasion (NoVI), MiVI, and macrovascular invasion (MaVI). Results: A total of 249 (22.9%) patients had MiVI, while 149 (13.7%) patients had MaVI (±MiVI). MiVI was associated with higher incidence of perineural, biliary and adjacent organ invasion, and satellite lesions (all P 18 months) prognosis. Conclusions: Roughly 1 out of 5 patients with resected ICC had MiVI. MiVI was associated with advanced tumor characteristics and a higher risk of tumor recurrence.info:eu-repo/semantics/publishedVersio

The stellar and sub-stellar IMF of simple and composite populations

The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing metallicity and in increasingly massive early-type galaxies. It declines quite steeply below about 0.07Msun with brown dwarfs (BDs) and very low mass stars having their own IMF. The most massive star of mass mmax formed in an embedded cluster with stellar mass Mecl correlates strongly with Mecl being a result of gravitation-driven but resource-limited growth and fragmentation induced starvation. There is no convincing evidence whatsoever that massive stars do form in isolation. Various methods of discretising a stellar population are introduced: optimal sampling leads to a mass distribution that perfectly represents the exact form of the desired IMF and the mmax-to-Mecl relation, while random sampling results in statistical variations of the shape of the IMF. The observed mmax-to-Mecl correlation and the small spread of IMF power-law indices together suggest that optimally sampling the IMF may be the more realistic description of star formation than random sampling from a universal IMF with a constant upper mass limit. Composite populations on galaxy scales, which are formed from many pc scale star formation events, need to be described by the integrated galactic IMF. This IGIMF varies systematically from top-light to top-heavy in dependence of galaxy type and star formation rate, with dramatic implications for theories of galaxy formation and evolution.Comment: 167 pages, 37 figures, 3 tables, published in Stellar Systems and Galactic Structure, Vol.5, Springer. This revised version is consistent with the published version and includes additional references and minor additions to the text as well as a recomputed Table 1. ISBN 978-90-481-8817-

Impact of Body Mass Index on Tumor Recurrence Among Patients Undergoing Curative - Intent Resection of Intrahepatic Cholangiocarcinoma - a Multi-institutional International Analysis

Background: The association between body mass index (BMI) and long-term outcomes of patients with ICC has not been well defined. We sought to define the presentation and oncologic outcomes of patients with ICC undergoing curative-intent resection, according to their BMI category. Methods: Patients who underwent resection of ICC were identified in a multi-institutional database. Patients were categorized as normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25.0-29.9 kg/m2) and obese (BMI≥30 kg/m2) according to the World Health Organization (WHO) definition. Impact of clinico-pathological factors on recurrence-free survival (RFS) was assessed using Cox proportional hazards model among patients in the three BMI categories. Results: Among a total of 790 patients undergoing curative-intent resection of ICC in the analytic cohort, 399 (50.5%) had normal weight, 274 (34.7%) were overweight and 117 (14.8%) were obese. Caucasian patients were more likely to be obese (66.7%, n = 78) and overweight (47.1%, n = 129) compared with Asian (obese: 18.8%, n = 22; overweight: 46%, n = 126) and other races (obese: 14.5%, n = 17; overweight: 6.9%, n = 19)(p 0.05). On multivariable analysis, increased BMI was an independent risk factor for tumor recurrence (OR 1.16, 95% CI 1.02-1.32, for every 5 unit increase). Conclusion: Increasing BMI was associated with incremental increases in the risk of recurrence following curative-intent resection of ICC. Future studies should aim to achieve a better understanding of BMI-related factors relative to prognosis of patients with ICC.info:eu-repo/semantics/publishedVersio