Griffiths-Like Phase in Nanocrystalline Manganite La 0.85 Ca 0.15 MnO 3

The ferromagnetic Curie temperatures TC derived from a temperature derivative of AC susceptibility are equal to 106 K and 161 K for the nanocrystalline and polycrystalline manganites, respectively. The magnetic susceptibility and electron spin resonance confirm that the Griffiths-like phase exists above the Curie temperature in paramagnetic matrix of the nanocrystalline manganite. An analysis of electron spin resonance spectra allows to detect the upper temperature limit for an existence of Griffiths-like phase at temperature TGI = 290 K, which is somewhat higher than the TG of the magnetic susceptibility

Preparation of WS2-PMMA composite films for optical applications

C. B. acknowledges the German research foundation DFG under Emmy-Noether grant BA4856/2-1. C. B., J. Z. and M. C. G. acknowledge the Volkswagen foundation under grant agreement no. 93404-93406. W. J. B. gratefully acknowledges support by a research grant from Science Foundation Ireland (SFI) under Grant Number 12/IA/1306.Thus far, research activities of 2D materials in optics, photonics and optoelectronics predominantly focus on micromechanically cleaved or grown nanosheets. Here, we show that high quality liquid-exfoliated nanosheets offer an alternative approach. Starting from well-defined, monolayer rich WS2 dispersions obtained after liquid exfoliation and size selection in aqueous surfactant, we present an optimised protocol facilitating transfer of the nanosheets to a polymer solution in organic media. From such dispersions, we fabricate WS2–polymer thin films by spin coating. The characteristic photoluminescence of WS2 monolayers is retained in the film at 2.04 eV without broadening (line width 40 meV) or significant changes in the line-shape. This confirms that nanosheet aggregation is efficiently prevented on transfer and deposition. The films are extremely smooth and uniform over large areas with a root mean square roughness <0.5 nm. To demonstrate the potential in optical applications, the nonlinear optical response was studied, revealing promise as optical limiter. In addition, we show that the photoluminescence can be manipulated by coupling the exciton response to cavity photons in a Ag microcavity.PostprintPeer reviewe

Highly conductive and long-term stable films from liquid-phase exfoliated platinum diselenide

Liquid-phase exfoliation (LPE) has been introduced as a versatile and scalable production method for two-dimensional (2D) materials. This method yields dispersions that allow for the fabrication of printable and flexible electronic devices. However, the fabrication of uniform and homogeneous films from LPE dispersions with a performance similar to that of bottom-up grown materials remains a challenge, as the film quality strongly influences the optical and electrical performance of devices. Furthermore, long-term stability remains a major challenge for all 2D material based applications. In this study, we report on highly conductive tiled network films made of platinum diselenide (PtSe2) flakes derived using a scalable LPE method. We characterized the homogeneous films in terms of morphology and electrical behavior. As an example of applicability, we produce a chemiresistive sensor structure with the PtSe2 films and show significant resistance changes upon periodic ammonia gas exposures, revealing a sub-0.1 part per million (ppm) detection limit (DL). More remarkably the devices are fully functional after 15 months, underlining the high stability of PtSe2 based devices

Speciation, Luminescence, and Alkaline Fluorescence Quenching of 4-(2-methylbutyl)aminodipicolinic acid (H2MEBADPA)

4-(2-Methylbutyl)aminodipicolinic acid (H2MEBADPA) has been synthesized and fully characterized in terms of aqueous phase protonation constants (pKa\u27s) and photophysical measurements. The pKa\u27s were determined by spectrophotometric titrations, utilizing a fully sealed titration system. Photophysical measurements consisted of room temperature fluorescence and frozen solution phosphorescence as well as quantum yield determinations at various pH, which showed that only fully deprotonated MEBADPA2– is appreciably emissive. The fluorescence of MEBADPA2– has been determined to be quenched by hydroxide and methoxide anions, most likely through base-catalyzed excited-state tautomerism or proton transfer. This quenching phenomenon has been quantitatively explored through steady-state and time-resolved fluorescence measurements. Utilizing the determined pKas and quenching constants, the fluorescent intensity of MEBADPA2– has been successfully modeled as a function of pH

New Preventive Programs of the Polish Hypertension Society in Gdansk. Part I: SOPKARD

Badania ogólnopolskie przeprowadzone metodą sondażu reprezentatywnego pod koniec 1997 roku wskazały na utrzymywanie się niedostatecznego wykrywania (46%) oraz niewielkiej skuteczności leczenia (8,5%) nadciśnienia tętniczego, a także na pogarszanie się sytuacji, szczególnie w małych miastach i na wsi. Realizując pilną potrzebę wprowadzania kompleksowych działań na rzecz skutecznej prewencji nadciśnienia, Oddział Gdański PTNT opracował i wdrożył, na podstawie sprawdzonych wzorów szwedzkich, tak zwany Program Sopocki (SOPKARD). Program ma charakter usługowy i badawczy. Jego celem jest poprawa wykrywania i skuteczności leczenia nadciśnienia tętniczego, cukrzycy i hipercholesterolemii. Co roku na badania w Sopocie zapraszani są wszyscy mieszkańcy kończący w danym roku kalendarzowym 40 i 50 lat. Projekt realizują pielęgniarki i lekarze podstawowej opieki zdrowotnej we współpracy z Akademią Medyczną w Gdańsku, Pomorską Kasą Chorych i samorządem lokalnym. Program ma charakter pilotowy dla innych miast Pomorza. Działania edukacyjne z wykorzystaniem mediów i akcje pomiarów ciśnienia obejmują wszystkich mieszkańców miasta. Badanie epidemiologiczne przeprowadzone przed rozpoczęciem programu jednoznacznie potwierdziło celowość i potencjalną opłacalność tego typu działań. W Sopocie, w grupie 50-latków połowa pali papierosy, tylko dwie trzecie mieszkańców mierzy sobie ciśnienie, u 45% stwierdzono nadciśnienie tętnicze (kryterium 140/90 mm Hg), tylko 5% spośród osób z nadciśnieniem jest skutecznie leczonych; o cukrzycy wie 4%, podczas gdy u 13% mieszkańców glikemia na czczo wynosi powyżej 126 mg/dl. Zorganizowana we wrześniu bieżącego roku w Sopocie konferencja z udziałem Minister Zdrowia Franciszki Cegielskiej, przedstawicieli Sejmu i Senatu RP, Kas Chorych oraz autorytetów medycznych i dziennikarzy miała na celu zintegrowanie różnych środowisk w celu skutecznej prewencji chorób serca i naczyń w Polsce.Representative survey performed in 1997 in Poland showed still low awareness of hypertension (46%) and poor control ofhigh blood pressure (8.5%), with the worst situation in small towns and villages. To intensify preventive measures we have implemented a new preventive program in Sopot (small town nearby Gdansk) based on models worked out in Sweden. Its aim is to increase detection and control of arterial hypertension, diabetes mellitus and hypercholesterolaemia. It is also a pilot program for other cities in Gdansk region. The program (SOPKARD) is intended to provide service to the community of Sopot, and to yield valid research material. It is based on co-operation between primary health care, university authorities and health insurance companies. Estimated minimum duration is 10 years. SOPKARD is addressed to those Sopot inhabitants who within the period 1999-2009 will reach the age of 40 and 50 years. The representative survey performed to measure the prevalence of cardiovascular risk factors among citizens of Sopot fully confirmed the necessity of such programs. In the group of 50-year-old inhabitants, half of them smoked cigarettes, only two thirds were aware of their blood pressure level, 45% were hypertensives (criterion 140/90 mm Hg). Among hypertensive subjects, only in 5% blood pressure was well controlled. Fasting blood glu- cose > 126 mg/dl was found in 13% of respondents, and only 4% declared to have diabetes. The aim of the conference, which inaugurated the program, was to develop an agreement between medical experts, journalists and representatives from different political groups to improve control ofcardiovascular diseases in our region and in Poland