Mn-Doped ZnSe Quantum Dots as Fluorimetric Mercury Sensor

Quantum dots (QDs), because of their exciting optical properties, have been explored as alternative fluorescent sensors to conventional organic fluorophores which are routinely employed for the detection of various analytes via fluorometry. QD probes can detect toxic metal ions, anions, organic molecules with good selectivity and sensitivity. This chapter investigates the synthesis of Mn-doped ZnSe QDs using nucleation-doping strategy. The as-synthesized QDs were characterized by various analytical tools such as ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectroscopy, X-ray diffractometry (XRD) and transmission electron microscopy (TEM). It was found that Mn doping of QDs significantly increases the PL intensity. The PL of the resulting QDs was examined in the presence of different metal ions to check its selective response. Among the various metal ions, Hg2+ exhibits a drastic quenching of the QD’s emission intensity. A Stern-Volmer plot of [Hg2+] sensing using the as-synthesized QDs showed linearity in the range of 0–30 × 10−6 ML−1 with the regression coefficient R2 = 0.99. The detection limit was found to be 6.63 × 10−7 ML−1. Thus, the present Mn-doped ZnSe QDs represent a simple, non-toxic fluorescent probe for the qualitative and quantitative detection of mercury ions in aqueous samples

Link between the diversity, heterogeneity and kinetic properties of amorphous ice structures

Based on neutron wide-angle diffraction and small-angle neutron scattering experiments, we show that there is a correlation between the preparational conditions of amorphous ice structures, their microscopic structural properties, the extent of heterogeneities on a mesoscopic spatial scale and the transformation kinetics. There are only two modifications that can be identified as homogeneous disordered structures, namely the very high-density vHDA and the low-density amorphous LDA ice. Structures showing an intermediate static structure factor with respect to vHDA and LDA are heterogeneous phases. This holds independently from their preparation procedure, i.e. either obtained by pressure amorphisation of ice I_h or by heating of vHDA. The degree of heterogeneity can be progressively suppressed when higher pressures and temperatures are applied for the sample preparation. In accordance with the suppressed heterogeneity the maximum of the static structure factor displays a pronounced narrowing of the first strong peak, shifting towards higher Q-numbers. Moreover, the less heterogeneous the obtained structures are the slower is the transformation kinetics from the high--density modifications into LDA. The well known high-density amorphous structure HDA does not constitute any particular state of the amorphous water network. It is formed due to the preparational procedure working in liquid nitrogen as thermal bath, i.e. at about 77 K

Efficiency gains for thermally coupled solar hydrogen production in extreme cold

Hydrogen produced from water using solar energy constitutes a sustainable alternative to fossil fuels, but solar hydrogen is not yet economically competitive. A major question is whether the approach of coupling photovoltaics via the electricity grid to electrolysis is preferential to higher levels of device integration in artificial leaf designs. Here, we scrutinise the effects of thermally coupled solar water splitting on device efficiencies and catalyst footprint for sub freezing ambient temperatures of amp; 8722;20 C. These conditions are found for a significant fraction of the year in many world regions. Using a combination of electrochemical experiments and modelling, we demonstrate that thermal coupling broadens the operating window and significantly reduces the required catalyst loading when compared to electrolysis decoupled from photovoltaics. Efficiency benefits differ qualitatively for dual and triple junction solar absorbers, which has implications for the general design of outdoor located photoelectochemical devices. Similar to high efficiency photovoltaics that reached technological maturity in space, application cases in polar or alpine climates could support the scale up of solar hydrogen at the global scal

Eroding market stability by proliferation of financial instruments

We contrast Arbitrage Pricing Theory (APT), the theoretical basis for the development of financial instruments, with a dynamical picture of an interacting market, in a simple setting. The proliferation of financial instruments apparently provides more means for risk diversification, making the market more efficient and complete. In the simple market of interacting traders discussed here, the proliferation of financial instruments erodes systemic stability and it drives the market to a critical state characterized by large susceptibility, strong fluctuations and enhanced correlations among risks. This suggests that the hypothesis of APT may not be compatible with a stable market dynamics. In this perspective, market stability acquires the properties of a common good, which suggests that appropriate measures should be introduced in derivative markets, to preserve stability.Comment: 26 pages, 8 figure

Produktivitas Kerja Karyawan Ditinjau Dari Lingkungan Kerja Dan Tingkat Kesejahteraan Pada Pt. Dan Liris Di Sukoharjo Tahun 2016

ABSTRACT Avit May Sofyana. A 210 110 150 EMPLOYEE PRODUCTIVITY BASED ON WELFARE WORK ENVIRONMENT AND LEVEL OF PT. DAN LIRIS IN THE YEAR 2016 SUKOHARJO. Thesis. Accounting Education Studies Program Faculty of Teaching and Education University of Muhammadiyah Surakarta. April, 2016. The purpose of this study was to determine: 1). The influence of the working environment on the productivity of employees at PT. Dan Liris in Sukoharjo 2016. 2). The influence of the level of welfare to work productivity of employees at PT. Dan Liris in Sukoharjo 2016. 3). The influence of the working environment and the welfare of the productivity of employees at PT. Dan Liris in Sukoharjo 2016. This research includes associative quantitative research whose conclusions obtained based on the results of statistical analysis. This study took place PT. Dan Liris. Population 150 employees, 105 employees of samples, sampling using proportionate random sampling technique. Data collection techniques by using documents and questionnaires that have been tested with normality test, reliability test and test multikolinieritas. The analysis technique used is multiple regression. Results of regression analysis regression equation; Y = 17,953+ 0,288X1 + 0,194X2, which means that the productivity of employees affected by the work environment and the level of welfare, based on the analysis and discussion can be concluded that: 1). Work environment positive effect on employee productivity, it is based on the results of multiple linear regression analysis (t test) is known thitung> ttable, namely 4.222> 1.984 and the significance value <0.05, namely 0.000. 2). Well-being is a positive effect on employee productivity, it is based on the results of multiple linear regression analysis (t test) is known thitung> ttable, namely 2.631> 1.984 and the significance value <0.05, ie 0,010. 3). The working environment and welfare together a positive effect on employee productivity, it is based on the results of multiple linear regression analysis (F test) is known Fhitung> Ftable is 17.270> 3.07 with a significance value <0.05 is 0.000. Work environment variables contribute effectively 17.0%. Variable levels of well-being contribute effectively 8.3%. So that the total contribution of both of 25.3% while 74.7% are influenced by other variables not examined by researcher. Keywords: productivity of employees, work environment, welfar

Atomic scale analysis of the GaP Si 100 heterointerface by in situ reflection anisotropy spectroscopy and ab initio density functional theory

A microscopic understanding of the formation of polar on nonpolar interfaces is a prerequisite for well defined heteroepitaxial preparation of III V compounds on 100 silicon for next generation high performance devices. Energetically and kinetically driven Si 100 step formations result in majority domains of monohydride terminated Si dimers oriented either parallel or perpendicular to the step edges. Here, the intentional variation of the Si 100 surface reconstruction controls the sublattice orientation of the heteroepitaxial GaP film, as observed by in situ reflection anisotropy spectroscopy RAS in chemical vapor ambient and confirmed by benchmarking to surface science analytics in ultrahigh vacuum. Ab initio density functional calculations of both abrupt and compensated interfaces are carried out. For P rich chemical potentials at abrupt interfaces, Si P bonds are energetically favored over Si Ga bonds, in agreement with in situ RAS experiments. The energetically most favorable interface is compensated with an intermixed interfacial layer. In situ RAS reveals that the GaP sublattice orientation depends on the P chemical potential during nucleation, which agrees with a kinetically limited formation of abrupt interface