Analisis Portofolio Optimal Dengan Single Index Model Untuk Meminimumkan Risiko Bagi Investor Di Bursa Efek Indonesia (Studi Pada Saham Indeks Kompas 100 Periode Februari 2010-juli 2014)

Investments can be made in the capital market, capital market instruments which are mostly attractive for investors is stock. Stock provides a return in the form of capital gains and dividends yield, not only noticing the return, investors need to pay attention to the investments risk. Unsystematis risk can be minimized by forming the optimal portfolio using one of the methods that is single index model. Study purpose is to knowing the stocks forming the optimal portfolio, the proportion of funds allocated to each stocks, the level of expectation return and risk.The method used in this research is descriptive research method with a quantitative approach. The samples used were 46 stocks in Kompas 100 Index, which meets the criteria for sampling. The results showed that 12 stocks of forming optimal portfolio, the stocks of which are UNVR, TRAM, MNCN, BHIT, JSMR, BMTR, GJTL, KLBF, AALI, CPIN, AKRA, and ASRI. Stock with highest proportion of funds is TRAM (23,52%), stock with lowest proportion of funds is AALI (0,62%). Portfolio which are formed will give return expectations by 3,05477% and carry the risk for about 0,1228%

Theoretical Prediction of Phonon-Mediated Superconductivity in 2D ZrB_<i>x</i> (<i>x</i> = 4 and 6) Monolayers

Two-dimensional (2D) superconductors have been studied extensively because of their potential applications in nanosuperconducting devices. Based on the crystal structure prediction method, we identified an energetically and dynamically stable monolayer structure for 2D ZrB6. Through first-principles calculations and comparison with the 2D ZrB4 monolayer, we discovered that both are intrinsic phonon-mediated superconductors, and ZrB6 has a higher superconducting transition temperature of 15.79 K, while ZrB4 has only 1.98 K. Further investigation revealed that the discrepancy is due to the varied coordinating environment. The structure of the pure plane formed by the larger coordination number inhibits the in-plane vibration of the Zr and B atoms in the ZrB4 monolayer. These findings will aid in the design and research of 2D high-temperature superconductors

Table1_Effects of Several Organic Fertilizers on Heavy Metal Passivation in Cd-Contaminated Gray-Purple Soil.DOCX

Soil heavy metal pollution has become a major ecological and environmental problem and a serious threat to global food security. Organic fertilizer can not only improve soil quality and provide nutrients for plants but also reduce the harm of heavy metal ions to a certain extent, meaning it has become a current research hotspot in the field of heavy metal passivation. In this paper, a completely combined experimental design was used to compare the effects of five organic fertilizers [nutshell organic fertilizer (NOF), pig manure organic fertilizer (PMOF), sludge organic fertilizer (SOF), humus soil organic fertilizer (HSOF) and earthworm soil organic fertilizer (ESOF)] on available Cd in soil with different pollution levels at different dosages, and the passivation mechanism of soil Cd was preliminarily discussed. The results showed that all kinds of organic fertilizers were passivated by reducing the Cd availability, and their effects on the Cd availability of purple soil were closely related to the degree of soil pollution and the amount of organic fertilizers. The passivation effect of moderate Cd-contaminated soil was the best, which increased with the increase of organic fertilizer application rate, and the effects of NOF and SOF were the best. However, the passivation effect of organic fertilizers on soil Cd was the worst in mild Cd-contaminated soil, especially ESOF. The results of Cd morphological correlation analysis showed that Exe-Cd and FeMnOx-Cd in the soil had significantly positive contributions to available Cd, while Res-Cd showed significantly negative contributions. And in moderate Cd contaminated soil, Exe-Cd content decreased by 7.12%–28.50%, while Res-Cd content increased by 19.74%–65.81%. In addition, the content of available Cd in soil decreased first and then increased with time after adding organic fertilizer, and reached the lowest value at 15 days and stabilized after 60 days. The conclusion of this paper can provide a theoretical basis for the rational use of organic fertilizer to reduce the bioavailability of cadmium in Gray-Purple soil.</p

Table2_Effects of Several Organic Fertilizers on Heavy Metal Passivation in Cd-Contaminated Gray-Purple Soil.XLSX

Soil heavy metal pollution has become a major ecological and environmental problem and a serious threat to global food security. Organic fertilizer can not only improve soil quality and provide nutrients for plants but also reduce the harm of heavy metal ions to a certain extent, meaning it has become a current research hotspot in the field of heavy metal passivation. In this paper, a completely combined experimental design was used to compare the effects of five organic fertilizers [nutshell organic fertilizer (NOF), pig manure organic fertilizer (PMOF), sludge organic fertilizer (SOF), humus soil organic fertilizer (HSOF) and earthworm soil organic fertilizer (ESOF)] on available Cd in soil with different pollution levels at different dosages, and the passivation mechanism of soil Cd was preliminarily discussed. The results showed that all kinds of organic fertilizers were passivated by reducing the Cd availability, and their effects on the Cd availability of purple soil were closely related to the degree of soil pollution and the amount of organic fertilizers. The passivation effect of moderate Cd-contaminated soil was the best, which increased with the increase of organic fertilizer application rate, and the effects of NOF and SOF were the best. However, the passivation effect of organic fertilizers on soil Cd was the worst in mild Cd-contaminated soil, especially ESOF. The results of Cd morphological correlation analysis showed that Exe-Cd and FeMnOx-Cd in the soil had significantly positive contributions to available Cd, while Res-Cd showed significantly negative contributions. And in moderate Cd contaminated soil, Exe-Cd content decreased by 7.12%–28.50%, while Res-Cd content increased by 19.74%–65.81%. In addition, the content of available Cd in soil decreased first and then increased with time after adding organic fertilizer, and reached the lowest value at 15 days and stabilized after 60 days. The conclusion of this paper can provide a theoretical basis for the rational use of organic fertilizer to reduce the bioavailability of cadmium in Gray-Purple soil.</p

Interfacial Energy Barrier Tuning for Enhanced Thermoelectric Performance of PEDOT Nanowire/SWNT/PEDOT:PSS Ternary Composites

Ternary composites based on single-walled carbon nanotube (SWNT), poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS), and PEDOT nanowire (NW) were prepared by solution mixing methods. Studies show that Seebeck coefficient of the composites with SWNT and PEDOT:PSS could be further enhanced by addition of PEDOT NW to form ternary hybrids, which is attributable to interfacial carrier energy filtering effect which selectively filters the low-energy carriers and overpasses the high-energy carriers at NW/PEDOT:PSS interfaces. The addition of SWNT into the system leads to high electrical conductivity of the resulting ternary composites. The combination of high Seebeck coefficient and high conductivity results in the ternary composite with high power factor (PF), and an optimized PF of ∼352 μW m–1 K–2 at room temperature is obtained. The mechanism behind the enhancement of the Seebeck coefficient is also elucidated by studying the carrier transport phenomena through PEDOT NW/PEDOT:PSS interfaces via tuning of the interfacial energy barriers that resulted from different doping levels of PEDOT NWs. Thermoelectric generators assembled by five optimized composite films exhibit a maximum output power of 414 nW when ΔT = 40 K, which demonstrates the potential capability for practical thermal energy harvesting

Light-shift-free and dead-zone-free atomic orientation based scalar magnetometry using a single amplitude-modulated beam

Detection dead zones and heading errors induced by light shifts are two important problems in optically pumped scalar magnetometry. We introduce an atomic orientation based single-beam magnetometry scheme to simultaneously solve these problems, using a polarization-reversing and path-bending Herriott cavity. Here, a reflection mirror is inserted into the cavity to bend the optical paths in the middle, and divide them into two separated orthogonal regions to avoid the detection dead zone. Moreover, half-wave plates are added in the center of each optical region, so that the light polarization is flipped each time it passes the wave plates and the light shift effects are spatially averaged out. This operation is demonstrated to eliminate the unnoticed heading errors induced by ac light shifts. The methods developed in this paper are robust to use, and easy to be applied in other atomic devices

Synthesis of M@TiO₂ (M = Au, Pd, Pt) Core–Shell Nanocomposites with Tunable Photoreactivity

The core–shell nanocomposites of M@TiO2 (M = Au, Pd, Pt) have been synthesized successfully via a facile hydrothermal treatment of TiF4 precursor and noble metal colloid particles. Their properties were determined by a collection of joint techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction spectra (XRD), ultraviolet/visible diffuse reflectance spectra (DRS), photoluminescence spectra (PL), and electron spin resonance spectra (ESR). Photocatalytic degradation of Rhodamine B (RhB) in the liquid phase served as a probe reaction to evaluate the activity of the as-prepared M@TiO2 (M = Au, Pd, Pt) core–shell nanocomposites under the irradiation of both visible light and ultraviolet (UV) light. The results reveal that these core–shell nanocomposites possess tunable photoreactivity. It is interesting to find that the incorporation of noble metal core into the shell of TiO2 only contributes to enhancement of visible light photocatalytic activity of TiO2. The noble metal cores are believed to play an essential role in affecting the photoreactivity because they are able to trap electrons, improve the electron–hole pairs life, and enhance the visible light absorption intensity that are all beneficial for enhancement of the visible light photocatalytic activity of TiO2. However, the incorporation of noble metal core significantly lowers the UV light absorption intensity, thus leading to the obervation that, under UV light irradiation, the bare TiO2 still exhibits higher activity than M@TiO2 core–shell nanocomposites. The possible radical species involved in the degradation of RhB were analyzed by means of the PL and ESR techniques. Recycled activity tests demonstrate that the incorporation of metal core into the shell of TiO2 will inhibit the photocorrison behavior and provide much better photocatalytic stability of M@TiO2 (M = Au, Pd, Pt) nanocomposites than the bare TiO2. It is hoped that our work could render guided information for steering toward the design and application of TiO2-coated core–shell nanomaterials with tunable photocatalytic activity

A Simple Strategy for Fabrication of “Plum-Pudding” Type Pd@CeO₂ Semiconductor Nanocomposite as a Visible-Light-Driven Photocatalyst for Selective Oxidation

The Pd@CeO₂ semiconductor nanocomposite with “plum-pudding” structure has been fabricated successfully via a facile low-temperature hydrothermal reaction of polyvinylpyrrolidone (PVP)-capped Pd colloidal particles and cerium chloride precursor followed by a calcination process in air. Different characterization techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission scanning electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), UV–vis diffuse reflectance spectra (DRS), X-ray photoelectron spectra (XPS), photoluminescence spectra (PL), nitrogen adsorption–desorption, and electron spin resonance spectra (ESR), have been used to investigate the structure and properties of the Pd@CeO₂ nanocomposite. It is found that the nanosized Pd particles are evenly dispersed into the matrix of CeO₂, thus forming a plum-pudding structure, i.e., multi-Pd core@CeO₂ shell configuration. This unique nanostructure endows the Pd@CeO₂ nanocomposite with enhanced activity and selectivity toward the visible-light-driven oxidation of various benzylic alcohols to corresponding aldehydes using dioxygen as oxidant at room temperature and ambient pressure compared with a supported Pd/CeO₂ nanocomposite and nanosized CeO₂ powder. The formation of the multi-Pd core@CeO₂ shell structure can be understood by a synergistic interaction of heterogeneous seeded growth process, monolayer-capped core coalescence, and shell re-encapsulation. Together with the previous report, it can be concluded that the intrinsic structure nature of noble metal colloids is able to play a key role in affecting the formation process of noble metal core@semiconductor shell nanocomposites, by which we can realize the design and preparation of different specific core–shell nanostructures with atomic scale accuracy. It is hoped that our current work could open promising prospects of the fabrication of multimetal core@semiconductor shell nanocomposites and their application to visible-light-driven selective organic transformations

Regio- and Diastereoselective Construction of Functionalized Benzo[<i>b</i>]oxepines and Benzo[<i>b</i>]azepines via Recyclable Gold(I)-Catalyzed Cyclizations

The heterogeneous gold-catalyzed cyclization of (o-alkynyl)­phenoxy- or N-(o-alkynylphenyl)­tolylsulfonamidoacrylates with alcohols has been developed by using an MCM-41-anchored diphenylphosphine-Au­(I) complex [MCM-41-Ph2P-AuNTf2] as the catalyst under mild reaction conditions, yielding diverse functionalized benzo­[b]­oxepines or benzo­[b]­azepines with good to high yields and excellent diastereoselectivity. This heterogenized gold­(I) catalyst exhibits a comparable activity to homogeneous Ph3PAuNTf2 and can be facilely recovered by a simple filtration of the reaction solution and reused more than seven times with almost a consistent catalytic efficiency

Synthesis of One-Dimensional CdS@TiO₂ Core–Shell Nanocomposites Photocatalyst for Selective Redox: The Dual Role of TiO₂ Shell

One-dimensional (1D) CdS@TiO₂ core–shell nanocomposites (CSNs) have been successfully synthesized via a two-step solvothermal method. The structure and properties of 1D CdS@TiO₂ core–shell nanocomposites (CdS@TiO₂ CSNs) have been characterized by a series of techniques, including X-ray diffraction (XRD), ultraviolet–visible-light (UV-vis) diffuse reflectance spectra (DRS), field-emission scanning electron microscopy (FESEM), photoluminescence spectra (PL), and electron spin resonance (ESR) spectroscopy. The results demonstrate that 1D core–shell structure is formed by coating TiO₂ onto the substrate of CdS nanowires (NWs). The visible-light-driven photocatalytic activities of the as-prepared 1D CdS@TiO₂ CSNs are evaluated by selective oxidation of alcohols to aldehydes under mild conditions. Compared to bare CdS NWs, an obvious enhancement of both conversion and yield is achieved over 1D CdS@TiO₂ CSNs, which is ascribed to the prolonged lifetime of photogenerated charge carriers over 1D CdS@TiO₂ CSNs under visible-light irradiation. Furthermore, it is disclosed that the photogenerated holes from CdS core can be stuck by the TiO₂ shell, as evidenced by controlled radical scavenger experiments and efficiently selective reduction of heavy-metal ions, Cr­(VI), over 1D CdS@TiO₂ CSNs, which consequently leads to the fact that the reaction mechanism of photocatalytic oxidation of alcohols over 1D CdS@TiO₂ CSNs is apparently different from that over 1D CdS NWs under visible-light irradiation. It is hoped that our work could not only offer useful information on the fabrication of various specific 1D core–shell nanostructures, but also open a new doorway of such 1D core–shell semiconductors as visible-light photocatalysts in the promising field of selective transformations