Photon polarization as a probe for quark–gluon plasma dynamics

Prospects of measuring polarized photons emitted from a quark–gluon plasma (QGP) are discussed. In particular, the detection of a possible quark spin polarization in a QGP using circularly polarized photons emitted from the plasma is studied. Photons leave the QGP without further interaction and thus provide a primary probe for quark polarization within the QGP. We find that photon polarization cannot solely arise due to a possible QGP momentum space anisotropy, but may be enhanced due to it. In particular, for oblate momentum distributions and high photon energies, quark polarization is efficiently transfered to photon polarization. The role of competing sources of polarized photons in heavy-ion collisions is discussed.     

Spectrofluorimetric quantification of bilirubin using yttrium–norfloxacin complex as a fluorescence probe in serum samples

A simple and sensitive spectrofluorimetric method was developed to determine trace amounts of bilirubin (BR) using yttrium (Y³⁺)–norfloxacin (NFLX) complex as a fluorescence (FL) probe. NFLX can form a stable binary complex with Y³⁺ and markedly enhances the weak FL signal of the NFLX. The FL intensity of the Y³⁺–NFLX complex decreased significantly in the presence of BR in a buffer solution at pH=7.2. Under optimal conditions, the FL intensity decreased according to the BR concentration and showed a good linear relationship in the range of 0.03–2.3 μg mL^?1 of BR with a correlation coefficient of 0.9988. The limit of detection for the determination of BR was 2.8 ng mL^?1 with a relative standard deviation (RSD) of 1.55% for five replicate determination of 0.05 μg mL^-1 BR. The presented method offers higher sensitivity with simple instrumentation and was applied successfully in detecting BR at low concentrations.     

Preparation and characterization of a novel spherical cellulose–copper(II) oxide composite particles: as a heterogeneous catalyst for the click reaction

Molecular Diversity - In this research, the cellulose–copper(II) oxide composite particles were provided by a novel and simple approach using Schweizer’s reagent via dialysis method at...     

Ultrathin amorphous Ti–Al film used as a diffusion barrier for copper metallization

The viability of ultrathin amorphous Ti–Al film (～4 nm) as a diffusion barrier layer between Cu and Si for the application in Si-based ultra-large scale integration (ULSI) has been investigated. The Cu/Ti–Al/Si heterostructures are annealed in a high vacuum at various temperatures. There is no impurity peaks in the X-ray diffraction patterns for the samples up to annealing temperature of 800 ^°C, although the island-like grains were observed on the surface of the 800 ^°C annealed sample due to dewetting and agglomeration of the Cu film. No inter-reactions can be found from the images of transmission electron microscopy and Ti–Al is still amorphous after high-temperature annealing. These results indicate that Ti–Al film can effectively separate Cu from Si at high temperatures, and that the amorphous ultrathin Ti–Al film can be a very good barrier layer for Cu metallization.     

A Batch Chemiluminescence Determination of Enoxacin Using a Tris-(1,10-phenanthroline)ruthenium(II)–Cerium(IV) System

A batch type chemiluminescence (CL) determination of enoxacin is described. In this work, it was observed that enoxacin could enhance the chemiluminescence (CL) emission Ru(phen)₃ ²⁺–Ce(IV) system and this enhancement effect was dependent on the concentration of enoxacin, based on which, CL system was established for the determination of enoxacin. Under the optimum experimental conditions, the linear range and detection limit are 0.6406–64.06 μg/ml and 0.0210 μg/ml, respectively. The R.S.D. is 1.75%. (n=10). The proposed method has been applied to detect the content of enoxacin in pharmaceutical formulation and human serum with satisfactory results. The possible mechanism of the CL reaction was discussed.     

Neutron–proton elliptic flow difference as a probe for the high density dependence of the symmetry energy

We employ an isospin dependent version of the QMD transport model to study the influence of the isospin dependent part of the nuclear matter equation of state and in-medium nucleon–nucleon cross-sections on the dynamics of heavy-ion collisions at intermediate energies. We find that the extraction of useful information on the isospin-dependent part of the equation of state of nuclear matter from proton or neutron elliptic flows is obstructed by their sensitivity to model parameters and in-medium values of nucleon–nucleon cross-sections. Opposite to that, neutron–proton elliptic flow difference shows little dependence on those variables while its dependence on the isospin asymmetric EoS is enhanced, making it more suitable for a model independent constraining of the high-density behaviour of asy-EoS. Comparison with existing experimental FOPI-LAND neutron–hydrogen data can be used to set an upper limit to the softness of asy-EoS. Successful constraining of the asy-EoS via neutron–proton elliptic flow difference will require experimental data of higher accuracy than presently available.     

Using a portable total reflection X-ray fluorescence system for a multielement analysis of Swiss mice brains with experimental Alzheimer's disease induced by β-amyloid oligomers

Alzheimer's disease (AD) is a progressive and irreversible disorder whose pathological features include β-amyloid (Aβ) plaques and neuronal and synaptic loss. Metals such as iron, copper, and zinc are increased in the brains of patients with AD. Those metals can interact with Aβ, resulting in the promotion of Aβ deposition and formation of plaque. However, no study analyzing the effects of single injection of Aβ soluble oligomers (AβOs) in the elements' homeostasis in mice was developed. Total reflection X-ray fluorescence (TXRF) is a multielement analytical technique that can be utilized to identify and quantify trace elements present in a sample at very low concentrations. In this study, in order to evaluate the concentration of metals in brain regions of Swiss mice, three groups of female mice and three of male mice were studied: control, AD10, and AD100. The AD groups received an AβOs intracerebroventricular injection so as to induce experimental AD. Afterwards, a craniotomy was performed, and six brain compartments were dissected and evaluated. TXRF measurements were performed using a portable TXRF system that uses an X-ray tube with a molybdenum anode and a detector Si-PIN. It is proved to determine the following elements' concentrations: phosphorus, sulfur, potassium, iron, copper, zinc, and rubidium. Results showed differences in the elemental concentration in some brain regions between AD groups. These alterations suggest that AβOs act quickly, even before the amyloid plaques' formation, explaining cognitive deficits independently of amyloid plaques. This study helped to understand that this modification on elemental concentration can be influenced by AβOs.     

Highly selective fluorescent chemosensor for detecting Hg(II) in water based on pyrene functionalized core–shell structured mesoporous silica

Novel pyrene functionalized mesoporous core–shell structured silica (denoted as SiO₂@mSiO₂/Py-Si) was designed and synthesized as a highly selective fluorescent chemosensor for detecting Hg²⁺ in water. The core–shell structured silica was prepared by a simple sol–gel process through coating SiO₂ nanospheres with a layer of ordered mesoporous silica. The surface of outer mesoporous silica shell was then further functionalized by the fluorescent chromophore alkoxysilane modified pyrene (Py-Si). XRD data confirmed that the hexagonal ordered mesoporous structure was preserved after functionalization. The chemosensing material successfully exhibited a remarkable “turn on” response toward Hg²⁺ over miscellaneous metal ions. A good linear response towards Hg²⁺ in the concentration range of 10^?8–10^?4 M was constructed with R²=0.9913. Most importantly, a satisfactory detection limit of 3.4×10^?9 g mL^?1 (down to ppb level) was obtained, which is 100 times lower than our previous report of covalently grafted Py-OH to the bulk mesoporous silica SBA-15. These results indicated that SiO₂@mSiO₂/Py-Si can be used as a highly selective and sensitive fluorescence sensor for Hg²⁺.     

Label-free tungsten disulfide quantum dots as a fluorescent sensing platform for highly efficient detection of copper(Ⅱ) ions

A fluorescent probe for the sensitive and selective determination of copper ion(Cu~(2+)) is presented. It is based on the use of tungsten disulfide quantum dots(WS_2 QDs) which is independent of the p H of solution and emits strong blue fluorescence. Copper ions could cause aggregation of the WS_2 QDs and lead to fluorescence quenching of WS_2 QDs. The change of fluorescence intensity is proportional to the concentration of Cu~(2+), and the limit of detection is 0.4 μM. The fluorescent probe is highly selective for Cu~(2+) over some potentially interfering ions. These results indicate that WS_2 QDs,as a fluorescent sensing platform, can meet the selective requirements for biomedical and environmental application.     

Solid polymer electrolytes in a poly(butadiene-acrylonitrile)–LiBr system

Poly(nitriles) are among the polymer matrices providing high salt solubility and, in some cases, superionic lithium conductivity at ambient temperatures observed in highly concentrated solvent-free polymer electrolytes. However, the properties of these electrolytes in which ionic aggregation prevails remain difficult to reproduce and predict, as current theories do not adequately model their attributes. The development of new concepts for ion transport in highly concentrated solid polymer electrolytes (SPEs) requires a better understanding of the fundamentals of structure formation in a polymer–salt system over a wide concentration range including salt precipitation. In an attempt to approach this goal, a series of fundamental studies was carried out on the systems based on a rubbery random copolymer of butadiene and acrylonitrile (abbreviated as PBAN). In the present work, LiBr with monatomic halide anion was used as a lithium salt. The effect of LiBr concentration (0.05 to 3.35 mol kg^?1) on phase composition, ion–molecular interactions, glass transition temperature, and ionic conductivity was studied by optical microscopy, FTIR, X-ray diffraction, DSC, and impedance measurements. The results were compared with those of PBAN–LiClO₄ and PBAN–LiAsF₆ studied previously. Low salt solubility and separation of a metastable cubic CsCl-type polymorph of LiBr were established. The highest conductivity of ～10^?4 S cm^?1 at >50 °C was observed for heterogeneous samples comprising this phase. While the conductivity of PBAN–LiBr was lower than that of PBAN–LiClO₄ and PBAN–LiAsF₆, this study provides a new insight into the nature of polymer electrolyte systems.     

A synchrotron XPS study of the vanadia–titania system as a model for monolayer oxide catalysts

The deposition of vanadium metal onto stoichiometric TiO₂(110) has been studied with photoelectron spectroscopy from low to high coverages of vanadium. A synchrotron source was employed in XPS experiments for the study of submonolayer coverages of vanadium in order to determine the oxidation state of the vanadia species formed at submonolayer coverages. The exposure of the titania surface to vanadium metal results in charge-transfer from vanadium to titania at the interface. At low doses of the metal vigorous interaction between the metal and titania surface yields reduction of the Ti⁴⁺ species to Ti³⁺ at the interface, as evidenced by both changes in the lineshape of the Ti 2p XPS spectra and Ti LIII-edge spectra. Concurrent with this surface reduction vanadium metal is oxidized. At higher vanadium doses the vanadium 2p binding energy indicates the formation of metallic vanadium. When metallic vanadium deposition is followed by exposure of the surface to oxygen, only one vanadium species remains on the surface, the binding energy of which corresponds to that of the oxide present initially at low doses of vanadium metal. By comparison of the V 2p binding energies to those of bulk oxides, it appears that the oxidation state of the vanadium in the oxide species is +3, suggesting the formation of V₂O₃ on the surface. Vanadium LIII-edge data also suggest that V₂O₅ is not formed by the oxidation of predosed vanadium metal.     

Young's modulus as a function of composition for an n-type lead–antimony–silver–telluride (LAST) thermoelectric material

For 17 cast lead–antimony–silver–telluride (LAST) thermoelectric specimens (representing 14 different chemical compositions), a combination of Vickers and Knoop microindentation techniques were used to determine the composition-dependent Young's modulus, E, which ranged from 24 to 68?GPa. Following microindentation, independent nanoindentation measurements were also performed on 10 of the 17 specimens. In the literature, for pseudobinary joins in ternary or quaternary compounds (with the compositions A _x B_{1– x} C or A _x B_{1– x} CD, respectively), changes in the Young's modulus have been expressed as quadratic functions of the compositional parameter x. In this study, we extend the quadratic functional form to a paraboloid in four composition variables to describe composition-dependent changes in E for the LAST compounds. Also, the composition-dependent changes in LAST are compared to the trends observed in the literature for E and bulk modulus for systems described by a single compositional variable.     

Rhodamine B-based “turn-on” fluorescent and colorimetric chemosensors for highly sensitive and selective detection of mercury (II) ions

Two novel macromolecules based on 2-[3-(2-aminoethylsulfanyl)propylsulfanyl]ethanamine covalently bound to one and two units of rhodamine-B moieties, 1 and 2, were prepared and utilized as fluoroionophores and chromophores for the optical detection of Hg²⁺ ions. The sensors were readily prepared by a conventional two-step synthesis. Especially, sensor 1 exhibits high sensitivity and selective OFF–ON fluorescence enhancement and chromogenic change upon binding to Hg²⁺, which served as a “naked-eye” indicator by a noticeable color change of the solution (from colorless to pink–red color). 1 is shown to discriminate various competing metal ions, particularly Ag⁺ and Cu²⁺, as well as Cd²⁺, Na⁺, Li⁺, K⁺, Ba²⁺, Co²⁺, Ni²⁺, Mg²⁺, Mn²⁺ and Al³⁺, with a detection limit of 10 ppb.     

Using a single donor–acceptor pair attached to a protein molecule as a tool for studying fluctuations in the folding and unfolding of a protein

Using the example of a single protein molecule with two attached dye molecules (a donor–acceptor pair) it it shown how statistical processing of the tracks of donor and acceptor fluorescence can help in investigating the amplitude and rate of the changes in the conformation of a protein molecule.     

Maleic Acid–alt–Styrene Copolymer as Compatibilizer for Poly(Ethylene Oxide)-Poly(Styrene)Blends

Maleic acid-alt-styrene (MAaS) copolymer with number-average molecular weight [Mbar] _n = 2500 was used as a compatibilizer in blends of poly(ethylene oxide) (PEO) and poly(styrene) (PS). PEO with weight-average molecular weight [Mbar] _w = 10⁵ (PEO₁₀₀) and two PS samples with [Mbar] _w = 9 × 10⁴ and 4 × 10⁵, respectively (PS₉₀ and PS₄₀₀, respectively) were used. A depression of the melting temperature T _m of PEO in blends containing MAaS relative to pure PEO and PEO/PS blends was observed. The melting enthalpy ΔH _m for the PEO/PS blends containing MAaS was lower than those of pure PEO and PEO/PS blends without compatibilizer. The crystallization kinetics of PEO and the blends were studied by differential scanning calorimetry (DSC) at different crystallization temperatures T _c. Flory-Huggins interaction parameters χ₁₂ for the blends were estimated. Their values are in good agreement with those obtained for similar systems and suggest that the free energy of mixing ΔG _mix should be negative. Polarized optical microscopy shows differences in the macroscopic homogeneity of the blends containing compatibilizer that could be attributed to a compatibilization process.     

Application of 57Fe Mössbauer spectroscopy as a tool for mining exploration of bornite (Cu5FeS4) copper ore

Nuclear resonance methods, including Mössbauer spectroscopy,are considered as unique techniques suitable for remote on-line mineralogical analysis. The employment of these methods provides potentially significant commercial benefits for mining industry. As applied to copper sulfide ores, Mössbauer spectroscopy method is suitable for the analysis noted. Bornite (formally Cu₅FeS₄) is a significant part of copper ore and identification of its properties is important for economic exploitation of commercial copper ore deposits. A series of natural bornite samples was studied by ⁵⁷Fe Mössbauer spectroscopy. Two aspects were considered: reexamination of ⁵⁷Fe Mössbauer properties of natural bornite samples and their stability irrespective of origin and potential use of miniaturized Mössbauer spectrometers MIMOS II for in-situ bornite identification. The results obtained show a number of potential benefits of introducing the available portative Mössbauer equipment into the mining industry for express mineralogical analysis. In addition, results of some preliminary ^63,65Cu nuclear quadrupole resonance (NQR) studies of bornite are reported and their merits with Mössbauer techniques for bornite detection discussed.     

Anchoring of triethanolamine–Cu(II) complex on magnetic carbon nanotube as a promising recyclable catalyst for the synthesis of 5-substituted 1H-tetrazoles from aldehydes

Molecular Diversity - The development of heterogenization of copper nanoparticles on conductive supports is very challenging and has received much attention. Here, we synthesize a practical,...     

Polythiophene‐functionalized magnetic carbon nanotube-supported copper(I) complex: a novel and retrievable heterogeneous catalyst for the “Phosphine- and Palladium-Free” Suzuki–Miyaura cross-coupling reaction

Molecular Diversity - A simple preparation of catalysts with high catalytic activity and superior cycling stability is very desirable. In this contribution, magnetic carbon nanotube functionalized...