Sponge-like TiO2 layers for dye-sensitized solar cells

A titanium oxide layer used in a dye-sensitized solar cell (DSSC) has to meet two opponent properties to enable high conversion efficiency: a large surface area (for high dye loading) and good connection between TiO₂ grains (for efficient extraction of electrons toward the front contact). In order to meet a trade-off between these criteria a preparation method for TiO₂ paste formulation based on Pechini sol–gel method and commercial nanocrystalline TiO₂ powder has been developed. A series of TiO₂ pastes with different molar ratios between titanium isopropoxide, citric acid and ethylene glycol (1:X:4X) in the paste have been examined. The structure and morphology as well as cross-cut tests of deposited and sintered TiO₂ layers have been analyzed. Results reveal that the paste with X = 8 exhibits the best properties, resulting in an overall conversion efficiency of DSSC under standard test conditions (100 mW/cm², 25 °C, AM 1.5G) up to 6.6% for ionic liquid based electrolyte.     

94Mo高自旋态能级纲图

通过重离子融合蒸发反应^16O(^82Se 4n)^94Mo布局了^94Mo核的高自旋态．利用多探头探测器阵列GASP进行了在束γ测量，从而重新研究了^94Mo核的高自旋态能级结构．基于新发现的一些重要的连接跃迁，对^94Mo核的高自旋态能级纲图做了重要修改．将新的能级结构与壳模型计算进行了比较和讨论．结果表明要正确的描述^94Mo核的高自旋态(自旋值大于14)能级结构，应考虑价中子在d5／2，g7／2和h11/2轨道上的激发．     

Lanthanide(III) chelates as MRI contrast agents: A brief description

Magnetic resonance imaging (MRI) has become a prominent imaging technique in medicine. Gadoliniumbased contrast agents are extensively used to enhance the contrast between normal and diseased tissues through MRI scans. The article illustrates the paramount significance of such contrast agents in MRI applications. Clinically approved contrast agents as well as those in trial period are discussed. Important parameters, i.e. hydration number, rotational correlation time, and mean residence lifetime, influencing the relaxivity (sensitivity) of such agents are described in detail. Various approaches towards relaxivity enhancement are discussed with appropriate examples from the recent literature. A decrease in the Gdwater proton distance results in significant relaxivity enhancement. A comprehensive classification and explanation of Gd³⁺-based contrast agents are presented. Each class is explained with suitable examples. The stability of contrast agents is dependent on their chemical structure. Future contrast agents need to be tissue specific of high relaxivity, low toxicity, and lower administered dose for in vivo use.     

Rational Design of Ag/TiO2 Nanosystems by a Combined RF‐Sputtering/Sol‐Gel Approach

The present work is devoted to the preparation of Ag/TiO₂ nanosystems by an original synthetic strategy, based on the radio‐frequency (RF) sputtering of silver particles on titania‐based xerogels prepared by the sol–gel (SG) route. This approach takes advantage of the synergy between the microporous xerogel structure and the infiltration power characterizing RF‐sputtering, whose combination enables the obtainment of a tailored dispersion of Ag‐containing particles into the titania matrix. In addition, the system′s chemico‐physical features can be tuned further through proper ex situ thermal treatments in air at 400 and 600 °C. The synthesized composites are extensively characterized by the joint use of complementary techniques, that is, X‐ray photoelectron and X‐ray excited Auger electron spectroscopies (XPS, XE‐AES), secondary ion mass spectrometry (SIMS), glancing incidence X‐ray diffraction (GIXRD), field emission scanning electron microscopy (FE–SEM), transmission electron microscopy (TEM), electron diffraction (ED), high‐angle annular dark field scanning TEM (HAADF–STEM), energy‐filtered TEM (EF–TEM) and optical absorption spectroscopy. Finally, the photocatalytic performances of selected samples in the decomposition of the azo‐dye Plasmocorinth B are preliminarily investigated. The obtained results highlight the possibility of tailoring the system characteristics over a broad range, directly influencing their eventual functional properties.     

Estimation of possible airborne elemental inputs to the Slovenian marine environment

In evaluation of the influence of environmental pollution on the ecosystem, data about the elemental concentrations of the atmospheric aerosols, combined with information about particle size and meteorological data, are of significant importance. They are also necessary prerequisites for source/receptor studies and long-range transport modeling. As such, these data are irreplaceable for the estimation of potential elemental input from air to the sea, an understanding of which is one of the tasks of the Mediterranean Pollution Programme (MED POL). Three sampling locations (Sečovlje, Koper, and Iskrba) in Slovenia were chosen for the present study, two at the coast and the third one in a scarcely inhabited, almost unpolluted area, as a reference point, and the element concentrations in the collected particulate matter (PM) were determined. From the Iskrba data the wet scavenging coefficient of airborne sulphur due to precipitation was estimated as k = (1.0±0.3)·10⁻⁴s⁻¹ (at 1.5 mm·h⁻¹).     

Reaction of <Emphasis Type="Italic">N,N</Emphasis>′-bis(trimethylsilyl)dicyandiamide with bis(η<Superscript>5</Superscript>-cyclopentadienylvanadium) dichloride

1,3,5-Tris[bis(η⁵-cyclopentadienyl)chlorovanadium]melamin is prepared in high yield by the reaction of N,N′-bis(trimethylsilyl)dicyandiamide with bis(η⁵-cyclopentadienylvanadium) dichloride in tetrahydrofuran. As side products, trimethylchlorosilane and cyclopentadiene formed. Reaction of N,N′-bis(trimethylsilyl) dicyandiamide with benzoyl chloride results in the formation of tris(benzoyl)melamin.     

Phenolic Glycosides from the Chinese Liverwort Reboulia hemisphaerica

Four new phenolic glycosides, named rebouosides A–D ( 1 – 4 , resp.), along with three known ones 2‐(3,4‐dihydroxyphenyl)ethyl 2‐O‐α‐L ‐rhamnopyranosyl‐β‐D ‐allopyranoside ( 5 ), 2‐(3,4‐dihydroxyphenyl)ethyl β‐D ‐allopyranoside ( 6 ), 2‐(3,4‐dihydroxyphenyl)ethyl β‐D ‐glucopyranoside ( 7 ), and a nucleoside, inosine ( 8 ), were isolated from Chinese liverwort Reboulia hemisphaerica. Their structures were elucidated by acidic hydrolysis and extensive spectroscopic methods, including 2D‐NMR techniques.     

Enhanced quadrupole collectivity at N = 40: the case of neutron-rich Fe isotopes

The transition rates for the 2(1)+ states in (62,64,66)Fe were studied using the recoil distance Doppler-shift technique applied to projectile Coulomb excitation reactions. The deduced E2 strengths illustrate the enhanced collectivity of the neutron-rich Fe isotopes up to N = 40. The results are interpreted using the generalized concept of valence proton symmetry which describes the evolution of nuclear structure around N = 40 as governed by the number of valence protons with respect to Z ≈ 30. The trend of collectivity suggested by the experimental data is described by state-of-the-art shell-model calculations with a new effective interaction developed for the fpgd valence space.     

Sensitivity Advantage of QCL Tunable-Laser Mid-Infrared Spectroscopy Over FTIR Spectroscopy

Abstract

Interest in mid-infrared spectroscopy instrumentation beyond classical FTIR using a thermal light source has increased dramatically in recent years. Synchrotron, supercontinuum, and external-cavity quantum cascade laser light sources are emerging as viable alternatives to the traditional thermal black-body emitter (Globar), especially for remote interrogation of samples (“stand-off” detection) and for hyperspectral imaging at diffraction-limited spatial resolution (“microspectroscopy”). It is thus timely to rigorously consider the relative merits of these different light sources for such applications. We study the theoretical maximum achievable signal-to-noise ratio (SNR) of FTIR using synchrotron or supercontinuum light vs. that of a tunable quantum cascade laser, by reinterpreting an important result that is well known in near-infrared optical coherence tomography imaging. We rigorously show that mid-infrared spectra can be acquired up to 1000 times faster—using the same detected light intensity, the same detector noise level, and without loss of SNR—using the tunable quantum cascade laser as compared with the FTIR approach using synchrotron or supercontinuum light. We experimentally demonstrate the effect using a novel, rapidly tunable quantum cascade laser that acquires spectra at rates of up to 400 per second. We also estimate the maximum potential spectral acquisition rate of our prototype system to be 100,000 per second.