Current noise through a Kondo quantum dot in a SU(N) Fermi liquid state

The current noise through a mesoscopic quantum dot is calculated and analyzed in the Fermi liquid regime of the SU(N) Kondo model. The results connect the Johnson-Nyquist noise to the shot noise for an arbitrary ratio of voltage and temperature, and show that temperature corrections are sizable in the usual experiments. For the experimentally relevant SU(4) case, quasiparticle interactions are shown to increase the shot noise.     

Crystal structure of the quaternary compound CuTa2InTe4 from X-ray powder diffraction

The crystal structure of the new quaternary compound CuTa₂InTe₄ was studied using X-ray powder diffraction data. The powder pattern refined by the Rietveld method indicates that this material crystallizes in the tetragonal system with space group I-4¯2m (No. 121), Z=2, and unit cell parameters a=6.1963(2) Å, c=12.4164(4) Å, c/a=2.00 and V=476.72(3) Å³. The structural and instrumental refinement of 28 parameters led to R_p=10.4%, R_wp=11.1%, R_exp=6.8% and χ²=2.7 for 96 independent reflections.     

Purification and Applications of a Lectin from the Mushroom Gymnopilus spectabilis

A lectin was isolated from fruiting bodies of the mushroom Gymnopilus spectabilis (GSL) by ionic exchange chromatography. The lectin agglutinates mouse red cells exhibiting broad specificity towards several monosaccharides including the N-acetylneuraminic acid. Agglutination was also inhibited by the glycoproteins: fetuin, lactoferrin, and recombinant erythropoietin. GSL is a glycoprotein possessing 16 % of carbohydrates; the SDS-PAGE showed two bands with molecular mass of 52.1 and 64.4 kDa. Isoelectric focusing displayed microheterogeneity, with two bands at pIs 5.1 and 5.3. The lectin was stable between pH 2 and pH 8 while at pH 10, the agglutination decayed to 50 % of initial activity. Incubation at 40 and 80 °C led to 50 and 100 % loss in activity of the lectin, respectively. Synthesized GSL-Sepharose interacts with serum pregnant mare gonadotropin, and at least two subpopulations of this glycoprotein were separated. There was no interaction between transferrin and soluble GSL while a partial recognition was achieved with GSL-Sepharose. The terminal sialic acid seems to play an active role in modifying the interaction with GSL, depending if the lectin is in a soluble or immobilized form. The purified lectin inhibited in vitro the growth of Staphylococcus aureus and Aspergillus niger.     

Heteroatom Effect on Star‐Shaped Hole‐Transporting Materials for Perovskite Solar Cells

Three new star‐shaped hole‐transporting materials (HTMs) incorporating benzotripyrrole, benzotrifuran, and benzotriselenophene central cores endowed with three‐armed triphenylamine moieties ( BTP‐1 , BTF‐1 , and BTSe‐1 , respectively) are designed, synthesized, and implemented in perovskite solar cells (PSCs). The impact that the heteroatom‐containing central scaffold has on the electrochemical and photophysical properties, as well as on the photovoltaic performance, is systematically investigated and compared with their sulfur‐rich analogue ( BTT‐3 ). The new HTMs exhibit suitable highest‐occupied molecular orbitals (HOMO) levels regarding the valence band of the perovskite, which ensure efficient hole extraction at the perovskite/HTM interface. The molecular structures of BTF‐1 , BTT‐3 , and BTSe‐1 are fully elucidated by single‐crystal X‐ray crystallography as toluene solvates. The optimized (FAPbI₃)_0.85(MAPbBr₃)_0.15‐based perovskite solar cells employing the tailor‐made, chalcogenide‐based HTMs exhibit remarkable power conversion efficiencies up to 18.5%, which are comparable to the devices based on the benchmark spiro‐OMeTAD. PSCs with BTP‐1 exhibit a more limited power conversion efficiency of 15.5%, with noticeable hysteresis. This systematic study indicates that chalcogenide‐based derivatives are promising HTM candidates to compete efficiently with spiro‐OMeTAD.     

Correlation between surface tension and void fraction in ionic liquids

An effort to systematize published and new data on the surface tension gamma of ionic liquids (ILs) is based on the hypothesis that the dimensionless surface tension parameter gamma V v (2/3)/ kT is a function of the void fraction x v = V v/ V m. The void volume V v is defined as the difference between the liquid volume V m occupied by an ion pair (known from cationic and anionic masses and liquid density measurements) and the sum V (+) + V (-) of the cationic and anionic volumes (known from crystal structures), while kT is the thermal energy. Our hypothesis that gamma V m (2/3)/ kT = G( x v) is initially based on cavity theory. It is then refined based on periodic lattice modeling, which reveals that the number N of voids per unit cell (hence the dimensionless surface tension) must depend on x v. Testing our hypothesis against data for the five ILs for which surface tension and density data are available over a wide range of temperatures collapses all of these data almost on a single curve G( x v), provided that slight (4%) self-consistent modifications are introduced on published crystallographic data for V (+) and V (-). An attempt to correlate the surface tension vs temperature data available for inorganic molten salts is similarly successful, but at the expense of larger shifts on the published ionic radii (8.8% for K; 3.3% for I). The collapsed G( x v) curves for ILs and inorganic salts do not overlap anywhere on x v space, and appear to be different from each other. The existence of a relation between gamma and x v is rationalized with a simple capillary model minimizing the energy. Our success in correlating surface tension to void fraction may apply also to other liquid properties.     

Synthesis of hydroxycinnamic acid glucuronides and investigation of their affinity for human serum albumin

Hydroxycinnamic acids (HCAs) are among the most abundant dietary polyphenols. Recent bioavailability studies have shown that HCAs enter the blood circulation mainly as glucuronides, which are thus most likely to express their potential health effects. In this work, an efficient synthesis of HCA O-arylglucuronides is developed. As for many xenobiotics, the resilience of HCA O-arylglucuronides in plasma and subsequent delivery to tissues could be governed by their binding to human serum albumin (HSA). Hence, the affinity of HCA O-arylglucuronides for HSA and its possible binding site were investigated by fluorescence spectroscopy. HCA O-arylglucuronides turn out to be moderate HSA ligands (K in the range 1-4 x 10(4) M(-1)) that bind HSA in sub-domain IIA, competitively or noncompetitively with other sub-domain IIA ligands such as dansylamide and the flavonol quercetin.     

Carbon-related matrix effects in inductively coupled plasma atomic emission spectrometry

In Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), it has been observed that the emission intensity of some atomic lines is enhanced or depressed by the presence of carbon in the matrix. The goal of this work was to investigate the origin and magnitude of the carbon-related matrix effects in ICP-AES. To this end, the influence of the carbon concentration and source (i.e. glycerol, citric acid and potassium hydrogen phthalate), the experimental conditions and sample introduction system on the aerosol characteristics and transport, plasma excitation conditions and the emission intensity of several atomic and ionic lines of a total of 15 elements has been studied. Results indicate that carbon related matrix effects do not depend on the carbon source and they become more severe when the amount of carbon loaded into the plasma increases, i.e., when using: (i) carbon concentrations higher than 5 g L^− 1; (ii) high sample uptake rates; and (iii) efficient sample introduction systems. Thus, when introducing carbon into the plasma, the emission intensity of atomic lines with excitation energies below 6 eV is depressed (up to 15%) whereas the emission intensity of atomic lines of higher excitation energies (i.e. As and Se) are enhanced (up to 30%). The emission intensity of the ionic lines is not affected by the presence of carbon. The origin of the carbon-related interferences on the emission intensity of atomic lines is related to changes in the line excitation mechanism since the carbon containing solutions show the same aerosol characteristics and transport efficiencies as the corresponding aqueous solutions. Based on the previous findings, a calibration approach for the accurate determination of Se in a Se-enriched yeast certified material (SELM-1) has been proposed.     

Low-temperature single-wall carbon nanotubes synthesis: feedstock decomposition limited growth

We report on the lowest temperature of SWCNT growth using endothermic decomposition of CH4 gas on a specially activated alumina-supported Fe:Mo catalyst. However, the observed lowest growth temperature (560 degrees C) is higher than that reported previously for exothermic feedstock type. Our observation indicates that the decomposition threshold temperature of the feedstock limits the SWCNT growth. This study also suggests that, by using more active carbon feedstock or somehow facilitating its decomposition, one could enable the synthesis of SWCNT at an even lower temperature.