Analysis of size-classified fine and ultrafine particulate matter on substrates with laser-induced breakdown spectroscopy

Airborne particulate matter in the fine (0.1 µm–2.5 µm) and ultrafine (≤ 0.1 µm) size range is supposed to affect human health significantly. Smaller particles intrude more deeply into the lungs, so that an organism directly absorbs toxic compounds. Therefore, knowledge of the size-dependent composition of airborne particles is required to determine their health hazard. In this paper, we demonstrate the application of laser-induced breakdown spectroscopy to directly analyze size-classified particulate matter samples without any sample preparation. Samples analyzed are collected on filter substrates using a cascade impactor. Greased aluminum foils are used as filter substrate. To reduce ablation of the substrate material, low pulse energies of 0.6 mJ are used for plasma excitation. The plasma light is observed using an Echelle spectrometer. The effect of ambient gas and pressure on the line intensities is studied. Calibration samples for 14 elements relevant for human health were produced, and the system was calibrated for concentration ranges up to four orders of magnitude. Finally, the collected samples of particulate originating from steel-making processes were analyzed. The measurements show that the composition of these particles depends strongly on their size. For example, the elements lead, cadmium and copper are enriched within particles of about 200 nm diameter.     

High-Entropy Lithium Argyrodite Solid Electrolytes Enabling Stable All-Solid-State Batteries

Superionic solid electrolytes (SEs) are essential for bulk-type solid-state battery (SSB) applications. Multicomponent SEs are recently attracting attention for their favorable charge-transport properties, however a thorough understanding of how configurational entropy (ΔS_conf) affects ionic conductivity is lacking. Here, we successfully synthesized a series of halogen-rich lithium argyrodites with the general formula Li_5.5PS_4.5Cl_xBr_1.5-x (0≤x≤1.5). Using neutron powder diffraction and ³¹P magic-angle spinning nuclear magnetic resonance spectroscopy, the S²⁻/Cl⁻/Br⁻ occupancy on the anion sublattice was quantitatively analyzed. We show that disorder positively affects Li-ion dynamics, leading to a room-temperature ionic conductivity of 22.7 mS cm⁻¹ (9.6 mS cm⁻¹ in cold-pressed state) for Li_5.5PS_4.5Cl_0.8Br_0.7 (ΔS_conf=1.98R). To the best of our knowledge, this is the first experimental evidence that configurational entropy of the anion sublattice correlates with ion mobility. Our results indicate the possibility of improving ionic conductivity in ceramic ion conductors by tailoring the degree of compositional complexity. Moreover, the Li_5.5PS_4.5Cl_0.8Br_0.7 SE allowed for stable cycling of single-crystal LiNi_0.9Co_0.06Mn_0.04O₂ (s-NCM90) composite cathodes in SSB cells, emphasizing that dual-substituted lithium argyrodites hold great promise in enabling high-performance electrochemical energy storage.     

Electronic structure of CO--an exercise in modern chemical bonding theory

This paper discusses recent progress that has been made in the understanding of the electronic structure and bonding situation of carbon monoxide which was analyzed using modern quantum chemical methods. The new results are compared with standard models of chemical bonding. The electronic charge distribution and the dipole moment, the nature of the HOMO and the bond dissociation energy are discussed in detail.     

Study of latent and etched tracks by a charged particle transmission technique

A recently suggested technique for non-destructive investigation of inhomogeneities in thin objects, which is based on the measurement of the energy spectra of charged particles transmitted through the object, is used for the study of thermal annealing of 10–20 μm thick polyethylene terephtalate, polypropylene and polycarbonate foils irradiated with 1–10 MeV/amu heavy ions. At elevated temperature a foil linear contraction is observed on pristine and irradiated material. Also the foil roughness increases with increasing temperature. On the same foils with etched pores 0.5–1.0 μm in diameter, the thermal annealing results in gradual closing of the pores up to about 30% of their initial diameter at the temperatures of 150–175°C. At higher temperatures the pore diameter increases and achieves its initial value.     

Simultaneously Definitizable and Spectralizable Operators in Krein Space

We study the spectral properties of a self–adjoint operator in Krein space such that one of its natural powers is J–non–negative and some other power is a spectral operator in the Dunford sense.     

The shear modulus of the human vocal fold in a transverse direction

The aim of this study was to measure the shear modulus of the vocal fold in a human hemilarynx, such that the data can be related to direction of applied stress and anatomical context. Dynamic spring rate data were collected using a modified linear skin rheometer using human hemilarynges, and converted to estimated shear modulus via application of a simple shear model. The measurement probe was attached to the epithelial layer of the vocal fold cover using suction. A sinusoidal force of 3g was applied to the epithelium, and the resultant displacement logged at a rate of 1kHz. Force measurement accuracy was 20microg and position measurement accuracy was 4microm. The force was applied in a transverse direction at the midmembranous point between the vocal process and the anterior commissure. The shear modulus of the three female vocal folds ranged from 814 to 1232Pa. The shear modulus of the three male vocal folds ranged from 1021 to 1796Pa. These data demonstrate that it is possible to obtain estimates for the shear modulus of the vocal fold while preserving anatomical context. The modulus values reported here are higher than those reported using parallel plate rheometry. This is to be expected as the tissue is attached to surrounding structures, and is under natural tension.     

Normal mode analyses of methyl palmitate all-trans and disordered forms in wagging progressive region

Normal mode analyses are made for methyl palmitate molecule having all-trans or conformational disorders around the ester head group, in order to explain characteristic observed frequency shifts in the wagging progressive region between all-trans and disorder chains in triglyceride molecules. It was found that one gauche conformation at C(alpha)-C(beta) position and 90 degrees rotation of the ester head group in an alkyl chain produce frequency shifts for twisting mode as observed. For wagging modes, contamination of the disorders around the head group makes assignments change and apparent frequency shifts occur.     

Live Monitoring of Cargo Release From Peptide‐Based Hybrid Nanocapsules Induced by Enzyme Cleavage

The miniemulsion process is used as a new route for the preparation of enzyme‐responsive nanocapsules with payload‐release properties. Peptide‐based hybrid nanocapsules are prepared via interfacial polyaddition containing a water‐soluble dye that is efficiently encapsulated inside. The influence of the synthetic parameters as the functionality of the peptide and the nature of the dispersed phase on the structure of the nanocapsules were investigated. After redispersion in water, the enzymatic cleavage of the peptide sequence and the release of the fluorescent dye are both monitored in real time. This is evidenced because of the quenching FRET system framing the recognition site in the peptide sequence, and the fluorescence recovery of the self‐quenched encapsulated dye respectively.     

Spherically symmetric inhomogeneous dust collapse in higher dimensional space-time and cosmic censorship hypothesis

We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density distribution.