On the effects of mechanical stress of biological membranes in modeling of swelling dynamics of biological systems

We highlight mechanical stretching and bending of membranes and the importance of membrane deformations in the analysis of swelling dynamics of biological systems, including cells and subcellular organelles. Membrane deformation upon swelling generates tensile stress and internal pressure, contributing to volume changes in biological systems. Therefore, in addition to physical (internal/external) and chemical factors, mechanical properties of the membranes should be considered in modeling analysis of cellular swelling. Here we describe an approach that considers mechanical properties of the membranes in the analysis of swelling dynamics of biological systems. This approach includes membrane bending and stretching deformations into the model, producing a more realistic description of swelling. We also discuss the effects of membrane stretching on swelling dynamics. We report that additional pressure generated by membrane bending is negligible, compared to pressures generated by membrane stretching, when both membrane surface area and volume are variable parameters. Note that bending deformations are reversible, while stretching deformation may be irreversible, leading to membrane disruption when they exceed a certain threshold level. Therefore, bending deformations need only be considered in reversible physiological swelling, whereas stretching deformations should also be considered in pathological irreversible swelling. Thus, the currently proposed approach may be used to develop a detailed biophysical model describing the transition from physiological to pathological swelling mode.National Aeronautics & Space Administration (NASA):80NSSC19M0049; PR Space Grant (NASA):NNX15AI11Hinfo:eu-repo/semantics/publishedVersio

Visualization of Nd3+-doped Laf3 Nanoparticles For Near Infrared Bioimaging via Upconversion Luminescence at Multiphoton Excitation Microscopyvisualization of Nd3+-doped Laf3 Nanoparticles For Near Infrared Bioimaging via Upconversion Luminescence at Multiphoton Excitation Microscopy

Recent developments in the field of biophotonics facilitate the raise of interest to inorganic nanoparticles (NPs) doped with Nd 3+ ions, because of their near-infrared (NIR) absorption. These NPs are interesting bioimaging probes for deep tissue visualization, while they can also act as local thermometers in biological tissues. Despite the good possibilities for visualization of NPs with Nd 3+ ions in NIR spectral range, difficulties arise when studying the cellular uptake of these NPs using commercially available fluorescence microscopy systems, since the selection of suitable luminescence detectors is limited. However, Nd 3+ ions are able to convert NIR radiation into visible light, showing upconversion properties. In this paper we found optimal parameters to excite upconversion luminescence of Nd 3+ :LaF 3 NPs in living cells and to compare the distribution of the NPs inside the cell culture of human macrophages THP-1 obtained by two methods. Firstly, by detecting the upconversion luminescence of the NPs in VIS under NIR multiphoton excitation using laser scanning confocal microscopy and secondly, using transmission electron microscopy

A Survey on the Krein-von Neumann Extension, the corresponding Abstract Buckling Problem, and Weyl-Type Spectral Asymptotics for Perturbed Krein Laplacians in Nonsmooth Domains

In the first (and abstract) part of this survey we prove the unitary equivalence of the inverse of the Krein--von Neumann extension (on the orthogonal complement of its kernel) of a densely defined, closed, strictly positive operator, $S\geq \varepsilon I_{\mathcal{H}}$ for some $\varepsilon >0$ in a Hilbert space $\mathcal{H}$ to an abstract buckling problem operator. This establishes the Krein extension as a natural object in elasticity theory (in analogy to the Friedrichs extension, which found natural applications in quantum mechanics, elasticity, etc.). In the second, and principal part of this survey, we study spectral properties for $H_{K,\Omega}$, the Krein--von Neumann extension of the perturbed Laplacian $-\Delta+V$ (in short, the perturbed Krein Laplacian) defined on $C^\infty_0(\Omega)$, where $V$ is measurable, bounded and nonnegative, in a bounded open set $\Omega\subset\mathbb{R}^n$ belonging to a class of nonsmooth domains which contains all convex domains, along with all domains of class $C^{1,r}$, $r>1/2$.Comment: 68 pages. arXiv admin note: extreme text overlap with arXiv:0907.144

Development of 100^{100}Mo-containing scintillating bolometers for a high-sensitivity neutrinoless double-beta decay search

We report recent achievements in the development of scintillating bolometers to search for neutrinoless double-beta decay of $^{100}$Mo. The presented results have been obtained in the framework of the LUMINEU, LUCIFER and EDELWEISS collaborations, and are now part of the R\&D activities towards CUPID (CUORE Update with Particle IDentification), a proposed next-generation double-beta decay experiment based on the CUORE experience. We have developed a technology for the production of large mass ($\sim$1 kg), high optical quality, radiopure zinc and lithium molybdate crystal scintillators (ZnMoO$_4$ and Li$_2$MoO$_4$, respectively) from deeply purified natural and $^{100}$Mo-enriched molybdenum. The procedure is applied for a routine production of enriched crystals. Furthermore, the technology of a single detector module consisting of a large-volume ($\sim 100$~cm$^3$) Zn$^{100}$MoO$_4$ and Li$_2$$^{100}$MoO$_4$ scintillating bolometer has been established, demonstrating performance and radiopurity that are close to satisfy the demands of CUPID. In particular, the FWHM energy resolution of the detectors at 2615 keV --- near the $Q$-value of the double-beta transition of $^{100}$Mo (3034~keV) --- is $\approx$ 4--10~keV. The achieved rejection of $\alpha$-induced dominant background above 2.6~MeV is at the level of more than 99.9\%. The bulk activity of $^{232}$Th ($^{228}$Th) and $^{226}$Ra in the crystals is below 10 $\mu$Bq/kg. Both crystallization and detector technologies favor Li$_2$MoO$_4$, which was selected as a main element for the realization of a CUPID demonstrator (CUPID-0/Mo) with $\sim$7 kg of $^{100}$Mo

Advances in structure elucidation of small molecules using mass spectrometry

The structural elucidation of small molecules using mass spectrometry plays an important role in modern life sciences and bioanalytical approaches. This review covers different soft and hard ionization techniques and figures of merit for modern mass spectrometers, such as mass resolving power, mass accuracy, isotopic abundance accuracy, accurate mass multiple-stage MS(n) capability, as well as hybrid mass spectrometric and orthogonal chromatographic approaches. The latter part discusses mass spectral data handling strategies, which includes background and noise subtraction, adduct formation and detection, charge state determination, accurate mass measurements, elemental composition determinations, and complex data-dependent setups with ion maps and ion trees. The importance of mass spectral library search algorithms for tandem mass spectra and multiple-stage MS(n) mass spectra as well as mass spectral tree libraries that combine multiple-stage mass spectra are outlined. The successive chapter discusses mass spectral fragmentation pathways, biotransformation reactions and drug metabolism studies, the mass spectral simulation and generation of in silico mass spectra, expert systems for mass spectral interpretation, and the use of computational chemistry to explain gas-phase phenomena. A single chapter discusses data handling for hyphenated approaches including mass spectral deconvolution for clean mass spectra, cheminformatics approaches and structure retention relationships, and retention index predictions for gas and liquid chromatography. The last section reviews the current state of electronic data sharing of mass spectra and discusses the importance of software development for the advancement of structure elucidation of small molecules

Quantum coherence of multiple excitons governs absorption cross-sections of PbS/CdS core/shell nanocrystals

半導体ナノ粒子の光吸収効率の増加メカニズムを解明 --高効率な太陽電池や光検出器へ期待--. 京都大学プレスリリース. 2018-08-22.Multiple excitons in semiconductor nanocrystals have been extensively studied with respect to unique carrier dynamics including quantized Auger recombination and implementation in optoelectronic devices such as solar cells and photodetectors. However, the generation mechanism of multiple excitons still remains unclear. Here, we study instantaneous and delayed multiple exciton generation processes in PbS/CdS core/shell nanocrystals. The absorption cross-sections of biexcitons and triexcitons are identical to that of single excitons under instantaneous excitation with a single pulse. In contrast, the delayed excitation using double pulses shows a reduction of the biexciton and triexciton absorption cross-sections. Our theoretical analysis reveals that the excitonic coherence assists the generation of multiple excitons and that the reduction of multiple exciton absorption cross-sections is caused by the reduction of coherent excitation pathways. We clarify that exciton coherences play a key role in multiple exciton generation processes and seamlessly connect the identical and reduced multiple exciton absorption cross-sections