12 research outputs found
On the problem of interactions in quantum theory
The structure of representations describing systems of free particles in the
theory with the invariance group SO(1,4) is investigated. The property of the
particles to be free means as usual that the representation describing a
many-particle system is the tensor product of the corresponding single-particle
representations (i.e. no interaction is introduced). It is shown that the mass
operator contains only continuous spectrum in the interval
and such representations are unitarily equivalent to ones describing
interactions (gravitational, electromagnetic etc.). This means that there are
no bound states in the theory and the Hilbert space of the many-particle system
contains a subspace of states with the following property: the action of free
representation operators on these states is manifested in the form of different
interactions. Possible consequences of the results are discussed.Comment: 35 pages, Late
Point-Form Analysis of Elastic Deuteron Form Factors
Point-form relativistic quantum mechanics is applied to elastic
electron-deuteron scattering. The deuteron is modeled using relativistic
interactions that are scattering-equivalent to the nonrelativistic Argonne
and Reid '93 interactions. A point-form spectator approximation (PFSA)
is introduced to define a conserved covariant current in terms of
single-nucleon form factors. The PFSA is shown to provide an accurate
description of data up to momentum transfers of 0.5 , but falls
below the data at higher momentum transfers. Results are sensitive to the
nucleon form factor parameterization chosen, particularly to the neutron
electric form factor.Comment: RevTex, 31 pages, 1 table, 13 figure
The deuteron: structure and form factors
A brief review of the history of the discovery of the deuteron in provided.
The current status of both experiment and theory for the elastic electron
scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic
Low-Frequency Magnetic Scanning Device and Algorithm for Determining the Magnetic and Non-Magnetic Fractions of Moving Metallurgical Raw Materials
The development of an algorithm to automate the process of measuring the magnetic properties of macroscopic objects in motion is an important problem in various industries, especially in ferrous metallurgy and at factories where ferrous scrap is a strategic raw material. The parameter that requires work control is the hidden mass fraction of a non-magnetic substance that is present in the ferromagnetic raw material. The solution to this problem has no prototypes. In our work, a simple measuring device and a mathematical algorithm for calculating the mass fraction of the non-magnetic fraction in a strongly magnetic matrix were developed. The device is an inductance coil, in which the angle of the electromagnet losses is related to the mass of the magnetic material moving the coil. The magnitude of the instantaneous values of the lost angle integral was compared with the result of weighing the object on scales. This allowed us to calculate the proportion of the magnetic and non-magnetic fractions. The use of this prototype is herein illustrated. The experimental results of the determination of the magnetic-fractional composition depending on the mass of scrap metal and its bulk and the magnetic characteristics are presented
Photoinduced Transition from Quasi-Two-Dimensional Ruddlesden–Popper to Three-Dimensional Halide Perovskites for the Optical Writing of Multicolor and Light-Erasable Images
Optical
data storage, information encryption, and security labeling
technologies require materials that exhibit local, pronounced, and
diverse modifications of their structure-dependent optical properties
under external excitation. Herein, we propose and develop a novel
platform relying on lead halide Ruddlesden–Popper phases that
undergo a light-induced transition toward bulk perovskite and employ
this phenomenon for the direct optical writing of multicolor patterns.
This transition causes the weakening of quantum confinement and hence
a reduction in the band gap. To extend the color gamut of photoluminescence,
we use mixed-halide compositions that exhibit photoinduced halide
segregation. The emission of the films can be tuned across the range
of 450–600 nm. Laser irradiation provides high-resolution direct
writing, whereas continuous-wave ultraviolet exposure is suitable
for recording on larger scales. The luminescent images created on
such films can be erased during the visualization process. This makes
the proposed writing/erasing platform suitable for the manufacturing
of optical data storage devices and light-erasable security labels
Photoinduced Transition from Quasi-Two-Dimensional Ruddlesden–Popper to Three-Dimensional Halide Perovskites for the Optical Writing of Multicolor and Light-Erasable Images
Optical
data storage, information encryption, and security labeling
technologies require materials that exhibit local, pronounced, and
diverse modifications of their structure-dependent optical properties
under external excitation. Herein, we propose and develop a novel
platform relying on lead halide Ruddlesden–Popper phases that
undergo a light-induced transition toward bulk perovskite and employ
this phenomenon for the direct optical writing of multicolor patterns.
This transition causes the weakening of quantum confinement and hence
a reduction in the band gap. To extend the color gamut of photoluminescence,
we use mixed-halide compositions that exhibit photoinduced halide
segregation. The emission of the films can be tuned across the range
of 450–600 nm. Laser irradiation provides high-resolution direct
writing, whereas continuous-wave ultraviolet exposure is suitable
for recording on larger scales. The luminescent images created on
such films can be erased during the visualization process. This makes
the proposed writing/erasing platform suitable for the manufacturing
of optical data storage devices and light-erasable security labels
Identification of HI-Like Loop in CELO Adenovirus Fiber for Incorporation of Receptor Binding Motifs▿
Vectors based on the chicken embryo lethal orphan (CELO) avian adenovirus (Ad) have two attractive properties for gene transfer applications: resistance to preformed immune responses to human Ads and the ability to grow in chicken embryos, allowing low-cost production of recombinant viruses. However, a major limitation of this technology is that CELO vectors demonstrate decreased efficiency of gene transfer into cells expressing low levels of the coxsackie-Ad receptor (CAR). In order to improve the efficacy of gene transfer into CAR-deficient cells, we modified viral tropism via genetic alteration of the CELO fiber 1 protein. The αv integrin-binding motif (RGD) was incorporated at two different sites of the fiber 1 knob domain, within an HI-like loop that we identified and at the C terminus. Recombinant fiber-modified CELO viruses were constructed containing secreted alkaline phosphatase (SEAP) and enhanced green fluorescent protein genes as reporter genes. Our data show that insertion of the RGD motif within the HI-like loop of the fiber resulted in significant enhancement of gene transfer into CAR-negative and CAR-deficient cells. In contrast, CELO vectors containing the RGD motif at the fiber 1 C terminus showed reduced transduction of all cell lines. CELO viruses modified with RGD at the HI-like loop transduced the SEAP reporter gene into rabbit mammary gland cells in vivo with an efficiency significantly greater than that of unmodified CELO vector and similar to that of Ad type 5 vector. These results illustrate the potential for efficient CELO-mediated gene transfer into a broad range of cell types through modification of the identified HI-like loop of the fiber 1 protein
Single-Step Fabrication of Resonant Silicon–Gold Hybrid Nanoparticles for Efficient Optical Heating and Nanothermometry in Cells
Heat is a well-known treatment method for a wide range
of diseases.
Hyperthermia treatment or intentional overheating of cells is a rapidly
developing therapeutic strategy in cancer treatment. All-dielectric
nanophotonics has established itself in optical applications, including
nanothermometry and optical heating; generally, it involves Mie resonances
in nonplasmonic nanoparticles (NPs). However, such nanomaterials do
not always provide sufficient heating due to their nonoptimal size
distribution after fabrication by nonlithographic approaches. To overcome
this limitation, additional steps, such as size-separation of NPs,
are required. Another strategy for efficient heating is intelligent
integration of plasmonic and all-dielectric nanostructures to develop
hybrid nanomaterials with outstanding optical performances, e.g.,
efficient nanoheaters and nanothermometers. Taking this into account,
we report on a simple and accessible approach for the fabrication
of hybrid silicon–gold NPs. Their heating abilities are further
compared with those of pristine monodispersed Si NPs inside and outside
B16–F10 melanoma cells and confirmed by simultaneous nanoscale
thermometry. The obtained results show that the obtained hybrid nanomaterials
are more efficient nanoheaters even in biological environments, where
cell inhomogeneity and deviations of NP sizes make it difficult to
exactly meet the critical coupling conditions