Abstract
Terahertz (THz) technology offers a variety of applications in label-free medical diagnosis and therapy, majority of which rely on the effective medium theory that assumes biological tissues ...to be optically isotropic and homogeneous at the scale posed by the THz wavelengths. Meanwhile, most recent research discovered mesoscale (
$$\sim \lambda $$
∼
λ
) heterogeneities of tissues;
$$\lambda $$
λ
is a wavelength. This posed a problem of studying the related scattering and polarization effects of THz-wave–tissue interactions, while there is still a lack of appropriate tools and instruments for such studies. To address this challenge, in this paper, quantitative polarization-sensitive reflection-mode THz solid immersion (SI) microscope is developed, that comprises a silicon hemisphere-based SI lens, metal-wire-grid polarizer and analyzer, a continuous-wave 0.6 THz (
$$\lambda = 500$$
λ
=
500
µm) backward-wave oscillator (BWO), and a Golay detector. It makes possible the study of local polarization-dependent THz response of mesoscale tissue elements with the resolution as high as
$$0.15 \lambda $$
0.15
λ
. It is applied to retrieve the refractive index distributions over the freshly-excised rat brain for the two orthogonal linear polarizations of the THz beam, aimed at uncovering the THz birefringence (structural optical anisotropy) of tissues. The most pronounced birefringence is observed for the Corpus callosum, formed by well-oriented and densely-packed axons bridging the cerebral hemispheres. The observed results are verified by the THz pulsed spectroscopy of the porcine brain, which confirms higher refractive index of the Corpus callosum when the THz beam is polarized along axons. Our findings highlight a potential of the quantitative polarization THz microscopy in biophotonics and medical imaging.
Abstract
Two-dimensional electron systems in a quantizing magnetic field are regarded as of exceptional interest, considering the possible role of anyons—quasiparticles with non-boson and non-fermion ...statistics—in applied physics. To this day, essentially none but the fractional states of the quantum Hall effect (FQHE) have been experimentally realized as a system with anyonic statistics. In determining the thermodynamic properties of anyon matter, it is crucial to gain insight into the physics of its neutral excitations. We form a macroscopic quasi-equilibrium ensemble of neutral excitations - spin one anyon complexes in the Laughlin state
ν
= 1/3, experimentally, where
ν
is the electron filling factor. The ensemble is found to have such a long lifetime that it can be considered the new state of anyon matter. The properties of this state are investigated by optical techniques to reveal its Bose properties.
A novel type of cyclic P,N-ligands, pyridyl containing phospholanes, has been synthesized in a moderate yield by the reaction of primary phosphines with 1,4-dichlorobutane in a superbasic medium. A ...series of homo tetranuclear octahedral Cu4I4L2, dinuclear tetrahedral Cu2I2L3, and dinuclear "head-to-tail" Cu2I2L2 luminescent complexes with these ligands were obtained. All the compounds were characterized using a range of spectroscopic and computational techniques, and in the case of some Cu4I4L2 and Cu2I2L3 complexes, by single crystal X-ray diffraction. The structural diversity of the obtained complexes was reflected in their photophysical properties: phosphorescence spectra of the compounds display emission in broad spectral range of 471-615 nm. TD-DFT computations allow the assignment of a single emission band around 550 nm for Cu2I2L3 complexes and 471 nm for Cu2I2L2 complex to a vertical triplet-singlet transition from a metal-to-ligand and halide-to-ligand charge-transfer (3)(M + X)LCT excited state, whereas a second band at around 600 nm in the spectra of octahedral Cu4I4L2 complexes was assigned predominantly to Cu4I4 cluster-centered ((3)CC) excited state.
Copper(
ii
) and manganese(
ii
) chelate complexes were synthesized using the new
N,O
-hybrid ligand 1,3-dibenzhydryl-5-(pyridin-2-yl)-1,3,5-diazaphosphinane 5-oxide. The synthesized complexes were ...characterized by physicochemical methods. The molecular and crystal structures of the complexes were established by X-ray diffraction. All new compounds were evaluated for cytotoxicity against the cancer cell lines M-HeLa and HuTu80 and the normal cell line Chang liver.
A series of dimeric gold(I) complexes L
2
Au
2
Cl
2
has been synthesized by the reaction of equimolar amounts of 10-(aryl)phenoxarsine ligands with chloro(tetrahydrothiophene)gold(I). The structure ...of complexes
4
–
6
has been confirmed by a combination of physicochemical methods. The crystal structure of complex
4
has been determined by single-crystal X-ray diffraction. The Tolman angles have been calculated for the known tertiary arsine ligands and the ligands in the synthesized gold complexes. It has been shown that the dimeric structure of the complexes is formed through the aurophilic interaction between two monomers. The Tolman angle of the phenoxarsine ligand plays a significant role in this interaction; in the dimeric complexes, this angle is on average 147°.
New bi- and trinuclear gold(I) complexes are synthesized by the reactions of gold(I) chloride or tetrahydrothiophenegold(I) chloride with 1,5-di(
p
...-tolyl)-3,7-diphenyl-1,5,3,7-diazadiphosphacyclooctane taken in various ratios. The structures of the synthesized compounds are confirmed by NMR spectroscopy, elemental analysis, and X-ray diffraction analysis (CIF files ССDC nos. 1974032 (
I
) and 1974031 (
II
)). Unlike P-pyridyl-containing 1,5-diaza-3,7-diphosphacyclooctanes, P-phenyl-substituted ligands undergo no rearrangements with ring expansion during the formation of the trinuclear gold(I) complexes.
1D coordination silver(I) polymer L
2
AgONO
2
n
has been obtained via the reaction of 10-(4-ethoxyphenyl)phenoxarsine with silver(I) nitrate (metal : ligand molar ratio 1 : 2) in ethanol. The ...complex has been identified and characterized by a set of physicochemical methods of analysis (mass spectrometry,
1
H NMR spectroscopy, elemental analysis, and X-ray diffraction analysis). The ligand and its Ag(I) complex have been evaluated for cytotoxicity against the cancer cell lines M-HeLa and HuTu 80 and the normal cell line Chang liver; antimicrobial activity of the complex against a series of Gram-positive and Gram-negative bacteria has been investigated.
New 1-aza-3,5-diphosphorinanes have been synthesized as a mixture of
RR
/
SS-
and
RS
-isomers via the reaction of bis(phenylphosphanyl)methane, paraformaldehyde, isopropylamine, of benzhydrylamine.
A new method has been proposed for the synthesis of bis(phosphine sulfides) and nickel and platinum chelate complexes of 1,3,6-azadiphosphacycloheptanes. The method is based on the ability of ...14-membered 3,6,10,13-diazadiphosphacyclotetradecanes to undergo a reversible transformation in solutions into a mixture of
meso-
and
rac
-isomers of seven-membered bis-phosphines. The reaction of 3,6,10,13-diazadiphosphacyclotetradecanes with elementary sulfur results in 14-membered tetrakis(phosphine sulfides) or seven-membered bis(phosphine sulfides), depending on the reaction conditions. The reaction of 1,3,6-azadiphosphacycloheptanes, resulting from the reversible dissociation of 14-membered tetraphosphines in chloroform, with Ni(CH
3
CN)
6
(BF
4
)
2
and Pt(COD)Cl
2
gives the corresponding chelate complexes. The structures of the
meso
-isomer of 1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane-3,6-disulfide, bis-(κ
2
-1-isopropyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)nickel bis(tetrafluoroborate), bis-(κ
2
-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)chloronickel tetrafluoroborate, and
cis
-dichloro-(κ
2
-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)platinum(II), isolated in crystalline form, have been confirmed by single crystal X-ray diffraction.
New 1,5,3,7-diazadiphosphacyclooctanes with N,O-, N,N-, N,S-, and N,N,S-heterocyclic substituents at the nitrogen atoms have been synthesized. The influence of the nature of amines containing
sp
2
...-hybridized nitrogen atom in the
ortho
-position of the heterocyclic substituent on the result of Mannich condensation in phosphine–paraformaldehyde–primary amine system has been revealed. The stabilization of intermediate acyclic products—aminomethyl(hydroxymethyl)arylphosphines and bis(aminomethyl)arylphosphines—due to amino–imine tautomerism is responsible for the low yield of the target cyclic diphosphines based on the above amines.
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