Systematic exploration of the synthesis of mixed-metal Dy-M nitride clusterfullerenes (NCFs, M = Gd, Er, Tm, Lu) is performed, and the impact of the second metal on the relative yield is evaluated. ...We demonstrate that the ionic radius of the metal appears to be the main factor allowing explanation of the relative yields in Dy-M mixed-metal systems with M = Sc, Lu, Er, and Gd. At the same time, Dy-Tm NCFs show anomalously low yields, which is not consistent with the relatively small ionic radius of Tm
but can be explained by the high third ionization potential of Tm. Complete separation of Dy-Gd and Dy-Er, as well as partial separation of Dy-Lu M
N@C
nitride clusterfullerenes, is accomplished by recycling HPLC. The molecular structures of DyGd
N@C
and DyEr
N@C
are analyzed by means of single-crystal X-ray diffraction. A remarkable ordering of mixed-metal nitride clusters is found despite similar size and electronic properties of the metals. Possible pyramidalization of the nitride clusters in these and other nitride clusterfullerenes is critically analyzed with the help of DFT calculations and reconstruction of the nitrogen inversion barrier in M
N@C
molecules is performed. Although a double-well potential with a pyramidal cluster structure is found to be common for most of them, the small size of the inversion barrier often leads to an apparent planar structure of the cluster. This situation is found for those M
N@C
molecules in which the energy of the lowest vibrational level exceeds that of the inversion barrier, including Dy
N@C
and DyEr
N@C
. The genuine pyramidal structure can be observed by X-ray diffraction only when the lowest vibrational level is below the inversion barrier, such as those found in Gd
N@C
and DyGd
N@C
. The quantum nature of molecular vibrations becomes especially apparent when the size of the inversion barrier is comparable to the energy of the lowest vibrational levels.
Energetic compounds containing a new explosophoric fragment, (3,4-dinitro-1
H
-pyrazol-1-yl)-
NNO
-azoxy group, and furazan rings linked by azo and azoxy bridges were synthesized. Furazans obtained ...combine a high calculated enthalpy of formation and acceptable thermal stability and are of interest as potential components of energy-rich materials.
Mathematical modeling uses a wide variety of mathematical methods and concepts, in particular, an ergodic theory that studies statistical properties of motions in measure spaces (dynamic systems). ...The article is devoted to a further study of the statistical properties of a dynamic system generated by number-theoretic endomorphisms. An estimate of the convergence rate in the central limit theorem for sums of functions from number-theoretic endomorphisms trajectories is obtained. The obtained results may be of interest to practitioners using the theory of dynamic systems and specialists in number theory.
There is considered the generalized Bernoulli tests scheme in which it is assumed that the tests are connected unlike the usual Bernoulli tests scheme. There is defined the condition of weak ...dependence of tests. The integral limit theorem is proved for the distribution of the number of successes in carrying out a finite set of tests. There is investigated the convergence rate in the limit theorem. There is obtained the optimal remainder.
The experiment was carried out on 120 female white Wistar rats, to study the endothelio- and osteoprotective action of the combination of rosuvastatin with L-norvaline in the model of experimental ...osteoporosis. It was found that, after ovariectomy in rats, endothelial dysfunction of the vessels of the microcirculatory bed of bone tissue develops, leading to the appearance of osteoporosis, but the combination of the studied drugs prevents the decrease in the level of microcirculation in the bone tissue, thereby preventing the thinning of bone trabeculae and preventing the occurrence of microfractures in them.
Model experimental studies are presented for the flow field of a single jet, the flow parameters of a block jet, the pressure distribution on the bottom screen, and the parameters of the jet flow ...from a model nozzle. When expanding into a vacuum and/or a highly rarefied medium, the conditions for reproducing the relative gas pulse value of the full-scale nozzle block section are met. It is shown that when using specific similarity criteria, it is possible to experimentally model the supersonic jet outflow processes of space vehicles on small-sized laboratory vacuum installations, similar to the one created at Novosibirsk State University. Simulation results using spectral density measurements based on the glow excited by a focused electron beam, longitudinal and transverse jet density profiles obtained using modern scanning technology, as well as measurements of bottom pressure near the nozzle block are given. The possibilities and features of each applied registration method are discussed.
Systematic exploration of the synthesis of mixed-metal Dy–M nitride clusterfullerenes (NCFs, M = Gd, Er, Tm, Lu) is performed, and the impact of the second metal on the relative yield is evaluated. ...We demonstrate that the ionic radius of the metal appears to be the main factor allowing explanation of the relative yields in Dy–M mixed-metal systems with M = Sc, Lu, Er, and Gd. At the same time, Dy–Tm NCFs show anomalously low yields, which is not consistent with the relatively small ionic radius of Tm3+ but can be explained by the high third ionization potential of Tm. Complete separation of Dy–Gd and Dy–Er, as well as partial separation of Dy–Lu M3N@C80 nitride clusterfullerenes, is accomplished by recycling HPLC. The molecular structures of DyGd2N@C80 and DyEr2N@C80 are analyzed by means of single-crystal X-ray diffraction. A remarkable ordering of mixed-metal nitride clusters is found despite similar size and electronic properties of the metals. Possible pyramidalization of the nitride clusters in these and other nitride clusterfullerenes is critically analyzed with the help of DFT calculations and reconstruction of the nitrogen inversion barrier in M3N@C80 molecules is performed. Although a double-well potential with a pyramidal cluster structure is found to be common for most of them, the small size of the inversion barrier often leads to an apparent planar structure of the cluster. This situation is found for those M3N@C80 molecules in which the energy of the lowest vibrational level exceeds that of the inversion barrier, including Dy3N@C80 and DyEr2N@C80. The genuine pyramidal structure can be observed by X-ray diffraction only when the lowest vibrational level is below the inversion barrier, such as those found in Gd3N@C80 and DyGd2N@C80. The quantum nature of molecular vibrations becomes especially apparent when the size of the inversion barrier is comparable to the energy of the lowest vibrational levels.
Systematic exploration of the synthesis of mixed-metal Dy-M nitride clusterfullerenes (NCFs, M = Gd, Er, Tm, Lu) is performed, and the impact of the second metal on the relative yield is evaluated. ...We demonstrate that the ionic radius of the metal appears to be the main factor allowing explanation of the relative yields in Dy-M mixed-metal systems with M = Sc, Lu, Er, and Gd. At the same time, Dy-Tm NCFs show anomalously low yields, which is not consistent with the relatively small ionic radius of Tm
3+
but can be explained by the high third ionization potential of Tm. Complete separation of Dy-Gd and Dy-Er, as well as partial separation of Dy-Lu M
3
N@C
80
nitride clusterfullerenes, is accomplished by recycling HPLC. The molecular structures of DyGd
2
N@C
80
and DyEr
2
N@C
80
are analyzed by means of single-crystal X-ray diffraction. A remarkable ordering of mixed-metal nitride clusters is found despite similar size and electronic properties of the metals. Possible pyramidalization of the nitride clusters in these and other nitride clusterfullerenes is critically analyzed with the help of DFT calculations and reconstruction of the nitrogen inversion barrier in M
3
N@C
80
molecules is performed. Although a double-well potential with a pyramidal cluster structure is found to be common for most of them, the small size of the inversion barrier often leads to an apparent planar structure of the cluster. This situation is found for those M
3
N@C
80
molecules in which the energy of the lowest vibrational level exceeds that of the inversion barrier, including Dy
3
N@C
80
and DyEr
2
N@C
80
. The genuine pyramidal structure can be observed by X-ray diffraction only when the lowest vibrational level is below the inversion barrier, such as those found in Gd
3
N@C
80
and DyGd
2
N@C
80
. The quantum nature of molecular vibrations becomes especially apparent when the size of the inversion barrier is comparable to the energy of the lowest vibrational levels.
The impact of the second metal on the synthesis and molecular structure of Dy-M nitride clusterfullerenes (M = Gd, Er, Tm, Lu) is evaluated systematically.
To evaluate the efficiency of gene delivery in gene therapy strategies for malignant brain tumors, it is important to determine the distribution and magnitude of transgene expression in target tumor ...cells over time. Here, we assess the time- and vector dose-dependent kinetics of recombinant herpes simplex virus (HSV)-1 vector-mediated gene expression and vector replication in culture and in vivo by a recently developed radiotracer method for noninvasive imaging of gene expression (J. G. Tjuvajev et al., Cancer Res., 55: 6126-6132, 1995). The kinetics of viral infection of rat 9L gliosarcoma cells by the replication-conditional HSV-1 vector, hrR3, was studied by measuring the accumulation rate of 2-14C-fluoro-5-iodo-1-beta-D-arabinofuranosyl-uracil (FIAU), a selective substrate for viral thymidine kinase (TK). The level of viral TK activity in 9L cells was monitored by the radiotracer assay to assess various vector doses and infection times, allowing vector replication and spread. In parallel, viral yields and levels of Escherichia coli beta-galactosidase activity were assessed quantitatively. To study vector replication, spread and HSV-1-tk and lacZ gene coexpression in vivo, first- or second-generation recombinant HSV-1 vectors (hrR3 or MGH-1) were injected into s.c. growing rat 9L or human U87 deltaEGFR gliomas in nude rats at various times (8 h to 8 days) and at various vector doses 1 x 10(6) to 2 x 10(9) plaque-forming units (PFUs) prior to imaging. For noninvasive assessment of HSV-1-tk gene expression (124I-labeled FIAU % dose/g), 0.15 mCi of 124I-labeled FIAU was injected i.v. 8 h after the last vector administration, and FIAU positron emission tomography (PET) was performed 48 h later. For the assessment of HSV-1-tk and lacZ gene coexpression, 0.2 mCi of 131I-labeled FIAU was injected i.v. 24 h after the last vector administration. Forty-eight h later, animals were killed, and tumors were dissected for quantitative autoradiographical and histochemical assessment of regional distribution of radioactivity (TK expression measured as 131I-labeled FIAU % dose/g) and coexpressed lacZ gene activity. The rates of FIAU accumulation (Ki) in hrR3-infected 9L cells in culture, which reflect the levels of HSV-1-tk gene expression, ranged between 0.12 and 3.4 ml/g/min. They increased in a vector dose- and infection time-dependent manner and correlated with the virus yield (PFUs/ml), where the PFUs:Ki ratios remained relatively constant over time. Moreover, a linear relationship was observed between lacZ gene expression and FIAU accumulation 5-40 h after infection of 9L cells with a multiplicity of infection of 1.5. At later times (> 52 h postinjection), high vector doses (multiplicity of infection, 1.5) led to a decrease of FIAU accumulation rates, viral yield, and cell pellet weights, indicating vector-mediated cell toxicity. Various levels of HSV-1-tk gene expression could be assessed by FIAU-PET after in vivo infection of s.c. tumors. The levels of FIAU accumulation were comparatively low (approximately ranging from 0.00013 to 0.003% injected dose/g) and were spatially localized; this may reflect viral-induced cytolysis of infected tumor cells and limited lateral spread of the virus. Image coregistration of tumor histology, HSV-1-tk related radioactivity (assessed by autoradiography), and lacZ gene expression (assessed by beta-galactosidase staining) demonstrated a characteristic pattern of gene expression around the injection sites. A rim of lacZ gene expression immediately adjacent to necrotic tumor areas was observed, and this zone was surrounded by a narrow band of HSV-1-tk-related radioactivity, primarily in viable-appearing tumor tissue. These results demonstrate that recombinant HSV-1 vector-mediated HSV-1-tk gene expression can be monitored noninvasively by PET, where the areas of FIAU-derived radioactivity identify the viable portion of infected tumor tissue that retains FIAU accumulation ability, and that the accumulation rate of FIAU in culture, Ki, reflects the number of HSV-1 viral particles in the infected tumor cell population 4.1 +/- 0.6 x 10(6) PFUs/Ki unit (PFUs divided by ml/min/g). Moreover, time-dependent and spatial relationships of HSV-1-tk and lacZ gene coexpression in culture and in vivo indicate the potential for indirect in vivo imaging of therapeutic gene expression in tumor tissue infected with any recombinant HSV-1 vector where a therapeutic gene is substituted for the lacZ gene.
The review presents investigations devoted to development of synthesis techniques and studying properties of nanosized single-domain ferrite spinels. Above-mentioned materials are used for: chemical ...fabrication of magnetosensitive nanocomposites with multilevel hierarchical nanoarchi-tecture and functions of recognition of microbiological objects in biologic media; targeted delivery of drugs into specific cells and organs and deposition; complex chemo-, immuno-, radiology neutron capture, hyperthermic, photodynamic cancer therapy and diagnostics in a real-time regime; adsorption of heavy-metal ions, toxins, cell decomposition debris and elimination of them from the body via the external magnetic field; development of a new generation of magnetosensitive adsorbents for medical, ecology, technical destination, composite nanostructured special materials, media and covers with beforehand set dielectric and magnetic losses to interact effectively with electromagnetic eradiation of super-high-frequency band.
PDF
