Unusual intrinsic thermoluminescence in LiMgPO4:Er.

Olivine-type phosphate LiMgPO4 doped with rare-earth elements is currently considered as a new dosimetric material suitable for both OSL and TSL applications and able to compete with top commercial detectors. In this work, the samples of LiMgPO4:Er3+ were synthesized by the conventional solid state reaction method. We first studied X-ray luminescence and thermally and optically stimulated luminescence in LiMgPO4:Er3+ in detail. Our studies included the structure refinement, DFT calculations, which predicted the preferred positions of both erbium and charge-compensating vacancies, and UV-vis spectroscopy. We showed that the thermoluminescence spectrum of irradiated LiMgPO4:Er3+ does not contain components caused by the 4f-4f transitions in erbium, but coincides with the spectrum of the phosphate matrix with two broad bands at 360 nm and 650 nm. We discovered a high OSL and TSL output in LiMgPO4:Er3+, despite the nonradiative deexcitation of erbium ions.

New Li-Mg phosphates with a 3D framework: experimental and ab initio calculations.

Two new lithium-magnesium phosphates LiMg6(PO4)3(P2O7) and Li(Mg5.62Sc0.19Li0.19)(PO4)3(P2O7) were synthesized by a solid-phase method. Using high-resolution time-of-flight neutron powder diffraction (TOF NPD) and X-ray powder diffraction (XRPD), we established that these phosphates have a Pnma orthorhombic structure with the cell parameters a = 9.14664(5) Å, b = 18.83773(8) Å, c = 8.27450(4) Å, and V = 1425.71(1) Å3 and a = 9.14516(5) Å, b = 18.84222(9) Å, c = 8.28204(4) Å, and V = 1427.12(1) Å3, respectively. The crystal structures can be described by stacking of the [Mg6O18]∞ or [Mg5.62Sc0.19Li0.19O18]∞ wavy layers, which are parallel to the (100) direction and interconnected through PO4 tetrahedra and P2O7 groups to form a 3D-framework. The Li atoms are located in large tunnels formed in a 3D lattice, which contributes to lithium diffusion. AC impedance spectroscopy analysis shows that LiMg6(PO4)3(P2O7) and Li(Mg5.62Sc0.19Li0.19)(PO4)3(P2O7) have a Li ion conductivity of 3.6 × 10-4 S cm-1 and 1.7 × 10-4 S cm-1 at 950 °C, with an activation energy of 1.28 eV and 1.55 eV, respectively. NMR MAS studies confirmed the coexistence of pyro- and orthogroups in the structure of both phases and two lithium positions in Li(Mg5.62Sc0.19Li0.19)(PO4)3(P2O7). The first-principles method was used to study the electronic structure and stability of the two phases. The calculated formation enthalpies demonstrated that Sc is a stabilizing impurity in LiMg6(PO4)3(P2O7), while a strong destabilization of olivine LiMgPO4 is observed upon doping with Sc. This explains the failure to synthesize Sc-doped olivine. The new phosphate LiMg6(PO4)3(P2O7) is a dielectric with a band gap of 5.35 eV, which decreases to 4.85 eV due to the appearance of a localized Sc 3d peak upon doping with Sc. These findings are consistent with the results obtained by UV-Vis spectroscopy. The new phase may be a good optical matrix similar to LiMgPO4.

[Synthesis and Anticancer Activity of Betulonic Acid Imidazolides].

Synthesis of lupane C28-imidazolides, contained 3-oxo-, 3-oximino- and 2-cyano-2,3-seco-4(23)-en-frag ments in cycle A was carried out. The most antitumor activity at. in vitro testing showed 3-oximino-lup- 20(29)-en-28-yl-1H-imidazole-1-carboxylate; which inhibited the growth or induced apoptosis of non-small lung cancer, colon cancer, breast cancer, CNS cancer, ovarian cancer, prostate cancer, leucosis, melanoma cells. In experiments in mice its moderate antitumor activity against grafted breast adenocarcinoma Ca 755 and adenocarcinima of colon was observed.

[Synthesis and cytotoxicity of triterpenoid seven members cyclic amines].

Synthesis of 3-deoxy-3a-homo-3a-aza-derivatives of betulin and erythrodiol from betulonic and oleanonic acids was carried out. The most antineoplastic activity with a wide range of action at in vitro testing showed 3-deoxy-3a-homo-3a-aza-28-hydroxy-12(13)-oleanene, which by results of profound studying could be recommended for in vivo investigation. Its modification in the C28 position by introduction of amethoxycinnamoyl fragment led to a loss of antineoplastic activity. 3-Deoxy-3a-homo-3a-aza-derivatives of betulin (3-(aminopropyl)-, 28-(2-carboxyethyl)carboxy-, and 28-cinnamoyloxy-) showed moderate antineoplastic activity in the case of Colon Cancer, Breast Cancer and Leukemia cell lines.

[Synthesis and cytotoxicity of allobetulin derivatives].

The synthesis and screening of antitumor activity in vitro (cytotoxicity) of various oxygen, nitrogen, sulfur and platinum-containing derivatives of allobetulin, including different arrangements of the double bonds in the A and B rings, penta- and hexacyclic ring A, 21-acetyl-20,28-epoxy-18α,19ßH-ursane-isomeric cycle E, was carry out. (3R,5R)-19ß,28-Epoxy-4,5-seco-18α-olean-3(5)-ozonide and 2,3-indolo-21ß-acetyl-20ß,28-epoxy-18α, H-19ß-ursane showed significant cytotoxic activity against melanoma MeWo and Leukemia SR cells, appropriately. (3S,5S)-Diastereomer of the first compound showed no cytotoxicity.

[Synthesis, structure and farmacologycal activity of (7R,8S)-epoxy-(13R,17R)-trioxolaneabietic acid].

The synthesis and X-ray diffraction established the structure of (7R,8S)-(see text for symbol)-(13R,17R)-trioxolaneabietic acid. Predicted by the computer system PASS antineoplastic activity and the ability to induce apoptosis, a mechanism of cell death, is correlated with experimentally shown cytotoxic activity against malignant cell line MeWo. Results of tests on animals have shown that abietic acid and its 9R,11S-epoxy-12R,15R-trioxolane derivative have anti-inflammatory and antiulcer activity in the absence of adverse effects on animal organisms.

[Synthesis of aminopropylaminoderivatives of betulinic and oleanolic acids].

On the basis of betulinic and oleanolic acids triterpenoids with different with different amine fragments: (3-aminopropoxy)-, 3-acetyl-(3-aminopropyl)amino-, 6-[bis(3-aminopropyl)amino]hexylamino-, (3-aminopropyl)-4-aminosulfonyl-4-phenylamino- at positions C3 and C28 were synthesized. It is shown that betulonic acid amide with 4,4'-diaminodiphenylsulfonic substituent don't render antitumor effect in mice with transplantable Lewis lung carcinoma, but possess significant anti-inflammatory activity.

The effect of carbon distribution on the manganese magnetic moment in bcc Fe-Mn alloy.

First-principles calculations were performed to study the structural, electronic, and magnetic properties of bcc Fe with C impurities alloyed with 2, 3, and 6 at.% of Mn. Our results reveal that both manganese concentration and carbon location with respect to Mn affect the Fe-Mn magnetic interaction. With an increase in Mn concentration in bcc Fe-Mn alloy, the local magnetic moment of manganese changes sharply from - 2 to 1 µ(B) near 3 at.% Mn, while carbon stabilizes the local ferromagnetic interaction between the nearest Mn atom and the Fe matrix. We demonstrate that the Mn-C interaction is attractive and promotes carbon trapping with a low energy defect configuration. Our results indicate that the Mn-C binding energy strongly depends on the magnetism and the formation of Mn(x)C clusters is predicted.

[Structural and functional characteristics of betulin derivatives].

The effect of betulin derivatives on persistence properties of microorganisms was studied in vitro. It was shown that the antipersistence action of the betulin derivatives depended on their structure and the microbial species. The experimental data on the structure - function relation could be useful in development and synthesis of new agents for therapy of chronic infections associated with persistence of bacterial pathogens in macroorganism.

[Synthesis, modifications, and antimicrobial activity of the methylpiperazinyl amides of triterpenic acids].

N-Methylpiperazinyl amides of betulinic, platanic, glycyrrhetic, oleanolic, ursolic, and moronic acids were synthesized and modified. Betulin and betulonic acid showed antimicrobial activity against Staphylococcus aureus at a concentration of 90 mg/ml, and betulin manifested a bacteriostatic effect against Klebsiella pneumoniae at a concentration of 60 mg/ml. Among the studied N-methylpiperazinyl amides, the highest activity against S. aureus was observed for a betulonic acid derivative.

[Synthesis of triterpenoid acylates - an effective reproduction inhibitors of influenza A (H1N1) and papilloma viruses].

The synthesis of a new group of triterpenoid acylates on the basis of oleanolic, glycyrrhetic and ursolic acids and betulin is described. In studying the activity of the synthesized compounds in relation to reproduction of virus pathogens of respiratory infections 28-O-methoxycynnamoylbetulin shows high activity against influenza type A (H1N1) the selectivity index SI > 100. The high activity of 3,28-dinicotinoylbetulin against papilloma virus (strain HPV-11) was detected, the selectivity index SI was 35.

Magnetism in bcc and fcc Fe with carbon and manganese.

Density functional theory calculations were performed to study the structure and magnetic properties of bcc (α) and fcc (γ) Fe with 3 at.% carbon and manganese impurities. We find that all bcc-based Fe, Fe-C and Fe-Mn-C phases exhibit a ferromagnetic (FM) ground state, while the antiferromagnetic double-layer (AFMD) state is lowest in energy within the collinear spin approach in fcc Fe, Fe-C and Fe-Mn-C phases. However, the carbon and manganese impurities affect the local magnetic interactions significantly. The states with opposite manganese magnetic moments are quasi-degenerate in bcc Fe-Mn alloy, whereas octa-site carbon stabilizes ferromagnetic coupling of the nearest manganese atom with the Fe host. We demonstrate that the antiferromagnetic (AFM) fcc Fe-C and Fe-Mn-C alloys are intrinsically inhomogeneous magnetic systems. Carbon frustrates the local magnetic order by reorientation of magnetic moments of the nearest Mn and Fe atoms, and favors their ferromagnetic coupling. The competition between ferromagnetic and antiferromagnetic Fe-Fe and Fe-Mn interactions and the local magnetovolume instability near carbon may give rise to the spin-glass-like regions observed in austenitic Fe-Mn-C alloys.

Synthesis of triterpenoid acylates: Effective reproduction inhibitors of influenza A (H1N1) and papilloma viruses.

The synthesis of a new group of triterpenoid acylates has been conducted on the basis of oleanolic, glycyrrhetic, and ursolic acids and betulin. 28-ortho-Methoxycynnamoylbetulin has been demonstrated to possess high activity against the influenza type A (H1N1) virus with the selectivity index SI > 100 while studying the activity of the synthesized compounds in relation to the reproduction of viral pathogens of respiratory infections. The high activity of 3,28-dinicotinoylbetulin against the papilloma virus (strain HPV-11) was detected with the selectivity index SI 35.

[Synthesis of olean-18(19)-ene derivatives from betulin].

The rare olean-18(19)-ene triterpenoids moradiol and moronic acid were synthesized from betulin, and their antiviral properties were investigated.

[Betulonic amides modified at the ring A by amino acids: synthesis and inhibition of influenza A virus reproduction].

The Beckman rearrangement of carboxy- and alkyloxycarbonylalkylamides of 3-hydroxyiminobetulonic acid led to derivatives of 3a-homo-4-aza-3-oxolup-20(29)-ene and 3,4-seco-2-cyanolupa-4(23),20(29)-diene. An X-ray analysis showed methyl 3-(N-acetoximino)lup-20(29)-enoate is the E-isomer. The compounds synthesized exhibited inhibiting activity toward the reproduction of flu A virus in cell culture.

[Synthesis and antiviral activity of lupane triterpenoids with modified cycle E].

A reductive transformation of the peroxide products of ozonolysis of derivatives of 3beta-O-acetyl-22(17-->28)-abeo-lupa-17(28),20(29)-diene and the subsequent intramolecular ketalization led to a compound with a trioxane fragment. This is a new approach to a skeletal modification of triterpenoid cycle E. An activity of the synthesized compounds was found toward the viruses of type A influenza and herpes simplex.

Electronic origin of solid solution softening in bcc molybdenum alloys.

The intrinsic mechanism of solid solution softening in bcc molybdenum alloys due to 5d transition metal additions is investigated on the basis of ab initio electronic-structure calculations that model the effect of alloying elements on the generalized stacking fault (GSF) energies. We demonstrate that additions with an excess of electrons (Re, Os, Ir, and Pt) lead to a decrease in the GSF energy and those with a lack of electrons (Hf and Ta) to its sharp increase. Using the generalized Peierls-Nabarro model for a nonplanar core, we associate the local reduction of the GSF energy with an enhancement of double kink nucleation and an increase of the dislocation mobility, and we reveal the electronic reasons for the observed dependence of the solution softening on the atomic number of the addition.

[Experimental-clinical substantiation of the use of micro-lamellar keratotomy combined with kerato-thermocoagulation in the correction of hypermetropia]. / Eksperimental'no-klinicheskoe obosnovanie primeneniia mikrolamelliarnoi keratotomii v kombinatsii s termokeratokoaguliatsiei dlia korrektsii gipermetropii.

The article describes the methods for the correction of hypermetropia, i.e. micro-lamellar keratotomy (MLK) and MLK plus thermokeratocoagulation (MLKTKC). The experiment was made on 6 rabbits (12 eyes). Lamellar corneal incisions were implemented by ALK ACS system (USA) to a depth of 73-75% of the corneal thickness. Simultaneously, thermokeratocoagulation (TKC) to 80% of the corneal thickness was made in a part of animals in meridians 6, 8, 10 and 12 (an 8 mm optic zone and 3 to 4 coagulates in each meridian). Postoperatively, the keratometric data were evaluated in 1, 3 and 6 months. The corneal optic power went up, postoperatively, in the center by around 4.0 diopters in cases, when the common surgical technique was used, and it went up to 5.0-9.0 diopters, when the common technique was combined with TKC. A clinical approbation of the MLK and MLKTKC methods in adults with hypermetropia (44 operations, mean age 29.3 years) showed their efficiency and safety. The corneal refraction improvement ranged from 3.5 diopters to 7.5 diopters (mean 4.49 +/- 0.89 diopters). The developed method of the above surgeries (the diameter of the modeled optic zone is 5 mm, the lamellar depth incision is 73%) prevents the complications, which lead to irreversible changes of the cornea; besides, it makes it possible to preserve a sufficiently wide central optic zone with a present refraction. This study provided a foundation for the clinical use of the method in pediatric practice.

[Choice of a surgical correction method in hypermetropic anisotropia in children]. / Vybor metoda khirurgicheskoi korrektsii gipermetropicheskoi anizometropii u detei.

The results of surgical techniques applicable to hypermetropia correction, i.e. lamellar keratotomy (LK), lamellar keratotomy with thermal keratocoagulation (LKTKC) and sub-flap photokeratectomy (LASIK), in 80 children, aged 6 to 14, with hypermetropia ranging from 3.5 to 9.5 diopters and with astigmatism ranging from 0.75 to 2.75 diopters are analyzed. The follow-up varied from 1 to 3 years. LASIK (reduction of astigmatism by 1.61 +/- 0.43 diopters or 78%) was proven to be an optimal method in the correction of astigmatic hypermetropic anisometropia. LASIK (reduction of anisometropia by 3.44 +/- 0.44 diopters or 80%) is preferable in the correction of a spherical hypermetropic anisometropia of up to 3.0 diopters inclusively; the LK method (an improvement of clinical refraction by 4.37 +/- 0.87 diopters) is effective in anisometropia of 3.0 to 5.5 diopters; and LKTKC is effective in anisometropia of 5.5 to 7.5 diopters. The latter ensures an improvement of the corneal refraction by more than 2 diopters (2.15 +/- 0.44 diopters) versus LK. TKC is possible as a single-stage procedure made in the remote time period. LASIK is more preferable in astigmatism of more than 1.5 diopters.

[Improvement of the method of prehospital protection of vision]. / Usovershenstvovanie sposoba dogospital'noi okhrany zreniia.

The authors describe an improved method for the prevention of ocular diseases in children, consisting in formation of risk groups starting from female consulting centers ("provisional" group), then at maternity hospitals ("provisional" and "reliable" groups), and then at the outpatient clinic after examination by an ophthalmologist ("actual" and "reliable" groups). This work does not require extra staff or finances, and it helps reduce the incidence of ocular diseases, poor vision, and blindness almost twofold.