Low-energy excitations in NaV2O5

In the (ab) polarized Raman scattering spectra of NaV2O5 single crystals, measured with 647.1 nm laser line at T < Tc, we found two modes at 86, and 126 cm-1 not previously reported. These two modes, together with 66, and 106 cm-1 modes, make an array of four low-energy equidistant modes below the energy onset of the continuum at about 132 cm-1. All four modes are strongly suppressed by increasing Na deficiency, indicating their nonvibrational origin and the existence of a quantum phase transition at critical Na deficiency between 3 and 4%. These results question current understanding of NaV2O5 as quasi one-dimensional Heisenberg antiferromagnet.Comment: 6 pages, 3 figure

benzothiophene and steroidal derivatives of aminoquinoline

Botulinum neurotoksini su najjaĉi poznati prirodni otrovi i izazivaĉi botulizma – potencijalno smrtonosne neuroparalitiĉke bolesti. U poslednje vreme, sve veći broj studija je usmeren ka pronalaţenju inhibitora botulinum neurotoksina serotipa A (BoNT/A) aktivnih unutar ćelije, jer terapija antitelima ima uspeha jedino pre nego što toksin uĊe u neuron. U okviru ove doktorske disertacije izvršena je sinteza i detaljno ispitivanje inhibitorne aktivnosti novih steroidnih i benzo[b]tiofenskih derivata 4-aminohinolina prema kratkom nizu (BoNT/A LC) i holotoksinu BoNT/A. U istraţivanju je korišćen proteolitiĉki in vitro esej i ćelijski esej u motornim neuronima razvijenim iz embrionalnih matiĉnih ćelija miša (mES-MN). Dodatno, molekulsko modelovanje i uklapanje novih derivata u aktivno mesto enzima izvršeno je korišćenjem programa Schr dinger Suite 2016-4. U in vitro proteolitiĉkom eseju, sintetisana jedinjenja su ostvarila do 85% inhibicije BoNT/A LC pri koncentraciji 20 μM, dok su IC50 vrednosti bile u opsegu 0,7– 10,2 μM. U preintoksikacionom modelu u motornim neuronima razvijenim iz embrionalnih matiĉnih ćelija miša (mES-MN) novi derivati su vršili zaštitu proteina SNAP-25i do 88%, u niskim mikromolarnim koncentracijama i u dozno-zavisnom reţimu. Najaktivniji derivati su testirani u postintoksikacionom modelu, u kome se jedinjenja dodaju ćelijskoj kulturi 30 ili 60 minuta posle holotoksina. U oba modela je uoĉena korelacija procenta zaštite SNAP-25 i primenjene koncentracije jedinjenja. Jedinjenje 17 (JK141) je pokazalo 99% zaštite SNAP-25 kada se administrira 30 minuta posle BoNT/A...Botulinum neurotoxins are the most poisonous (biological) substances known and causative agents of botulism – serious and potentially fatal neuroparalytic illness. Recently, the majority of efforts have focused on identification of botulinum neurotoxin serotype A (BoNT/A) inhibitors with intracellular activity, because antibody-based treatments are successful only before toxin enters a neuron. In this doctoral dissertation synthesis and detailed evaluation of inhibitory potencies of new steroidal and benzo[b]thiophene 4-aminoquinoline derivatives against BoNT/A light chain (LC) and full length BoNT/A is reported. Both in vitro proteolytic assay and cell-based assay using mouse embryonic stem cell derived motor neurons (mES-MNs) were employed. To rationalize the inhibitory potencies of the new derivatives, structure-based docking simulations were performed using Schr dinger Suite 2016-4 and the modules therein. Using in vitro HPLC-based assay, the newly synthesized molecules have shown BoNT/A LC inhibition up to 85% at 20 μM and IC50 values ranging from 0.7–10.2 μM. Compounds tested during BoNT/A challenge in mES-MNs in preintoxication model were found to protect SNAP-25 proteinii by up to 88% at low μM concentrations and in dose-dependent manner. The most effective derivatives were also tested in a postexposure model, where compounds were added 30 or 60 minutes following holotoxin administration. In both pre- and postintoxication models, dose-dependent behavior was observed. Compound 17 (JK141) showed 99% of SNAP-25 cleavage protection when administrated 30 minutes after BoNT/A..

Possibilities of reconstruction and implant-prosthetic rehabilitation following mandible resection

Introduction. Mandible reconstruction is still very challenging for surgeons. Mandible defects could be the consequence of ablative surgery for malignancies, huge jaw cysts, infection and trauma. Segmental resection of the mandible may compromise orofacial function and often lead to patients psychological disorders. Despite very frequent use of microvascular flaps, autogenous bone grafts are still very reliable technique for mandible reconstruction. Comprehensive therapy means not only mandible reconstruction, but prosthodontic rehabilitation supported by dental implants, which can significantly improve patients quality of life. The aim of this paper was to evaluate possible techniques of mandible reconstruction and to present a patient who had been submitted to mandible resection and reconstruction with autogenous iliac bone graft and prosthodontic rehabilitation with fixed denture anchoraged by disc-shaped implants in early loading protocol. Case report. Mandible reconstruction was performed simultaneously with resection. Autogenous iliac bone graft was taken, reshaped and placed in two parts, to the required optimal contour of the mandible. After graft consolidation, decision was made for prosthodontics rehabilitation with fixed dentures supported by implants. In addition to the standard preoperative procedures, planning was done based on a biomodel gained by rapid prototyping after CT scan. It offered a real 3D planning to obtain a proper shape, dimension and the position of implants. Conclusion. If bone dimensions of a reconstructed mandible are insufficient, like in the presented case, the use of basal osseointegrated implants may be a method of choice. Avoiding bone augmentation procedures, as well as early loading protocol for this type of implants, shorten the total rehabilitation time, which is very convenient for patients. Fixed denture supported by dental implants is the best solution for comprehensive rehabilitation after mandible resection. [Projekat Ministarstva nauke Republike Srbije, br. 175075

Infrared and Raman spectra of LiV2O5 single crystals

The phonon dynamics of LiV2O5 single crystals is studied using infrared and Raman spectroscopy techniques. The infrared-active phonon frequencies and dielectric constants are obtained by oscillator fitting procedure of the reflectivity data measured at room temperature. The Raman scattering spectra are measured at room temperature and at T=10 K in all nonequivalent polarized configurations. The assignment of the phonons is done by comparing the infrared and Raman spectra of LiV2O5 and NaV2O5. The factor-group-analysis of the LiV2O5 crystal symmetry and of its constituent layers is performed to explain the symmetry properties of the observed modes. We concluded that layer symmetry dominates in the vibrational properties of this compound.Comment: 10 pages, 5 figure

Properties of in vitro constructed DNA elements responsible for gene activity cloned in Escherichia coli – properties of new PLtl promoter

Конструисан је нови PLtl промотор који је састављен од оператора и промоторских секвенци tac и –35 do -135 региона PL промотора фага ʎ који садржи АТ богати регион, као и OL2 и OL3 регионе .Поређене су транскрипционе особине са tac i P помотором. PLtl промотор поседује следеће особине: (i) када је под репресијом експресија гена је занемарљива; (ii) након индукције PLtl промотер показује 1.4 – 2 пута већу активностt; (iii) PLtl промотор омогућава контролу репресора и тиме омогућује успешну експресију производа непознатих карактеристика.The newly constructed PLtl hybrid promoter is composed of the operator and promoter sequences of tac and the -35 to -135 region of the phage lambda PL promoter, which contains the AT-rich block and the OL2 and OL3 segments. Transcriptional properties of PLtl were examined and compared with tac and lambda PL as reference promoters. The hybrid PLtl exhibits different and improved properties over tac promoter in four ways: (i) when repressed, the repression is almost complete; (ii) after complete induction, the hybrid PLtl promoter shows a 1.4-2 times higher expression; (iii) the hybrid PLtl promoter permits flexible gene expression because it can be utilized under either or both repression controls simultaneously; (iv) the PLtl promoter permits enhanced expression of genes encoding products with unknown properties

Thermopower in the strongly overdoped region of single-layer Bi2Sr2CuO6+d superconductor

The evolution of the thermoelectric power S(T) with doping, p, of single-layer Bi2Sr2CuO6+d ceramics in the strongly overdoped region is studied in detail. Analysis in term of drag and diffusion contributions indicates a departure of the diffusion from the T-linear metallic behavior. This effect is increased in the strongly overdoped range (p~0.2-0.28) and should reflect the proximity of some topological change.Comment: 4 pages, 4 figure

Physico-chemical characterization of mixed-ligand complexes of Mn(III) based on the acetylacetonate and maleic acid and its hydroxylamine derivative

Two new Mn(III) mixed-ligand complexes with two acetylacetonate (acac) ligands and one maleate ligand and its hydroxylamine derivative of the general formula [Mn(C5H7O2)2L] were prepared. Their structure was established by using elemental analysis, FTIR and UV/VIS spectroscopic methods, as well as magnetic measurement. Replacement of the acetylacetonate ligand by the corresponding acid ligand has been confirmed in Mn(III) acetylacetonate. Based on the obtained experimental data and literature indications, structural formulae to these compounds were assigned