Structural Studies in Search for New Materials for ‘Green’ Economy

tekst w j. pol. i ang.Samowystarczalna energetycznie gospodarka wymaga szeregu zmian technologicznych w procesie wytwarzania energii i jej składowania. Podniesienie efektywności poszczególnych etapów możliwe jest dzięki lepszemu zrozumieniu podstaw fizycznych stojących za pożądanymi własnościami materii

Power spectrum, growth velocities and cross-correlations of longitudinal and transverse oscillations of individual Nicotiana tabacum pollen tube

We report on our results concerning growth rate and oscillation modes of the individual pollen tube apex. The observed volumetric growth and growth rate periodicity in the longitudinal (axial) direction are accompanied by transverse oscillations with similar frequencies but higher energies than the axial modes. Examination of the time-domain coherence between oscillations in mutually perpendicular directions revealed minimal energy dissipation in the unperturbed (isotonic) case, opposite to the two remaining cases (hypertonic, hypotonic) with notable correlations. We conjecture that the minimal energy loss is therefore optimal in the natural growth conditions. The longitudinal growth velocity is also found to be the fastest in the unperturbed case. As a result, the isolated system (pollen tube tip) is conserving energy by transforming it from elastic potential energy of extending apical wall to the kinetic energy of periodical motion. The energy dissipation is found to be about 20 % smaller in axial direction than in lateral one, indicating that the main energy consumption is dedicated to the elongation. We further observe that the hypertonic spectrum is shifted towards lower and the hypotonic towards higher frequencies with respect to the isotonic spectrum. In consequence, the turgor pressure inside the growing cell influences monotonically the frequency of both modes of oscillations. The calculated power spectrum seen as a measure of the overall energy efficiency of tip growth under hypertonic, hypotonic and isotonic conditions implies that the biochemistry has been fine tuned to be optimal under normal growth conditions, which is the developmental implication of this work. A simple theoretical extension of the Ortega equation is derived and analysed with respect to its contribution to power spectrum. We show that the plastic term, related to the effective turgor pressure, with maximum contribution at frequency f = 0 is responsible for the steady growth. In turn, the elastic contribution dependent on the time derivative of pressure fluctuations tends to move the system into oscillatory mode (f > 0). None of those mechanisms is privileged over another. The coupling mechanism is naturally generated through a convolution of those two terms and will decide about the overall character of the growth for each particular case

Application of the effective formula of growth functional to quantitative description of growth of plant cells

An effective formula describing expansive plant growth is derived from the modified Lockhart/Ortega-type equation. Its applicability is demonstrated on selected experimental data extracted from available literature. Quantitative information about the “diffusion rate” (k 2) of the growth factors is obtained for two different model species in plant science: Arabidopsis thaliana L. belongs to the dicots and Zea mays L. belongs to the monocots. It is shown that the value of the diffusion rate may be useful in comparing different datasets and serve as a measure of reproducibility of standard measurements. Analysis of the formula and fits allows to identify and suggest a set of criteria for reporting future experiments, which would improve comparability and reproducibility of the results

Determination and characterization of selected fluoroquinolones oxidation products under potassium permanganate treatment

A simple, sensitive and reproducible ultra-performance liquid chromatography (UPLC) method for the determination of: danofloxacin, enrofloxacin, marbofloxacin, orbifloxacin and pefloxacin oxidation stability under permanganate treatment in acidic conditions at pH from 3.0 to 6.0, was developed. Chromatographic separations were carried out using the Acquity UPLC BEH C 1 8 column; (2.1 x 100 mm, 1.7 pm particle size). The column was maintained at 40OC, and eluted under gradient conditions using from 100% to 75% of eluent A over 10 min for danofloxacin, enrofloxacin, marbofloxacin, orbifloxacin or 95% to 75% of eluent A over 10 min for pefloxacin, at a flow rate of 0.3 mL/min. Eluent A: 1% (v/v) formic acid in water; eluent B: 0.1% (v/v) formic acid in acetonitrile. Satisfactory resolution was obtained for oxidation products. The correlation coefficients and determination coefficients (R2) obtained for linear model for all examined fluoroquinolones were greater than 0.99. Linearity range was observed in the concentration range 0.06-0.13 mg/mL. Sensitivity of the method was good. The LOD and LOQ values were found to be 0.01 mg/mL and from 0.02 to 0.04 mg/mL, respectively. Good precision and intermediate precision with %RSD less than 2.0% was observed. The oxidation processes followed kinetic of the second order reaction and depended upon solution acidity. Oxidation of fluoroquinolones proceeded at piperazine moiety yielding respective hydroxy and oxo analogs, and leaving the quinolone fragment intact. Structures of products formed were assigned on a basis of UPLC/MS/MS fragmentation pathways

Preliminary safety assessment of new azinesulfonamide analogs of aripiprazole using prokaryotic models

Purpose: Determination of the mutagenic potential of new biologically active compounds is of great concern for preliminary toxicity testing and drug development. Methods: The mutagenic and antimutagenic effects of some quinoline- and isoquinoline-sulfonamide analogs of aripiprazole (1-8), which display potent antidepressant, anxiolytic, and antipsychotic properties, were evaluated using the Vibrio harveyi assay and OSIRIS Property Explorer software. Additionally, the Ames test was used as the reference. Results: In silico prediction showed that compounds 5 (N-(3-(4-(2,3-dichlorophenyl)piperazin-1-yl)propyl)quinoline-7-sulfonamide) and 6 (N-(4-(4-(2,3-Dichlorophenyl)piperazin-1-yl)butyl)quinoline-7-sulfonamide) trigger a mutagenic structural alert. However, this was not confirmed by in vitro assays, as none of the tested compounds displayed mutagenic activity against all tested strains of bacteria. Moreover, compounds 1-8 displayed a protective effect against the mutagenicity induced by a direct acting mutagen NQNO. The most beneficial antimutagenic properties showed compound 5 which exhibited strong antimutagenic properties in all tested V. harveyi strains. High antimutagenic potency of this compound was confirmed in the Ames TA100 assay system. Conclusion: Newly synthesized azinesulfonamide analogs of aripiprazole may be considered as genotoxically safe as they do not display mutagenic activity on the tester strains. Moreover, the tested compounds demonstrated significant antimutagenic properties that can be valuable for prevention of the NQNO genotoxicity. Additionally, it appears that the Vibrio harveyi assay can be applied for primary mutagenicity and antimutagenicity assessment of chemical substances, thus, representing a useful alternative tool for compounds safety evaluation

Application of X-ray powder diffraction and differential scanning calorimetry for identification of counterfeit drugs

X-ray analysis confirmed that in all investigated samples, the active API (acetylsalicylic acid and ascorbic acid) was present. The values of the interplanar distance dhkl for the studied samples are in good accordance with those presented in the ICDD database. The intensities of the diffraction lines depend on the content of the component in the tested preparation. Therefore, different intensities of lines for the APIs were observed in the obtained diffraction patterns. Thermal analysis of the studied substances showed that during the thermal analysis, the following phenomena might occur: dehydration and (or) melting, crystalline transformation. Moreover, it was found that the chemical structure of the studied compounds affects the process of their thermal decomposition. The data obtained during these investigations can be useful in quick tests of physicochemical discrepancies and abnormalities between potential components of pharmaceutical preparations. The evidence for the interaction can be obtained by comparing DSC and TG curves of the drug and the excipient, as well as those of their physical mixtures. For this reason, the study of characteristics of thermal decomposition of drugs and excipients is necessary. Based on the above investigations, it may be stated that a combination of two methods: XRPD and DSC can be used to distinguish the original drugs from counterfeit products, e.g., by checking for the presence of the correct API or by a comparison of the drugs fingerprint

Tuning the magnetocaloric response of Gd7-xYxPd3 (2 ≤ x ≤ 6) alloys by microstructural modifications

We investigated the influence of microstructural changes on the magnetic properties and the magnetocaloric response of the Gd7-xYxPd3 (2 ≤ x ≤ 6) alloys rapidly quenched by vacuum suction casting (rc-cast samples) and melt-spinning (melt-spun samples) techniques. Quenched-in structural disorder determines magnetic and magnetocaloric properties in both series of alloys. For the rc-cast samples two distinct magnetic transitions are visible. The peak at higher temperatures is related to the ferromagnetic/paramagnetic transition of the crystalline phase. In contrast, the peak observed at low temperatures is believed to be related to the ferro-para transition of the amorphous phase and/or a spin reorientation. The Gd7-xYxPd3 alloys in the form of rapidly cooled cast exhibit the magnetic transition temperatures at 262 K, 242 K, 202 K, 153 K and 9 K, for 2 ≤ x ≤ 6 respectively. Curie temperatures of the melt-spun Gd7-xYxPd3 alloys are much lower compared to the rc-cast samples. The melt-spun Gd5Y2Pd3 orders ferromagnetically below 90 K, while Gd4Y3Pd3, Gd3Y4Pd3, Gd2Y5Pd3 and GdY6Pd3 ribbons undergo the magnetic transformation at 65 K, 40 K, 25 K, and 9 K, respectively. Investigated ribbons exhibit almost doubled magnetic entropy change in comparison to the rc-cast samples. For instance, the -ΔSm value for melt-spun and rc-cast Gd5Y2Pd3 is equal to 6.31 Jkg-1K-1 and 3.64 Jkg-1K-1, respectively. Moreover, due to the large δTFWHM of the magnetic entropy change peak, both the melt-spun and rc-cast samples exhibit large relative cooling power (RCP), reaching 466 Jkg-1 (Δμ0H = 5 T) for the rc-cast Gd5Y2Pd3. RCP values are comparable to those of some potential magnetic refrigerants

The Mossbauer spectroscopy and analytical investigations of the polycrystaline compounds with general formula ZnxSnyCr2Se4

We present combined X-ray powder diffraction and Mossbauer 119Sn studies of polycrystalline compounds with a general formula ZnxSnyCrzSe4 (where x + y + z ¼ 3). The obtained single-phase compounds crystallize in the spinel cubic structure | Fd3m. Tin ions are found to occupy both tetrahedral and octahedral sublattices. On the contrary to the strong tetrahedral site preference energy of Sn, the presented data strongly suggest that the increase in lattice parameters with Sn doping is caused by Sn ions that incorporated into octahedral positions. A quadrupole and isomer shifts of 119Sn in (SnSe4)6¡ and (SnSe6)4¡ are also reported