On the ν-dimensional one-component classical plasma: The thermodynamic limit problem revisited

We prove theH-stability property and the existence of the thermodynamic limit of the free energy density of the two-dimensional, one-component classical plasma. We give lower and upper bounds on the free energy density in any dimensionv and draw some consequences.     

Acid–Base Equilibrium and Self-Association in Relation to High Antitumor Activity of Selected Unsymmetrical Bisacridines Established by Extensive Chemometric Analysis

Unsymmetrical bisacridines (UAs) represent a novel class of anticancer agents previously synthesized by our group. Our recent studies have demonstrated their high antitumor potential against multiple cancer cell lines and human tumor xenografts in nude mice. At the cellular level, these compounds affected 3D cancer spheroid growth and their cellular uptake was selectively modulated by quantum dots. UAs were shown to undergo metabolic transformations in vitro and in tumor cells. However, the physicochemical properties of UAs, which could possibly affect their interactions with molecular targets, remain unknown. Therefore, we selected four highly active UAs for the assessment of physicochemical parameters under various pH conditions. We determined the compounds’ pK_a dissociation constants as well as their potential to self-associate. Both parameters were determined by detailed and complex chemometric analysis of UV-Vis spectra supported by nuclear magnetic resonance (NMR) spectroscopy. The obtained results indicate that general molecular properties of UAs in aqueous media, including their protonation state, self-association ratio, and solubility, are strongly pH-dependent, particularly in the physiological pH range of 6 to 8. In conclusion, we describe the detailed physicochemical characteristics of UAs, which might contribute to their selectivity towards tumour cells as opposed to their effect on normal cells.     

Exploration of the Crystal Structure and Thermal and Spectroscopic Properties of Monoclinic Praseodymium Sulfate Pr2(SO4)3

Praseodymium sulfate was obtained by the precipitation method and the crystal structure was determined by Rietveld analysis. Pr₂(SO₄)₃ is crystallized in the monoclinic structure, space group C2/c, with cell parameters a = 21.6052 (4), b = 6.7237 (1) and c = 6.9777 (1) Å, β = 107.9148 (7)°, Z = 4, V = 964.48 (3) ų (T = 150 °C). The thermal expansion of Pr₂(SO₄)₃ is strongly anisotropic. As was obtained by XRD measurements, all cell parameters are increased on heating. However, due to a strong increase of the monoclinic angle β, there is a direction of negative thermal expansion. In the argon atmosphere, Pr₂(SO₄)₃ is stable in the temperature range of T = 30–870 °C. The kinetics of the thermal decomposition process of praseodymium sulfate octahydrate Pr₂(SO₄)₃·8H₂O was studied as well. The vibrational properties of Pr₂(SO₄)₃ were examined by Raman and Fourier-transform infrared absorption spectroscopy methods. The band gap structure of Pr₂(SO₄)₃ was evaluated by ab initio calculations, and it was found that the valence band top is dominated by the p electrons of oxygen ions, while the conduction band bottom is formed by the d electrons of Pr³⁺ ions. The exact position of ZPL is determined via PL and PLE spectra at 77 K to be at 481 nm, and that enabled a correct assignment of luminescent bands. The maximum luminescent band in Pr₂(SO₄)₃ belongs to the ³P₀ → ³F₂ transition at 640 nm.     

Novel C60 Fullerenol-Gentamicin Conjugate–Physicochemical Characterization and Evaluation of Antibacterial and Cytotoxic Properties

This study aimed to develop, characterize, and evaluate antibacterial and cytotoxic properties of novel fullerene derivative composed of C₆₀ fullerenol and standard aminoglycoside antibiotic–gentamicin (C₆₀ fullerenol-gentamicin conjugate). The successful introduction of gentamicin to fullerenol was confirmed by X-ray photoelectron spectroscopy which together with thermogravimetric and spectroscopic analysis revealing the formula of the composition as C₆₀(OH)₁₂(GLYMO)₁₁(Gentamicin)_0.8. The dynamic light scattering (DLS) revealed that conjugate possessed ability to form agglomerates in water (size around 115 nm), while Zeta potential measurements demonstrated that such agglomerates possessed neutral character. In vitro biological assays indicated that obtained C₆₀ fullerenol-gentamicin conjugate possessed the same antibacterial activity as standard gentamicin against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli, which proves that combination of fullerenol with gentamicin does not cause the loss of antibacterial activity of antibiotic. Moreover, cytotoxicity assessment demonstrated that obtained fullerenol-gentamicin derivative did not decrease viability of normal human fibroblasts (model eukaryotic cells) compared to control fibroblasts. Thus, taking into account all of the results, it can be stated that this research presents effective method to fabricate C₆₀ fullerenol-gentamicin conjugate and proves that such derivative possesses desired antibacterial properties without unfavorable cytotoxic effects towards eukaryotic cells in vitro. These promising preliminary results indicate that obtained C₆₀ fullerenol-gentamicin conjugate could have biomedical potential. It may be presumed that obtained fullerenol may be used as an effective carrier for antibiotic, and developed fullerenol-gentamicin conjugate may be apply locally (i.e., at the wound site). Moreover, in future we will evaluate possibility of its applications in inter alia tissue engineering, namely as a component of wound dressings and implantable biomaterials.     

d2,8电子体系共价效应对光谱的影响

在含过渡金属离子的半磁半导体的光学和磁学性质研究中,由于体系的共价性较强,d轨道不再是纯d轨道,而是混合轨道t2g或eg。相应地,需要引入两个共价因子Nt和Ne。建立在混合轨道上的含有共价因子的能量矩阵称为广义能量矩阵。建立了d2,8电子体系的(45×45)阶广义能量矩阵。在广义能量矩阵中,拉卡(Racah)参量A不再是相加常量,同时,d8电子体系不能简单地视为互补的d2空穴体系,因为它们的能量矩阵形式不同。Nt和Ne虽然是属于两个不同轨道的不同的共价因子,但在数值上不能有大的差别,因为考虑进共价效应后,拉卡静电参量A对能级计算有极大的影响。这意味着在通常的光谱拟合中所采用的BCΔ方案是好的近似。以上结论被应用于ZnS∶Ni2 的d-d跃迁谱,计算结果与实验符合。     

Foaming and Structural Studies on the Acidic Subunit of Amaranth 11S Globulin Modified with Antihypertensive Peptides as a Function of pH and Ionic Strength

Some studies aimed at revealing the relationship between protein structure and their functional properties. However, the majority of these reports have been carried out using protein isolates. There are limited reports on the possible relationship between the functional properties and the structure of a purified protein. In this work the amaranth 11S globulin acidic subunit (AAC) and five mutations of the same protein that were modified in their variable regions with antihypertensive peptides (VYVYVYVY and RIPP), were analyzed at two ionic strength (2.9 and 17.6 g/L NaCl) and pH (3.0–7.0). Results revealed better solubility for the proteins mutated at the terminal ends (AACM.1 and AACM.4) and lower solubility for the protein inserted with RIPP peptide. Spectroscopy studies revealed an increase of β-sheet structure at high salt concentration for all proteins. It was also observed that salt concentration acted as a modulator, which allowed a better foam features for all modified proteins limiting movement of side chains and reducing red-shifted displacement of λmax. All proteins showed foam capacity ranging from 76 to 93% although foam stability was twofold better for modified proteins than for AAC at high salt concentration. This study allowed better understanding about the structural changes that influence the foaming properties of engineered proteins.     

Low-Molecular Pyrazine-Based DNA Binders: Physicochemical and Antimicrobial Properties

Pyrazine and its derivatives are a large group of compounds that exhibit broad biological activity, the changes of which can be easily detected by a substituent effect or a change in the functional group. The present studies combined theoretical research with the density functional theory (DFT) approach (B3LYP/6-311+G**) and experimental (potentiometric and spectrophotometric) analysis for a thorough understanding of the structure of chlorohydrazinopyrazine, its physicochemical and cytotoxic properties, and the site and nature of interaction with DNA. The obtained results indicated that 2-chloro-3-hydrazinopyrazine (2Cl3HP) displayed the highest affinity to DNA. Cytotoxicity studies revealed that the compound did not exhibit toxicity toward human dermal keratinocytes, which supported the potential application of 2Cl3HP in clinical use. The study also attempted to establish the possible equilibria occurring in the aqueous solution and, using both theoretical and experimental methods, clearly showed the hydrophilic nature of the compound. The experimental and theoretical results of the study confirmed the quality of the compound, as well as the appropriateness of the selected set of methods for similar research.     

Eu3+掺杂硼酸盐玻璃的光谱性质研究

测试了不同浓度掺杂下Eu^3＋离子在硼酸盐玻璃的吸收光谱、激发光谱与发射光谱,根据荧光光谱计算了各样品的强度参数力2与／24,分析了Eu^3＋离子掺杂浓度对其发光强度的影响．研究结果表明：在Eu^3＋离子高掺杂浓度时,会发生浓度猝灭效应,但由于Eu^3＋激活离子之间能量传递几率很小,使得Eu^3＋离子猝灭浓度较高。     

前驱体法制备氮氧化硅纳米线及其光学性能研究

在Ni催化剂的存在下,通过SiCl4的水解氨解反应并在1300℃氨气气氛中进行热氮化处理制得了无定形氮氧化硅纳米线.产物经X射线衍射(XRD)、热重-差示扫描量热(TG-DSC)、扫描电镜(SEM)、透射电镜(TEM)、能量色散谱(EDS)和选区电子衍射(SAED)等表征手段进行分析,结果表明纳米线为无定形结构,直径为100～150nm.在波长为220nm的光激发下,产物的光致发光光谱(PL)在563nm和289nm处分别出现了一个强的绿光发光峰和一个弱的紫光发光峰.对纳米线的生长机理进行分析,表明纳米线的生长遵循气-液-固(VLS)机制控制模式.