On Bhattacharyya relative entropy in a homogenization of composite materials

The main idea of this work is an application of relative entropy in the numerical analysis of probabilistic divergence between original material tensors of the composite constituents and its effective tensor in the presence of material uncertainties. The homogenization method is based upon the deformation energy of the representative volume elements for the fiber-reinforced and particulate composites and uncertainty propagation begins with elastic moduli of the fibers, particles, and composite matrices. Relative entropy follows a mathematical model originating from Bhattacharyya probabilistic divergence and has been applied here for Gaussian distributions. The semi-analytical probabilistic method based on analytical integration of polynomial bases obtained via the least squares method fittings enables for determination of the basic probabilistic characteristics of the effective tensor and the relative entropies. The methodology invented in this work may be extended toward other probability distributions and relative entropies, for homogenization of nonlinear composites and also accounting for some structural interface defects.     

Understanding the Photothermal and Photocatalytic Mechanism of Polydopamine Coated Gold Nanorods

Localized surface plasmon resonance (LSPRs) shown by gold nanorods (AuNRs) has several applications in photocatalysis, sensing, and biomedicine. The combination of AuNRs with Polydopamine (PDA) shells results in a strong photo-thermal effect, making them appealing nanomaterials for biomedical applications. However, the precise roles and relative contributions of plasmonic effects in gold, and light-to-heat conversion in PDA are still debated. Herein, a hybrid nanoplatform made by an AuNR core surrounded by a polydopamine (PDA) shell is synthesized, and its photocatalytic behavior is studied. Synthesis is based on a seed-mediated growth followed by the further self-polymerization of dopamine hydrochloride (DA) on the surface of the AuNRs, and the effect of the thickness of the PDA shell on the plasmon response of the composite is the main examined parameter. Photocatalytic performance is tested toward Rhodamine 6G (Rh6G), with the nanocomposites achieving better performance than bare AuNRs and bare PDA nanoparticles. The degradation of 54% of Rh6G initial concentration is achieved within 60 min of irradiation with a catalyst concentration of 7.4 µg mL⁻¹. Photodegradation kinetics, time-resolved spectroscopy, and finite-element-method simulations of plasmons show that AuNRs plasmons, coupled with the low thermal conductivity of PDA, provide slow thermalization, while enhancing the charge carrier transfer.     

Giant Pressure-Induced Spectral Shift in Cyan-Emitting Eu2+-Activated Sr8Si4O12Cl8 Microspheres for Ultrasensitive Visual Manometry

To address the unsatisfactory pressure sensitivity of luminescent manometers, Eu²⁺-activated supersensitive microspheres operating in the visible range are developed. A series of Eu²⁺-doped Sr₈Si₄O₁₂C_l8 materials are synthesized as microspheres, and their structural and spectroscopic properties are studied theoretically and experimentally. Excited at 350 nm, the samples emit a bright cyan luminescence at ambient conditions that, upon pressure, changes to green emission and finally to yellow light above 7 GPa. Most importantly, a huge red-shift of the emission band from 497.3 to 568.8 nm is observed as the pressure increases, leading to an ultrahigh-pressure sensitivity of 9.69 nm/GPa, which is the highest sensitivity ever reported. The designed microspheres with polychromatic emissions and high-pressure sensitivity are suitable for visual optical pressure sensing, and the applied strategy provides some important guidelines for the development of new optical manometers, allowing pressure monitoring with unprecedented accuracy.     

Microwave‐Assisted Oxidation of Side Chain Arenes by MagtrieveTM

A commercial tetravalent chromium dioxide (Magtrieve^TM) as a magnetically retrievable oxidant is shown to be a very useful compound for microwave‐assisted and conventional transformation of aromatic and alkyl aromatic molecules into the corresponding aryl ketones, quinones or lactones.     

Application of Phytotests to Study of Environmental Safety of Biologicaly Synthetised Au and Au/ZnO Nanoparticles Using Tanacetum parthenium Extract

Due to their small sizes and high reactivity, nanoparticles have a completely different toxicity profile than larger particles, and it is difficult to predict their potential ecological impact. There is a need for broad ecotoxicological studies of nanomaterials in order to specify their environmental impact and ensure safe application of nanotechnology products. In this work, we have assessed the toxicity of Au and Au/ZnO metal nanoparticles obtained with the use of Tanacetum parthenium (herba) extract. The obtained nanoparticles were characterized by UV–Vis spectrophotometry (UV–VIS), Transmission electron microscopy (TEM), Atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). In order to assess the toxicity of biologically synthesized nanoparticles, we used seeds of various plants: Lepidium sativum, Linum flavum, Zea mays, Salvia hispanica-chia, Lupinus angustifolius, Petroselinum crispum subsp. Crispum, Beta vulgaris, Phaseolus vulgaris. The in vitro phytotests showed that gold nanoparticles at a specific range of concentrations for all plants stimulated their growth. The highest growth activity was exhibited by the solution at the concentration of 0.300 mg/ml towards corn (Aw ≈ ??135?±?16) and flax (Aw ≈ ??44?±?10). Only for parsley the IC50 was determined at 0.57 mg/ml, but solutions at the concentration of 0.030 to 0.150 mg/ml also stimulated plant growth. Au/ZnO had a toxic effect at all concentrations applied in the study.

     

A Novel Strategy as a Potential Rapid Therapy Modality in the Treatment of Corneal Ulcers: Fluconazole/Vancomycin Dual Drug-Loaded Nanofibrous Patches

Corneal ulcer, which is brought on by a breach in the epithelial barrier, is a dangerous infection of the avascular corneal stroma. New treatment strategies are needed, suppressing the aggressive nature of the disease and including a combination of different drugs. In this study, vancomycin (VAN) and fluconazole (FLU) dual-drug loaded dual-layered polyvinyl alcohol and gelatin (PVA/GEL) nanofibrous patches are produced by electrospinning. Scanning electron microscopy (SEM) images show smooth surfaces are obtained for both pure and drug-loaded nanofibrous patches. The tensile test results report that loading the FLU and VAN separately into the PVA/GEL patches decrease both the tensile strength and elongation at break and it is further reduced when combining two drug-loaded layers in one patch. According to drug release results, the FLU and VAN-loaded nanofibrous patches show a controlled release profile extending up to 96 h. Moreover, PVA/GEL/FLU, PVA/GEL/VAN, and PVA/GEL/FLU/VAN nanofibrous patches display significant antimicrobial activity against Candida albicans and Staphylococcus aureus. SEM, 4'-6diamidynofenyloindol (DAPI) staining, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay show that PVA/FLU and PVA/GEL/FLU/VAN nanofibrous patches have a superior effect on NIH3T3 cell spreading and proliferation. The novelty of this study lays in the development of a potential dual drug rapid treatment for corneal ulcers of aggressive nature.