In situ biosynthesized silver nanoparticle-incorporated synthesized zeolite A using Orthosiphon aristatus extract for in vitro antibacterial wound healing

The capability of synthesized zeolite A (SZ) to immobilize Ag ions (Ag-SZ) and Ag nanoparticles (AgNp-SZ) were comparatively studied. A novel approach of in situ biosynthesized AgNP-incorporated synthesized zeolite A (AgNp-SZ) was synthesized at an optimum volume of 0.4 mL of the Orthosiphon aristatus (O. aristatus) leaves plant extract (5%) using an in situ approach. In comparison, Ag-SZ was produced by loading the synthesized zeolite with Ag ions. All synthesized materials were characterized for their morphologies and physicochemical properties. The characterization analyses validate that the biosynthesized AgNP (<100 nm) using O. aristatus leaves extract was incorporated into the zeolite A. The antibacterial testing confirmed that these materials have antibacterial activity against Escherichia coli ATCC 11229 and Staphylococcus aureus ATCC 6538. MIC/MBC analysis demonstrated that in 0.9% saline solution, AgNP-SZ had higher antibacterial activity than Ag-SZ. The in vitro cell viability and migration assays were further examined towards human skin fibroblast cells HSF 1184. Results show that the materials are not cytotoxic to HSF 1184, and the biosynthesized AgNP-SZ promotes cell migration and proliferation higher than Ag-SZ. This research proved that the biocompatible antibacterial wound healing agent of AgNP-SZ can be synthesized using an in situ approach where the reduction process of Ag ions in the zeolite A can be performed using plant extract.     

Capuli cherry-mediated green synthesis of silver nanoparticles under white solar and blue LED light

In this article, the Capuli (Prunus serotina Ehrh. var. Capuli) cherry extract was used for the synthesis of silver nanoparticles (AgNPs) in the presence of white/visible solar and blue light-emitting diode (LED) light. For the characterization of the extract and the AgNPs, Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy were employed, along with hydrodynamic particle size analysis, transmission electron microscopy and X-ray diffraction. The Ag nanospheres obtained using white light were 40–100 nm in diameter and exhibited an absorption peak at λ_max = 445 nm, whereas those obtained using blue LED light were 20–80 nm in diameter with an absorption peak at λ_max = 425 nm. Thermal analysis revealed that the content of biomolecules surrounding the AgNPs was about 55–65%, and it was also found that blue LED light AgNPs (56.28%, 0.05 mM) had a higher antioxidant efficacy than the white solar light AgNPs (33.42%, 0.05 mM) against 1,1-diphenyl-2-picrylhydrazyl. The results indicate that obtaining AgNPs using a blue LED light may prove to be a simple, cost-effective and easily reproducible method for creating future nanopharmaceuticals.     

Green synthesis,characterization and physiological stability of gold nanoparticles from Stachys lavandulifolia Vahl extract

The synthesis of nontoxic stable gold nanoparticles is important for medical applications. An aqueous extract of the plant Stachys lavandulifolia Vahl was used to synthesize gold nanoparticles. This green method involved the S. lavandulifolia Vahl extract acting as a reducing and stabilizing agent. The nanoparticles were characterized by transmission electron microscopy, dynamic light scattering analysis and UV–vis absorption and Fourier transform-infrared spectroscopies. Stability under physiological conditions is important for medical applications. The stability of the nanoparticles was compared with that of conventional citrate-capped nanoparticles, under both synthetic and physiological conditions. The nanoparticles synthesized from the S. lavandulifolia Vahl extract were stable under physiological conditions, in contrast with conventional citrate-capped nanoparticles.     

Ballistic electron transport in non-equilibrium warm dense gold

We have measured the time evolution of the phase shift at the front and back surfaces of gold nano-foils that have been excited with a 150 fs (λ = 400 nm) laser pulse. The thickness of the foils (d～30 nm) is roughly one-third of the ballistic electron transport range at ambient conditions (～100 nm). At lower pump fluences, the front and back sides of the foil behave similarly, indicating uniform heating by ballistic electrons. As the pump fluence is increased, the phase shift on the front side is higher than that on the back, indicating a significant reduction in the ballistic electron transport range.     

Fabrication of nano-sized Ca(OH)2 with excellent adsorption ability for N2O4

Uniform nano-sized calcium hydroxide (Ca(OH)₂) monocrystal powder was synthesized from calcium oxide in a surfactant solution via a digestion method by decreasing the surface tension of the reaction system to control the growth of crystalline Ca(OH)₂. The Ca(OH)₂ monocrystal powder samples were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and Fourier transform-infrared spectroscopy (FT-IR). The NO_x adsorption ability of the samples was evaluated, and the influence of various types and concentrations of surfactants on powder agglomeration and then the specific surface area in the precipitation process were studied. The specific surface area of the samples was found as high as 58 m²/g and 92 m²/g and the particle size, 300–400 nm and 200–300 nm in the presence of 10 wt% PEG600 and 0.086 mL/L SDS at a reaction time of 5 h, respectively. The product has an exceptionally strong adsorption ability for NO_x, which makes it a highly promising adsorbent for emission control and air purification.     

Solvent-less synthesis of zinc oxide nanostructures from Zn(salen) as precursor and their optical properties

ZnO nanoparticles, 10–20 nm in size, were synthesized by heat treatment in air at 500 °C for 5 h., using [N,N′-bis(salicylaldehydo) ethylene diamine]zinc(II), i.e., Zn(salen), as precursor, which was obtained by a solvent-free solid–solid reaction. Heat-treated products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Room temperature photoluminescence spectra of ZnO nanostructures are dominated by green emission attributed to oxygen vacancy related donor–acceptor transition.     

Visible light-driven photocatalysis of W,N co-doped TiO2

W, N co-doped TiO2 nanoparticles were synthesized by a sol-gel method. The prepared samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FE-SEM）, trans- mission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FT-1R）, X-ray photoelectron spectroscopy （XPS） and diffuse reflectance spectrophotometry （DRS）. The results showed that the co- doped photocatalysts were essentially uniform spherical particles with the smallest particle size of 22.5 nm. Compared to un-doped TiO2, N-TiO2 and P-25, the absorption edge of the W, N co-doped TiO2 shifted to longer wavelength and its photocatalytic activity for degradation of methyl orange （MO） under Xe-lamp （350W） was higher.     

Controlled growth of silver nanoparticles in a hydrothermal process

A two-step synthesis was used to control the shape of silver nanoparticles prepared via reduction of Ag^＋ ions in aqueous Ag（NH3）2NO3 by poly（N-vinyl-2 First, a few spherical silver nanoparticles,-10 nm in size, were pyrrolidone） （PVP）. Then, in a subsequent hydrothermal treatment, the remaining Ag^＋ ions were reduced by PVP into polyhedral nanoparticles, or larger spherical nanoparticles formed from the small spherical seed silver nanoparticles in the first step. The morphology and size of the resultant particles depend on the hydrothermal temperature, PVP/Ag molar ratio and concentration of Ag^＋ ions. By using UV-visible spectroscopy （UV-vis）, transmission electron microscopy （TEM） and powder X-ray diffraction （XRD）, the possible growth mechanism of the silver nanoparticles was discussed. 2007 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.     

Understanding the anomalous dispersion of doubly ionized carbon plasmas near 47 nm

Over the last several years we have predicted and observed plasmas with an index of refraction greater than 1 in the soft X-ray regime. These plasmas are usually a few times ionized and have ranged from low-Z carbon plasmas to mid-Z tin plasmas. Our main calculational tool has been the average-atom code. We have recently observed C²⁺ plasmas with an index of refraction greater than 1 at a wavelength of 46.9 nm (26.44 eV). In this paper we compare the average-atom method, AVATOMKG, against two more detailed methods, OPAL and CAK, for calculating the index of refraction for the carbon plasmas and discuss the different approximations used. We present experimental measurements of carbon plasmas that display this anomalous dispersion phenomenon. It is shown that the average-atom calculation is a good approximation when the strongest lines dominate the dispersion. However, when weaker lines make a significant contribution, the more detailed calculations such as OPAL and CAK are essential. During the next decade X-ray free electron lasers and other X-ray sources will be available to probe a wider variety of plasmas at higher densities and shorter wavelengths so understanding the index of refraction in plasmas will be even more essential. With the advent of tunable X-ray lasers the frequency-dependent interferometer measurements of the index of refraction may enable us to determine the absorption coefficients and lineshapes and make detailed comparisons against our atomic physics codes.     

Mixed-solvent thermal synthesis and magnetic properties of flower-like microstructured nickel

Flower-like microstructured nickel was synthesized by a facile mixed-solvent thermal process. The structure, morphology, and magnetic properties of the reaction products were investigated, respectively, by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The results showed that the products consisted of a face-centered cubic (fcc) structure with lattice constant of α = 3.524 Å. The average diameter of flower-like microstructured nickel was about 5 μm and the thickness of a single flake was about 100 nm. Magnetic measurement showed that these powders exhibited ferromagnetic characteristics.     

Fibrin network adaptation to cell-generated forces

Fibrin promotes wound healing by serving as provisional extracellular matrix for fibroblasts that realign and degrade fibrin fibers, and sense and respond to surrounding substrate in a mechanical-feedback loop. We aimed to study mechanical adaptation of fibrin networks due to cell-generated forces at the micron-scale. Fibroblasts were elongated-shaped in networks with ≤?2 mg/ml fibrinogen, or cobblestone-shaped with 3 mg/ml fibrinogen at 24 h. At frequencies f?<?10² Hz, G′ of fibroblast-seeded fibrin networks with ≥?1 mg/ml fibrinogen increased compared to that of fibrin networks. At frequencies f?>?10³ Hz, G″ of fibrin networks decreased with increasing concentration following the power-law in frequency with exponents ranging from 0.75?±?0.03 to 0.43?±?0.03 at 3 h, and of fibroblast-seeded fibrin networks with exponents ranging from 0.56?±?0.08 to 0.28?±?0.06. In conclusion, fibroblasts actively contributed to a change in viscoelastic properties of fibrin networks at the micron-scale, suggesting that the cells and fibrin network mechanically interact. This provides better understanding of, e.g., cellular migration in wound healing.

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Magnetic nanoparticles for environmental and biomedical applications: A review

Engineered magnetic nanoparticles (MNPs) hold great potential in environmental, biomedical, and clinical applications owing to their many unique properties. This contribution provides an overview of iron oxide MNPs used in environmental, biomedical, and clinical fields. The first part discusses the use of MNPs for environmental purposes, such as contaminant removal, remediation, and water treatment, with a focus on the use of zero-valent iron, magnetite (Fe₃O₄), and maghemite (γ-Fe₂O₃) nanoparticles, either alone or incorporated onto membrane materials. The second part of this review elaborates on the use of MNPs in the biomedical and clinical fields with particular attention to the application of superparamagnetic iron oxide nanoparticles (SPIONs), which have gained research focus recently owing to their many desirable features such as biocompatibility, biodegradability, ease of synthesis and absence of hysteresis. The properties of MNPs and their ability to work at both cellular and molecular levels have allowed their application in vitro and in vivo including drug delivery, hyperthermia treatment, radio-therapeutics, gene delivery, and biotherapeutics. Physiochemical properties such as size, shape, and surface and magnetic properties as well as agglomeration of MNPs and methods to enhance their stability are also discussed.     

Efficient methods for calculating the number of states,levels and lines in atomic configurations

Exact or statistical methods for determining the distribution of the M_J values (projection of total angular momentum J) in an electron configuration are presented. This distribution, noted P(M_J), is used to calculate the allowed values of J and the number of electric-dipolar (E1) lines between two configurations. First, the difficulty to account for the Pauli exclusion principle for equivalent electrons is stressed. Showing the limit of the usual exact approach, a very efficient recursive technique is proposed for determining exactly the distribution P(M_J). Second, the statistical approach of Bauche and Bauche-Arnoult [J. Phys. B Atom. Mol. Opt. Phys. 20 (1987) 1659] is extended in order to account for configurations with a high-? spectator. In this case, identical consecutive values may exist in the center of P(M_J), which can neither be modeled by a Gaussian nor by a Gram–Charlier type function. It is shown that the Generalized Gaussian function, with the exponent constrained by the kurtosis (reduced fourth-order centered moment) of P(M_J), is more suited in these situations. A new analytical formula for the evaluation of the number of E1 lines with a larger range of applicability is then proposed.     

Novel synthesis with an atomized microemulsion technique and characterization of nano-calcium carbonate （CaCO3）/poly（methyl methacrylate） core-shell nanoparticles

The synthesis of hard-core/soft-shell calcium carbonate （CaCO3）/poly（methyl methacrylate） （PMMA） hybrid structured nanoparticles （〈100nm） by an atomized microemulsion polymerization process is reported. The polymer chains were anchored onto the surface of nano-CaCO3 through use of a cou- pling agent, triethoxyvinyl silane （TEVS）. Ammonium persulfate （APS）, sodium dodecyl sulfate （SDS） and n-pentanol were used as the initiator, surfactant and cosurfactant, respectively. The polymeriza- tion mechanism of the core-shell latex particles is discussed. The encapsulation of nano-CaCO3 by PMMA was confirmed using a transmission electron microscope （TEM）. The grafting percentage of the core-shell particles was investigated by thermogravimetric analysis （TGA）. The nano-CaCO3/PMMA core-shell par- ticles were characterized by Fourier transform infrared （FTIR） spectroscopy and differential scanning calorimetry （DSC）. The FTIR results revealed the existence of a strong interaction at the interface of the nano-CaCO3 particle and the PMMA, which implies that the polymer chains were successfully grafted onto the surface of the nano-CaCO3 particles through the link of the coupling agent, In addition, the TGA and DSC results indicated an enhancement of the thermal stability of the core-shell materials compared with that of the pure nano-PMMA, The nano-CaCO3/PMMA particles were blended into a polypropylene （PP） matrix by melt processing. It can also be observed using scanning electron microscopy （SEM） that the PMMA chains grafted onto the CaCO3 nanoparticles interfere with the aggregation of CaCO3 in the polymer matrix （PP matrix） and thus improve the compatibility of the CaCO3 nanoparticles with the PP matrix.     

Spatiotemporal representation of the dynamic modes in turbulent cavity flows

Proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) were used to extract the coherent structures in turbulent cavity flows. The spatiotemporal representation of the modes was achieved by performing the circular convolution of a change of basis on the data sequence, wherein the transformation function was extracted from the POD or DMD. The spatiotemporal representation of the modes provided significant insight into the evolutionary behavior of the structures. Self-sustained oscillations arise in turbulent cavity flows due to unsteady separation at the leading edge. The turbulent cavity flow at Re_D = 12,000 and a length to depth ratio L/D = 2 was analyzed. The dynamic modes extracted from the data clarified the presence of self-sustained oscillations. The spatiotemporal representation of the POD and DMD modes that caused self-sustained oscillations revealed the prevalent dynamics and evolutionary behavior of the coherent structures from their formation at the leading edge to their impingement at the trailing edge. A local minimum in the mode amplitude representing the energy contributions to the flow was observed upon the impingement of coherent structure at the trailing edge. The modal energy associated with the periodic formation of organized coherent structures followed by their dissipation upon impingement revealed the oscillatory behavior over time.     

Transmission electron microscopy investigation of dislocation slip during superelastic cycling of Ni-Ti wires

Superelastic deformation of thin Ni-Ti wires containing various nanograined microstructures was investigated by tensile cyclic loading with in situ evaluation of electric resistivity. Defects created by the superelastic cycling in these wires were analyzed by transmission electron microscopy. The role of dislocation slip in superelastic deformation is discussed. Ni-Ti wires having finest microstructures (grain diameter <100 nm) are highly resistant against dislocation slip, while those with fully recrystallized microstructure and grain size exceeding 200 nm are prone to dislocation slip. The density of the observed dislocation defects increases significantly with increasing grain size. The upper plateau stress of the superelastic stress-strain curves is largely grain size independent from 10 up to 1000 nm. It is hence claimed that the Hall-Petch relationship fails for the stress-induced martensitic transformation in this grain size range. It is proposed that dislocation slip taking place during superelastic cycling is responsible for the accumulated irreversible strains, cyclic instability and degradation of functional properties. No residual martensite phase was found in the microstructures of superelastically cycled wires by TEM and results of the in situ electric resistance measurements during straining also indirectly suggest that none or very little martensite phase remains in the studied cycled superelastic wires after unloading. The accumulation of dislocation defects, however, does not prevent the superelasticity. It only affects the shape of the stress-strain response, makes it unstable upon cycling and changes the deformation mode from localized to homogeneous. The activity of dislocation slip during superelastic deformation of Ni-Ti increases with increasing test temperature and ultimately destroys the superelasticity as the plateau stress approaches the yield stress for slip. Deformation twins in the austenite phase ({1 1 4} compound twins) were frequently found in cycled wires having largest grain size. It is proposed that they formed in the highly deformed B19′ martensite phase during forward loading and are retained in austenite after unloading. Such twinning would represent an additional deformation mechanism of Ni-Ti yielding residual irrecoverable strains.     

Turbulent time-events in channel with rough walls

This brief communication quantifies the time-events that contribute to the dynamics of wall-bounded flows with rough walls. Lumley’s Proper Orthogonal Decomposition (POD) methodology has been used to extract the energetic modes of the flow. We have used the concept of entropy, a representation of lack of organization in the flow, to represent the extent of spread of turbulent kinetic energy to higher modes. The rough-wall dynamics is dominated by fast activity (short time period) propagating modes and slow activity (long time period) roll modes. A single dominant timescale has been captured for all the propagating modes in flows over smooth walls; multiple dominant timescales representing various vortex shedding events are captured for rough walls. Variable-interval time averaging technique has been used to obtain the bursting frequency. The bursting frequency of rough-wall turbulence is higher compared to smooth-wall turbulence, suggesting that roughness enhances turbulence production activity. Another insightful observation for rough walls revealed by our study is that the vortex shedding frequency of roughness elements is much higher compared to the bursting frequency of rough-wall turbulence. POD provides a straightforward method to extract the natural frequency of shed vortices due to roughness, an important dynamical activity in rough-wall turbulent boundary layers.     

Size-dependent cellular uptake and sustained drug release of PLGA particles

Poly (lactic-co-glycolic) acid (PLGA) particles have become a commonly used drug delivery strategy in the pharmaceutical industry. In this work, we aim to investigate the size-dependent cellular internalization of PLGA particles and its effects on sustained drug release. We prepared three different-sized particles using PLGA (200, 500 and 2000 nm) ranging from submicrometer to micrometer. Dexamethasone (DEX) with excellent anti-inflammatory properties was used as a model drug to prepare DEX-loaded PLGA particles (DPs). We comprehensively investigated the encapsulation efficiency, cellular uptake and in vitro drug release profile. Pharmacodynamic assessment revealed that, in the lipopolysaccharide (LPS)-induced RAW 264.7 cells model, 500 nm DPs showed sustained anti-inflammatory efficacy. This work provides important information for designing PLGA-based drug delivery systems for biomedical applications.     

Magnetic and electrochemical behavior of rhombohedral α-Fe2O3 nanoparticles with (1 0 4) dominant facets

Uniform rhombohedral α-Fe₂O₃ nanoparticles, ～60 nm in size, were synthesized via a triphenylphosphine-assisted hydrothermal method. Scanning electron micrograph (SEM) and transmission electron micrograph (TEM) analyses showed that the as-synthesized rhombohedral nanoparticles were enclosed by six (1 0 4) planes. The concentration of triphenylphosphine played an important role in morphological evolution of the α-Fe₂O₃ nanoparticles. The as-prepared rhombohedral nanoparticles possessed remanent magnetization M_r of 2.6 × 10^?3 emu/g and coercivity H_C of 2.05 Oe, both lower than those of other α-Fe₂O₃ particles with similar size, indicating their potential applications as superparamagnetic precursor materials. Furthermore, these rhombohedral α-Fe₂O₃ nanoparticles exhibited good sensor capability toward H₂O₂ with a linear response in the concentration range of 2–20 mM.     

Thermodynamics of the quasi-static growth of Griffith cracks

Restrictions on the quasi-static extension, or healing, of Griffith cracks are developed in the framework of irreversible thermodynamics. It is emphasized that thermodynamics requires that (G ? 2γ)ι ? 0, where ι is crack speed, G the Irwin energy release rate, and 2γ the work of reversible separation of the surfaces to be fractured. Implications for ‘lattice trapping’ models of cracks and for thermally-activated crack motion are discussed, as are the effects on crack growth and healing of a surface-reactive environment, in which case γ must be given a definition appropriate to adsorption-altered surface properties.