Resistant starch type 2 from lotus stem: Ultrasonic effect on physical and nutraceutical properties

Resistant starch type 2 (RS) was isolated from lotus stem using enzymatic digestion method. The isolated RS was subjected to ultrasonication (US) at different sonication power (100–400 W). The US treated and untreated RS samples were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), light microscopy and Fourier transform infrared spectroscopy (FT-IR). DLS revealed that particle size of RS decreased from 12.80 µm to 413.19 nm and zeta potential increased from −12.34 mV to −26.09 mV with the increase in sonication power. SEM revealed smaller, disintegrated and irregular shaped RS particles after ultrasonication. FT-IR showed the decreased the band intensity at 995 cm⁻¹ and 1047 cm⁻¹ signifying that US treatment decreased the crystallinity of RS and increased its amorphous character. The bile acid binding, anti-oxidant and pancreatic lipase inhibition activity of samples also increased significantly (p < 0.05) with the increase in sonication power. Increase in US power however increased the values of hydrolysis from 23.11 ± 1.09 to 36.06 ± 0.13% and gylcemic index from 52.39 ± 0.38 to 59.50 ± 0.11. Overall, the non-thermal process of ultrasonic treatment can be used to change the structural, morphological and nutraceutical profile of lotus stem resistant starch which can have great food and pharamaceutical applications.     

Folate-decorated chitosan/doxorubicin poly(butyl)cyanoacrylate nanoparticles for tumor-targeted drug delivery

A novel chitosan coated poly(butyl cyanoacrylate) (PBCA) nanoparticles loaded doxorubicin (DOX) were synthesized and then conjugated with folic acid to produce a folate-targeted drug carrier for tumor-specific drug delivery. Prepared nanoparticles were surface modified by folate for targeting cancer cells, which is confirmed by FTIR spectroscopy and characterized for shape, size, and zeta potential measurements. The size and zeta potential of prepared DOX-PBCA nanoparticles (DOX-PBCA NPs) were almost 174 ± 8.23 nm and +23.14 ± 4.25 mV, respectively with 46.8 ± 3.32% encapsulation capacity. The transmission electron microscopy study revealed that preparation allowed the formation of spherical nanometric and homogeneous. Fluorescent microscopy imaging and flow cytometry analysis revealed that DOX-PBCA NPs were endocytosed into MCF-7 cells through the interaction with overexpressed folate receptors on the surface of the cancer cells. The results demonstrate that folate-conjugated DOX-PBCA NPs drug delivery system could provide increased therapeutic benefit by delivering the encapsulated drug to the folate receptor positive cancer cells.     

Preparation,characterization, and biological activity of Cinnamomum cassia essential oil nano-emulsion

To solve the problems of low bioavailability and unstable properties of Cinnamomum cassia Essential oil (CCEO), encapsulation technology was introduced as an effective means to improve its shortcomings. In this study, Cinnamomum cassia Essential oil nano-emulsion (CCEO-NE) was successfully synthesized by the oil-in-water method and characterized by standard analytical methods, including dynamic light scattering (DLS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The results show that the synthesized CCEO is spherical, smooth in surface, and uniform in shape, with an average particle size of 221.8 ± 1.95 nm, which is amorphous. In this experiment, by simulating the digestion of CCEO-NE in the gastrointestinal tract, it was found that CCEO-NE was undigested in the oral cavity, mainly in the stomach, followed by the small intestine. By understanding the digestion of CCEO-NE, we can improve the potential of CCEO bioavailability in food and drug applications. In addition, through the study of ABTS and DPPH free radicals by CCEO and CCEO-NE, it was found that the antioxidant activity of CCEO-NE was more potent than that of CCEO. When the concentration of CCEO-NE and CCEO is 400 μg/mL, the DPPH free radical scavenging rate is 92.03 ± 0.548% and 80.46 ± 5.811%, respectively. In comparison, ABTS free radical scavenging rate is 90.35 ± 0.480% and 98.44 ± 0.170% when the concentration of CCEO- NE, and CCEO is 75 μg/mL, respectively. The antibacterial test shows that CCEO-NE can inhibit both Gram-positive and Gram-negative bacteria. Among them, CCEO-NE has a stronger antibacterial ability than CCEO, and the maximum inhibition zone diameter of CCEO can reach 15 mm, while that of CCEO-NE can reach 18 mm. Meanwhile, SEM and TEM showed that CCEO-NE treatment destroyed the ultrastructure of bacteria. Generally speaking, we know the situation of CCEO in the gastrointestinal tract. CCEO-NE has more potent antioxidant and antibacterial ability than CCEO. Our research results show that whey protein is an effective packaging strategy that can improve the effectiveness, stability, and even bioavailability of CCEO in various applications, including food and health care industries.     

Interlaboratory comparison for the measurement of particle size and zeta potential of silica nanoparticles in an aqueous suspension

The Institute for Reference Materials and Measurements has organised an interlaboratory comparison (ILC) to allow the participating laboratories to demonstrate their proficiency in particle size and zeta potential measurements on monomodal aqueous suspensions of silica nanoparticles in the 10–100 nm size range. The main goal of this ILC was to identify competent collaborators for the production of certified nanoparticle reference materials. 38 laboratories from four different continents participated in the ILC with different methods for particle sizing and determination of zeta potential. Most of the laboratories submitted particle size results obtained with centrifugal liquid sedimentation (CLS), dynamic light scattering (DLS) or electron microscopy (EM), or zeta potential values obtained via electrophoretic light scattering (ELS). The results of the laboratories were evaluated using method-specific z scores, calculated on the basis of consensus values from the ILC. For CLS (13 results) and EM (13 results), all reported values were within the ±2 |z| interval. For DLS, 25 of the 27 results reported were within the ±2 |z| interval, the two other results were within the ±3 |z| interval. The standard deviations of the corresponding laboratory mean values varied between 3.7 and 6.5%, which demonstrates satisfactory interlaboratory comparability of CLS, DLS and EM particle size values. From the received test reports, a large discrepancy was observed in terms of the laboratory’s quality assurance systems, which are equally important for the selection of collaborators in reference material certification projects. Only a minority of the participating laboratories is aware of all the items that are mandatory in test reports compliant to ISO/IEC 17025 (ISO General requirements for the competence of testing and calibration laboratories. International Organisation for Standardization, Geneva, 2005b). The absence of measurement uncertainty values in the reports, for example, hindered the calculation of zeta scores.     

Highly bacterial resistant silver nanoparticles: synthesis and antibacterial activities

In this article, we describe a simple one-pot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO₃ using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block co-polymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–vis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 ± 1.5 nm (σ = 18.3%) and 31.1 ± 4.5 nm (σ = 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive (Bacillus megaterium and Staphylococcus aureus), and three Gram negative (Escherichia coli, Proteus vulgaris and Shigella sonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.     

Microstructure and morphology of electrodeposited Ni-P alloys treated by high energy surface mechanical attrition

Fully amorphous Ni-P layer electrodeposited onto a Cu plate was subjected to severe plastic deformation using surface mechanical attrition treatment in a high energy SPEX 8000 shaker mill. Two series of experiments using different milling conditions (series I: 20 6.35-mm balls; series II: 100 1.59-mm balls) were carried out to explore the mechanism of the process and to investigate the structure of the developed coatings. The evolution of the microstructure and mechanical properties of the Ni-P layer after the deformation process was studied by x-ray diffraction, scanning electronmicroscopy and hardness measurements. We demonstrate that the different mechanical treatments controllably influence the mechanical behavior of the Ni-P metallic glass coating. When the vial of the mill is loaded with larger balls, deformation-induced Ni₃P compound particles form in the amorphous matrix resulting in a hard (HV = 17 GPa) but non-uniform coating. In the case of milling with many small balls, the increase in the surface hardness is considerably lower (7 GPa) as a consequence of reduced impact energy.     

Dynamic light scattering and <Superscript>31</Superscript>P NMR spectroscopy study of the self-assembly of deoxyguanosine 5'-monophosphate

Self-assembling properties of deoxyguanosine 5'-monophosphate in isotropic solutions of concentrations from 0.5 wt% to 15 wt% were investigated by dynamic light scattering (DLS) and ³¹P NMR spectroscopy. A slow diffusive mode with a diffusion coefficient D _slow∼ 10^-12 m²/s was detected by DLS for the whole concentration range. This mode is assigned to the translational motion of large globular aggregates, similar to those observed in DNA and other polyelectrolyte solutions. The existence of such aggregates was confirmed by freeze fracture electron microscopy. Close to the isotropic-cholesteric phase transition, at 4 wt% c 10 wt%, also a faster diffusive mode is observed in the polarized DLS response and a very fast mode is detected by depolarized DLS. These modes are related to translational and rotational diffusion of the columnar stacks of guanosine molecules, which are favorably formed in the relatively narrow pretransitional region. The stacking was also revealed from the appearance of a secondary resonance line in the ³¹P NMR spectra. Using the hydrodynamic theory of Tirado and Garcia de la Torre, the length of the cylindrical stacks was found to be L = 364±78 ?, which is significantly larger than the values reported for other guanosine derivatives. Received 13 July 2001 and Received in final form 17 October 2001     

The effect of cerium oxide argon-annealed coatings on the high temperature oxidation of a FeCrAl alloy

Ceria coatings were applied in order to improve the adherence of alumina scales developed on a model Fe–20Cr–5Al alloy during oxidation at high temperature. These coatings were performed by argon annealing of a ceria sol–gel coating at temperatures ranging between 600 and 1000 °C. The influence of these coatings on the alloy oxidation behaviour was studied at 1100 °C. In situ X-ray diffraction (XRD) was performed to characterize the coating crystallographic nature after annealing and during the oxidation process. The alumina scale morphologies were studied by means of scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The present work shows that the alumina scale morphology observed on cerium sol–gel coated alloy was very convoluted. On the cerium sol–gel coated alloy, argon annealing results in an increase of the oxidation rate in air, at 1100 °C. The 600 °C argon annealing temperature results in a good alumina scale adherence under thermal cycling conditions at 1100 °C.     

Acrylic coatings exhibiting improved hardness, solvent resistance and glossiness by using silica nano-composites

To prepare nano-composite emulsion acrylic resins with improved surface hardness and solvent resistance, nano-silica particles were treated with surfactants. The monomers of methyl methacrylate/butylacrylate were co-polymerized on the surface of dispersed silica particles. Several emulsions with different silica contents and copolymer mole fractions were prepared. Finally the emulsions were modified to water-based acrylic coatings and improved properties such as surface hardness, solvent resistance and glossiness were determined. The study of coatings was directed to find the improved resin by optimum surface properties. Size distribution and morphology of latexes were characterized by Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy and scanning electron microscopy. The glass transition temperature of nano-composites was measured and discussed its relation with silica contents, monomer mole fractions and improved properties of coatings. The optimum pendulum hardness of coatings was on 0.46 methyl methacrylate mole fraction and 120 g silica content. An increase in pendulum hardness of nano-composites with the addition of modified silica was observed. DLS and TEM studies indicate that silica particles were dispersed homogenously through the polymer matrix.     

Particle agglomeration and properties of nanofluids

The present study demonstrates the importance of actual agglomerated particle size in the nanofluid and its effect on the fluid properties. The current work deals with 5 to 100 nm nanoparticles dispersed in fluids that resulted in 200 to 800 nm agglomerates. Particle size distributions for a range of nanofluids are measured by dynamic light scattering (DLS). Wet scanning electron microscopy method is used to visualize agglomerated particles in the dispersed state and to confirm particle size measurements by DLS. Our results show that a combination of base fluid chemistry and nanoparticle type is very important to create stable nanofluids. Several nanofluids resulted in stable state without any stabilizers, but in the long term had agglomerations of 250 % over a 2 month period. The effects of agglomeration on the thermal and rheological properties are presented for several types of nanoparticle and base fluid chemistries. Despite using nanodiamond particles with high thermal conductivity and a very sensitive laser flash thermal conductivity measurement technique, no anomalous increases of thermal conductivity was measured. The thermal conductivity increases of nanofluid with the particle concentration are as those predicted by Maxwell and Bruggeman models. The level of agglomeration of nanoparticles hardly influenced the thermal conductivity of the nanofluid. The viscosity of nanofluids increased strongly as the concentration of particle is increased; it displays shear thinning and is a strong function of the level of agglomeration. The viscosity increase is significantly above of that predicted by the Einstein model even for very small concentration of nanoparticles.     

Nanocomposite Ni–TiN coatings prepared by ultrasonic electrodeposition

Nanocomposite Ni–TiN coatings were prepared by ultrasonic electrodeposition and the effects of ultrasonication on the coatings were studied. X-ray diffraction analysis was utilized to detect the crystalline and amorphous characteristics of the composite coatings. The surface morphology and metallurgical structure were observed by scanning electron microscopy, high-resolution transmission electron microscopy and scanning probe microscopy. The results showed that ultrasonication had great effects on TiN nanoparticles in composite coatings. The moderate ultrasonication conduced to homogeneous dispersion of TiN particles in the coatings. Moreover, the TiN nanoparticles that entered and homogeneously dispersed in the composite coating led to an increase in the number of nuclei for nucleation of nickel grains and inhibition of grain growth. Therefore, the introduction of ultrasonication and TiN nanoparticles resulted in the formation of smaller nickel grains. The average grain diameter of TiN particles was ∼33 nm, while Ni grains measured approximately 53 nm.     

Composition and structure-property relationships of chromium-diboride/molybdenum-disulphide PVD nanocomposite hard coatings deposited by pulsed magnetron sputtering

The composition and structure-property relationships of physical vapour deposited coatings containing mixtures of CrB₂ and MoS₂ are reported. The coatings were produced by pulsed magnetron sputtering of loosely-packed powder targets formed from a blend of chromium and boron powders, alloyed with 12.8, 18.9 and 24.0 atom percent MoS₂. Results of coating characterisation (by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Auger electron spectroscopy and nanoindentation measurement of hardness and elastic modulus) revealed that increasing amounts of MoS₂ produced the following effects: frustration of crystallisation and phase separation; a decrease in average grain sizes (from ∼5.5 to ∼ 4.3 nm) and a decrease in coating hardness (from ∼15 to ∼ 10 GPa). Scratch testing also showed that the load-bearing capability of coatings was altered; coatings possessing an intermediate concentration of MoS₂ exhibited the best behaviour with no failure observed in mechanical testing, due to an optimal nanocomposite structure. The corrosion resistance (investigated by potentiodynamic polarisation tests) however tended to improve as more MoS₂ was introduced. An investigation of the effects of generating an amorphous structure by adding Ti and C into Cr-B-MoS₂ coatings revealed improved corrosion behaviour, which significantly exceeded that of uncoated stainless steel and CrB₂-coated samples. PACS 68.37.Lp; 68.55.A-; 68.55.Ln; 68.55.Nq; 68.60.Bs     

Fabrication of polymeric nanocapsules from curcumin-loaded nanoemulsion templates by self-assembly

In this study, biodegradable polymeric nanocapsules were prepared by sequential deposition of food-grade polyelectrolytes through the self-assembling process onto the oil (medium chain triglycerides) droplets enriched with curcumin (lipophilic bioactive compound). Optimum conditions were used to prepare ultrasound-assisted nanoemulsions stabilized by octenyl-succinic-anhydride (OSA)-modified starch. Negatively charged droplets (−39.4 ± 1.84 mV) of these nanoemulsions, having a diameter of 142.7 ± 0.85 nm were used as templates for the fabrication of nanocapsules. Concentrations of layer-forming cationic (chitosan) and anionic (carboxymethylcellulose) biopolymers were optimized based on the mean droplet/particle diameter (MDD/MPD), polydispersity index (PDI) and net charge on the droplets/capsules. Prepared core–shell structures or nanocapsules, having MPD of 159.85 ± 0.92 nm, were characterized by laser diffraction (DLS), ζ-potential (ZP), atomic force microscopy (AFM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Furthermore, physical stability of curcumin-loaded nanocapsules in suspension was determined and compared at different storage temperatures. This study may provide information regarding the formation of ultrasound-assisted polymeric nanocapsules from the nanoemulsion templates which could be helpful in the development of delivery systems for lipophilic food bioactives.     

Preparation of PEO ceramic coating on Ti alloy and its high temperature oxidation resistance

Ceramic coatings were prepared in Na₂SiO₃–Na₂CO₃–NaOH system by pulsed bi-polar plasma electrolytic oxidation on Ti–6Al–4V alloy. The phase composition, structure and the elemental distribution of the coatings were studied by XRD, SEM and energy dispersive spectroscopy, respectively. The thermal shock resistance of the coated samples at 850 °C was evaluated by the thermal shock tests. The high temperature oxidation resistance of the coating samples at 500 °C was investigated. The results showed that the coating was mainly composed of rutile- and anatase TiO₂, Increasing the concentration of Na₂SiO₃, TiO₂ content decreased gradually while the thickness of the coating increased. There were a large amount of micro pores and sintered particles on the surface of the coatings. Increasing concentration of Na₂SiO₃, the sintered particles on the surface turned large, and the Si content increased while the Ti content decreased gradually. When the concentration of Na₂SiO₃ was 15 g/L, the thermal shock resistance of the coatings was better than that of the coatings that prepared under other Na₂SiO₃ concentrations. The coating samples prepared under the optimized technique process based on the thermal shock tests improved the high temperature oxidation resistance at 500 °C greatly, whether considering the isothermal oxidation or the cyclic oxidation.     

An optimized MP2RAGE sequence for studying both brain and cervical spinal cord in a single acquisition at 3T

Magnetization Prepared 2 Rapid Acquisition Gradient Echo (MP2RAGE) is a T₁ mapping technique that has been used broadly on brain and recently on cervical spinal cord (cSC).The growing interest for combined investigation of brain and SC in numerous pathologies of the central nervous system such as multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and traumatic injuries, now brings about the need for optimization with regards to this specific investigation. This implies large spatial coverage with high spatial resolution and short acquisition time, high CNR and low B₁⁺ sensitivity, as well as high reproducibility and robust post-processing tools for T₁ quantification in different regions of brain and SC.In this work, a dedicated protocol (referred to as Pr-BSC) has been optimized for simultaneous brain and cSC T₁ MP2RAGE acquisition at 3T. After computer simulation optimization, the protocol was applied for in vivo validation experiments and compared to previously published state of the art protocols focusing on either the brain (Pr-B) or the cSC (Pr-SC). Reproducibility and in-ROI standard deviations were assessed on healthy volunteers in the perspective of future clinical use.The mean T₁ values, obtained by the Pr-BSC, in brain white, gray and deep gray matters were: (mean ± in-ROI SD) 792 ± 27 ms, 1339 ± 139 ms and 1136 ± 88 ms, respectively. In cSC, T₁ values for white matter corticospinal, posterior sensory, lateral sensory and rubro/reticulospinal tracts were 902 ± 41 ms, 920 ± 35 ms, 903 ± 46 ms, 891 ± 41 ms, respectively, and 954 ± 32 ms for anterior and intermediate gray matter. The Pr-BSC protocol showed excellent agreement with previously proposed Pr-B on brain and Pr-SC on cSC, with very high inter-scan reproducibility (coefficients of variation of 0.52 ± 0.36% and 1.12 ± 0.62% on brain and cSC, respectively).This optimized protocol covering both brain and cSC with a sub-millimetric isotropic spatial resolution in one acquisition of less than 8 min, opens up great perspectives for clinical applications focusing on degenerative tissue such as encountered in MS and ALS.     

Formation of titania composite coatings on carbon steel by plasma electrolytic oxidation

Titania composite coatings were prepared on carbon steel by plasma electrolytic oxidation in silicate electrolyte and aluminate electrolyte with titania powers doping in the electrolytes. The microstructure of the coatings was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The properties of the coatings including bond strength, thickness, thermal shock resistance and corrosion resistance varying with the quantities of titania powers in the electrolytes were studied. Investigation results revealed that the coating obtained in silicate electrolyte was composed of anatase-TiO₂, rutile-TiO₂ crystal phases and some Fe, Si, P elements; coating obtained in aluminate electrolyte consisted of anatase-TiO₂, Al₂TiO₅ and some Fe, P elements. Coatings obtained in two types of electrolytes show porous and rough surface. With increasing the concentration of titania powers in the electrolytes, the coating surface first became more compact and less porous and then became more porous and coarse. The bond strength and thickness were not strongly affected by concentration of titania powers in electrolytes. The valves were 23 MPa and for 66 μm for coatings obtained in aluminate electrolyte, and 21 MPa and 35 μm for coatings obtained in silicate electrolyte. Coatings obtained in silicate electrolyte showed a little better thermal shock resistance than those obtained in aluminate electrolyte and the best coatings were obtained with middle concentration of titania powers in the electrolytes. All coated samples showed better corrosion resistance than the substrate in 3.5 wt% NaCl solution. The best coatings were also obtained with middle concentration of titania powers doping in both electrolytes whose corrosion current density was decreased by 2 orders of magnitude compared with the substrate.     

Formation of Al2O3 coatings on NiTi alloy by micro-arc oxidation method

Rough and porous Al₂O₃ coatings containing Ca and P were prepared on Ti–50.8 at.% Ni alloy by micro-arc oxidation (MAO) technique. The microstructure, elemental and phase composition of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS) and thin-film X-ray diffraction (TF-XRD). The thickness of the coatings was measured by eddy current coating thickness gauge. The corrosion resistance and the nickel release of the coated and uncoated samples were examined by potentiodynamic polarization tests and immersion tests in Hank’s solution, respectively. The results show that the coatings are mainly composed of γ-Al₂O₃ crystal phase. The Ni content of the coatings is about 3.5 at.%, which is greatly lower than that of NiTi substrate. With increasing treatment time, both thickness and roughness of the coatings increase. The corrosion resistance of the coated samples is about two orders of magnitude higher than that of the uncoated NiTi alloy. The concentration of Ni released from coated NiTi samples is much lower than that of uncoated NiTi sample. It can be reduced in the factor of one-seventh compared with the uncoated NiTi sample after 3 weeks immersion in Hank’s solution.     

Zn-ZrO2 nanocomposite coatings: Elecrodeposition and evaluation of corrosion resistance

The Zn and Zn-ZrO₂ composite coatings were produced by electrodeposition technique using sulphate bath. ZrO₂ particles were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The ZrO₂ particle size distribution in the plating bath and Zeta potential and the ZrO₂ were measured using dynamic light scattering technique (DLS). The corrosion resistance properties of Zn and Zn-ZrO₂ composite coatings were compared by examining the experimental data acquired through polarization, open circuit potential (OCP) and Tafel measurements. The corrosion environment was 3.5 wt% NaCl solution. The variation of amount of ZrO₂ in the solution on their % wt inclusion in the composite and on composite microhardness was investigated. XRD patterns were recorded for Zn and Zn-ZrO₂ coatings to compare their grain size. The SEM images of coatings before and after corrosion under chemical and electrochemical conditions were presented. The results were analyzed to establish the superiority of Zn-ZrO₂ composite over Zn coating.     

Nanocomposite and nanostructured superhard Ti-Si-B-N coatings

Electron microscopy, x-ray diffraction analysis, and micro-and nanohardness measurements were used to investigate the interrelations between the fine structure and the variations in strength properties of nanostructured and nanocomposite Ti-Si-B-N coatings with high oxygen and carbon contents. It has been shown that under the conditions of low-temperature (T = 200°C) coating deposition, a two-level grain structure forms with {200} texture and grains 0.1–0.3 μm in size fragmented into subgrains 15–20 nm in size. As the silicon content is increased, textureless coatings with the crystal phase grain size less than 15 nm and high amorphous component or coatings of amorphous-crystalline structure are produced. At coating deposition temperatures of 400–450°C, a nanocomposite structure with a grain size d = 10–15 nm and no texture is observed. For all test compositions and conditions of coating production, a Ti _1−x Si _x N crystal phase with the lattice parameter a = (0.416–0.420) ± 0.001 nm has been detected. For optimum coating compositions and synthesis conditions, the hardness is over 40–50 GPa. It has been supposed that superhardness can be attained with multiphase grain-boundary interlayers of thickness more than 1 nm. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 13–23, October, 2007.     

Formulation and characterisation of drug-loaded antibubbles for image-guided and ultrasound-triggered drug delivery

The aim of this study was to develop high load-capacity antibubbles that can be visualized using diagnostic ultrasound and the encapsulated drug can be released and delivered using clinically translatable ultrasound.The antibubbles were developed by optimising a silica nanoparticle stabilised double emulsion template.We produced an emulsion with a mean size diameter of 4.23 ± 1.63 µm where 38.9 ± 3.1% of the droplets contained a one or more cores. Following conversion to antibubbles, the mean size decreased to 2.96 ± 1.94 µm where 99% of antibubbles were <10 µm. The antibubbles had a peak attenuation of 4.8 dB/cm at 3.0 MHz at a concentration of 200 × 10³ particles/mL and showed distinct attenuation spikes at frequencies between 5.5 and 13.5 MHz. No increase in subharmonic response was observed for the antibubbles in contrast to SonoVue®. High-speed imaging revealed that antibubbles can release their cores at MIs of 0.6. In vivo imaging indicated that the antibubbles have a long half-life of 68.49 s vs. 40.02 s for SonoVue®. The antibubbles could be visualised using diagnostic ultrasound and could be disrupted at MIs of ≥0.6. The in vitro drug delivery results showed that antibubbles can significantly improve drug delivery (p < 0.0001) and deliver the drug within the antibubbles. In conclusion antibubbles are a viable concept for ultrasound guided drug delivery.