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Specimens for transmission electron microscopic (TEM) investigations were prepared from γ titanium aluminide alloys with Gallium and Argon ions using a focused ion beam (FIB) and a precision ion polishing system (PIPS). Preparation to electron transparency by Gallium ions alone leads to the formation of crystalline platelets of the α titanium phase at the specimen surfaces, revealed through conventional and high resolution (HR) TEM analysis. The platelets are assumed to precipitate from priorly formed amorphous layers. The required crystallisation temperature of about 480°C is generated through the ion bombardment implying that the γ titanium aluminides can be heated substantively during sputtering. The primary reason for this is the restricted transfer of heat away from the beam impact point when the specimen thickness comes close to the beam diameter. The formation of the platelets can be avoided by terminating the Gallium ion treatment prior to that, while providing for a sufficient thermal bonding of the specimen to the grid as well and polishing off the remaining material by Argon ions, which are much less focused and less energetic, so that the local heat peaks are reduced. [ABSTRACT FROM AUTHOR]

Photonic glass is a material class that can be used as photonic broadband reflectors, for example in the infrared regime as thermal barrier coating films. Photonic properties such as the reflectivity depend on the ordering and material packing fraction over the complete film thickness of up to 100 µm. Nanotomography allows acquiring these key parameters throughout the sample volume at the required resolution in a non-destructive way. By performing a nanotomography measurement at the PETRA III beamline P05 on a photonic glass film, the packing fraction throughout the complete sample thickness was analyzed. The results showed a packing fraction significantly smaller than the expected random close packing giving important information for improving the fabrication and processing methods of photonic glass material in the future. [ABSTRACT FROM AUTHOR]

Magnesium alloys have been identified as a new generation material of orthopaedic implants. In vitro setups mimicking physiological conditions are promising for material / degradation analysis prior to in vivo studies however the direct influence of cell on the degradation mechanism has never been investigated. For the first time, the direct, active, influence of human primary osteoblasts on magnesium-based materials (pure magnesium, Mg-2Ag and Mg-10Gd alloys) is studied for up to 14 days. Several parameters such as composition of the degradation interface (directly beneath the cells) are analysed with a scanning electron microscope equipped with energy dispersive X-ray and focused ion beam. Furthermore, influence of the materials on cell metabolism is examined via different parameters like active mineralisation process. The results are highlighting the influences of the selected alloying element on the initial cells metabolic activity. [ABSTRACT FROM AUTHOR]

Permanent implants made from titanium are widely used and successfully implemented in medicine to address problems related to orthopedic and oral disorders. However, implants that interact in all cases optimally and durably with bone tissue have yet to be developed. Here, the authors suggest a phospholipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-ethanolamine (POPE) lipid coating to partially mimic the biological cell membrane. To improve the homogeneity of the POPE distribution on the metal surface, the lipids are applied by spray coating. It is shown that the spray coating leads to two types of multilamellar POPE structures. Our experimental results demonstrate that these coatings are stable in a liquid environment in the range of physiological temperatures due to the unique interbilayer interaction of POPE lipids. Additionally, the interaction of the POPE multilayer structure with human serum albumin is considered. A simultaneous analysis of the specular and off-specular data provides structural information necessary to assess the quality of the coating for future applications. [ABSTRACT FROM AUTHOR]

The high flux density encountered in scanning X-ray nanodiffraction experiments can lead to severe radiation damage to biological samples. However, this technique is a suitable tool for investigating samples to high spatial resolution. The layered cell wall structure of softwood tracheids is an interesting system which has been extensively studied using this method. The tracheid cell has a complex geometry, which requires the sample to be prepared by cutting it perpendicularly to the cell wall axis. Focused ion beam (FIB) milling in combination with scanning electron microscopy allows precise alignment and cutting without splintering. Here, results of a scanning X-ray diffraction experiment performed on a biological sample prepared with a focused ion beam of gallium atoms are reported for the first time. It is shown that samples prepared and measured in this way suffer from the incorporation of gallium atoms up to a surprisingly large depth of 1 µm. [ABSTRACT FROM AUTHOR]

Increased durability of permanent TiAl6V4 implants still remains a requirement for the patient's well-being. One way to achieve a better bone-material connection is to enable bone "ingrowth" into the implant. Therefore, a new porous TiAl6V4 material was produced via metal injection moulding (MIM). Specimens with four different porosities were produced using gas-atomised spherical TiAl6V4 with different powder particle diameters, namely, "Small" (<45 μm), "Medium" (45-63 μm), "Mix" (90% 125-180 μm + 10% <45 μm), and "Large" (125-180 μm). Tensile tests, compression tests, and resonant ultrasound spectroscopy (RUS) were used to analyse mechanical properties. These tests revealed an increasing Young's modulus with decreasing porosity; that is, "Large" and "Mix" exhibit mechanical properties closer to bone than to bulk material. By applying X-ray tomography (3D volume) and optical metallographic methods (2D volume and dimensions) the pores were dissected. The pore analysis of the "Mix" and "Large" samples showed pore volumes between 29% and 34%, respectively, with pore diameters ranging up to 175 μm and even above 200 μm for "Large." Material cytotoxicity on bone cell lines (SaOs-2 and MG-63) and primary cells (human bone-derived cells, HBDC) was studied by MTT assays and highlighted an increasing viability with higher porosity. [ABSTRACT FROM AUTHOR]

To improve nanoconfinement of LiBH 4 and MgH 2 in carbon aerogel scaffold (CAS), particle size reduction of MgH 2 by premilling technique before melt infiltration is proposed. MgH 2 is premilled for 5 h prior to milling with LiBH 4 and nanoconfinement in CAS to obtained nanoconfined 2LiBH 4 –premilled MgH 2 . Significant confinement of both LiBH 4 and MgH 2 in CAS, confirmed by SEM–EDS–mapping results, is achieved due to MgH 2 premilling. Due to effective nanoconfinement, enhancement of CAS:hydride composite weight ratio to 1:1, resulting in increase of hydrogen storage capacity, is possible. Nanoconfined 2LiBH 4 –premilled MgH 2 reveals a single–step dehydrogenation at 345 °C with no B 2 H 6 release, while dehydrogenation of nanoconfined sample without MgH 2 premilling performs in multiple steps at elevated temperatures (up to 430 °C) together with considerable amount of B 2 H 6 release. Activation energy ( E A ) for the main dehydrogenation of nanoconfined 2LiBH 4 –premilled MgH 2 is considerably lower than those of LiBH 4 and MgH 2 of bulk 2LiBH 4 –MgH 2 (Δ E A = 31.9 and 55.8 kJ/mol with respect to LiBH 4 and MgH 2 , respectively). Approximately twice faster dehydrogenation rate are accomplished after MgH 2 premilling. Three hydrogen release ( T = 320 °C, P (H 2 ) = 3–4 bar) and uptake ( T = 320–325 °C, P (H 2 ) = 84 bar) cycles of nanoconfined 2LiBH 4 –premilled MgH 2 reveal up to 4.96 wt. % H 2 (10 wt. % H 2 with respect to hydride composite content), while the 1st desorption of nanoconfined sample without MgH 2 premilling gives 4.30 wt. % of combined B 2 H 6 and H 2 gases. It should be remarked that not only kinetic improvement and B 2 H 6 suppression are obtained by MgH 2 premilling, but also the lowest dehydrogenation temperature ( T = 320 °C) among other modified 2LiBH 4 –MgH 2 systems is acquired. [ABSTRACT FROM AUTHOR]

Destabilization of LiBH4 by nanoconfinement in poly (methyl methacrylate)–co–butyl methacrylate (PMMA–co–BM), denoted as nano LiBH4–PMMA–co–BM, is proposed for reversible hydrogen storage. The onset dehydrogenation temperature of nano LiBH4–PMMA–co–BM is reduced to ∼80 °C (ΔT = 340 and 170 °C as compared with milled LiBH4 and nanoconfined LiBH4 in carbon aerogel, respectively). At 120 °C under vacuum, nano LiBH4–PMMA–co–BM releases 8.8 wt.% H2 with respect to LiBH4 content within 4 h during the 1st dehydrogenation, while milled LiBH4 performs no dehydrogenation at the same temperature and pressure condition. Moreover, nano LiBH4–PMMA–co–BM can be rehydrogenated at the mildest condition (140 °C under 50 bar H2 for 12 h) among other modified LiBH4 reported in the previous literature. Due to the hydrophobicity of PMMA–co–BM host, deterioration of LiBH4 by oxygen and humidity in ambient condition is avoided after nanoconfinement. Although the interaction between LiBH4 and the pendant group of PMMA–co–BM leads to a reduced hydrogen storage capacity, significant destabilization of LiBH4 is accomplished. [ABSTRACT FROM AUTHOR]

Abstract: Nanoconfinement of 2LiBH4–MgH2–TiCl3 in resorcinol–formaldehyde carbon aerogel scaffold (RF–CAS) for reversible hydrogen storage applications is proposed. RF–CAS is encapsulated with approximately 1.6 wt. % TiCl3 by solution impregnation technique, and it is further nanoconfined with bulk 2LiBH4–MgH2 via melt infiltration. Faster dehydrogenation kinetics is obtained after TiCl3 impregnation, for example, nanoconfined 2LiBH4–MgH2–TiCl3 requires ∼1 and 4.5 h, respectively, to release 95% of the total hydrogen content during the 1st and 2nd cycles, while nanoconfined 2LiBH4–MgH2 (∼2.5 and 7 h, respectively) and bulk material (∼23 and 22 h, respectively) take considerably longer. Moreover, 95–98.6% of the theoretical H2 storage capacity (3.6–3.75 wt. % H2) is reproduced after four hydrogen release and uptake cycles of the nanoconfined 2LiBH4–MgH2–TiCl3. The reversibility of this hydrogen storage material is confirmed by the formation of LiBH4 and MgH2 after rehydrogenation using FTIR and SR-PXD techniques, respectively. [Copyright &y& Elsevier]

Nanostructures have been widely employed in surface-enhanced Raman scattering (SERS) substrates. Recently, in order to obtain a higher enhancement factor at a lower detection limit, hierarchical structures, including nanostructures and nanoparticles, appear to be viable SERS substrate candidates. Here we describe a novel method integrating the nanoindentation process and chemical redox reaction to machine a hierarchical SERS substrate. The micro/nanostructures are first formed on a Cu(110) plane and then Ag nanoparticles are generated on the structured copper surface. The effect of the indentation process parameters and the corrosion time in the AgNO 3 solution on the Raman intensities of the SERS substrate with hierarchical structures are experimentally studied. The intensity and distribution of the electric field of single and multiple Ag nanoparticles on the surface of a plane and with multiple micro/nanostructures are studied with COMSOL software. The feasibility of the hierarchical SERS substrate is verified using R6G molecules. Finally, the enhancement factor using malachite green molecules was found to reach 5.089 × 10 9 , which demonstrates that the production method is a simple, reproducible and low-cost method for machining a highly sensitive, hierarchical SERS substrate., (Copyright © 2019, Zhang et al.; licensee Beilstein-Institut.)

Permanent implants made from titanium are widely used and successfully implemented in medicine to address problems related to orthopedic and oral disorders. However, implants that interact in all cases optimally and durably with bone tissue have yet to be developed. Here, the authors suggest a phospholipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-ethanolamine (POPE) lipid coating to partially mimic the biological cell membrane. To improve the homogeneity of the POPE distribution on the metal surface, the lipids are applied by spray coating. It is shown that the spray coating leads to two types of multilamellar POPE structures. Our experimental results demonstrate that these coatings are stable in a liquid environment in the range of physiological temperatures due to the unique interbilayer interaction of POPE lipids. Additionally, the interaction of the POPE multilayer structure with human serum albumin is considered. A simultaneous analysis of the specular and off-specular data provides structural information necessary to assess the quality of the coating for future applications.