Nanoscale organization of mitochondrial microcompartments revealed by combining tracking and localization microscopy

While detailed information on the nanoscale-organization of proteins within intracellular membranes has emerged from electron microcopy, information on their spatiotemporal dynamics is scarce. By use of a photostable rhodamine attached specifically to Halo-tagged proteins in mitochondrial membranes, we were able to track and localize single protein complexes such as Tom20 and ATP synthase in suborganellar structures in live cells. Individual membrane proteins in the inner and outer membrane of mitochondria were imaged over long time periods with localization precisions below 15 nm. Projection of single molecule trajectories revealed diffusion-restricting microcompartments such as individual cristae in mitochondria. At the same time, protein-specific diffusion characteristics within different mitochondrial membranes could be extracted.     

Fabrication,chemical composition change and phase evolution of biomorphic hydroxyapatite

Biomorphous, highly porous hydroxyapatite (HA) ceramics have been prepared by a combination of a novel biotemplating process and a sol-gel method, using natural plants like cane and pine as biotemplates. A HA sol was first synthesized from triethylphosphate and calcium nitrate used as the phosphorus and calcium precursors, respectively, and infiltrated into the biotemplates, and subsequently they were sintered at elevated temperatures to obtain porous HA ceramics. The microstructural changes, phase and chemical composition evolutions during the biotemplate-to-HA conversion were investigated by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy. The XRD and FT-IR analysis revealed that the dominant phase of the product was HA, which contained a small amount of mixed A/B-type carbonated HA, closely resembling that of human bone apatite. Moreover, the appearance of a small amount of secondary phase CaCO(3) seemed unavoidable. The HA was not transformed to the other calcium phosphate phases up to 1400 degrees C, but it contained a trace amount of CaO when sintered at above 1100 degrees C. The possible transformation mechanism was proposed. The SEM observation and mechanical property test showed that as-produced HA ceramics retained the macro-/micro-porous structures of the biotemplates with high precision, and possessed acceptable mechanical strength, which is suggested to be potential scaffolds for bone tissue engineering.     

Straight and kinked InAs nanowire growth observed in situ by transmission electron microscopy

Live observations of growing nanowires using in situ transmission electron microscopy （TEM） is becoming an increasingly important tool for understanding the dynamic processes occurring during nanowire growth. Here we present observations of growing InAs nanowires, which constitute the first reported in situ growth of a In-V compound in a transmission electron microscope. Real time observations of events taking place over longer growth lengths were possible due to the high growth rates of up to I nm/s that were achieved. Straight growth （mainly in 〈111〉B directions） was observed at uniform temperature and partial pressure while intentional fluctuations in these conditions caused the nanowires to form kinks and change growth direction. The mechanisms behind the kinking are discussed in detail. In situ observations of nanowire kinking has previously only been reported for nonpolar diamond structure type materials （such as Si）, but here we present results for a polar zinc blende structure （InAs）. In this study a closed cell with electron and X-ray transparent a-SiN windows was used in a conventional high resolution transmission electron microscope, enabling high resolution imaging and compositional analysis in between the growth periods.     

Synthesis of single crystal metal sulfide nanowires and nanowire arrays by chemical precipitation in templates

Single crystal metal sulfide nanowires and nanowire arrays were synthesized by chemical precipitation reaction in the channels of anodic aluminum oxide templates under ambient conditions with simple inorganic salts as precursors. Aligned metal sulfide arrays were achieved by dissolving the template. This template-directed synthesis yielded well-defined nanowires of varied lengths and diameters for almost all precursors. The crystal quality of metal sulfide nanowires was concentration-dependent, high single crystal nanowires were achieved at low concentrations.     

Homogenous indium distribution in InGaN/GaN laser active structure grown by LP-MOCVD on bulk GaN crystal revealed by transmission electron microscopy and x-ray diffraction

We present transmission electron microscopy (TEM) and x-ray quantitative studies of the indium distribution in In(x)Ga(1-x)N/GaN multiple quantum wells (MQWs) with x = 0.1 and 0.18. The quantum wells were grown by low-pressure metalorganic chemical vapour deposition (LP-MOCVD) on a bulk, dislocation-free, mono-crystalline GaN substrate. By using the quantitative TEM methodology the absolute indium concentration was determined from the 0002 lattice fringe images by the strain measurement coupled with finite element (FE) simulations of surface relaxation of the TEM sample. In the x-ray diffraction (XRD) investigation, a new simulation program was applied to monitor the indium content and lateral composition gradients. We found a very high quality of the multiple quantum wells with lateral indium fluctuations no higher than Δx(L) = 0.025. The individual wells have very similar indium concentration and widths over the whole multiple quantum well (MQW) stack. We also show that the formation of 'false clusters' is not a limiting factor in indium distribution measurements. We interpreted the 'false clusters' as small In-rich islands formed on a sample surface during electron-beam exposure.     

Elastic deformation behavior and microstructure evolution of single crystal nickel nanowire in tensile test along [0 0 1] orientation

Elastic deformation behavior and microstructure evolution of single crystal nickel nanowire in tensile test have been investigated using molecular dynamics simulations. When the temperature is above 300 K, the deformation of nanowire is inhomogeneous in the elastic stage. It can generate a kind of (body‐centered cubic)‐like structure within the material to guide the elastic deformation, rather than the uniform deformation of all the atoms. The (body‐centered cubic)‐like structure will transform to be a body‐centered cubic structure gradually with the increasing of strain and will revert to be a face‐centered cubic structure when the twin crystal appears. The formation of (body‐centered cubic)‐like structure could reduce the density of the material to resist deformation. Besides, the (body‐centered cubic)‐like structure increase with increasing of strain or temperature, and they will gather together to reduce the interface energy. Our conclusion also can be proved by the radial distribution functions g(r).     

Simultaneous interface and interband lasing in InAs/InAsSbP heterostructures grown by metalorganic vapor phase epitaxy

Coherent radiation sources have been manufactured based on double heterostructures of the InAs/InAsSbP type grown by metalorganic vapor-phase epitaxy. The mode composition of the lasing spectrum is determined by simultaneous induced recombination at the heteroboundary and in the bulk of the active region, as well as nongenerated modes with intermediate frequencies. Additional optical losses at the intermediate modes decrease the slope of the laser intensity dependence on the current.     

Ferroelectric domain in PMN-xPT single crystal studied by piezoresponse force microscopy and finite-element analysis

Ferroelectric domain structures in (001)-cut Pb(Mg(1/3)Nb(2/3))O(3)-38%PbTiO(3) and (011)-cut Pb(Mg(1/3) Nb(2/3))O(3)-60%PbTiO(3) single crystals are studied by means of piezoresponse force microscopy (PFM). The out-of-plane- polarization (OPP) and in-plane-polarization (IPP) domain piezoresponse imaging reveals the domain and domain boundary configurations in these two different PbTiO(3)-content crystals. Finite-element analysis is carried out to illustrate the OPP and IPP-PFM imagings mechanism and interpret the domains superposition phenomenon during PFM imaging.     

Structure, spectra and phase transition in p-nitroanilinium perchlorate crystal

The first X-ray diffraction and vibrational spectroscopic analysis of a novel complex between p-nitroaniline and perchloric acid is reported. The structure was solved in 295 K. Room temperature powder infrared and Raman measurements for the p-nitroanilinium perchlorate (1:1) crystals were carried out. The vibrational spectra in the region of internal vibrations of ions corroborates the X-ray data which show that p-nitroaniline molecule is monoprotonated. DSC measurements on powder sample indicate the phase transition point at about 213 and 208 K for heating and cooling, respectively. No detectable signal was observed during powder test for second harmonic generation.     

Mechanical properties of Si nanowires as revealed by in situ transmission electron microscopy and molecular dynamics simulations

Deformation and fracture mechanisms of ultrathin Si nanowires (NWs), with diameters of down to ~9 nm, under uniaxial tension and bending were investigated by using in situ transmission electron microscopy and molecular dynamics simulations. It was revealed that the mechanical behavior of Si NWs had been closely related to the wire diameter, loading conditions, and stress states. Under tension, Si NWs deformed elastically until abrupt brittle fracture. The tensile strength showed a clear size dependence, and the greatest strength was up to 11.3 GPa. In contrast, under bending, the Si NWs demonstrated considerable plasticity. Under a bending strain of <14%, they could repeatedly be bent without cracking along with a crystalline-to-amorphous phase transition. Under a larger strain of >20%, the cracks nucleated on the tensed side and propagated from the wire surface, whereas on the compressed side a plastic deformation took place because of dislocation activities and an amorphous transition.     

Effect of domains configuration on crystal structure in ferroelectric ceramics as revealed by XRD and dielectric spectrum

It is well known that domains and crystal structure control the physical properties of ferroelectrics. The ex-situ electric field-dependent structural study, carried out in unpoled/poled crushed powder and bulk samples for \((\hbox {Li}_{0.5} \hbox {Nd}_{0.5})^{2+}\) modified 0.95\(\hbox {Bi}_{0.5} \hbox {Na}_{0.5} \hbox {TiO}_{3}{-}\mathrm{0.05} \hbox {BaTiO}_{3}\) solid solution, established a correlation between domain configuration and crystal structure variation. Under applying electric field, the smeared ferroelectric phase structure due to coherence diffraction effect of nanodomains reappeared due to obsolescent coherence effect associated with the field-induced ordered nanodomains. The macroscopic characterizing techniques of domain configuration such as dielectric constant spectroscopy and X-ray diffraction measurement can provide a basis for understanding the correlation between domains configuration and crystal structure in ferroelectric ceramics.     

Characteristics of receptor- and transducer-coupled activation of the intracellular signalling in sensory neuron revealed by atomic force microscopy

Technical Physics Letters - The mechanical properties of sensory neurons upon activation of intracellular cascade processes by comenic acid binding to a membrane opioid-like receptor...     

Complex use of the diffraction techniques in depth profiling of the crystal lattice parameter and composition of InGaAs/GaAs gradient layers

A technique is proposed for testing thick (1 μm and larger) gradient layers with the composition and relaxation degree alternating over the layer depth on the basis of comparative analysis of X-ray scattered intensity maps in the reciprocal space and depth profiles of the crystal lattice parameters obtained by electron microdiffraction. The informativity of the proposed technique is demonstrated using the example of an In _x Ga_1–x As/GaAs layer with linear depth variation in x. Complex representation of the diffraction data in the form of the depth-profiled reciprocal space map allows taking into account the additional relaxation caused by thinning electron microscopy specimens.     

Effect of vacuum annealing on the phase composition of In/SnO/Si, In/SnO2/Si, and Sn/In2O3/Si heterostructures

The chemical interaction between indium and thin SnO and SnO₂ films and between tin and thin In₂O₃ films during vacuum annealing was studied. The metallic films were deposited onto single-crystal silicon substrates by magnetron sputtering, the SnO and SnO₂ films were produced by heat-treating the Sn film in flowing oxygen at 673 and 873 K, respectively, and the In₂O₃ film was produced by heat-treating the In film at 573 K. The results indicate that annealing of the In/SnO/Si and In/SnO₂/Si heterostructures in vacuum (residual pressure of 0.33 × 10^?2 Pa) at 773 K gives rise to the reduction of Sn and oxidation of In, whereas annealing of Sn/In₂O₃/Si causes partial tin substitution for indium in the cubic indium oxide lattice.     

Stoichiometry, phase composition, and properties of superhard nanostructured Ti-Hf-Si-N coatings obtained by deposition from high-frequency vacuum-arc discharge

Superhard nanostructured Ti-Hf-Si-N coatings (films) possessing high mechanical properties were obtained by deposition from high-frequency vacuum-arc discharge. The elemental and phase composition and morphology of the films were studied by a combination of methods including RBS, SIMS, GDMS, SEM-EDXS, XRD and nanoindentation techniques at various pressures and bias voltages applied to the coated samples. It is established that, as the average grain size in nc-(Ti,Hf)N (nanocrystalline) coatings decreases from 6.7 to 5 nm and a-Si₃N₄ (amophous or quasi-amorphous phase) interlayers are formed between the nanograins, the nanohardness of coatings increases from 42.7 to 48.4–1.6 GPa. However, the further grain refinement of nc-(Ti,Hf)N to 4.0 nm leads to a slight decrease in the nanohardness. The stoichiometry of the coatings changes from (Ti₂₅-Hf_12.5-Si_12.5)N₅₀ to (Ti₂₈-Hf₁₈-Si₉)N₄₅, which is accompanied by variation of the lattice parameter of (Ti,Hf)N solid solution grains.     

The nature of the lamellar overgrowth in polyethylene shish-kebab fibres as revealed by small-angle X-ray scattering and electron microscopy

The melting, dissolution and crystallization behaviour of the lamellar overgrowth in polyethylene shish-kebab fibres have been studied by small-angle X-ray scattering and electron microscopy. SAXS experiments in which fibres were heatedin situ demonstrated the irreversible reorganization of the lamellar overgrowth already at 60° C. Reorganization continued in an inhomogeneous manner until the fibre lost its porosity around 140° C. The morphology that developed upon cooling depended on the crystallization temperature as well as on the maximum temperature attained before crystallization. Transmission electron microscopy observations showed the influence of molecular weight on aggregation. The SAXS patterns obtained duringin situ dissolution experiments disclosed that the lamellae dissolved in dodecane above 115° C. Recrystallization of the lamellae on to the backbones was almost complete within 10 min at 110° C. These high temperatures, as compared with single-crystal behaviour, indicate that the cilia nucleated with exceptionally high stem lengths on to the backbones. SAXS of fibres elongated to a maximum ratio of 1.5 at 90° C demonstrated the role of the lamellar overgrowth as a matrix between the elementary fibrils. The shish-kebab morphology could be restored after elongation by selective dissolution of the lamellae and recrystallization.     

电子束蒸镀纳米TiO_2薄膜结构、相组成及亲水性研究

利用电子束蒸镀技术在石英玻璃和单晶Si〈100〉上制备了纳米TiO2薄膜,研究了衬底温度和退火温度对其结构、相组成和亲水性能的影响。结果表明,衬底温度为40~240℃时,石英玻璃上制备的薄膜为无定型TiO2,单晶Si〈100〉上制备的薄膜为弱结晶性的金红石TiO2,两类薄膜的亲水性均很差。退火温度显著影响薄膜的相组成及亲水性能。石英玻璃上不同衬底温度制备的TiO2薄膜经550,650℃退火后均转变为锐钛矿TiO2,具有很好的亲水性能。单晶Si〈100〉上不同衬底温度制备的TiO2薄膜经550~950℃退火后,均由金红石和锐钛矿TiO2混晶组成,且随退火温度升高,薄膜中锐钛矿TiO2含量逐渐增加;随退火温度升高,衬底温度为40℃时制备的TiO2薄膜的亲水性能逐渐降低,而衬底温度为240℃时制备的TiO2薄膜的亲水性能逐渐增强。