Nm In Height Research Articles

Isolation and Characterization of Shewanella Phage Thanatos Infecting and Lysing Shewanella oneidensis and Promoting Nascent Biofilm Formation.

Species of the genus Shewanella are widespread in nature in various habitats, however, little is known about phages affecting Shewanella sp. Here, we report the isolation of phages from diverse freshwater environments that infect and lyse strains of Shewanella oneidensis and other Shewanella sp. Sequence analysis and microscopic imaging strongly indicate that these phages form a so far unclassified genus, now named Shewanella phage Thanatos, which can be positioned within the subfamily of Tevenvirinae (Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes; Caudovirales; Myoviridae; Tevenvirinae). We characterized one member of this group in more detail using S. oneidensis MR-1 as a host. Shewanella phage Thanatos-1 possesses a prolate icosahedral capsule of about 110 nm in height and 70 nm in width and a tail of about 95 nm in length. The dsDNA genome exhibits a GC content of about 34.5%, has a size of 160.6 kbp and encodes about 206 proteins (92 with an annotated putative function) and two tRNAs. Out of those 206, MS analyses identified about 155 phage proteins in PEG-precipitated samples of infected cells. Phage attachment likely requires the outer lipopolysaccharide of S. oneidensis, narrowing the phage’s host range. Under the applied conditions, about 20 novel phage particles per cell were produced after a latent period of approximately 40 min, which are stable at a pH range from 4 to 12 and resist temperatures up to 55°C for at least 24 h. Addition of Thanatos to S. oneidensis results in partial dissolution of established biofilms, however, early exposure of planktonic cells to Thanatos significantly enhances biofilm formation. Taken together, we identified a novel genus of Myophages affecting S. oneidensis communities in different ways.

Relationship between the Surface Morphology of Thin YBa2Cu3O7 – x Films Obtained by Pulsed Laser Deposition and the Endset Temperature of Superconducting Transition

A correlation was found between the endset temperature of the superconducting transition T(R = 0) of YBa2Cu3O7 – x films 100–200 nm thick, obtained by pulsed laser deposition on SrTiO3(100) substrates with a temperature of ~740°C, and the regimes of high-speed filtering of the erosion plume formed upon ablation of the material the target. Under deposition conditions, we changed the width of the filtering window, the repetition rate of the atomized material passing through the filter onto the substrate, and the radiation energy density of the KrF excimer laser on the target surface. At deposition rates of less than 0.1 nm s–1, the values of T(R = 0) did not exceed 77 K, and pyramids were formed on the surface of the films up to 80 nm in height along the c axis in the form of spirals with rectangular bases and steps of 1–2 nm along the lateral faces. With an increase in the deposition rate from 0.1 to 0.6 nm s–1, T(R = 0) increased to 86 K. These regimes corresponded to a wavy pyramid surface up to 40 nm in height with rounded bases up to 1500 nm in diameter and irregular steps 1–4 nm on the side slopes. Faceted crystals with a width from 20–30 to 500 nm in the base grew along the boundaries between the pyramids during the deposition. This morphology of the growth surface was explained by the high flow rate of the sputtered material, which is determined by the frequency filtering of the erosion plume and the energy density in the pulse upon predominantly surface diffusion.

Towards the integration of nanoemitters by direct laser writing on optical glass waveguides

A major challenge towards nanophotonics is the integration of nanoemitters on optical chips. Combining the optical properties of nanoemitters with the benefits of integration and scalability of integrated optics is still a major issue to overcome. In this work, we demonstrate the integration of nanoemitters positioned in a controlled manner onto a substrate and onto an optical ion-exchanged glass waveguide via direct laser writing based on two-photon polymerization. Our nanoemitters are colloidal CdSe/ZnS quantum dots (QDs) embedded in polymeric nanostructures. By varying the laser parameters during the patterning process, we make size-controlled QD-polymer nanostructures that were systematically characterized using optical and structural methods. Structures as small as 17 nm in height were fabricated. The well-controlled QD-polymer nanostructure systems were then successfully integrated onto a new photonic platform for nanophotonics made of an ion-exchanged waveguide. We show that our QDs maintain their light emitting quality after integration as verified by photoluminescence (PL) measurements. Ultimately, QD emission coupled to our waveguides is detected through a home-built fiber-edge coupling PL measurement setup. Our results show the potential for future integration of nanoemitters onto complex photonic chips.

Surface Microstructure of Nanocomposite from Chitosan Loaded with ZnO Nanoparticle by Atomic Force Microscopy

In this study, atomic force microscopy (AFM) was employed to characterize the microstructure of chitosan-zinc oxide (ZnO) nanocomposite. Three dimensional image of AFM indicated that ZnO nanoparticles were in the ranging of 0.25-33.33 nm in height, 13-177 nm in diameter (confirmed by particle size analyzer), irregular and triangular cluster in morphologies. Furthermore, ZnO nanoparticles were well incorporated into chitosan solution indicated by UV-vis absorption peak of 359 and 341 nm for ZnO alone and nanocomposite respectively. AFM revealed the relatively continuous matrix without pores, smooth and contoured film were formed from chitosan alone as well as chitosan-ZnO composites. There were no remarkable different for surface roughness of both films indicating ZnO in nano-scale were blended well with chitosan matrix.

Dissolvable Template Nanoimprint Lithography: A Facile and Versatile Nanoscale Replication Technique.

Nanoimprinting lithography (NIL) is a next-generation nanofabrication method, capable of replicating nanostructures from original master surfaces. Here, we develop highly scalable, simple, and nondestructive NIL using a dissolvable template. Termed dissolvable template nanoimprinting lithography (DT-NIL), our method utilizes an economic thermoplastic resin to fabricate nanoimprinting templates, which can be easily dissolved in simple organic solvents. We used the DT-NIL method to replicate cicada wings which have surface nanofeatures of ∼100 nm in height. The master, template, and replica surfaces showed a >∼94% similarity based on the measured diameter and height of the nanofeatures. The versatility of DT-NIL was also demonstrated with the replication of re-entrant, multiscale, and hierarchical features on fly wings, as well as hard silicon wafer-based artificial nanostructures. The DT-NIL method can be performed under ambient conditions with inexpensive materials and equipment. Our work opens the door to opportunities for economical and high-throughput nanofabrication processes.

Solvo-Driven Dimeric Nanoplasmon Coupling Under DNA Direction

Strong coupling is a prerequisite for nanoassemblies to deliver functions and applications unrealizable by noninteracting building units. DNA-Directed metamaterials, albeit highly programmable, oft...

Development of sodium lauryl sulphate stabilized nanosuspension of Coriandrum sativum to enhance its oral bioavailability

The objective of this research work was to increase the dissolution and bioavailability of C. sativum extract in order to increase its therapeutic applications. To achieve this goal, nanosuspensions of ethanolic extract of C. sativum were prepared with six different stabilizers afterwards other formulation conditions were optimized with response surface methodology (RSM). Dimensions and morphology of optimized nanosuspension was determined by employing atomic force microscopy (AFM) and scanning electron microcopy. Based on the initial stabilizer screening study, sodium lauryl sulphate was selected as stabilizer for the development of nanosuspension of C. sativum. Optimization study by RSM recommended 1% concentration of stabilizer, antisolvent/solvent ratio of 15:1 and stirring time of 2hrs to formulate optimum nanosuspension of C. sativum. Under optimum conditions, nanosuspension of C. sativum with mean particle size 72.08 nm, polydispersity index 0.408 and zeta potential of 55 mV was successfully developed. Optimized nanosuspension showed almost 2.6 folds enhanced dissolution rate and greater plasma concentration of quercetin in nanosuspension administrated rats as compared to coarse suspension. AFM study demonstrated homogenous and narrow distribution of C. sativum nanoparticles with approximate size of 5–7 nm in height and 200–500 nm in width. It was concluded from the current research that fabrication of nanosuspension of C. sativum was an economical approach to increase its oral bioavailability.

Growth of Crystalline Bimetallic Metal-Organic Framework Films via Transmetalation.

Crystalline films of the Cu3(BTC)2 (BTC3- = 1,3,5-benzenetricarboxylate) metal-organic framework (MOF) have been grown by dip-coating an alumina/Si(111) substrate in solutions of Cu(II) acetate and the organic linker H3BTC. Atomic force microscopy (AFM) experiments demonstrate that the substrate is completely covered by the MOF film, while grazing incidence wide-angle X-ray scattering (GIWAXS) establishes the crystallinity of the films. Forty cycles of dip-coating results in a film that is ∼70 nm thick with a root mean squared roughness of 25 nm and crystallites ranging from 50-160 nm in height. Co2+ ions were exchanged into the MOF framework by immersing the Cu3(BTC)2 films in solutions of CoCl2. By varying the temperature and exchange times, different concentrations of Co were incorporated into the films, as determined by X-ray photoelectron spectroscopy experiments. AFM studies showed that morphologies of the bimetallic films were largely unchanged after transmetalation, and GIWAXS indicated that the bimetallic films retained their crystallinity.

Morphology and differentiation of human mesenchymal stem cells cultured on a nanoscale structured substrate

AbstractMesenchymal stem cell (MSC) is known to show responsiveness to the physical properties, such as stiffness and nano to microstructures, of the extracellular environment. However, the signaling mechanism has not been fully elucidated yet. Here, the effects of nanoscale pillar arrays of the cell culture substrate on morphology and differentiation were evaluated in human MSC to understand the signaling mechanism in regulation of differentiation in response to the nanoscale structures. Human MSCs were cultured on a quartz substrate with the three types of pillar‐arrays with 200 nm in side length, 150 nm in height, and different center‐to‐center spacings (300, 400, and 700 nm) in a cell culture medium with no differentiation induction regent. The cells were well spread, and about half of the cells showed osteogenic differentiation on the flat region of the substrate. The spreading and the osteogenic differentiation were suppressed in the cells on the pillar‐arrayed region regardless of the pillar spacing. This provided insight that the human MSCs spontaneously differentiate into the osteoblast in response to the stiff substrate with no structure, and the suppression of the cell spreading caused by the nanoscale structures can downregulate the progress of the osteogenic differentiation.

Nanoscale Characteristics of Ocular Lipid Thin Films Using Kelvin Probe Force Microscopy.

PurposeTo describe the use of Kelvin probe force microscopy (KPFM) to investigate the electrical surface potential of human meibum and to demonstrate successful use of this instrument on both human meibum and a meibum model system (six-lipid stock [6LS]) to elucidate nanoscale surface chemistry and self-assembly characteristics.Materials and Methods6LS and meibum were analyzed in this study. Mica-supported thin films were created using the Langmuir-Blodgett trough. Topography and electrical surface potential were quantified using simultaneous atomic force microscopy/KPFM imaging.ResultsBoth lipid mixtures formed thin film patches on the surface of the mica substrate, with large aggregates resting atop. The 6LS had aggregate heights ranging from 41 to 153 nm. The range in surface potential was 33.0 to 125.9 mV. The meibum thin films at P = 5 mN/m had aggregates of 170 to 459 nm in height and surface potential ranging from 15.9 to 76.1 mV, while thin films at P = 10 mN/m showed an aggregate size range of 147 to 407 nm and a surface potential range of 11.5 to 255.1 mV.ConclusionsThis study showed imaging of the differences in electrical surface potential of meibum via KPFM and showed similarities in nanoscale topography. 6LS was also successfully analyzed, showing the capabilities of this method for use in both in vitro and ex vivo ocular research.Translational RelevanceThis study describes the use of KPFM for the study of ocular surface lipids for the first time and outlines possibilities for future studies to be carried out using this concept.

Prospect of CW Raman Laser in Silicon- on- Insulator Nano-Waveguides


 Numerical analysis predicts that continuous-wave (CW) Raman lasing is possible in Silicon-On-insulator (SOI) nano-waveguides, despite of presence of free carrier absorption. The scope of this paper lies on lasers for communication systems around 1550 nm wavelength. Two types of waveguide structures Strip and Rib waveguides have been incorporated. The waveguide structures have designed to be 220 nm in height. Three different widths of (350, 450, 1000) nm were studied. The dependence of lasing of the SOI Raman laser on effective carrier lifetime was discussed, produced by tow photon absorption. At telecommunication wavelength of 1550 nm, Raman lasing threshold was calculated to be 1.7 mW in Rib SOI waveguide with dimensions width (W= 450 nm) and Length (L= 25 mm). The obtained Raman lasing is the lowest reported value at relatively high reflectivities. Raman laser in SOI nano-waveguides presents the important step towards integrated on-chip optoelectronic devices.

Lasing Action in Single Subwavelength Particles Supporting Supercavity Modes.

On-chip light sources are critical for the realization of fully integrated photonic circuitry. So far, semiconductor miniaturized lasers have been mainly limited to sizes on the order of a few microns. Further reduction of sizes is challenging fundamentally due to the associated radiative losses. While using plasmonic metals helps to reduce radiative losses and sizes, they also introduce Ohmic losses hindering real improvements. In this work, we show that, making use of quasibound states in the continuum, or supercavity modes, we circumvent these fundamental issues and realize one of the smallest purely semiconductor nanolasers thus far. Here, the nanolaser structure is based on a single semiconductor nanocylinder that intentionally takes advantage of the destructive interference between two supported optical modes, namely Fabry-Perot and Mie modes, to obtain a significant enhancement in the quality factor of the cavity. We experimentally demonstrate the concept and obtain optically pumped lasing action using GaAs at cryogenic temperatures. The optimal nanocylinder size is as small as 500 nm in diameter and only 330 nm in height with a lasing wavelength around 825 nm, corresponding to a size-to-wavelength ratio as low as 0.6.

Catalytic Behavior of Molybdenum Sulfide for the Hydrogen Evolution Reaction as a Function of Crystallinity and Particle Size Using Carbon Multiwall Nanotubes as Substrates

Abstract Molybdenum sulfide is of interest as a noble metal-free catalyst for the hydrogen evolution reaction (HER). In crystallized form, it shows a typical stacking of planar S–Mo–S layers whereas the catalytically active centers are situated on the edges of these entities characterized by non-saturated bonds of the molybdenum atoms. In this study, 2H-MoS2 is investigated as HER catalyst as a function of particle size using powder electrodes of different grain sizes and morphology. HER was also determined as a function of growth defects (bending of layers) and as a function of active sites employing MoS2 nanoparticles (NP). To study the influence of the substrate on the perfection of the transition metal disulfide, MoS2 nanosheets were deposited on multi-walled carbon nanotubes (MWCNTs) of different diameters. Highest activity was found for MoS2 nanosheets deposited on MWCNTs with a diameter smaller than 8 nm. At diameters larger than 10 nm, a wrapping of the nanotubes by partially bended stacks of S–Mo–S layers occurs, while at diameters smaller than 10 nm, individual MoS2 nanosheets of 3–5 S–Mo–S stacks of 3–4 nm in height and 10–20 nm in lateral extension surround the carbon nanotubes in form of hexagonal cylinders. The ratio of catalytically active non-van-der-Waals and hexagonal basal planes was determined electrochemically by electro-oxidation and correlated with HER activity.

3D Freestanding DNA Nanostructure Hybrid as a Low-Density High-Strength Material.

Structural DNA nanotechnology can produce a wide range of 3D nanostructures with programmable structure and size at <5 nm resolution. However, it is challenging to dry these structures without capillary force-induced damage. As a result, the applications of 3D DNA nanostructures have long been limited in aqueous environments. Ready access to free-standing 3D DNA nanostructures in the dry state could revolutionize many research areas, especially in the development of low-density, high-strength materials. Here we report a method to obtain free-standing wireframe 3D DNA tetrahedra in air on a solid substrate, such as SiO2 and mica, by absorbing uranyl acetate and lyophilization. The dried DNA tetrahedron structure, 93 ± 2 nm in height, withstands 42 ± 22 nN of loading force. The effective hardness (9.1 ± 5.1 MPa) and Young's modulus (77 ± 48 MPa) of this low-density (70.7 kg/m3) DNA-inorganic hybrid nanostructure are comparable to other reported low-density high-strength materials.

Flexible and highly ordered nanopillar electrochemical sensor for sensitive insulin evaluation

In line with growing interest in obesity management, there has been an increase in the amount of research focused on highly sensitive analysis systems for a small number of biomarers. In this paper, we introduce the highly ordered nanopillar electrode, featuring a high aspect ratio surface area that enables enhanced electron transfer. For fabrication of the flexible electrode, gold was evaporated by electronic beam lithography on polyurethane (PU), which has high flexibility. The fabricated nanopillar is 500 nm in diameter and 1500 nm in height. Based on the highly ordered nanostructure electrode, insulin was selected as a biomarker to monitor the insulin resistance associated with obesity. To effectively analyze the insulin, the self-assembled monolayer chemical was used to introduce the enzyme catalysis-based electrochemical immunoassay, leading to the analysis of the insulin concentration range from 0.1 to 1.0 ng/mL in the real sample. The square wave voltammetry principle was used to measure HRP-based electrochemical signal both electrochemically and quantitatively. Based on the nanostructural properties of significant electrochemical behavior, we successfully analyzed insulin in the plasma sample with high sensitivity (LOD of 0.1 ng/mL) and with high reproducibility (<10%). The obtained sensitivity of nanopillar electrode is approximately 10 times (1020%) greater than that of commercial electrode. The results demonstrated that the nanopillar electrode is suitable for precise and sensitive analysis of low-level biomolecules in medical and commercial fields.

Direct Measurement of Plant Cellulose Microfibril and Bundles in Native Cell Walls.

Plants use rigid cellulose together with non-cellulosic matrix polymers to build cell walls. Cellulose microfibrils comprise linear β(1,4)-glucan chains packed through inter- and intra-chain hydrogen-bonding networks and van der Waals forces. Due to its small size, the number of glucan chains and their arrangement in a microfibril remains elusive. Here we used atomic force microscopy (AFM) to directly image primary cell walls (PCWs) and secondary cell walls (SCWs) from fresh tissues of maize (Zea mays) under near-native conditions. By analyzing cellulose structure in different types of cell walls, we were able to measure the individual microfibrils in elongated PCWs at the sub-nanometer scale. The dimension of the microfibril was measured at 3.68 ± 0.13 nm in width and 2.25 ± 0.10 nm in height. By superimposing multiple AFM height profiles of these microfibrils, the overlay area representing the cross-section was estimated at 5.6 ± 0.4 nm2, which fitted well to an 18-chain model packed as six sheets with 234432 conformation. Interestingly we found in PCW, all these individual microfibrils could be traced back to a bundle in larger imaging area, suggesting cellulose are synthesized as large bundles in PCWs, and then split during cell expansion or elongation. In SCWs where cell growth has ceased we observed nearly-parallel twined or individual microfibrils that appeared to be embedded separately in the matrix polymers without the splitting effect, indicating different mechanisms of cellulose biosynthesis in PCW and SCW. The sub-nanometer structure of the microfibril presented here was measured exclusively from elongated PCWs, further study is required to verify if it represents the inherent structure synthesized by the cellulose synthase complex in PCWs and SCWs.

Excitation-Independent Blue-Emitting Carbon Dots from Mesoporous Aminosilica Nanoreactor for Bioanalytical Application

Here we present the first example of excitation-independent blue-emitting carbon dots (iC-dots) obtained by pyrolysis of citric acid (CA) without post-treatment chromatographic separation. To confine the growth and shape of carbon nanoparticles, silica gel with immobilized aminopropyl groups (SiO2–NH2) was used as a nanoreactor. It was demonstrated that the carbonization of SiO2–NH2 with embedded CA resulted in the formation of unbound wC-dots and immobilized iC-dots. Because of their firm attachment to the surface, iC-dots can be easily separated from low-molecular impurities and wC-dots by simply rinsing the nanocomposite with water. From atomic force and transmission electron microscopies iC-dots can be represented as flattened spheroids with 2–4 nm of height and 5 nm in lateral size. The size distribution profile for wC-dots is very wide with about 95% the particles within the 2.5–5.5 nm size range. Increasing the template pore size from 4.9 up to 9.1 nm has no effect on the size of the iC-dots. From Fourier transform infrared analysis and X-ray photoelectron spectroscopy data it was assumed that iC-dots belong to N-doped C-nanoparticles with 9:1 carbon to nitrogen atomic ratio. As-prepared iC-dots demonstrate excitation-independent photoluminescence at 445 nm with quantum yields up to 16.8%, which makes them attractive for bioanalytical application.

Increasing the Interferogram Sensitivity by Digital Holography

This paper presents the results of experimental studies and digital methods for recording of holograms using spatial light modulators. The use of holographic interference methods for measuring nanoscale irregularities is described for the case of a nanostep (70 nm in height and 30 $$\mu$$ m in width). Examples are given of the method of increased sensitivity for nanostep measurements and the method of hooks using a digital technique. Correction of internal system distortions in the interferometer has been shown to be a workable method. The holographic interference methods with digital processing of holograms allows the sensitivity of interferograms to be increased without loss of basic information about the object and without increasing the measurement accuracy.

Numerical Analysis of CW Raman Amplifier in Silicon-on-Insulator Nano-Waveguides

Numerical analysis of continuous wave (CW) on-off optical Raman gain in Silicon-On-insulator (SOI) nano-waveguides has been investigated. Two types of waveguide structures rib and strip waveguides have been incorporated. The waveguide structures have designed to be 220 nm in height. Three different widths of (350, 450, 1000) nm were studied. At telecommunication wavelength of 1550 nm, Raman amplification was calculated to be about 65 dB in rib SOI waveguide. The obtained Raman amplification is the heist reported value at relatively low pump power. High Raman gain amplification in SOI nano-waveguides presents an important step towards integrated on-chip optoelectronic devices.

Inkjet-printed electrochemically reduced graphene oxide microelectrode as a platform for HT-2 mycotoxin immunoenzymatic biosensing

The design and application of an inkjet-printed electrochemically reduced graphene oxide microelectrode for HT-2 mycotoxin immunoenzymatic biosensing is reported. A water-based graphene oxide ink was first formulated and single-drop line working microelectrodes were inkjet-printed onto poly(ethylene 2,6-naphthalate) substrates, with dimensions of 78 μm in width and 30 nm in height after solvent evaporation. The printed graphene oxide microelectrodes were electrochemically reduced and characterized by Raman and X-ray photoelectron spectroscopies in addition to microscopies. Through optimization of the electrochemical reduction parameters, differential pulse voltammetry were performed to examine the sensing of 1-naphthol (1-N), where it was revealed that reduction times had significant effects on electrode performance. The developed microelectrodes were then used as an immunoenzymatic biosensor for the detection of HT-2 mycotoxin based on carbodiimide linking of the microelectrode surface and HT-2 toxin antigen binding fragment of antibody (anti-HT2 (10) Fab). The HT-2 toxin and anti-HT2 (10) Fab reaction was reported by anti-HT2 immune complex single-chain variable fragment of antibody fused with alkaline phosphatase (anti-IC-HT2 scFv-ALP) which is able to produce an electroactive reporter – 1-N. The biosensor showed detection limit of 1.6 ng ∙ mL−1 and a linear dynamic range of 6.3 – 100.0 ng ∙ mL−1 within a 5 min incubation with 1-naphthyl phosphate (1-NP) substrate.