Small Nano Research Articles

Nanoindentation simulation on single crystal copper by quasi-continuum method

Considering that nanoindentation size effect under very small nano scale could not be effectively investigated by traditional experimental methods, this paper proposed to use quasi-continuum (QC) method to establish a multi-scale simulation model for nanoindentation process on single crystal copper at very small depth, below 20Å. And different-size small indenters were adopted in this paper with their radiuses ranging from 2nm to 10nm. The simulation results showed that the contact stiffness did not show indentation size effect, but the values fluctuated on a horizontal line; that the nano-hardness showed obvious indentation size effect.

Invited review: Fluctuation-induced transport. From the very small to the very large scales

The study of fluctuation-induced transport is concerned with the directed motion of particles on a substrate when subjected to a fluctuating external field. Work over the last two decades provides now precise clues on how the average transport depends on three fundamental aspects: the shape of the substrate, the correlations of the fluctuations and the mass, geometry, interaction and density of the particles. These three aspects, reviewed here, acquire additional relevance because the same notions apply to a bewildering variety of problems at very different scales, from the small nano or micro-scale, where thermal fluctuations effects dominate, up to very large scales including ubiquitous cooperative phenomena in granular materials. Received: 30 October 2015, Accepted: 4 February 2016; Edited by: G. Martínez Mekler; Reviewed by: J. Mateos, Departamento de Sistemas Complejos, Instituto de Física, Universidad Nacional Autónoma de México, México.; DOI: http://dx.doi.org/10.4279/PIP.080004Cite as: G P Suárez, M Hoyuelos, D R Chialvo, Papers in Physics 8, 080004 (2016)This paper, by G P Suárez, M Hoyuelos, D R Chialvo, is licensed under the Creative Commons Attribution License 3.0.

Cancer Theranostic Nanoparticles Self-Assembled from Amphiphilic Small Molecules with Equilibrium Shift-Induced Renal Clearance.

Nano drug delivery systems have emerged as promising candidates for cancer therapy, whereas their uncertainly complete elimination from the body within specific timescales restricts their clinical translation. Compared with hepatic clearance of nanoparticles, renal excretion of small molecules is preferred to minimize the agent-induced toxicity. Herein, we construct in vivo renal-clearable nanoparticles, which are self-assembled from amphiphilic small molecules holding the capabilities of magnetic resonance imaging (MRI) and chemotherapy. The assembled nanoparticles can accumulate in tumor tissues for their nano-characteristics, while the small molecules dismantled from the nanoparticles can be efficiently cleared by kidneys. The renal-clearable nanoparticles exhibit excellent tumor-inhibition performance as well as low side effects and negligible chronic toxicity. These results demonstrate a potential strategy for small molecular nano drug delivery systems with obvious anticancer effect and low-toxic metabolism pathway for clinical applications.

TEM and SEM study of nano SiO2 particles exposed to influence of neutron flux

Before and after neutron irradiation, in order to identify the “adhesion” in silica nanoparticles, analyses have been conducted on transmission electron microscope (TEM) at small nano dimensions. Simultaneously, at relatively larger nano dimensions, the surfaces of the samples were observed by the scanning electron microscope (SEM). Moreover, analyses of the samples with SAED (selected area electron diffraction) technology on TEM device used for determining the structure of the nanomaterial. From TEM analyses, it has been found that little “adhesion” is observed at small dimensions (maximum 70nm) under the influence of neutron irradiation and this “adhesion” directly influences the electrophysical properties of nanomaterials.

A new approach for modelling lattice energy in finite crystal domains

Evaluation of internal energy in a crystal lattice requires precise calculation of lattice sums. Such evaluation is a problem in the case of small (nano) particles because the traditional methods are usually effective only for infinite lattices and are adapted to certain specific potentials. In this work, a new method has been developed for calculation of lattice energy. The method is a generalisation of conventional geometric probability techniques for arbitrary fixed lattices in a finite crystal domain. In our model, the lattice energy for wide range of two- body central interaction potentials (including long-range Coulomb potential) has been constructed using absolutely convergent sums. No artificial cut-off potential or periodical extension of the domain (which usually involved for such calculations) have been made for calculation of the lattice energy under this approach. To exemplify the applications of these techniques, the energy of Coulomb potential has been plotted as the function of the domain size.

New Revolutionary Ideas of Material Processing – A Path to Biomaterial Fabrication by Rapid Prototyping

The fundamentally different features of Rapid prototyping (RP) from that of conventional sintering offerus some new approaches to develop materials with excellent properties. Applying this method, porous Hydroxyapatite (Hap) ceramics, as well as the HAp-zirconia composites have been fabricated successfully. Porous hydroxyapatite (Hap) is expected to have desired mechanical and biological properties for biomedical applications. However, due to material processing problems, to date, this material can only be prepared by conventional techniques. Fuse deposition Machine is modified to fabricate Hap conventional support structure is not required three nozzle system is utilized for fabrication. Main nozzle is provided with heating arrangement. Two nozzles provided for transient Hap and solvent. Three stages heating with two lasers arrangement for gradual temperature change so transformation is faster .Primary result shows mechanical properties and porosity is as per bone structure. The micro structural characterizations such as phase purity and composition of porous BCP granules were performed and verified by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analysis. The chemical and the microstructure information of the Fabricated Hap were investigated by FT-IR (Fourier Transform Infra-Red), SEM (Scanning Electron Microscopy), X-ray Diffraction (XRD). Result shows interconnected regular pores and uniformly distribution of Hap. There is covalent boding makes stronger adhesion to prosthetic. Using this technique, it is possible to produce scaffolds with mechanical and structural properties close to those of the natural bone and teeth. The prepared scaffold has an open, regular pattern and uniformly interconnected porous structure. Some extent problem of small Nano particle aggregate together is called Balling and product of different temperature solidify on the layer is called recasting is dominates the process. By optimizing the operating parameter these problem can be minimized.

Binary optimization of gold nano-rods for designing an optical modulator

An optical modulator with ultra small plasmonic nano rods that can filter the coherent optical frequency is developed. The performance of optical modulator based on dimmer metal nano rods on the top of silicon waveguides as coherent perfect absorber (CPA) is studied. In the proposed model, the optical modulator is excited by two monochromatic incident plan waves with the same frequencies and two polar angles "$$\uptheta =0$$?=0" and "$$\uptheta =\Pi /2$$?=?/2". When the signal with $$\uptheta =0$$?=0 is applied to the modulator separately, the incident wave transmits from the first path and suppresses for the second one, while when both signals are applied to the modulator simultaneously, the CPA occurs for the first path and the ligthwave transmits from the second one. Therefore for two paths there are two states. "on" state when ligthwave transmitted from each path and "off" state when ligthwave suppressed. In this case two paths consist of different array of nano rods locations. Since the CPA efficiency depends strongly on the number of plasmonic nano rods and the nano rods location, a new efficient binary optimization method based the teaching---learning-based optimization (TLBO) algorithm is proposed to design an optimized array of the plasmonic nano-rods in order to achieve the maximum absorption coefficient in the `off' state and the minimum absorption coefficient in the `on' state. In Binary TLBO, a group of learner consists a matrix with binary entries, control the presence (`1') or the absence (`0') of nano rods in the array.

Nanocrystal technology for drug formulation and delivery

With the development of modern technology like high throughput screening, combinatorial chemistry and computer aid drug design, the drug discovery process has been dramatically accelerated. However, new drug candidates often exhibit poor aqueous or even organic medium solubility. Additionally, many of them may have low dissolution velocity and low oral bioavailability. Nanocrystal formulation sheds new light on advanced drug development. Due to small (nano- or micro- meters) sizes, the increased surface-volume ratio leads to dramatically enhanced drug dissolution velocity and saturation solubility. The simplicity in preparation and the potential for various administration routes allow drug nanocrystals to be a novel drug delivery system for specific diseases (i.e. cancer). In addition to the comprehensive review of different technologies and methods in drug nanocrystal preparation, suspension, and stabilization, we will also compare nano- and micro-sized drug crystals in pharmaceutical applications and discuss current nanocrystal drugs on the market and their limitations.

Self-assembly of strongly dipolar molecules on metal surfaces.

The role of dipole-dipole interactions in the self-assembly of dipolar organic molecules on surfaces is investigated. As a model system, strongly dipolar model molecules, p-benzoquinonemonoimine zwitterions (ZI) of type C6H2(⋯ NHR)2(⋯ O)2 on crystalline coinage metal surfaces were investigated with scanning tunneling microscopy and first principles calculations. Depending on the substrate, the molecules assemble into small clusters, nano gratings, and stripes, as well as in two-dimensional islands. The alignment of the molecular dipoles in those assemblies only rarely assumes the lowest electrostatic energy configuration. Based on calculations of the electrostatic energy for various experimentally observed molecular arrangements and under consideration of computed dipole moments of adsorbed molecules, the electrostatic energy minimization is ruled out as the driving force in the self-assembly. The structures observed are mainly the result of a competition between chemical interactions and substrate effects. The substrate's role in the self-assembly is to (i) reduce and realign the molecular dipole through charge donation and back donation involving both the molecular HOMO and LUMO, (ii) dictate the epitaxial orientation of the adsorbates, specifically so on Cu(111), and (iii) inhibit attractive forces between neighboring chains in the system ZI/Cu(111), which results in regularly spaced molecular gratings.

Experimental investigation on structural and optical properties of ZnO: AZO nano particles by hydrothermal synthesis

The undoped and Al-doped ZnO (AZO) nanostructures were synthesized by using simple hydrothermal process with two different pH values 6 and 10. The structural and optical properties of the ZnO and 0.5 % AZO nano particles were investigated using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscope, atomic force microscope, X-ray diffraction (XRD), Ultraviolet–visible (UV) spectroscopy and photoluminescence (PL). It is observed from XRD results; on aluminium doping the crystalline size reduces significantly. It can be clearly seen from the FESEM images that Al doping causes the crystalline structure of ZnO to agglomerated small grain nano particles and TEM confirms that the particles are of nanometer size. The UV absorption indicates that blue shift of the samples increases the optical band gap, and decreases the average crystallite size. In the PL spectra, undoped ZnO exhibit an excitonic peak in the UV region and a defect-related peak in the visible region, whereas Al doping leads to a suppression of c lattice parameter and blue shift of luminescence with blue and green emission.

English

Technology is shrinking quantity wise, increasing quality wise at a rather rapid rate. As a result, more and more advancements are taking place at the cellular, molecular and atomic level — at the nanoscale. NANOTECHNOLOGY: Is especially important to medicine because the medical field deals with things on the smallest of levels. Additionally, the small nano devices that are being developed right now can enter the body and treat and prevent diseases. NANOMEDICINE: Is the application of nanotechnology (the engineering of tiny machines) for the prevention and treatment of disease in the human body. This evolving discipline has the potential to dramatically change medical science. NANOBOTS: Smallest of robots could be used to perform a number of functions inside the body and out. They could even be programmed to build other nanobots. NANOCOMPUTERS: To direct nanobots in their work, there are special computers. NANOTWEEZERS: devices are designed to manipulate nanostructures. Nanotweezers are usually constructed using nanotubes. NANOCHIP: Is an integrated circuit that is so small, in physical terms, that individual particles of matter play

Formation of Nanostructures in Severely Deformed High-Strength Steel Induced by High-Frequency Ultrasonic Impact Treatment

Surface modification by the generation of a nanostructured surface layer induced via ultrasonic impact treatment was performed at the weld toe of a welded high-strength quenched and tempered structural steel, S690QL1 (Fe-0.16C-0.2Si-0.87Mn-0.33Cr-0.21Mo (wt pct)). Such high-frequency peening techniques are known to improve the fatigue life of welded components. The nanocrystallized structure as a function of depth from the top-treated surface was characterized via a recently developed automated crystal orientation mapping in transmission electron microscopy. Based on the experimental observations, a grain refinement mechanism induced by plastic deformation during the ultrasonic impact treatment is proposed. It involves the formation of low-angle misoriented lamellae displaying a high density of dislocations followed by the subdivision of microbands into blocks and the resulting formation of polygonal submicronic grains. These submicronic grains further breakdown into nano grains. The results show the presence of retained austenite even after severe surface plastic deformation. The average grain size of the retained austenite and martensite is $$\sim $$ 17 and $$\sim $$ 35 nm, respectively. The in-grain deformation mechanisms are different in larger and smaller grains. Larger grains show long-range lattice rotations, while smaller grains show plastic deformation through grain rotation. Also the smaller nano grains exhibit the presence of short-range disorder. Surface nanocrystallization also leads to an increased fraction of low angle and low energy coincident site lattice boundaries especially in the smaller grains ( $$D<50$$ nm).

Solvothermal synthesis of nanocrystalline ZnO with excellent photocatalytic performance

We reported a facile way to synthesize nanocrystalline ZnO particles with excellent photocatalytic performance. Their microstructures and optical properties were characterized by X-ray diffraction, field emission scanning electron, transmission electron microscopy, photoluminescence spectra and ultraviolet–visible (UV–Vis) spectra. Photocatalytic tests showed the as-prepared ZnO particles had a good activity for photodegradation of organic dyes under UV–Vis light irradiation, which was comparable with that of P25 TiO2, a commercial standard photocatalyst. Furthermore, the sample could be easily sedimentary from the reaction system, which was favorable for the separation and reuse. Meanwhile, the photocatalytic performance of the samples exhibited no obvious reduction in the activity after five recycles of photodegradation, demonstrating its superior reusability. We attributed the superior performance to the efficient synergistic effect resulted from the small nano size, as well as the appropriate oxygen vacancies in the ZnO lattice. Our work might be promising for the application of ZnO-based photocatalysts due to its low cost, easy process, and good performance.

Low-Temperature Growth and Properties of NiO Nano Sheets Decorated with Small NiO Nano Rods via Soft Chemical Process

Low-Temperature Growth and Properties of NiO Nano Sheets Decorated with Small NiO Nano Rods via Soft Chemical Process

Large contribution of small phytoplankton at Marian Cove, King George Island, Antarctica, based on long-term monitoring from 1996 to 2008

To detect and monitor coastal marine ecosystem responses to current environmental changes, the phytoplankton assemblage, salinity, and macro-nutrients were monitored daily at a fixed coastal site in Marian Cove, Antarctica, from 1996 to 2008. The monthly average water temperature at the site was highest (2.14 ± 0.36 °C) during the summer period (December–February) and lowest (−1.80 ± 0.22 °C) during the winter period (July–September). The salinity levels exhibited the opposite trend with the lowest values (30.9 ± 0.68 psu) during summer and the highest values (35.2 ± 1.15 psu) during winter. The concentrations of major nutrients were always high enough for phytoplankton growth, indicating the nutrients are not a main controlling factor for phytoplankton growth. Total chlorophyll-a generally started to increase from late November with a peak (1.14 ± 1.41 mg chl-a m−3) around January when the water temperature was the warmest during the year. Within the phytoplankton communities, the average contribution of small (nano- plus pico-) phytoplankton (<20 μm) to the total chl-a concentration was high (62.9 %) throughout the study period, which supports the observation that small phytoplankton contributed 85.7 % to the cell numbers and 56.4 % to the biovolume of the total phytoplankton. The high contribution of small phytoplankton is a general characteristic at Marian Cove and may be expected to increase under future warming conditions.

Optical Properties of the Chalcogenide-Multi Walled Carbon Nano Tubes and Chalcogenide-Graphene Composite Materials

Physical property variation due to incorporation of organic content into the inorganic chalcogenide alloy configuration might be an interesting topic for the investigation. Predominantly structural and optical properties can define their utility for the different uses. Therefore, this work demonstrates the microstructure as well as UV/Visible optical parameters, like, absorption spectra, extinction coefficient (k), real dielectric constant (� � ), imaginary dielectric constant (� �� ), refractive index (n), absorption coefficient (� ) and optical energy band gap for the Se96Zn2Sb2 composition alloy as well as Se96Zn2Sb2 + 0.05% multi walled carbon nano tubes and Se96Zn2Sb2 + 0.05% bilayer graphene composite materials. Experimental evidences have demonstrated that materials structural and optical properties altered due to incorporation of small amounts multi walled carbon nano tubes and bilayer graphene in Se96Zn2Sb2 configuration. The materials structural and optical properties changes could be interpreted with the help of the bond formation mechanism in the solids.

Carbon nanodots from date molasses: new nanolights for the in vitro scavenging of reactive oxygen species.

Most of the nanoimaging tools like quantum dots and metallic nanoparticles are shown to have different levels of cytotoxicity via various mechanisms. However carbon nanodots (CNDs) are a new group of ultra small nano structures (average 4-6 nm) which is potential candidate of next generation optical imaging. Being carbonaceous in origin, CNDs possess excellent luminescence and photostability with significantly less cytotoxicity. In present study, we have synthesized carbon nano-dots from date molasses by microwave irradiation at ∼pH 11. The synthesized carbon nanodots were characterized using UV-Vis spectroscopy, fluorescence spectroscopy, TEM, XRD analysis, FTIR study and Zeta potential measurement. The average sizes of the dots were found to be 5-7 nm. A clear band emission was visible around 480 nm when an excitation beam of 415 nm was incident. For biological applicability, MTT assay and hemocompatibility studies were performed. The results exhibited the material to be highly cytocompatible within the application limit. Upon immediate exposure to CNDs, no significant changes to cellular surface morphology were observed via AFM imaging. Significant hemolysis or blood cell aggregation was not observed after incubation of CNDs with blood. After labelling with CNDs, MG-63 cells were found to be unbleached up to several hours even on exposure to light. We are reporting first time in this study the free radical scavenging property of CNDs in ex vivo and in vitro models. Antioxidant activity was measured ex vivo via potassium permanganate assay and DPPH assay. In vitro superoxide inhibition activity was measured both by spectroscopy and under microscope by NBT reduction assay. Hydroxyl free radical inhibition activity was measured via DCFH-DA Assay. The results were comparable with scavenging activity of standard antioxidant molecules (BHT and l-ascorbic acid). A novel assay for quantitative analysis of cellular oxidative stress was also proposed. Therefore, this material could be useful for long-term live cell imaging and cell tracking in a scaffold with minimal cytotoxicity and oxidative stress.

Springtime phytoplankton dynamics in Arctic Krossfjorden and Kongsfjorden (Spitsbergen) as a function of glacier proximity

Abstract. The hydrographic properties of the Kongsfjorden–Krossfjorden system (79° N, Spitsbergen) are affected by Atlantic water incursions as well as glacier meltwater runoff. This results in strong physical gradients (temperature, salinity and irradiance) within the fjords. Here, we tested the hypothesis that glaciers affect phytoplankton dynamics as early as the productive spring bloom period. During two campaigns in 2007 (late spring) and 2008 (early spring) we studied hydrographic characteristics and phytoplankton variability along two transects in both fjords, using high-performance liquid chromatography (HPLC)-CHEMTAX pigment fingerprinting, molecular fingerprinting (denaturing gradient gel electrophoresis, or DGGE) and sequencing of 18S rRNA genes. The sheltered inner fjord locations remained colder during spring as opposed to the outer locations. Vertical light attenuation coefficients increased from early spring onwards, at all locations, but in particular at the inner locations. In late spring meltwater input caused stratification of surface waters in both fjords. The inner fjord locations were characterized by overall lower phytoplankton biomass. Furthermore HPLC-CHEMTAX data revealed that diatoms and Phaeocystis sp. were replaced by small nano- and picophytoplankton during late spring, coinciding with low nutrient availability. The innermost stations showed higher relative abundances of nano- and picophytoplankton throughout, notably of cyanophytes and cryptophytes. Molecular fingerprinting revealed a high similarity between inner fjord samples from early spring and late spring samples from all locations, while outer samples from early spring clustered separately. We conclude that glacier influence, mediated by early meltwater input, modifies phytoplankton biomass and composition already during the spring bloom period, in favor of low biomass and small cell size communities. This may affect higher trophic levels especially when regional warming further increases the period and volume of meltwater.

Nano crystalline high energy milled 5083 Al powder deposited using cold spray

• NC non-cryomilled Al alloy powder produced by high-energy milling technique. • Nanocrystalline structure of the powder is retained after cold spraying. • No change in nanohardness between the powder and the cold sprayed layer. • Little evidence of dislocations within the nanograins of the cold sprayed layer. Electron microscopy and nanoindentation are used to investigate the relationship between microstructure and nanohardness of a non-cryomilled, nanocrystalline 5083 Al alloy powder before and after being deposited by cold spray. Microstructural investigations observed the presence of nano grains in the powder microstructure, ranging from 20 to 80 nm and with a typical grain size of 40–50 nm. It was also revealed that the nanocrystalline structure of the powder is retained after cold spraying. As a result, almost no change in nanohardness was indicated between the powder and the particles interior in the cold sprayed layer. However, hardness was substantially higher in some regions in the cold sprayed layer, which was attributed to the particle–particle interfaces or other areas with very small nano grain size. The presence of some un-joined particle remnant lines was also found in the deposition and explained through Critical Velocity Ratio (CVR) of powder particles. Although cold spray is a high deformation process, there is little evidence of dislocations within the nanograins of the cold sprayed layer. The latter observation is rationalized through intragranular dislocation slip and recovery mechanisms.

Study of temperature and size dependent elastic constant of LiNbO3 nano particles embedded in Al-metal matrix

In the present communication, temperature dependent elastic constant related to Debye temperature have been studied in LiNbO3 nano-particle embedded in Al-matrix. The size of the embedded material is considered in nano range. The nanoparticles of LiNbO3 were synthesized from chemical precipitation methods. LiNbO3 possesses hcp (hexagonal closed packing) crystal structure. Ultrasonic velocity, Grneisen parameter and acoustic coupling constant that depend on the second and third order elastic constants which are used for the determination of ultrasonic attenuation coefficient. The second and third order elastic constant were computed from deformation theory. The Debye temperature depends upon the size of the material. The change in Debye temperature was found to be maximum in smaller size particles. But it is decreased with increasing the size of the nano-particles. This is due to change in thermal expansion coefficients. The elastic constant also changes with changing the size of the nano particles. Smaller nano particles show large elastic constant but it decreases with increasing the sizes of the particles. Debye temperature not only changes by the size of the materials but also causes to change in elastic constant. The second and third elastic constants show the opposite relation with the temperature.