Self-assembled germanium nano-structures by laser-assisted oxidation

The investigation on the oxidation behaviour of Si1-xGex alloys （x=0.05, 0.15, and 0.25） is carried out. It is found for the first time that on the oxide film a germanium nano-cap with a thickness of 1.8-2.8nm and a few Ge nanoparticles with diameters ranging from 5.5 nm to 10 nm are formed by the low-temperatu.re laser-assisted dry oxidation of Si1-xGex substrate. A new scanning method on the decline cross-section of the multiple-layer sample is adopted to measure the layer thickness and the composition. Some new peaks in photoluminescence （PL） spectra are discovered, which could be related to the nano-cap and the nano-particles of germanium. A suitable model and several new calculating formulae with the unrestricted Hartree-Fock-Roothaan （UHFR） method and quantum confinement analysis are proposed to interpret the PL spectra and the nano-structure mechanism in the oxide.

Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hi- erarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching （EE）. MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched （SEA） as well as Machined （M） surfaces respectively. The results show signifi- cant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

Preparation and Characterization of Nano-Structured SiO_(2) Thin Films on Carbon Steel

Nano-structured SiO2 thin films were prepared on the surface of carbon steel for the first time by LPD. The compositions of the films were analyzed by XPS, and the surface morphology of the thin films were observed by AFM. The thin films were constituted by compact particles of SiO2, and there was no Fe in the films. In the process of film forming, the SiO2 colloid particles were deposited or absorbed directly onto the surface of carbon steel substrates that were activated by acid solution containing inhibitor, and corrosion of the substrates was avoided. The nano-structured SiO2 thin films that were prepared had excellent protective efficiency to the carbon steel.

Electron emission degradation of nano-structured sp^2-bonded amorphous carbon films

The initial field electron emission degradation behaviour of original nano-structured sp^2-bonded amorphous carbon films has been observed, which can be attributed to the increase of the work function of the film in the field emission process analysed using a Fowler-Nordheim plot. The possible reason for the change of work function is suggested to be the desorption of hydrogen from the original hydrogen termination film surface due to field emission current-induced local heating. For the explanation of the emission degradation behaviour of the nano-structured sp2-bonded amorphous carbon film, a cluster model with a series of graphite （0001） basal surfaces has been presented, and the theoretical calculations have been performed to investigate work functions of graphite （0001） surfaces with different hydrogen atom and ion chemisorption sites by using first principles method based on density functional theory-local density approximation.

One-dimensional nano-structure of Cu-Zn-Al alloy

Cu-Zn-Al alloy of one dimensional nano-structure was prepared and thestructure of obtained nano-material was characterized by transmission electron microscope (TEM). Itwas shown that there are non-linear oscillations on the surface of Cu-Zn-Al alloy and theconsanguineous connection exists between non-linear oscillation and the growth process of onedimensional nano-structure. The diameter of one dimensional nano-structure is about 40 nm, and theratio of length to diameter is over 40. Finally, the growth mechanism of one dimensionalnano-structure was also studied.

Nano-Structure Observed in Highly Doped Silicon Crystalline

It was reported that due to the non-linear electrical phenomena,the super-saturated arsenic in silicon single crystalline precipitates during post processing at low temperatures to form different structures.The structure with spatial period of 1.7 to 2.3 nm was observed firstly by TEM on the sample.

Cobalt supported on CNTs-covered γ-and nano-structured alumina catalysts utilized for wax selective Fischer-Tropsch synthesis

Cobalt supported on carbon nanotubes （CNTs）-covered alumina has been recently developed and successfully utilized as a catalyst in Fischer-Tropsch synthesis （FTS）. Problems associated with shaping of Co/CNTs into extrudates or pellets as well as catalyst attrition rendered these materials unfavorable for industrial applications. In this investigation regular γ- and nano-structured （N-S） alumina as well as CNTs-covered regular γ- and N-S-alumina supports were impregnated by cobalt nitrate solution to make new cobalt-based catalysts which were also promoted by Ru. The catalysts were characterized and tested in a micro reactor to evaluate their applicability in FTS. γ-Al2O3 was prepared by calcination of bohemite and N-S-Al2O3 was prepared by sol-gel method using aluminum chloride as starting material. Catalyst evaluations indicated that N-S-Al2O3 was superior to regular γ-Al2O3 and that CNTs-covered alumina supports were favored over non-covered ones in terms of activity and heavy hydrocarbon selectivity. These were justified by porosimetric characteristics of the catalysts and existence of CNTs points of view. CNTs-covered catalysts also showed higher wax selectivity and better resistance to deactivation. Furthermore, TPR analysis indicated that the cobalt aluminate phase, which is responsible for the permanent deactivation of alumina supported Co-based catalysts, did not form on alumina supported Co-based catalysts covered with CNTs due to weaker interactions between cobalt and alumina.

Deposition mechanism of nano-structured single-layered C_(36) film on a diamond (100) crystal plane

The Brenner-LJ potential is adopted to describe the interaction between C36 clusters and diamond surface, and the deposition mechanism of multi-C36 clusters on the diamond surface is also studied by using the method of molecular dynamics simulation. The simulation results show that the competition effects of two interactions, i.e. the interaction between cluster and cluster and the interaction between cluster and crystal plane, are studied, and then the influence of these competition effects on C36 cluster deposition is analysed. The finding is that when an incident energy is appropriately chosen, C36 clusters can be chemically adsorbed and deposited steadily on the diamond surface in the form of single-layer, and in the deposition process the multi-C36 clusters present a phenomenon of energy transmission. The experimental result shows that at a temperature of 300K, in order to deposit C36 clusters into a steady nanostructured single-layered film, the optimal incident energy is between 10 and 18 eV, if the incident energy is larger than 18 eV, the C36 clusters will be deposited into an island nano-structured film.

Analysis of the Carbon Nano-Structures Formation in Liquid Arcing

Graphite electrodes were used for the direct current （DC） arc discharge in water. And high-resolution transmission electron microscopy （HRTEM） was used to investigate the products. Based on the experimental phenomena and nano-structure products, arc plasma characteristics in water were analyzed theoretically. Two growth regions and relevant growth modes were proposed to interpret the formation mechanisms of nano-structures by arc discharge in water. Furthermore, liquid nitrogen and cross magnetic field was applied to change the arcing state respectively, and new carbon nano-structures were obtained. Their formation mechanisms were also analyzed correspondingly.

Research on the field emission mechanism of nano-structured carbon film

The field emission （FE） characteristics of nano-structured carbon films （NSCFs） are investigated. The saturation behaviour of the field emission current density found at high electric field E cannot be reasonably explained by the traditional Fowler-Nordheim （F-N） theory. A three-region E model and the curve-fitting method are utilized for discussing the FE characteristics of NSCFs. In the low, high, and middle E regions, the FE mechanism is reasonably explained by a modified F-N model, a corrected space-charge-limited-current （SCLC） model and the joint model of F N and SCLC mechanism, respectively. Moreover, the measured FE data accord well with the results from our corrected theoretical model.

The 18.3% Silicon Solar Cells with Nano-Structured Surface and Rear Emitter

A nano-structured surface is formed on the pyramid structure of n-type silicon solar cells by size-controlled silver nano-particle assisted etching. Such a nano-structure creates a front average weighted reflectance of less than 2.5% in the 300-1200nm range due to the broadband reflection suppression. The sodium hydroxide is used to obtain the low-area surface by post-etching the nano-structure, thus the severe carrier recombination associated with the nano-structured surface could be reduced. After emitter forming, screen printing and firing by means of the industrial fabrication protocol, an 18.3%-efficient nano-structured silicon solar cell with rear emitter is fabricated. The process of fabricating the solar cells matches well with industrial manufacture and shows promising prospects.

Enhancing Mechanical Stability of Nano-Structured Anti-Reflection Coatings

Periodic Nanostructured anti-reflection coatings (NALs) are a promising option for enhancing transmission of coherent light without inducing scattering. We’ve found that reducing the height of NALs below a critical value to enhance mechanical stability can highly reduce the transmission efficiency. Here, using Rigorous Couples Wave Analysis (RCWA), we find the minimum height for over 99% transmission and effect of height on transmission bandwidth. Then, during a one-step plasma etching, two samples with different heights have been generated and their efficiency is evaluated using RCWA.

Comparative Assessment on Machinability of Nano-Structured Bainitic Steel and Titanium64

Titanium64 has characteristics well sought after for applications in demanding environments. In general, due to titanium64’s high performance, it is a material which requires careful and well considered machining approaches in order to optimize the process. Nano-structured bainitic steel whilst having different application bases does none the less have similar machining and machinability short comes as that of titanium64. These similar characteristics have been compared and contrasted in this research study using parameters including cutting force, surface texture and metallography. The results tend to indicate that titanium64 has a poorer machinability characteristics compared to nano-structured bainitic steel. However, in terms of achieving greater surface texture characteristics, the nano-structured bainitic steel exhibited an enhanced capacity.

A Comparative Study on the Milling Speed for the Synthesis of Nano-Structured Al 6063 Alloy Powder by Mechanical Alloying

The present article reports on characterization studies performed on amorphized nanostructured Al 6063 alloy powder synthesized by mechanical alloying (MA). The as-milled powder was characterized by X-ray diffraction (XRD) for investigating the development of crystallite nature and determining the different phases of the materials present, scanning electron microscope (SEM) was used for in depth morphological study and High Resolution-transmission electron microscope (HR-TEM) was employed to ensure the development of a nano-structured nature of the Al 6063 matrix. In the present work alloyed powder was milled for 20 h and 40 h at 300 rpm;and 20 h at 700 rpm in a hardened stainless steel medium. Using Williamson-Hall equation;crystallite size, lattice strain and lattice parameter of Al 6063 nanostructure alloy powder was estimated with broadening of XRD peaks. XRD results showed that the crystallite size of Al 6063 alloy powder reached 32 and 53 nm after 20 h at 700 rpm and 40 h at 300 rpm respectively.

Dielectric and Magnetic Properties of Nano-Structure BiFeO<SUB>3</SUB>Doped with Different Concentrations of Co Ions Prepared by Sol-Gel Method

BiFe1-xCoxO3 (x = 0, 0.03, 0.05 and 0.1) symbolic as (BFO, BF3CO, BF5CO and BF10CO) in powder form has been prepared by sol-gel technique using ethylenediamine tetraacetic acid (EDTA) as a chelating agent. X-ray diffraction (XRD) and FTIR analysis showed rhombohedra distorted BiFeO3 structure with compressive lattice distortion induced by the Co substitution at Fe sites. The transmission electron microscope (TEM) shows irregular particles. The additive of cobalt oxide has led to grains refining giving the following crystallite sizes of 18 nm for BF5Co. The scanning electron microscope (SEM) study reveals that the samples morphology shows relatively uniform grain size distribution. The dielectric properties of BiFeO3 nano-particles in the frequency range of 1 up to 5 MHz at RT revealed that the A.C. conductivity of the prepared samples reaches its maximum value in BF5CO. By decreasing BiFeO3 particle size as a result of doping with different Co ion concentrations, an enhancement in magnetization and a simultaneous suppression in current leakage occurred. The remnant magnetization Mr of BiFe1-xCoxO3 (x = 0, 0.03, 0.05, 0.1) ceramics significantly enhanced, which provides potential applications in information storage.

Preparation of nano-structured pure rare-earth bulks by combining inert-gas condensation with SPS

A number of techniques have been developed to synthesize nanocrystalline bulk materials,including inert-gas condensation and consolidation,electrodeposition,severe plastic deformation,crystallization of amorphous solid,surface mechanical attrition,and powder metallurgy.However,it is hard to produce the bulk with controllable nanostructures,especially with the grain sizes controllable in a wide range below 100 nm.In the conventional powder metallurgy,due to the fact that rapid coarsening of the particles ...

Er³⁺and Er³⁺/Yb³⁺Ions Embedded in Nano-Structure BaTi_0.9Sn_0.1O₃: Structure, Morphology and Dielectric Properties

Barium titanate tin oxides BaTi0.9Sn0.1O3 referred to as (BTSO) doped with 0.5Er3+ and co-doped with (0.75 and 1) Yb3+ ions, were prepared using a modified sol-gel method and calcinated at 1050?C in the air for 4 h. The influence of the selected rare earth element on the structure morphology, dielectric properties behavior was investigated. From TEM micrographs, it has appeared that the particles have a spherical shape with a small size in nanoscale. The average particle size is determined both by TEM and XRD diffraction was found to be in agreement and within the range between 45.9 and 57.7 nm. The effects of Lanthanide incorporation on the evolution of these nano-crystalline structures were followed by XRD and (FTIR). The XRD patterns give rise to a single perovskite phase, while the tetragonality was found to decrease gradually with Er3+ and Er3+/Yb3+ ions, respectively. FTIR results showed enhancement of the crystallinity and the absence of carbonates upon increasing Yb3+ ions concentration from 0.75 up to 1 mol%. The dielectric and conductivity properties were found to be enhanced by the nature and the concentration of the lanthanide element (Er3+, Yb3+) in the BTSO host lattice. The Curie temperature (Tc) shifted to a lower value from 117 for BTSO: 0.5Er to 93 for BTSO: 0.5Er/1Yb and the permittivity ε’ increased from 3972 to 6071, so BTSO: 0.5Er/1Yb good crystalline material candidate for capacitors application due to its higher permittivity.

Pushing the frontiers: Chip-based detection based on micro-and nano-structures

Changes in trace substances in human metabolites, which are related to disease processes and health status, can serve as chemical markers for disease diagnosis and symptom monitoring. Real-time online detection is an inevitable trend for the future of health monitoring, and the construction of chips for detection faces major challenges. The response of sensors often fails to meet the requirements for chipbased detection of trace substances due to the low efficiency of interfacial heterogeneous reactions, necessitating a rational design approach for micro-and nano-structures to improve sensor performance with respect to sensitivity and detection limits. This review focuses on the influence of micro-and nanostructures that used in chip on sensing. Firstly, this review categorizes sensors into chemiresistors, electrochemical sensors, fluorescence sensors, and surface enhanced Raman scattering(SERS) sensors based on their sensing principle, which have significant applications in disease diagnosis. Subsequently, commencing from the application requirements in the field of sensing, this review focuses on the different structures of nanoparticle(NP) assemblies, including wire, layered, core-shell, hollow, concave and deformable structures. These structures change in the size, shape, and morphology of conventional structures to achieve characteristics such as ordered alignment, high specific surface area, space limitation,vertical diffusion, and swaying behavior with fluid, thereby addressing issues such as poor signal transmission efficiency, inadequate adsorption and capture capacity, and slow mass transfer speed during sensing. Finally, the design direction of micro-and nano-structures, and possible obstacles and solutions to promote chip-based detection have been discussed. It is hope that this article will inspire the exploration of interface micro-and nano-structures modulated sensing methods.

Autophagy mediates osteoporotic bone regeneration induced by micro-/nano-structured modification on hydroxyapatite bioceramics

Osteoporosis(OP)is an age-related disease of bone metabolism,characterized by bone mass loss and bone mi-croarchitecture deterioration,the poor osteogenesis microenvironment of OP caused hardly repairing of the bone defects.As a dynamic process to fuel cellular renovation,autophagy has been proved to play a vital role in regulating cell differentiation and maintaining bone homeostasis.Traditional bone repairing biomaterials are hardly repairing the bone defects under OP pathological microenvironment.Therefore,it is essential to develop-ment novel biomaterials to improve osteoporotic osteogenesis.Compared to biochemical cues,biophysical cues exhibited more advantages in biocompatible and side effects.Herein,inspired by the importance of enhanced au-tophagic response in osteoporotic environment,we intend to utilize the micro-/nano-structured hydroxyapatite(mnHA)bioceramics as the mimic structure of natural bone tissue to regulate autophagic activity in ovariectomy bone mesenchymal stem cells(OVX-BMSCs),finally promote to bone regeneration in OP condition.The results indicated that mnHA bioceramics promoted cell adhesion and osteogenesis of OVX-BMSCs,and enhanced au-tophagy level in OVX-BMSCs.In the calvarial defects of OVX-rats,the mnHA scaffold acquired excellent bone repair effect.According to the current findings,regulating the level of autophagy could be a promising strategy for improve osteoporotic osteogenesis in the future.

Micro/nano-structured TiO2 surface with dual-functional antibacterial effects for biomedical applications

Implant-associated infections are generally difficult to cure owing to the bacterial antibiotic resistance which is attributed to the widespread usage of antibiotics.Given the global threat and increasing influence of antibiotic resistance,there is an urgent demand to explore novel antibacterial strategies other than using antibiotics.Recently,using a certain surface topography to provide a more persistent antibacterial solution attracts more and more attention.However,the clinical application of biomimetic nano-pillar array is not satisfactory,mainly because its antibacterial ability against Gram-positive strain is not good enough.Thus,the pillar array should be equipped with other antibacterial agents to fulfill the bacteriostatic and bactericidal requirements of clinical application.Here,we designed a novel model substrate which was a combination of periodic micro/nano-pillar array and TiO2 for basically understanding the topographical bacteriostatic effects of periodic micro/nano-pillar array and the photocatalytic bactericidal activity of TiO2.Such innovation may potentially exert the synergistic effects by integrating the persistent topographical antibacterial activity and the non-invasive X-ray induced photocatalytic antibacterial property of TiO2 to combat against antibiotic-resistant implant-associated infections.First,to separately verify the topographical antibacterial activity of TiO2 periodic micro/nano-pillar array,we systematically investigated its effects on bacterial adhesion,growth,proliferation,and viability in the dark without involving the photocatalysis of TiO2.The pillar array with sub-micron motif size can significantly inhibit the adhesion,growth,and proliferation of Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli).Such antibacterial ability is mainly attributed to a spatial confinement size-effect and limited contact area availability generated by the special topography of pillar array.Moreover,the pillar array is not lethal to S.aureus and E.coli in 24 h.Then,the X-ray induced photocatalytic antibacterial property of TiO2 periodic micro/nano-pillar array in vitro and in vivo will be systematically studied in a future work.This study could shed light on the direction of surface topography design for future medical implants to combat against antibiotic-resistant implant-associated infections without using antibiotics.