Journal of Nano Research Vol. 27

Abstract: This work presents a cost-effective and simple possibility to outperform the potential of a standard single side mask aligner. The limited functionality is extended to the capability of back side alignment with minimal effort without additional knowledge and integration of new process technologies. The whole presented process flow performs without the necessity of additional equipment as infrared back side wafer alignment kits or additional etching processes or clamps and brackets. The result is a front to back side alignment process with satisfactory deviation.

Abstract: The existence of the fourth fundamental circuit element, the memristor, was first postulated over 30 years ago by Leon Chua. The implementation of the first modern memristor prototype by Hewlett Packard Laboratories in 2008 initiated a great scientific interest for these unique nanoelectronic devices and currently, there is a growing variety of systems that exhibit memristive behavior. However, most of the research has focused on the properties of the single devices, therefore very little is known about their response when these devices are organized into networks. In this work, the composite characteristics of memristive elements connected in network configurations are studied and the relationships among the single devices are investigated. We finally show how the threshold-dependent nonlinear memristive behavior could be elaborated to make possible the development of novel and sophisticated digital/analog memristive nanosystems.

Abstract: A study of the structural and mechanical properties of nanocrystalline TiAlSiN gradient coatings deposited by cathodic arc deposition techniques at 500 °C and post-annealed at 525 °C is presented. Analysis of the coatings, chemical composition and microstructure revealed that the coatings have a structure based on (Ti, Al)N nanocrystals with an average size of 10 nm embedded in an amorphous Si₃N₄ phase. The study of the mechanical properties showed that post-annealing causes improvement and increase of the coatings hardness. A maximum hardness of 48 GPa and elastic modulus of 560 GPa were measured. Also, excellent adhesion to the WC-Co substrate was observed in the post-annealed coatings.

Abstract: Highly epitaxial LaBaCo₂O_5+δ thin films are successfully fabricated and annealed in different ambient conditions. The LaBaCo₂O_5+δ thin films under O₂ and N₂ annealing atmosphere are c-axis oriented with the interface relationship of [100]_LBCO//[10_LAO and (001)_LBCO//(001)_LAO. Annealing the film in N₂ ambient significantly increases the resistivity and magnetoresistance comparing to the films annealed in O₂ ambient. The magnetoresistance after annealing in N₂ is almost more than twice of the magnetoresistance after annealing in O₂. The result revealed that the electrical properties of the film are highly influenced by annealing atmosphere, indicating that the physical properties can be controlled by adjusting the post annealing atmosphere.

Abstract: Surface properties of nanostructures on 7 polyolephine foils were characterized using different analytical methods to discuss an effect of halogen presence in polymer chain to surface properties. Both sides of these foils were examined and compared. Surface roughness and morphology were determined by atomic force microscopy, contact angle by goniometry, surface polarity by electrokinetic analysis. X-ray photoelectron and ultraviolet visible spectroscopies were used for determination of surface chemistry. Combination of different analyses gives complex information about surface properties of the foils, which may be of importance for any future experiments, as well as for their application e.g. in tissue engineering and electronics.

Abstract: Though there are a numerous methods for chemical synthesis, biogenic synthesis of nanoparticles offers an attractive alternative to chemical synthesis methods. Therefore scientists are continuously engaged in searching hazard free, environment friendly methods of synthesis of nanoparticles with tailor-made structural properties using benign starting materials. Recently several groups have achieved success in the synthesis of Ag, Au, Pd nanoparticles with specific shape and size using extracts obtained from micro-organisms as well as various plant extracts. It will be a highly interesting problem to modify the procedure to develop green-chemical means of synthesizing “tailor-made” monodisperse nanoparticles of single polygonal particle morphology, exclusively. The main objective of this brief article is to give an idea about the most reliable, cost-effective and environment friendly synthetic protocols for metal nanoparticles of different size, shape, composition, and with a high degree of monodispersity.

Abstract: Colloidal Silver nanoparticles with a size of 5 nm produced by chemical reduction using poly ethylene glycol (PEG 200). Layers of silver nanoparticles and chitosan were deposited onto low density polyethylene (LDPE) substrate by layer by layer (LBL) self-assembly technique. Silver nanocomposite films were built by sequential dipping of LDPE film in either anionic silver nanoparticles or cationic chitosan. Silver nanoparticles and chitosan led to the formation of nanocomposite films possessing antimicrobial properties with the thickness of 2, 4, 8, 12 and 20 layers. Silver nanocomposite films were characterized by atomic force microscopy (AFM). Thermal, mechanical and barrier properties of LBL deposited nanocomposite films were investigated. Results showed that the LBL deposition of silver nanoparticles and chitosan increased the crystallinity of the composites and also improved mechanical and barrier properties of LDPE film significantly (p<0.05). Antimicrobial activity of silver nanocomposites against Escherichia coli and Staphylococcus aureus was evaluated. Growth kinetic parameters of E.coli and S.aureus affected by silver nanocomposites were calculated by modeling of absorbance data according to Gomperz equation. LDPE-silver nanocomposite affected bacterial growth parameters significantly (p<0.05). The specific growth rate reduced from 0.30 to 0.11 h^-1 for E. coli and decreased 0.27 to 0.06 h^-1 for S. aureus.

Abstract: We have studied the effects of vacancies on the structural, electronic and magnetic properties of zigzag-edged graphene nanoribbons (ZGNRs). Our calculations were carried out using an ab initio density functional pseudopotential computational method combined with the generalized gradient approximation for the exchange-correlation functional. The equilibrium geometries, electronic charge spin density distributions, electronic band structures, and magnetic moments were examined in the presence of single vacancy and double vacancies. Structural optimization showed that vacancies induce substantial structural changes in ZGNRs. We found that introducing vacancies into ZGNR changes the spatial distribution of neighbor atoms, particularly those located around the vacancies. Our calculations showed that the vacancies have significant effect on the magnetization of ZGNR. The calculations showed that the changes in the structural geometry, the electronic structure and the magnetization of ZGNR depend on the location of the vacancies with respect to the ribbon edges. These results suggest that vacancy defects can be used to modify the electronic and the magnetic properties of ZGNR.

Abstract: Silk nanoparticles were easily obtained from regenerated Antheraea Pernyi Silk Fibroin (ASF). The morphology and average size of the silk particles was sensitive to pH value of fibroin solution. The diameter of nanoparticles prepared was in the range of 30 nm to 1000 nm with a narrow size distribution. On this process, the molecular conformation of regenerated ASF changed from α-helix to β-sheet structure. The shape of prepared nanoparticles were regular spherical structure when the pH value was about 4.3 (pI) in ASF solution. Doxorubicin hydrochloride (DOX) was loaded in the ASF particles as drug release model and the drug-loading ratio was 3.4 %. The release rate of DOX from ASF nanoparticles was pH sensitive. After 23 days release, there was still 84% DOX in the ASF nanoparticles. The result suggested that the ASF nanoparticles might be suitable microcarriers for drug delivery.

Abstract: A novel composite of poly (ethylene glycol) (PEG) functionalized gold nanoparticles (AuNP-PEG) dispersed within Poly (lactic-go-glycolic) (PLGA) films, were prepared to demonstrate the concept of a combined targeted and sustained implant material. This technology offers the promise of improved therapies for difficult to treat tumors such as Gliomas. Gold nanoparticles (AuNPs) synthesized via a modified Turkevich method, were functionalized with thiol terminated polyethylene glycol (PEG), washed using centrifugation, dried, re-suspended in a solution of PLGA in dichloromethane and finally vacuum dried to produce the solvent cast films. The degradation and nanoparticle release profile of these films were studied by immersion in PBS media at 37 °C over periods of up-to 58 days. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was conducted. The release of the AuNPs-PEG nanoparticles during degradation was studied using inductively coupled plasma mass spectroscopy (ICP-MS). It was observed that the AuNP-PEG nanoparticles were individually dispersed within the PLGA and that their addition extended the degradation time of the PLGA film, but did not appear to alter the nature of degradation. The nanoparticle release from the composite films displayed an approximately zero-order release profile.