Development of nanostructured Al/SiO2 composite film for vibroisolation applications

This paper presents the investigation of surface morphology, wetting and chemical properties of the nanocomposite Al/SiO2 film, which can be used as a shock generated vibration isolator for microelectromechanical devices. AFM analysis shows that two-step prepared Al/SiO2 composite film has regular nanoisland type surface topography provided by SiO2 nanospheres. EDS analysis confirms that SiO2 nanospheres are well distributed on the substrate. Carbon found in the composition of composite film can be attributed to the residuals of organic compounds used for the preparation of SiO2 nanospheres. FTIR analysis confirms formation of the Si-O and Si-OH functional groups and the presence of –CH3 stretching group can be related to the improved non-wetting behavior of the composite

Analysis of the current logistics and transport challenges in the context of the changing environment

The rapidly changing world determines changes in the business processes. Logistics and transport are the areas facing constant changes. Therefore, an important point is to analyse the current problems of logistics and transport within the context of the changing environment. For many years, the experts of the Dept of Logistics and Transport Management of the Faculty of Transport Engineering from Vilnius Gediminas Technical University have been pursuing research both, in the Baltic Sea Region (BSR) in Lithuania and foreign countries. This research has been directed toward improvements to logistics and the entire supply chain in pursuit of economic, social and ecological competitiveness, an increase in the competitiveness and attractiveness of the transport system in the context of sustainable development, the impact of this system on the economic and social welfare of society, an increase in the competitiveness and attractiveness of the transport sector of improving the legal framework and the application of innovative technologies (including IT) in the transport sector aimed at implementing economic and social cohesion goals. The article deals with some of the key issues of the above introduced research

Silikatinio „float“ stiklo paviršiaus paruošimo adhezinei jungčiai pagerinti metodai

Šiame darbe buvo tiriamos įvairiais metodais paruošto silikatinio „float“ stiklo paviršiaus drėkstamumas. Silikatinio „float“ stiklo paviršiaus drėkinimo kampas nustatytas aktyvių kontūrų paviršiaus drėkinimo kampo nustatymo metodu. Ant įvairiais metodais paruošto stiklinio pagrindo paviršiaus buvo užgarinama plona chromo danga. Brėžimo testu buvo įvertinta plonos chromo dangos adhezija su stikliniu pagrindu. Atlikta lyginamoji adhezijos analizė. Taip pat buvo tirta stiklinio pagrindo pakaitinimo (100°C) prieš chromo vakuuminį garinimą įtaka chromo dangos adhezijai su stikliniu pagrindu. Buvo nustatyta, kad silikatinio „float“ stiklo paviršius geriausiai paruošiamas (drėkinimo kampas siekė nuo 4° iki 8°) naudojant deguonies plazmą ir RCA-1 paviršiaus paruošimo metodus. Lyginant silikatinio „float“ stiklo viršutinę (atmosferinę pusę) ir apatinę (tą pusę, kuri kontaktavo su skystu alavu) puses, nustatyta, kad po daugumos paviršiaus paruošimo metodų apatinės pusės paviršiaus drėkinimo kampas tampa didesnis. Ar⁺ jonų pluoštelio poveikis sulygina abiejų stiklo pusių paviršiaus drėkstamumą. Stiklinio pagrindo adhezija su plona chromo danga buvo didžiausia, paruošus stiklinį pagrindą deguonies jonų plazma ir RCA-1 paviršiaus paruošimo metodais (kritinė apkrova paruošus deguonies jonų plazma, 0,169 N; RCA-1 0,14 N). Plonos chromo dangos adhezija su stikliniu pagrindu padidėja, pakaitinus stiklinį pagrindą prieš chromo vakuuminį garinimą.<p>DOI: <a href="http://dx.doi.org/10.5755/j01.ms.18.2.1924">http://dx.doi.org/10.5755/j01.ms.18.2.1924</a></p

Ruoškimės artojų varžyboms

Vytauto Didžiojo universitetasŽemės ūkio akademij

Recovery Behavior of Microstructured Thiol-Ene Shape-Memory Film

In this work, surface microstructurization was coupled with shape-memory polymer to generate reversibly tunable surface properties. A photopolymerizable thiol-ene composition comprising a mixture of pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TTT) and 2,2-dimethoxy-2-phenylacetophenone (DMPA) was used to prepare microstructured thiol-ene shape-memory film via casting and UV polymerization on the electron beam lithography fabricated arrays of 1 &#181;m and 2 &#181;m square pits. The mechanical deformation via compression and recovery of the surface microstructure were investigated. Results show that, after heat treatment of the deformed thiol-ene film, the recovery yields for microstructures were not worse than 90% &#177; 2% and 93% &#177; 2% for structures imprinted with 1 &#181;m and 2 &#181;m square pit micro imprint stamps. Additionally, heat treatment of deformed thiol-ene film resulted in the recovery of intense diffraction colors and laser diffraction patterns. This study opens up an avenue of incorporating microstructured shape-memory films for new products, e.g., optical security devices, superhydrophobic coatings, medical diagnostics and biosensors

Control of Polydimethylsiloxane Surface Hydrophobicity by Plasma Polymerized Hexamethyldisilazane Deposition

The properties of a polydimethylsiloxane (PDMS) surface were modified by a one-step deposition of plasma polymerized hexamethyldisilazane (pp-HMDS) by the arc discharge method. Scanning electron microscopy, atomic force microscopy, and Fourier-transform infrared spectroscopy analytical techniques were employed for morphological, structural, and chemical characterization of the pp-HMDS modified PDMS surface. The changes in PDMS substrate wetting properties were evaluated by means of contact angle measurements. The unmodified PDMS surface is hydrophobic with a contact angle of 122&deg;, while, after pp-HMDS film deposition, a dual-scale roughness PDMS surface with contact angle values as high as 170&deg; was obtained. It was found that the value of the contact angle depends on the plasma processing time. Chemically, the pp-HMDS presents methyl moieties, rendering it hydrophobic and making it an attractive material for creating a superhydrophobic surface, and eliminating the need for complex chemical routes. The presented approach may open up new avenues in design and fabrication of superhydrophobic and flexible organosilicon materials with a self-cleaning function

Preface

Vytauto Didžiojo universitetasŽemės ūkio akademij

Structural and Chemical Peculiarities of Nitrogen-Doped Graphene Grown Using Direct Microwave Plasma-Enhanced Chemical Vapor Deposition

Chemical vapor deposition (CVD) is an attractive technique which allows graphene with simultaneous heteroatom doping to be synthesized. In most cases, graphene is grown on a catalyst, followed by the subsequent transfer process. The latter is responsible for the degradation of the carrier mobility and conductivity of graphene due to the presence of the absorbants and transfer-related defects. Here, we report the catalyst-less and transfer-less synthesis of graphene with simultaneous nitrogen doping in a single step at a reduced temperature (700 &deg;C) via the use of direct microwave plasma-enhanced CVD. By varying nitrogen flow rate, we explored the resultant structural and chemical properties of nitrogen-doped graphene. Atomic force microscopy revealed a more distorted growth process of graphene structure with the introduction of nitrogen gas&mdash;the root mean square roughness increased from 0.49 &plusmn; 0.2 nm to 2.32 &plusmn; 0.2 nm. Raman spectroscopy indicated that nitrogen-doped, multilayer graphene structures were produced using this method. X-ray photoelectron spectroscopy showed the incorporation of pure pyridinic N dopants into the graphene structure with a nitrogen concentration up to 2.08 at.%