Chemically patterned flat stamps provide an effective solution to avoid mechanical stamp-stability problems currently encountered in microcontact printing. A new method is developed to fabricate chemical patterns on a flat PDMS stamp using nanoimprint lithography. Sub-100 nm gold patterns are successfully replicated by these chemically patterned flat PDMS stamps.
Abstract A novel nanopatterning process was developed by combining capillary force lithography (CFL) and microcontact printing (µCP). Flat polydimethylsiloxane (PDMS) was used as the substrate in CFL, and after chemical functionalization, as the stamp in µCP, which increased the resolution of both methods. The polymer patterns, produced by CFL on a thin polymer film on the flat PDMS substrate, acted as a mask to oxidize the uncovered regions of the PDMS. The chemical patterns were subsequently formed by gas phase evaporation of a fluorinated silane. After removal of the polymer, these stamps were used to transfer thiol inks to a gold substrate by µCP. Gold patterns at a scale of less than 100 nm were successfully replicated by these chemically patterned flat PDMS stamps.
Different methods to create chemically patterned, flat PDMS stamps with two different chemical functionalities were compared. The best method for making such stamps, functionalized with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (PFDTS) and 3-(aminopropyl)triethoxysilane (APTS), appeared to be full functionalization of a freshly oxidized flat PDMS stamp with either adsorbate, followed by renewed oxidation through a mask and attachment of the other adsorbate. These stamps were used to transfer polar inks (a thioether-functionalized dendrimer and a fluorescent dye) by microcontact printing. The PFDTS monolayer was used as a barrier against ink transfer, while the APTS SAM areas functioned as an ink reservoir for polar inks. The printing results confirmed the excellent transfer of hydrophilic inks with these stamps to gold and glass substrates, even from aqueous solutions. Attachment of a fluorescent dye on the amino-functionalized regions shows the possibility of the further modification of the chemically patterned stamps for tailoring of the stamps' properties.
Various sulfur-modified alpha-cyclodextrin (alpha-CD) derivatives formed ordered monolayers on gold surfaces as confirmed by water contact angle goniometry, electrochemistry, X-ray photoelectron spectroscopy, and atomic force microscopy measurements. Self-assembled monolayers (SAMs) of the adsorbates showed high polarity, uniform monolayer arrangement, and low charge transfer resistance. Electrochemical capacitance measurements were used to determine the binding affinity of aliphatic carboxylic acid salts with four, six, and eight carbon atoms. The nonmethylated cyclodextrin host-guest pairs showed 1-2 orders of magnitude higher binding constants on surfaces than in solution.
This report focuses on the feasibility of the power-to-ammonia concept. Power-to-ammonia uses produced excess renewable electricity to electrolyze water, and then to react the obtained hydrogen with nitrogen, which is obtained through air separation, to produce ammonia. This process may be used as a “balancing load” to consume excess electricity on the grid and maintain grid stability. The product, ammonia, plays the role of a chemical storage option for excess renewable energy. This excess energy in the form of ammonia can be stored for long periods of time using mature technologies and an existing global infrastructure, and can further be used either as a fuel or a chemical commodity. Ammonia has a higher energy density than hydrogen; it is easier to store and transport than hydrogen, and it is much easier to liquefy than methane, and offers an energy chain with low carbon emissions. The objective of this study is to analyze technical, institutional and economic aspects of power-to-ammonia and the usage of ammonia as a flexible energy carrier.
Kimutattuk, hogy a nem-hatszoges (n-H) gyűrűket is tartalmazo szen nanoszerkezetek (Y-elagazas, hengerspiralok, stb.) novekedeset az n-H gyűrűk beepulesenek mikentje hatarozza meg, uj modellt javasoltunk hengerspiralok szerkezetere. Elsőkent keszitettunk Si3N4/szen nanocső kompozitokat es megmutattuk, hogy megfelelő szinterelesi parameterek alkalmazasaval megőrizhetők az elektromosan vezetőve tett matrix jo tulajdonsagai. Uj nanocső novesztesi modszereket dolgoztunk ki. Elsőkent bizonyitottuk, hogy az ionos besugarzas nyoman a szen nanocsoveken, valoban a szimulacioknak megfelelő topografiai alakzatok jelennek meg. Elmeleti modellt adtunk a hibak kornyezeteben azt STM felveteleken megfigyelhető szuperstrukturak eredetere. Megmutattuk, hogy a funkcionalizalas modjatol fuggően a funkcios csoportok szigetszerűen, vagy folytonoshelyezkednek el. A funkcios csoportok megvaltoztatjak a nanocsovek valaszjelet a kornyezetben jelenlevő gazokra/gőzokre. Sikeresen fejlesztettunk elmeleti modszereket a gyengen kolcsonhato nagy atomszamu rendszerek leirasara es elsőkkent vizsgaltuk sok szen nanocsoből felepulő kotegekben a csovek egymassal valo kolcsonhatasat. Első elvekre illetve sűrűsegfunkcional modszerre alapozva vizsgaltuk a duplafalu szen nanocsovek, illetve a nanocsőben elhelyezkedő szenlancok tulajdonsagait. A sajatfejlesztesű hullamcsomagdinamikai modszerunkkel elsőkkent vizsgaltuk az elektronhullamok terjedeset szen nanocső Y elagazasokban. | We showed that the growth of carbon nanostructures containing non-hexagonal (n-H) rings (Y-branches, coils etc.) is determined by the incorporation of the n-H rings, we proposed a new model for the structure of regularly coiled carbon nanotubes. We prepared the first Si3N4/carbon nanotube composites and we showed the under proper sintering conditions the composite can be made conductive while keeping the remarkable properties of the matrix. We developed new growth methods for carbon nanotubes. We showed for the first time that ion irradiation of carbon nanotubes indeed creates the features predicted by simulations. We proposed a theoretical description of the superstructures observed in STM in the vicinity of the defects. Depending on the way in which the functionalization is done, the functional groups appear on the nanotubes in an island-like or a continuous fashion. Their presence influences the response of the carbon nanotubes to the gases/vapors present in the atmosphere. We developed successfully theoretical tools for the description of weakly interacting large system and investigated for the first time the interaction of tubes in carbon nanotube bundles containing many tubes. Based on first principle and density functional calculations we investigated the double wall carbon nanotubes and linear carbon chains located inside a SWCNT. Using our own wave packet dynamical software we investigated the propagation of electronic waves in carbon nanotube Y junctions.
Within the Flexnode Plus project the long-term degradation characteristics of a proton exchange membrane (PEM) electrolyzer (5.5 kW, AC, 1 Nm3/h H2) and fuel cell (1.0 kW, DC, 0.9 Nm3/h) was experimentally tested. The electrolyzer unit was operated at various loads and pressures for approximately 750 hours in total, while the fuel cell was operated at a constant load of 1 Ω resistance for approximately 1120 hours in total. The efficiency of the hydrogen production in the electrolyzer and the electricity production in the fuel cell was expressed using the hourly average system efficiency and average cell efficiency. In order to predict the state of health and remaining lifetime of the electrolyzer cell and fuel cell, the decay of the cell voltage over time was monitored and the direct mapping from aging data method was used. The electrolyzer cell showed a stable cell voltage and cell efficiency in the studied time period, with an average cell voltage decay rate of 0.5 μV/h. The average cell voltage of the fuel cell dropped with a rate of 2 μV/h during the studied time period.
