scholarly journals Template-controlled mineralization: Determining film granularity and structure by surface functionality patterns

2015 ◽  
Vol 6 ◽  
pp. 1763-1768 ◽  
Author(s):  
Nina J Blumenstein ◽  
Jonathan Berson ◽  
Stefan Walheim ◽  
Petia Atanasova ◽  
Johannes Baier ◽  
...  

We present a promising first example towards controlling the properties of a self-assembling mineral film by means of the functionality and polarity of a substrate template. In the presented case, a zinc oxide film is deposited by chemical bath deposition on a nearly topography-free template structure composed of a pattern of two self-assembled monolayers with different chemical functionality. We demonstrate the template-modulated morphological properties of the growing film, as the surface functionality dictates the granularity of the growing film. This, in turn, is a key property influencing other film properties such as conductivity, piezoelectric activity and the mechanical properties. A very pronounced contrast is observed between areas with an underlying fluorinated, low energy template surface, showing a much more (almost two orders of magnitude) coarse-grained film with a typical agglomerate size of around 75 nm. In contrast, amino-functionalized surface areas induce the growth of a very smooth, fine-grained surface with a roughness of around 1 nm. The observed influence of the template on the resulting clear contrast in morphology of the growing film could be explained by a contrast in surface adhesion energies and surface diffusion rates of the nanoparticles, which nucleate in solution and subsequently deposit on the functionalized substrate.

1997 ◽  
Vol 3 (S2) ◽  
pp. 431-432
Author(s):  
S. A. Harfenist ◽  
Z. L. Wang ◽  
R. L. Whetten ◽  
I. Vezmar ◽  
M. M. Alvarez ◽  
...  

Silver nanocrystals passivated by dodecanethiol self-assembled monolayers were produced using an aerosol technique described in detail elsewhere [1]. Self-assembling passivated nanocrystal-superlattices (NCS's) involve self-organization into monolayers, thin films, and superlattices of size-selected nanoclusters encapsulated in a protective compact coating [2,3,4,5,6,7]. We report the preparation and structure characterization of three-dimensional (3-D) hexagonal close-packed Ag nanocrystal supercrystals from Ag nanocrystals of ˜4.5 nm in diameters. The crystallography of the superlattice and atomic core lattices were determined using transmission electron microscopy (TEM) and high-resolution TEM.SEM was used to image the nanocrystal superlattices formed on an amorphous carbon film of an TEM specimen grid (fig. la). The superlattice films show well shaped, sharply faceted, triangular shaped sheets. Figure lb depicts numerous Ag nanocrystal aggregates uniformly distributed over the imaging region. Inset in this figure is an enlargement of the boxed region at the edge of a supercrystal typifying the ordered nanocrystal packing.


2006 ◽  
Vol 71 (9) ◽  
pp. 1383-1391 ◽  
Author(s):  
Maryte Kažemekaite ◽  
Vilma Railaite ◽  
Arunas Bulovas ◽  
Zita Talaikyte ◽  
Gediminas Niaura ◽  
...  

The newly synthesized 1,4-naphthoquinones linked via nitrogen atom to a short chain with terminal sulfanyl group form self-assembled monolayers on gold. The main electrochemical parameters of the monolayers were determined by cyclic voltammetry. Combined voltammetric and in situ Fourier-transform surface-enhanced Raman spectroscopic studies of the Au electrode modified with the title compounds clearly evidence that naphthoquinone group transforms into naphthalenediol during a reduction process.


2020 ◽  
Vol 18 (9) ◽  
pp. 669-685
Author(s):  
Padmaker Pandey ◽  
Anamika Pandey ◽  
Shruti Singh ◽  
Nikhil Kant Shukla

A compromising and well-organized model system is needed for investigating the molecular behaviour of biomolecules as many transduction processes and biological recognition occur at biological surfaces. The application of techniques in interfacial surfaces like one molecule thick films has made a feasible and significant tool for modern scientific studies. Self Assembling Monolayers (SAMs) technology is a very useful means for producing monomolecular films of various biological molecules on different substrates. Carbon Nanotubes (CNTs) have length-to-diameter aspect ratio property which provides a large surface-to-volume ratio, making it an intensely capable material for biomolecular attachments. The incorporation of Carbon Nanotubes (CNTs) with biological systems forming functional assemblies has shown an explored area of research. Organo-sulfur mainly alkanethiol (CnH2n+1–SH) molecules get adsorbed onto CNTs. This phenomenon has grabbed a lot of attention because Self Assembling Monolayers (SAMs) of organo-sulfur compound acts as an example system for understanding important chemical, physical or biological processes.


Author(s):  
Joel Sachs ◽  
Jocelyn Pender ◽  
Beatriz Lujan-Toro ◽  
James Macklin ◽  
Peter Haase ◽  
...  

We are using Wikidata and Metaphactory to build an Integrated Flora of Canada (IFC). IFC will be integrated in two senses: First, it will draw on multiple existing flora (e.g. Flora of North America, Flora of Manitoba, etc.) for content. Second, it will be a portal to related resources such as annotations, specimens, literature, and sequence data. Background We had success using Semantic Media Wiki (SMW) as the platform for an on-line representation of the Flora of North America (FNA). We used Charaparser (Cui 2012) to extract plant structures (e.g. “stem”), characters (e.g. “external texture”), and character values (e.g. “glabrous”) from the semi-structured FNA treatments. We then loaded this data into SMW, which allows us to query for taxa based on their character traits, and enables a broad range of exploratory analysis, both for purposes of hypothesis generation, and also to provide support for or against specific scientific hypotheses. Migrating to Wikidata/Wikibase We decided to explore a migration from SMW to Wikibase for three main reasons: simplified workflow; triple level provenance; and sustainability. Simplified workflow: Our workflow for our FNA-based portal includes Natural Language Processing (NLP) of coarse-grained XML to get the fine-grained XML, transforming this XML for input into SMW, and a custom SMW skin for displaying the data. We consider the coarse-grained XML to be canonical. When it changes (because we find an error, or we improve our NLP), we have to re-run the transformation, and re-load the data, which is time-consuming. Ideally, our presentation would be based on API calls to the data itself, eliminating the need to transform and re-load after every change. Provenance: Wikidata's provenance model supports having multiple, conflicting assertions for the same character trait, which is something that inevitably happens when floristic data is integrated. Sustainability: Wikidata has strong support from the Wikimedia Foundation, while SMW is increasingly seen as a legacy system. Wikibase vs. Wikidata Wikidata, however, is not a suitable home for the Integrated Flora of Canada. It is built upon a relatively small number of community curated properties, while we have ~4500 properties for the Asteraceae family alone. The model we want to pursue is to use Wikidata for a small group of core properties (e.g. accepted name, parent taxon, etc.), and to use our own instance of Wikibase for the much larger number of specialized morphological properties (e.g. adaxial leaf colour, leaf external texture, etc.) Essentially, we will be running our own Wikidata, over which we would exercise full control. Miller (2018) decribes deploying this curation model in another domain. Metaphactory Metaphactory is a suite of middleware and front-end interfaces for authoring, managing, and querying knowledge graphs, including mechanisms for faceted search and geospatial visualizations. It is also the software (together with Blazegraph) behind the Wikidata Query Service. Metaphactory provides us with a SPARQL endpoint; a templating mechanism that allows each taxonomic treatment to be rendered via a collection of SPARQL queries; reasoning capabilities (via an underlying graph database) that permit the organization of over 42,000 morphological properties; and a variety of search and discovery tools. There are a number of ways in which Wikidata and Metaphactory can work together, and we are still exploring questions such as: Will provenance be managed via named graphs, or via the Wikidata snak model?; How will data flow between the two platforms? Etc. We will report on our findings to date, and invite collaboration with related Wikimedia-based projects.


2006 ◽  
Vol 4 (14) ◽  
pp. 473-477 ◽  
Author(s):  
J Bowen ◽  
M.E Pettitt ◽  
K Kendall ◽  
G.J Leggett ◽  
J.A Preece ◽  
...  

The settlement and adhesion of Navicula perminuta and Ulva linza to methyl-terminated alkanethiol self-assembled monolayers (SAMs) of increasing chain length has been investigated. Organisms were allowed to settle onto the monolayers and were subsequently exposed to hydrodynamic shear stress in order to determine their adhesion strength. Results show that as the SAM structure changes from amorphous to crystalline (C14), there is a marked change in the adhesion of N. perminuta and U. linza . Given that the SAMs in the series all exhibit similar contact angle behaviour and surface energy, it is hypothesized that the lubricity of the surface plays a role in determining the surface adhesion.


Surfaces ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 29-42
Author(s):  
Emanuele Salvietti ◽  
Walter Giurlani ◽  
Maria Foresti ◽  
Maurizio Passaponti ◽  
Lorenzo Fabbri ◽  
...  

The passivation of metal electrodes covered by self-assembled monolayers of long-chain thiols is well known. The disappearance of the voltammetric peak of redox species in solution is a classical test for the formation of full layers of thiols. Similar studies on semiconductors are still very limited. We used silver surfaces covered by an ultrathin layer of CdS as substrate for self-assembling of n-hexadecanethiol (C16SH), and we compared the experimental results with those obtained by using the bare silver surface as substrate. The strong insulating effect of C16SH deposited on Ag(III) is shown by the inhibition of the voltammetric peak of Ru(NH3)63+/2+. On the contrary, the voltammogram obtained on CdS-covered Ag(III) is very similar to that obtained on the bare Ag(III) electrode, thus suggesting that the presence of CdS exerts a contrasting effect on the passivation of the silver electrode. A crucial point of our work is to demonstrate the effective formation of C16SH monolayers on Ag(III) covered by CdS. The formation of full layers of C16SH was strongly suggested by the inhibition of the stripping peak of Cd from the CdS deposit covered by C16SH. The presence of C16SH was confirmed by electrochemical quartz crystal microbalance (EQCM) measurements as well as by Auger electron spectroscopy (AES) analysis.


2013 ◽  
Vol 20 (03n04) ◽  
pp. 1350028
Author(s):  
XIULAN ZHANG ◽  
HENG ZHANG ◽  
YIHONG YANG ◽  
ZHENYU CHEN

The self-assembling behavior and inhibition effect of dodecanethiol self-assembled monolayers (SAMs) on copper surface were investigated by atomic force microscopy (AFM) and electrochemical methods. The assembling process was monitored by AFM phase images. The assembling time influences the corrosion protection efficiency of dodecanethiol SAMs. Surface friction significantly decreases when the copper surface is covered by SAMs.


Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.


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