Original Substrate Research Articles

Roughness-enhanced collection of condensed droplets.

Gravity shedding of droplets is limited by droplet pinning, a major limitation for low condensation processes and in particular passive dew harvesting in its use as an alternative source of water. We present experiments showing that, paradoxically, a simple surface treatment increasing roughness (sand-blasting) favors droplet shedding compared to the original substrate, provided that sand-blasting does not increase too much the surface roughness. Sand-blasting ensures the high density of nucleation sites and enhances drops coalescence and growth at a sub-micron scale, thus lowering the lag-time to obtain drop sliding during condensation. Early nucleation indeed overcompensates the delay increase due to roughness. Edges of the substrate, where drops grow faster, also improve water collection, thanks to the early sliding of edge drops that behave as natural wipers. Combining the effects of sand-blasting and edges increases significantly the rate of collection of dew condensation on a substrate at a given time, gains of about 30% can be commonly obtained.

Transfer printing of nanomaterials and microstructures using a wire bonder

Scalable and cost-efficient transfer of nanomaterials and microstructures from their original fabrication substrate to a new host substrate is a key challenge for realizing heterogeneously integrated functional systems, such as sensors, photonics, and electronics. Here we demonstrate a high-throughput and versatile integration method utilizing conventional wire bonding tools to transfer-print carbon nanotubes (CNTs) and silicon microstructures. Standard ball stitch wire bonding cycles were used as scalable and high-speed pick-and-place operations to realize the material transfer. Our experimental results demonstrated successful transfer printing of single-walled CNTs (100 m-diameter patches) from their growth substrate to polydimethylsiloxane, parylene, or Au/parylene electrode substrates, and realization of field emission cathodes made of CNTs on a silicon substrate. Field emission measurements manifested excellent emission performance of the CNT electrodes. Further, we demonstrated the utility of a high-speed wire bonder for transfer printing of silicon microstructures (60 m 60 m 20 m) from the original silicon on insulator substrate to a new host substrate. The achieved placement accuracy of the CNT patches and silicon microstructures on the target substrates were within 4 m. These results show the potential of using established and extremely cost-efficient semiconductor wire bonding infrastructure for transfer printing of nanomaterials and microstructures to realize integrated microsystems and flexible electronics.

The responses of human gingival fibroblasts to magnesium-doped titanium.

The titanium (Ti) implant is widely used in implant dentistry; yet peri-implantitis has always been one of the most common and serious complications. Here, we demonstrated that magnesium-doping would be an effective way of enhancing the integration between implant surfaces and gingival tissues, which is critical to peri-implant health. The magnesium (2.76-6.35 at %) was immobilized onto the titanium substrate by a magnesium plasma immersion ion implantation (Mg-PIII) technique. Mg-PIII treatments did not alter surface topographies of the original titanium substrate but improved its hydrophilicity. The in vitro study including cell viability, adhesion, proliferation, migration, and real-time polymerase chain reaction assays disclosed improved adhesion, proliferation, migration, and extracellular matrix remodeling abilities of human gingival fibroblasts (HGFs) on the magnesium-doped titanium. The results of western blot suggested that the Mg-modified titanium induced the phosphorylation of AKT through the activation of PI3K. Our results revealed that magnesium-doping would potentially enhance soft tissue sealings by promoting cellular functions of HGFs in a dose-dependent manner, boding well for its applications on surfaces of implant necks in early peri-implant soft tissue integrations.

Nanosecond pulsed fiber laser cleaning of natural marine micro-biofoulings from the surface of aluminum alloy

Abstract Herein, environmentally effective nanosecond (30 ns) pulsed fiber laser cleaning technology was innovatively used to remove natural marine micro-biofoulings with the thickness of 61.7 ± 26.5 μm from the surface of aluminum alloy. The morphologies and chemical compositions of the uncleaned and cleaned surfaces of the samples were examined and analyzed by field emission scanning electron microscopy (FESEM), electron microprobe (EPMA), atomic force microscopy (AFM), and energy dispersive spectroscopy (EDS). The wettability of cleaned surface was studied by contact angle analyser. Successful cleaning of the aluminum surfaces to remove marine micro-biofoulings can be achieved by using different laser fluences (1.38–5.52 J/cm2). The aluminum content of laser-cleaned surface was 88 wt% approximately, which reached up to 91.7% of that of the original substrate surface. Mechanism analysis indicated that laser-induced vaporization and ablation broke and eradicated of marine micro-biofoulings. The generated new surfaces were with free of damage and acceptable. At specific laser fluences (5.52 J/cm2), the surface even had additional superhydrophobicity which provides the feasibility of antifouling in the periodic service. This work offers fundamental research and practical guidance for laser cleaning of marine micro-biofoulings on the surface of aluminum alloy.

Stress corrosion cracking of simulated heat-affected zone in a CF8A weld in high temperature water

In this study, thermal simulation was performed to conduct thermal cycles on CF8A cast austenitic stainless steel substrates with different ferrite contents to simulate the microstructures that form near a weld fusion boundary. The effects of ferrite content and morphology on the mechanical properties of CF8A were investigated. The stress corrosion cracking (SCC) susceptibility of the specimens was evaluated with slow strain rate tensile (SSRT) tests in a simulated boiling water reactor (BWR) coolant environment.The results indicated that an increase in the ferrite content of the CF8A base metal led to a minor increase in hardness. Thermal simulation caused a marked increase in ferrite content, especially in the high ferrite CF8A substrate. The yield strengths of the tested samples increased obviously with increasing ferrite content, but the ductility decreased. The ultimate tensile strengths of the samples reached a plateau when the ferrite number (FN) was greater than 18. The applied thermal simulation greatly improved the impact toughness of high ferrite CF8A in comparison with the original substrate. The results indicated that the samples with high ferrite content had a shorter rupture life but greater fracture strength than those with low ferrite content strained in high temperature water. Moreover, cleavage-like fracture was found in all of the samples that suffered from SCC. The SCC cracks were observed to be more likely to propagate along the δ/γ interfaces of a CF8A. Furthermore, crack initiation and growth inside the γ of low ferrite CF8A contributed to a great loss in strength in a high temperature water environment.

P‐9.10: Fabrication of micro scale and ultra‐thin LEDs for micro‐LED display applications

Presented here are the fabrication techniques for preparing micro scale and ultra‐thin LEDs for micro‐LED display applications. Lateral dimension less than 100µm and thickness of 5µm LED devices are fabrication and the preparing micro LEDs are transferred from the original growth substrate to the glass substrate successfully. The optoelectronic performance of micro scale and ultra‐thin LEDs transferred on to the glass substrate as good as that of on the original growth substrate has achieved.

Erosion of cold sprayed aeronautical coatings

ABSTRACTAluminium-Silicon alloys, like Al C355, are extensively used in aeronautical applications, where light materials are required. Consequently, it is necessary to develop maintenance and overhaul technologies to extend the life of metallic components used in the aeronautical sector. Cold Spray (CS) represents a promising alternative to repair damaged light alloys surfaces. However, the repaired component should exhibit similar properties as the original substrate. In particular, degradation by erosion is usual during service in aeroplane operation. This is precisely the aim of this research: to evaluate the erosion performance of Al C355 coatings cold sprayed onto the same bulk alloy. Air jet-erosion tests were performed on the coatings and substrate, according to ASTM G76 standard. Coatings processed by CS using standard parameters exhibit lower erosion performance than the substrate. However, the erosion resistance of coatings deposited using improved conditions was similar to that observed in the uncoated substrate.

A comprehensive practical laboratory course on protein engineering: Evolution of a glycine oxidase variant active on the herbicide glyphosate.

Protein engineering represents a modern approach to generate novel proteins for the different fields of biotechnology. Here, we report about an 8-day laboratory activity in which students generate enzyme variants to degrade the herbicide glyphosate. The students conduct a true research experiment in an important field (bioremediation by novel, engineered enzymes) and are introduced to widely used techniques in molecular biology and protein biochemistry laboratories. Based on a docking analysis of glycine (the original substrate) and of glyphosate into the active site of glycine oxidase, residues putatively involved in substrate selectivity are identified that will become the target of site-saturation mutagenesis. Each group of students focuses on the library generated at one position and selects the most active variant based on colorimetric screening. Following protein overexpression in Escherichia coli, the selected glycine oxidase variants are purified and their kinetic properties on glycine and glyphosate assessed. The best variant identified by the whole class is then used for detecting the herbicide in water. With the help of the professor, students can improve technical skills, ability to evaluate results, team work activity, and critical thinking. © 2019 International Union of Biochemistry and Molecular Biology, 47(6):689-699, 2019.

Comparison of adsorption mechanisms for cadmium removal by modified zeolites and sands coated with Zn-layered double hydroxides

Layered double hydroxides (LDHs) have been applied as one of the most efficient adsorbents. As the most common natural filtering substrates, zeolites and sands were coated with Zn-layered double hydroxides (Zn-LDHs) and studied in this research. The scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) images confirmed LDHs coating on substrates. From isothermal adsorption tests, the modified substrates exhibited significant enhancements for the Cd(II) adsorption capacity than original substrates, especially for ZnFe-LDHs-modified sands whose maximum theoretical Cd(II) adsorption capacities (1103.70 mg·kg−1) were nearly three times as high as that of the originalsands (400.00 mg·kg−1). And the desorption efficiencies of original and modified substrates were over 67%. Additionally, the Cd(II) adsorption capacities were higher under the circumstance of co-existence ions including K+, NH4+, NO3−, HPO42−, while the appearance of Mg2+ would affect the Cd(II) adsorption negatively. The adsorption dynamic data were well described by pseudo-second-order model. Cd(II) adsorption by original and modified zeolites, original and modified sands were a spontaneous reaction. The Cd(II) adsorption process of LDHs-modified zeolites was a actually endothermic process, while for original zeolites, it was a exothermic process. The Cd(II) adsorption process of sands before and after modification was an endothermic process.

Fabrication of Silica Nanoparticle Monolayer Arrays Using an Anodic Aluminum Oxide Template.

Non-close-packed (NCP) silica nanoparticle monolayer arrays (SNMA) on ordered porous anodic aluminum oxide (AAO) templates were fabricated for the first time by a novel two-step spin-coating technique. The obtained NCP-SNMA-AAO was composed of silica nanoparticles (average primary particle size of 440 nm) and well-organized nanopores on the AAO substrates. NCP-SNMA-AAO with a supporting ratio of 87% silica nanoparticles showed a hydrophilic surface (water contact angle of 51.0°), while the original AAO substrate shows a hydrophobic surface (water contact angle of 107.9°). The maximum coefficient of static friction was decreased by 29% (0.327 → 0.233). The coefficient of dynamic friction was also decreased by 20% (0.281 → 0.226). We found that controlling the silica supporting ratio using the two-step spin-coating technique is an effective approach for surface modification of an AAO substrate.

Self-cleaning hydrophobic nanocoating on glass: A scalable manufacturing process

A method of forming a self-cleaning hydrophobic nanocoating (SCHN) on glass substrates utilizing a scalable manufacturing process is described. The process initiates with roughening of planar glass surfaces using diamond micro-/nano-particle abrasives, which creates microscopic tortuous grooves. After cleaning the substrates, the roughened surface is vapor deposited with trichloro (1H,1H,2H,2H-perfluorooctyl)silane (TCPFOS) under enclosure with controlled humidity. TCPFOS chemically binds with the substrate via covalent linkage. Due to the greatly reduced surface tension between water and the self-cleaning surface, the water droplet slides down leaving no trail (sliding angle of 14° for 0.1 mL water droplet). Due to the reduced adhesion of dirt to the self-cleaning surface, the dirt particles are washed away by sliding or rolling water droplets. The SCHN shows a negligible change in transmission as compared to the original glass substrate. The coating is resistant to multiple environmental factors including abrasion cycles, acid rain (pH = 3), saline exposure (10% w/v), alkali solution (pH 11, NaOH), and extreme temperature cycling (−10 to 60 °C).

Properties of cement-lime render containing perlite as lightweight aggregate

Lightweight renders with improved thermal performance, resistant against moisture and respecting specific behaviour of original plasters and substrates became attractive materials for surface finishing of both historical and old wall structures. In this respect, structural, mechanical and thermal properties of cement-lime based renders containing a different amount of perlite as fine silica sand substitution are researched in the presented paper. Experimental tests conducted for 28 days samples showed significant lightening of hardened renders with increased perlite content in their fresh mix. Gained strength parameters were, because of higher total open porosity of perlite enriched samples, lower compared with reference material. On the other hand, newly developed lightweight renders exhibited improved thermal insulation performance due to the highly porous perlite particles. In summary, cement-lime renders with incorporated lightweight aggregate based on expanded perlite were considered as alternative and promising materials for application in repair and restoration of historical masonry.

The effect chemical treatment of the substrate cadmium telluride on the quality of epitaxial structures

The etching of wafers of cadmium telluride in aqueous and nonaqueous solutions before the epitaxial process of building structures CdxHg1-xTe and its influence on the surface quality of epitaxial layers. As the etchants investigated 2—20 % solution of bromine in isobutyl alcohol, 5 % solution of bromine in methanol, dimethylsulfoxide, ethylene glycol, solutions of bromine in hydrobromic acid and mixed with glycerin, a saturated solution of potassium dichromate in sulfuric acid. The speed of etching was varied from 0.2 to 9 µm/min. Polishing Set nature of the etching substrate of cadmium telluride in 5 % solution of bromine in i-butanol, the dissolution process is diffusion in nature and is limited by the mass transfer of the reactants in the temperature range of 10—60 °C, depending on the concentration of bromine and the viscosity of the solution. Studied the morphology and surface finish of epitaxial layers of CdxHg1-xTe, depending on the method of etching the original substrate. Found the optimal compositions of etchants for precipitaciones processing of obtaining structures with a height of asperities of the surface at 0.1 atm.

Use of carbon stable isotopes to monitor biostimulation and electron donor fate in chromium-contaminated groundwater

Hexavalent chromium Cr(VI) is a common inorganic contaminant in industrial areas and represents a serious threat to human health due its toxicity. Here we report experimental results from a field-scale investigation of Cr(VI) bio-immobilization at Hanford 100H reservation, a U.S Department of Energy facility (Washington State, USA). Microbial Cr(VI) reduction was stimulated via injection of a13C-labeled sodium lactate solution into the high-permeability aquifer consisting of gravel and coarse sand sediments. Concentrations and carbon isotope ratios of metabolites, including dissolved inorganic carbon and total organic carbon, and compound-specific analysis of acetate and propionate, together with phospholipid fatty acids (biomass) have been analyzed to help provide an understanding of the predominant redox processes accompanying Cr(VI) reduction. Results of our study indicate that the injection of an electron donor caused a sharp decrease of Cr(VI) concentration from ∼32 to ∼10 nM. Cr(VI) reduction was associated with a decrease in the concentration of carboxylic acids, such as lactate (∼6 mM to undetectable), propionate (∼9 mM to undetectable), and acetate (∼6 mM to undetectable), as well as dissolved inorganic carbon (30–10 mM C). Carbon isotope data indicate carbon transfers from the original substrate to organic byproducts and mineralized carbon. Concentrations of metabolites and stable isotope data as well as carbon isotope mass balance calculations were used to monitor biologically mediated reduction of Cr(VI).

Baryte cohesive layers formed on a (010) gypsum surface by a pseudomorphic replacement

The mineral replacement of gypsum (CaSO4·2H2O) by baryte (BaSO4) is relevant to technological and industrial applications, including its use as a plaster or stone consolidant in cultural heritage conservation. In the present study, we provide experimental evidence suggesting that, during the interaction of gypsum cleavage surfaces with barium-bearing solutions, a pseudomorphic replacement takes place and results in the formation of a crystallographically oriented baryte layer. This mineral replacement process is favoured by the porosity generated, due to the differences in molar volume and solubility between parent and product sulfate phases, allowing the progress of the reaction. The homogeneous micrometre-sized layer of baryte occurs most likely via a fluid-mediated interface-coupled dissolution–precipitation mechanism. A certain degree of crystallographic control on the polycrystalline BaSO4 product layer by the structure of the parent substrate (gypsum) is confirmed by electron microscopy observations and X-ray diffraction analyses. The structural control exerted by the cleavage gypsum surface on the baryte layer can be defined by the epitactic relationship: Gyp (010) || Bar (010). The formation of baryte increases with reaction time until passivation occurs at the replacement interface, probably due to a decreased porosity and loss of connectivity that thereby prevents further reaction. The investigation of these processes occurring on freshly cleaved single crystals of gypsum were complemented by studying the replacement of polycrystalline gypsum cubes, showing a homogeneous baryte surface layer on the sample. The results of this study thus offer interesting insights into the application of the replacement of gypsum by baryte as a conservation method for gypsum sculptures and plasterwork, increasing their resistance against water and humidity while preserving the surface features of the original mineral substrate.

GaN-On-Diamond HEMT Technology With TAVG = 176°C at PDC,max = 56 W/mm Measured by Transient Thermoreflectance Imaging

Record DC power has been demonstrated in AlGaN/GaN high electron mobility transistors fabricated using a substrate replacement process in which a thick diamond substrate is grown by chemical vapor deposition following removal of the original Si substrate. Crucial to the process is a ~30 nm thick SiN interlayer that has been optimized for thermal resistance. The reductions obtained in self-heating have been quantified by transient thermoreflectance imaging and interpreted using 3D numerical simulation. With a DC power dissipation level of 56 W/mm, the measured average and maximum temperatures in the gate-drain access region were 176 °C and 205 °C, respectively.

Fluorometric and Colorimetric Dual-Readout Immunoassay Based on an Alkaline Phosphatase-Triggered Reaction.

Alkaline phosphatase (ALP) usually acts as a signal transmitter in enzyme-linked immunosorbent assay (ELISA); therefore, developing an attractive ALP activity assay, especially using a preferable substrate, would help improve the efficiency and convenience of ELISA in practical applications. Herein we have first prepared an original and creative substrate, named m-hydroxyphenyl phosphate sodium salt ( m-HPP), with a desirable dephosphorylation site for ALP. On the basis of the ALP-catalyzed hydrolysis of m-HPP to resorcinol and its subsequent specific nucleophilic reaction with dopamine, we have exploited a fluorometric and colorimetric dual-readout ALP activity assay and ALP-based ELISA system. Under the employed experimental conditions, highly sensitive and specific assay of ALP and cardiac troponin I (cTnI) has been accomplished in a straightforward way. Furthermore, the commendable sensing performance of our proposed ELISA in the determination of the cTnI level in diluted human serum unambiguously illustrates great potential in the early diagnosis of acute myocardial infarction.

An integrative approach for the selection of Pochonia chlamydosporia isolates for biocontrol of potato cyst and root knot nematodes.

The nematophagous fungus Pochonia chlamydosporia , a natural enemy of plant parasitic nematodes (PPN), has been exploited in the development of sustainable management strategies for PPN control. The intrinsic variation among P. chlamydosporia isolates affects biocontrol potential, so sound characterisation is required. Biological, molecular and metabolic analyses can be determinant in the screening and selection of these potential biological control agents. This study aimed to provide integrative characterisation of P. chlamydosporia isolates that can support isolate selection for biological control purposes. Eight Portuguese isolates, associated with Meloidogyne spp., were used as a case study. Isolates were identified and characterised: i) at the biological level through standard bioassays to evaluate their ability for rhizosphere colonisation, to produce chlamydospores, and to parasitise Globodera pallida and Meloidogyne incognita eggs; ii) at the molecular level, examining genetic variation using ERIC-PCR; and iii) at the metabolic level, assessing their metabolic profiles using Biolog FF MicroPlates, with concurrent reads of fungal utilisation of 95 different carbon sources. Molecular data and metabolic characterisation were reduced using Principal Component Analysis and compared with the biological characteristics. Molecular profiles could only be related to isolate geographical origin, but the original substrate (eggs or roots), parasitism of M. incognita eggs and ability for rhizosphere colonisation were correlated with metabolic profiles, indicative of utilisation of specific carbon sources. Meloidogyne egg parasitism and rhizosphere colonisation were related to each other. This integrative characterisation offers novel perspectives on the biology and biocontrol potential of P. chlamydosporia , and, once tested on a broader set of isolates, could be used to assist rapid isolate selection.

Ethanol Assisted Transfer for Clean Assembly of 2D Building Blocks and Suspended Structures

AbstractAs two dimensional materials (2D materials) demonstrate unique and diverse properties, clean transfer methods can serve a cornerstone for creative assembly of these 2D building blocks for both fundamental explorations and versatile applications. One of the major challenges for preserving the pristine properties of 2D materials during transfer and construction is to debond 2D materials from original substrates without inducing structural damage and external contamination. In this work, through both molecular dynamic studies and experimental demonstration, it is found that droplets of ethanol, a common and environmental friendly solvent, can be used to effectively reduce the adhesion energy between 2D materials and substrates, and therefore enable a clean transfer method for 2D mterials. Various assembled structures based on 2D building blocks, such as van der Waals heterostructures, predesigned artificial patterns, 2D materials on suspended devices are all demonstrated. Thermal conductivity measurements of MoS2 nanosheets on a suspended microbridge device also confirm the successful application of suspended 2D transfer. It is expected that this ethanol assisted transfer method can enable clean assembly of 2D building blocks for construction of novel structures and suspended devices.

The Effect of Damage of a Plasma-Treated Polyurethane Surface on Bacterial Adhesion

Abstract—Elastic polyurethanes are flexible materials used in biomedical products. Plasma treatment is a promising method of surface modification. However, external deformation of the elastic substrate could damage the modified layer and provoke various undesirable consequences. In this work, two elastic polyurethanes with different stiffness have been studied. The materials were treated by plasma immersion implantation of nitrogen ions (with the energy of 1 and 3 keV). As a result, the relief and hydrophobicity of the surfaces changed such that the adhesion of both Gram-positive (Staphylococcus) and Gram-negative (Escherichia coli) bacteria decreased. Cyclic uniaxial deformation damages the treated surfaces: transverse cracks and longitudinal folds are formed. These changes increase bacterial adhesion to values that exceeding that on untreated materials. All features of the modified surfaces correlated both with the properties of original substrate and with the treatment parameters. Bacterial adhesion is affected mainly by the peculiarities of the relief structure.