Substrates For Use Research Articles

Study of the effect of Persea americana seed in the green synthesis of silver nanoparticles and their antimicrobial properties

Abstract This work details the green synthesis of silver nanoparticles (Ag NPs) using different concentrations of Persea americana seed extract. UV–Vis absorption spectra showed the characteristic surface plasmon resonance band of Ag NPs at 430 nm. TEM micrographs showed that the size of the Ag NPs increased depending on the amount of extract used, presenting a tendency towards a spherical morphology. The antibacterial activity of the Ag NPs was studied using E. coli where the samples showed inhibitory effects at different silver concentrations. The biogenic Ag NPs promoted an increased methylene blue Raman signal demonstrating that they are a suitable substrate for use in Surface-Enhanced Raman Scattering (SERS).

Symmetric and asymmetric spiro-type colorless poly(ester imide)s with low coefficients of thermal expansion, high glass transition temperatures, and excellent solution-processability

In this work, we present several new poly(ester imide)s (PEsIs) with low coefficients of thermal expansion (CTE), excellent optical transparency, very high heat resistance (Tg), film ductility, and solution-processability. Symmetric and asymmetric spiro-type tetracarboxylic dianhydrides containing ester linkages (TA-s-Spiro and TA-a-Spiro) and diamines (AB-s-Spiro and AB-a-Spiro) were synthesized using xanthene-based isomeric bisphenols with a fluorenyl side group. The chemically imidized PEsIs were highly soluble in various common solvents including less polar non-amide solvents, and yielded stable solutions with high solid contents. The properties of the spiro-type PEsIs were systematically investigated and compared with those of the cardo-type counterparts. A PEsI derived from 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), AB-a-Spiro, and 2,2′-bis(trifluoromethyl)benzidine (TFMB) achieved outstanding combined properties, i.e., a very low CTE (10.5 ppm K−1), excellent optical transparency (YI = 3.4, T400 = 80.8%), a very high Tg (351 °C) and solution-processability. Thus, the PEsIs are promising candidates as novel plastic substrates for use in image display devices. The isomer effects on the properties were also investigated and a possible mechanism for these effects is proposed.

Templated Synthesis of Ultrafine Polyaniline Fibers and Their Transfer to Carbon Substrates for Highly Rapid Redox Reactions

AbstractPolyaniline ultrafine fibers (PANI‐UFs) prepared using commercial activated carbon (AC) as a template are transferred to conductive carbon substrates. This method starts with the adsorption of aniline in AC, followed by its subsequent electrochemical polymerization to produce PANI‐UFs inside the AC pores. The resulting PANI‐UFs can be transferred onto carbon substrates under an applied potential. In this study, two kinds of AC with different pore sizes (≈2 and ≈4 nm) are used, and carbon black, graphite rods, highly oriented pyrolytic graphite, and stainless steel are examined as conductive substrates. It is found that the transfer of PANI‐UFs fails only in the case of stainless steel. The transfer of PANI‐UFs cannot be confirmed by transmission electron microscopy observation because of their ultrafine structures. However, their existence is confirmed by energy dispersive X‐ray spectroscopy, atomic force microscopy, and electrochemical analyses. The electrochemical analyses reveal that the electrochemical behavior of the PANI‐UFs is not affected by the pore size of the AC template. In addition, the PANI‐UFs are characterized by extremely rapid redox responses. This template method can be applied for the fabrication of PANI‐UFs on versatile conductive carbon substrates for use in highly sensitive sensors and other electronic devices.

Study on the Main Influencing Factors in the Removal Process of Non-Stick Fluoropolymer Coatings Using Nd:YAG Laser.

The coatings with fluoropolymer resins rich in fluorinated ethylene propylene (FEP) and polytetrafluoroethylene (PTFE) are applied as anti-adherent coatings on aluminum–magnesium substrates for use in food containers. In many cases, due to wear, they must be stripped for the application of a new coating on the same substrate. There are several processes for this: blasting, plasma, pyrolysis, chemical processes, laser, high pressure water, and combinations of these. This work focuses on the characterization of the main factors that condition the FEP coating removal process by a continuous wave (CW) Nd:YAG laser, and on the determination of the efficiency of this type of technology used for this purpose. Stripping surface per unit of time and energy consumption per unit area has been determined among other efficiency indicators. Regarding the characterization of the coating object of study, its thickness, surface roughness, contact angle, microhardness and absorbance-reflectance responses have been determined, and the results have been compared with those obtained in the case of PTFE. In addition, to evaluate the mechanical damage caused in the substrate after coating removal by (CW) Nd:YAG laser, the tensile strength, Vickers hardness, Ra and Rz roughness, and the substrate thickness have been measured and analyzed.

Methods of Synthesis and Characterization of Conductive DNA Nanowires Based on Metal Ion-Mediated Base Pairing for Single-Molecule Electronics

Advances in the field of molecular electronics have made possible the directmeasurement of charge transport across single molecules. In particular, workon DNA oligomers has demonstrated that this weakly-conducting biomoleculecan be functionalized through metal-mediated nucleobase pairing in order tosignificantly increase electron mobility across the molecule. The introductionof interacting stacks of single metal ions inside the DNA helix is an attractiveplatform for assay and optimization; for this reason we present a protocolfor the production and processing of nanowires with a metal base pair forsingle-molecule applications. In particular, we describe the construction of DNA duplex wires with a cytosine-Ag+-cytosine base pair (dC:Ag+:dC).A thorough investigation of buffer components suggests the use of divalentmagnesium counterions to stabilize highly mismatched oligonucleotides insolution. We further analyse cleaning and processing of thin gold films forbatch-fabrication of conductive imaging substrates for use in conductivescanning probe assays of single-molecule conductivity. With a clear path toelectrical assays, we suggest that the C:Ag+:C orthogonal nucleotide pair andother similar chemistries may provide a foundation for molecular electroniccomponents in integrated devices

Quantitative analysis of sound absorption properties of plants in indoor environment for enabling sustainable practices

This paper showcases the results of the sound attenuation properties of some plants with a soil substrate for use as green sound absorbers in an indoor space. The plants used in this experiment were needed to survive in an indoor environment, hence only tropical, thermophilic plants which could grow in high humidity and warm temperatures with indirect sunlight were selected. An impedance tube of 100 mm dia. was used to calculate the direct incidence acoustic absorption coefficient of the plants and larger samples were tested within a reverberation chamber. The soil substrate used was a high porosity and low-density sample of perlite and coconut fibres. The results show that ferns and baby tears were good absorbers along with the soil substrate, whereas begonia was a better absorber at the lower and higher frequencies. The decibel drop by the fern with soil substrate is the highest with a decrease of frequency and the lowest is by Green Ivy which is due to morphological conditions.

Quantitative analysis of sound absorption properties of plants in indoor environment for enabling sustainable practices

This paper showcases the results of the sound attenuation properties of some plants with a soil substrate for use as green sound absorbers in an indoor space. The plants used in this experiment were needed to survive in an indoor environment, hence only tropical, thermophilic plants which could grow in high humidity and warm temperatures with indirect sunlight were selected. An impedance tube of 100 mm dia. was used to calculate the direct incidence acoustic absorption coefficient of the plants and larger samples were tested within a reverberation chamber. The soil substrate used was a high porosity and low-density sample of perlite and coconut fibres. The results show that ferns and baby tears were good absorbers along with the soil substrate, whereas begonia was a better absorber at the lower and higher frequencies. The decibel drop by the fern with soil substrate is the highest with a decrease of frequency and the lowest is by Green Ivy which is due to morphological conditions.

Microstructure and Corrosion Behavior of Thermal-Sprayed Hydroxyapatite/Magnesium Composite Coating on the Surface of AZ91D Magnesium Alloy

To slow down the corrosion rate and increase the bioactivity of magnesium alloys, biodegradable hydroxyapatite/magnesium (HA/Mg) composite coating was deposited onto AZ91D alloy substrate by high-velocity suspension flame spray technique using nano-sized HA and micron-sized Mg powders. Microstructures and phase constitutions of HA/Mg composite coating were analyzed by scanning electron microscopy and x-ray diffraction. Corrosion resistance of composite coating was also evaluated by potentiodynamic polarization test and electrochemical impedance spectroscopy in Hanks’ balanced salt solution (HBSS). The result shows that the HA/Mg composite coating mainly consisted of Mg and HA in addition to a few of MgO phases. The coating showed a rough surface morphology with homogeneous elemental distribution and a lamellar structure in cross section as well as well-bonded coating/substrate interface. Mg particles presented superior deposition during spraying due to their higher melting degree compared to HA particles. AZ91D alloy substrate was significantly protected from corrosion in HBSS by the HA/Mg composite coating with Mg dissolution on surfaces of the composite coating. This strategy can offer a new route to fabricate HA/Mg composite coatings on other metal substrates for use in biodegradable implant fields.

An internally quenched peptide as a new model substrate for rhomboid intramembrane proteases.

Rhomboids are ubiquitous intramembrane serine proteases that cleave transmembrane substrates. Their functions include growth factor signaling, mitochondrial homeostasis, and parasite invasion. A recent study revealed that the Escherichia coli rhomboid protease EcGlpG is essential for its extraintestinal pathogenic colonization within the gut. Crystal structures of EcGlpG and the Haemophilus influenzae rhomboid protease HiGlpG have deciphered an active site that is buried within the lipid bilayer but exposed to the aqueous environment via a cavity at the periplasmic face. A lack of physiological transmembrane substrates has hampered progression for understanding their catalytic mechanism and screening inhibitor libraries. To identify a soluble substrate for use in the study of rhomboid proteases, an array of internally quenched peptides were assayed with HiGlpG, EcGlpG and PsAarA from Providencia stuartti. One substrate was identified that was cleaved by all three rhomboid proteases, with HiGlpG having the highest cleavage efficiency. Mass spectrometry analysis determined that all enzymes hydrolyze this substrate between norvaline and tryptophan. Kinetic analysis in both detergent and bicellular systems demonstrated that this substrate can be cleaved in solution and in the lipid environment. The substrate was subsequently used to screen a panel of benzoxazin-4-one inhibitors to validate its use in inhibitor discovery.

Floriferous herbaceous and substrates for use on extensive green roofs

In general, extensive green roofs are defined as all cover covered with herbaceous vegetation and surface substratum, however, in Brazil there are few information regarding the materials for installation and maintenance of these systems, being essential the search for better species and substrates adapted to the tropical conditions. Thus, the objective was to evaluate the performance of floriferous herbaceous and substrates for use in extensive green roofs. The experiment was carried out in the field and in full sunlight, in black plastic containers (8.46 L and 15.5 cm high), elevated 90 cm from the ground, in a 3x2 factorial scheme. Being 3 herbaceous floriferous species (Torenia var. Kauai, Periwinkle var. Pacifica XP and Petunia var. Bacopa) and 2 substrates [S1-Charcoal + pine bark + peat + expanded vermiculite (1v:1v:1v:1v) and S2- Coconut fiber + carbonized rice husk + peat + expanded vermiculite (1v:1v:1v:1v)], with 3 replicates per treatment. It was evaluated in the substrates: pH, electrical conductivity, macro and microporosity, total porosity, density and water retention capacity. For the development of the species, 60 days after the experiment installation, were evaluated, chlorophyll content of leaves, number of flowers and vegetation surface temperature. It was observed that the substrate S2 presented the best results in the physico-chemical analyzes, and this possibly came to reflect on the performance of the species, and that Torenia when cultivated in this substrate had the highest chlorophyll content (42.67 SPAD). The number of flowers was statistically the same for Torenia and Periwinkle in both substrates, while the three floriferous herbaceous plants showed a decrease in surface temperature. Thus, it is recommended for use on extensive green roofs the substrate composed of coconut fiber + carbonized rice husk + peat + expanded vermiculite (1v:1v:1v:1v), and the floriferous herbaceous Torenia var. Kauai.

Facile preparation of graphene coated copper electrodes via centrifugal milling for capacitive deionization applications

This work presents the simple synthesis and simultaneous deposition of graphene nanoplatelets onto pure copper substrates for use as capacitive deionization electrodes. Copper is cheap and abundant material that can easily be fabricated into electrodes but suffers from high reactivity in solution with unpredictable consequences. The deposition of turbostratic graphene layer using the proposed high energy centrifugal milling technique introduces a chemically inert, but electrically conductive surface layer that extends the operational lifetime of the copper working electrode many folds compared to the bare pure copper one. In the trials presented here the operation of the pure copper electrode degraded almost instantly as the electrochemical cell was activated, compared to a smooth 60-minute operation of its graphene-coated counterpart. The graphene electrode was successful in reducing the solution conductance by more than 12% for the test period, which renews the interest in copper as an effective counter electrode for capacitive deionization applications. The quality of graphene deposition is verified via Raman spectroscopy, while the characterization of the copper chloride is done via X-ray Diffraction. The deionization process resulted in the production of Cu2Cl(OH)3 deposits on the copper electrode, which is mentioned as a viable method of producing it, although it is an unexpected result of this work.

Facile hydrothermal synthesis of NiCo2O4- decorated filter carbon as electrodes for high performance asymmetric supercapacitors

A simple hydrothermal method is developed for the growth of NiCo2O4 nano-needle arrays on a filter paper carbon (FC) substrate for use as a high performance electrode for supercapacitors. The as-synthesized NiCo2O4/C composites exhibited high specific capacitance (995.2 F g−1 at a current density of 10 A g−1) and excellent cycling performance (no capacitance loss after 3000 cycles). The 3D framework of the FC substrate not only prevents the aggregation of NiCo2O4 nanoparticles, but also improves its electrical conductivity, thus leading to excellent electrochemical performance. Moreover, an asymmetric supercapacitor was assembled by using the NiCo2O4/C composites and activated carbon as the positive and negative electrode, respectively, and provided a maximum energy density of 20.87 Wh kg−1 at a power density of 374.6 W kg−1 and a maximum power density of 7.48 kW kg−1 at an energy density of 11.43 Wh kg−1 within a potential window of 0–1.5 V, demonstrating the potential of the composites for use in high performance energy storage systems.

A thorough study on electrochromic properties of metal doped tungsten trioxide film prepared by a facile solution process

In this research, we investigate the effect of metal doping on the electrochromic (EC) performance of tungsten trioxide (WO3) films. These films were prepared by a novel method involving solution processing and thermal annealing. In this procedure, ammonium tetrathiotungstate ((NH4)2WS4) was dissolved in dimethylformamide at a high concentration ratio (200 mg mL−1) to obtain a homogeneous solution and then spin-coated onto the indium thin oxide (ITO) substrate for use as a working electrode. Subsequently, the film was annealed at the different temperatures (200, 300, 400, and 500 °C) to form a crystal structure of WO3. X-ray diffraction, Raman, and X-ray photoelectron spectroscopic results confirm the crystal formation of WO3. Moreover, in order to improve the electrochromic performance, different concentrations (10, 20, 30, and 40 mM) of different metal chlorides such as PtCl4, PdCl2, AuCl3, AgCl, CuCl2, NiCl2, NaCl, and KCl were added into the (NH4)2WS4 precursor and the mixture was coated on the ITO substrate and annealed at 500 °C. The results indicate that the performance of the Au-doped WO3 film was better than those with other dopants, likely as a result of the plasmonic effect. Therefore, the proposed method and Au-doped WO3 films are great candidates for the development of smart windows with high EC performance.

Awareness, use and Satisfaction of Dental Assistants of Iranian Medical Digital Library

: Digital libraries provide suitable substrates for use in the field of electronic information resources. Obtain and introduce of electronic resources to targets may be challenging for operators. Thus, the objective of this study is to determine awareness, use and Satisfaction of dental assistants of Iranian Medical Digital Library.

Deposition and characterization of ITO thin film over glass for defogger application and for solar photovoltaics

Indium thin oxide (ITO) films have been used in solar cell applications as top conducting layers for many years. These films possess very good transmission and a low sheet resistance thus making them ideal candidate material for top conducting layers in thin film and HIT solar cells. In the present work, ITO films have been deposited over soda lime glass substrates for use as defogger applications, and for use as front contact electrode in HIT type solar cells as well. ITO deposition is done using pulsed DC sputtering technique inside a vacuum chamber with large size ITO sputtering target of 15 inches by 5 inches. Silver bus bars are printed at the two edges of glass using thick film screen printing technique and the firing of thick film is done in a belt furnace. The deposited ITO thin film characterization is done by using XRD, SEM and 4 probe sheet resistance measurement techniques. The transmission spectra is analyzed for optical transmission properties.

Fabrication of a light-intensity-enhancement component by using computer-controlled ultraviolet curing and air-pressing imprinting

In this study, the ultraviolet (UV) curing and air pressure imprinting methods are proposed for the fabrication of a light-intensity-enhancement component. The air-pressing process provides a uniform embossing pressure, and the UV curing module enables the process to be performed at room temperature and low pressure. Because the UV resin is sensitive to the process parameters, such as the curing time and pressing pressure, the liquid resin must be filled at a precise pressure. To control the precision, the UV embossing facility comprised a resin-dispensing system, air-pressing system, and UV curing system. These systems were controlled by the Arduino system. In the Arduino system, the computer-controlled input can eliminate artificial errors and each forming step can be programed into one script to achieve automation. In this study, V-groove microstructures were formed. The V-groove pattern was replicated with a width of 47 μm and height of 22 μm on polymethyl methacrylate substrate for use as a light guiding panel. The proposed methodology enables automatic control of the UV microscale imprinting process.

Broadband Solar Absorption Enhancement in a Silver–Epoxy Nanocomposite for Use as Selective Coating

This paper reports the optical properties of a black silver–epoxy nanocomposite deposited on copper substrate for use as selective solar absorber. The silver nanoparticles at 3 wt% have been formed in situ in an epoxy resin in presence of organic solvent at room temperature. The nanocomposite exhibited a strong broadband light absorption in the entire visible spectrum. Atomic force microscopy images showed mixtures of spherical and elongated nanoparticles very close together (spacing much smaller than light wavelength) and predominantly clusters of them. The origin of the wide-band absorption is due to the superposition of all excitations of dipole and high-order modes coming from nanoparticles of different diameters (of 10–80 nm) and elongations (length of 80–500 nm). In order to evaluate the solar optical properties, the black silver–epoxy nanocomposite was deposited on copper substrate by the roll coating method and subsequently thermocured in air at 100 °C. The spectral data of the thermocured coatings in air showed significant decrease of the reflectance (< 13%) in the wavelength region from 200 to 1300 nm. The reduction in reflectance is explained in terms of the light trapping by forward scattering in the nanoparticles. The silver–epoxy nanocomposite deposited on a metal substrate for use as solar selective absorber is very attractive due to the easiness of its deposition, very good adherence, low-cost processing, high thermal stability, and low weight of coating per square meter of substrate (1.4 g/m2), and finally, it can be applied over large substrate areas.

Macroporous Ni foam-supported Co3O4 nanobrush and nanomace hybrid arrays for high-efficiency CO oxidation

Herein, we reported the synthesis of well-defined Co3O4 nanoarrays (NAs) supported on a monolithic three-dimensional macroporous nickel (Ni) foam substrate for use in high-efficiency CO oxidation. The monolithic Co3O4 NAs catalysts were obtained through a generic hydrothermal synthesis route with subsequent calcination. By controlling the reaction time, solvent polarity and deposition agent, these Co3O4 NAs catalysts exhibited various novel morphologies (single or hybrid arrays), whose physicochemical properties were further characterized by using several analytical techniques. Based on the catalytic and characterization analyses, it was found that the Co3O4 NAs-6 catalyst with nanobrush and nanomace arrays displayed enhanced catalytic activity for CO oxidation, achieving an efficient 100% CO oxidation conversion at a gas hourly space velocity (GHSV) 10,000hr−1 and 150°C with long-term stability. Compared with the other Co3O4 NAs catalysts, it had the highest abundance of surface-adsorbed oxygen species, excellent low-temperature reducibility and was rich in surface-active sites (Co3+/Co2+=1.26).

Optically transparent aromatic poly(ester imide)s with low coefficients of thermal expansion. 2: Effect of the introduction of alkyl‐substituted p‐biphenylene units

AbstractA series of ester‐linked tetracarboxylic dianhydrides (TA‐X) were synthesized from trimellitic anhydride chloride and 4,4′‐biphenol analogs containing different numbers and positions of methyl substituents. Aromatic poly(ester imide)s (PEsIs) were polymerized from TA‐Xs and 2,2′‐bis(trifluoromethyl)benzidine to investigate the film properties systematically. A significant substituent effect on the target properties (Tg, optical transparency, the linear coefficient of thermal expansion (CTE) and ductility) was observed. A PEsI containing 2,2′,3,3′,5,5′‐hexamethyl‐substituted p‐biphenylene units was chemically imidized in a homogeneous state. It was highly soluble at room temperature, even in less hygroscopic non‐amide solvents such as cyclopentanone (CPN), and provided a stable CPN solution with a high solid content. The CPN‐cast PEsI film was almost colorless as suggested from the rather low yellowness index (3.2), high light transmittance at 400 nm (71.5%) and very low haze (1.15%). This PEsI film also had a high Tg (294 °C, determined by thermomechanical analysis) in addition to a low CTE (21.7 ppm K−1), moderate film ductility and very low water uptake. A structural modification of the PEsI by copolymerization with a tetracarboxylic dianhydride with a rigid/linear structure was effective in further reducing the CTE while maintaining the other excellent target properties. Thus, some of the PEsIs developed in this work are promising candidates as novel plastic substrates for use in image display devices. © 2017 Society of Chemical Industry

Direct Interfacial Electron Transfer from High-Potential Porphyrins into Semiconductor Surfaces: A Comparison of Linkers and Anchoring Groups

This study probes a series of linkers and anchoring groups for direct interfacial electron transfer (IET) from high-potential porphyrins into semiconductor surfaces. Eight different linker–anchor combinations of CF3-substituted, high-potential porphyrins were designed, synthesized, and characterized. Specifically, a series of four anchors was examined (carboxylate, hydroxamate, phosphonate, and silatrane), along with two different linkers (phenylene and benzanilidylene), which differ in terms of their electronic conjugation and overall length. The electrochemical and photophysical properties of the porphyrins were evaluated by steady-state and transient spectroscopies in solution and on mesoporous SnO2 substrates for use as dye photosensitizers in aqueous photoelectrochemical cells. IET dynamics were measured using time-resolved terahertz (TRTS) and transient absorption spectroscopies. From TRTS measurements, injection yields were determined relative to a commonly used phosphonated ruthenium(II) polypyrid...