Air Spray Deposition Research Articles

Enhanced separation performance of composite nanofiltration membranes via electrostatic air spray PSS/PEI interlayer

Thin-film composite (TFC) membranes with an interlayer were prepared extensively for desalination, but the hydrophilicity and permeability were not well improved. In this work, a smooth and hydrophilic interlayer was constructed by electrostatic air spray deposition (EASD) of poly (sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) on the polyethersulfone substrate and an ultra-thin separation layer was prepared using interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) to acquire high-performance composite nanofiltration (NF) membranes. The polymer solution was atomized into tiny particles under a high-pressure electrostatic air spray effect, facilitating the deposition of PSS/PEI with good homogeneity and enabling a denser and smoother interlayer surface. The introduction of PSS/PEI enhanced the hydrophilicity of TFC membranes and increased the repulsion of divalent cations to improve the salt rejection. The impacts of PEI concentration and EASD time on the separation performance of NF membrane were explored. The optimized TFC-3 NF membrane had a permeate flux of 74.5 ± 1.6 L·m−2·h−1 under 0.5 MPa, which was 2.5 times higher than the water flux of conventional TFC-0 membrane, while retaining up to 99.2 ± 0.5 % of Na2SO4. This work provides a prospective strategy to develop high-performance TFC membranes with great extensive progress for seawater purification.

Fabrication of Magnetic Responsive Surface with Multiscale Microstructures by Electrostatic Air Spray Deposition

Fabrication of Magnetic Responsive Surface with Multiscale Microstructures by Electrostatic Air Spray Deposition

Magnetically Responsive Superhydrophobic Surface with Switchable Adhesivity Based on Electrostatic Air Spray Deposition

A new method was reported for preparing a magnetically responsive superhydrophobic surface by electrostatic air spray deposition (EASD) and magnetic induction. The mixture was fully atomized under the combined action of the electrostatic field and the high-speed airflow field, and a dense array of micropillars was formed. The atomization mechanism of EASD was explored. The distribution and physical parameters of the micropillars were evaluated and counted. Switchable adhesion characteristics of the surface and the reversibility in 10 cycles were examined. The influences of different electrostatic voltages, component concentration, spray distance, air pressure, and magnetic field intensity on the surface morphology and hydrophobicity were analyzed. The prepared surface can be reversibly transformed between the high-adhesion state (with a contact angle of 108°) and the low-adhesion state (with a contact angle of 154°) by on/off switching of an external magnetic field. After a 2.2 kPa pressure load was applied, the surface contact angle was 144° with an applied magnetic field of 0.4 T. After heated at 90 °C for more than 90 min, the surface can almost obtain superhydrophobicity (with a contact angle of 148°) in the absence of a magnetic field. By utilizing the switchable surface adhesion characteristics, various kinds of droplet transmissions were realized. When the cured surface was spray-coated with carbon nanoparticles (CNPs), active droplet manipulation can be achieved by simply moving the magnet. The advantages of this method include a simple preparation process without chemical surface modification.

Synthesis and characterization of Cu-doped ZnO/RGO nanocomposites for room-temperature H2S gas sensor

Abstract The development of low or room temperature gas sensors having a response towards a particular target gas becomes a fascinating research topic for low power consumption applications. In this paper, a sensitive room-temperature hydrogen sulfide (H2S) gas sensors based on hydrothermally synthesized undoped zinc oxide (ZnO) and Cu-doped ZnO (CZO) nanostructures decorated with reduced graphene oxide (RGO) are successfully demonstrated. A simple air-spray deposition is employed as an effective method for uniform GO decoration on CZO nanostructured film which is further chemically reduced to form RGO. The influence of Cu-doping on crystallinity, surface-morphological, and chemical compositional properties of the material have been systematically investigated. The gas sensing properties of the synthesized nanocomposite sensors have been studied towards H2S at room temperatures (∼24 °C). Compared with undoped ZnO/RGO, 3CZO/RGO nanocomposite sensor exhibited a better response towards H2S. The sensor response increases almost linearly with the increase in H2S gas concentration and exhibits the evident response of 0.87%–100 ppm H2S at 24 °C with the response and recovery time of 14 and 32 s, and a theoretical limit of detection of about 136 ppb. The enhancement was accredited to the collegial effect of both Cu dopant and RGO. The sensor also shows good selective behavior towards H2S against H2. The H2S sensing mechanism associated with the p-type behavior of the 3CZO/RGO sensor is also discussed at length.

Scalable and Universal Route for the Deposition of Binary, Ternary, and Quaternary Metal Sulfide Materials from Molecular Precursors.

A range of binary, ternary (CFS), and quaternary (CZTS) metal sulfide materials have been successfully deposited onto the glass substrates by air-spray deposition of metal diethyldithiocarbamate molecular precursors followed by pyrolysis (18 examples). The as-deposited materials were characterized by powder X-ray diffraction (p-XRD), Raman spectroscopy, secondary electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy, which in all cases showed that the materials were polycrystalline with the expected elemental stoichiometry. In the case of the higher sulfides, EDX spectroscopy mapping demonstrated the spatial homogeneity of the elemental distributions at the microscale. By using this simple and inexpensive method, we could potentially fabricate thin films of any given main group or transition metal chalcogenide material over large areas, theoretically on substrates with complex topologies.

Effects of Aluminum Fin Thickness Coated with a Solar Paint on the Thermal Performance of Evacuated Tube Collector

In commercial evacuated tube collector (ETC) with double layers evacuated tube, a solar absorber is coated on the outer surface of the inner glass vacuum tube. In order to reduce cost of production and maintenance, our previous research work has been successfully initiated to place an aluminum fin inside the ETC to be a solar receiver together with clear double layers evacuated tube. Therefore, the objective of this present research is focused on the effect of aluminum (Al) fin thickness coated with solar paint on the thermal performance of ETC. Commercial Al fins with three different thicknesses (11, 13, and 24 µm) were considered in this study. An available solar paint (Thurmolax 250 selective black solar collector coating) was coated on the Al fin solar absorber using an air spray deposition technique with three different coating thicknesses. Spectral reflectance and thickness of the coatings were characterized using Ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometer at the wavelengths 300-2500 nm and a Mini Test 730 equipment respectively. The solar absorptance (α) was calculated based on the relationship of observed reflectivity (R), and the solar spectral irradiance of AM 1.5 in the whole wavelength range of the solar spectrum. The collector thermal efficiency (η) of ETC with different thicknesses of Al fin coated with solar paint as solar receiver was evaluated, following a standard ISO 9806-1. As a result, it is found that the α of all the thicknesses of solar paints considered was identical (α=0.94), indicating that the thickness of solar paint was an insignificant effect on the α. The η, heat removal factor ( FR), and overall heat loss coefficient (UL ) were calculated for different Al fin thicknesses with 1x solar paint coating thickness and were found to be increasing with decreased Al fin solar absorber thickness. The results revealed that the FR was predominant for the increase in the η with the reduction of Al fin solar absorber thickness. It can be concluded that the thinner Al fin (11µm) with single layer solar paint coating is suggested to be used in ETC due to its relatively higher η and FR, including light weight and low cost.

A hybrid aerodynamic and electrostatic atomization system for enhanced uniformity of thin film

Droplet deposition processes by the mechanisms of either aerodynamics or electrostatic spray have been widely studied in various applications such as aerosol generators, thin film coatings, and nanoparticle formations. Among the current state-of-art methodologies, air spray deposition can produce small-sized droplets without fine control on their sizes and uniformity in deposited thin films. Conventional electrospray depositions, on the other hand, can fabricate thin films with good uniform with a relatively slow deposition speed. In this paper, a hybrid mechanism by means of aerodynamic and electrostatic deposition is investigated and demonstrated to allow high throughput and improved uniformity for thin film depositions. It utilizes both the electrostatic force and aerodynamic force to atomize the liquid and control the droplet spraying process with good stability/repeatability. A uniform thin TiO2 film has been deposited as the demonstration example using this method. The velocities and trajectories of droplets during the deposition process have been characterized under different experimental parameters by using the technique of particle image velocimetry (PIV). This hybrid thin film fabrication method could be applicable in several industrial processes for better uniformity in making transparent electrodes, solar cells, displays, and automobiles.

Adhesion profile and differentiation capacity of human adipose tissue derived mesenchymal stem cells grown on metal ion (Zn, Ag and Cu) doped hydroxyapatite nano-coated surfaces

Accelerated Mesenchymal Stem Cells (MSCs) condensation and robust MSC-matrix and MSC-MSC interactions on nano-surfaces may provide critical factors contributing to such events, likely through the orchestrated signal cascades and cellular events modulated by the extracellular matrix. In this study, human adipose tissue derived mesenchymal stem cells (hMSC)', were grown on metal ion (Zn, Ag and Cu) doped hydroxyapatite (HAP) nano-coated surfaces. These metal ions are known to have different chemical and surface properties; therefore we investigated their respective contributions to cell viability, cellular behavior, osteogenic differentiation capacity and substrate-cell interaction. Nano-powders were produced using a wet chemical process. Air spray deposition was used to accumulate the metal ion doped HAP films on a glass substrate. Cell viability was determined by MTT, LDH and DNA quantitation methods Osteogenic differentiation capacity of hMSCs was analyzed with Alizarin Red Staining and Alkaline Phosphatase Specific Activity. Adhesion of the hMSCs and the effect of cell adhesion on biomaterial biocompatibility were explored through cell adhesion assay, immunofluorescence staining for vinculin and f-actin cytoskeleton components, SEM and microarray including 84 known extracellular matrix proteins and cell adhesion pathway genes, since, adhesion is the first step for good biocompability. The results demonstrate that the viability and osteogenic differentiation of the hMSCs (in growth media without osteogenic stimulation) and cell adhesion capability are higher on nanocoated surfaces that include Zn, Ag and/or Cu metal ions than commercial HAP. These results reveal that Zn, Ag and Cu metal ions contribute to the biocompatibility of exogenous material.

High performance all-carbon composite transparent electrodes containing uniform carbon nanotube networks

Indium tin oxide-free, flexible transparent electrodes (TEs) are crucial for the future commercialization of flexible and wearable electronics. While carbon-based TEs containing carbon nanotube (CNT) networks show promise, they usually exhibit poor dispersion properties, limiting their performance and practicality. In this study, we report a highly efficient and bending durable all-carbon composite TE (ac-TE) that employs uniform CNT networks on a monolayer graphene/polyethylene terephthalate (PET) substrate via a simple air spray deposition method. The air-sprayed CNT/graphene assembly was free-standing on solution, making a polymer-free transfer of carbon composites to target substrates possible. The excellent performance of the ac-TEs was attributed to the uniformly networked CNTs on the polycrystalline graphene with a well-controlled density, effectively bridging the line defects and filling the tears/voids or folds necessarily existing in the as-processed graphene. The sheet resistance of the ac-TEs was increased only 6% from its original value at a bending radius of 2.7 mm, while that of the pristine graphene/PET assembly increased 237%. Mechanical bending of the ac-TEs worsened the electrical performance by only ∼1.7% after 2000 bending cycles at a bending radius of 2.5 mm. Degradation of the performance by the bending was the result of line defects formation in the graphene, demonstrating the potential of the uniform CNT networks to achieve more efficient and flexible carbon-based TEs. Furthermore, the chemically-doped ac-TEs showed commercially suitable electronic and optical properties with much enhanced thermal stability, closer to practical TEs in flexible devices.

Conductive coatings with low carbon-black content by adding carbon nanofibers

Abstract Conductive coatings based on low carbon-black content by adding carbon nanofibers are obtained in a silica matrix obtained by the sol–gel process. The carbon nanofibers incorporation allows reducing the percolation threshold down to 20 wt.% of carbon black into the silica matrix obtaining good electrical properties. Coatings are deposited by air-spray deposition onto tile substrates and sintered in the temperature range of 300–500 °C in air atmosphere. The coatings achieve resistivities as low as 2 × 10 −3 Ωm due to the percolation between the carbon black nanoparticles and carbon nanofibers which improves the conductive paths. The samples are microstructural characterized by Scanning Electron Microscopy and Confocal Raman Spectroscopy. The electrical properties are measured by impedance spectroscopy. The thermal properties derived of the Joule effect are measured using DC intensity–voltage curves and thermal infrared camera, and it is observed a nearly linear relationship between electric power and temperature increasing in the measured range. Thereby, a wide range of application is opened by means of tailoring the electrical response of the coatings: higher resistivity coatings produce thermal heating above 90 °C, appropriated for electric heaters, and conductive coatings are suitable for electronic devices, electrodes and EMI/RFI shielding.

Formal Lithium Fixation Improves Direct Analysis of Lipids in Tissue by Mass Spectrometry

Mass spectrometry imaging is a powerful method for imaging and in situ characterization of lipids in thin tissue sections. Structural elucidation of lipids is often achieved via collision induced dissociation, and lithium-lipid adducts have been widely reported as providing the most structurally informative fragment ions. We present a method for the incorporation of lithium salts into tissue imaging experiments via fixation of samples in formal lithium solutions. The method is suitable for preparation of single tissue sections, or as an immersion fixation method for whole tissue blocks or organs prior to sectioning. We compare lithium adduct detection and MALDI-MSI of murine brain from analysis of tissues prepared in different ways. Tissues prepared in formal solutions containing lithium or sodium salts before coating in matrix via air-spray deposition are compared with fresh samples coated in lithium-doped matrix preparations by either dry-coating or air-spray deposition. Sample preparation via fixation in formal lithium is shown to yield the highest quality images of lithium adducts, resulting in acquisition of more informative product ion spectra in MALDI MS/MS profiling and imaging experiments. Finally, the compatibility of formal lithium solutions with standard histological staining protocols (hemotoxylin and eosin, Van Giessen and Oil Red O) is demonstrated in a study of human liver tissue.

Matrix‐assisted laser desorption/ionization imaging mass spectrometry for direct measurement of clozapine in rat brain tissue

Matrix-assisted laser desorption/ionization hyphenated with quadrupole time-of-flight (QTOF) mass spectrometry (MS) has been used to directly determine the distribution of pharmaceuticals in rat brain tissue slices which might unravel their disposition for new drug development. Clozapine, an antipsychotic drug, and norclozapine were used as model compounds to investigate fundamental parameters such as matrix and solvent effects and irradiance dependence on MALDI intensity but also to address the issues with direct tissue imaging MS technique such as (1) uniform coating by the matrix, (2) linearity of MALDI signals, and (3) redistribution of surface analytes. The tissue sections were coated with various matrices on MALDI plates by airspray deposition prior to MS detection. MALDI signals of analytes were detected by monitoring the dissociation of the individual protonated molecules to their predominant MS/MS product ions. The matrices were chosen for tissue applications based on their ability to form a homogeneous coating of dense crystals and to yield greater sensitivity. Images revealing the spatial localization in tissue sections using MALDI-QTOF following a direct infusion of (3)H-clozapine into rat brain were found to be in good correlation with those using a radioautographic approach. The density of clozapine and its major metabolites from whole brain homogenates was further confirmed using fast high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) procedures.

Determination of pharmaceutical compounds in skin by imaging matrix‐assisted laser desorption/ionisation mass spectrometry

Matrix-assisted laser desorption/ionisation (MALDI) quadrupole time-of-flight mass spectrometry (Q-TOFMS) has been used to detect and image the distribution of a xenobiotic substance in skin. Porcine epidermal tissue was treated with 'Nizoral', a medicated shampoo containing ketoconazole (+/-)-1-acetyl-4-[p-[[(2R,4S)-2-(2,4-dichlorophenyl)-2-(imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl]piperazine) as active ingredient. Following incubation for 1 h at 37 degrees C all excess formulation was washed from the surface. A cross-section of the drug-treated tissue was then blotted onto a cellulose membrane, precoated in matrix (alpha-cyano-4-hydroxycinnamic acid (CHCA)), by airspray deposition. In separate experiments the tissue surface was treated with Nizoral within a triangular former, and subsequently blotted onto a matrix-coated membrane. Sample membranes were then mounted into the recess of specialised MALDI targets with adhesive tape. All samples were analysed by MALDI-TOFMS using an Applied Biosystem 'Q-star Pulsar i' hybrid Q-TOF mass spectrometer fitted with an orthagonal MALDI ion source and imaging software. Detection of the protonated molecule was readily achievable by this technique. Treatment of the tissue within a template gave rise to images depicting the expected distribution of the drug, demonstrating that this technique is capable of producing spatially useful data. Ion images demonstrating the permeation of the applied compound into the skin were achieved by imaging a cross-sectional imprint of treated tissue. A calibration graph for the determination of ketoconazole was prepared using the sodium adduct of the matrix ion as an internal standard. This enabled construction of a quantitative profile of drug in skin. Conventional haematoxylin and eosin staining and microscopy methods were employed to obtain a histological image of the porcine epidermal tissue. Superimposing the mass spectrometric and histological images appeared to indicate drug permeation into the dermal tissue layer.

Comment: A simple, low-cost, air-spray method for improved sample preparation for matrix-assisted laser desorption/ionisation mass spectrometry of derivatised poly(ethylene glycol)

A simple, low-cost, air-spray technique has been evaluated for the preparation of matrix-assisted laser desorption/ionisation (MALDI) sample slides. Hydroxyl end groups of poly(ethylene glycol) Mn = 600 were functionalised by esterification using acetyl and butyryl chlorides. Air-spray deposition gave excellent shot-to-shot and spot-to-spot reproducibility; the observed compositions by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) being in agreement with those obtained from 1 H NMR. Compressed air-spray is an excellent, inexpensive, sample preparation procedure for simple routine MALDI-TOF MS which increases the reproducibility of this increasingly important technique for synthetic polymer analysis.