Combination Of Electrospraying Research Articles

Photoresponsive Superhydrophobic Membrane Crosslinked by Bipedal Pillararenes with Patterned Wettability

AbstractThe facile fabrication of superhydrophobic membrane with patterned and controllable wettability is crucial to the exploitation of precise control of water flow path. Here, an azobenzene‐bridged bipedal pillararenes‐crosslinked polypseudorotaxane is used to fabricate a superhydrophobic membrane via the combination of electrospraying and breath figure approaches. Regulation of the relative humidity during electrospraying process and the trans‐cis isomerization of azobenzene provide the capability to control the water adhesion force of membrane. These rules are applied to engineer the wettability of membrane into various patterns via re‐electrospraying or light irradiation with patterned photomask. These efforts demonstrate the potential of polypseudorotaxanes for applications in smart membrane with patterned wettability.

How Does Azo Bond Cleave in the Gas Phase? Computational and Experimental Study on the Fragmentation Mechanism of Protonated Sudan I

AbstractAs a cheap but harmful additive in food industry, 1‐phenylazo‐2‐naphthol (Sudan I) has attracted lots of attentions, which mainly focused on the determinations using the HPLC‐ESI‐MS/MS techniques. However, the fragmentation mechanisms are generally scarce. In this paper, the fragmentation pathways of protonated Sudan I in gas‐phase were investigated by a combination of electrospray ionization‐tandem mass spectrometry and density functional theory (DFT) calculations. Initially, the cleavage of azo bond is triggered by ionizing proton migration from the oxygen atom of O‐protonated Sudan I to adjacent N atom through a six‐member ring transition state, leading to a single ion‐neutral complex (INC‐s). Subsequently, the direct decomposition of INC‐s gives the naphtol nitrene ion at m/z 156. Meanwhile, INC‐s may occur an intermolecular single electron transfer (SET) reaction via the crossing points (INC‐mecp), affording the triple ion‐neutral complex (INC‐t) consisting of naphtol nitrene radical and aniline radical ion. Finally, followed by the decomposition of INC‐t, the aniline radical ion at m/z 156 is formed. Further studies on Electrostatic potential map, Natural population analysis (NPA) and frontier molecular orbitals (FMOs) during the proposed mechanism are also found to be in good agreement with experimental observations. Taken together, our results presented here not only provide mechanistic information for better understanding the Sudan I, but also give insights into other related harmful additives in food industry.

Highly adsorptive graphene aerogel microspheres with center-diverging microchannel structures

Novel graphene oxide aerogel microspheres (GOAMs) with well-defined “center-diverging microchannel” structures are obtained by a novel approach, i.e. a combination of electrospraying and freeze-casting. A formation mechanism, i.e. radial-directional freezing–thawing, was proposed. The reduced GOAMs exhibit excellent adsorption ability for various organic liquids and oils due to their highly hierarchical hydrophobic structure and a random packing effect.

Study of electrospray assisted electrophoretic deposition of carbon nanotubes on insulator substrates

In recent years, electrophoretic deposition (EPD) has been adopted as a cost-effective and reliable single-step solution-based room temperature coating method for carbon nanotubes (CNTs), predominantly on conducting surfaces. Contrary to this general pre-requisite of conductive target substrates, in this work we have explored a fabrication strategy for the scalable deposition of CNTs on insulating glass surfaces by the sequential combination of electrospraying and the EPD technique. This combined process flow has been referred to as “electrospray-assisted EPD”, where an initial CNT coating on glass substrates is obtained by electrospraying which, in turn, further assists CNT film growth by EPD. The successful integration of the electrospray technique in the EPD process flow also eliminates the need for surface functionalization of the insulator substrates prior to the deposition step. Electrospray-assisted EPD has resulted in the successful fabrication of uniform, homogenous, and thick CNT deposits (∼4.5 - 5 μm) with precise thickness control. A detailed investigation of the effect of the initial electrosprayed coating on the final CNT film growth and thickness is also presented in this report. This research endeavor presents a significant opportunity for the integration of this deposition model into a wider platform of materials research and technology, chemical sensing, and applications based upon printable and flexible electronics.

Dual drug release nanocomposites prepared using a combination of electrospraying and electrospinning

In this paper we demonstrate for the first time that structural nanocomposites providing dual drug release can be generated using a combination of electrospraying and electrospinning. Ketoprofen (KET) was used as a model drug, and polyvinylpyrrolidone (PVP) and Eudragit® L100-55 (EL100) respectively taken as the sheath and core matrices to prepare the nanofibers. Scanning and transmission electron microscope observations demonstrated that the nanofibers had smooth surfaces and cross-sections, and distinct core–sheath nanostructures. They also had relatively uniform diameters of 0.64 ± 0.21 μm. Differential scanning calorimetry and X-ray diffraction results indicated that the nanofibers contained KET homogeneously distributed in both the sheath and core parts of the fibers. IR spectra indicated that this molecular dispersion was likely to be a result of hydrogen bonding between the components. In vitro dissolution tests showed that the core–sheath fibers provided dual drug release profiles with an immediate release of 35.1% in acidic solutions and sustained release of 62.2% in a pH 6.8 phosphate buffer. The strategy developed here significantly expands the applications of electrohydrodynamic atomization processes in producing novel structural nanocomposites for complex and time-programmed drug release profiles.

Wastewater Decontamination from Microorganisms by Electrospraying Corona Discharge

A novel water treatment technique, based on a combination of electrospraying and pulsed corona discharge, has been used for bio-decontamination of wastewater. The electrospraying process has been found to increase the surface area of the treated wastewater, and hence increases the efficiency of the corona treatment process. The phase diagram of the discharge, which characterizes the discharge regimes, has been identified experimentally. The survival ratio of the microorganisms has been investigated experimentally as a function of the applied voltage and the numbers of treatment runs using air and oxygen as working gases. Microorganism surface has been examined using scanning electron microscope (SEM), which enabled in understanding the decontamination mechanisms of the treated microorganism. A complete decontamination has been achieved after only one run for an applied voltage higher than 16 kV when the discharge system was operated in oxygen gas. Optical emission spectrum of the electrosprayed water confirmed the existence of OH-radicals responsible for decontamination process.

Synthesis and characterization of TiO2 powders by electrospray pyrolysis method

Electrospray pyrolysis, i.e. combination of electrospray and in-flight thermal treatment, has attracted much attention as a preparation method of functional ceramic particles. In this paper, we report the processing detail of spherical TiO2 nano- and microparticles by the electrospray pyrolysis method as well as their photocatalytic activity for hydrogen evolution. Titanium(IV) bis(ammonium lactato)dihydroxide aqueous solutions (TALH aq., 0.2–20wt%) were injected into a capillary nozzle by a syringe pump (0.15–0.59mL/min), and were electrosprayed by using DC 4kV voltage, followed by the pyrolysis at 300–500°C. Spherical TiO2 nano- and microparticles were successfully obtained. Effects of precursor-liquid concentration, liquid flow-rate, and pyrolysis temperature on the particle size, microstructure and functions were discussed.

Chitosan fibrous 3D networks prepared by freeze drying

Nonwoven fabrics and structured particles prepared by electrohydrodynamic jetting have been attracting increasing attention in various research areas. Chitosan has been known as a poorly spinnable polymer, often electrospun using a mixed solution of polyethylene glycol. Herein, we report that a combination of electrospraying and subsequent freeze drying can produce chitosan fibrous 3D network structures from low concentration chitosan solutions, well below fiber forming concentrations. Nanoparticle suspensions of chitosan were first fabricated by a controlled electrospraying process and then freeze drying assembled the nanoparticles into fibrous networks. The formation of a columnar ice phase and subsequent drying produced chitosan fibrous structures of a few microns in diameter. The X-ray diffraction results and the surface morphologies of the fibers indicate a unique fiber formation mechanism of biaxial compression. This technique can prepare nonwoven fabrics from nanoparticles, which lead to novel opportunities in applications including tissue engineering, cell or drug delivery, and membranes.

Gas-phase study of new organozinc reagents by IRMPD-spectroscopy, computational modelling and tandem-MS

An extensive set of organozinc iodides, useful for Negishi-type cross-coupling reactions, are investigated as respective cations after formal loss of iodide in the gas phase. Firstly, two new alkylzinc compounds derived from Tyrosine (Tyr) and Tryptophan (Trp) are closely examined. Secondly, the influence of specific protecting groups on the subtle balance between intra- and intermolecular coordination of zinc in these reagents is probed through trifluoroacetyl (TFA)-derivatized alkylzinc compounds. Finally, the influence of the strongly coordinating bidentate ligand N,N,N',N'-tetramethylethylenediamine (TMEDA) on the structure of alkylzinc cations is further explored in order to better understand the stability of the respective complexes towards water. A combination of electrospray (ESI)-MS/MS, accurate ion mass measurements, infrared multiple-photon dissociation (IRMPD) spectroscopy and computational modelling allowed the full characterisation of all dimethylformamide (DMF)-solvated and TMEDA-coordinated alkylzinc cations in the gas phase. The calculations indicate that the zinc cation in gas-phase alkylzinc-DMF or TMEDA-complex ions preferentially adopts a tetrahedral coordination sphere with four ligands. Additionally, conformers with only three binding partners bound to zinc but with effectively combined hydrogen-bond interactions are also found. Collision induced dissociation (CID) patterns demonstrate that the zinc-DMF interaction in tetrahedral four-coordinate mono-DMF-zinc complex ions as well as the interaction between TMEDA and zinc in the corresponding complex ions is even stronger than typical covalent bonds. In most cases, all major features of the IRMPD spectra are consistent with only a single major isomer, allowing secured identification and assignment.

Structure Elucidation of Dimethylformamide-Solvated Alkylzinc Cations in the Gas Phase

Organozinc iodides, useful for the synthesis of nonproteinogenic amino acids, are investigated in the gas phase by a combination of electrospray (ESI)-MS/MS, accurate ion mass measurements, and infrared multiphoton dissociation (IRMPD) spectroscopy employing a free electron laser. ESI allowed the full characterization of a set of dimethylformamide (DMF)-solvated alkylzinc cations formed by formal loss of I(-) in the gas phase. Gas phase ion structures of the organozinc cations were identified and optimized by computations at the B3LYP/6-311G** level of theory. The calculations indicate that the zinc cation in gas phase alkylzinc-DMF species preferentially adopts a tetrahedral coordination sphere with four ligands, namely the alkyl group, any internal coordinating group, and DMF (the number of which depends on the number of internal coordinating groups present). Besides the sequential loss of coordinated DMF, collision-induced dissociation (CID) patterns demonstrate that the zinc-DMF interaction in tetrahedral four-coordinate mono-DMF-zinc complex ions can be even stronger than covalent bonds. The IRMPD spectra of the alkylzinc-DMF species examined show a rich pattern of indicative bands in the range of 1000-1800 cm(-1). All major features of the recorded IRMPD spectra are consistent with the computed IR spectra of the respective gas phase ion structures predicted by theory, allowing identification and assignment.

The combination of electrospray and flow focusing

An ultra-fine liquid atomization procedure combining the advantages of electrospray and flow focusing is presented. Both techniques are known to produce strikingly small and steady liquid micro-jets issuing from menisci held by capillary forces. Such menisci take the form of a cusp-like drop attached to the feeding tube (flow focusing: FF) or a Taylor cone (electrospray: ES). The issuing micro-jets are forced or ‘sucked’ from the parent meniscus either by pressure or electrohydrodynamic forces. Subsequent capillary breakup of the jet leads to fine sprays of remarkable quality. Here we describe the joint effect of pressurization and electrification in a flow focusing device, and the subsequent coupling of both ES and FF phenomena. For any given liquid and flow rate, the combined procedure gives rise to significantly smaller droplet sizes than observed in any of the source techniques. The co-flowing gas stream removes space charges; in addition, the perforated plate facing the feed tube provides an electric barrier, shielding the jet-meniscus or ‘production’ area from the spray or ‘product’ area. As a result, space charges and electrified droplets are removed from the production area, thus avoiding the ambient electric saturation which becomes a limiting factor in ES-spraying: a significantly enhanced spraying stability ensues, with a much wider operation range than FF or ES. Other unexpected outcomes from the combination are also shown. A theoretical model is developed to predict the emitted droplet size: a first integral of the momentum equation yielding a generalized Bernoulli equation, and an explicit approximation for the jet diameter and droplet size, accurate within a broad parametrical band.

Mass spectrometric analysis of the structure of γ II bovine lens crystallin

The amino acid sequence of bovine γ II -crystallin has been verified by a combination of electrospray and fast atom bombardment mass spectrometry. The molecular weight of γ II , isolated by gel filtration and ion exchange chromatography, was determined to be 20967 ± 3 by electrospray mass spectrometry. Another aliquot of γ II was completely digested by trypsin in a medium of 20% CH 3CN and 0·1 m Tris, pH 8·2. The tryptic peptides were separated by reversed phase HPLC and identified by their molecular weights, as determined by fast atom bombardment mass spectrometry (FABMS). The identification of each peptide was confirmed by digesting the peptide further to give new peptides whose molecular weights were also determined by FABMS and related to the proposed amino acid sequences. The data from both types of mass spectrometric analyses were consistent with the sequence previously proposed by Hay et al. ( J. Biol. Chem. 1987, 146, 332–338), including threonine at position 119. The FAB mass spectrum of one HPLC fraction suggested that disulfide bonding between Cys 18 and Cys 22 was present in at least half the protein preparation. Whether the Cys 18 Cys 22 disulfide bond was present in native γ II or was produced during isolation or enzymic digestion could not be determined from these studies. Samples that had been stored for several weeks showed that several of the cysteines had become disulfide bonded. These studies illustrate the power of mass spectrometric techniques to accurately confirm the primary structure of proteins and to identify post-translational modifications.