Electrostatic capillary collector for in-situ spectroscopic analysis of aerosols

Identification of particulate matter is important in assessing an individual’s exposure to potentially harmful particles, such as aeroallergens, toxins, and emissions from combustion sources, which can contribute to cardio-pulmonary diseases. Efficient collection of aerosols is essential for aerosol exposure studies such as analysis of chemical and biological components. We present the design and evaluation of a capillary collector that collects PM_2.5 onto the outer surface of a capillary for in-situ spectroscopic analysis. The capillary collector uses a needle-to-ring corona generator to charge particles; the electric field between a cylinder and a wire inserted into the bore of a capillary is used to collect the charged particles. Corona and repelling voltages are optimized for maximum collection of ambient PM_2.5 particles and fluorescent polystyrene latex microspheres in the PM_2.5 size range, on the capillary. The capillary collection efficiency of ambient PM_2.5 at 3 slpm operating flow rate and optimal operating voltages is 63%. Fluorescence spectroscopy is used to quantify the collection of polystyrene latex microspheres. The fluorescence-based capillary collection efficiency is in close agreement with the capillary collection efficiency of ambient PM_2.5. The collection and analysis methodology can be used to develop a compact, low-cost sensor for in-situ spectroscopic analysis of aerosols to determine their chemical composition for source apportionment.

Copyright © 2019 American Association for Aerosol Research     

Improving hydrophobicity of polyurethane by PTFE incorporation

A simple and facile method was established of incorporating polytetrafluoroethylene (PTFE) on to polyurethane (PU) to improve hydrophobicity of PU by incorporating low levels of fluorine at a molecular level. Nanocomposites were made by preparing PU in the presence of PTFE using seeded miniemulsion polymerization method. The resulting PTFE/PU nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, differential scanning calorimetric, and thermo gravimetric analysis (TGA). FTIR and TEM indicated changes observed in their structure, size and morphology. The water contact angle of PTFE/PU nanocomposite films increased with increasing amount of PTFE and more on blending with silica nanoparticles but a slight decrease in thermal stabilities of SiO₂/PTFE/PU nanocomposites were noticed. The hydrophobicity imparted by PTFE to PU surface was found to be at its best for 1 : 2 PTFE/PU latex film. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42779.     

Optical studies of ZnO/Ag nanojunctions

Ag/ZnO nano-hetero-junctions were synthesized by an electrochemical route. The optical absorption spectroscopy and photoluminescence studies reveal the reaction mechanism at the junction. Optical absorption spectra indicate presence of well-defined ZnO excitonic feature along with the Ag surface plasmon absorption feature at 400 nm. Moreover, ZnO green photoluminescence appears on junction formation with Ag. Detailed analysis of emission and excitation processes indicate that efficient charge transfer is taking place from ZnO to Ag. Ag is also responsible for creation of levels in the HOMO-LUMO gap of ZnO. This finding may be of relevance so far as p-type doping in ZnO is concerned.     

Optimized mobility management protocol for the IoT based WBAN with an enhanced security

Wireless Networks - Today, Wireless Sensor Network (WSN) is widely used for general purposes. With the propagation of the Internet of Things (IoT), security issues arise wherever the healthcare...     

Adsorptive removal of phthalate ester (Di-ethyl phthalate) from aqueous phase by activated carbon: a kinetic study

Adsorptive studies were carried out on Di-ethyl phthalate (DEP) removal from aqueous phase onto activated carbon. Batch sorption studies were performed and the results revealed that activated carbon demonstrated ability to adsorb DEP. Influence of varying experimental conditions such as DEP concentration, pH of aqueous solution, and dosage of adsorbent were investigated on the adsorption process. Sorption interaction of DEP onto activated carbon obeyed the pseudo second order rate equation. Experimental data showed good fit with both the Langmuir and Freundlich adsorption isotherm models. DEP sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be greater at acidic pH.     

CdO–CdS nanocomposites with enhanced photocatalytic activity for hydrogen generation from water

Nanocomposites of CdO–CdS have been prepared in ethylene glycol water mixture followed by heating at 300 °C. TEM and XRD studies confirmed the atomic scale mixing of CdO and CdS nanoparticles, leading to the formation of CdSO₃ phase at the interfacial region between CdO and CdS. Photocatalytic studies for hydrogen generation from water show an enhanced activity for CdO–CdS composites compared to individual components namely CdO or CdS nanoparticles. Based on optical absorption, surface area measurements, steady state and time resolved fluorescence studies, it is established that, enhanced absorption in the visible region, higher surface area and increase in lifetime of the charge carriers are responsible for the observed increase in hydrogen yield from water when composite sample was used as the photocatalyst compared to individual components. The composite sample when combined with Pt as co-catalyst exhibit a large increase in the photocatalytic activity.     

Passivation of n‐type emitter and p‐type base in solar cells via oxygen terminated silicon nanoparticles

Various measurements and experiments are performed to establish the mechanism of passivation on emitter and base of conventionally manufactured solar cell with p‐type base. The surface coatings on the emitter are removed. The bare surface is then coated with silicon (Si) nanoparticles (NPs) with oxygen termination. It shows an increase in the cell efficiency up to 14% over bare surface of solar cell. The NPs show enhancement in light scattering from the surface, but shows an increase in the recombination lifetime indicating an improved passivation. When back contact is partially removed, the coating on bare back side ( p‐type) of the solar cell also improves the cell efficiency. This is also attributable to the increased recombination lifetime from the measurements. Same NPs are seen to degrade the surface of n and p‐type Si wafers. This apparently contradictory behaviour is explained by studying and comparing the emitter (n‐type) surface of the solar cell with that of n‐type Si wafer and the back surface ( p‐type) with that of p‐type Si wafer. The emitter surface is distinctly different from the n‐type wafer because of the shallow p–n junction causing the surface depletion. Back surface has aluminium (Al) metal trace, which plays an important role in forming complexes with the oxygen‐terminated Si NPs (Si–O NPs). With these studies, it is observed that increase in the efficiency can potentially reduce the thermal budget in solar cell preparation. Copyright © 2013 John Wiley & Sons, Ltd.     

Interpenetrating photopolymers for intraocular lens application

Interpenetrating photopolymer network materials suitable for intraocular lens application are presented. A rapidly curable, transparent, hydrophobic material with appropriate optical and thermomechanical properties has been prepared from Benzyl acrylate and Benzyl methacrylate. To improve its biocompatibility and optimize surface—cell interactions, this material was modified with respect to its hydrophobicity. Materials which are more hydrophobic, and more hydrophilic, than the base resin were prepared by copolymerization with either a fluoroacrylate or a PEG acrylate respectively. All materials were characterized for their optical and thermomechanical properties. Their in‐vitro cytotoxicity and interaction with mouse fibroblast cells were also studied. It was shown that all materials of the study were biocompatible and more hydrophilic materials resisted cell attachment and may be more suitable for IOL application than their more hydrophobic counter parts of the study. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44496.     

Preparation and characterization of ceria nanoparticles supported on poly(4‐vinyl pyridine‐co‐divinyl benzene)

Formation of ceria nanoparticles in 2% divinyl benzene (dvb) crosslinked 4‐vinyl pyridine (4vp) polymer [poly(4vp‐co‐dvb)] microspheres was investigated. The polymer was prepared by free radical suspension polymerization method. Poly(4vp‐co‐dvb)/ceria nanocomposites were prepared by reacting CeCl₃·7H₂O and NaOH in the presence of poly(4vp‐co‐dvb) at room temperature in aqueous media. The mole ratio of the metal to polymer was varied from 2.5 to 10% with an increment of 2.5. The polymer and nanocomposities were characterized by various spectrochemical methods. The coordination of nitrogen atoms of the polymer with Ce(IV) of ceria (CeO₂) has been confirmed from X‐ray photoelectron spectroscopy (XPS). The method has yielded ceria nanoparticles in an average size of 15 nm according to transmission electron microscopy. Differential scanning calorimetry, thermogravimetric analysis, X‐ray diffractometry and XPS analysis with respect to mole percentage of ceria in the composite are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3439–3445, 2006