•Nano zinc phosphate coating on mild steel was developed.•Nano zinc phosphate coatings on mild steel showed enhanced corrosion resistance.•The nano ZnO increases the number of nucleating sites for ...phosphating.•Faster attainment of steady state during nano zinc phosphating.
Nano crystalline zinc phosphate coatings were developed on mild steel surface using nano zinc oxide particles. The chemical composition and morphology of the coatings were analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The particles size of the nano zinc phosphate coating developed was also characterized by TEM analysis. Potentiodynamic polarization and electrochemical impedance studies were carried out in 3.5% NaCl solution. Significant variations in the coating weight, morphology and corrosion resistance were observed as nano ZnO concentrations were varied from 0.25 to 2g/L in the phosphating baths. The results showed that nano ZnO particles in the phosphating solution yielded phosphate coatings of higher coating weight, greater surface coverage and enhanced corrosion resistance than the normal zinc phosphate coatings (developed using normal ZnO particles in the phosphating baths). Better corrosion resistance was observed for coatings derived from phosphating bath containing 1.5g/L nano ZnO. The activation effect brought about by the nano ZnO reduces the amount of accelerator (NaNO2) required for phosphating.
Active phased array radars for the atmospheric research have various advantages such as full beam agility in 360°, improved signal-to-noise ratio and improved sensitivity. These radars have ...distributed transmit–receive modules feeding to the individual antenna system in the antenna array field. In order to control and monitor the field-located transmit–receive modules from centralized radar controller which will be located few hundred meters away from the field, control signals plays an important role in controlling the radar subsystems. Earlier generation radars used electrical cables to transfer such type of signals, where signal speed and bandwidth are limited. In addition, the electromagnetic interference also affects the transmit and receiving signals. To overcome these problems, a new technical approach has been developed over optical interface for active phased array radar. In this paper, we present the design and development of the optical control signal network for 53 MHz active phased array radar. The design details, component selection and the link budget calculations are explained in detail and the test results are provided.
In recent years, cerium oxide has been the most widely studied photocatalyst due to its unique properties. However, bare CeO
2
shows poor photocatalytic performance under visible-light irradiation ...because it absorbs only UV light that leads to fast recombination of photogenerated electron-hole pairs. Therefore, surface modification can be one of the effective strategies to improve the visible-light absorption and reduce the recombination rate of photogenerated charge carriers. Herein, a series of CeO
2
/polydopamine (CeO
2
@PDA) composites were successfully fabricated by the polymerization of dopamine on the surface of CeO
2
. Our results demonstrated that the surface modification of CeO
2
by a small amount of PDA could effectively inhibit the photocatalytic reaction; this not only promoted the photoelectron injection and reduced the charge recombination rate, but also controlled the overgrowth of Pt cocatalyst. As compared to bare CeO
2
, CeO
2
@PDA shows remarkable photocatalytic hydrogen production performance. This composite also presents good durability and stability for the photocatalytic hydrogen production reaction. Thus, this study provides a new insight into the preparation of CeO
2
composites with effective solar energy conversion.
In recent years, cerium oxide has been the most widely studied photocatalyst due to its unique properties.
The cobalt oxide (Co3O4) nanomaterials were prepared by coprecipitation synthesis technique by maintaining the pH of the mother solution at 7, 8, and 9. The prepared nanomaterials were subjected to ...structural and optical characterizations, and the results were examined. The optical absorption spectral studies reveal that the two absorption bands indicate ligand–metal coordination. The photoluminescence spectra contain emission peak at 488 and 745 nm due to size and shape of the synthesized materials. The magnetic nature of the samples was identified from the hysteresis loop traced by vibrating sample magnetometry (VSM). The Fourier transform infrared (FT-IR) spectrum of Co3O4 nanomaterials reveals two sharp bands absorbed in 584 and 666 cm-1. This ascribes to the Co-O and O-Co-O stretching, respectively. As the pH of the solution varied from 7 to 10, the SEM image authenticates the transformation of Co3O4 nanomaterials morphology from spherical to cubic to agglomerated shape. From the UV-Vis spectra, two absorption bands around 473 nm and 762 nm are observed for the materials prepared at pH 7 and 8. But at pH 9, these two peaks were shifted towards higher wavelengths 515 nm and 777 nm. The observed ferromagnetic nature of Co3O4 nanomaterials clearly show the role of surface spins and surface morphology on the magnetic properties of Co3O4 nanomaterials. The cyclic voltammetry (CV) curves show the rectangular type of voltammogram. This is an indication of good charge propagation with the electrodes. The Nyquist plots of Co3O4 nanomaterials have a semicircle in the high frequency region and a vertical line in the low frequency region. The results suggest that Co3O4 is found to be a promising material for the fabrication of light-emitting diodes, solar cells, and optoelectronic devices.
•Nano SiO2 incorporated nano zinc phosphate coating on mild steel was developed.•Coatings showed enhanced corrosion resistance.•The nano SiO2 is adsorbed on mild steel surface and become nucleation ...sites.•The nano SiO2 accelerates the phosphating process.
This paper reports the development of nano SiO2 incorporated nano zinc phosphate coatings on mild steel at low temperature for achieving better corrosion protection. A new formulation of phosphating bath at low temperature with nano SiO2 was attempted to explore the possibilities of development of nano zinc phosphate coatings on mild steel with improved corrosion resistance. The coatings developed were studied by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Electrochemical measurements. Significant variation in the coating weight, morphology and corrosion resistance was observed as nano SiO2 concentrations varied from 0.5–4g/L. The results showed that, the nano SiO2 in the phosphating solution changed the initial potential of the interface between mild steel substrate and phosphating solution and reduce the activation energy of the phosphating process, increase the nucleation sites and yielded zinc phosphate coatings of higher coating weight, greater surface coverage and enhanced corrosion resistance. Better corrosion resistance was observed for coatings derived from phosphating bath containing 1.5g/L nano SiO2. The new formulation reported in the present study was free from Ni or Mn salts and had very low concentration of sodium nitrite (0.4g/L) as accelerator.
A facile synthesis of sheets-on-sheet mesoporous Ni–Co-hydroxide/reduced graphene oxide (RGO) nanocomposites
via
the chemical decomposition of nickel cobalt hexacyanoferrate (NiCoHCF) complex is ...demonstrated. The chemical decomposition of NiCoHCF by NaOH resulted in the formation of Ni–Co-hydroxide directly on RGO that was confirmed by powder XRD analysis. The formation of Ni–Co-hydroxide nanosheets on RGO nanosheet was revealed using FE-SEM and HR-TEM analyses. The mesoporous nature of sheets-on-sheet Ni–Co-hydroxide/RGO nanocomposites was realized using BET surface area analysis and pore-size distribution. The electrochemical performance of Ni–Co-hydroxide/RGO nanocomposites with different weight ratios was evaluated using cyclic voltammetry, galvanostatic charge discharge measurements and electrochemical impedance spectroscopic analysis. The nanocomposite with a 1 : 1 ratio of Ni–Co-hydroxide and RGO exhibited a very high specific capacitance of 835 F g
−1
at 1 A g
−1
current density with an excellent capacity retention of 92% even after 5000 cycles. The magnetic properties of pristine Ni–Co-hydroxide and its nanocomposites with RGO were also investigated. The reported method is simple and scalable for growth of Ni–Co-hydroxide nanosheets over RGO nanosheets.
Newly acquired multi‐receiver capability of Advanced Indian MST radar has been utilized to implement the spaced antenna (SA) technique for profiling of winds and turbulence. Two experiments were ...conducted. In Experiment 1, in addition to the traditional Full Correlation Analysis (FCA), SA analysis is also performed on off‐vertical beam measurements (hereafter Oblique Spaced Antenna OSA) and the products are evaluated against those retrieved with Doppler Beam Swinging (DBS) and collocated GPS radiosonde. In Experiment 2, the dependence of height coverage on antenna aperture is examined. The synchronization and phase matching of receiving channels are found to be well within the designed values. The consensus averaged zonal and meridional wind velocities obtained by FCA and OSA compare very well with DBS and radiosonde measurements with correlation coefficients >0.85 and root mean square error (RMSE) < 2 ms−1. The mean value of antenna parameter, ah, extracted from correlation of different antenna pairs compare well with the theoretical estimate. The efficacy of ah in quality controlling the SA derived winds has been examined. Imposing ah condition has certainly removed several outliers and reduced the RMSE (relative to reference) considerably, but it also reduced useful data by 50%. The consensus averaging of winds is found to be more effective in removing outliers and reducing the RMSE. The wind variances estimated by DBS (after accounting the non‐turbulent contributions) and SA agree quite well with a correlation coefficient of 0.95. Utilization of a bigger array increased the height coverage from 10‐12 to 20 km.
Key Points
Indian MST radar has been upgraded into a fully active system with multi‐receiver capability, facilitating new processing techniques
Spaced antenna technique has been implemented not only using traditional vertical beam but also using off‐vertical beam measurements
The efficacy of the antenna parameter has been tested for its usage in quality controlling winds
Abstract
Background
Mosquito coil smoke, along with biomass fuel smoke, are sources of indoor air pollution. Biomass fuel smoke has been studied as a risk factor for poor respiratory outcomes. ...However, in an Indian context, few studies examine the effect of mosquito coil exposure on poor respiratory outcomes at the community level.
Objectives
To estimate the prevalence of the biomass fuel and mosquito coil use and to determine the association between the use of bio-mass fuel and mosquito coil and poor respiratory health.
Methods
A cross-sectional survey of 4662 individuals (above the age of 30 years) was conducted using a pre-tested questionnaire. Trained interviewers collected data on current and past use of biomass fuels and mosquito coils, usage practices and respiratory health. We computed proportions for exposure variables namely biomass fuel, mosquito coil use and other covariates. We conducted univariate analysis, followed by multivariate logistic regression.
Results
The prevalence of ever use of biomass fuels was high (wood: 97.9%; cow dung cake: 76.0% and crop residue: 54.4%). Current use of wood, cow dung cake and crop residue was prevalent among 75.7, 24.3 and 30.9% respondents, respectively. Almost 70% of respondents had ever used mosquito coils, whereas 54% were current users. Overall, 5.5% respondents had poor respiratory health either due to chronic bronchitis or asthma. In multivariate analysis, use of combination of all three biomass fuel types (adjusted odds ratio AOR 1.69, 95% confidence interval CI: 1.13–2.54) and use of mosquito coil more than or equal to 5 days per week (AOR 1.43, 95% CI: 1.04–1.99) were associated with poor respiratory health after adjusting for covariates age, gender, smoking, kitchen type and for each other.
Conclusions
Use of biomass fuels and mosquito coils was high in the study population and was associated with poor respiratory health. Therefore, mosquito coil smoke should also be considered an important source of indoor air pollution, similar to biomass fuel exposure. Community education about these sources of indoor air pollution and increased coverage of cleaner fuels and alternative mosquito control methods should be the way forward in the rural areas.
The monomer 1-(isopropylamino)-3-(1-naphthyloxy)-2-propanoacrylate (IANOPA) and monomer 1-(isopropylamino)-3-(1-naphthyloxy)-2-propanomethacrylate (IANOPMA) were synthesized by treating ...1-(isopropylamino)-3-(1-naphthyloxy)-2-propanol with acryloylchloride/methacryloyl chloride. The above esterification reactions were carried out in the presence of triethylamine. By employing the free radical polymerization method, the synthesized monomers were converted into polymers by using an initiator 2, 2′-azobisisobutyronitrile in the presence of nitrogen environment at 70±2°C. The monomers and polymers were characterized by various techniques such as FT-IR, UV, 1H NMR, and 13C NMR spectroscopic analyses. Further, differential scanning calorimetry (DSC) was used to estimate the glass transition temperature (Tg). Gel permeation chromatography (GPC) was used to estimate the molecular weight of the polymers. In addition, monomer and polymer surfaces’ morphology was analyzed using SEM analysis. As a primary application, the effectiveness of synthesized monomers and polymers was explored as antibacterial agents against gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) which were measured from their inhibitory zone diameters. Further, the synthesized polymers, poly-IANOPA and poly-IANOPMA, were utilized for the uptake ability study of heavy metal ions such as Zn2+, Cu2+, Ni2+, and Pb2+ present in water sources by equilibrium method.
Practical implementation of photocatalytic hydrogen production has been required for the invention of efficient visible light absorption and low cost photocatalyst materials. n-Type metal oxides can ...couple with p-type semiconductors to provide p–n heterojunctions. This is one of the possible strategies to simultaneously address the visible light absorption and charge separation issues. Hence, a noble metal free quaternary Cu2ZnSnS4 (CZTS) decorated CeO2 p–n heterojunction photocatalyst has been designed and confirmed by HRTEM, Raman and XPS analysis. The growth of CZTS on the surface of CeO2 has significantly enhanced the hydrogen production performance. The optimal amount of CZTS loaded on CeO2 achieved the highest hydrogen production efficiency of 2930 μmol h−1 g−1 under visible light illumination, which is 59 times higher than that for bare CeO2. It may be due to the fact that bare CeO2 contributes to UV light absorption. Moreover CeO2 coupled with CZTS has induced visible light absorption, separation and transmission of photoinduced charge carriers. However, the PL intensity of CZTS decorated CeO2 is significantly lower than that of the bare CeO2, which clearly demonstrates that the composite impedes the rapid recombination of electron–hole pairs.
