Inter range cell interference (IRCI)-free synthetic aperture radar (SAR) imaging algorithms experience antenna-based interference which severely degrades the SAR image. In this letter, we propose a ...low complexity interference mitigation technique based on array processing for IRCI-free SAR imaging algorithms. A low complexity array processing is proposed, by designing a linear array with a limited number of fully controllable elements. The complex weight of array elements is optimized for the desired array pattern with constraints on close-in sidelobe levels (SLL). The proposed methodology reduces the desired two-way SLL to 40.5 dB by using only 18 fully controllable elements out of 100 array elements. The state-of-the-art improved-gray wolf optimization (I-GWO) is used for optimization and is shown to be computationally more efficient than some well-known optimization algorithms. Finally, simulated SAR images validate the effectiveness of the proposed technique.
In this paper, a circular economy approach with the adsorption and desorption of heavy metal (HM) ions—i.e., lead (Pb2+), chromium (CrT), and mercury (Hg2+)—from aqueous solutions was studied. ...Specific and selective binding of HM ions was performed on stabilized and amino-functionalized iron oxide magnetic nanoparticles (γ-Fe2O3@NH2 NPs) from an aqueous solution at pH 4 and 7. For this purpose, γ-Fe2O3@NH2 NPs were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), specific surface area (BET), transmission electron microscopy (TEM), EDXS, and zeta potential measurements (ζ). The effects of different adsorbent amounts (mads = 20/45/90 mg) and the type of anions (NO3−, Cl−, SO42−) on adsorption efficiency were also tested. The desorption was performed with 0.1 M HNO3. The results showed improvement of adsorption efficiency for CrT, Pb2+, and Hg2+ ions at pH 7 by 45 mg of g-Fe2O3@NH2 NPs, and the sequence was as follows: CrT > Hg2+ > Pb2+, with adsorption capacities of 90.4 mg/g, 85.6 mg/g, and 83.6 mg/g, respectively. The desorption results showed the possibility for the reuse of γ-Fe2O3@NH2 NPs with HNO3, as the desorption efficiency was 100% for Hg2+ ions, 96.7% for CrT, and 91.3% for Pb2+.
NaREF4 nanocrystals of the lighter rare earth elements RE = La, Ce, Pr, Nd are more difficult to prepare than those of the heavier lanthanides because the materials are sensitive to decomposition. ...Here, we present a procedure for the synthesis of sub-10 nm particles of β-NaLaF4, β-NaCeF4, β-NaPrF4, and β-NaNdF4, as well as of α-NaCeF4, α-NaPrF4, and α-NaNdF4. These particles were used to study the decomposition reaction taking place in the standard oleic acid/octadecene solvent. Ostwald ripening of the β-phase particles in this solvent leads to the expected particle growth and broadening of the particle size distribution only in the case of RE = Ce, Pr, Nd, whereas particles of NaLaF4 decompose to LaF3. Ostwald ripening of the α-phase particles in oleic acid/octadecene yields two products: larger particles of the hexagonal β-phase with a very narrow size distribution and smaller particles of the rare earth trifluoride REF3. The yield of the nearly monodisperse β-NaREF4 particles decreases from Nd to Ce and becomes negligible for the latter. X-ray fluorescence analysis reveals that the decomposition into the REF3 phase is caused by a strong sodium deficiency of the cubic α-NaREF4 nanocrystals, which is observed even if these particles are prepared in the presence of a 6-fold excess of sodium ions. We show that larger particles of phase-pure β-NaCeF4, β-NaPrF4, and β-NaNdF4 can nevertheless be prepared by Ostwald ripening of the corresponding cubic α-NaREF4 particles, if the sodium deficiency of the latter is compensated for during their conversion to the β-phase.
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•Different morphologies of CuO NSs were synthesized by surfactant-assisted and surfactant-free hydrothermal synthesis method.•The influence of surfactants on properties of CuO NSs was ...analyzed.•Aniline blue and malachite green dye were degraded under direct sunlight.•Floral layers like CuO NSs enhances the photocatalytic activity and suppress the bacterial growth.•Floral layers like CuO NS can be used as an ideal catalyst for water purification.
In the present work, three different morphological CuO nanostructures (CuO NSs) were synthesized, and analyzed the impact of surfactants on the morphology, surface area, photocatalytic and antimicrobial activity. The crystalline size was estimated in the range of 14.2–44 nm. BET results indicate that the floral layer like CuO has mesopores structure and enhanced surface area. The photocatalytic activity of CuO nanostructures was studied by the degradation of Aniline blue and Malachite green in sunlight. Novel floral layer like CuO NS exhibited superior photocatalytic performance for both dyes. The stability and reliability of the CuO (SDS) NS was examined through recycling experiment. Additionally, the potent antimicrobial activity of synthesized CuO nanostructures was analyzed. It was found that a floral layer like CuO nanostructure shows more zone of inhibition (15–20 nm) against human pathogens. Thus, the floral layer like CuO nanostructure can be used as an ideal material for water treatment.
Ultrafast spectroscopy reveals the effects of confinement on the excited-state photoisomerization dynamics for a series of alkyl-substituted trans-stilbenes encapsulated in the hydrophobic cavity of ...an aqueous supramolecular organic host–guest complex. Compared with the solvated compounds, encapsulated trans-stilbenes have broader excited-state absorption spectra, excited-state lifetimes that are 3–4 times longer, and photoisomerization quantum yields that are 1.7–6.5 times lower in the restricted environment. The organic capsule disrupts the equilibrium structure and restricts torsional rotation around the central CC double bond in the excited state, which is an important motion for the relaxation of trans-stilbene from S1 to S0. The location and identity of alkyl substituents play a significant role in determining the excited-state dynamics and photoisomerization quantum yields by tuning the relative crowding inside the capsule. The results are discussed in terms of distortions of the ground- and excited-state potential energy surfaces, including the topology of the S1–S0 conical intersection.
Employing hydrothermal technique, undoped and nickel doped cerium oxide nanoparticles (Ni doped CeO2 NPs) are synthesized with different concentration of dopant (5 M%, 10 M% and 15 M%). Prepared ...samples are subjected to Powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), High resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV–vis), Photoluminescence spectroscopy (PL), Vibrational sample magnetometry (VSM), Dielectric and electrical conductivity studies. Formation of CeO2 NPs and Ni doped CeO2 NPs is confirmed by PXRD and EDX. The crystallite size of the samples, determined from powder XRD using Williamson-Hall (W–H) plot, diminishes with increased Ni doping. The lattice parameter variation indicates an initial lattice contraction when the doping is less and a lattice expansion with enhanced Ni doping. These variations in crystallite size and lattice parameter could be due to the replacement of Ce ions by Ni ions in the CeO2 lattice. SEM and HRTEM images show that the morphology of the NPs formed is nearly spherical. The UV–vis spectroscopic studies indicated that bandgap energy of Ni doped CeO2 NPs widens as the Ni dopant concentration is increased. Increase of oxygen vacancy (VO) with increase in Ni concentration is designated by Raman spectra. The PL studies show that the nanoparticles of CeO2 and Ni doped CeO2 exhibit luminescence in the violet-blue-green wavelengths region (400 nm–500 nm). The decrease in emission intensity with increase of Ni concentration is indicative to increase of oxygen vacancies with increase in Ni content which act as non-radiative centers. VSM studies show that all the samples exhibit paramagnetism. The saturation magnetization and the retentivity of the samples increase as the Ni dopant concentration increases. All the samples display frequency dependent dielectric properties. With increase in the concentration of Ni dopant and frequency, a reduction in the values of dielectric constant and dielectric loss and an improvement in the electrical conductivity were observed for all the samples.
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•(Å) could be due to the smaller ionic radius of Ni2+ (0.70 Å) than Ce4+ (0.97 Å).•Ce, Ni & O are present in desired amounts and no other impurities are detected.•TEM suggest that the Ni2+ dopant perhaps inhibit the growth of the cubic phase.•Between cerium cations & oxygen anions is expected to produce anti-ferromagnetic.•Grain boundaries hinder the mobility of electrons between ions.
Urinary exosomes have received considerable attention as a potential biomarker source for the diagnosis of renal diseases. Notwithstanding, their use in protein biomarker research is hampered by the ...lack of efficient methods for vesicle isolation, lysis, and protein quantification. Here we report an improved ultracentrifugation-based method that facilitates the solubilization and removal of major impurities associated with urinary exosomes. A double-cushion sucrose/D2O centrifugation step was used after a two-step differential centrifugation to separate exosomes from the heavier vesicles. After the removal of uromodulin, 378 and 79 unique proteins were identified, respectively, in low- and high-density fractions. Comparison of our data with two previously published data sets helped to define proteins commonly found in urinary exosomes. Lysis, protein extraction, and in-solution digestion of exosomes were then optimized for MudPIT application. More than a hundred exosomal proteins were quantified by four-plex iTRAQ analysis of single and pooled samples from two different age groups. For healthy men, six proteins (TSN1, PODXL, IDHC, PPAP, ACBP, and ANXA5) showed significant expression differences between exosome pools of those aged 25–50 and 50–70 years old. Thus, exosomes isolated by our method provide the basis for the development of robust quantitative methods for protein biomarker research.
Aim: The aim of this study was to screen blood donors in a tertiary hospital in Kerala for dengue during the period of peak dengue transmission. Materials and Methods: One hundred and seventy-eight ...continuous serum samples obtained from asymptomatic blood donors during the monsoon season were subjected to ELISA for Dengue NS1 antigen and dengue immunoglobulin M (IgM) antibodies. Results: Dengue IgM antibodies were positive in 20 (11.23%) donors and NS1 antigen was positive in 1 (0.56%) donor. The presence of these markers in asymptomatic blood donors showed that they may have had active or subclinical dengue infection at the time of donation or in the recent past. The presence of NS1 in particular raises the possibility that the donor may have been viremic at the time of donation. Conclusion: The findings of this study suggest the risk of transfusion transmission of dengue during the monsoon in Kerala and strengthen the case for dengue screening among blood donors during this period of high incidence.
Excited anthracene is well-known to photodimerize and not to exhibit excimer emission in isotropic organic solvents. Anthracene (AN) forms two types of supramolecular host–guest complexes (2:1 and ...2:2, H:G) with the synthetic host octa acid in aqueous medium. Excitation of the 2:2 complex results in intense excimer emission, as reported previously, while the 2:1 complex, as expected, yields only monomer emission. This study includes confirming of host–guest complexation by NMR, probing the host–guest structure by molecular dynamics simulation, following the dynamics AN molecules in the excited state by ultrafast time-resolved experiments, and mapping of the excited surface through quantum chemical calculations (QM/MM-TDDFT method). Importantly, time-resolved emission experiments revealed the excimer emission maximum to be time dependent. This observation is unique and is not in line with the textbook examples of time-independent monomer–excimer emission maxima of aromatics in solution. The presence of at least one intermediate between the monomer and the excimer is inferred from time-resolved area normalized emission spectra. Potential energy curves calculated for the ground and excited states of two adjacent anthracene molecules via the QM/MM-TDDFT method support the model proposed on the basis of time-resolved experiments. The results presented here on the excited-state behavior of a well-investigated aromatic molecule, namely the parent anthracene, establish that the behavior of a molecule drastically changes under confinement. The results presented here have implications on the behavior of molecules in biological systems.
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