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•Water soluble carbon quantum dots have been prepared through hydrothermal route.•A novel fluorescent probe for the detection of Fe3+ ion is established.•The established sensing ...platform exhibited limit of detection of 0.2 μM.•The probe was successfully employed to monitor Fe3+ ion in real water samples.
In this study, we have reported an economical, easy, greener and non-toxic synthesis route of water soluble carbon quantum dots (CQDs) through hydrothermal treatment using gelatin as precursor. Under the UV lamp of wavelength 365 nm, the as-prepared CQDs exhibit strong blue fluorescence along with CIE coordinate index of (0.17, 0.14) and possess a quantum yield of 22.7% with rhodamine B as standard. The morphology of as-synthesized CQDs as investigated by TEM measurement confirmed their spherical shape and also revealed that their sizes varied in the scale of 0.5–5 nm. Furthermore, the CQDs showed excitation dependent fluorescence emission behaviour in range of 280 nm to 420 nm as a result of quantum confinement effect. Apart from this, in CQDs solution, the addition of Fe3+ ion lead to fluorescence quenching effect. These results revealed that the as-synthesized CQDs have a sensitive response towards the Fe3+ ion. The calculated limit of detection (LOD) is 0.2 μM with correlation coefficient R2 = 0.996 in the concentration range 0 to 50 μM. More remarkably, the application of CQDs for monitoring the trace level of Fe3+ ion in tap water yielded acceptable recoveries (103.33%-105%). Therefore, this work provides a novel additional fluorescent probe for the detection of Fe3+ ion in real world.
This manuscript is based on an investigation of bouncing cosmology in a 4D Einstein Gauss-Bonnet gravity. Various bouncing models such as symmetric bounce, matter bounce, super bounce, and ...oscillatory bounce have been examined. Expressions for energy density, pressure, equation of state parameter have been derived in the most general manner and then reduced to 4D Einstein Gauss-Bonnet gravity for isotropic, homogenous, FLRW cosmos. Physical interpretation of Hubble and deceleration parameters has also been discussed and plotted for each model from non-vanishing scale factors. Non-singular bouncing models indulge in accelerating late-time cosmic acceleration phenomenon. It has been analysed that the Gauss-Bonnet coupling parameter has a lesser contribution to the dynamics of modified gravity while the bouncing parameter has noticeable effects. We have examined various energy conditions and witnessed the violation of strong and null energy conditions in bouncing models. Analytical expressions for jerk and snap parameters have also been calculated in terms of cosmic time and redshift. We have explored bouncing models through specific cosmographic tests to check their validity. Also, through stability analysis, matter bounce becomes the most stable model by increasing the value of the bouncing parameter. To find best-fit values, bouncing models have been constrained with Hubble data set and
Λ
CDM. We have calculated the values of parameters by applying the least-square fitting method. To make this analysis quantified, we have employed reduced chi-squared method on
H
(
z
) data sets for each model.
In recent years, research attention on smart grid comprising distributed power generators has increased. To produce electricity in the smart grid, many micro grids (MGs) may exploit various renewable ...energy resources. Because the production capacity of renewable resources cannot be controlled, the MGs often require the power plants to provide power for them. However, the power loss between each MG and the power plant is larger than that among the MGs. To alleviate this power loss, we propose a game theoretic coalition formulation strategy for the MGs dubbed GT-CFS. Our proposed GT-CFS allows the MGs (belonging to the same macro station (MS)) to autonomously cooperate and self-organize into a partition composed of disjoint MG coalitions. Also, GT-CFS enables the MGs, in a distributed manner, to decide whether they will remain in the coalitions or not upon environmental changes, e.g., the variation of the power demand of the MGs. Within every coalition, MGs coordinate the power transfer among themselves as well as with the MS, in a fashion to optimize a utility function, which captures the total losses over the power distribution lines. MGs in the same coalition will distribute the extra profits (i.e., payoff) produced from forming coalitions by their "Shapley value." Through computer simulations, we demonstrate that the proposed GT-CFS reduces the average power loss per MG significantly in contrast with the conventional noncooperative approach.
This paper deals with the theoretical modeling of anisotropic compact stars in the framework of
f
(
T
) theory of gravity, where
T
is torsion scalar. To this end, we have used the exact solutions of ...Krori and Barua metric to a static spherically symmetric metric. The unknown constants involved in the Krori and Barua metric have been specified by using the masses and radii of compact stars 4
U
1820-30, Her X-1, SAX J 1808-3658. The physical properties of these stars have been analyzed in the framework of
f
(
T
) theory. In this setting, we have checked the anisotropic behavior, regularity conditions, stability and surface redshift of the compact stars.
This paper reports on the investigations regarding the possible formation of compact stars in
f
(
R
,
T
)
theory of gravity, where
R
is the Ricci scalar and
T
is the trace of the energy–momentum ...tensor. In this connection, we use the analytic solution of the Krori and Barua metric (Krori and Barua in J. Phys. A., Math. Gen. 8:508,
1975
) for a spherically symmetric anisotropic star in the context of
f
(
R
,
T
)
gravity. The masses and radii of compact star models, namely Model 1, Model 2, and Model 3, are employed to incorporate the unknown constants in the Krori and Barua metric. The physical features such as regularity at the center, the anisotropy measure, causality, and the well-behaved condition of the above-mentioned class of compact starts are analyzed. Moreover, we also discuss the energy conditions, stability, and surface redshift in
f
(
R
,
T
)
gravity.
The activity concentrations of natural radionuclides 226Ra, 232Th and 40K in soil samples collected from Sijua Dhanbad, India were measured by using a gamma-ray spectrometer with a NaI(Tl) detector. ...The average activity concentration of 226Ra, 232Th, and 40K was found as 60.3, 64.5 and 481.0 Bq. kg−1, respectively. Average radium equivalent activity, absorbed dose rate, outdoor dose, external hazard index and internal hazard index for the area under study is determined as 189.5 Bq. kg−1, 87.2 nGy h−1, 0.4, 0.5 and 0.6 mSv. y−1, respectively. The annual effective dose to the general public is found 0.4 mSv. y−1. This value lies well below the limit of 1 mSv. y−1. Measured values have found safe for the environment and public health of the study area.
Earth Sciences; Environmental science; Atmospheric science; Geochemistry; Geology; Geophysics; Nuclear physics; Physics methods; Natural Hazards; Nuclear Engineering
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•Discussion of recent progress in reversible assembly of Au NPs, to include challenges and solutions.•Importance of assembly/dissassembly of different materials especially noble ...nanoparticles.•Reversible assembly of Au NPs induced by light, pH, temperature, electrical and magnetic field.•Stimuli responsive ligands and polymers covering the surface of Au NPs for reversible assembly.•Factors influencing the possible attratcive and repulsive forces between the nanoparticles.
Noble metal nanoparticles are highly attractive, owing to their optical, physical, electrical and chemical properties. Specifically, ease of surface modification, exceptional plasmonic and optical properties of gold nanoparticles (Au NPs) have created increasing interest in the assembly process. Once assembly is achieved successfully, the disassembly of the Au NPs is considered to be an exciting challenge. There are different kinds of forces involved in the assembly and disassembly process of Au NPs with a great deal involving the chemistry of surfactants. These forces can be externally triggered to achieve reversible assembly and disassembly. Less effort has been devoted to collate the study and mechanism involved behind environmentally or chemically triggered reversible assembly of Au NPs. Hence, the emphasis of this review is to highlight a number of promising stimuli such as light, pH, temperature and magnetic fields that can cause the reversible assembly of Au NPs. In addition, the surfactants utilized for assembly and disassembly of Au NPs under external stimuli response are examined. Furthermore, this review gives an account of the mechanism and chemistry of reversible assembly of Au NPs, taking into account the latest published literature. Indeed, it covers many ligands, biomolecules and thiol-mediated surfactants that can be linked to the surface of Au NPs and can also respond to external stimuli, realizing reversible assembly. The emerging challenges and an outlook on future developments in this research area are also discussed. The ultimate goal of this review is to encourage synthetic chemists to use ligand functionalized Au NPs (building blocks) for complex chemical systems as it will revolutionize the organic ligand synthetic processes that are responsive to different stimuli.
To support poliomyelitis eradication in Pakistan, environmental surveillance (ES) of wastewater has been expanded alongside surveillance for acute flaccid paralysis (AFP). ES is a relatively new ...method of surveillance, and the population sensitivity of detecting poliovirus within endemic settings requires estimation.
Data for wild serotype 1 poliovirus from AFP and ES from January 2011 to September 2015 from 14 districts in Pakistan were analysed using a multi-state model framework. This framework was used to estimate the sensitivity of poliovirus detection from each surveillance source and parameters such as the duration of infection within a community.
The location and timing of poliomyelitis cases showed spatial and temporal variability. The sensitivity of AFP surveillance to detect serotype 1 poliovirus infection in a district and its neighbours per month was on average 30.0% (95% CI 24.8-35.8) and increased with the incidence of poliomyelitis cases. The average population sensitivity of a single environmental sample was 59.4% (95% CI 55.4-63.0), with significant variation in site-specific estimates (median varied from 33.3-79.2%). The combined population sensitivity of environmental and AFP surveillance in a given month was on average 98.1% (95% CI 97.2-98.7), assuming four samples per month for each site.
ES can be a highly sensitive supplement to AFP surveillance in areas with converging sewage systems. As ES for poliovirus is expanded, it will be important to identify factors associated with variation in site sensitivity, leading to improved site selection and surveillance system performance.
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