•ZnO nanoparticles were prepared by hydrothermal method for various solution pH.•The synthesized ZnO nanoparticles exhibit hexagonal wurtzite structure.•Morphology of ZnO nanoparticle was effectively ...influenced by solution pH.•94% of RhB dye degradation was observed for ZnO nanostructure prepared at pH 9.
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ZnO nanoparticles were prepared by hydrothermal method from the source materials of zinc chloride and ammonium hydroxide. Precursor solution pH was varied to 7, 9, 11 and 13 by the addition of ammonium solution and the solution was hydrothermally treated at 150°C for 3h. Further prepared samples were annealed at 400°C for 3h. X-ray diffraction technique was employed to study the structure and crystalline nature of synthesized nanoparticles. Diffuse Reflectance Spectroscopy studies revealed that optical band gap of ZnO is slightly varied due to the effect of size of the particle. Field emission scanning electron microscope images showed that the prepared ZnO nanoparticles acquired spindle like nanorods, hexagonal disk, porous nanorods and nanoflower structures due to the effect of pH of the precursor solution. Photocatlytic activity of the prepared ZnO nanoparticles was evaluated for Rhodamine B (RhB) dye which showed 94% of degradation and good stability for five cycles.
In the present study, we report morphology dependent photocatalytic activity of CuO/ZnO nanorods by simple chemical synthesis for the first time. The nanorod morphology was clearly evidenced by field ...emission scanning electron microscope (FESEM) and hig resolution transmission electron microscope (HRTEM) analysis and confirmed the particle size of 20 nm. The composition and oxidation states of the CuO/ZnO nanorods were confirmed by XPS analysis. The potential efficacy of CuO/ZnO nanorods was evaluated towards the photocatalytic degradation of congo red (CR) and rhodamine B (RhB) dye solution. Very interestingly, the CuO/ZnO nanorods showed significantly superior photocatalytic activity compared to CuO, ZnO, a mixture of nano CuO and nano ZnO. The complete degradation of dye solution was successfully achieved within a short span of time. The effects of the different operational parameters viz amount of photocatalyst loading, initial concentration and pH were evaluated and the optimum condition for the superior activity was discovered. The prevention of the electron-hole pair recombination was strongly evidenced by photoluminescence (PL) analysis. Importantly, active involvement of hydroxyl radical in the photocatalytic degradation mechanism was strongly supported by the trapping experiments using different scavengers and fluorescence analysis. The CuO/ZnO nanorods photocatalyst also showed excellent degradation activity against the mixed dye solutions (CR and RhB). The stability and reusability results were clearly indicated that the sustainability of the CuO/ZnO nanorods in the photocatalytic reaction.
Schematic representation of photocatalytic degradation of CR and RhB dye solutions in the presence of CuO/ZnO nanorods under visible light irradiation. Display omitted
•Hierarchically structured CuO/ZnO nanorods were synthesized by simple precipitation method.•The photodegradation of dyes were performed against congo red and rhodamine b dye solution.•Favorable conditions for the degradation were optimized.•Main reactive oxidative species were found out by trapping experiment.
Despite the beneficial aspect of aquatic food's consumption, bioaccumulation of toxic metals in fish can enhance the health risk for the consumers. Heavy metals were measured from editable tissues of ...some commercial fish species like Latis calcarifer, Silonia silondia, Clupisoma garua, Planiliza subviridis, Otolithoides pama, Tenulosa ilisa, Rhinomugil corsula, and Aila coila in the Meghna river estuary in Noakhali district. Heavy metals such as As, Pb, Cd, Cu, and Cr were detected by ICP-MS, which were significantly different (p ≤ 0.01), and the hierarchy of all mean concentrations were: Cu (5.14 mg/kg) > Pb (3.79 mg/kg) > As (1.08 mg/kg) > Cr (0.78 mg/kg) > Cd (0.12 mg/kg). The mean concentration of Cu (6.62 mg/kg) imparted to the maximum level in L. calcarifer, which slightly exceeded the Bangladesh food safety guideline. The mean BAFs of the contaminants were found as: Pb (1042.29) > Cr (1036.47) > As (934.84) > Cd (832.77) > Cu (772). Further, L. calcarifer, S. silondia, C. garua, and P. subviridis showed the bioaccumulative status. To assess the health risk effects, estimated daily intake (EDI), target hazard quotient (THQ) and carcinogenic risk (CR) were conducted. THQs for both adult and children consumers were <1, indicating that, consumers would not experience the non-carcinogenic health effects. Although children were more susceptible than adults, CR for all the consumers was found in the acceptable range (10−6 to 10−4).
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•In most cases, the concentration level of metals in the fish species were lower than some approved guidelines.•Mostly, fish species were bioaccumulative in the Meghna river estuary.•Calculated THQ, HI, and CR were in acceptable range.•Children consumer were higher susceptible than adults.
Additive manufacturing of aluminum alloys is largely dominated by a near-eutectic Al-Si compositions, which are highly weldable, but have mechanical properties that are not competitive with ...conventional wrought Al alloys. In addition, there is a need for new Al alloys with improved high temperature properties and thermal stability for applications in the automotive and aerospace fields. In this work, we considered laser powder bed fusion additive manufacturing of two alloys in the Al-Ce-Mg system, designed as near-eutectic (Al-11Ce-7Mg) and hyper-eutectic (Al-15Ce-9Mg) compositions with respect to the binary L → Al + Al
Ce eutectic reaction. The addition of magnesium is used to promote solid solution strengthening. A custom laser scan pattern was used to reduce the formation of keyhole porosity, which was caused by excessive vaporization due to the high vapor pressure of magnesium. The microstructure and tensile mechanical properties of the alloys were characterized in the as-fabricated condition and following hot isostatic pressing. The two alloys exhibit significant variations in solidification structure morphology. These variations in non-equilibrium solidification structure were rationalized using a combination of thermodynamic and thermal modeling. Both alloys showed higher yield strength than AM Al-10Si-Mg for temperatures up to 350 °C and better strength retention at elevated temperatures than additively manufactured Scalmaloy.
Copy–Move Forgery Detection (CMFD) helps to detect copied and pasted areas in one image. It plays a crucial role in legal evidence, forensic investigation, defence, and many more places. In the ...proposed CMFD method, a two-step identification of forgery is presented. In step one, the suspected image will be classified into either one of two classes that are forged or authentic. Step two is carried out only if the suspected is classified as forged, then forged location will be identified using the block-matching procedure. Initially, the suspected image is decomposed into different orientations using Steerable Pyramid Transform (SPT); Grey Level Co-occurrence Matrix (GLCM) features are extracted from each orientation. These features are used to train Optimized Support Vector Machine (OSVM) as well as to classify. If the suspected image is categorized into forged, then the suspected grey image is converted into overlapping blocks, and from each block, GLCM features are extracted. The proper similarity threshold value and distance threshold value can locate the forged region using GLCM block features. The performance of the proposed method is tested using standard datasets CoMoFoD and CASIA Datasets. The proposed CMFD approach results are consistent, even the forged image suffered from attacks like JPEG compression, scaling, and rotation. The OSVM classifier is showing superiority over the Optimized Naive Bayes Classifier (ONBC), Extreme Learning Machine (ELM) and Support Vector Machine (SVM).
We propose a theory of chiral fermion dark matter (DM) with an isospin-3/2 fermion of a dark sector SU(2)D gauge symmetry, which is arguably the simplest chiral theory. An isospin-3 scalar breaks ...SU(2)D down to a discrete non-Abelian group T′ and generates the DM mass. The SU(2)D gauge symmetry protects the DM mass and guarantees its stability. We derive consistency conditions for the theory and study its DM phenomenology. In some regions of parameters of the theory a two-component DM scenario is realized, consisting of a fermion and a boson, with the boson being the lightest T′ nonsinglet field. In the case of single-component fermionic DM, we find that internal consistency of the theory, perturbativity arguments, and the observed relic abundance limit the DM mass to be less than 280 GeV, except when s-channel resonance regions are open for annihilation. For a significant part of the parameter space, the theory can be tested in DM direct-detection signals at the LZ and XENONnT experiments.
A
bstract
We show that the rate for di-Higgs production at the LHC can be enhanced by a factor as large as 25 compared to the Standard Model value in the two Higgs doublet model, while being ...consistent with the known properties of the observed Higgs boson
h
. There are correlated modifications in
t
t
¯
h
and resonant
Zh
production rates, which can serve as tests of this model. Our framework treats both Higgs doublets on equal footing, each with comparable Yukawa couplings to fermions. The Cheng-Sher ansatz for multi-Higgs doublet model is shown to be strongly disfavored by current experiments. We propose a new ansatz for the Yukawa couplings of the Higgs doublets Φ
a
is proposed, where
Y
ij
(
a
)
=
C
ij
(
a
)
· min{
m
i
,
m
j
}/
v
, with
C
ij
(
a
)
being order one coefficients,
m
i the mass of fermion
i
and
v
the electroweak vacuum expectation value. Such a pattern of couplings can explain the observed features of fermion masses and mixings and satisfies all flavor violation constraints arising from the exchange of neutral Higgs bosons. The rate for
μ
→
eγ
decay and new contributions to CP violation in
B
s
−
B
¯
s
mixing are predicted to be close to the experimental limits.
In this experimental investigation, feasibility and performance of a polymer hybrid bio-nano composite were evaluated to remove malachite green (MG) under controlled environment conditions. The ...polymer hybrid bio-nanocomposite was characterized using FTIR, SEM and EDS. The influence of operating variables, namely effect of pH (2–11), nanocomposite dosage (20–100 mg), initial MG concentration (10– 200 mg/L), contact time (10–120 min) and temperature (298–318 K) were explored. The maximum removal efficiency (RE) of 99.79% was achieved at neutral pH at the dosage level of 50 mg with the initial MG concentration of 150 mg/L in 40 min. The equilibrium results revealed that the adsorption of MG data fitted to Langmuir isotherm (R2 > 0.970) indicating monolayer adsorption. The maximum adsorption capacity of polymer hybrid nanocomposite was found to be 384.615 mg/g. Kinetic studies were performed using five kinetic models and results showed the pseudo second order model fitted very well with the MG adsorption data (R2 > 0.990). The thermodynamic results confirmed that MG adsorption onto polymer hybrid nanocomposite is feasible and (ΔS ͦ = 0.2893 kJ/mol K), spontaneous (ΔH ͦ = 81.103 kJ/mol K) and exothermic (ΔG ͦ < 0). A mechanism is also proposed for the removal of MG using the polymer nanocomposite and identified that electrostatic attraction and hydrogen bonding as the major mechanism for removal of MG. FTIR results confirmed the presence of carboxyl (-COO) and hydroxyl (-OH) groups which helped in effective binding of cationic dye. The overall results revealed that polymer nanocomposite could be used as a potential adsorbent for removing MG from aqueous solution.
•Synthesized polymer based bio-nanocomposite was used for sorptive removal of MG dye.•Polymer based bio-nanocomposite removes 384.61 mg/g of MG dye.•Adsorption of MG follows Langmuir and Pseudo second order kinetics.•Thermodynamic study reveals that the process is feasible, spontaneous and exothermic.•Mechanism of MG removal was found to be electrostatic interaction and ion-exchange.
The fabrication of 3-D parts from CAD models by additive manufacturing (AM) is a disruptive technology that is transforming the metal manufacturing industry. The correlation between solidification ...microstructure and mechanical properties has been well understood in the casting and welding processes over the years. This paper focuses on extending these principles to additive manufacturing to understand the transient phenomena of repeated melting and solidification during electron beam powder melting process to achieve site-specific microstructure control within a fabricated component. In this paper, we have developed a novel melt scan strategy for electron beam melting of nickel-base superalloy (Inconel 718) and also analyzed 3-D heat transfer conditions using a parallel numerical solidification code (Truchas) developed at Los Alamos National Laboratory. The spatial and temporal variations of temperature gradient (G) and growth velocity (R) at the liquid-solid interface of the melt pool were calculated as a function of electron beam parameters. By manipulating the relative number of voxels that lie in the columnar or equiaxed region, the crystallographic texture of the components can be controlled to an extent. The analysis of the parameters provided optimum processing conditions that will result in columnar to equiaxed transition (CET) during the solidification. The results from the numerical simulations were validated by experimental processing and characterization thereby proving the potential of additive manufacturing process to achieve site-specific crystallographic texture control within a fabricated component.
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