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•A stable cobalt doped CuO NPs as reduction catalyst is synthesized by a thermal route.•Cobalt doping resulted in decrease in particle size of CuO NPs.•Positron annihilation lifetime ...spectroscopy revealed cobalt at grain boundaries of CuO.•Reduction of 4-NP to 4-AP in less than 3min using 2mg/L Co doped CuO catalyst.•Catalytic reduction explained by hydride transfer mechanism.
We present here a simple thermal route for synthesizing 5.1wt% cobalt doped CuO nanoparticles (NPs) as the optimized composition of the best heterogeneous CuO catalyst for catalytic reduction of toxic 4-nitrophenol to industrially beneficial 4-aminophenol. The reduction is completed in merely 3min in the presence of 8mM NaBH4 as reducing agent. The optimized catalyst dose was 2mg/L for converting 0.12mM 4-nitrophenol and the corresponding rate constant (k) for reduction reaction was 43.8×10−3s−1 per mg of catalyst. The catalytic reduction reaction was monitored by UV–vis spectroscopy method and by HPLC analysis. The mechanism is discussed in the light of hydride transfer phenomenon facilitated by large surface area and positive surface charge of the cobalt doped CuO nanoparticles. The cobalt doping resulted in: (a) increasing surface area due to decrease in particle size of the CuO NPs to 10nm, measured by HRTEM; (b) improve stability of the cobalt doped CuO NPs. The cobalt dopant occupied the grain boundaries of CuO to reduce the particle size as derived from positron annihilation lifetime spectroscopy. The X-ray photoelectron spectroscopy analysis of unused catalyst and the spent catalyst revealed occurrence of Co2+ and Co3+ states at the surface. While the X-ray diffraction studies of spent catalyst confirmed the inhibition of reduction of the surface CuO to metallic copper in the presence of NaBH4, attributable to cobalt doping. It was concluded that cobalt doping led to stable and efficient CuO NPs as catalyst for reduction reaction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Summary
Malaria, being an epidemic disease, demands its rapid and accurate diagnosis for proper intervention. Microscopic image‐based characterization of erythrocytes plays an integral role in ...screening of malaria parasites. In practice, microscopic evaluation of blood smear image is the gold standard for malaria diagnosis; where the pathologist visually examines the stained slide under the light microscope. This visual inspection is subjective, error‐prone and time consuming. In order to address such issues, computational microscopic imaging methods have been given importance in recent times in the field of digital pathology. Recently, such quantitative microscopic techniques have rapidly evolved for abnormal erythrocyte detection, segmentation and semi/fully automated classification by minimizing such diagnostic errors for computerized malaria detection. The aim of this paper is to present a review on enhancement, segmentation, microscopic feature extraction and computer‐aided classification for malaria parasite detection.
Lay description
Malaria is one of the parasitic infections, which transmits from one infected patient to healthy person through the bite of an Anopheles mosquito. Plasmodium species are responsible for malaria infection. Being an epidemic disease, malaria demands its rapid and accurate diagnosis for proper intervention. The most common and frequently followed diagnostic procedure is the visual assessment of microscopic images of peripheral blood smears and this is adopted as the gold standard for malaria characterization. This kind of manual analysis introduces inter‐observer variability leading to miss diagnosis. As a result delayed diagnosis happens. Apart from the limitations in conventional diagnosis process, it is very hard to get clinicians around the clock in rural areas. Scientists have shown an alternate way of diagnosis through computational evaluation of microscopic images which can help the medical community to overcome the aforesaid restrictions of conventional method. The technological advancement can also aid the tele‐diagnosis. Hence, the implementations and development of advanced computer vision techniques for microscopic image computing has become a popular field of research in digital pathology in recent times. Besides this research issue deals with real life problem and the outcome of this research has direct impact on mankind, which encourages researchers to get engaged in a pursuit. From the viewpoint of machine learning and pattern classification, automatically identifying the different malaria parasite infections and their sub‐types from light microscopic blood smear images is the challenging and essential task. The noisy interference, typical shape of infected erythrocytes (different types and sub‐types) and limited imaging characteristics make the computational analysis very challenging. Researchers have followed various computer vision approaches to deal with the difficulties and finally have come up with desired outcomes through minimizing diagnostic errors.
In this paper, authors represent a systematic chronological review of existing techniques of malarial characterization from microscopic images through addressing different stages of image processing methodology viz. pre‐processing (reducing staining variation, noise reduction etc.), segmentation (erythrocytes and chromatin detection), features extraction, potential feature set selection and pattern classification (characterization of malaria) and also comparing the performance of algorithms as per the information reported in literature. This review paper will certainly help new researchers to get a complete overview on microscopic image analysis for malaria screening and also assist them to find the gaps in existing literature, so that they can find some suitable approach for further modification to develop robust technique.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
•A novel sensitivity index is proposed for finding locations of shunt capacitors.•Fuzzy multiobjective function is formed and maximized using GA.•Substation reactive current is minimized for power ...factor improvement.•Optimum values of fixed and switched capacitors are obtained.•Net annual saving is also computed.
In this work a combination of fuzzy multiobjective and genetic algorithm (GA) based approach is proposed for optimal shunt capacitor placement to improve the substation power factor near unity, reduce the real power loss, and reduce the burden on the substation and to improve the voltage profile of the distribution network. In order to obtain best nodes for capacitor placement, a sensitivity index based on real power loss reduction and voltage profile improvement is considered. In the present work, an attempt is made to make reactive current component drawn by distribution network through substation is nearly zero such that power factor at the substation will be near unity. A fuzzy multiobjective function is formed considering substation reactive current component reduction, real power loss reduction, branch current constraint limit, minimum and maximum voltage limit satisfaction. The fuzzy multiobjective function is maximized using GA for obtaining the optimum sizing of fixed and switched shunt capacitors. Simulation results are shown to demonstrate the advantage of the proposed method compared to optimal shunt capacitor placement based on annual energy savings method.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
For many decades, the use of synthetic chemicals as drugs has been effective in the treatment of most diseases. Moreover, from ancient to modern history, many traditional plant based medicines are ...playing an important role in health care. Phytochemicals are natural bioactive compounds found in vegetables, fruits, medicinal plants, aromatic plants, leaves, flowers and roots which act as a defense system to combat against diseases. The phytochemicals from natural products cover a diverse range of chemical entities such as polyphenols, flavonoids, steroidal saponins, organosulphur compounds and vitamins. A number of bioactive compounds generally obtained from terrestrial plants such as isoflavones, diosgenin, resveratrol, quercetin, catechin, sulforaphane, tocotrienols and carotenoids are proven to reduce the risk of cardiovascular diseases and aid in cardioprotection which is the leading cause of death globally. The cardioprotective effects of the various phytochemicals are perhaps due to their antioxidative, antihypercholesteroemic, antiangiogenic, anti-ischemic, inhibition of platelet aggregation and anti inflammatory activities that reduce the risk of cardiovascular disorders. The multi-faceted role of the phytochemicals is mediated by its structure-function relationship and can be considered as leads for cardiovascular drug design in future. This review summarizes the findings of recent studies on selected phytochemicals as prophylactic and therapeutic agents in cardioprotection.
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•Cobalt doped Graphitic carbon nitride (g-CN) was synthesized chemically.•Thermal stability and Photoluminescence properties have been studied.•As prepared samples were used in ...visible light induced removal of toxic Eosin B dye.•Enhancement of photocatalytic activity after doping has been observed and discussed.
A simple method for synthesis of layered graphitic carbon nitride and its doping with cobalt has been reported. The as synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning and transmission electron microscope (FESEM, TEM), BET, UV–vis and photoluminescence (PL) spectrophotometer. XRD confirmed the proper phase formation whereas sheet like morphology was observed from FESEM and TEM study. EDX analysis confirmed the presence of cobalt. TG-DTA study revealed the increased stability of graphitic carbon nitride upon introduction of dopants. Surface area and pore size distributions of the pure and doped samples were studied from BET analysis. PL spectra of both the samples have been studied. Degradation of Eosin B dye was performed by both the samples. The doped sample showed enhancement of the visible light photocatalytic activity. It is speculated that the dopant induced trapping of electrons facilitates the separation of charged carriers thus giving better photocatalytic activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The kagome lattice
, which is the most prominent structural motif in quantum physics, benefits from inherent non-trivial geometry so that it can host diverse quantum phases, ranging from spin-liquid ...phases, to topological matter, to intertwined orders
and, most rarely, to unconventional superconductivity
. Recently, charge sensitive probes have indicated that the kagome superconductors AV
Sb
(A = K, Rb, Cs)
exhibit unconventional chiral charge order
, which is analogous to the long-sought-after quantum order in the Haldane model
or Varma model
. However, direct evidence for the time-reversal symmetry breaking of the charge order remains elusive. Here we use muon spin relaxation to probe the kagome charge order and superconductivity in KV
Sb
. We observe a noticeable enhancement of the internal field width sensed by the muon ensemble, which takes place just below the charge ordering temperature and persists into the superconducting state. Notably, the muon spin relaxation rate below the charge ordering temperature is substantially enhanced by applying an external magnetic field. We further show the multigap nature of superconductivity in KV
Sb
and that the Formula: see text ratio (where T
is the superconducting transition temperature and λ
is the magnetic penetration depth in the kagome plane) is comparable to those of unconventional high-temperature superconductors. Our results point to time-reversal symmetry-breaking charge order intertwining with unconventional superconductivity in the correlated kagome lattice.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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•Nickel doped Graphitic carbon nitride (GCN) was synthesized chemically.•Mott-Schottky was done to calculate the flat band potentials and donor densities of pure and doped ...samples.•Toxic Methyl Orange dye was degraded efficiently by doped samples in the presence of NaBH4 accompanied by hydrogen evolution.•Enhancement of catalytic activity with increasing doping concentration was studied in presence of varying amount of NaBH4.•A plausible mechanism for catalytic degradation was discussed in details.
A facile synthesis of transition metal-nickel doped graphitic carbon nitride (NiGCN) nanosheets with varying doping concentrations has been reported. X-Ray diffraction and Fourier transformed infrared spectroscopic study were performed to analyse the structural phase formation and different bonds present in the samples, whereas, field emission and transmission electron microscopic study provided the morphological information. The thermal stability of the samples was measured from the TG-DTA analysis. Photoluminescence spectroscopy was performed to elucidate the emissive property of the samples. The flat band potential of the samples was measured by Mott-Schottky analysis. First principle study was carried out to delineate the probable doping site of the Ni atom along with the effect of doping on the pure material. The samples were effectively utilized to degrade toxic methyl orange (MO) dye from water in the presence of sodium borohydride (NaBH4) without exploiting any visible light source. The plausible catalysis mechanism following a series of several chemical reactions has been discussed in details.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract
Unconventional superconductors often feature competing orders, small superfluid density, and nodal electronic pairing. While unusual superconductivity has been proposed in the kagome metals
...A
V
3
Sb
5
, key spectroscopic evidence has remained elusive. Here we utilize pressure-tuned and ultra-low temperature muon spin spectroscopy to uncover the unconventional nature of superconductivity in RbV
3
Sb
5
and KV
3
Sb
5
. At ambient pressure, we observed time-reversal symmetry breaking charge order below
$${T}_{{{\rm{1}}}^{*}\simeq$$
T
1
*
≃
110 K in RbV
3
Sb
5
with an additional transition at
$${T}_{{{\rm{2}}}^{*}\simeq$$
T
2
*
≃
50 K. Remarkably, the superconducting state displays a nodal energy gap and a reduced superfluid density, which can be attributed to the competition with the charge order. Upon applying pressure, the charge-order transitions are suppressed, the superfluid density increases, and the superconducting state progressively evolves from nodal to nodeless. Once optimal superconductivity is achieved, we find a superconducting pairing state that is not only fully gapped, but also spontaneously breaks time-reversal symmetry. Our results point to unprecedented tunable nodal kagome superconductivity competing with time-reversal symmetry-breaking charge order and offer unique insights into the nature of the pairing state.
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