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The two-dimensional (2D) layered molybdenum disulfide (MoS2) material represents a nominee potent for optoelectronic devices application. In this research work, the experimental characterizations of 2D- MoS2 thin films are reported in terms of various microscopic and spectroscopic techniques. The synthesized MoS2 thin films are grown by employing the pulsed laser deposition (PLD) procedure on SiO2/Si substrates. In order to monitor the deposition rates of ablated films, the buffer argon-gas pressures are varied during the pulsed laser deposition at substrate temperature of 700 °C. The field emission scanning electron microscopy and atomic force microscopy analyzes revealed a change in the surface morphology of MoS2 films when the buffer Ar-gas pressure is varied between 0 and 100 mTorr. For all samples, a 2H-phase is revealed from X-ray diffraction patterns, indicating a reflection (2θ) around 14.85°. By varying the deposition pressure of laser-ablated MoS2 films, the X-ray photoelectron spectroscopy divulged the chemical compositional elements and valence states of Mo and S on the surface of MS2 films with low density of defects. Analysis of the photoluminescence spectroscopy illustrated emission bands spanning from the visible (Vis) to near-infrared (NIR) regimes in the deposition pressures range ~ 0–100 mTorr. This is mainly owing to the change in the recombination of electron–hole pairs and charge transfer between the deposited MoS2 films and SiO2 substrate surface under various buffer gas pressures. Additionally, first-principles electronic structure calculations are performed to qualitatively examine the effect of native point-defect species (sulfur-monovacancy and sulfur-divacancy defects) on the electronic structure and optical properties of 2D- MoS2 sheets. It is unveiled that the variation of compositional sulfur-vacancy defect in MoS2 monolayer creates an in–gap defect levels above the valence states, leading to an acceptor character. Importantly, the enhancement in the optical absorption spectra divulged a shift in the optical gap from Vis-NIR window with the increase of sulfur vacancy contents in MoS2 single-layer. The identification of intrinsic point defects may be beneficial for photovoltaic energy conversion at higher wavelengths by designing next generation 2D-semiconductors, which could be of vital significance for growing 2D layers and multilayers into practical technologies.

Sandhanasamy Devanesan, Mohamad S AlSalhi Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11451, Kingdom of Saudi ArabiaCorrespondence: Mohamad S AlSalhi Email malsahi@ksu.edu.saBackground: Abelmoschus esculentus (L.) Moench, an economically important malvaceous vegetable crop popularly known as okra, is used in various culinary preparations and is rich in vitamins, minerals, and nutrients. The biological properties of okra flowers in relation to nanoparticle synthesis have not yet been reported.Materials and Methods: In the current study, silver nanoparticles (AgNPs) were synthesized using extracts of the flowers of A. esculentus. The characteristics of the AgNPs were studied using a UV-vis spectrometer, Fourier transmission infrared spectrophotometer (FTIR), X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray spectrometer (EDX). Antibacterial activity screening was performed using the agar well diffusion method, and cytotoxicity and cell viability studies were conducted using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.Results: The synthesized AgNPs were spherical and ranged in size from 5.52 to 31.96 nm, with an average size of 16.19 nm, as determined by UV-vis spectroscopy, FTIR, XRD, TEM and EDX. A. esculentus flower extract-mediated silver nanoparticles (AME-AgNPs) exhibited excellent activities in vitro studies, particularly in vitro cytotoxic and antiproliferative studies against cancer cell lines, such as the TERT-4 and A-549 cell lines. The antibacterial effects on the Gram-positive pathogens Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes and the Gram-negative pathogens Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Salmonella typhimurium and Shigella sonnei were tested. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values varied with the bacterial strain. The IC50 values of the synthesized NPs for the tested cell lines were close to that of a standard drug.Conclusion: Compared to other NPs the NPs synthesized in this study were smaller in size and exhibited a higher level of antibacterial activity, cytotoxicity and apoptosis at minimal concentrations, and this is the first study on okra flower-induced anticancer and antimicrobial activities.Keywords: Abelmoschus esculentus, silver nanoparticles, okra green pods, cell lines and cytotoxicity

The current investigation was taken to screen the phytoconstituents present in fruit endocarp various extracts of Nephelium lappaceum commonly called as Rambutan fruit and its anticancer property against human hepatocellular carcinoma (HepG-2) cells. Different analytical techniques including qualitative phytochemical analysis, cell viability assay (MTT), apoptotic nuclear staining (DAPI), DNA fragmentation assay, Attenuated total reflection (ATR) and Gas chromatography–mass spectrometry (GC–MS) spectral analysis were carried out. ATR and GC–MS study revealed the presence of functional groups and 9 compounds, respectively in methanol endocarp extract. The results obtained depicts that methanol endocarp extract profoundly controlled cell proliferation and caused shrinkage of HepG-2 cells from polygonal to spherical shape. DAPI staining revealed that methanol endocarp extract caused increased fragmentation of nucleus and DNA fragmentation, which can be taken as a sign of apoptosis. The anticancer potential of methanol fruit endocarp extract of Nephelium lappaceum than other extracts and could be used successfully in future drug delivery systems and other biomedical concerns.

This work compares the performance of three passive cooling systems in meeting thermal and indoor air quality requirements in a poultry house located in semi-arid climate. The first two systems are a direct evaporative cooler and a cross-flow dew point evaporative cooler supplying air through a conventional tunnel ventilation that achieves uniform thermal and indoor air quality conditions. The third system is a dew-point evaporative cooler combined with a localised ventilation system to further reduce air and water consumption. To achieve these objectives, a modular analysis was adopted where mathematical models were developed for the evaporative coolers and the tunnel-ventilated poultry house module. Moreover, a computational fluid dynamics model was developed and experimentally validated for the compartment conditioned by the localised system. The evaporative coolers were sized and the hourly variation in the required fresh air and water supply was determined for the cooling season. Results of the economic analysis showed that the cost of the dew-point evaporative cooler was 6.8% lower than that of the direct evaporative cooling, with better compliance to poultry house thermal and air quality requirements. Using localised ventilation instead of conventional with the dew point apparatus further reduced costs by 4.7%, while achieving similar conditions of temperature and air quality.

Background The antioxidant potential and antiproliferative activity of the extracts of Nigella sativa seeds (Black Cummins) and honey formulations are to be explored. Method The gas chromatography-mass spectrum (GC–MS) and Thin Layer Chromatography (TLC) fingerprint of Black Cummins and Honey formulation revealed alkaloid, saponin, volatile oil, flavonoid, glycosides, sugar, and phenolic compound in the extract. GC–MS profiling of the cold extract of Nigella sativa seeds and honey formulation shows peaks for eleven fractions of compounds. Using TLC, the phenolic compounds of Nigella sativa seeds and honey formulations were separated. Results The current study discovers the cytotoxic effect of black Cummins seeds and honey formulation on human ovarian cancer (PA-1) cell line as assessed by MTT assay. PA-1 cells were inhibited with the increasing concentration of Nigella sativa seeds extract and honey formulation. Conclusion The study validates the importance of the tested extracts in the treatment of cancer.

The M. citrifolia, commonly called starvation fruit, plays an essential role in daily dietary intakes, as it contains several vitamins, phytochemicals, and electrolytes. These constituents have several biological activities that are anti-tumor, antibacterial, antiviral, antifungal, and play a role in the immune system. The silver nanoparticles (AgNPs) were synthesized using a more uncomplicated and fast means using the M. citrifolia fruit samples. The Silver ions (Ag+) readily get reduced to (Ag0) to perform M. Citrifolia AgNPs hence the fruit extracts of M. Citrifolia can be considered potential lowering agents. The preliminary confirmation was done qualitatively by change of color into brownish-black, and the color change was observed due to bio-reduction and the Surface Plasmon Resonance (SPR) vibration. It was established by the absorbance peak at 430 nm using UV–Visible spectral analysis. Scanning Electron microscopy (SEM) showed the particle size ranging from 12 to 26 nm. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of the functional groups from synthesized M. citrifolia AgNPs. The biochemical studies were supported by the effect of antioxidant and anticancer properties of M. citrifolia AgNPs. The pathological changes were studied using hematoxylin, and Eosin staining in Albino mice, which was no tumor (Ehrlich ascites carcinoma) cell invasion exhibited in Fluorouracil treated group. The present investigation proves that the M. citrifolia fruit extract derived AgNPs is a promising antioxidant agent to treat liver cancer.

The deployment of biological resources for the synthesis of nanoparticles of metals and metal oxides is the latest addition to green chemistry. The present work describes the use of aqueous stem extracts of Aristolochia indica and Indigofera tinctoria for the synthesis of silver and gold nanoparticles (Ag and Au NPs). The synthesized NPs were characterized by UV–Vis., FT-IR, TEM, XRD and EDAX analyzes. The antioxidant activities of functionalized Ag and Au NPs were studied by the DPPH method and the nanoparticles showed greater antioxidant activity than that of the extract; AgNPs synthesized by A. indica showed antioxidant activity of 84%. The in vitro cytotoxicity of the Ag and Au NPs was assessed by the MTT assay method using the HeLa cell line and the NPs synthesized by A. indica showed nearly 100% toxicity. DNA binding capacity was investigated using calf thymus-DNA by UV–Vis spectra, the hyperchromism shift inferred the groove binding of nanoparticles and the binding constants (1.66 × 107 and 1.06 × 107 and 0.77 × 107 and 1.59 × 107 M−1 for the NPs of Ag and Au synthesized by A. indica and I. tinctoria respectively) indicate a high potential of these nanoparticles for the administration of drugs.

Vanadium oxides are promising candidates for cathode materials in aqueous zinc-ion batteries (ZIBs) with low cost and high capacity yet requirements for long cycling necessitate the development of increasingly stable structure. This study reports a structural engineering method by incorporating K+ into hydrated vanadium pentoxide (V2O5·nH2O, VOH) to achieve unique hydrated vanadate (KV12O30-y·nH2O, KVOH). In contrast to previously reported works, K+ introduction leads to a new phase of KVOH with faster ion diffusion kinetics and better long-term cycling stability. This work establishes an understanding of the role of K+ incorporation in KVOH which goes beyond its conventional categorization as an agent for interlayer spacing adjustment, reflecting in maintaining structure flexibility for effective Zn2+ insertion/extraction even at high rates, improving materials conductivity by the electron hoping of V4+/V5+ and acting as a stabilizer to accommodate structural contraction/expansion with smaller voltage hysteresis and higher reversibility. KVOH displays a remarkable capacity of 436 mAh g−1 at 0.05 ​A ​g−1, maintains 227 mAh g−1 at 10 ​A ​g−1, which is better than VOH and the majority of reported monovalent and multivalent metal ions introduced in vanadates. KVOH exhibits excellent cycling stability with 92% capacity retention over 3000 cycles at 5 ​A ​g−1, high energy density (308 ​Wh kg−1) and power density (7502 ​W ​kg−1), as well as improved energy efficiency. These characteristics recommend KVOH cathodes for use in high-performance aqueous ZIBs.

The photo catalytic degradation, a proven chemical process used for the decontamination of organic/inorganic pollutants and microorganisms in water was implemented. In this work for the selective killing of cervical cancer cells (HeLa cells) by using nano-composite of ZnO (Zinc Oxcide), WO3 (tungsten oxide) and (n-WO3/ZnO) as a photo-catalyst under the irradiation of visible light. All the three nanostructured semiconducting materials (WO3, ZnO and n-WO3/ZnO) were synthesized by facile chemical precipitation method and their morphological and optical characterization studies were carried out to elucidate the observed enhancement in the photo-catalytic killing of HeLa cancer cells with n-WO3/ZnO as a photo-catalyst. After 60 min of photo-catalytic reaction with n-WO3/ZnO as a photo-catalyst, a survival viability of HeLa cancer cells as low as 15% was achieved (nearly 85% of killing), as compared to 65% of HeLa cancer cell survival viability (nearly 35% of killing) with individual use of WO3 and ZnO as photo-catalysts under the same irradiation and experimental conditions. This improved photo-catalytic killing of HeLa cancer cells using n-WO3/ZnO in the visible spectral region is attributed to the enhanced visible light absorption and reduced electron hole recombination, characteristically brought about in the n-WO3/ZnO composite material. As photo-catalytic killing of the cancer cells can be selective, localized and reasonably efficient, in principle, this method can be considered as a non-invasive targeted treatment option for killing any type of cancer cells. HeLa cells, in particular are the cervical cancer cell and the tumors in and around cervix, containing HeLa cells can be non-surgically accessed and photo-catalytically treated with appropriate photo-catalyst and light source.

A novel biological approach is attempted to convert the human urinary waste into a well-designed bionanomaterial. In the present study, biological activated ammonia gas (NH3(g)) mediated synthesis of hydroxyapatite material (B-HAp) and then impregnation of silver nanoparticles (AgNPs) on the B-HAp material surface was performed by photoreduction method and was followed by an evaluation of its antibacterial activity and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. X-ray diffraction spectroscopy (XRD) and Field emission-scanning electron microscopy (FE-SEM) were engaged to analyze the synthesized materials. Analytical studies revealed the morphology of the crystalline B-HAp synthesized by biologically activated NH3(g) as spherical shaped with AgNPs impregnated on over it. Atomic Absorption Spectrometers (AAS) estimated 2–7 ppm of Ag+ ion were released from the 100 ppm of Ag concentration was impregnated with B-HAp material (B-HAp-Ag-10). It was also found to be an excellent performance of antibacterial activity against Pseudomonas sp, E.coli and S. aureus. The cell- material interaction study of the thus synthesised B-HAp-Ag-10 was found to exhibit a minimal cytotoxicity level when incorporated in MG63 osteosarcoma cell lines, thus confirming the prospective biological application of our material in the biomedical field.

Purpose The present study synthesized silver nanoparticles (AgNPs) using the aqueous extract of a traditional medicinal product consisting of an oleoresin (a combination of macromolecules of carbohydrates and proteins) exuded from the rhizome of the plant Ferula foetida (asafoetida gum) and evaluated its biological properties. Materials and methods The silver nanoparticles synthesized using asafoetida gum (As-AgNPs) were characterized using UV/Vis spectroscopy, fourier infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM) and EADX. The cytotoxicity and antimicrobial activity As-AgNPs were evaluated against MCF-7 cell lines and selected microbial pathogens, respectively. Results The synthesized silver nanoparticles were crystalline in nature with a spherical shape. The average particle size was 5.6-8.6 nm. The cytotoxicity of the synthesized As-AgNPs was evaluated against MCF-7 cell lines, and the As-AgNPs were found to be effective in inhibiting the multiplication of cancer cells. The As-AgNPs exhibited significant antimicrobial activity towards E. coli, K. pneumoniae and C. albicans. The MIC of the synthesized As-AgNPs was 7.80 μg/mL for E. coli ATCC 25922, Salmonella sp. WS50- and S. typhi; 15.60 μg/mL for S. typhimurium and S. aureus WS10, and 31.20 μg/mL for K. pneumoniae and S. aureus ATCC 43300-MRSA. In addition, MIC values of 15.60 μg/mL for C. albicans ATCC8436 and 31.20 μg/mL for C. krusei ATCC6258 were obtained. Conclusion As asafoetida is a good traditional medicine, its involvement in the synthesis of AgNPs led the silver nanoparticles to exhibit good cytotoxic and antimicrobial effects.

Nanobiotechnology is an exuberant sphere of science that exhibits potential application in cancer therapy, targeted chemotherapy, molecular diagnosis and molecular imaging. Present investigation discloses green route synthesis of selenium nanoparticles leading to functionalization as anti leukemia nanomaterial. Emergence of resistance over cancer radiotherapy and chemotherapy is found to be the key factor behind the clinical treatment failure and recurrence. Selenium nanoparticles (SeNPs) with distinctive physicochemical features emerged as a novel nanocarrier and therapeutic agent with broad spectrum of medicinal properties. On the basis, biogenic technology has been proposed to synthesize selenium nanoparticles using Cassia auriculata and characterized using standard techniques. Newly synthesized selenium nanoparticles’ UV intense peak is achieved at 252 nm with crytalline surface morphology clear in SEM analysis. Cassia auriculata mediated selenium nanoparticles’ TEM analysis exhibits polydispersed with 10–20 nm. FTIR spectrum confirms the reduction of carboxyl group and capping of alkane group in Cassia auriculata synthesizes the selenium nanoparticles and its anti cancer potentiality has been explored by anti-leukemia activity using in vitro studies.

Pristine ZrO2 and molar ratios of Cu-doped ZrO2 nanoparticles were synthesized by chemical precipitation. The XRD pattern of pristine ZrO2 and Cu-doped ZrO2 nanoparticles shows the formation of t-tetragonal phase and shifting of tetragonal phase to monoclinic phase. The average crystallite sizes of the pristine ZrO2 and Cu-doped ZrO2 nanoparticles were calculated as 2.9, 4.65, 4.76, 5.02, and 4.96 nm, respectively. The Cu (0.06 M)-doped ZrO2 nanoparticles are present as spherical morphology and high agglomeration was confirmed by FE-SEM and TEM analyses. The XPS spectra affirmed the presence of Cu2+, Zr4+, and oxygen ions in the Cu (0.06 M)-doped ZrO2 nanoparticles. The Cu-doped ZrO2 nanoparticles exhibit two energy gaps at 5.30 and 3.05 eV, 5.21 and 2.22 eV, 4.65 and 2.11 eV, and 4.44 and 2.65 eV. The surface defects and oxygen vacancies were analyzed by PL and ESR spectroscopy. The ESR spectra are clearly asymmetric in shape and contain a peak signal related to the presence of the copper species (Cu2+) in the distorted tetragonal coordination of ZrO2. The photocatalytic activities of Cu (0.06 M)-doped ZrO2 nanoparticles were successfully sought on degradation of the two azo dyes: methyl violet and methyl blue under sunlight irradiation. Cu (0.06 M)-doped ZrO2 showed complete degradation at 70 min. The reusability of Cu (0.06 M)-doped ZrO2 nanoparticles shows maximum degradation efficiency for six successive runs.

Collisional intermolecular interactions between excited states form short-lived dimers and complexes that lead to the emergence of excimer/exciplex emission of lower energy, a phenomenon which must be differentiated from the photoluminescence (PL) arising from the monomeric molecules. Although the utilization of noncovalent bonding interactions, leading to the generation of excimer/exciplex PL, has been investigated extensively, precise control of the aggregates and their persistence at very low concentrations remains a rare phenomenon. In the search for a fresh approach, we sought to obtain exciplex PL from permanent structures by incorporating anthracene moieties into pyridinium-containing mechanically interlocked molecules. Beyond the optical properties of the anthracene moieties, their π-extended nature enforces [π···π] stacking that can overcome the Coulombic repulsion between the pyridinium units, affording an efficient synthesis of an octacationic homo[2]catenane. Notably, upon increasing the ionic strength by adding tetrabutylammonium hexafluorophosphate, the catenane yield increases significantly as a result of the decrease in Coulombic repulsions between the pyridinium units. Although the ground-state photophysical properties of the free cyclophane and the catenane are similar and show a charge-transfer band at ∼455 nm, their PL characters are distinct, denoting different excited states. The cyclophane emits at ∼562 nm (quantum yield ϕ

Two chromium resistant alkalophilic bacterial strains (CRAB), namely Bacillus cohnii SR2 and Bacillus licheniformis SR3 were isolated and identified from tannery effluent. Bioreduction of chromium (VI) into chromium (III) by CRAB was investigated in the present study. Optimization of process parameters with respect to bioreduction percentage was studied by Response Surface Methodology (RSM) software, v12. Both the strains were found to achieve highest chromium (VI) bioreduction of 94 and 95% in 100 mg/L at the end of 25 h at pH 9.0. At an optimized concentration of 550 mg/L, a maximum bioreduction of 82 and 90% by SR2 and SR3 was noted within 25 h. In addition, both the strains showed tolerance to chromium until 1000 mg/L. Scale-up studies using Air lift bioreactor system by CRAB with real tannery effluent showed 100% bioreduction within 8 h. Therefore, this study signified the astonishing bioreduction capability of CRAB isolates that was quite evident in scale-up studies too. Keywords: Alkalophilic, Bioreduction, Chromium resistant, Response surface methodology, Tannery effluent

The ZnO particle with varieties of morphology was prepared from ice-cube of zinc ammonium complex at boiling water surface in 1 min induction of thermal shock. The zinc ammonium complex in ice cube was developed using zinc acetate and biologically activated ammonia in 1 hr and kept in the freezer. Temperature gradient behaviour of the water medium during thermal shock was captured by the thermal camera and thermometer. Morphology study revealed a variety of flower-like ZnO particles with variable size from 1.0 to 2.5 μm. Further, ZnO particle morphologies were tuned by adding trisodium citrate and hexamine to obtain uniform spherical (2–3 μm) and flower (3–4 μm) shapes, respectively. XRD patterns revealed that all ZnO samples are of a hexagonal structure. Photocatalytic inactivation of E. coli has been investigated using various particle morphologies of ZnO in an aqueous solution/overcoated glass slide under sunlight. The photo-inactivation of E. coli by ZnO particles in suspension condition was better when compared to a coated glass slide method. AFM study confirmed the destruction of bacterial cell wall membrane by the photocatalytic effect. The particles morphology of photocatalyst is well dependent on antibacterial activity under sunlight. Keywords: Ice-cube, XRD, E. coli, Antibacterial activity, AFM

The worldwide increase in malignancy rates has caused an increase of research interest for compelling and safe materials used for cancer treatment. A standout amongst the most pervasive types of treatment for malignant growth is photodynamic therapy (PDT), which is viewed as an alternative to radiotherapy and chemotherapy. PDT utilizing metal-based nanoparticles (NPs) is anticipated to be a useful approach for the treatment of malignant tumors. In the present study, NiO NPs were synthesized via a chemical co-precipitation (CPT) technique and characterized using XRD, SEM, TEM, UV–Visible spectroscopy, and EDX spectroscopy. The particle size was measured to be in the range of 90–120 nm using different characterization techniques. UV–visible spectroscopy showed the maximum absorption band was 340 nm, which confirmed the formation of the NiO NPs. Subsequently, the cytotoxicity of the NiO NPs was studied using a HeLa cancer cell line at various concentrations (10–180 μg/mL). An MTT assay was carried out and the reactive oxygen species (ROS) were investigated to determine the cell killing effects and their relationship with the loss of cell viability upon treatment with NiO alone or in the presence of light. Our results show that a light dose of 100 J/cm2 and NiO NPs concentration of 180 μg/mL exhibited an effective PDT outcome on cervical cancer cells. These key outcomes support the photokilling effect of NiO NPs as a potential treatment for cervical malignancy and their in-vivo application is inferred from their biocompatible properties. Keywords: NiO NPs, Cytotoxicity, ROS, Cellular morphology

Development of energy storage technologies is thriving because of the increasing demand for renewable and sustainable energy sources. Although lithium-ion batteries (LIBs) are already mature technologies that play important roles in modern society, the scarcity of cobalt and lithium sources in the Earth’s crust limits their future deployment at the scale required to supplant fossil fuels. Dual-ion batteries (DIBs) based on a different combination of chemistries are emerging-energy storage-systems. Conventional DIBs apply the graphite as both electrodes and a combination of organic solvents and lithium salts as electrolytes. This configuration is fascinating because of its high working potential (>4.5 V vs. Li/Li+), potentially high energy density, high safety and low cost. But it also accompanies some negative issues like limited capacity of intercalation-type graphite electrodes, cyclic stability endangered by large anions intercalation and solvent co-intercalation and electrolyte decomposition under high voltage. This review aims at pointing out the challenges in the current work on DIBs with subcategories of positive and negative electrodes (cathode and anode), and electrolytes and comparing the strategies for improvements with better fundamental understanding of DIBs.

Herein, nanorods-like ZnO particles was prepared by effective chemical synthesis process and carbon nanoplates supported ZnO nanorods (ZnO/C) was prepared by wet chemical process. The synthesized materials were characterized by various instrumental analysis via power XRD, UV–vis DRS, FESEM and EDX spectroscopy. The synthesized samples were utilized as competent photocatalysts for the remediation wastewater. The visible light-driven photocatalytic performances of the samples was assessed by the photodegradation of methylene blue. Compared to pure ZnO, the ZnO/C photocatalyst showed an excellent photocatalytic performances by efficiently degrading (around 95%) of MB as targeted organic pollutants within the irradiation time period of 80 min. The improved photodegradation activity of ZnO/C might be due to an improved absorption of ZnO/C photocatalyst in the visible region as well as good structural morphology and surface state which was accredited to an efficient separation of charge carriers and hindered recombination at ZnO/C interfaces. The higher photo-stability and photocatalytic performance was exposed that ZnO/C samples can be a potential photocatalysts for the applications of environmental remediation. Finally, a plausible degradation pathway mechanism for an enhanced activity of ZnO/C has been proposed. Keywords: Methylene blue, Photocatalysis, Photodegradation, Radicals trapping, Visible light, ZnO/carbon nanoplates

Objective Absorption spectroscopy and calorimetry has been a very convenient tool in the diagnosis of a variety of diseases. In recent times, fluorescence emission spectroscopy is proposed to be a more sensitive technique for disease detection. Methods In this context, fluorescence emission spectra have been obtained from blood and urine samples from clinically suspected subjects of cancer (N = 40) as compared with normal control samples. Results Based on a certain set of fluorometric ratio parameters the samples of suspected subjects were scored positive or negative to assess the validity of the spectral technique in detecting cancer, irrespective of organ or stage. This study was done in the premises of a hospital with the blinded sets of blood and urine samples and it has classified correctly 30 out of 40 (75% true positive) indicating a reasonable level of accuracy of this new, simple technique Conclusion It could be of significant value as the first-line defense in the screening process of any cancer.

In this investigation, we have analyzed the structural, electrical, and optical behaviors of pure and composite thin films which are obtained from 2D monolayer molybdenum disulfide (MoS2) flakes, conjugated oligomer (CO) 1,4-Bis(9-ethyl-3-carbazo-vinylene)-9,9-dihexyl-fluorene (BECV-DHF), and by combining CO (BECV-DHF) with MoS2 in forms of CO/MoS2 composites. All the samples are coated on SiO2/Si substrates using the spin coating procedure where a spin-coating solution has been obtained by dispersing CO and MoS2 in ethanol or toluene. The structural morphology of MoS2 films and CO/MoS2 films of various thicknesses are analyzed using field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and profilometer. These experimental results confirm the formation of MoS2 layer composite with oligomer nanocrystals. The optical properties of MoS2, CO, and CO/MoS2 films showed that the increased film thickness shifted the spectral peaks towards near infrared (NIR) and ultraviolet?visible (UV) regions of the electromagnetic spectrum. Moreover, devices such as solar cells, flexible memory cell and MOSFET were designed. The I-V characteristics of these devices show that CO/MoS2 composite films could serve as potential candidates for organic-inorganic nano-electronic device applications. ? 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

In the present study, produced water sample collected from the Indian crude oil reservoir is used to enrich the bacterial communities. The impact of these enriched bacterial communities on the biodegradation of crude oil, biofilm formation, and biocorrosion process are elucidated. A crude oil degradation study is carried out with the minimal salt medium and 94% of crude oil was utilized by enriched bacterial communities. During the crude oil degradation many enzymes including alkane hydroxylase, alcohol dehydrogenase, and lipase are playing a key role in the biodegradation processes. The role of enriched bacterial biofilm on biocorrosion reactions are monitored by weight loss studies and electrochemical analysis. Weight loss study revealed that the biotic system has vigorous corrosion attacks compared to the abiotic system. Both AC-Impedance and Tafel analysis confirmed that the nature of the corrosion reaction take place in the biotic system. Very less charge transfer resistance and higher corrosion current are observed in the biotic system than in the abiotic system. Scanning electron microscope confirms that the dense biofilm formation favoured the pitting type of corrosion. X-ray diffraction analysis confirms that the metal oxides formed in the corrosion systems (biotic). From the metagenomic analysis of the V3-V4 region revealed that presence of diverse bacterial communities in the biofilm, and most of them are uncultured/unknown. Among the known genus, Bacillus, Halomonas, etc are dominant in the enriched bacterial biofilm sample. From this study, we conclude that the uncultured bacterial strains are found to be playing a key role in the pitting type of corrosion and they can utilize crude oil hydrocarbons, which make them succeeded in extreme oil reservoir environments.

Flashing electron ratchets oscillate a periodic asymmetric potential to rectify nondirectional forces and thereby produce directional transport of electrons with zero source-drain bias. The relationship between the oscillation frequency of the potential and the ratchet (short-circuit) current reflects microscopic mechanisms of charge transport within the device. This paper describes experimental mappings of the “optimal frequency(ies)” of the ratchet fpeak—the oscillation frequencies that produce the largest ratchet current—to the carrier concentration, nh, and to the linear field effect transistor mobility, μh, for a poly(3-hexylthiophene-2,5-diyl) (P3HT) transport layer. Measurements on multiple devices, multiple P3HT films per device, and a range of annealing and photoexcitation conditions yield the empirical relationships fpeak ∝ nh and fpeak ∝ μh2/3. Finite-element simulations suggest the sublinear relationship between mobility and peak frequency arises due to a combination of damped and inertial mot...

In this work, we fabricated solar cells and panel using net-like CoS2 nanostructure as Counter Electrode (CE) spray coated on Ag grid embedded on flexible plastic Poly-Ethylene Terephthalate (PET) substrate. The spray coated CoS2 thin film revealed its form to be a hierarchical net-like nano-structure. The TiO2:N3 dye and phthaloylchitosan-based gel-polymer electrolyte as the redox electrolyte layers of Flexible Organic Solar Panel (FOSP) was fabricated using screen printing technique. Then both segments were sandwiched to form flexible solar panel. The fabricated solar cell showed a Power Conversion Efficiency (PCE or η) of 7.09% with a fill factor (FF) of 0.64, Jsc of 17.51 mA/cm2, and an open circuit voltage (Voc) of 0.65 V, which was comparable to that of Platinum (Pt) CE (η = 7.82%). Similarly, for FOSP showed PCE of 7.04%, FF of 0.62, Isc of 67 mA and Voc of 60 V. The FOSP was connected to buck converter with Maximum Power Point Tracking (MPPT) using a modified Fractional Open Circuit Voltage (FOCV) combined with Duty-cycle Derivative of Output Voltage (DDOV) algorithms, Buck Boost converter (BBC) works from 60 to 5.8 V in buck mode, the output is connected to a battery. For voltages less than 8 V the power converter works in boost mode (up to 3.8 V), a micropower harvester would be very useful many handheld gadgets. Keywords: Duty-cycle derivative of output voltage, Spheroids agglomerated nanocluster CoS2 CE, A Pt-free counter electrode, Flexible DSSC, Dye-sensitized solar cells, and panel, Gel-polymer electrolyte

The essential oil (EO) composition of Vetiveria zizanioides and Ocimum basilicum were analysed and its post-harvest protective properties of jack fruits (Artocarpus heterophyllus Lam.) against the spoilage bacteria and fungi were investigated. Hydrodistillation and GC–MS analysis documented the presence of various components, including, hexamethyl-cycloocta-1,3,6-triene, d -Cadinene, Cedren-8-en-15-ol, 2-Isopropenyl-1,3,5-trimethylbenzene, metylchavico and trans-sabinene in V. zizanioides and O. basilicum, respectively. V. zizanioides EO showed potent activity against Staphylococcus aureus and Proteus mirabilis and the zone of inhibition was 32 ± 2, 26 ± 0 mm, respectively. Whereas, O. basilicum oil showed potential activity against Streptococcus mutans (28 ± 3 mm) and Rhizopus microsporus (28 ± 3 mm). EO of V. zizanioides exhibited high activity against S. aureus (MIC = 50 ± 0 μg/ml), followed by P. mirabilis (MIC = 75 ± 5 μg/ml). The EO from O. basilicum displayed high activity against S. mutans (MIC = 50 ± 0 μg/ml). The EOs from these two sources showed synergistic effect on S. mutans (29 ± 2 mm), P. mirabilis (27 ± 2 mm), Enterobacter aerogenes (13 ± 3 mm), S. aureus (34 ± 3 mm), Penicillium notatum (22 ± 3 mm) and R. microsporus (33 ± 3 mm). In addition, the EO at 100 μg/ml concentration V. zizanioides (79 %) and O. basilicum (83 %) documented significant antioxidant activity. The mixture of Vetiver roots and Ocimum oil suppressed the growth of P. notatum. The colony area was 32 ± 3.5 cm2 after incorporation of 5 μl EO concentration. However, at 25 μl concentration, colony area decreased as 4.2 ± 1 cm2 after 7 days of incubation and spore germination was completely suppressed. R. microsporus growth was decreased at 100 μl concentration. EO significantly reduced the spreading of rot causing P. notatum on the surface of jack fruit is an additional advantage. Overall, the results concluded that the obtained EO counter the severity of P. notatum and R. microsporus on the surface of jack fruit and protect from spoilage and deterioration.

This paper reports the preparation of composite CuO/ZnO nanoparticles by facile precipitation route and their photocatalytic activity against organic dyes. The red shift caused in the UV–Vis absorption spectrum suggests the enhancement of visible light photocatalytic activity of the material. The collective vibrations of Cu–O and Zn–O in FTIR spectrum clearly illustrate the formation of composite CuO/ZnO nanoparticles. Powder XRD profile suggests the formation of highly crystalline material and the chemical states of the elements is investigated by XPS analysis. A slightly agglomerated cluster-like structure of the particles is visualized by SEM analysis and EDS mapping illustrates the homogeneous distribution of the sample, which is most favorable for the photocatalysis analysis. The photocatalytic activity of material is studied against degradation of Rhodamine B and Methylene blue dyes using simulated solar light irradiation. The dielectric analysis of the composite CuO/ZnO nanoparticles demonstrates the enhanced dielectric permittivity and low loss factor in comparison with pure CuO and ZnO nanoparticles.

Oxygen vacancies (Vo) play a crucial role in energy storage materials. Oxygen-vacancy-enriched vanadium pentoxide/poly(3,4-ethylenedioxythiophene) (Vo-V2O5/PEDOT) nanocables were prepared through the one-pot oxidative polymerization of PEDOT. PEDOT is used to create tunable concentrations of Vo in the surface layer of V2O5, which has been confirmed by X-ray absorption near edge structure (XANES) analysis and X-ray photoelectron spectroscopy (XPS) measurements. Applied as electrode materials for supercapacitors, the electrochemical performance of Vo-V2O5/PEDOT is improved by the synergistic effects of Vo in V2O5 cores and PEDOT shells with rapid charge transfer and fast Na+ ion diffusion; however, it is compromised subsequently by excessive Vo in consuming more V5+ cations for Faradic reactions. Consequently, the specific capacitance and the energy density of Vo-V2O5/PEDOT nanocables are significantly enhanced when the overall concentration of Vo is 1.3%. The migration of Vo renders an increased capacitanc...

Herein, sponge-like bismuthoxychloride (BiOCl) and hematite iron oxide (α-Fe2O3) were synthesized by simple and inexpensive method via two-step process, including hydrothermal and solution combustion method. The BiOCl/α-Fe2O3 composite photocatalysts were prepared by incorporating various weight ratios of α-Fe2O3 on BiOCl by a low-cost wet chemical process. The chemical interaction, phase and crystalline nature of the samples were ascertained by Fourier transform infrared spectroscopy (FT-IR) and x-ray diffraction (XRD). Further, the surface morphology and optical properties of the fabricated materials was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis diffuse reflection spectroscopy (DRS). Photocatalytic activities of the fabricated samples towards the photocatalytic degradation of direct red 81 (DR81) was evaluated under ultraviolet light illumination. The BiOCl/α-Fe2O3 composites showed remarkably enhanced photo-induced catalytic performances. The photocatalyst with optimal content of α-Fe2O3 with the highest photocatalytic performance was observed to 1%-BiOCl/α-Fe2O3. The synergistic improvement in the photodegradation of BiOCl/α-Fe2O3 sample may be because of an expansion in the noticeable light absorption efficiency as well as fast photo-generated charge separation. A probable mechanism for the photocatalytic degradation has been proposed for the catalytic performance of BiOCl/α-Fe2O3 photocatalyst. Keywords: Bismuthoxychloride, Direct red 81, Iron oxide, Photocatalysis, Photodegradation

In this work, we report on the time resolved spectroscopy of amplified spontaneous emission (ASE) from the conjugated oligomer (CO) 9,10-Bis[(9-ethyl-3-carbazoyl)-vinylenyl]-anthracene (BECVA) only upon energy transfer from another oligomer 1,4-Bis(9-ethyl-3-carbazo-vinylene)-9,9-dihexyl-fluorene (BECV-DHF). BECVA do not dissolve readily in tetrahydrofuran (THF) at room temperature, but completely dissolved when the temperature of the solution (THF & BECVA mix) was risen to 65 °C and remained dissolved even after cooling to room temperature. The process of heating and dissolving do not affect the performance of the CO. The heat-treated solutions were used to perform all experiments, unless mentioned. The absorption spectra indicated no aggregate formation upon increasing concentration, but the fluorescence spectra were very different for several concentrations of the solution, indicating the presence of the excimer. Pure BECVA in THF was pumped at various pump powers and concentrations. This produced only a broadband emission (from 500 to 750 nm) with a FWHM of 250 nm, which has potential applications in white light OLED. Next, we tried to produce ASE using the energy transfer process from a conjugated polymer (CP) poly (9,9-dioctylfluorenyl-2, 7-diyl) (PFO); however, this did not produce ASE, which could be due to the significant hindrance of the macromolecular PFO. The intensity of the BECVA spectra was enhanced with energy transform from PFO. The output was a broadband emission ranging from 400 to 750 nm (FWHM 350 nm). Finally, we added the oligomer BECV-DHF in solution (THF) to the BECVA solution at optimal pump power and concentration of donor (BECV-DHF), and the super-irradiant laser was produced from BECVA at 500 nm with a FWHM of 6 nm. The ultrafast dynamics of the BECVA solution under high pump power excitation and different energy donor (PFO and BECV-DHF) were extensively studied in this work. To the best of our knowledge, this is the first report of a CO that does not intrinsically produce ASE, but produces efficient ASE only via the energy transfer process by another CO.

In this paper, the spectral and electrical properties of a conjugated polymer poly [(9, 9-dioctyl-2, 7-divinylenefluorenylene)-alt-co-(1, 4-phenylene)] (PFO–MEH–PPV) with poly[3-(2-ethyl-isocyanato-octadecanyl) thiophene] (PECOD) in thin films have been studied. First, PFO–MEH–PPV and PECOD were dissolved in tetrahydrofuran and chloroform respectively for different concentrations. These solutions were deposited on glass substrates to form thin films with different thicknesses. The absorbance and photoluminescence spectra for each individual pure polymer were recorded and contrasted with those for blended conjugated polymer’s films to determine the effect of blending on the absorption and photoluminescence. Finally, we present a study on the processing and characterization of organic solar cells fabricated by spin coating pure PFO–MEH–PPV, PECOD and their blend as the organic active layer onto indium tin oxide layer (150 nm), followed by the evaporation of silver cathode (110 nm). The current–voltage characteristics of these cells were determined and external quantum efficiency. Upon blending the two polymers in solid forms, it could be seen that the efficiency (6.25%) for the cells based on a blend layer is higher than the ones without blending (4.4%). Finally, we demonstrated here that the combination/blending of conjugated polymers has resulted in optimized solar device function, with reasonably quantum efficiency higher than 10%.

This paper describes spectroscopic evidence for the photoinduced transfer of a hole from the biexcitonic state of a CdS quantum dot (QD) to a phenothiazine (PTZ) molecular acceptor, covalently link...

The notable photophysical characteristics of perovskite quantum dots (PQDs) (CsPbBr3) are suitable for optoelectronic devices. However, the performance of PQDs is unstable because of their surface defects. One way to address the instability is to passivate PQDs using different organic (polymers, oligomers, and dendrimers) or inorganic (ZnS, PbS) materials. In this study, we performed steady-state spectroscopic investigations to measure the photoluminescence (PL), absorption (A), transmission (T), and reflectance (R) of perovskite quantum dots (CsPbBr3) and ethylene vinyl acetate/terpene phenol (1%) (EVA-TPR (1%), or EVA) copolymer/perovskite composites in thin films with a thickness of 352 ± 5 nm. EVA is highly transparent because of its large band gap, furthermore, it is inexpensive and easy to process. However, the compatibility between PQDs and EVA should be established, therefore, a series of analyses was performed to compute parameters, such as the band gap, the coefficients of absorbance and extinction, the index of refractivity, and the dielectric constant (real and imaginary parts), from the data obtained from the above investigation. Finally, the optical conductivities of the films were studied. All these analyses showed that the EVA/PQDs were more efficient and stable both physically and optically. Hence, EVA/PQDs could become copolymer/perovskite active materials suitable for optoelectronic devices, such as solar cells and perovskite/polymer light-emitting diodes (PPLEDs).

Tanneries create a serious threat to the environment by generating a significant amount of toxic metal-containing solid waste. This study deals with the application of bio-electrokinetic remediation (Bio-EK) of tannery effluent contaminated soil (TECS). Metagenomes representing the TECS sample were sequenced using the Illumina HiSeq platform. The bioreduction of hexavalent chromium Cr(VI)to trivalent chromium Cr (III) was achieved by BIO-EK techniques. NGS-data (Next Generation Sequencing) analysis was revealed that Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Planctomycetes were identified in the bio-electrokinetic system. Proteobacteria are responsible for the bioreduction of chromium hexavalent by the formation of FeS particles. The bio-generated FeS particles can be reduced the toxic chromium (VI) to non–toxic chromium (III) in soil. Simultaneously total chromium and organic content were significantly removed in BIO-EK (40 and 290 mg kg−1) when compared to control soil (182 and 240 mg kg−1). The presence of pollutant degrading microbes such as Desulfovibrio, Pseudomonas, Bacillus, Clostridium, Halanaerobium enhanced the bioreduction of the chromium during the electrokinetic remediation. This study can be claimed that the microbial cultures assisted electrokinetic remediation of total chromium, organic and iron in the tannery effluent contaminated soil was one of the suitable efficient techniques. In addition, the viability of the new combination technology developed (Electrokinetic + Bio) to treat low-permeability polluted soils was demonstrated.

A hybrid and straightforward nanosystem that can be used simultaneously for cancer-targeted fluorescence imaging and targeted drug delivery in vitro was reported in this study. A chitosan (CS) polymer coated with reduced graphene oxide (rGO) and implanted with Fe3O4 nanoparticles was fabricated. The fundamental physicochemical properties were confirmed via FT-IR, XRD, FE-SEM, HR-TEM, XPS, and VSM analysis. The in vivo toxicity study in zebrafish showed that the nanocomposite was not toxic. The in vitro drug loading amount was 0.448 mg/mL−1 for doxorubicin, an anticancer therapeutic, in the rGO/Fe3O4/CS nanocomposite. Furthermore, the pH-regulated release was observed using folic acid. Cellular uptake and multimodal imaging revealed the benefit of the folic acid-conjugated nanocomposite as a drug carrier, which remarkably improves the doxorubicin accumulation inside the cancer cells over-express folate receptors. The rGO/Fe3O4/CS nanocomposite showed enhanced antibiofilm and antioxidant properties compared to other materials. This study's outcomes support the use of the nanocomposite in targeted chemotherapy and the potential applications in the polymer, cosmetic, biomedical, and food industries.

In this study, we reported the biological approach to synthesis of ZnO nanorod (NR) on the reduced graphene oxide (RGO) for photocatalytic, antibacterial activity and hydrogen production under sunlight. Bacillus subtilis played a vital role in the production of biogenic ammonia from synthetic urine and utilized for the synthesis of ZnONR on the RGO sheet. The morphological study revealed that RGO sheets displayed a tremendous role in anchoring ZnONR. XRD patterns showed the ZnO crystal phase on the RGO sheets. XPS and Raman spectra confirmed that the bio-hydrothermal method as suitable for GO converted into RGO. The transient photocurrent and I/V measurement are exhibited as an increment on the RGO-ZnONR compared to ZnONR. The RGO-ZnONR composites showed excellent performance with decolorization of MB and textile dyes and efficient control of the E. coli and S. aureus. RGO-ZnONR exhibited remarkable noted as a higher photocatalytic hydrogen evolution rate (940 μmol/h/gcat) than the ZnONR (369.5 μmol/h/g cat). As a result of photocatalytic performance to correlate with sunlight intensity was extensively studied. RGO plays an essential role in interface electron transfer from sunlight to ZnONR for enhancing •OH radical formation to cleavage of dye color substance and eradicated bacterial cells.

Two-dimensional (2D) materials have gained prominent attention in the nano-electronics arena, owing to their tunable electronic and optical features. Here, the physical properties of a janus MoSSe monolayer are examined upon the chemically co-doping of S/Se sites by non-metallic and halogen elements (C, Si, N, P, As, and F) employing first-principles calculations. Accordingly, an alteration of both the upper valence and the lower conduction states is revealed for janus MoSSe monolayer upon the replacement of both S and Se anion host atoms by sp-elements (C, Si, N, P, As, and F). A shift in the lowest conduction band underneath the Fermi energy level (EF) occurs in janus MoSSe monolayer when both S and Se elements are replaced by (F, F) atoms. This effectively conducted to a system with an n-type character. In contrast, the highest valence bands moved upward EF owing to the co-doping effect of C, Si, N, P, and As atoms on the janus MoSSe monolayer with p-type nature. The key features of the optical spectra, such as the optical absorption, reflectivity, and electron loss functions of the co-doped janus MoSSe monolayer are inspected. Our results imply a modification in the low-energy photon regime of the co-doped janus MoSSe monolayer at S and Se host atoms by non-metallic sp-elements comparatively to the free-standing monolayer. A reduction in the optical absorption and an increase in the reflectivity at low-energy photon window are detected when the janus MoSSe monolayer is co-doped by (C, Si), (N, P), (P,As), and (F,F) elements, respectively at S and Se chalcogen atoms. The current study infers that the co-doping S and Se sites of janus MoSSe monolayers, with sp- elements, can be beneficial in the future applications of 2D materials for the field-effect transistors and nano-electronic devices.

Ba2&minus, xSrxZnWO6 double perovskite (DP) oxide compounds (x = 1, 1.25, 1.5, 1.75, 2) were successfully created by means of conventional solid-state techniques. The crystal structures of our series were studied using an X-ray diffractometer. The x = 1 compound has a cubic (Fm-3m) crystal structure, the 1 &le, x &le, 2 compounds have tetragonal (I4/m) symmetry, and the phase was transferred to monoclinic (P21/n) symmetry for the Sr2ZnWO6 (x = 2) compound. Scanning electron microscopy (SEM) was used to investigate the morphology of the series, showing that the samples had crystallized microstructures. Molecular bonds were investigated using Fourier transform infrared and Raman spectroscopies, which confirmed the double perovskite octahedral geometry for the samples in our series. Furthermore, the octahedral W&ndash, O6 anti-symmetric stretching mode was found to occur. The optical properties of the Ba2&minus, xSrxZnWO6 series were studied using Ultraviolet&ndash, visible (UV&ndash, vis) diffuse reflectance and photoluminescence (PL) spectroscopies. The absorption edge of the samples appeared around the near-violet and visible spectra, between 336&ndash, 360 nm. The band gap energy was investigated in two ways&mdash, using the absorption cutoff and Tauc plots&mdash, which increased from 3.52 to 3.7 eV with increasing substitution of Ba2+ by Sr2+. Furthermore, excitation and emission spectra were collected at room temperature. A broad band at 260&ndash, 360 nm appeared in the PLE spectra for all samples, and the PL spectra of the samples had a band that spread from 320&ndash, 450 nm.

Chemotherapy, the most commonly used therapeutic method for cancer, has the inherent constraint of low bioavailability. A number of physical cancer therapeutic treatments like radiation, ultrasound, photo-acoustic/photo thermal, microwave therapies are based on locating the afflicted sites with the help of imaging, but the serious drawbacks of these treatment options are that they damage the neighboring normal tissues and/or induce undesired cancer metastasis. In addition, these methods of treatment are very expensive and not in the reach of a common man especially in the developing countries. Therefore, innovative, less invasive and cost effective treatment methods with the help of less toxic drugs have been sought for treating cancer. In this work, photo-catalytic method of killing cancer cells, using the nanostructured silver loaded tungsten oxide (Ag/WO3) as photo-catalysts, in conjunction with broadband UV radiation is presented. Ag/WO3with two different mass ratios of Ag and WO3 (1% Ag/WO3 and 3% Ag/WO3) were synthesized, characterized and these nanostructured materials served as photo-catalysts in the process of killing cancer cells by photo-catalytic method. The advantage of loading Ag in WO3 is quite evident from the observed increase in the photo-catalytic killing of the HeLa cells. This photo-catalytic enhancement was effectively caused by the development of Schottky junction between Ag in WO3, which led to a substantial inhibition of photo-generated charge recombination and also by the stimulation of surface plasmon resonance in silver nanoparticles, which led to the enhanced visible light absorption by the material.

In this study, we compared different types of biomolecular markers in kidney cancer patients and in normal healthy controls, using fluorescence emission spectra and synchronous fluorescence excitation spectra. We were able to provide an accurate classification of the spectral features of kidney cancer patients relative to that of normal controls, in terms of the concentration ratios of biomolecules (viz., tryptophan, NADH, FAD, basic porphyrin, and acidic porphyrin) based on the intensity of their spectral peaks. The specificity and sensitivity of the method were 90%. The rationale of our current approach is to evolve an innovative protocol for the spectral characterization of in vitro optical analyses suitable for both small clinics and hospitals.

We examine superradiant (SR) light or amplified spontaneous emission (ASE) from a whispering-gallery-mode (WGM) laser comprising various sized (CdSe) ZnS quantum dots (QDs) in colloidal liquid. Laser-induced fluorescence (LIF) with a full width at half maximum (FWHM) of 40 nm is observed when the colloidal QD system is pumped with 2 mJ of laser light at 355 nm (3rd harmonic of Nd:YAG laser). Under optimal conditions of pump energy and focusing, ASE at 520 nm with a bandwidth of Δλ=8 nm (FWHM) and divergence of 9 mrad is observed. When the QDs are embedded on a high-Q factor silica microsphere ((functionalized with an amine), SMA), they generate WGMs with random peak distributions. Finally, when all the QDs embedded in SMAs are mixed and placed in a cuvette, we obtain a “WGM laser” that is almost continuously tunable from 520 nm to 630 nm with a spectral width less than 2 nm (FWHM) in the WGM and less than 1.2 nm in the cavity mode. We believe that this is the first report on a frequency tunable laser obtained using (CdSe) ZnS QDs embedded in an SMA, exhibiting an efficiency of 0.06%.

Hybrid nanocomposites can offer a wide range of opportunities to control the light-matter interac- tion and electromagnetic energy flow at the nanoscale, leading to exotic optoelectronic devices. We study theoretically the dipole-dipole interaction in noble metal nanoparticles-graphene nanodisks- quantum dots hybrid systems in the optical region of the electromagnetic spectrum. The quantum dot is assumed to be a three-level atom interacting with ultrashort control and probe pulses in a Lambda configuration. The dynamics of the system are studied by numerically solving for the time evo- lution of the density matrix elements. We investigate the rate of energy exchange between surface plasmon resonances of the graphene nanodisks and excitons of the quantum dots in the presence of metal nanoparticles at steady state and for specific geometrical conditions of the system. Ultrafast population dynamics are obtained with a large energy exchange rate significantly depending on the size of metal nanoparticles. The power transfer can be controlled by varying the center-to-center distances between the components of the system, and their positions with respect to each other. We also find that the rate of energy transfer within the system is governed by the probe field Rabi frequency, enhanced by the dipole-dipole interaction., Comment: 8 pages and 6 figures

Defects in the organic ligand layers on the surfaces of colloidal quantum dots (QDs) provide pathways for corrosive molecules to penetrate to the QD core. This paper describes the decrease in the p...

Colloidal semiconductor nanocrystals, or "quantum dots" (QDs), have several optical and chemical properties that give them the potential to enable nonincremental increases in the efficiencies of many types of photocatalytic reactions relevant for energy conversion and organic synthesis. Colloidal photocatalysts have many desirable characteristics of both heterogeneous and homogeneous catalysts but come with their own particular set of challenges. This viewpoint outlines some of the obstacles one first encounters when driving reactions with these colloids and offers some strategies for overcoming these obstacles, including ways to extend their excited state lifetimes, prevent corrosion by photogenerated holes, and choose a surface chemistry and buffering system for maximum colloidal stability over a range of environmental conditions.

In this report, a series of 3-(4-(Dimethylamino) phenyl)-1-(4,3 di-substituted phenyl)-(2E) - propen -1-one chalcones was synthesised and examined as optical materials. The influence of functional groups (FG) and solvents on their photophysical properties was investigated. These include absorption, fluorescence, Stokes shift, and amplified spontaneous emission (ASE). The absorption spectra of all compounds showed a wavelength band in the range 404–429 nm, whereas the fluorescence spectra exhibited a band at 470–535 nm. We found that the fluorescence intensity was inversely proportional to the concentration of chalcones. The FGs and solvents had an amazing effect on the photophysical properties of the synthesised materials. Unexpectedly, the electron withdrawing group showed a highly red shift, whereas the electron donating group exhibited a blue shift. Further, these compounds showed large Stokes shifts (up to 5800 cm−1). ASE was observed under pump pulse laser excitation, and the wavelengths were tuned from 509 to 566 nm.

This paper describes the use of electrostatic assemblies of negatively charged colloidal CuInS2/ZnS quantum dot (QD) sensitizers and positively charged, trimethylamino-functionalized iron tetraphenylporphyrin catalysts (FeTMA) to photoreduce CO2 to CO in water upon illumination with 450 nm light. This system achieves a turnover number (TON) of CO (per FeTMA) of 450 after 30 h of illumination, with a selectivity of 99%. Its sensitization efficiency (TON per Joule of photons absorbed) is a factor of 11 larger than the previous record for photosensitization of an iron porphyrin catalyst for this reaction, held by a system in which both QDs and metal porphyrin were uncharged. Steady-state and time-resolved optical spectroscopy provides evidence for electrostatic assembly of QDs and FeTMA. Control of the size of the assemblies with addition of a screening counterion, K+, and a correlation between their measured size and their catalytic activity, indicates that the enhancement in performance of this system over the analogous uncharged system is due to the proximity of the FeTMA catalyst to multiple light-absorbing QDs and the selective formation of QD-FeTMA contacts (rather than QD-QD or FeTMA-FeTMA contacts). This system therefore shows the ability to funnel photoinduced electrons to a reaction center, which is crucial for carrying out reactions that require multistep redox processes under low photon flux, and thus is an important advance in developing artificial photocatalytic systems that function in natural light.

In the present work, a visible light driven AgVO3/BiOI nanocomposite photocatalyst with different wt % (1, 2, 3) of AgVO3 was fabricated by using facile hydrothermal method. Further, the nanocomposite was characterized by FT-IR, XRD, SEM, TEM, EDS, UV–vis DRS, photoluminescence and photoelectrochemical studies. The structural characterization showed nanorods on nanosheet surface. Among different AgVO3 loaded samples, the photocatalytic efficiency of 1 wt % AgVO3/BiOI nanocomposite was found to be comparatively higher than the pure BiOI and AgVO3. The photodegradation rate constant values of pure BiOI, AgVO3 and 1, 2, 3 wt % AgVO3/BiOI nanocomposites are 0.006, 0.0033, 0.0255, 0.01575, 0.0116 min−1 respectively. This enhanced photocatalytic activity was due to the increasing visible light absorption ability and efficient separation of the charge carriers. Thereby, the 1 wt % AgVO3/BiOI nanocomposite photocatalyst exhibited increased photodegradation activity, photostability and recyclability characteristics. The radical trapping experiment confirmed the role of OH and h+ in the photocatalytic degradation of RhB. Based on this, the probable mechanism of degradation of RhB under visible light irradiation has also been proposed. Hence, we believe it could be a promising material that can be employed for the photodegradation of organic pollutants present in wastewater.

Cadmium and zinc are leading heavy metal pollutants causing serious health problems when discharged into the aquatic environments. The present investigation focused on the bioaccumulation of Cd2+ and Zn2+depending on the sorption process by Bacillus amyloliquefaciens HM28. The selected bacterium was multi-metal (Zn2+, Pb2+, Cd2+, Cu2+ and Li+) and antibiotic (cefotaxime, ampicilin, nalidixic acid, ceftazidime, penicillin and kanamycin) resistance was resolved. The identified strain showed maximum resistance onCd2+ (2575 ppm) and Zn2+ (1300 ppm). The sorption of Cd2+ and Zn2+ by a dried bacterium was investigated. Biosorption of Cd2+ was maximum (98.4 ± 5.2%) at 100 mg/L concentration and maximum Zn2+ (98.3 ± 1.5%) was detected in the medium containing 150 mg/L metal ion. Bioremoval was maximum after 30 min contact time with dried biomass and the absorption rate improved. The optimum Cd2+ and Zn2+ bioremoval yield of 93 ± 4.4% and 89.8 ± 4.3% were observed, at pH 7.0 and 7.5, respectively. Despite the significant reduction in growth rate, heavy metals increased nitro-blue tetrazolium reduction from 11 ± 1.3 to 67 ± 3.3%. Dehydrogenase activity elevated due to heavy metal stress. Bacterial biomass was immobilized in a glass column (20 cm × 2 cm). Biosorption of Cd2+ and Zn2+ ions were performed in a packed bed column. The breakthrough time of Cd2+ was 210 min at 1 mL/min flow rate and it decreased 94 min at 5 mL/min flow rate, whereas 240 min at 1 mL/min, and 90 min at 5 mL/min, respectively. The absorption capacity was 4.87 ± 0.8 to 5.43 ± 0.5 mg/g for Cd2+ and 3.85 ± 0.3 to 4.53 ± 0.4 mg/g for Zn2+. The present findings revealed the potential of B. amyloliquefaciens HM28 biomass in Cd2+ and Zn2+ biosorption, with feasibility in the bioremediation of Cd2+ and Zn2+ contaminated water.

Turbinaria ornata is brown marine macroalgae contains diverse bioactive components exhibiting various biomedical properties. This study intends to analyze the inhibitory effect of Hexadecanoic acid (HA) of T. ornata on HT-29 human colon cancer cells. The isolated compound were characterized using UV, FT-IR and GC–MS analysis respectively. The HA was treated in HT-29 human colon cancer lines and the cell growth inhibition was determined by MTT assay. The antioxidant effect of HA was evaluated by DPPH and Superoxide radical scavenging assay. The IC50 value of DPPH and Superoxide radical was 70.62 μg/ml and 71.41 μg/ml, respectively. Thus, in vitro anticancer activity of HA acts as potential cell growth inhibitor with IC50 value of 36.04 μg/ml. Apoptosis associated factors like apoptosis induction were observed by AO/EtBr staining, ROS formation was determined by 2′,7′–Dichlorodihydrofluorescein diacetate and cell distribution was analyzed by flow cytometry. HA exhibits 77.83% of apoptotic cells and increasing the fluorescence intensity in a concentration-dependent manner, which revealed ROS formation. Cell cycle analysis exposed that cells were inhibited in the G0/G1 phase. This study explored that HA may be potential anticancer materials in future.

Nanocrystalline nickel ferrite spinel, NiFe2O4, with average crystallite size of 23.98 and 19.76 nm were successfully synthesized under sol–gel method (SGM) and microwave method (MM) conditions without using any surfactant or otherwise structure-directing (oxalic acid as the fuel) agents. Powder x-ray diffraction, high-resolution scanning electron microscopies indicate that single-crystalline nanoparticles are well-dispersed in the nickel ferrite. The elemental investigation of nickel ferrite was attained from energy-dispersive x-ray (EDX) analysis. Their optical properties (diffuse reflectance spectroscopy and photoluminescence) were described in depth in relative with their structural characteristics and the functionalization performance. After the magnetic measurements, samples showed a ferromagnetic behavior and the magnetization (Ms) value of NiFe2O4-MM is higher, i.e., 59.33 emu/g than NiFe2O4-SGM (50.12 emu/g). The magnetic properties could be further changed by controlling the shape, size, and crystallinity of the nanocrystals. Determination of concentration NiFe2O4 ions’ average number of atoms per nanoparticle was calculated by the new method as follows. Consequently, the designated procedure improves catalytic activity of nickel ferrite powders in aerobic oxidation of benzyl alcohol and catalytic reactions.

Photosensitization of molecular catalysts to reduce CO2 to CO is a sustainable route to storable solar fuels. Crucial to the sensitization process is highly efficient transfer of redox equivalents from sensitizer to catalyst; in systems with molecular sensitizers, this transfer is often slow because it is gated by diffusion-limited collisions between sensitizer and catalyst. This article describes the photosensitization of a meso-tetraphenylporphyrin iron(III) chloride (FeTPP) catalyst by colloidal, heavy metal-free CuInS2/ZnS quantum dots (QDs) to reduce CO2 to CO using 450 nm light. The sensitization efficiency (turnover number per absorbed unit of photon energy) of the QD system is a factor of 18 greater than that of an analogous system with a fac-tris(2-phenylpyridine)iridium sensitizer. This high efficiency originates in ultrafast electron transfer between the QD and FeTPP, enabled by formation of QD/FeTPP complexes. Optical spectroscopy reveals that the electron-transfer processes primarily responsi...