Synergistic influence of iodine and hydrogen peroxide towards the degradation of harmful algal bloom of Microcystis aeruginosa.

Cyanobacterial blooming due to the influence of temperature and increased nutrients in ponds/lakes aided by the runoff from agricultural lands, is a serious environmental issue. The presence of cyanotoxins in water may poison the health of aquatic organisms, animals, and humans. In this study, we focus on chemical assisted degradation of Microcystis aeruginosa- an alga that is of special relevance owing to its consistent blooming, especially in tropical regions. The study aims to ascertain the individual iodine (I) and hydrogen peroxide (H2O2) and their combination (hereinafter referred to as IH) effects on the degradation of Microcystis aeruginosa. As expected, the collected pond water revealed the presence of metal ions viz., Ni, Zn, Pb, Cu and Mn, which enriched the blooming of M. aeruginosa. Interestingly, a complete rupture of the cells - pigment loss, biochemical degradation and oxidative damage-was observed by the IH solution after exposure for ∼9 h under ambient conditions. In comparison to control (original water without chemicals), the addition IH completely eliminated the pigments phycocyanin (99.5%) and allophycocyanin (98%), and degraded ∼81% and 91% of carbohydrates and proteins, respectively due to the synergistic action of I and H. Superior degradation of algae through a simple and eco-friendly approach presented in this study could be explored more effectively towards its large-scale applicability.

Biofunctionalized CdS Quantum Dots: A Case Study on Nanomaterial Toxicity in the Photocatalytic Wastewater Treatment Process.

The toxic nature of inorganic nanostructured materials as photocatalysts is often not accounted for in traditional wastewater treatment reactions. Particularly, some inorganic nanomaterials employed as photocatalysts may release secondary pollutants in the form of ionic species that leach out due to photocorrosion. In this context, this work is a proof-of-concept study for exploring the environmental toxicity effect of extremely small-sized nanoparticles (<10 nm) like quantum dots (QDs) that are employed as photocatalysts, and in this study, cadmium sulfide (CdS) QDs are chosen. Typically, CdS is an excellent semiconductor with suitable bandgap and band-edge positions that is attractive for applications in solar cells, photocatalysis, and bioimaging. However, the leaching of toxic cadmium (Cd2+) metal ions due to the poor photocorrosion stability of CdS is a matter of serious concern. Therefore, in this report, a cost-effective strategy is devised for biofunctionalizing the active surface of CdS QDs by employing tea leaf extract, which is expected to hinder photocorrosion and prevent the leaching of toxic Cd2+ ions. The coating of tea leaf moieties (chlorophyll and polyphenol) over the CdS QDs (referred to hereafter as G-CdS QDs) was confirmed through structural, morphological, and chemical analysis. Moreover, the enhanced visible-light absorption and emission intensity of G-CdS QDs in comparison to that of C-CdS QDs synthesized through a conventional chemical synthesis approach confirmed the presence of chlorophyll/polyphenol coating. Interestingly, the polyphenol/chlorophyll molecules formed a heterojunction with CdS QDs and enabled the G-CdS QDs to exhibit enhanced photocatalytic activity in the degradation of methylene blue dye molecules over C-CdS QDs while effectively preventing photocorrosion as confirmed from cyclic photodegradation studies. Furthermore, detailed toxicity studies were conducted by exposing zebrafish embryos to the as-synthesized CdS QDs for 72 h. Surprisingly, the survival rate of the zebrafish embryos exposed to G-CdS QDs was equal to that of the control, indicating a significant reduction in the leaching of Cd2+ ions from G-CdS QDs in comparison to C-CdS QDs. The chemical environment of C-CdS and G-CdS before and after the photocatalysis reaction was examined by X-ray photoelectron spectroscopy. These experimental findings prove that biocompatibility and toxicity could be controlled by simply adding tea leaf extract during the synthesis of nanostructured materials, and revisiting green synthesis techniques can be beneficial. Furthermore, repurposing the discarded tea leaves may not only facilitate the control of toxicity of inorganic nanostructured materials but can also help in enhancing global environmental sustainability.

Facile Synthesis of Gram-Scale Mesoporous Ag/TiO2 Photocatalysts for Pharmaceutical Water Pollutant Removal and Green Hydrogen Generation.

This work demonstrates a two-step gram-scale synthesis of presynthesized silver (Ag) nanoparticles impregnated with mesoporous TiO2 and evaluates their feasibility for wastewater treatment and hydrogen gas generation under natural sunlight. Paracetamol was chosen as the model pharmaceutical pollutant for evaluating photocatalytic performance. A systematic material analysis (morphology, chemical environment, optical bandgap energy) of the Ag/TiO2 photocatalyst powder was carried out, and the influence of material properties on the performance is discussed in detail. The experimental results showed that the decoration of anatase TiO2 nanoparticles (size between 80 and 100 nm) with 5 nm Ag nanoparticles (1 wt %) induced visible-light absorption and enhanced charge carrier separation. As a result, 0.01 g/L Ag/TiO2 effectively removed 99% of 0.01 g/L paracetamol in 120 min and exhibited 60% higher photocatalytic removal than pristine TiO2. Alongside paracetamol degradation, Ag/TiO2 led to the generation of 1729 µmol H2 g-1 h-1. This proof-of-concept approach for tandem pollutant degradation and hydrogen generation was further evaluated with rare earth metal (lanthanum)- and nonmetal (nitrogen)-doped TiO2, which also showed a positive response. Using a combination of ab initio calculations and our new theory model, we revealed that the enhanced photocatalytic performance of Ag/TiO2 was due to the surface Fermi-level change of TiO2 and lowered surface reaction energy barrier for water pollutant oxidation. This work opens new opportunities for exploiting tandem photocatalytic routes beyond water splitting and understanding the simultaneous reactions in metal-doped metal oxide photocatalyst systems under natural sunlight.

Priming with Nanoscale Materials for Boosting Abiotic Stress Tolerance in Crop Plants.

Seed priming is a cost-effective, practical, environmental, and farmer-friendly method to improve seed germination that can potentially increase the growth and yield of plants. The priming process enhances various physiological and biochemical mechanisms of defense and empowers the seeds or seedlings to overcome different environmental stresses. However, under critical circumstances, plants are hindered from absorbing specific chemical priming reagents owing to their larger size, molecular structure, or lack of carriers. Therefore, nanoscale materials having exceptional physiochemical properties and a large surface/volume ratio are expected to be better absorbed by the seeds/seedlings as priming agents in comparison to bulk chemicals and can trigger enhanced molecular interactions at the cellular level. Further, the flexibility in altering the surface chemical properties of the nanomaterials can facilitate better interaction with the seeds/seedlings while inhibiting the wastage of priming agents. In this review, we have systematically discussed the potentiality of various nanostructured materials as priming agents in alleviating the adverse effects of various abiotic stresses, viz., drought, salinity, high temperature, cold temperature, and heavy metals, by studying the growth parameters and physiological and biochemical response of various crop plants subjected to these stress conditions. Also, we have highlighted the molecular mechanism and activation of genes involved in enabling abiotic stress tolerance in plants after being primed with nanostructured materials.

A review on nanostructured silver as a basic ingredient in medicine: physicochemical parameters and characterization.

Recent studies with silver nanoparticles (AgNPs) and the history of silver metal as a broad-spectrum bactericidal and virucidal agent, places silver as one of the future biocidal candidates in the field of nanomedicine to eliminate bacteria and viruses, especially multidrug resistant ones. In this review, we have described the various morphologies of AgNPs and correlated the enhanced bactericidal activity with their prominent {111} facets. In addition to prioritizing the characterization we have also discussed the importance of quantifying AgNPs and silver ion content (Ag+) and their different mechanisms at the chemical, biological, pharmacological, and toxicological levels. The mechanism of action of AgNPs against various bacteria and viruses including the SARS-CoV-2 was analyzed in order to understand its effectiveness as an antimicrobial agent with therapeutic efficacy and low toxicity. Further, there is the need to characterize AgNPs and quantify the content of free Ag+ for the implementation of new systematic studies of this promising agent in nanomedicine and in clinical practice.

Sequential screening for lung cancer in a high-risk group: randomised controlled trial: LungSEARCH: a randomised controlled trial of Surveillance using sputum and imaging for the EARly detection of lung Cancer in a High-risk group.

BACKGROUND: Low-dose computed tomography (LDCT) screening detects early-stage lung cancer and reduces mortality. We proposed a sequential approach targeted to a high-risk group as a potentially efficient screening strategy. METHODS: LungSEARCH was a national multicentre randomised trial. Current/ex-smokers with mild/moderate chronic obstructive pulmonary disease (COPD) were allocated (1:1) to have 5 years surveillance or not. Screened participants provided annual sputum samples for cytology and cytometry, and if abnormal were offered annual LDCT and autofluorescence bronchoscopy (AFB). Those with normal sputum provided annual samples. The primary end-point was the percentage of lung cancers diagnosed at stage I/II (nonsmall cell) or limited disease (small cell). RESULTS: 1568 participants were randomised during 2007-2011 from 10 UK centres. 85.2% of those screened provided an adequate baseline sputum sample. There were 42 lung cancers among 785 screened individuals and 36 lung cancers among 783 controls. 54.8% (23 out of 42) of screened individuals versus 45.2% (14 out of 31) of controls with known staging were diagnosed with early-stage disease (one-sided p=0.24). Relative risk was 1.21 (95% CI 0.75-1.95) or 0.82 (95% CI 0.52-1.31) for early-stage or advanced cancers, respectively. Overall sensitivity for sputum (in those randomised to surveillance) was low (40.5%) with a cumulative false-positive rate (FPR) of 32.8%. 55% of cancers had normal sputum results throughout. Among sputum-positive individuals who had AFB, sensitivity was 45.5% and cumulative FPR was 39.5%; the corresponding measures for those who had LDCT were 100% and 16.1%, respectively. CONCLUSIONS: Our sequential strategy, using sputum cytology/cytometry to select high-risk individuals for AFB and LDCT, did not lead to a clear stage shift and did not improve the efficiency of lung cancer screening.

Eliminated Phototoxicity of TiO2 Particles by an Atomic-Layer-Deposited Al2 O3 Coating Layer for UV-Protection Applications.

We demonstrate the conformal coating of an ultrathin Al2 O3 layer on TiO2 nanoparticles through atomic layer deposition by using a specifically designed rotary reactor to eliminate the phototoxicity of the particles for cosmetic use. The ALD reactor is modified to improve the coating efficiency as well as the agitation of the particles for conformal coating. Elemental and microstructural analyses show that ultrathin Al2 O3 layers are conformally deposited on the TiO2 nanoparticles with a controlled thickness. Rhodamine B dye molecules on Al2 O3 -coated TiO2 exhibited a long life time under UV irradiation, that is, more than 2 h, compared to that on bare TiO2 , that is, 8 min, indicating mitigation of photocatalytic activity by the coated layer. The effect of carbon impurities in the film resulting from various deposition temperatures and thicknesses of the Al2 O3 layer on the photocatalytic activity are also thoroughly investigated with controlled experimental condition by using dye molecules on the surface. Our results reveal that an increased carbon impurity resulting from a low processing temperature provides a charge conduction path and generates reactive oxygen species causing the degradation of dye molecule. A thin coated layer, that is, less than 3 nm, also induced the tunneling of electrons and holes to the surface, hence oxidizing dye molecules. Furthermore, the introduction of an Al2 O3 layer on TiO2 improves the light trapping thus, enhances the UV absorption.

Superior Photostability and Photocatalytic Activity of ZnO Nanoparticles Coated with Ultrathin TiO2 Layers through Atomic-Layer Deposition.

Atomic-layer deposition (ALD) is a thin-film growth technology that allows for conformal growth of thin films with atomic-level control over their thickness. Although ALD is successful in the semiconductor manufacturing industry, its feasibility for nanoparticle coating has been less explored. Herein, the ALD coating of TiO2 layers on ZnO nanoparticles by employing a specialized rotary reactor is demonstrated. The photocatalytic activity and photostability of ZnO nanoparticles coated with TiO2 layers by ALD and chemical methods were examined by the photodegradation of Rhodamine B dye under UV irradiation. Even though the photocatalytic activity of the presynthesized ZnO nanoparticles is higher than that of commercial P25 TiO2 nanoparticles, their activity tends to decline due to severe photocorrosion. The chemically synthesized TiO2 coating layer on ZnO resulted in severely declined photoactivity despite the improved photostability. However, ultrathin and conformal ALD TiO2 coatings (≈ 0.75-1.5 nm) on ZnO improved its photostability without degradation of photocatalytic activity. Surprisingly, the photostability is comparable to that of pure TiO2, and the photocatalytic activity to that of pure ZnO.

Silver quantum cluster (ag9 )-grafted graphitic carbon nitride nanosheets for photocatalytic hydrogen generation and dye degradation.

We report the visible-light photocatalytic properties of a composite system consisting of silver quantum clusters [Ag9 (H2 MSA)7 ] (H2 MSA=mercaptosuccinic acid) embedded on graphitic carbon nitride nanosheets (AgQCs-GCN). The composites were prepared through a simple chemical route; their structural, chemical, morphological, and optical properties were characterized by using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, transmission electron microscopy, UV/Vis diffuse reflectance spectroscopy, and photoluminescence spectroscopy. Embedment of [Ag9 (H2 MSA)7 ] on graphitic carbon nitride nanosheets (GCN) resulted in extended visible-light absorption through multiple single-electron transitions in Ag quantum clusters and an effective electronic structure for hydroxyl radical generation, which enabled increased activity in the photocatalytic degradation of methylene blue and methyl orange dye molecules compared with pristine GCN and silver nanoparticle-grafted GCN (AgNPs-GCN). Similarly, the amount of hydrogen generated by using AgQCs-GCN was 1.7 times higher than pristine GCN. However, the rate of hydrogen generated using AgQCs-GCN was slightly less than that of AgNPs-GCN because of surface hydroxyl radical formation. The plausible photocatalytic processes are discussed in detail.

Anemia and performance status as prognostic markers in acute hypercapnic respiratory failure due to chronic obstructive pulmonary disease.

BACKGROUND: In patients with acute hypercapnic respiratory failure (AHRF) during exacerbations of COPD, mortality can be high despite noninvasive ventilation (NIV). For some, AHRF is terminal and NIV is inappropriate. However there is no definitive method of identifying patients who are unlikely to survive. The aim of this study was to identify factors associated with inpatient mortality from AHRF with respiratory acidosis due to COPD. METHODS: COPD patients presenting with AHRF and who were treated with NIV were studied prospectively. The forced expiratory volume in 1 second (FEV1), World Health Organization performance status (WHO-PS), clinical observations, a composite physiological score (Early Warning Score), routine hematology and biochemistry, and arterial blood gases prior to commencing NIV, were recorded. RESULTS: In total, 65 patients were included for study, 29 males and 36 females, with a mean age of 71 ± 10.5 years. Inpatient mortality in the group was 33.8%. Mortality at 30 days and 12 months after admission were 38.5% and 58.5%, respectively. On univariate analysis, the variables associated with inpatient death were: WHO-PS ≥ 3, long-term oxygen therapy, anemia, diastolic blood pressure < 70 mmHg, Early Warning Score ≥ 3, severe acidosis (pH < 7.20), and serum albumin < 35 g/L. On multivariate analysis, only anemia and WHO-PS ≥ 3 were significant. The presence of both predicted 68% of inpatient deaths, with a specificity of 98%. CONCLUSION: WHO-PS ≥ 3 and anemia are prognostic factors in AHRF with respiratory acidosis due to COPD. A combination of the two provides a simple method of identifying patients unlikely to benefit from NIV.