Transition metal ion (Ni2+, Cu2+ and Zn2+) doped defect pyrochlore, KTaTeO6: Synthesis, characterization and photocatalytic studies

One of the strategies to decrease the bandgap energy and increase the optical absorption ofthe catalysts is to dope with transition metal ions. In this paper, the results obtained for thedegradation of methylene blue (MB) pollutant in the presence of M2+ (M = Ni, Cu, and Zn) doped KTaTeO6 (here after abbreviated as M-KTTO) upon visible light irradiation are presented.The parent KTaTeO6 and the M2+ (M = Ni, Cu, and Zn) doped KTaTeO6 were prepared by solidstate and ion-exchange methods, respectively. All the samples were characterized by XRD,SEM/EDX, FT-IR, UV-Vis DRS, XPS, and PL techniques. The metal ion doping in place of K+has influenced the electronic and optical properties considerably. The doping of M2+ into KTTOlattice has narrowed the bandgap energy, increased the visible light absorbance leading to higherphotocatalytic activity. The M-KTTO materials show higher photocatalytic activity compared toparent KTTO, in particularly Cu-KTTO. The scavenging experiments indicate that •OH radicalsare the main active species involved in the photodegradation of MB. The Cu-KTTO ischemically stable and can be used at least up to five cycles. The mechanistic pathway of MBdegradation was proposed over Cu-KTTO

Synthesis, characterization and photocatalytic dye degradation studies of novel defect pyrochlore, KHf0.5Te1.5O6

We report the solid-state synthesis of KHf0.5Te1.5O6 (KHTO), its characterization and employment as photocatalyst for methylene blue and methyl violet degradations in aqueous solution. The material was subjected to X-ray Diffraction (XRD), Field emission-scanning electron microscopy (FE-SEM), Energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), N2 adsorption/desorption and XPS measurements. The material was crystallized in a cubic lattice with the   space group. The bandgap energy of the KHTO is 2.60 eV. The photocatalytic methylene blue (MB) and methyl violet (MV) dyes degradation efficiency of KHTO was investigated under the visible light irradiation. The mechanistic dye degradation pathway of MB was studied. The radical quenching experiments reveal that the short-lived species O2●-, OH●, and h+ actively participate in the degradation of MV and MB dyes. An additional terephthalic acid experiment was carried out to establish the participation of OH● radicals in the dye degradation process. The stability and reusability of the KHTO catalyst were also studied

Synthesis, characterization and photocatalytic dye degradation studies of novel defect pyrochlore, KHf0.5Te1.5O6

1092-1099In this study, KHf0.5Te1.5O6 (KHTO) semiconductor has been synthesized by the solid-state method. The synthesized material is characterized using X-ray diffraction, Fourier transform infrared spectroscopy, UV-visible diffuse reflectance spectroscopy, field emission-scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy and N2 adsorption/desorption measurements. The material is found to be crystallized in a cubic lattice with the space group Fdm . The bandgap energy of the KHTO is 2.6 eV. The photocatalytic activity of KHTO has been investigated by measuring the degradation of methylene blue (MB) and methyl violet (MV) dyes under the visible light irradiation. The mechanistic dye degradation pathway of MB has been studied. The radical quenching experiments reveal that the short-lived species O2●-, OH●, and h+ actively participate in the degradation of MB and MV dyes. An additional terephthalic acid experiment has been carried out to establish the participation of OH● radicals in the dye degradation. The stability and reusability of the KHTO catalyst are also studied

Autonomic Function following Acute Organophosphorus Poisoning: A Cohort Study

Autonomic dysfunction after chronic low level exposure to organophosphorus (OP) pesticides has been consistently reported in the literature, but not following a single acute overdose. In order to study autonomic function after an acute OP overdose, sixty-six overdose patients were compared to 70 matched controls. Assessment of autonomic function was done by heart rate response to standing, deep breathing (HR-DB) and Valsalva manoeuvre; blood pressure (BP) response to standing and sustained hand grip; amplitude and latency of sympathetic skin response (SSR); pupil size and post-void urine volume. The patients were assessed one and six weeks after the exposure. The number of patients who showed abnormal autonomic function compared to standard cut-off values did not show statistically significantly difference from that of controls by Chi-Square test. When compared to the controls at one week the only significant differences consistent with autonomic dysfunction were change of diastolic BP 3 min after standing, HR-DB, SSR-Amplitude, SSR-Latency, post-void urine volume and size of the pupil. At 6 weeks significant recovery of autonomic function was observed and only HR-DB was decreased to a minor degree, −5 beats/min [95%CI 2–8]. This study provides good evidence for the lack of long term autonomic dysfunction following acute exposure to OP pesticides

Effects of Deliberate Ingestion of Organophosphate or Paraquat on Brain Stem Auditory-Evoked Potentials

Organophosphate (OP) and paraquat (PQ) ingestion is a serious health problem. A common pathology behind OP or PQ poisoning is the generation of reactive oxygen species (ROS) which is known to cause ototoxicity. The aim of the study was to identify the effects of deliberate ingestion of OP or PQ on brain stem auditory-evoked potentials (BAEPs). Consecutive patients with deliberate self-poisoning with OP or PQ who were admitted to a secondary and a tertiary care hospital in the Southern province of Sri Lanka and matched controls were recruited. BAEPs were performed at 1 week (first assessment) and 6 weeks (second assessment) after the exposure. Interpeak latencies of I–III, III–V, and I–V were measured. There were 70 and 28 patients in the OP and PQ arms with the mean age of 32 ± 12 and 29 ± 12 years, respectively. There were 70 controls and their mean age was 33 ± 12 years. In OP and PQ poisoning, 53/70 and 18/28 came for the second assessment, respectively. The interpeak latency was not statistically different in the controls vs the first assessment, controls vs the second assessment, and the first vs the second assessment. There were no significant lesions in the auditory pathway in OP or PQ poisoned patients. The generation of ROS within the perilymphatic space following the ingestion of OP or PQ may not be sufficient to cause lesions in the auditory pathway. Further studies with the assessment of auditory threshold are needed

ADEPT: Detection and Identification of Correlated Attack Stages in IoT Networks

10.1109/JIOT.2021.3055937IEEE Internet of Things Journal886591660

Transition metal ion (Ni2+, Cu2+ and Zn2+) doped defect pyrochlore, KTaTeO6: Synthesis, characterization and photocatalytic studies

812-823One of the strategies to decrease the bandgap energy and increase the optical absorption of the catalysts is to dope with transition metal ions. In this paper, the results obtained for the degradation of methylene blue (MB) pollutant in the presence of M2+ (M = Ni, Cu, and Zn) doped KTaTeO6 (M-KTTO) upon visible light irradiation are presented. The parent KTaTeO6 and the M-KTaTeO6 were prepared by solid-state and ion-exchange methods, respectively. All the samples were characterized by XRD, SEM/EDX, FT-IR, UV-vis DRS, XPS, and PL techniques. The metal ion doping in place of K+ has influenced the electronic and optical properties considerably. The doping of M2+ into KTTO lattice has narrowed the bandgap energy, increased the visible light absorbance leading to higher photocatalytic activity. The M-KTTO materials show higher photocatalytic activity compared to parent KTTO, particularly Cu-KTTO. The scavenging experiments indicate that •OH radicals are the main active species involved in the photodegradation of MB. The Cu-KTTO is chemically stable and can be used for at least up to five cycles. The mechanistic pathway of MB degradation was proposed over Cu-KTTO

Linking plant traits to ecosystem service provision through a management gradient in a tropical dry forest

The exploitation of pristine forests decreases their functional diversity and ecosystem service provision. The forest management strategies of some rural societies, though, can increase the provision of specific ecosystem services useful to the community. This is tightly linked to shifts in forest functional traits, but few studies have investigated the changes to multiple provisioning, cultural and regulating ecosystem services across a traditional forest management gradient. This can give insights into the role of traditional management systems in the conservation of ecosystem services. Here we used a plot network of 60 tropical dry forest plots in Sri Lanka to test whether different forest management intensities are linked to differences in forest functional traits and ecosystem service provision through different tree size classes. Furthermore, we investigated the link between functional traits and ecosystem service provision with both redundancy analysis and linear mixed models. We found that the most intensely managed forest plots had some early successional traits such as light wood, small seeds and large leaves but, unexpectedly, taller trees than the least intensely managed plots. The intensely and moderately managed plots had a greater abundance of species delivering cultural and provisioning services than the least managed plots. We found significant links between the provision of construction services and mean tree height, and the delivery of cultural services and wood density. The links between functional traits and ecosystem services were clearest for individuals smaller than 10 cm DBH. Overall, the forest use and management by this rural community increased ecosystem provisioning services. For the first time we have characterised different links between species’ functional traits and the ecosystem services they provide in a tropical dry forest. We highlight that the differences across forest management intensities were clearest for trees in the smaller cohorts, which are generally ignored by many researches. Similar studies will identify relevant functional traits that will help discover new species providing key ecosystem services. Understanding the interactions between rural societies and the forests they manage will foster the creation of guidelines for sustainably enhancing forest cultural and provisioning services

Dense and strong, but superinsulating silica aerogel

Silica aerogel is the ultimate thermal insulator thanks to its record-breaking low thermal conductivity (λ), open porosity and hydrophobicity. Silica aerogel's thermal conductivity is lowest at intermediate densities (ρ ≈ 0.11 g/cm ) and, because of the strong, power-law dependence of the E modulus on density, this rather low density so far led to low E moduli. Even with polymer reinforcement, increasing stiffness is only possible at higher density, thus higher conductivity. This paper explores the synthesis of silica aerogel granules using ambient pressure drying to provide enhanced mechanical stiffness whilst maintaining thermal conductivities well below 20 mW m K . The aging and drying conditions affect the interplay between mechanical and thermal properties, and are varied to optimize the physical properties. The dense (ρ≤0.29 g/cm ), but superinsulating (λ≈15 mW m K ) silica aerogels presented in this paper challenge the community's understanding of heat transport in aerogels, and do not rely on polymer reinforcement. The underlying microscopic structural parameters affecting the mechanical and thermal transport properties are investigated by modelling and simulation of the aerogel back-bone. Short aging times reduce the cross-section of, and heat transport through, inter-particle necks, leading to an overall decrease in thermal conductivity through the solid skeleton (λ ). In addition, short-aged gels undergo a partial pore collapse during ambient pressure drying of the pore fluid due to less aged, hence weaker network structures. The resulting denser structure contains additional point contacts that increase stiffness, by up to an order of magnitude. However, heat transport through these newly formed point-contacts is limited and the gas phase conduction (λ ) is further suppressed due to the even smaller pore sizes. Strong and superinsulating particles are ideal fillers for aerogel composites, concrete and renders. The optimized APD aerogels, available as granules, are finally compiled in a composite thermal insulation board with an effective thermal conductivity down to 20 mW m K with improved strength: a 2-fold increase for E, compared to a board produced from classical silica aerogel granulate. The possibility to improve mechanical properties of pure silica aerogels can help aerogels to break into new high-strength, superinsulating structural applications needed to reduce carbon emissions of the built environment.ISSN:1359-645