Quantifying ecosystem carbon fluxes and stocks is essential for better understanding the global carbon cycle and improving projections of the carbon-climate feedbacks. Remote sensing has played a ...vital role in this endeavor during the last five decades by quantifying carbon fluxes and stocks. The availability of satellite observations of the land surface since the 1970s, particularly the early 1980s, has made it feasible to quantify ecosystem carbon fluxes and stocks at regional to global scales. Here we provide a review of the advances in remote sensing of the terrestrial carbon cycle from the early 1970s to present. First, we present an overview of the terrestrial carbon cycle and remote sensing of carbon fluxes and stocks. Remote sensing data acquired in a broad wavelength range (visible, infrared, and microwave) of the electromagnetic spectrum have been used to estimate carbon fluxes and/or stocks. Second, we provide a historical overview of the key milestones in remote sensing of the terrestrial carbon cycle. Third, we review the platforms/sensors, methods, findings, and challenges in remote sensing of carbon fluxes. The remote sensing data and techniques used to quantify carbon fluxes include vegetation indices, light use efficiency models, terrestrial biosphere models, data-driven (or machine learning) approaches, solar-induced chlorophyll fluorescence (SIF), land surface temperature, and atmospheric inversions. Fourth, we review the platforms/sensors, methods, findings, and challenges in passive optical, microwave, and lidar remote sensing of biomass carbon stocks as well as remote sensing of soil organic carbon. Fifth, we review the progresses in remote sensing of disturbance impacts on the carbon cycle. Sixth, we also discuss the uncertainty and validation of the resulting carbon flux and stock estimates. Finally, we offer a forward-looking perspective and insights for future research and directions in remote sensing of the terrestrial carbon cycle. Remote sensing is anticipated to play an increasingly important role in carbon cycling studies in the future. This comprehensive and insightful review on 50 years of remote sensing of the terrestrial carbon cycle is timely and valuable and can benefit scientists in various research communities (e.g., carbon cycle, remote sensing, climate change, ecology) and inform ecosystem and carbon management, carbon-climate projections, and climate policymaking.
•We review 50 years of history and advances in remote sensing of C fluxes and stocks•We present an overview of terrestrial C cycle, remote sensing, and key milestones•We review remote sensing platforms/sensors, data, methods, findings, and challenges•We also discuss the uncertainty and validation of the C flux and stock estimates•A forward-looking perspective and insights for future research are provided
•the rapid rise and decline of admissions and decreased severity of COVID-19 disease•compares 466 patients in the Omicron wave to 3962 patients in previous waves•describes disease severity of all ...admitted patients at peak bed occupancy•a lower mortality rate from Omicron compared to previous waves
The coronavirus disease 2019 (COVID-19) first reported in Wuhan, China in December 2019 is a global pandemic that is threatening the health and wellbeing of people worldwide. To date there have been more than 274 million reported cases and 5.3 million deaths. The Omicron variant first documented in the City of Tshwane, Gauteng Province, South Africa on 9 November 2021 led to exponential increases in cases and a sharp rise in hospital admissions. The clinical profile of patients admitted at a large hospital in Tshwane is compared with previous waves.
466 hospital COVID-19 admissions since 14 November 2021 were compared to 3962 admissions since 4 May 2020, prior to the Omicron outbreak. Ninety-eight patient records at peak bed occupancy during the outbreak were reviewed for primary indication for admission, clinical severity, oxygen supplementation level, vaccination and prior COVID-19 infection. Provincial and city-wide daily cases and reported deaths, hospital admissions and excess deaths data were sourced from the National Institute for Communicable Diseases, the National Department of Health and the South African Medical Research Council.
For the Omicron and previous waves, deaths and ICU admissions were 4.5% vs 21.3% (p<0.00001), and 1% vs 4.3% (p<0.00001) respectively; length of stay was 4.0 days vs 8.8 days; and mean age was 39 years vs 49,8 years.
Admissions in the Omicron wave peaked and declined rapidly with peak bed occupancy at 51% of the highest previous peak during the Delta wave.
Sixty two (63%) patients in COVID-19 wards had incidental COVID-19 following a positive SARS-CoV-2 PCR test . Only one third (36) had COVID-19 pneumonia, of which 72% had mild to moderate disease. The remaining 28% required high care or ICU admission. Fewer than half (45%) of patients in COVID-19 wards required oxygen supplementation compared to 99.5% in the first wave. The death rate in the face of an exponential increase in cases during the Omicron wave at the city and provincial levels shows a decoupling of cases and deaths
compared to previous waves, corroborating the clinical findings of decreased severity of disease seen in patients admitted to the Steve Biko Academic Hospital.
There was decreased severity of COVID-19 disease in the Omicron-driven fourth wave in the City of Tshwane, its first global epicentre.
Industrial wastewaters contain hazardous contaminants that pollute the environment and cause socioeconomic problems, thus demanding the employment of effective remediation procedures such as ...photocatalysis. Zinc oxide (ZnO) nanomaterials have emerged to be a promising photocatalyst for the removal of pollutants in wastewater owing to their excellent and attractive characteristics. The dynamic tunable features of ZnO allow a wide range of functionalization for enhanced photocatalytic efficiency. The current review summarizes the recent advances in the fabrication, modification, and industrial application of ZnO photocatalyst based on the analysis of the latest studies, including the following aspects: (1) overview on the properties, structures, and features of ZnO, (2) employment of dopants, heterojunction, and immobilization techniques for improved photodegradation performance, (3) applicability of suspended and immobilized photocatalytic systems, (4) application of ZnO hybrids for the removal of various types of hazardous pollutants from different wastewater sources in industries, and (5) potential of bio-inspired ZnO hybrid nanomaterials for photocatalytic applications using renewable and biodegradable resources for greener photocatalytic technologies. In addition, the knowledge gap in this field of work is also highlighted.
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•Recent insights on strategies to improve the efficacy of ZnO photocatalysts.•Application of ZnO hybrids in removing various types of pollutants in industries.•Comparison of suspended and immobilized photocatalytic systems and its applicability.•Synergy of bio-inspired ZnO photocatalysts and biopolymers for greener technologies.
Solid particle erosion experiments have been conducted to study the erosion behavior of multiple graphene-based coatings. In this paper, the effects of three factors on the erosion resistance have ...been investigated: (1) The effect of using graphene-based coatings (2) The effect of using single and multilayer coatings with alternating graphene and polyurethane layers, (3) The effects of angles of attack and erosion duration on the single and multilayer graphene coatings. The investigation also explored the coating surface quality, adhesion, and coating hardness. Finally, two parameters were used to evaluate the efficiency of the coating systems: Material removal and the depth of the erosion scar. It has been found that a single layer of graphene coating, H-146, provided the highest erosion resistance with improvements in material removal and maximum depth up to 19% and 8%, respectively. On the other hand, two layers of polyurethane provided material removal improvements up to 38%, while a combination of polyurethane layer on top of IA-700 (graphene coating) showed the best erosion resistance behavior at normal impact with improvements reaching 15%.
•Solid particle erosion of GFRP specimens with graphene-based coatings was explored.•Graphene-based coatings showed a decrease in material removal and in maximum depth.•Combining polyurethane and graphene coatings layers improved erosion resistance.•Coatings with soft layer on top of hard layer showed best erosion resistance.
Macrophages exist in various tissues, several body cavities, and around mucosal surfaces and are a vital part of the innate immune system for host defense against many pathogens and cancers. ...Macrophages possess binary M1/M2 macrophage polarization settings, which perform a central role in an array of immune tasks via intrinsic signal cascades and, therefore, must be precisely regulated. Many crucial questions about macrophage signaling and immune modulation are yet to be uncovered. In addition, the clinical importance of tumor-associated macrophages is becoming more widely recognized as significant progress has been made in understanding their biology. Moreover, they are an integral part of the tumor microenvironment, playing a part in the regulation of a wide variety of processes including angiogenesis, extracellular matrix transformation, cancer cell proliferation, metastasis, immunosuppression, and resistance to chemotherapeutic and checkpoint blockade immunotherapies. Herein, we discuss immune regulation in macrophage polarization and signaling, mechanical stresses and modulation, metabolic signaling pathways, mitochondrial and transcriptional, and epigenetic regulation. Furthermore, we have broadly extended the understanding of macrophages in extracellular traps and the essential roles of autophagy and aging in regulating macrophage functions. Moreover, we discussed recent advances in macrophages-mediated immune regulation of autoimmune diseases and tumorigenesis. Lastly, we discussed targeted macrophage therapy to portray prospective targets for therapeutic strategies in health and diseases.
The explosive popularity of small-cell and Internet of Everything devices has tremendously increased traffic loads. This increase has revolutionised the current network into 5G technology, which ...demands increased capacity, high data rate and ultra-low latency. Two of the research focus areas for meeting these demands are exploring the spectrum resource and maximising the utilisation of its bands. However, the scarcity of the spectrum resource creates a serious challenge in achieving an efficient management scheme. This work aims to conduct an in-depth survey on recent spectrum sharing (SS) technologies towards 5G development and recent 5G-enabling technologies. SS techniques are classified, and SS surveys and related studies on SS techniques relevant to 5G networks are reviewed. The surveys and studies are categorised into one of the main SS techniques on the basis of network architecture, spectrum allocation behaviour and spectrum access method. Moreover, a detailed survey on cognitive radio (CR) technology in SS related to 5G implementation is performed. For a complete survey, discussions are conducted on the issues and challenges in the current implementation of SS and CR, and the means to support efficient 5G advancement are provided.
New adsorbent polyvinyl alcohol/magnesium peroxide (PVA/MgO2) nano-composite films have been designed for high selective adsorption and dye removal applications. Creation of MgO2 within 40 ± 3 nm has ...been confirmed by TEM. PVA/MgO2 films have a large surface area of 59.130 m2 g−1, high pore volume 0.191 cm3 g−1 and a high negative surface charge _ 36.4 mV at pH environment ~12, which plays an important role in increasing the uptake capacity, removal efficiency and the selective adsorption performance. PVA/MgO2 nano-composite shows a high selective adsorption for MB dyes from a mixture solution containing both MB and MO dyes. Experiments showed that 30 mg of PVA/MgO2 has the ability to remove 50 mL of 25 mg/L of MB dye with an efficiency (99.9 ± 0.1%) in a fast time ~15 min under the experimental conditions. The Langmuir model is the isotherm model, the pseudo second order is the adsorption kinetics as well as the exothermic is thermodynamic process of the adsorption process. In addition, PVA/MgO2 nano-composite shows a high catalytic activity, in the recycling test, for ten cycles of MB adsorption.
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•New PVA/MgO2 nanocomposites were prepared by casing method for selecting and removing MB dyes for the first time.•PVA/MgO2 has a high surface area of 59.130 m2 g−1 and a high negative surface charge _ 36.4 mV.•PVA/MgO2 shows a high catalytic selectivity for MB dyes from mixture solution containing both MB and MO dyes.•30 mg of PVA/MgO2 has the ability to remove 50 mL of 25 mg/L of MB dye with efficiency (99.9 ± 0.1%) in a fast time 15 min.•PVA/MgO2 shows a high catalytic activity, in the recycling test, for ten cycles of MB degradation.
A library of novel bis-Schiff base derivatives based on thiobarbituric acid has been effectively synthesized by multi-step reactions as part of our ongoing pursuit of novel anti-diabetic agents. All ...these derivatives were subjected to in vitro α-glucosidase inhibitory potential testing after structural confirmation by modern spectroscopic techniques. Among them, compound 8 (IC
= 0.10 ± 0.05 µM), and 9 (IC
= 0.13 ± 0.03 µM) exhibited promising inhibitory activity better than the standard drug acarbose (IC
= 0.27 ± 0.04 µM). Similarly, derivatives (5, 6, 7, 10 and 4) showed significant to good inhibitory activity in the range of IC
values from 0.32 ± 0.03 to 0.52 ± 0.02 µM. These derivatives were docked with the target protein to elucidate their binding affinities and key interactions, providing additional insights into their inhibitory mechanisms. The chemical nature of these compounds were reveal by performing the density functional theory (DFT) calculation using hybrid B3LYP functional with 6-311++G(d,p) basis set. The presence of intramolecular H-bonding was explored by DFT-d3 and reduced density gradient (RGD) analysis. Furthermore, various reactivity parameters were explored by performing TD-DFT at CAM-B3LYP/6-311++G(d,p) method.
In this literature, we have successfully designed novel silver decorated nitrogen doped carbon dots/poly(3,4-ethylene-dioxythiophene):poly(styrenesulphonate)/poly (vinyl alcohol) ...(Ag@NCDots/PEDOT:PSS/PVA) nano-composite films for thermoelectric applications. The anisotropic (in plane//and through plane ⊥) thermoelectric functions are briefly studied, however we have focused on the through plane thermoelectric functions. It was found that both σ⊥ and σ//values increase with increasing the Ag@NCDots to be σ⊥ = 181.7 ± 11 S/cm and σ//= 287.4 ± 19 S/cm at 8 wt%, thanks to the creation of conductive paths inside the films and the increment in both carrier mobility and carrier concentration. Although k//~1.8k⊥ was achieved at 8 wt% of Ag@NCDots, the films showed an under control behavior for k⊥ with a value (0.195 W/mK) due to the creation of a gaseous atmosphere of nitrogen which occupies the defects and voids in the nano-composite. S//and S⊥ values increase and the value of S⊥ (77.5 ± 1.7 μV/K) has been achieved at 8 wt% of Ag@NCDots. The PF⊥ ~109.20 ± 4 μV/mK2 and a ZT⊥ ~0.148 have been achieved at a minute concentration of Ag@NCDots (8 wt%) at room temperature. PF//shows higher values than PF⊥ because σ//is higher than σ⊥, while ZT//shows a smaller value than that in ZT⊥ at 8 wt% of Ag@NCDots as k⊥ is lower than k//. The films exhibited a much higher tensile strength (127.8 MPa) than PEDOT:PSS/PVA (42.2 MPa) and Young's modulus (1.52 GPa) larger than PEDOT:PSS/PVA (0.29 GPa) at the 8 wt% of Ag@NCDots, proving the excellent properties of this nano-composite for thermoelectric applications. 12 legs flexible thermoelectric generator has been engineered with an ability to generate an output voltage of (Voutput = 15.12 mV) at a ΔT = 16 K. Finally, this nano-composite has a promising functional application as a flexible thermal sensor and wearable thermoelectric generators thanks to its unique properties and easy reproducibility.
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•Ag@NCDos/PEDOT:PSS/PVA nanocomposite films were synthesized for thermoelectric application.•The anisotropic (in plane//and through plane ⊥) thermoelectric functions have been studied.•Ag@NCDos/PEDOT:PSS/PVA nanocomposite showed under control through plane thermal conductivity.•PEDOT:PSS/NC@Te showed a k∥ ˃ k⊥ with an under control k⊥ behavior with k = 0.19 W/mK.•The S⊥ = 77.5 ± 1.7 μV/K, PF⊥ = 109.20 ± 4 μV/mK2 and zT⊥ ~0.148 were achieved at a very small NC (8 wt%) at R.T.
Secondary plant metabolites remain one of the key sources of therapeutic agents despite the development of new approaches for the discovery of medicinal drugs. In the current study, chemical ...analysis, and biological activities of Kei apple (Dovyalis caffra) methanolic extract were evaluated. Chemical analysis was performed using HPLC and GC-MS. Antiviral and anticancer effect were assessed using the crystal violet technique and activity against human liver cells (HepG2), respectively. Antibacterial activity was tested with the disc diffusion method. The obtained results showed that chlorogenic acid (2107.96 ± 0.07 µg/g), catechin (168 ± 0.58 µg/g), and gallic acid (15.66 ± 0.02 µg/g) were the main bioactive compounds identified by HPLC techniques. While, compounds containing furan moieties, as well as levoglucosenone, isochiapin B, dotriacontane, 7-nonynoic acid and tert-hexadecanethiol, with different biological activities were identified by GC-MS. Additionally, inhibition of 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) scavenging was 79.25% at 2000 µg/mL, indicating its antioxidant activity with IC
of 728.20 ± 1.04 µg/mL. The tested extract exhibited potential anticancer activity (58.90% toxicity) against HepG2 cells at 1000 µg/mL. Potential bacterial inhibition was observed mainly against Escherichia coli and Proteus vulgaris, followed by Staphylococcus aureus and Bacillus subtilis with a diameter of growth inhibition ranging from 13 to 24 mm. While weak activities were recorded for fungi Candida albicans (10 mm). The extract showed mild antiviral activity against human coronavirus 229E with a selective index (SI) of 10.4, but not against human H3N2 (SI of 0.67). The molecular docking study's energy ratings were in good promise with the experiment documents of antibacterial and antiviral activities. The findings suggest that D. caffra juice extract is a potential candidate for further experiments to assess its use as potential alternative therapeutic agent.
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