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The growing problems of soil erosion and sedimentation due to plantation and construction activities highlight the importance of reliable information on sediment sources with the objectives of designing and implementing targeted management practices. However, reliable information is unavailable for mountainous catchments in southern China. Accordingly, the fingerprinting approach was adopted to quantitatively identify sediment sources in a typical mountainous catchment disturbed by plantation and construction activities in the Dadingshan catchment, Guangdong Province, China. Sensitivity tests were conducted to evaluate the effect of correction factors on the modified model. The results indicated that geochemical elements could be applied for identifying sediment sources within the study catchment. However, the coarse sediment in the catchment posed challenges to the conservative behaviour of tracers. The findings suggested that the primary sediment source is exposed subsoil (51.5 ± 10.0%), followed by plantation topsoil (35.3 ± 16.2%) and wind farms (13.2 ± 10.2%). The mean goodness‐of‐fit value for all sediment samples was 87.1 ± 5.7%. The sediment contributions of various sources varied significantly due to differences in the extent and intensity of human intervention and the main erosion type of each source. Sensitivity analysis revealed that considering the assumption of source normality improved the source apportionment accuracy. However, particle size correction and tracer within‐source variability weighting in the modified mixing model resulted in unusual estimates of the source contributions. This contribution highlights the significance of considering uncertainties in key fingerprinting‐related aspects and emphasizes the need for implementing sediment control strategies in degraded forest environments. [ABSTRACT FROM AUTHOR]

The technological advancements made in optics and semiconductors (e.g., cameras and laser diodes) working with infrared have brought interest in optical bioimaging back to the forefront of research investigating in vivo medical imaging techniques. The definition of the near-infrared transparency windows has turned optical imaging into more than just a method for topical imaging applications. Moreover, this has focused attention back to tissue fluorescence, emissions by tissues and organs that occur when excited by external illumination sources. Most endogenous fluorophores emit in the blue to green range of the electromagnetic spectrum and the resulting tissue fluorescence can be employed in studies from cells to tissue metabolism or avoided by shifting to the red if seen as unwanted autofluorescence. With the more recent move to infrared, it was discovered that autofluorescence is not limited to the visible but also strongly affects in vivo imaging in the infrared. In this Tutorial, we give an overview on tissue fluorescence and tissue interactions with excitation light as well as their effect on in vivo imaging. Furthermore, potential sources of tissue fluorescence in the near-infrared are identified and we describe approaches for successful biomedical imaging in the biological windows, taking into consideration infrared autofluorescence and summarizing techniques for avoiding it in in vivo imaging experiments. [ABSTRACT FROM AUTHOR]

Unreasonable exploitation oi artificial forest causes severe soil erosion in the mountainous areas of sou¬thern China. The spatial-temporal variations of soil erosion in typical small watershed with artificial forest has signifi¬cant implications for artificial forest exploitation and sustainable development of mountainous ecological environ¬ment. In this study, we used revised universal soil loss equation ( RUSLE) and geographic information system ( GIS) to evaluate the spatial and temporal variations of soil erosion and its key drivers of Dadingshan watershed in mountainous area of western Guangdong. The results showed that the erosion modulus was 1948.1 t ⋅ km-2 ⋅ a-1 (belonging to light erosion) in the Dadingshan watershed. However, the spatial variation of soil erosion was sub¬stantial, with variation coefficient of 5.12. The maximal soil erosion modulus was 191127 t ⋅ km-2 ⋅a-1. Slight ero¬sion (<500 t ⋅ km-2 ⋅ a-1 ) accounted for 80.6% of the total watershed area. The moderate erosion and above ( >2500 t ⋅ km-2 a-1) were mainly distributed in young Eucalyptus forest area with less than 30% of the vegeta¬tion coverage, which contributed nearly 75.7% of total soil erosion. During 2014-2019, the interannual variations of mean erosion of Dadingshan catchment was modest, but the spatial variation of soil erosion was large. Vegetation cover, slope, and rainfall were key drivers of such variation. The destruction of natural vegetation resulted by plan¬tation exploitation was the primary cause of soil erosion in afforestation areas. Soil erosion significantly increased with the increases of slope gradient in the young forest area, which was aggravated by extreme rainfall. However, soil erosion gradually decreased with the increases of the age of Eucalypt plantation. Therefore, the hot spot of soil erosion was young forest areas of Eucalypt plantation with slope >25°, and the key period for soil erosion control was the first 2-3 years after Eucalyptus planting. We suggested that reasonable afforestation measures should be used in area with >25° slopes, and that the destruction of natural vegetation should be avoided on hillslope with >35° slope gradient. The road construction standards and forest management should be further improved to address the challenge of extreme rainfalls. [ABSTRACT FROM AUTHOR]

Luminescent nano‐thermometry is a fast‐developing technique with great potential for in vivo sensing, diagnosis, and therapy. Unfortunately, it presents serious limitations. The luminescence generated by nanothermometers, from which thermal readout is obtained, is strongly distorted by the attenuation induced by tissues. Such distortions lead to low signal levels and entangle absolute and reliable thermal monitoring of internal organs. Overcoming both limitations requires the use of high‐brightness luminescent nanothermometers and adopting more complex approaches for temperature estimation. In this work, it is demonstrated how superbright Ag2S nanothermometers can provide in vivo, reliable, and absolute thermal reading of the liver during laser‐induced hyperthermia. For that, a new procedure is designed in which thermal readout is obtained from the combination of in vivo transient thermometry measurements and in silico simulations. The synergy between in vivo and in silico measurements has made it possible to assess relevant numbers such as the efficiency of hyperthermia processes, the total heat energy deposited in the liver, and the relative contribution of Ag2S nanoparticles to liver heating. This work provides a new way for absolute thermal sensing of internal organs with potential application not only to hyperthermia processes but also to advanced diagnosis and therapy. [ABSTRACT FROM AUTHOR]

The emergence of luminescence nanothermometry in bio and nanomedicine has enabled achievements outside the reach of conventional techniques. For instance, it has provided real‐time monitoring of in vivo thermal therapies of tumors, a mandatory requirement for these techniques to work safely and efficiently. However, the reliability of intratumoral thermal readings is currently in question due to the presence of artefacts caused by the inhomogeneous optical properties of biological tissues. This work demonstrates how it is possible to avoid, under specific conditions, these artefacts and reach precise and reliable in vivo intratumoral thermal feedback during in vivo photothermal treatments. The method proposed is based on the use of luminescent nanoparticles capable of multiparametric thermal sensing. The results demonstrate how the convergence of the different thermal readouts becomes a solid indicator of their reliability. It is shown how this new approach makes possible precise (thermal uncertainties below 1 °C) intratumoral thermal feed‐back, while simple, efficient, and minimally invasive in vivo thermal treatments of surface tumors is carried out. Results included in this work provide an ingenious route toward the consolidation of luminescence nanothermometry as a convincing technique for high sensitivity preclinical thermal sensing, while also constituting a step toward improved photothermal therapies. [ABSTRACT FROM AUTHOR]

Despite showing great promise in bioapplications, lanthanide-doped upconversion nanoparticles (UCNPs) are still restricted by low upconversion efficiency. In this work, ultra-small, monodisperse and uniform β-NaYbF4:0.5% Tm NPs were successfully prepared through a solvothermal route, and remarkably enhanced ultraviolet upconversion luminescence (UV UCL) had been achieved via Fe3+ doping. The UV UCL enhancement in NaYbF4:0.5% Tm NPs was investigated in detail. It was found that the UCL intensities of the UV and blue emissions of NPs doped with 5 mol% Fe3+ ions were enhanced by 10 and 6 times, respectively, compared to that of the Fe3+-free sample. The enhancement of UV UCL is mainly ascribed to the high population density of excited Yb3+ and the energy transfer from ☋2F7/2, 4T1g ＞ (Yb3+–Fe3+ dimer) to 3F2,3 (Tm3+) states. Moreover, through dynamic analysis, we further demonstrate the proposed mechanisms of UC processes. The results suggest that ultra-small UCNPs with enhanced UV UCL may have potential applications in the biomedical field. [ABSTRACT FROM AUTHOR]

Ag2S nanoparticles are near-infrared (NIR) probes providing emission in a specific spectral range (~1200 nm), and superparamagnetic iron oxide nanoparticles (SPION) are colloidal systems able to respond to an external magnetic field. A disadvantage of Ag2S NPs is the attenuated luminescent properties are reduced in aqueous media and human fluids. Concerning SPION, the main drawback is the generation of undesirable clusters that reduce particle stability. Here, we fabricate biocompatible hybrid nanosystems combining Ag2S NPs and SPION by the electrospraying technique for drug delivery purposes. These nanostructures are composed of poly(lactic-co-glycolic acid) (PLGA) as the polymeric matrix in connection with both Ag2S NPs and SPIONs. Initially, we fabricate a hybrid colloidal nanosystem composed of Ag2S NPs in connection with PLGA (PLGA@Ag2S) by three different routes, showing good photoluminescent (PL) properties with relatively high average decay times. Then, we incorporate SPIONs, obtaining a PLGA polymeric matrix containing both Ag2S NPs and SPION (PLGA@Ag2S@SPION). Interestingly, in this hybrid system, the location of Ag2S NPs and SPIONs depends on the synthesis route performed during electrospraying. After a detailed characterization, we demonstrate the encapsulation and release capabilities, obtaining the kinetic release using a model chemotherapeutic drug (maslinic acid). Finally, we perform in vitro cytotoxicity assays using drug-loaded hybrid systems against several tumor cell lines. [ABSTRACT FROM AUTHOR]

Ag 2 S nanoparticles are the staple for high-resolution preclinical imaging and sensing owing to their photochemical stability, low toxicity, and photoluminescence (PL) in the second near-infrared biological window. Unfortunately, Ag 2 S nanoparticles exhibit a low PL efficiency attributed to their defective surface chemistry, which curbs their translation into the clinics. To address this shortcoming, we present a simple methodology that allows to improve the PL quantum yield from 2 to 10%, which is accompanied by a PL lifetime lengthening from 0.7 to 3.8 μs. Elemental mapping and X-ray photoelectron spectroscopy indicate that the PL enhancement is related to the partial removal of sulfur atoms from the nanoparticle's surface, reducing surface traps responsible for nonradiative de-excitation processes. This interpretation is further backed by theoretical modeling. The acquired knowledge about the nanoparticles' surface chemistry is used to optimize the procedure to transfer the nanoparticles into aqueous media, obtaining water-dispersible Ag 2 S nanoparticles that maintain excellent PL properties. Finally, we compare the performance of these nanoparticles with other near-infrared luminescent probes in a set of in vitro and in vivo experiments, which demonstrates not only their cytocompatibility but also their superb optical properties when they are used in vivo, affording higher resolution images.