Validation, analysis, and comparison of MISR V23 aerosol optical depth products with MODIS and AERONET observations.

The latest Multi-angle Imaging Spectro Radiometer (MISR) Version (V) 23 aerosol optical depth (AOD) products were released, with an improved spatial resolution of 4.4 km, providing an unprecedented opportunity for the refined regional application. To ensure the reliability of their applications and build a scientific reference for the further optimization, it is imperative to conduct a comprehensive evaluation, especially for the unique size-resolved AOD products: small-size AOD (AODS, representing the contribution of fine-mode aerosols), medium-size AOD (AODM), and large-size AOD (AODL), and AODM+L represents the AOD part of coarse-mode aerosols. AErosol RObotic NETwork (AERONET) and MODerate-resolution Imaging Spectroradiometer (MODIS) Collection (C) 6.1 aerosol products from 2001 to 2020 are utilized for the validation, analysis, and inter-comparison, considering three spatial scales and four key factors. In general, MISR V23 aerosol products show a good accuracy compared with AERONET. The best performance for all AOD products appears in forest units (the highest R ~ 0.93, data percentage within Expected Error bounds, %EE > 93), related to the inactive human activity and dark underlying surface. Dependences of retrieval deviations illustrate that the performance of MISR AOD deteriorates as aerosol loading increases. Namely, with the increase of aerosols, total AOD (AODT) and AODS show increasing negative deviations, while increasing positive deviations are observed for AODM+L. This suggests that the Empirical Orthogonal Functions do not perform well in this situation, since numerous aerosol particles can obstruct the underlying reflection and reduce the surface spectral contrast. In addition, AODT and AODS often exhibit anomalous positive deviations in areas with low vegetation cover, such as deserts, revealing that MISR will overestimate aerosol content over bright surfaces and in environments dominated by coarse-mode particles. The above findings not only deepen the understanding of MISR aerosols products from multiple perspectives, but also provide useful information for the product improvement.

Aerosol optical properties of haze episodes in eastern China based on remote-sensing observations and WRF-Chem simulations.

The ability for remote-sensing sensors and global/regional models to describe aerosol optical properties (AOPs) is critical to reducing the uncertainty in aerosol radiative forcing associated with climate change, and improving model prediction accuracy. In this study, remote-sensing observations and WRF-Chem simulations were used to evaluate AOPs over Eastern China during a severe winter haze event, in terms of aerosol optical depth (AOD), Ångström exponent (AE) and aerosol extinction profiles (AEP). This study also characterizes whether the inclusion of aerosol radiative feedbacks (ARFs) may improve the ability of WRF-Chem to acquire AOPs during haze episodes. Three simulation scenarios were considered: the non-radiation feedback (NRF), aerosol direct effect (ADE), as well as combined ADE and aerosol indirect effect (ADE + AIE). The results indicate that the satellite AOD products could represent the spatiotemporal distribution characteristics of the haze event. The AOD retrieved by the MODIS C6.1 DB algorithm was highly consistent with ground-based observations. A comparison between simulations and observations demonstrated that WRF-Chem, including the ADE or ADE + AIE scheme, may improve AOPs simulation in heavily polluted areas. The most significant improvements occurred in the Sichuan basin (SB) and North China Plain (NCP) (AOD = 50-70%; AE = 10-20%). In particular, the ADE + AIE scheme was the most obvious for AOD improvement, followed by AE. The AEP was also qualitatively analyzed through simulations and observations, and the result showed that the model overestimates aerosol extinction coefficients in NCP. However, the model is still able to represent the entire AEP contour over East China. Similar to AOD and AE, the model can also improve AEP simulation by adding ADE or ADE + AIE scheme, especially in SB. In summary, it is found that the ability of WRF-Chem to simulate the AOPs was significantly enhanced, particularly for regions loading with heavy aerosol during haze events in Eastern China.

Comparison of AOD from CALIPSO, MODIS, and Sun Photometer under Different Conditions over Central China.

Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) provides three-dimensional information on aerosol optical properties across the globe. However, the performance of CALIPSO aerosol optical depth (AOD) products under different air quality conditions remains unclear. In this research, three years of CALIPSO level 2 AOD data (November 2013 to December 2017) were employed to compare with the Moderate Resolution Imaging Spectroradiometer (MODIS) level 2 columnar AOD products and ground-based sun photometer measurements for the same time period. To investigate the effect of air quality on AODs retrieved from CALIPSO, the AODs obtained from CALIPSO, MODIS, and sun photometer were inter-compared under different air quality conditions over Wuhan and Dengfeng. The average absolute bias of AOD between CALIPSO and sun photometer was 0.22 ± 0.21, 0.11 ± 0.07, and 0.14 ± 0.13 under clean, moderate, and polluted weather, respectively. The result indicates that the CALIPSO AOD were more reliable under moderate and polluted days. Moreover, the deviation of AOD between CALIPSO and sun photometer was largest (0.23 ± 0.21) in the autumn season, and lowest (0.13 ± 0.12) in the winter season. The results show that CALIPSO AOD products were more applicable to regions and seasons with high aerosol concentrations.

Pulmonary delivery of tea tree oil-ß-cyclodextrin inclusion complexes for the treatment of fungal and bacterial pneumonia.

OBJECTIVES: Bacterial pneumonia is a common cause of death worldwide. Tea tree oil (TTO) is a potent antimicrobial natural product, which is formulated in dry powder inhalers (DPIs) for the treatment of fungal and bacterial pneumonia. METHODS: Tea tree oil-ß-cyclodextrin inclusion complexes (TTO-ß-CD) were prepared and characterized. Aerodynamic properties of TTO-ß-CD powders were measured. The rat models of fungal (Candida albicans) and bacterial (Acinetobacter baumannii) pneumonia were prepared. Saline, TTO, TTO-ß-CD and the positive drug (fluconazole or penicillin) were directly delivered to the rat lungs. Pathological and biological assays were conducted. KEY FINDINGS: Tea tree oil-ß-CD powders had an appropriate aerodynamic diameter of 5.59 µm and the fine particle fraction of 51.22%, suitable for pulmonary delivery. TTO-ß-CD showed higher and similar antipneumonic effects on the rat models than fluconazole and penicillin, respectively. The effects of TTO-ß-CD were higher than TTO alone. The antipneumonic mechanisms involved blocking the recruitment of leucocytes and neutrophils, eliminating the microbes, downregulating pro-inflammatory cytokines (including tumour necrosis factor-α, interleukin-1ß and interleukin-6), suppressing cyclooxygenase 2 expression, and further reducing lung injury. CONCLUSIONS: Inhaled TTO-ß-CD powders have the advantages of portability, high stability, self-administration, high lung deposition and good antipneumonic effect. It is a promising DPI for the treatment of fungal and bacterial pneumonia.

Measurement and Study of Lidar Ratio by Using a Raman Lidar in Central China.

We comprehensively evaluated particle lidar ratios (i.e., particle extinction to backscatter ratio) at 532 nm over Wuhan in Central China by using a Raman lidar from July 2013 to May 2015. We utilized the Raman lidar data to obtain homogeneous aerosol lidar ratios near the surface through the Raman method during no-rain nights. The lidar ratios were approximately 57 ± 7 sr, 50 ± 5 sr, and 22 ± 4 sr under the three cases with obviously different pollution levels. The haze layer below 1.8 km has a large particle extinction coefficient (from 5.4e-4 m(-1) to 1.6e-4 m(-1)) and particle backscatter coefficient (between 1.1e-05 m(-1)sr(-1) and 1.7e-06 m(-1)sr(-1)) in the heavily polluted case. Furthermore, the particle lidar ratios varied according to season, especially between winter (57 ± 13 sr) and summer (33 ± 10 sr). The seasonal variation in lidar ratios at Wuhan suggests that the East Asian monsoon significantly affects the primary aerosol types and aerosol optical properties in this region. The relationships between particle lidar ratios and wind indicate that large lidar ratio values correspond well with weak winds and strong northerly winds, whereas significantly low lidar ratio values are associated with prevailing southwesterly and southerly wind.

Tea tree oil nanoemulsions for inhalation therapies of bacterial and fungal pneumonia.

Tea tree oil (TTO) is a natural essential oil with strong antimicrobial efficacy and little drug resistance. However, the biomedical applications of TTO are limited due to its hydrophobicity and formulation problems. Here, we prepared an inhalable TTO nanoemulsion (nanoTTO) for local therapies of bacterial and fungal pneumonia. The optimal formulation of nanoTTOs consisted of TTO/Cremophor EL/water with a mean size of 12.5nm. The nanoTTOs showed strong in vitro antimicrobial activities on Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus and Candida albicans. After inhalation to the lung, the nanoTTOs had higher anti-fungal effect than fluconazole on the fungal pneumonia rat models with reduced lung injury, highly microbial clearance, blocking of leukocyte recruitment, and decrease of pro-inflammatory mediators. In the case of rat bacterial pneumonia, the nanoTTOs showed slightly lower therapeutic efficacy than penicillin though at a much lower dose. Taken together, our results show that the inhalable nanoTTOs are promising nanomedicines for local therapies of fungal and bacterial pneumonia with no obvious adverse events.

Effects of Incorporating Carboxymethyl Chitosan into PMMA Bone Cement Containing Methotrexate.

Treatment of bone metastases usually includes surgical resection with local filling of methotrexate (MTX) in polymethyl methacrylate (PMMA) cement. We investigated whether incorporating carboxymethyl chitosan (CMCS) in MTX-PMMA cement might overcome disadvantages associated with MTX. To determine the optimal CMCS+MTX concentration to suppress the viability of cancer cells, an integrated microfluidic chip culturing highly metastatic lung cancer cells (H460) was employed. The mechanical properties, microstructure, and MTX release of (CMCS+MTX)-PMMA cement were evaluated respectively by universal mechanical testing machine, scanning electron microscopy (SEM), and incubation in simulated body fluid with subsequent HPLC-MS. Implants of MTX-PMMA and (CMCS+MTX)-PMMA cement were evaluated in vivo in guinea pig femurs over time using spiral computed tomography with three-dimensional image reconstruction, and SEM at 6 months. Viability of H460 cells was significantly lowest after treatment with 57 µg/mL CMCS + 21 µg/mL MTX, which was thus used in subsequent experiments. Incorporation of 1.6% (w/w) CMCS to MTX-PMMA significantly increased the bending modulus, bending strength, and compressive strength by 5, 2.8, and 5.2%, respectively, confirmed by improved microstructural homogeneity. Incorporation of CMCS delayed the time-to-plateau of MTX release by 2 days, but increased the fraction released at the plateau from 3.24% (MTX-PMMA) to 5.34%. Relative to the controls, the (CMCS+MTX)-PMMA implants integrated better with the host bone. SEM revealed pores in the cement of the (CMCS+MTX)-PMMA implants that were not obvious in the controls. In conclusion, incorporation of CMCS in MTX-PMMA appears a feasible and effective modification for improving the anti-tumor properties of MTX-PMMA cement.

An integrated microfluidic device for screening the effective concentration of locally applied tacrolimus for peripheral nerve regeneration.

The effectiveness of tacrolimus (FK506) for the promotion of nerve regeneration is known. However, at present, due to the fact that systemic application may lead to opportunistic infections and tumors, and that the treatment of peripheral nerve injury with systemic immunosuppression is not generally accepted, FK506 has not been widely used for the treatment of simple or peripheral nerve injury. In this study, a pyramid-shaped microfluidic device was designed and fabricated that was able to analyze the effective concentration of locally applied FK506. After testing the effectiveness of the microfluidic device by measuring the fluorescence intensity of fluorescein isothiocyanate-dextran, rat Schwann cells (SCs) were loaded into the device and cultured for 9 days in the presence of different concentrations of FK506. SC proliferation in the presence of FK506 was concentration-dependent between 0 and 2.5±0.003 ng/ml. The proliferation rate reached a maximum at 1.786±0.014 ng/ml, which was statistically significantly different from the proliferation rate at lower FK506 concentrations. There was no statistically significant difference in the proliferation rate between the 1.786 ng/ml group and groups of higher FK506 concentrations. Furthermore, the SCs in the microfluidic device and a 96-well plate continued to proliferate as the culture time increased. No statistically significant differences were identified between the microfluidic device and a 96-well plate with regard to the proliferation rates in each corresponding group. The results obtained in this study demonstrated that the microfluidic device can be used as an excellent platform for the study of drug concentration at the cellular level, and the effective FK506 concentration for local application is 1.786±0.014 ng/ml.

Transdermal enhancement effect and mechanism of iontophoresis for non-steroidal anti-inflammatory drugs.

Iontophoresis is an important approach to improve transdermal drug delivery. However, The transdermal enhancement mechanism of iontophoresis was not well known. The relationship between the physicochemical properties of drugs and the transdermal enhancement effect of iontophoresis was revealed in this study. Non-steroidal anti-inflammatory drugs (NSAIDs) were used as the models, including aspirin, ibuprofen and indomethacin. Their oil-water partition coefficients were measured. The carbomer-based hydrogels of them were prepared. Iontophoresis significantly enhanced in vitro transdermal delivery across the rat skins. Strong lipophilicity could lead to high permeation of drugs. However, the dissociation extent (indicated as pKa) of drugs was the key factor to determine the transdermal enhancement effect of iontophoresis. The more dissociation the drugs were, the higher the transdermal enhancement effect of iontophoresis. The drug-loaded hydrogels combined with iontophoresis improved the treatment of rat raw's inflammatory syndrome. Iontophoresis significantly improved the drugs penetrating into the hypodermis, dermis and epidermis, more deeply than the application of drugs alone according to the experimental result of 5-carboxylfluorescein hydrogels. Iontophoresis led to the unordered arrangement of skin intercellular lipids, the significantly increased flowability and loose stratum corneum structure. Iontophoresis is a promising approach to improve transdermal drug delivery with safety and high efficiency.