Total biosynthesis of fungal tetraketide pyrones

Fungal tetraketide pyrones possess important and potent bioactivities, but their detailed biosynthetic pathways are unknown and synthetic routes to their production are lengthy. Here we investigated the fungal pathways to the multiforisins and compounds related to islandic acid. Heterologous expression experiments yield high titres of these compounds and pathway intermediates. The results both elucidate the pathway and offer a platform for the total biosynthesis of this class of metabolites

Polyethylene Glycol-grafted poly alpha-lipoic acid-dexamethasone nanoparticles for osteoarthritis

Osteoarthritis (OA) is a chronic inflammatory disease that causes synovial hyperplasia, cartilage destruction, and the formation of bone spurs. Macrophages play an indispensable role in the pathogenesis of OA by producing proinflammatory cytokines. To achieve the effect of arthritis, hormones can effectively inhibit the progression of inflammation by inhibiting the secretion of inflammatory cytokines by macrophages in traditional therapy. However, the drug is quickly cleared from the joint space, and the high injection site infection rate and low local drug concentration make the clinical efficacy of corticosteroids greatly reduced. We described the design and preparation of Polyethylene Glycol-grafted Poly Alpha-lipoic Acid-dexamethasone Nanoparticles (NPDXM/PPLA), elucidated the mechanism of action of NPDXM/PPLA in the treatment of OA in mice, and provided an experimental basis for investigating the treatment of OA with polymer nanoparticles loaded with dexamethasone. Flow cytometry and confocal laser scanning microscopy were used to confirm that NPDXM/PPLA was well absorbed and released by macrophages, and it was discovered that NPDXM/PPLA could efficiently reduce the proliferation of activated macrophages (RAW 264.7 cells). Enzyme-linked immunosorbent assay revealed that NPDXM/PPLA could efficiently reduce the expression of proinflammatory cytokines IL-1β, IL-6, and TNF-α. The knee bone structure of OA mice was investigated by MicroCT, and it was discovered that intraarticular injection of NPDXM/PPLA effectively alleviated the bone damage of the articular cartilage. Therefore, NPDXM/PPLA is a potential therapeutic nanomedicine for the treatment of OA

Performance Assessment of Mobile Rayleigh Doppler Lidars for Middle Atmosphere Research

Recently, two sets of mobile Rayleigh Doppler lidars were implemented in University of Science and Technology of China (USTC) for atmospheric gravity waves research. One of them works in a step stare scanning mode with azimuths corresponding to four cardinal points, while the other one consists of three fixed subassemblies: one points to the zenith and the two others are titled at 30° from the zenith with east and north pointings, respectively. They both operate at eye-safe wavelength 354.7 nm and adopt a triple Fabry-Perot interferometer (FPI) as frequency discriminator. In order to assess the performance of the Doppler lidars, comparison experiments were performed between them. Perhaps, it is the first time to make direct comparison between scanning and non-scanning Rayleigh Doppler lidars

Significance of Determination Methods on Shear Modulus Measurements of Fujian Sand in Cyclic Triaxial Testing

It has long been known that the hysteresis loops of sand under cyclic loading gradually become asymmetric with the increase of strain amplitudes, but a symmetrical hysteresis loop is widely assumed in current practice. Despite several methods which have been proposed recently to consider the hysteresis loop irregularities, previous research has lacked a quantitative study on the effects of determination methods on the shear modulus G and modulus reduction curve G/Gmax. The primary objective of the current study is to evaluate the uncertainties associated with the shear modulus measurements introduced by four determination methods. Reconstituted sand specimens prepared at three relative densities are tested using strain-controlled cyclic triaxial tests, at various effective confining pressures. The results in terms of G and G/Gmax with increasing shear strain are presented, following by the difference quantification in the calculated G/Gmax caused by the determination methods, the Gmax definition and the cycle number. The results show that the calculated G/Gmax may differ significantly for the same hysteresis loop, with a maximum percentage change of 40~50%. The aggravated influence at low confining pressure highlights that careful consideration of the asymmetrical hysteresis loop at large strains is warranted

Significance of Determination Methods on Shear Modulus Measurements of Fujian Sand in Cyclic Triaxial Testing

It has long been known that the hysteresis loops of sand under cyclic loading gradually become asymmetric with the increase of strain amplitudes, but a symmetrical hysteresis loop is widely assumed in current practice. Despite several methods which have been proposed recently to consider the hysteresis loop irregularities, previous research has lacked a quantitative study on the effects of determination methods on the shear modulus G and modulus reduction curve G/Gmax. The primary objective of the current study is to evaluate the uncertainties associated with the shear modulus measurements introduced by four determination methods. Reconstituted sand specimens prepared at three relative densities are tested using strain-controlled cyclic triaxial tests, at various effective confining pressures. The results in terms of G and G/Gmax with increasing shear strain are presented, following by the difference quantification in the calculated G/Gmax caused by the determination methods, the Gmax definition and the cycle number. The results show that the calculated G/Gmax may differ significantly for the same hysteresis loop, with a maximum percentage change of 40~50%. The aggravated influence at low confining pressure highlights that careful consideration of the asymmetrical hysteresis loop at large strains is warranted

NumericalWeather Predictions and Re-Analysis as Input for Lidar Inversions: Assessment of the Impact on Optical Products

The atmospheric molecular number density can be obtained from atmospheric temperature and pressure profiles and is a significant input parameter for the inversion of lidar measurements. When measurements of vertical profiles of temperature and pressure are not available, atmospheric models are typically considered a valid alternative option. This paper investigates the influence of different atmospheric models (forecast and reanalysis) on the retrieval of aerosol optical properties (extinction and backscatter coefficients) by applying Raman and elastic-only methods to lidar measurements, to assess their use in lidar data processing. In general, reanalyzes are more accurate than forecasts, but, typically, they are not delivered in time for allowing near-real-time lidar data analysis. However, near-real-time observation is crucial for real-time monitoring of the environment and meteorological studies. The forecast models used in the paper are provided by the Integrated Forecasting System operated by the European Centre for Medium-RangeWeather Forecasts (IFS_ECMWF) and the Global Data Assimilation System (GDAS), whereas the reanalysis model is obtained from the fifth-generation European Centre for Medium-RangeWeather Forecasts ReAnalysis v5 (ERA5). The lidar dataset consists of measurements collected from four European Aerosol Research Lidar Network (EARLINET) stations during two intensive measurement campaigns and includes more than 200 cases at wavelengths of 355 nm, 532 nm, and 1064 nm. We present and discuss the results and influence of the forecast and reanalysis models in terms of deviations of the derived aerosol optical properties. The results show that the mean relative deviation in molecular number density is always below 3%, while larger deviations are shown in the derived aerosol optical properties, and the size of the deviation depends on the retrieval method together with the different wavelengths. In general, the aerosol extinction coefficient retrieval is more dependent on the model used than the aerosol backscatter retrievals are. The larger influence on the extinction retrieval is mainly related to the deviation in the gradient of the temperature profile provided by forecast and reanalysis models rather than the absolute deviation of the molecular number density. We found that deviations in extinction were within 5%, with a probability of 83% at 355 nm and 60% at 532 nm. Moreover, for aerosol backscatter coefficient retrievals, different models can have a larger impact when the backscatter coefficient is retrieved with the elastic method than when the backscatter coefficient is calculated using the Raman method at both 355 nm and 532 nm. In addition, the atmospheric aerosol load can also influence the deviations in the aerosol extinction and backscatter coefficients, showing a larger impact under low aerosol loading scenarios.This work was supported by ACTRIS-PPP (preparatory phase) project funded from European Union’s Horizon 2020 Coordination and Support Action (grant agreement no. 739530), ACTRISIMP (implementation) project, funded in the frame of the H2020 program (grant agreement no. 871115), CAMS21b project, funded within the Framework Agreement ECMWF/COPERNICUS/2019/CAMS21b/CNR. D.B. is co-funded by national Portuguese funds through FCT—Fundação para a Ciência e Tecnologia, I.P., in the framework of the ICT project with the references UIDB/04683/2020 and UIDP/04683/2020, as well as through TOMAQAPA (PTDC/CTAMET/29678/2017) and CILIFO (0753_CILIFO_5_E) project

Design of Superhydrophobic Shape Memory Composites with Kirigami Structures and Uniform Wetting Property

With the continuous increase in human demand to improve aircraft performance, intelligent aircraft technologies have become a popular research field in recent years. Among them, the deformable skin structure has become one of the key technologies to achieve excellent and reliable performance. However, during the service, deformable skin structures may encounter problems such as surface impact and adhesion of droplets in rainy weather or surface icing in low-temperature environments, which can seriously affect the flight safety of the aircraft. One way to overcome these issues is to use superhydrophobic shape memory materials in the structure. In this regard, first, shape memory composites were prepared with shape memory epoxy resin as the matrix and carbon fiber orthogonal woven fabric as the reinforcement material. Superhydrophobic shape memory composites (SSMCs) were then obtained by casting the kirigami composite with superhydrophobic carbon nanotube–polydimethylsiloxane (CNT@PDMS) mixture, and the surface was processed by laser micromachining. Shape memory performance and surface wetting performance were determined by material testing methods. The results showed that the shape memory recovery rate can reach 85.11%, the surface is superhydrophobic, the average water contact angle is 156.9 ± 4.4°, and the average rolling angle is 3 ± 0.5°. The three-point bending test of the specimens with different kirigami cell configurations showed that the shape memory composite based on the rectangular structure has the best deformability with an aspect ratio of 0.4. From the droplet impact test, it was found that the impact speed of water droplets and the curvature of the surface can greatly affect the dynamic performance of water. This work is expected to be of significant research value and importance for developing functional deformable skin materials

Simulation of a Pulsed Metastable Helium Lidar

Measurements of atmosphere density in the upper thermosphere and exosphere are of great significance for studying space–atmosphere interactions. However, the region from 200 km to 1000 km has been a blind area for traditional ground-based active remote sensing techniques due to the limitation of facilities and the paucity of neutral atmosphere. To fulfill this gap, the University of Science and Technology of China is developing a powerful metastable helium resonance fluorescent lidar incorporating a 2 m aperture telescope, a high-energy 1083 nm pulsed laser, as well as a superconducting nanowire single-photon detector (SNSPD) with high quantum efficiency and low dark noise. The system is described in detail in this work. To evaluate the performance of the lidar system, numerical simulation is implemented. The results show that metastable helium density measurements can be achieved with a relative error of less than 20% above 370 km in winter and less than 200% in 270–460 km in summer, demonstrating the feasibility of metastable helium lidar