Bidirectional outflows as evidence of magnetic reconnection leading to a solar microflare

Magnetic reconnection is a rapid energy release process that is believed to be responsible for flares on the Sun and stars. Nevertheless, such flare-related reconnection is mostly detected to occur in the corona, while there have been few studies concerning the reconnection in the chromosphere or photosphere. Here we present both spectroscopic and imaging observations of magnetic reconnection in the chromosphere leading to a microflare. During the flare peak time, chromospheric line profiles show significant blueshifted/redshifted components on the two sides of the flaring site, corresponding to upflows and downflows with velocities of $\pm$(70--80) km s$^{-1}$, comparable with the local Alfv\'{e}n speed as expected by the reconnection in the chromosphere. The three-dimensional nonlinear force-free field configuration further discloses twisted field lines (a flux rope) at a low altitude, cospatial with the dark threads in He I 10830 \r{A} images. The instability of the flux rope may initiate the flare-related reconnection. These observations provide clear evidence of magnetic reconnection in the chromosphere and show the similar mechanisms of a microflare to those of major flares.Comment: 16 pages, 5 figures, accepted for publication in ApJ

Antenna arrangement and energy-transfer pathways of PSI-LHCI from the moss Physcomitrella patens

Plants harvest light energy utilized for photosynthesis by light-harvesting complex I and II (LHCI and LHCII) surrounding photosystem I and II (PSI and PSII), respectively. During the evolution of green plants, moss is at an evolutionarily intermediate position from aquatic photosynthetic organisms to land plants, being the first photosynthetic organisms that landed. Here, we report the structure of the PSI-LHCI supercomplex from the moss Physcomitrella patens (Pp) at 3.23 angstrom resolution solved by cryo-electron microscopy. Our structure revealed that four Lhca subunits are associated with the PSI core in an order of Lhca1-Lhca5-Lhca2-Lhca3. This number is much decreased from 8 to 10, the number of subunits in most green algal PSI-LHCI, but the same as those of land plants. Although Pp PSI-LHCI has a similar structure as PSI-LHCI of land plants, it has Lhca5, instead of Lhca4, in the second position of Lhca, and several differences were found in the arrangement of chlorophylls among green algal, moss, and land plant PSI-LHCI. One chlorophyll, PsaF-Chl 305, which is found in the moss PSI-LHCI, is located at the gap region between the two middle Lhca subunits and the PSI core, and therefore may make the excitation energy transfer from LHCI to the core more efficient than that of land plants. On the other hand, energy-transfer paths at the two side Lhca subunits are relatively conserved. These results provide a structural basis for unravelling the mechanisms of light-energy harvesting and transfer in the moss PSI-LHCI, as well as important clues on the changes of PSI-LHCI after landing

Overview on Multienzymatic Cascades for the Production of Non-canonical α-Amino Acids

SM-R thanks the University of Granada for the support provided by project PPJI2017-1 and the European Cooperation in Science and Technology (COST Action CA15133). Authors are also grateful to the Andalusian Regional Government through Endocrinology & Metabolism Group (CTS-202).The 22 genetically encoded amino acids (AAs) present in proteins (the 20 standard AAs together with selenocysteine and pyrrolysine), are commonly referred as proteinogenic AAs in the literature due to their appearance in ribosome-synthetized polypeptides. Beyond the borders of this key set of compounds, the rest of AAs are generally named imprecisely as non-proteinogenic AAs, even when they can also appear in polypeptide chains as a result of post-transductional machinery. Besides their importance as metabolites in life, many of D-α- and L-α-“non-canonical” amino acids (NcAAs) are of interest in the biotechnological and biomedical fields. They have found numerous applications in the discovery of new medicines and antibiotics, drug synthesis, cosmetic, and nutritional compounds, or in the improvement of protein and peptide pharmaceuticals. In addition to the numerous studies dealing with the asymmetric synthesis of NcAAs, many different enzymatic pathways have been reported in the literature allowing for the biosynthesis of NcAAs. Due to the huge heterogeneity of this group of molecules, this review is devoted to provide an overview on different established multienzymatic cascades for the production of non-canonical D-α- and L-α-AAs, supplying neophyte and experienced professionals in this field with different illustrative examples in the literature. Whereas the discovery of new or newly designed enzymes is of great interest, dusting off previous enzymatic methodologies by a “back and to the future” strategy might accelerate the implementation of new or improved multienzymatic cascades.University of Granada PPJI2017-1European Cooperation in Science and Technology (COST) CA15133Andalusian Regional Government through Endocrinology & Metabolism Group CTS-20

Predation on Live and Artificial Insect Prey Shows Different Global Latitudinal Patterns

AimLong-standing theory predicts that the intensity of biotic interactions increases from high to low latitudes. Studies addressing geographic variation in predation on insect prey have often relied on prey models, which lack many characteristics of live prey. Our goals were to explore global latitudinal patterns of predator attack rates on standardised live insect prey and to compare the patterns in predation on live insects with those on plasticine prey models.LocationGlobal forested areas.Time Period2021–2023.Major TaxaArthropods, birds.MethodsWe measured predation rates in 43 forested locations distributed across five continents from 34.1° S to 69.5° N latitude. At each location, we exposed 20 sets of three bait types, one set per tree. Each set included three live fly larvae (maggots), three live fly puparia and three plasticine models of the puparia. We used glue rings to isolate half of the sets from non-flying predators.ResultsArthropod attack rates on plasticine prey decreased linearly from low to high latitudes, whereas attack rates on maggots had a U shaped distribution, with the lowest predation rates at temperate latitudes and the highest rates at tropical and boreal latitudes. This difference emerged from intensive predator attacks on live maggots, but not on plasticine models, in boreal sites. Site-specific attack rates of arthropod predators on live and plasticine prey were not correlated. In contrast, bird attack rates on live maggots and plasticine models were positively correlated, but did not show significant latitudinal changes.Main ConclusionsLatitudinal patterns in predation differ between major groups of predators and between types of prey. Poleward decreases in both arthropod and combined arthropod and bird predation on plasticine models do not mirror patterns of predation on our live prey, the latter likely reflecting real patterns of predation risk better than do patterns of attack on artificial prey

The effect of slag and fly ash content on the properties of electric furnace nickel slag-based geopolymer used for repair materials

Large quantities of electric furnace nickel slag (EFNS) are annually generated through the smelting of ferronickel in industries. EFNS contains a large amount of glass phase SiO2 and MgO, with certain volcanic ash activity. Nevertheless, the lower early activity of EFNS due to the ultra-low Ca and Al greatly limits its application. To descend the consumption of raw materials and mitigate environmental pollution, utilizing such wastes as a binding agent in the domain of repairing mortars is a suitable solution. To address the lack of Ca and Al and adjust the ratios of Ca/Al and Si/Al in EFNS-based mortars, the purpose of the research was to incorporate different contents of slag (SL) and fly ash (FA) from 25% to 40%, respectively, into EFNS-based mortars activated with Na2SiO3. The study involved an investigation of the workability, mechanical properties, bond strength, and dry shrinkage of the mortars, employing different percentages of SL and FA. At the same time, TGA, XRD, MIP, and SEM were applied to investigate the chemical composition and microstructure of the binder gel phase. The results showed that when the SL content reached 40% and the FA content was 30%, the repair performance of mortar was much better than numerous repair materials, with an excellent compressive strength (94.0 MPa), flexural strength (11.0 MPa), and bond strength (6.33 MPa). As such, increasing the SL and FA contents seemed to have a positive influence on dry shrinkage and mechanical strengths. Additionally, when the FA content was 30%, the incorporation of SL was found to promote EFNS hydrolysis, and the hydration could directly generate hydrotalcite, which was beneficial to decreasing drying shrinkage at 28 d. The present study provides a theoretical foundation for the application of EFNS-based geopolymers in repair materials

Physical Activity-Related Injury and Its Associated Factors among Middle School Students in Southern China

Physical activity (PA) promotion is beneficial to gain and maintain optimal health, but might increase risks for physical activity-related injury (PARI). This cross-sectional study aimed to investigate the incidence rate and identify risk factors of PARI among Chinese middle school students. Selected via the method of cluster random sampling, students graded 7–8 (junior) and 10–11 (senior) from five middle schools (aged from 10 to 18 years old) in Shantou were invited to participate in the survey. Information on socio-demography, PA involvement, sleep duration, individual safety awareness and exercise behavior, and PARI experiences in the past 12 month was collected. Multivariate logistic regression model was performed to estimate the risk factors of PARI. A total of 3082 participants completed the valid questionnaires, with an overall incidence rate of 25.1%. Boys, junior school students, sports team members, and those with lower safety awareness, living with single parent, and without any chronic conditions were at higher risks for PARI. Moreover, exercising on wet floor or with illness frequently would also be more likely to experience injury, especially those with at least 120 min per day. In conclusion, PARI was prevalent among middle school students in southern China. The above data provide insights that were focused and effective actions should be taken to prevent school-aged adolescents from PARI and maximize the benefits of PA

Fabrication of the Hierarchical HZSM-5 Membrane with Tunable Mesoporosity for Catalytic Cracking of n-Dodecane

Hierarchical HZSM-5 membranes were prepared on the inner wall of stainless steel tubes, using amphiphilic organosilane (TPOAC) and mesitylene (TMB) as a meso-porogen and a swelling agent, respectively. The mesoporosity of the HZSM-5 membranes were tailored via formulating the TPOAC/Tetraethylorthosilicate (TPOAC/TEOS) ratio and TMB/TPOAC ratio, in synthesis gel, and the prepared membranes were systematically characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption–desorption, N2 permeation, inductively coupled plasma (ICP), in situ fourier transform infrared (FT-IR), ammonia temperature-programmed desorption (NH3-TPD), etc. It was found that the increase of the TPOAC/TEOS ratio promoted a specific surface area and diffusivity of the HZSM-5 membranes, as well as decreased acidity; the increase of the TMB/TPOAC ratios led to an enlargement of the mesopore size and diffusivity of the membranes, but with constant acid properties. The catalytic performance of the prepared HZSM-5 membranes was tested using the catalytic cracking of supercritical n-dodecane (500 °C, 4 MPa) as a model reaction. The hierarchical membrane with the TPOAC/TEOS ratio of 0.1 and TMB/TPOAC ratio of 2, exhibited superior catalytic performances with the highest activity of up to 13% improvement and the lowest deactivation rate (nearly a half), compared with the microporous HZSM-5 membrane, due to the benefits of suitable acidity, together with enhanced diffusivity of n-dodecane and cracking products