The emerging inverse electron demand Diels-Alder (IEDDA) reaction stands out from other bioorthogonal reactions by virtue of its unmatchable kinetics, excellent orthogonality and biocompatibility. ...With the recent discovery of novel dienophiles and optimal tetrazine coupling partners, attention has now been turned to the use of IEDDA approaches in basic biology, imaging and therapeutics. Here we review this bioorthogonal reaction and its promising applications for live cell and animal studies. We first discuss the key factors that contribute to the fast IEDDA kinetics and describe the most recent advances in the synthesis of tetrazine and dienophile coupling partners. Both coupling partners have been incorporated into proteins for tracking and imaging by use of fluorogenic tetrazines that become strongly fluorescent upon reaction. Selected notable examples of such applications are presented. The exceptional fast kinetics of this catalyst-free reaction, even using low concentrations of coupling partners, make it amenable for
in vivo
radiolabelling using pretargeting methodologies, which are also discussed. Finally, IEDDA reactions have recently found use in bioorthogonal decaging to activate proteins or drugs in gain-of-function strategies. We conclude by showing applications of the IEDDA reaction in the construction of biomaterials that are used for drug delivery and multimodal imaging, among others. The use and utility of the IEDDA reaction is interdisciplinary and promises to revolutionize chemical biology, radiochemistry and materials science.
The emerging inverse electron demand Diels-Alder (IEDDA) reaction stands out from other bioorthogonal reactions by virtue of its unmatchable kinetics, excellent orthogonality and biocompatibility.
Background
Several previous researches had found artery stiffness associated skeletal muscle mass, but not considering muscle strength and physical performance, which also were compositions of ...sarcopenia. This study aims to reveal the relationship of artery stiffness and sarcopenia using the Asian Working Group for Sarcopenia criteria.
Methods
Study was performed on 1002 Chinese community dwelling participants aged ≥65 years from November 2016 to March 2017. Body composition, muscle strength, physical performance, and brachial-ankle pulse wave velocity (baPWV) considering as artery stiffness index were measured.
Results
In multiple regression analysis, baPWV was associated with handgrip (β=−0.13, P=0.04) and Relative skeletal muscle mass index (ASM/Ht
2
) (β=−0.02, P<0.01), but not with 4-meter velocity (P=0.21). Multiple logistic regression analysis showed that 1-SD (3.50m/s) increased in baPWV was still associated with a 11% (CI, 4%–20%; P<0.01) higher odds of being sarcopenia. In the gender subgroup analysis, the relationship of baPWV and sarcopenia remain significant in men (OR, 1.23; 95% CI, 1.07–1.42, P<0.01), but not in women (P=0.07).
Conclusions
High brachial-ankle pulse wave velocity is associated with sarcopenia in Chinese community-dwelling elderly, with gender differences.
HUBS: Hot Universe Baryon Surveyor Cui, W.; Chen, L.-B.; Gao, B. ...
Journal of low temperature physics,
04/2020, Letnik:
199, Številka:
1-2
Journal Article
Recenzirano
Hot Universe Baryon Surveyor (HUBS) is proposed in China as a major X-ray mission for the next decade. It is designed to be highly focused scientifically, with two primary objectives: (1) detecting ...X-ray emission from hot baryons in intergalactic medium and circumgalactic medium (CGM), and characterizing their physical and chemical properties; (2) studying, based on the observations, the accretion and feedback processes that are thought to be highly relevant to the heating and chemical enrichment of the baryons in the CGM. Because of very low densities, the signal is expected to be very weak and thus technically difficult to detect. On the other hand, the spectrum of the emission is expected to be line rich, so it would be effective for detecting the hot baryons in bright emission lines. For that, an instrument with high spectral resolution, large effective area and large field of view (FoV) would be required. HUBS will couple a TES-based X-ray imaging spectrometer to a large FoV X-ray telescope to satisfy these requirements. A preliminary design of HUBS is presented.
The effects of land use change on soil carbon stocks are of concern in the context of international policy agendas on greenhouse gas emissions mitigation. This paper reviews the literature for the ...influence of land use changes on soil C stocks and reports the results of a meta analysis of these data from 74 publications. The meta analysis indicates that soil C stocks decline after land use changes from pasture to plantation (−10%), native forest to plantation (−13%), native forest to crop (−42%), and pasture to crop (−59%). Soil C stocks increase after land use changes from native forest to pasture (+ 8%), crop to pasture (+ 19%), crop to plantation (+ 18%), and crop to secondary forest (+ 53%). Wherever one of the land use changes decreased soil C, the reverse process usually increased soil carbon and vice versa. As the quantity of available data is not large and the methodologies used are diverse, the conclusions drawn must be regarded as working hypotheses from which to design future targeted investigations that broaden the database. Within some land use changes there were, however, sufficient examples to explore the role of other factors contributing to the above conclusions. One outcome of the meta analysis, especially worthy of further investigation in the context of carbon sink strategies for greenhouse gas mitigation, is that broadleaf tree plantations placed onto prior native forest or pastures did not affect soil C stocks whereas pine plantations reduced soil C stocks by 12–15%.
The majority of the Earth's terrestrial carbon is stored in the soil. If anthropogenic warming stimulates the loss of this carbon to the atmosphere, it could drive further planetary warming. Despite ...evidence that warming enhances carbon fluxes to and from the soil, the net global balance between these responses remains uncertain. Here we present a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. Our empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 ± 30 petagrams of carbon to 203 ± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 ± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12-17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in our estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbon-climate feedback that could accelerate climate change.
Aims
The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama transmits the bacterium ‘Candidatus Liberibacter asiaticus’ (Las), which causes citrus huanglongbing (HLB) disease. Although many ...studies have been conducted on the biology of ACP on different host plants, few have taken the plant, Las bacteria and the vector insect within one context to evaluate the effects of Las on the fitness of ACP under field conditions. Understanding the relationship between Las and ACP is critical for both ACP and HLB disease management.
Methods and Results
We estimated the development and survival of ACP immatures, the longevity and fecundity of ACP female adults in four treatments (Las‐positive or ‐negative ACP on Las‐infected and ‐free citrus plants). Las‐positive ACP immatures developed significantly faster on Las‐infected citrus than those on Las‐free plants. The fecundity and longevity of Las‐positive female adults were also greater, or longer on Las‐infected citrus shoots, whereas the survival of Las‐positive immatures was significantly lower on Las‐infected citrus shoots, compared to those that developed on Las‐free plants. Similarly, the intrinsic rate of population increase (rm) was highest (0·1404) when Las‐positive ACP fed on Las‐infected citrus shoots and the lowest (0·1328) when the Las‐negative ACP fed on Las‐free citrus shoots.
Conclusions
Both the Las infection in ACP and citrus plants had obvious effects on the biology of ACP. When compared to the Las infection in ACP insects, the Las infection in citrus shoots had a more significant effect on the fitness of ACP.
Significance and Impact of the Study
To efficiently prevent the occurrence and spread of HLB disease, it is critical to understand the ecological basis of vector outbreaks and disease incidence, especially under field conditions. Thus, this study has increased our understanding of the epidemiology of HLB transmitted by psyllids in nature.
Magnetic reconnection is a fundamental process in collisionless space plasma environment, and plasma waves relevant to the kinetic interactions can have a significant impact on the multiscale ...behavior of reconnection. Here, we present Magnetospheric Multiscale (MMS) observations during an encounter of an X line of symmetric magnetic reconnection in the magnetotail. The X line is characterized by reversals of ion and electron jets and electromagnetic fields, agyrotropic electron velocity distribution functions (VDFs), and an electron‐scale current sheet. MMS observe large‐amplitude nonlinear upper‐hybrid (UH) waves on both sides of the neutral line, and the wave amplitudes have highly localized distribution along the normal direction. The inbound meandering electrons drive the UH waves, releasing the free energy stored from the reconnection electric field along the meandering trajectories. The interaction between the meandering electrons and the UH waves may modify the balance of the reconnection electric field around the X line.
Plain Language Summary
The electron‐scale kinetic physics in the electron diffusion region (EDR) controls how magnetic field lines break and reconnect. Electron crescent, an indicator of EDR, can drive high‐frequency electrostatic waves around EDR. For the first time, the upper‐hybrid (UH) waves are observed on both sides of the X line and we show the direct association between the UH waves and the reconnection electric field. The strong wave‐electron interaction can change the electron‐scale dynamics and may modify the reconnection electric field. This study demonstrates that the UH waves may play an important role in controlling the reconnection rate.
Key Points
Large amplitude nonlinear upper‐hybrid (UH) waves are observed on both inflow sides of an X line
The UH waves are driven by the inbound meandering electrons
The UH waves may dissipate a significant part of the meandering electron energy gained from the reconnection electric field
The quantitative analysis of iron ore by laser-induced breakdown spectroscopy (LIBS) is usually complicated due to nonlinear self-absorption and matrix effects. To overcome this challenge, a hybrid ...sparse partial least squares (SPLS) and least-squares support vector machine (LS-SVM) model was proposed to analyze the content of total iron (TFe) and oxides SiO
2
, Al
2
O
3
, CaO, and MgO in iron ore. In this study, 24 samples were used for calibration and 12 for prediction. Sparse partial least squares was used for variable selection and establishing the multilinear regression model between spectral data and concentrations; LS-SVM was used to fit the residual errors of the SPLS regression model to compensate for the nonlinear effects. The model parameters were determined by using the tenfold cross-validation (CV) method. With the hybrid model, the root-mean-square-error of prediction (RMSEP) values of TFe, SiO
2
, Al
2
O
3
, CaO, and MgO were 0.6242, 0.3569, 0.0456, 0.0962, and 0.2157 wt%, respectively. The results showed that the hybrid model yielded better performance than only the conventional SPLS or LS-SVM model. This study demonstrated that the hybrid model is a competitive data processing method for iron ore analysis using LIBS.
A hybrid sparse partial least squares and least-squares support vector machine model was proposed to improve the accuracy of iron ore analysis using LIBS.
Summary
Breeding for good meat quality performance while maintaining large body size and desirable carcass traits has been the major challenge for modern swine selective breeding. To address this ...goal, in the present work we studied five related populations produced by two commercial breeds (Berkshire and Duroc) and two Chinese breeds (Licha black pig and Lulai black pig). A single‐trait GWAS performed on 20 body size and carcass traits using a self‐developed China Chip‐1 porcine SNP50K BeadChip identified 11 genome‐wide significant QTL on nine chromosomes and 22 suggestive QTL on 15 chromosomes. For the 11 genome‐wide significant QTL, eight were detected in at least two populations, and the rest were population‐specific and only mapped in Shanxia black pig. Most of the genome‐wide significant QTL were pleiotropic; for example, the QTL around 75.65 Mb on SSC4 was associated with four traits at genome‐wide significance level. After screening the genes within 50 kb of the top SNP for each genome‐wide significant QTL, NR6A1 and VRTN were chosen as candidate genes for vertebrae number; PLAG1 and BMP2 were identified as candidate genes for body size; and MC4R was the strong candidate gene for body weight. The four genes have been reported as candidates for thoracic vertebrae number, lumbar vertebrae number, carcass length and body weight respectively in previous studies. The effects of VRTN on thoracic vertebrae number, carcass length and body length have been verified in Shanxia black pig. Therefore, the VRTN genotype could be used in gene‐assisted selection, and this could accelerate genetic improvement of body size and carcass traits in Shanxia black pig.
Kinetic‐scale magnetic dips (KSMDs), with a significant depression in magnetic field strength, and scale length close to and less than one proton gyroradius, were reported in the turbulent plasmas ...both in recent observation and numerical simulation studies. These KSMDs likely play important roles in energy conversion and dissipation. In this study, we present observations of the KSMDs that are labeled whistler mode waves, electrostatic solitary waves, and electron cyclotron waves in the magnetosheath. The observations suggest that electron temperature anisotropy or beams within KSMD structures provide free energy to generate these waves. In addition, the occurrence rates of the waves are higher in the center of the magnetic dips than at their edges, implying that the KSMDs might be the origin of various kinds of waves. We suggest that the KSMDs could provide favorable conditions for the generation of waves and transfer energy to the waves in turbulent magnetosheath plasmas.
Plain Language Summary
The Earth's magnetosheath is a turbulent plasma environment where energy conversion, particle acceleration, and mass and momentum transport take place. Many of these key processes involve kinetic‐scale physics. However, in‐depth studies from previous missions are limited by their lower spacecraft data resolution. The recent Magnetospheric Multiscale (MMS) mission provides us with a large amount of high‐temporal cadence data for studying kinetic‐scale physics in the magnetosheath. In this study, we report whistler mode waves, electrostatic solitary waves and electron cyclotron waves within kinetic‐scale magnetic dips (KSMDs) that can be generated in the turbulent magnetosheath. These waves could be excited by electron temperature anisotropy or beams. As is well known, plasma waves are important processes in converting energy, accelerating and scattering electrons and ions, and modifying the distributions of charged particles. If plasma instabilities develop within the KSMDs, the resulting waves could absorb free energy from plasma particles and may propagate out of the KSMDs. Thus, our discoveries could significantly advance the understanding of energy conversion and dissipation for kinetic‐scale turbulence. This study provides a new reference not only for observations in space physics but also for related basic plasma theories and numerical simulations.
Key Points
MMS observations reveal KSMDs coupled with whistler mode waves, electrostatic solitary waves, and electron cyclotron waves
These waves are excited by different plasma distributions, and the ESWs could affect the electron distributions in kinetic scale
Statistical results indicate that the KSMDs in the magnetosheath are a possible origin for various kinds of waves
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