Elevated temperature as a result of global climate warming, either in form of sudden heatwave (heat shock) or prolonged warming, has profound effects on the growth and development of plants. However, ...how plants differentially respond to these two forms of elevated temperatures is largely unknown. Here we have therefore performed a comprehensive comparison of multi-level responses of Arabidopsis leaves to heat shock and prolonged warming.
The plant responded to prolonged warming through decreased stomatal conductance, and to heat shock by increased transpiration. In carbon metabolism, the glycolysis pathway was enhanced while the tricarboxylic acid (TCA) cycle was inhibited under prolonged warming, and heat shock significantly limited the conversion of pyruvate into acetyl coenzyme A. The cellular concentration of hydrogen peroxide (H
O
) and the activities of antioxidant enzymes were increased under both conditions but exhibited a higher induction under heat shock. Interestingly, the transcription factors, class A1 heat shock factors (HSFA1s) and dehydration responsive element-binding proteins (DREBs), were up-regulated under heat shock, whereas with prolonged warming, other abiotic stress response pathways, especially basic leucine zipper factors (bZIPs) were up-regulated instead.
Our findings reveal that Arabidopsis exhibits different response patterns under heat shock versus prolonged warming, and plants employ distinctly different response strategies to combat these two types of thermal stress.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Cellulose-derived carbonaceous catalyst (CCC) was prepared and characterized.•CCC was active for the conversion of glucose and other carbohydrates into HMF.•CCC could be easily recycled and ...regenerated.•The mechanism for converting carbohydrates into HMF over CCC was proposed.
Three environmental-benign and low-cost carbon-based solid acid catalysts containing –SO3H, –COOH and phenolic –OH groups were prepared and used for the conversion of glucose into 5-hydroxymethylfurfural (HMF) in ionic liquid 1-butyl-3-methylimidazolium chloride (BMIMCl). The results demonstrated that cellulose-derived carbonaceous catalyst (CCC) possessed the highest catalytic activity, which resulted in 46.4% HMF yield at 160°C for only 15min. In addition, the reaction kinetics for the conversion of glucose into HMF over CCC was fitted with the first-order rate equation. The slightly-deactivated CCC after four successive reaction runs could be easily regenerated by a simple carbonization and sulfonation process. More gratifyingly, the combination of CCC and BMIMCl were confirmed to be suitable for converting other carbohydrates such as fructose, sucrose, maltose, cellobiose, starch and cellulose into HMF. Particularly, a plausible mechanism involving hydrolysis, isomerization and dehydration for the conversion of carbohydrates into HMF was also proposed.
Abstract
Most published newborn growth references are based on conventional monitoring data that usually included both low- and high-risk pregnancies. We sought to develop a set of neonatal growth ...standards constructed from only a large sample of low-risk pregnancies. A total of 24,375 naturally conceived singleton live births with gestational ages of 24–42 weeks were collected in 69 hospitals in thirteen Chinese cities between 2015 and 2018. Unhealthy infants or those with high-risk mother were excluded. Smoothed percentile curves of six anthropometric indicators were established using the Generalized Additive Model for Location, Scale and Shape. The 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentile references for birth weight, length, head circumference, weight/length, body mass index, and ponderal index were calculated for neonates with gestational ages of 24–42 weeks. This set of neonatal growth standards with six anthropometric indicators can provide more tools for growth and nutrition assessment and body proportionality in neonatal clinical practice. These standards might also help to show the differences between growth curves based on low-risk and mixed low- and high-risk pregnancies.
A green and efficient process was developed for the conversion of biomass-derived furfuryl alcohol to ethyl levulinate using eco-friendly solid acid catalysts (zeolites and sulfated oxides) in ...ethanol. Studies for optimizing the reaction conditions such as the substrate concentration, the reaction time, the temperature, and the catalyst loading dosage were performed. With SO42−/TiO2 as the catalyst, a high ethyl levulinate yield of 74.6 mol% was achieved using a catalyst load of 5 wt% at 398 K for 2.0 h. The catalyst recovered through calcination was found to maintain good catalytic activity (47.8 mol%) after three cycles, and it was easily reactivated by re-soaking in H2SO4 solution. Catalyst characterization was based on BET surface area, NH3-TPD, and elemental analysis techniques.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In the routine inspection process of railway catenary systems, the primary task is to find out the locations of various components accurately. The complex composition of the components in the ...catenary system and their large dimensional differences make the inspection of small components considerably difficult. Aiming at the problem of the difficulty in locating small components, a new locating method, named asymmetrically effective decoupled head-you only look once (AED-YOLO), for locating small components of the catenary has been proposed in this study. In this method, firstly, a small object detection layer has been added to improve the detection accuracy of the small-sized components such as fastener nuts and bracing wire. Secondly, to reduce missed and false detection errors of small components, the improved bidirectional feature pyramid network with high-order spatial interactions and recursive gated convolution has been used to fuse the features of different scales to further enhance the ability to detect small objects. Finally, an asymmetrically effective decoupled head has been proposed using different decoupled branches to decouple the classification and localization processes, thus further reducing the error in small-sized object classification and location. Experiments performed on the railway catenary dataset collected on-site show that the proposed localization method can efficiently improve detection accuracy, achieving a mean average precision of 93.5%. Thus, compared to the other methods, the proposed method can accurately locate small-sized components.
The quantitative estimation of the total interaction energy of a molecular system containing hydrogen bonds (H bonds) depends largely on how to identify H bonding. The conventional geometric criteria ...of H bonding are simple and convenient in application, but a certain amount of non-H bonding cases are also identified as H bonding. In order to investigate the wrong identification, we carry out a systematic calculation on the interaction energy of two water molecules at various orientation angles and distances using ab initio molecular dynamics method with the dispersion correction for the Becke-Lee-Yang-Parr (BLYP) functionals. It is shown that, at many orientation angles and distances, the interaction energies of the two water molecules exceed the energy criterion of the H bond, but they are still identified as H-bonded by the conventional "distance-angle" criteria. It is found that in these non-H bonding cases the wrong identification is mainly caused by short-range interaction between the two neighbouring water molecules. We thus propose that, in addition to the conventional distance and angle criteria of H bonding, the distance d(H···H) between the two neighbouring hydrogen atoms of the two water molecules should also be taken as a criterion, and the distance r(O···H) between the hydrogen atom of the H-bond donor molecule and the oxygen atom of the acceptor molecule should be restricted by a lower limit. When d(H···H) and r(O···H) are small (e.g., d(H···H) < 2.0 Å and r(O···H) < 1.62 Å), the repulsion between the two neighbouring atoms increases the total energy of the two water molecules dramatically and apparently weakens the binding of the water dimer. A statistical analysis and comparison of the numbers of the H bonds identified by using different criteria have been conducted on a Car-Parrinello ab initio molecular dynamics simulation with dispersion correction for a system of 64 water molecules at near-ambient temperature. They show that the majority of the H-bonds counted by using the conventional criteria combined with the d(H···H) criterion and the restriction of r(O···H) match what is identified by the binding energy criteria (e.g., E ≤ -10 kJ/mol), while some of them still have a binding energy that exceeds the energy criterion, indicating that the complicated quantum effects in H bonding can only be described by the three geometric parameters to a certain extent.
Microtubule catalyzes the mechanochemical cycle of kinesin, a kind of molecular motor, through its crucial roles in kinesin’s gating, ATPase and force-generation process. These functions of ...microtubule are realized through the kinesin-microtubule interaction. The binding site of kinesin on the microtubule surface is fixed. For most of the kinesin-family members, the binding site on microtubule is in the groove between
α
-tubulin and
β
-tubulin in a protofilament. The mechanism of kinesin searching for the appropriate binding site on microtubule is still unclear. Using the molecular dynamics simulation method, we investigate the interactions between kinesin-1 and the different binding positions on microtubule. The key non-bonded interactions between the motor domain and tubulins in kinesin’s different nucleotide-binding states are listed. The differences of the amino-acid sequences between
α
- and
β
-tubulins make kinesin-1 binding to the
α
–
β
groove much more favorable than to the
β
–
α
groove. From these results, a two-step mechanism of kinesin-1 to discriminate the correct binding site on microtubule is proposed. Most of the kinesin-family members have the conserved motor domain and bind to the same site on microtubule, the mechanism may also be shared by other family members of kinesin.
Kinesin-1 is a motor protein moving along a microtubule with its two identical motor heads dimerized by two neck linkers and a coiled-coil stalk. When both motor heads bind the microtubule, an ...internal strain is built up between the two heads, which is indispensable to ensure proper coordination of the two motor heads during kinesin-1’s mechanochemical cycle. The internal strain forms a tensile force along the neck linker that tends to unwind the neck coiled coil (NCC). Experiments showed that the kinesin-1’s NCC has a high antiunwinding ability compared with conventional coiled coils, which was mainly attributed to the enhanced hydrophobic pressure arising from the unconventional sequence of kinesin-1’s NCC. However, hydrophobic pressure cannot provide the shearing force which is needed to balance the tensile force on the interface between two helices. To find out the true origin of the mechanical stability of kinesin-1’s NCC, we perform a novel and detailed mechanical analysis for the system based on molecular dynamics simulation at an atomic level. We find that the needed shearing force is provided by a buckle structure formed by two tyrosines which form effective steric hindrance in the presence of tensile forces. The tensile force is balanced by the tensile direction component of the contact force between the two tyrosines which forms the shearing force. The hydrophobic pressure balances the other component of the contact force perpendicular to the tensile direction. The antiunwinding strength of NCC is defined by the maximum shearing force, which is finally determined by the hydrophobic pressure. Kinesin-1 uses residues with plane side chains, tryptophans and tyrosines, to form the hydrophobic center and to shorten the interhelix distance so that a high antiunwinding strength is obtained. The special design of NCC ensures exquisite cooperation of steric hindrance and hydrophobic pressure that results in the surprising mechanical stability of NCC.
Background: The goal of this study was to evaluate plasma D-dimer as a diagnostic marker for exclusion of suspected aortic dissection (AD). Methods: Two-hundred and sixty suspected AD patients were ...enrolled, including acute AD, n=107; chronic AD, n=17; acute myocardial infarction (AMI), n=70; pulmonary embolism (PE), n=18; non-ST elevation myocardial infarction (NSTEMI), n=28; and unstable angina (UA), n=20. All patients had D-dimer testing performed (Roche Diagnostics GmbH) immediately following admission. Results: The D-dimer concentrations in both the acute AD group median: 3.47; 95% confidence interval (CI): 2.43–4.50 μg/mL and chronic AD group (median: 1.09; 95% CI: 0.36–3.81 μg/mL) were significantly higher than those in patients in the AMI, NSTEMI and UA groups (p=0.000), but not when compared to the PE group. One (0.8%) patient was identified in the acute AD group who presented with a low D-dimer value (0.04 μg/mL), indicating the existence of intramural hematoma as demonstrated by CT. Conclusions: D-dimer may be used as a potential marker for suspected AD, with high sensitivity of up to 99.2% (1/124). Regardless of the cut-off threshold selected, the sensitivity of D-dimer was unable to reach 100%. Further examinations, including imaging technology, were necessary to diagnose the suspected AD patients who had negative D-dimer result. Clin Chem Lab Med 2010;48:1733–7.
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