Summary
The continuing nitrogen (N) deposition observed worldwide alters ecosystem nutrient cycling and ecosystem functioning. Litter decomposition is a key process contributing to these changes, but ...the numerous mechanisms for altered decomposition remain poorly identified.
We assessed these different mechanisms with a decomposition experiment using litter from four abundant species (Achnatherum sibiricum, Agropyron cristatum, Leymus chinensis and Stipa grandis) and litter mixtures representing treatment‐specific community composition in a semi‐arid grassland under long‐term simulation of six different rates of N deposition.
Decomposition increased consistently with increasing rates of N addition in all litter types. Higher soil manganese (Mn) availability, which apparently was a consequence of N addition‐induced lower soil pH, was the most important factor for faster decomposition. Soil C : N ratios were lower with N addition that subsequently led to markedly higher bacterial to fungal ratios, which also stimulated litter decomposition.
Several factors contributed jointly to higher rates of litter decomposition in response to N deposition. Shifts in plant species composition and litter quality played a minor role compared to N‐driven reductions in soil pH and C : N, which increased soil Mn availability and altered microbial community structure. The soil‐driven effect on decomposition reported here may have long‐lasting impacts on nutrient cycling, soil organic matter dynamics and ecosystem functioning.
We present strategies to tune the redox properties of polyoxometalate clusters to enhance the electron‐coupled proton‐buffer‐mediated water splitting process, in which the evolution of hydrogen and ...oxygen can occur in different forms and is separated in time and space. By substituting the heteroatom template in the Keggin‐type polyoxometalate cluster, H6ZnW12O40, it is possible to double the number of electrons and protonation in the redox reactions (from two to four). This increase can be achieved with better matching of the energy levels as indicated by the redox potentials, compared to the ones of well‐studied H3PW12O40 and H4SiW12O40. This means that H6ZnW12O40 can act as a high‐performance redox mediator in an electrolytic cell for the on‐demand generation of hydrogen with a high decoupling efficiency of 95.5 % and an electrochemical energy efficiency of 83.3 %. Furthermore, the H6ZnW12O40 cluster also exhibits an excellent cycling behaviour and redox reversibility with almost 100 % H2‐mediated capacity retention during 200 cycles and a high coulombic efficiency >92 % each cycle at 30 mA cm−2.
The molecular structure of keggin‐type tungsten polyoxometalates (POMs) were tuned with different heteroatoms to modify their redox properties. Compared to the two electrons of well‐studied H3PW12O40 and H4SiW12O40, H6ZnW12O40 exhibits double reversible electrons with protonation in the redox reactions and the more desirable redox potentials, which enhance its ECPB performance (see scheme).
Huddling is highly evolved as a cooperative behavioral strategy for social mammals to maximize their fitness in harsh environments. Huddling behavior can change psychological and physiological ...responses. The coevolution of mammals with their microbial communities confers fitness benefits to both partners. The gut microbiome is a key regulator of host immune and metabolic functions. We hypothesized that huddling behavior altered energetics and thermoregulation by shaping caecal microbiota in small herbivores. Brandt's voles (Lasiopodomys brandtii) were maintained in a group (huddling) or as individuals (separated) and were exposed to warm (23 ± 1 °C) and cold (4 ± 1 °C) air temperatures (T
).
Voles exposed to cold T
had higher energy intake, resting metabolic rate (RMR) and nonshivering thermogenesis (NST) than voles exposed to warm T
. Huddling voles had lower RMR and NST than separated voles in cold. In addition, huddling voles had a higher surface body temperature (T
), but lower core body temperature (T
) than separated voles, suggesting a lower set-point of T
in huddling voles. Both cold and huddling induced a marked variation in caecal bacterial composition, which was associated with the lower T
. Huddling voles had a higher α and β-diversity, abundance of Lachnospiraceae and Veillonellaceae, but lower abundance of Cyanobacteria, Tenericutes, TM7, Comamonadaceae, and Sinobacteraceae than separated voles. Huddling or cold resulted in higher concentrations of short-chain fatty acids (SCFAs), particularly acetic acid and butyric acid when compared to their counterparts. Transplantation of caecal microbiota from cold-separated voles but not from cold-huddling voles induced significant increases in energy intake and RMR compared to that from warm-separated voles.
These findings demonstrate that the remodeling of gut microbiota, which is associated with a reduction in host T
, mediates cold- and huddling-induced energy intake and thermoregulation and therefore orchestrates host metabolic and thermal homeostasis. It highlights the coevolutionary mechanism of host huddling and gut microbiota in thermoregulation and energy saving for winter survival in endotherms.
Herein, ruthenium (Ru) nanoparticles were anchored on carbon nanotubes (Ru/CNTs) functionalized as catalyst cathodes for non-aqueous Li–CO2 cells. For cycling tests through a low cut-off capacity ...(100 mA h g−1), the origin of battery deterioration resulted from the accumulation of Li2CO3 discharging products on catalytic surfaces, identical to the observations in previous studies. However, the Li–CO2 cells in this work showed a sudden death within several cycles of high cut-off capacity (500 mA h g−1), and no Li2CO3 residues were investigated on the cathode. In contrast, Li dendrites and passivation materials (LiOH and Li2CO3) were generated on Li anodes upon cycling at a limited capacity of 500 mA h g−1, which dominantly contributed to the battery degradation. A Li foil-replacement method was adopted to make the Ru/CNT cathode perform continuous 100 cycles under a cut-off capacity of 500 mA h g−1. These results indicate that not only Li2CO3 residues blocked on the active sites of the cathode but also Li dendrites and passivation materials produced on the anode caused Li–CO2 battery deterioration. Moreover, in the present work, a carbon thin film was deposited on Li metal (C/Li) by a sputtering system for suppressing the dendrite formation upon cycling and promoting the defense of the H2O attack from the electrolyte disintegration. The Li–CO2 cell with a Ru/CNT catalyst and a C/Li anode revealed an improved electrochemical stability of 115 cycles at a limited capacity of 500 mA h g−1. This proto strategy provided a significant research direction focusing on Li anodes for elevating the Li–CO2 battery durability.
The transformations that allow the direct removal of hydrogen from their corresponding saturated counterparts by the dehydrogenative strategy are a dream reaction that has remained largely ...underexplored. In this report, a straightforward and robust cobaloxime-catalyzed photochemical dehydrogenation strategy
via
intramolecular HAT is described for the first time. The reaction proceeds through an intramolecular radical translocation followed by the cobalt assisted dehydrogenation without needing any other external photosensitizers, noble-metals or oxidants. With this approach, a series of valuable unsaturated compounds such as α,β-unsaturated amides, enamides and allylic and homoallylic sulfonamides were obtained in moderate to excellent yields with good chemo- and regioselectivities, and the synthetic versatility was demonstrated by a range of transformations. And mechanistic studies of the method are discussed.
The dehydrogenative reactions proceeded through selective 1,
n
-hydrogen atom transfer (
n
= 5-7) for remote C-H activation by cobaloxime catalysis.
Summary
Differences in litter quality and in soil microbial community composition can influence the litter decomposition and ‘home‐field advantage’ (HFA). However, our knowledge about the relative ...role of litter and soil characteristics on litter decomposition and HFA effects is still limited, especially under long‐term N deposition.
We collected soil and two types of litter (monospecific and mixed species litter) from five replicate plots from a long‐term N deposition field experiment with seven N addition treatments (0, 2, 5, 10, 15, 20, 50 g N m−2 year−1). We examined the effects of N addition on litter quality and soil characteristics. We then carried out a three‐pronged microcosm decomposition experiment with (i) litter from different N addition treatments decomposed on a standard field soil; (ii) standard litter decomposed on soils from the different N addition treatments; and (iii) litter decomposed on soil from the same N addition treatment plot.
Decomposition of litter on standard soil was influenced strongly by the N addition treatment, but did not consistently decrease or increase with increasing N addition rates. Instead, decomposition of standard litter on soils collected from different N addition treatments decreased with increasing rates of N addition. Decomposition of litter on soil collected from the same plot increased with increasing N addition rates. Soil characteristics explained more of the variation in litter decomposition than litter characteristics.
There was a clear HFA effect for litter decomposition, both from a litter and from a soil perspective. HFA effects increased when the dissimilarity in litter quality (N content and C : N ratio) increase among the different N addition treatments and the soil effect was strongest at high N addition rates.
N addition influenced litter decomposition by changing both litter and soil characteristics. Importantly, N addition decreased the capability of soils to decompose litter and it increased the HFA effect indicating that soils decomposed local litter better than other litter, due to specialization in soil communities. Nitrogen deposition is an important threat to ecosystems worldwide and our study emphasizes that ecosystem functions such as decomposition can be greatly influenced by these global changes.
A lay summary is available for this article.
Lay Summary
Four undescribed sesquiterpenoids, lemneolemnanes A-D (
-
), have been isolated from the marine soft coral
sp. The absolute configurations of the stereogenic carbons of
-
were determined by ...single-crystal X-ray crystallographic analysis. Compounds
and
are epimers at C-3 and have an unusual skeleton with a formyl group on C-6. Compound
possesses an uncommonly rearranged carbon skeleton, while
has a 6/5/5 tricyclic system. Compound
showed significant anti-Alzheimer's disease (AD) activity in a humanized
AD pathological model.
We applied Simmons-Balluffi methods, positron measurements, and neutron diffraction to estimate the vacancy of CoCrFeNi and CoCrFeMnNi high-entropy alloys (HEAs) using Cu as a benchmark. The ...corresponding formation enthalpies and associated entropies of the HEAs and Cu were calculated. The vacancy-dependent effective free volumes in both CoCrFeNi and CoCrFeMnNi alloys are greater than those in Cu, implying the easier formation of vacancies by lattice structure relaxation of HEAs at elevated temperatures. Spatially resolved synchrotron X-ray measurements revealed different characteristics of CoCrFeNi and CoCrFeMnNi HEAs subjected to quasi-equilibrium conditions at high temperatures. Element-dependent behavior revealed by X-ray fluorescence (XRF) mapping indicates the effect of Mn on the Cantor Alloy.
Escherichia coli BL21 (DE3) is an excellent and widely used host for recombinant protein production. Many variant hosts were developed from BL21 (DE3), but improving the expression of specific ...proteins remains a major challenge in biotechnology. In this study, we found that when BL21 (DE3) overexpressed glucose dehydrogenase (GDH), a significant industrial enzyme, severe cell autolysis was induced. Subsequently, we observed this phenomenon in the expression of 10 other recombinant proteins. This precludes a further increase of the produced enzyme activity by extending the fermentation time, which is not conducive to the reduction of industrial enzyme production costs. Analysis of membrane structure and messenger RNA expression analysis showed that cells could underwent a form of programmed cell death (PCD) during the autolysis period. However, blocking three known PCD pathways in BL21 (DE3) did not completely alleviate autolysis completely. Consequently, we attempted to develop a strong expression host resistant to autolysis by controlling the speed of recombinant protein expression. To find a more suitable protein expression rate, the high‐ and low‐strength promoter lacUV5 and lac were shuffled and recombined to yield the promoter variants lacUV5‐1A and lac‐1G. The results showed that only one base in lac promoter needs to be changed, and the A at the +1 position was changed to a G, resulting in the improved host BL21 (DE3‐lac1G), which resistant to autolysis. As a consequence, the GDH activity at 43 h was greatly increased from 37.5 to 452.0 U/ml. In scale‐up fermentation, the new host was able to produce the model enzyme with a high rate of 89.55 U/ml/h at 43 h, compared to only 3 U/ml/h achieved using BL21 (DE3). Importantly, BL21 (DE3‐lac1G) also successfully improved the production of 10 other enzymes. The engineered E. coli strain constructed in this study conveniently optimizes recombinant protein overexpression by suppressing cell autolysis, and shows great potential for industrial applications.
The high‐ and low‐strength promoter lacUV5 and lac were shuffled and recombined for controlling the speed of recombinant protein expression. Results demonstrate that the new strain BL21 (DE3‐lac1G) can effectively avoid cell lysis and successfully improved the production of over 10 enzymes, which will make it a popular host for protein production, especially for proteins requiring a longer fermentation time or maturation with post‐processing.
Over the past years, vascular diseases have continued to threaten human health and increase financial burdens worldwide. Transplantation of allogeneic and autologous blood vessels is the most ...convenient treatment. However, it could not be applied generally due to the scarcity of donors and the patient's condition. Developments in tissue engineering are contributing greatly with regard to this urgent need for blood vessels. Tissue engineering-derived blood vessels are promising alternatives for patients with aortic dissection/aneurysm. The aim of this review is to show the importance of advances in biomaterials development for the treatment of vascular disease. We also provide a comprehensive overview of the current status of tissue reconstruction from stem cells and transplantable cellular scaffold constructs, focusing on the combination of stem cells and tissue engineering for blood vessel regeneration and vascular disease treatment.
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