Formation of forest gaps accelerates C,N and P release from foliar litter during 4 years of decomposition in an alpine forest

High-latitude boreal and arctic surface/inland waters contain sizeable reservoirs of dissolved organic matter (DOM) and trace elements (TE), which are subject to seasonal freezing. Specifically, shallow ponds and lakes in the permafrost zone often freeze solid, which can lead to transformations in the colloidal and dissolved fractions of DOM and TE. Here, we present results from experimental freeze-thaw cycles using iron (Fe)- and DOM-rich water from thaw ponds situated in Stordalen and Storflaket palsa mires in northern Sweden. After ten cycles of freezing, 85% of Fe and 25% of dissolved organic carbon (DOC) were removed from solution in circumneutral fen water (pH 6.9) but a much smaller removal of Fe and DOC (< 7%) was found in acidic bog water (pH 3.6). This removal pattern was consistent with initial supersaturation of fen water with respect to Fe hydroxide and a lack of supersaturation with any secondary mineral phase in the bog water. There was a nearly two- to threefold increase in the low-molecular-weight (LMW) fraction of organic carbon (OC) and several TEs caused by the repeated freeze-thaw cycles. Future increases in the freeze-thaw frequency of surface waters with climate warming may remove up to 25% of DOC in circumneutral organic-rich waters. Furthermore, an increase of LMW OC may result in enhanced carbon dioxide losses from aquatic ecosystems since this fraction is potentially more susceptible to biodegradation.     

A Plausible Microtubule-Based Mechanism for Cell Division Orientation in Plant Embryogenesis

1. Download high-res image (203KB)
2. Download full-size image

     

Extraction and identification of the chyme proteins in the digestive tract of growing pigs

This study aimed to explore the rule of degradation of dietary proteins by identifying chyme proteins in different segments of the digestive tract of growing pigs, using proteomics techniques. Six growing pigs were fed a corn-soybean meal-based diet for 7 days. The feedstuff and chyme proteins were separately extracted and separated with SDS-PAGE. 2D LCMS/MS combined with protein database searching identified 1,513 proteins in different segments of the gastrointestinal tract, the number of identified exogenous proteins gradually decline from the stomach to colon, with large amounts in the duodenum to the large intestine. More corn proteins than soybean proteins were identified both in the feedstuff and chyme, and these were significantly decreased after digestion in the stomach. More membrane proteins than non-membrane proteins were identified in whole digestive tract. These results regarding the profiles of chyme proteins in different segments of the gastrointestinal tract would provide useful information for optimizing feed formula in pigs.     

Doped Copper Phthalocyanine via an Aqueous Solution Process for Normal and Inverted Perovskite Solar Cells

Great efforts toward developing novel and efficient hole‐transporting materials are needed to further improve the device efficiency and enhance the cell stability of perovskite solar cells (PSCs). The poor film conductivity and the low carrier mobility of organic small‐molecule‐based hole‐transporting materials restrict their application in PSCs. This study develops an efficient and stable hole‐transporting material, tetrafluorotetracyanoquinodimethane (F₄‐TCNQ)‐doped copper phthalocyanine‐3,4′,4′′,4′′′‐tetra‐sulfonated acid tetra sodium salt (TS‐CuPc) via a solution process, in planar structure PSCs. The p‐type‐doped TS‐CuPc film demonstrates improved film conductivity and hole mobility owing to the strong electron affinity of F₄‐TCNQ. By the F₄‐TCNQ tailoring, the composite film gives the highest occupied molecular orbital level as high as 5.3 eV, which is beneficial for hole extraction. In addition, the aqueous solution processed TS‐CuPc:F₄‐TCNQ precursor is almost neutral with good stability for avoiding the electrode erosion. As a result, the fabricated PSCs employing TS‐CuPc:F₄‐TCNQ as the hole‐transporting material exhibit a power conversion efficiency of 16.14% in a p–i–n structure and 20.16% in an n–i–p structure, respectively. The developed organic small molecule of TS‐CuPc provides the diversification of hole‐transporting materials in planar PSCs.     

YTH Domain: A Family of N6-methyladenosine (m6A) Readers

Like protein and DNA, different types of RNA molecules undergo various modifications. Accumulating evidence suggests that these RNA modifications serve as sophisticated codes to mediate RNA behaviors and many important biological functions. N⁶-methyladenosine (m⁶A) is the most abundant internal RNA modification found in a variety of eukaryotic RNAs, including but not limited to mRNAs, tRNAs, rRNAs, and long non-coding RNAs (lncRNAs). In mammalian cells, m⁶A can be incorporated by a methyltransferase complex and removed by demethylases, which ensures that the m⁶A modification is reversible and dynamic. Moreover, m⁶A is recognized by the YT521-B homology (YTH) domain-containing proteins, which subsequently direct different complexes to regulate RNA signaling pathways, such as RNA metabolism, RNA splicing, RNA folding, and protein translation. Herein, we summarize the recent progresses made in understanding the molecular mechanisms underlying the m⁶A recognition by YTH domain-containing proteins, which would shed new light on m⁶A-specific recognition and provide clues to the future identification of reader proteins of many other RNA modifications.     

Mapping Nonfullerene Acceptors with a Novel Wide Bandgap Polymer for High Performance Polymer Solar Cells

A new weak electron‐deficient building block, bis(2‐ethylhexyl) 2,5‐bis(5‐bromothiophen‐2‐yl) thieno[3,2‐b]thiophene‐3,6‐dicarboxylate ( TT‐Th ), is incorporated to construct a wide‐bandgap (1.88 eV) polymer PBDT‐TT for nonfullerene polymer solar cells (NF‐PSCs). PBDT‐TT possesses suitable energy levels and complementary absorption when blended with both ITIC analogues ( ITIC and IT‐M ) and a near‐infrared (NIR) acceptor ( 6TIC ). Moreover, PBDT‐TT exhibits good conjugated planarity and preferable face‐on orientation in the blended thin film, which are beneficial for charge transfer and carrier transport. The PSCs based on PBDT‐TT : IT‐M and PBDT‐TT : 6TIC blend films yield high power conversion efficiencies of 11.38% and 11.03%, respectively. To the best of the authors' knowledge, the PCE of 11.03% for PBDT‐TT : 6TIC‐ based device is one of the highest values reported for NIR NF‐PSCs. This work demonstrates that TT‐Th is a useful new electron‐accepting building block for making p‐type wide bandgap polymers for efficient NIR NF‐PSCs.     

Sodium Ion Stabilized Vanadium Oxide Nanowire Cathode for High‐Performance Zinc‐Ion Batteries

Aqueous Zn‐ion batteries (ZIBs) have received incremental attention because of their cost‐effectiveness and the materials abundance. They are a promising choice for large‐scale energy storage applications. However, developing suitable cathode materials for ZIBs remains a great challenge. In this work, pioneering work on the designing and construction of aqueous Zn//Na_0.33V₂O₅ batteries is reported. The Na_0.33V₂O₅ (NVO) electrode delivers a high capacity of 367.1 mA h g^?1 at 0.1 A g^?1, and exhibits long‐term cyclic stability with a capacity retention over 93% for 1000 cycles. The improvement of electrical conductivity, resulting from the intercalation of sodium ions between the [V₄O₁₂]_n layers, is demonstrated by single nanowire device. Furthermore, the reversible intercalation reaction mechanism is confirmed by X‐ray diffraction, Raman, X‐ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy analysis. The outstanding performance can be attributed to the stable layered structure and high conductivity of NVO. This work also indicates that layered structural materials show great potential as the cathode of ZIBs, and the indigenous ions can act as pillars to stabilize the layered structure, thereby ensuring an enhanced cycling stability.