According to the results of formation energy we calculated, upon substitution of Ni by Cu at levels of about 10.4 at.%, Ti50(Nix50−Cux) alloys lose the monoclinic martensite in favor of the orthorhombic martensite structure. The martensite monoclinic B19´ structure of Ni50(Tix50−Zrx) becomes more stable with increasing of the Zr content. The energy difference between austenite and martensite decreases when Cu < 10.4 at.%, and then increases slightly, which suggesting that Cu addition reduces the composition sensitivity of martensitic transformation temperature comparing with binary NiTi alloys. The energy difference decreases slightly firstly when Zr < 10.4 at.% and then increases sharply, which indicates that Zr addition increases martensitic transformation temperature dramatically. Furthermore, a geometric model is used to evaluate the thermal hysteresis. More interestingly, it is found that the lowest thermal hysteresis is achieved at 10.4 at.% for Cu-doped NiTi; whereas the thermal hysteresis increases with increasing of Zr. The electronic structures of austenite phase are also discussed in detail.Martensitic transformation and phase stability of Ti NiTi SMAs have been studied extensively and widely used for a variety of applications in a number of different fields, such as aeronautic, microelectronic and biomedical industries, since 1960s when first discovered by Buehler and Wiley2. However, some applications of the NiTi SMAs are greatly limited by its particular hysteresis (ΔT) and the martensite transformation temperature, Tm, is usually lower than 100 °C3. The need of addressing these limitations has led to numerous experimental and theoretical researches15.Among the reported shape memory alloys (SMAs), NiTi alloys are the most attractive ones due to their unique shape memory effect and excellent superelasticity, resulting from the reversible thermoelastic martensite transformation (MT) between the high-temperature austenite phase and low-temperature martensite phases4 depresses the Tm of NiTi alloys severely even at very small levels, but still results in a monoclinic martensite phase after MT. According to the recent reports6, there exists a strain glass (STG) transition in doped Ti50(Nix50−Dx)  alloys. Wang et al.7 discovered the existence of strain glass in Ti50Nix50−Fex, beyond a critical Fe doping level x > xc (5 < xc < 6). Alloying NiTi with Cu (Cu substitutes for Ni) reduces the thermal hysteresis8 and composition sensitivity of the transformation temperatures9, meanwhile, changes the MT pathway17.The addition of Fe and Co (substituted for Ni) or Al, V, Cr and Mn (substituted for Ti)10. These high-temperature shape memory alloys (HTSMAs) with the Tm higher than 100 °C have various potential applications. NiTiZr system has drawn much attention owing to the much lower cost compared with the noble metals . Experiments have indicated that, the Tm decreases with small amounts of Zr (X ≤ 3 at.%)18, and then sharply increases when Zr content exceeds 10 at.%, approaches as high as 170 °C for 20.2 at.% Zr13; martensite structure remains monoclinic (B19′)12; and its hysteresis is slightly wider than that of TiNi binary alloy13. Frenzel et al.19 found the strong dependence of Tm on alloy composition in binary NiTi, ternary Ni–Ti–X  and quaternary Ni–Ti–Cu–Y  SMAs.Transformation temperature increases linearly with the X content for alloys containing greater than approximately 10–15 at.% in ternary NiTi-X  SMAs20 conclude that the valence electron concentration is found to be an important parameter influencing the Tm. There requires a better understanding of how they affect the phase structure and properties and the strong composition dependence of Tm.From above experimental researches, it can be seen that the alloying elements play an important role in determining the phase transformation temperature, hysteresis as well as STG. Zarinejad and Liu21. The martensite crystal structures of Ti50Nix50−Cux SMAs were investigated by using CASTEP code22. Wang’s ab-initio calculations6 show the origin of STG transition in Ti50(Nix50−Dx)  alloys, and indicate that Cu and Pd cannot induce the STG transition. Hu et al.14 investigated the alloying effect of Zr on the elastic properties of Ni-rich Ni–Ti–Zr HTSMAs. Our previous work15 has investigated the effect of Pd on the martensitic transformation of Ni–Ti–Pd HTSMAs through DFT calculations. Attracted by the small hysteresis width8 and the low composition sensitivity of Tm9 in Ni–Ti–Cu alloys, the relatively low materials cost and large change of Tm in Ni–Ti–Zr HTSMAs13. Consequently, we devote this paper to study the phase stability and transition behaviors of Ni–Ti–Cu and Ni–Ti–Zr alloys based on DFT, further rationalize the experimental findings about MT, and explain the strong content dependence of the phase stability of martensite crystal structure, transformation temperature and thermal hysteresis.The first-principles has been used to study the microscopic origin of NiTi MT further. Recently, the site preference for ternary additions in NiTi has been systematic calculated23. As we are just concerned with the relative variations of the energy between austenite and martensite phases, the energy differences are almost unaffected by temperature. Transmission electron microscopy shows the presence of precipitates in Ni–Ti–Cu films after aging, precipitations vary with different annealings24. The effect of precipitation is beyond of the scope of the current work.Generally, the DFT calculations are implemented at the temperature of 0 K4, thus antisite defects were not discussed in the present work. In this paper, we adopt the Ti50(Nix50−Cux) and Ni50(Tix50−Zrx)  alloys as our modeling. Considering the symmetry of the cell, a 2 × 2 × 3 supercell containing 48 atoms of the austenite phase is chosen, and X, Y, Z directions are along [001]B2, B2, respectively. The lattice parameters are a0 is the lattice constants of cubic B2 phase. We focus on the orthorhombic B19 and monoclinic B19′ structures for the martensite phase observed experimentally in Ni–Ti–Cu and Ni–Ti–Zr shape memory alloys16. Figure 50(Nix50−Cux) and Ni50(Tix50−Zrx) alloys were shown in Supplementary Fig. We focus only on the Ti-deficient Ni–Ti–Zr and Ni-deficient Ni–Ti–Cu alloysWe calculate the most stable position of B2 phase with the principle of lowest energy first, and the site occupation of doped atoms of B19 and B19′ phase is set according to the B2. The energy difference between B2, B19 and B19′ phase is almost unaffected by the doping position. Moreover, the calculated deviations of energy of all possible doping position is about 0.2 eV.Ab initio Simulation Package27 (VASP) together with plane-wave projector augmented wave28 (PAW) pseudopotentials and the PW9129 generalized gradient approximation30 (GGA) for the exchange and correlation effects. The valence electron configurations for Ni, Ti, Cu and Zr are 3d84s2, 3d24s2, 3d104s1 and 4d25s1, respectively. We tested k-point sampling31 and an energy cutoff convergence for all supercells. As a result of the convergence tests, Brillouin zone sampling was performed using 4 × 4 × 4 special k-point mesh, the plane-wave cutoff energy was set to 500 eV. In the calculations, the total energies were converged up to 10−4 eV/atom, and the atomic positions in our models were fully relaxed until the force of every atom was less than 0.01 eV/Å. We relaxed the structure with ISIF = 7 option  first, and then, with ISIF = 2 option  in VASP.The calculations are performed using DFT as implemented in the Vienna Structural parameters adopted in the present work are summarized in Table Eform) for B2, B19 and B19′ phases of Ti50(Nix50−Cux) and Ni50(Tix50−Zrx) alloys, respectively. Eform is defined as the total energy of the alloy minus the concentration weighted average of the pure elements’ total energies at their equilibrium volumes34. As previously mentioned, the 2 × 2 × 3 supercell of B2, B19 and B19′ structures of Ti50(Nix50−Cux) and Ni50(Tix50−Zrx) alloys that contains 48 atoms are constructed. It is calculated (per atom) as50Nix50−Cux and Ni50Tix50−Zrx alloys respectively, Etot is the total energy of Ti50Nix50−Cux and Ni50Tix50−Zrx alloys, n is the number of doping atoms (Cu or Zr) in the supercell. The calculated results of Eform as a function of doping concentration are plotted in Fig. In order to analyze the effect of Cu or Zr additions on phase stability, we evaluate the formation energies , and, EfB19′ < EfB19 < EfB2 < 0, which reveals that the B19 and B19′ phases are more stable compared with the B2 phase, and, B19′ phase is the lowest temperature phase, which agrees with the experimental results16.Eform of each phase increases almost linearly with the increasing of Cu content which indicates that the phase stabilities of three structurers become worse  and Ni50(Tix50−Zrx) alloys have been calculated and plotted in Fig. Eform  of the austenitic phase with different doping concentration for Tisee Fig. .Figure 3It can be seen from Fig. E) between the austenitic B2 structure and martensitic B19 and B19′ structure, ΔE = EB2 − EB19/B19′. Table E = EB2 − EB19′ =  40.39 meV/atom) in NiTi alloys. The present calculations are in good accordance with other DFT studies.The transformation behaviors can be described by the energy differences  and Ni50(Tix50−Zrx) alloys. For Ti50(Nix50−Cux) alloys with low doping concentrations (Cu < 10.4 at.%), as 0 < ΔEB19 < ΔEB19′, as 0 < ΔEB19′ < ΔEB19, the most stable phase is B19, and ΔEB19 increases slightly with increasing Cu content, thus a little higher Tm occurs.The previous observationsee Fig. , the mossee Fig. , thus thEB19′ decreases slightly; with x further increasing, ΔEB19′ increases significantly. Lager ΔE indicates more energy is needed for the martensitic transformation thus corresponds to a higher Tm.It is clearly seen from Fig. E) as well as Tm as a function of the doping concentration of Ti50(Nix50−Cux) and Ni50(Tix50−Zrx) systems. Tm of Ni–Ti–Cu is cited from refs35, and Tm of Ni–Ti–Zr is cited from refs13. Addition of Cu decreases the Tm, and then increases slightly with further increasing of Cu content. This makes the Tm less sensitive to composition changes comparing with the binary NiTi alloys, which is in accordance with previous experimental works35. Zr addition raises the Tm obviously, which is fully in line with the experimental observations that the Zr additions increase the Tm dramatically13.In Fig. T) in shape memory alloys (SMAs) is the macroscopic presentation of the energy dissipation of the martensitic phase transformation, which plays an important role in their thermomechanical behavior. The geometric non-linear theory36 of martensite specifies several conditions for SMAs with extremely low hysteresis. The first condition U is the transformation stretch tensor that maps the martensite lattice to the austenite lattice, detU is its determinant and λ1 ≤ λ2 ≤ λ3 are the ordered eigenvalues of U. The second condition λ2 = 1 represents phase compatibility between austenite and martensite. The transformation stretch tensor between a bcc austenite and one particular lattice correspondence variant of an orthorhombic martensite is38Hysteresis (Δa0) and the orthorhombic martensite phase : Their values are entirely determined by the lattice parameters of the austenite  and λ2, but not with det(U), in Ni–Ti–Cu and Ni–Ti–Pd thin-films. Zhang et al.39 further demonstrated the same correlation for bulk alloys of Ni–Ti–Au, Ni–Ti–Cu, Ni–Ti–Pd, and Ni–Ti–Pt. Low hysteresis with phase compatibility between austenite and martensite was investigated in Ti50(Nix50−Pdx) system37. Recently, the direct correlation between thermal hysteresis and functional stability was demonstrated in binary (Ni-Ti), ternary  and quaternary (Ni-Ti-Cu-Pd) SMAs41.According to the above theory, Cui T) in the Ti50(Nix50−Cux) and Ni50(Tix50−Zrx) systems, we calculated λ2 values by λ2 shown as bB2, bB19 and bB19′ are the lattice parameters of the B2, B19 and B19′ structures in the [010] direction, respectively, and β is the monoclinic angle of the crystal structure of B19′ martensite. The calculated structural parameters of Ti50(Nix50−Cux) and Ni50(Tix50−Zrx) for different doping concentration are listed in Supplementary Tables λ2 vs. doping concentration for these alloys were shown in Fig. To investigate the influence of alloy elements content on thermal hysteresis , and the widths of the thermal hysteresis have a minimum for |1 − λ2| approaches 0 (Cu = 10.4 at.%). λ2 quantifies the geometric compatibility of the martensite and the austenite, and the fit between the two phases increases as λ2 approaches 141. The most stable martensite phase was changed from monoclinic to orthorhombic structure for Ti50(Nix50−Cux) alloys, which increases the phase compatibility, making λ2 approach 1. For other λ2 value which is lower or higher than 1, wider thermal hysteresis is observed. Adding Cu lower the width of the thermal hysteresis, ΔT appears to be minimized when Cu content at about 10.4 at.%at.%.As indicated in Fig. λ2 decrease slightly for Zr < 10.4 at.%, and then nearly stable, keeping further from 1  SMAs, which are in line with other literatures13.The value of see Fig. . This isEform, energy differences between austenite and martensite ΔE and the middle eigenvalue of transformation stretch tensor λ2 for Ti50(Nix50−Cux) and Ni50(Tix50−Zrx) systems allow us to draw the following conclusions. For Ti50(Nix50−Cux) alloys, when the doping Cu concentrations are less than 10.4 at.%, phase transformation takes place from B2 to monoclinic B19′ phase, while the doping concentration ≥10.4 at.%, phase transformation happens from B2 to orthorhombic B19 phase. According to the results of ΔE and λ2, for Cu < 10.4 at.%, adding Cu slightly decreases Tm and thermal hysteresis ΔT, moreover, gets a minimum of the widths of thermal hysteresis; with further doping, Tm and ΔT increase slightly. In short, the addition of Cu results in a decrease of Tm and ΔT. The present investigation exhibits that the replacement of Ti by Zr rises transformation temperature significantly, and increase the hysteresis slightly. Ni50(Tix50−Zrx) alloy remains the B19′ martensitic phase, which leads the phase compatibility between austenite and martensite reduced and larger lattice deformation involved.Our first-principles calculations on formation energies Supplementary materials


Mesobuthus martensii and then validated four genes from them via the combination of PCR and genomic sequence analysis. These four scorpion defensin genes share the same gene organization and structure of two exons and one phase-I intron with the GT-AG rule. Conserved motif and phylogenetic analysis showed that they belonged to the members of the invertebrate cysteine-stabilized α-helix/β-sheet motif defensin (CSαβ) defensin family. All these four CSαβ defensin genes have the expression feature of constitutive transcription (CON) by the whole scorpion infection model, promoter sequence analysis and dual luciferase assays. Further evolution and comparison analysis found that the invertebrate CSαβ defensin genes from most of arachnids and mollusks appear to share the expression pattern of CON, but those from insects and lower invertebrates  seem to have identical inducible transcription (IND) after being challenged by microorganisms. Together, we identified four scorpion CSαβ defensin genes with the expression feature of CON, and characterized the diversified expression patterns of the invertebrate CSαβ defensin genes, which will shed insights into the evolution of the invertebrate CSαβ defensin genes and their expression patterns.Defensins are important components of innate host defence system against bacteria, fungi, parasites and viruses. Here, we predicted six potential defensin genes from the genome of the scorpion  Defensins are small cationic antimicrobial peptides containing three or four intramolecular disulphide bonds formed by six or eight cysteine residues in a complex folded arrangement of two or three antiparallel β-sheets with or without an α-helix structure –4. DefenVertebrates’ defensins have six cysteine residues and are divided into three distinct families: α, β and θ defensins, which have lengths of 29–35, 35–45 and 18 amino acid residues respectively , nematodhttp://www.ntnu.no/ub/scorpion-files/specieslist.php). The scorpion M. martensii belonged to the family Buthidae and was used to be an important raw material in Chinese Traditional Medicine for the treatment of some nervous system diseases  (N could be any of the four bases and A+1 is the first base of the transcription start site) [+1ATTTT, TCA+1TTTCT and TCA+1GTTTT respectively  binding site, which is a critical member of inducible immune factors and has been found in promoter regions of almost inducible SCAMP genes in animals [Constitutive mRNA expression of the four scorpion defensins observed in the challenge experiment suggests a lack of immune response elements in the upstream regulatory regions of their promoters. Consequently, we attempted to clone and characterize their promoter regions based on the sequence of the scorpion rt site) ,36. BmKDectively . The iniectively . Althougectively a. BmKDfsectively b. The prectively c. All thosophila , mosquitosophila  and scorosophila ,36. Thus animals , suggestDrosophila which have closer relationship with scorpions than humans. Their promoter activities, as indicated by the ratio of firefly luciferase and Renilla luciferase activities, did not change upon stimulation with bacterial components  from the scorpion M. martensii at both the genome and cDNA levels. BmKDfsin4 was recently identified at the protein level by our research group [L. quinquestriatus and A. australis respectively, are both constitutively expressed independent of immune stimulus. Another scorpion defensin, Cll-dlp [We validated four defensin genes  cluster together and share the same expression type with each other, suggesting that the CSαβ defensin genes in these species are the product of a recent gene duplication event and that the expression type was established before this event. Most of the CSαβ defensins arising from gene duplication exhibit IND expression. In species other than insects, CSαβ defensins from the same species  do not cluster together, but most have the same expression type as arachnids, which implies that CSαβ defensin genes from these species underwent gene duplication before the split of scorpions, spiders and ticks and that the CON expression type of CSαβ defensins was formed after the gene duplication. This result was also consistent with the occurrence of CSαβ defensin CON expression type in mollusks. The use of the same CSαβ defensin expression mode within species and between closely genetically related species implies that the driving force behind the evolution of CSαβ defensin expression modes in invertebrates may be the similar immune challenges faced by these species. Most mollusk and arachnid species, such as snails and scorpions, usually live in an environment rich of a wide variety of microbial populations. Evolutionary CON expression type of CSαβ defensin genes in mollusks and arachnids possibly help them to defend microbial infection.Since CSαβ defensins from invertebrates have undergone unique routes of diversification and evolution along with the evolution of species from low to high, the driving force and potential biological role behind the evolution and diversification of the CSαβ defensin family are of interest. As shown in


However, the low utilization of the Li2S cathode and the lack of electrolytes compatible to both electrodes are impeding the development. Here, a novel graphite/Li2S battery system, which features a self‐assembled, holey‐Li2S nanoarchitecture and a stable solid electrolyte interface (SEI) on the graphite electrode, is reported. The holey structure on Li2S is beneficial in decomposing Li2S at the first charging process due to the enhanced Li ion extraction and transfer from the Li2S to the electrolyte. In addition, the concentrated dioxolane (DOL)‐rich electrolyte designed lowers the irreversible capacity loss for SEI formation. By using the combined strategies, the graphite/holey‐Li2S battery delivers an ultrahigh discharge capacity of 810 mAh g−1 at 0.1 C (based on the mass of Li2S) and of 714 mAh g−1 at 0.2 C. Moreover, it exhibits a reversible capacity of 300 mAh g−1 after a record lifecycle of 600 cycles at 1 C. These results suggest the great potential of the designed LFA/holey‐Li2S batteries for practical use.The pairing of high‐capacity Li Compared with sulfur‐based2Sx‐based (x > 2)2S cathodes have a unique merit of being paired with lithium‐free anode (LFA), e.g., graphite,2S‐based electrodes are advantageous in maintaining their structural integrity because the as‐prepared Li2S electrodes are at their maximal volume. As an LFA for Li2S‐based batteries, graphite can provide a higher cycling stability than conversion‐type Sn and Si anodes due to its smaller volume expansion (9–13%) upon lithiation. These incentives have motivated the development of graphite/Li2S batteries in recent years.2S oxidation during the first charge step and 2) the large irreversible capacity caused by the formation of SEI on the graphite surfaces.2S batteries.Because of its high theoretical specific capacity 1166 mAh g6 mAh g−12S powder shows a high potential barrier when activating Li2S cathode‐based batteries. The high potential barrier represents the difficulty in extracting lithium ion from Li2S,2S utilization. To address this issue, the size reduction of Li2S powders2S composites2S powder have been widely reported. However, the use of commercial Li2S powder does not reduce the cost of Li2S cathodes for consumer‐oriented batteries. The low‐cost production is highly important for energy storage systems and electric vehicle applications where battery cost reduction is a key driver for their successful implementation. As a cost‐effective route, the fabrication of Li2S cathodes by a carbothermal conversion of Li2SO4 has been reported recently,2S electrodes. However, due to the high conversion temperature required, most of the Li2SO4‐converted Li2S cathodes have a high potential barrier upon their activation. Therefore, to achieve a high Li2S utilization of Li2S cathodes with an intrinsically high potential barrier is a great challenge to advance the graphite/Li2S batteries.Because of its low electronic and ionic conductivity, bulk Li2S batteries. Previously, the electrolytes containing 1 m bistrifluoromethanesulfonimide lithium salt (LiTFSI) in dioxolane (DOL)/dimethoxymethane (DME) and LiNO3 additives were reported for graphite/Li2S batteries.2S cathodes with a high potential barrier. As a means to improve the oxidative stability of the ether‐based electrolyte, a highly concentrated electrolyte (5 m LiTFSI in DME) was suggested for lithiated graphite/sulfur batteries.On the other hand, electrolyte design is another critical issue for achieving high‐capacity graphite/Li2S nanoarchitecture fabricated by a facile, low‐cost, and solid‐state carbothermal reaction of Li2SO4, and a high‐performance graphite/Li2S battery with the holey‐Li2S‐based cathode as well as a conventional graphite electrode, and a concentrated DOL‐rich electrolyte. The unique holey nanostructure, which can expand the Li2S/electrolyte interface, facilitates the oxidation of Li2S during the initial activation process. A 3 m LiTFSI DOL‐rich electrolyte was rationally designed that considered the balance among ionic conductivity, oxidation stability, and SEI formation on the graphite anode. In addition, due to the use of the graphite anode instead of the Li metal anode, problematic polysulfide shuttle can be eliminated accordingly. The combined approach results in a graphite/holey‐Li2S battery that has an ultrahigh initial discharge capacity of 810 mAh g−1 at 0.1 C and the long lifecycle over 600 cycles at a 1 C rate. These performances are far superior to those of the previous studies on graphite/Li2S batteries  and even better than conventional lithium ion batteries in terms of specific energy . This suggests that the graphite/Li2S battery with holey‐Li2S nanoarchitectures and concentrated DOL‐rich electrolyte is highly promising for practical applications.Against the backdrop, we report a novel holey‐Li2S cathode consisting of micrometer‐sized Li2S particles with a hole (holey‐Li2S) and carbon nanotube (CNT) network is fabricated from a low‐cost commercial Li2SO4·H2O via a facile two‐step method . First, plate‐shaped Li2SO4 particles embedded in a CNT network (plate‐Li2SO4/CNT)  Figure1, leftFigure2SO4/CNT . The X‐ray diffraction (XRD) pattern for the as‐prepared Li2SO4/CNT electrode  indicates that the plate‐shaped architectures are a mixture of Li2SO4·H2O (Joint Committee on Powder Diffraction Standards (JCPDS) card No. 15–0873) and Li2SO4 (JCPDS card No. 20–0640). A magnified SEM image  images  acid (PAA) as a surfactant, which has a strong affinity with Li ion and thus favors the formation of Li2SO4 plates. The use of neutral poly(vinyl pyrrolidone) instead of PAA led to the formation of few micrometer‐long strip‐shaped Li2SO4 .2SO4 to Li2S during the carbothermal conversion is confirmed by the XRD pattern of the as‐converted Li2S electrode , which shows that the diffraction peaks perfectly match with those of the cubic Li2S phase (JCPDS card No. 26–1188). Interestingly, as shown in the SEM image of the as‐converted Li2S electrode  during the carbothermal reduction process. This is different in shape from the shapes of the previously reported Li2S particles derived from Li2SO4 compounds.2S nanoarchitecture has a wall thickness of 100–150 nm and a hole diameter of 200–500 nm. Evolution of the holey structure was further evidenced by the TEM image  are first consumed and the skin of the Li2SO4 plates is converted to Li2S, preventing the direct contact between the surrounding CNTs and inner Li2SO4. However, the reaction between the generated CO2 and CNT (CO2 +  2 C →  2 CO) produces CO,2SO can occur due to the strong reducing power of CO (Li2SO4 + 4 CO →  Li2S + 4 CO2). The carbothermal conversion accompanies the compaction of the plates, and due to the absence of the nearby CNTs, the resulting Li2S plates become closer and eventually merge into a holey structure (right). The absence of CNT inside the hole suggests that the removal of CNT drives the assembly of the Li2S plates. The jointing of two plates observed for the holey‐Li2S particle  further supports the self‐assembled process of Li2S plates.The inscrutable structural change from plate to doughnut can be understood as a self‐assembly of the plates with the consumption of the near‐by CNT matrix Figure i. As ind2S particulate without any holes was prepared by further heating the above holey‐Li2S nanoarchitectures at 1000 °C for 3 h. Since the applied temperature is higher than the melting point of Li2S (938 °C), the holey structure was disrupted and a nonholey Li2S particulate was obtained, as shown in the SEM image and XRD pattern of the nonholey Li2S (solid‐Li2S) .For comparison, a Li2S batteries, the selection of liquid electrolytes presents a challenge. In this work, we paid attention to 3 m LiTFSI DOL/DME electrolytes by considering the balance between high oxidation stability, high ionic conductivity, and the compatibility with Li2S cathode and graphite anode. As shown in Figurem LiTFSI DOL/DME electrolytes with different DOL/DME volume ratios  showed higher oxidation stabilities compared with 1 m LiTFSI in DOL/DME = 50/50 with 0.2 m LiNO3, which is conventionally used for Li2S or sulfur batteries. Although the oxidative stability might be further improved by increasing the LiTFSI concentration, there is a significant loss in ionic conductivity as previously reported.m could not be achieved .To achieve high performance graphite/Lim TFSI DOL/DME electrolytes with graphite anode, the CEs during the 0.1 C rate cycling were measured for the graphite/Li batteries with the 3 m LiTFSI DOL/DME electrolytes. As shown in Figure m (16.3%) and 2 m (65.4%) LiTFSI in DOL/DME = 85/15, respectively , suggesting a relatively smaller irreversible lithium consumption for SEI formation on graphite for the three electrolytes. For the DOL‐rich electrolytes , the CEs reached over 99% after a few cycles, indicating the formed SEI films are quite stable. For the DOL/DME = 50/50 electrolytes, CEs gradually increased with the cycle, suggesting a gradual coverage of the SEI film on the graphite anode with the cycle. The DOL/DME = 0/100 electrolyte exhibited a fast CE fade with the cycle, which indicates that the SEI layer formed by 3 m TFSI in DME is not dense enough to prevent the cointercalation of the lithium ion and DME molecular into graphite.−1 were obtained over 40 cycles, which could be ascribed to a compact and uniform SEI layer derived from the DOL solvent−1), which can be attributed to the large irreversible capacity at the first charging step. Therefore, the DOL‐rich electrolytes  are more suitable for the graphite anode.In order to check the compatibility of the 3 2S cathode for the three DOL‐rich electrolytes were assessed with Li/holey‐Li2S batteries. As shown in Figure S10 in the Supporting Information, the first discharge capacity was 773, 880, 792, and 870 mAh g−1 for DOL/DME = 100/0, 85/15, and 75/25 and 50/50, respectively. The discharge voltage plateau was 2.05, 2.10, 2.10, and 2.10 V for DOL/DME = 100/0, 85/15, 75/25, and 50/50 respectively. However, the initial potential barrier of Li2S cathode increases with the increase of DME content in the electrolyte and, when the content of DME arrives at 100%, the initial charge/discharge process quickly completed with a very low charge/discharge capacity . These results indicate that a certain amount of DME is needed to attain the compatibility with the Li2S cathode, as previously observed for Li/sulfur batteries.m electrolytes and the lower concentrated electrolytes. Therefore, taking the above results into consideration, the 3 m LiTFSI DOL/DME = 85/15 electrolyte was selected for the graphite/holey‐Li2S battery.The compatibilities with LiFigure2S and graphite/solid‐Li2S batteries. The holey‐Li2S cathode showed a lower initial potential barrier than the solid‐Li2S electrode, which means that the holey structure facilitates the lithium extraction from Li2S. The charging capacity for the first charging with a cut‐off voltage of 3.8 V was 1166 mAh g−1 for the graphite/holey‐Li2S and 750 mAh g−1 for the graphite/solid‐Li2S. It clearly shows that, by introducing the submicrometer scale hole to the Li2S particle, the charging overpotential for the Li2S oxidation can be considerably lowered and a higher depth of charging can be obtained.2S battery and graphite/solid‐Li2S battery at 0.2 C after the initial activation were investigated . The graphite/holey‐Li2S battery showed a lower capacity fade rate (0.184%/cycle) than the Li metal/holey‐Li2S battery (0.414%/cycle) , demonstrating the benefit of using graphite instead of Li metal in terms of cycling stability. The CEs of the graphite/holey‐Li2S battery were maintained above 99% during the whole cycles, which is contrasted by the CEs around 98% for the Li /holey‐Li2S battery . It indicates that the polysulfide shuttle can be suppressed in the graphite/holely‐Li2S battery. To further clarify the polysulfide shuttle issue, the lithium metal and graphite electrode of the Li2S batteries were analyzed by X‐ray photoelectron spectroscopy (XPS) after the initial charge. As shown , the peaks from the insoluble Li2S/Li2S2 were clearly detected for the lithium metal surface electrode, while these peaks were unseen for the graphite surface, ensuring the prevention of polysulfide shuttle in the graphite/Li2S battery. The discharge capacity of the graphite/solid‐Li2S battery gradually increased from 237 to 450 mAh g−1 during the first 30 cycles, followed by a mild capacity fade. The initial capacity increase in the early cycles suggests that the unactivated Li2S particles gradually decomposed during the cycle. In spite of the additional Li2S activation, the maximum discharge capacity was still far lower than that of the holey‐Li2S electrode.The cycling performances of the graphite/holey‐Lid Figure b. The gr2S electrode was evaluated by investigating the discharge capacities for five cycles at a discharge rate with a successively increasing discharge rate as 0.1, 0.2, 0.3, 0.4 0.5, 0.6, 0.8, and 1 C and returning to 0.1 C. As shown in Figure −1 for the discharge rate of 0.1, 0.2, 0.3, 0.4 0.5, 0.6, 0.8, and 1 C, respectively. When the discharge current density returned to 0.1 C, a high discharge capacity of 664 mAh g−1 was recovered. The capacity retention from the C rate increase from 0.1 to 1 C was 75%. In addition, the graphite/holey‐Li2S battery showed a high discharge potential plateau of 1.99 V at 0.1 C and 1.68 V at 1 C , which will be described in a later section. For sulfur cathodes, the efficacy of the multiscale porosity with micrometer and submicrometer pores in enhancing the rate capability was previously demonstrated.The rate capability of the holey‐Li2S battery can be further supported by a comparison of battery energy densities between the graphite/LiCoO2 and graphite/holey‐Li2S batteries  is 270 Wh kg−1 for the graphite/holey‐Li2S battery and 206 Wh kg−1 for the graphite/LiCoO2 battery, respectively. The comparison indicates that the holey‐Li2S cathodes can exceed conventional metal oxide cathode in terms of energy density.The superiority of the graphite/holey‐Li2S battery. When the current density was increased to 1 C after the initial activation at 0.1 C for the cycling, the discharge capacity at the first cycle was as low as 195 mAh g−1. This is because the redistribution of the sulfur species over the CNT network was not fully proceeded during the initial activation. However, the discharge capacity gradually increased up to a maximum value of 400 mAh g−1 after 70 cycles, which was probably due to a gradual redistribution. To our interest, the discharge capacity of 300 mAh g−1 was maintained at 600 cycles with a high CE of 99%, which firmly demonstrates the merit of the graphite/holey‐Li2S battery in terms of discharge capacity and cycling stability.Figure 2S cathode:Li2S → S + 2Li+ + 2e−, the original Li2S is converted into lithium polysulfides and sulfur upon the initial activation process. Accordingly, the electric energy is stored in the battery system, which can be used in the discharge process. Therefore, the initial activation process is highly critical to the electrochemical performances of Li2S batteries. To further understand the structural and electrochemical changes during the initial activation for the holey‐Li2S and solid‐Li2S cathodes, SEM, XRD, and electrochemical impedance spectroscopy (EIS) analysis were conducted for the two electrodes, and the results are compared in Figure2S particles completely disappeared  indicate that the high performances of the graphite/holey‐Li2S battery can be attributed to the three cooperative contributions; 1) The holey‐Li2S nanostructure which facilitates the decomposition of Li2S particles during the initial activation, 2) the formation of a stable SEI layer on graphite with the electrolyte, and 3) the prevention of the polysulfide shuttle due to the use of the graphite anode. We believe that the novel holey‐Li2S nanoarchitectures and the electrolyte design can boost the development of high‐energy LFA/Li2S batteries for practical applications.In summary, a novel holey‐LiFabrication of Electrode Materials: In this work, the commercial lithium sulfate monohydrate , PAA (Sigma‐Aldrich), ethanol (EMD millipore corporation), and poly(vinyl pyrrolidone)  were used without further purification.2S/CNT electrodes were fabricated by the following two steps. First, the sandwich‐typed plate‐Li2SO4/CNT electrodes were prepared by a precipitation method. Detailedly, an 80 mg of Li2SO4·H2O powder was dissolved into a 5 mL of deionized water upon stirring to form a transparent Li2SO4 solution. At the same time, a 25 mg of CNT and a 100 mg of PAA were in turn added to a 50 mL of absolute ethanol to form a uniformly dispersed CNT suspension via a sonication of 30 min. Then, another CNT suspension was prepared by the same treatment . After that, the suspension containing a 25 mg of CNT mixed with a more 50 mL of ethanol  and the prepared Li2SO4 aqueous solution were soaked in an iced water bath for 30 min upon stirring. Followed this step, the icy Li2SO4 solution was transferred to a syringe and was injected slowly to the icy CNT suspension upon stirring to obtain a uniform Li2SO4/CNT suspension. Finally, the Li2SO4/CNT suspension was used to fabricate a sandwich‐typed Li2SO4/CNT film by a vacuum filtration . The as‐fabricated sandwich‐typed film was peeled off and dried, and was punched into disks with a diameter of 12 mm for further drying at room temperature for overnight. Second, the holey‐Li2S/CNT electrodes were obtained by a carbothermal reaction. Operationally, the as‐prepared Li2SO4/CNT electrodes were put into the tube furnace under a flowing N2 at 700 °C for 3 h and were converted into final holey‐Li2S/CNT electrodes. The solid‐Li2S/CNT electrodes were obtained via a further heat treatment of holey‐Li2S/CNT at 1000 °C for 3 h. The Li2S content and Li2S area loading in the two electrodes according to the mass change of before and after dissolution of Li2S into ethanol and deionized water are around 48 wt% and 2.0–2.25 mg cm−2, respectively.In a typical experiment, the freestanding holey‐LiMicrostructure Characterization: The crystalline phase structures of all the converted electrodes were characterized by XRD (Smart lab). The morphology and structure of the electrodes were characterized by SEM (S4800) and TEM (Tecnai F30 ST). XPS characterization was carried out on an X‐ray photoelectron spectroscopy (Kα). EIS data were collected in a frequency range of 1 MHz to 10 Hz using an alternating current (AC) impedance analyzer with amplitude of 10 mV. The electrochemical measurements were carried out on a battery cycler (TOSCAT‐3000U) at 25 °C.Electrochemical Characterization: Electrochemical performances of the electrodes were evaluated by using the assembled button‐type batteries. The holey‐Li2S/CNT and solid‐Li2S/CNT electrodes were used as a working electrode and lithium metal foil  or graphite electrode (full batteries) (provided by Samsumg Company) were used as a counter electrode. Celgard 2400 and 3 m‐LiTFSI in DOL/DME (=85/15) were used as a separator and an electrolyte, respectively. All the batteries were assembled in an argon‐filled glove box (H2O and O2 content: <1 ppm). For charge/discharge behavior at a constant current density, the Li/Li2S batteries were first charge to 4.0 V then discharged to 1.5 V at a rate of 0.1 C (1 C = 1166 mA g−1). After that, the battery was cycled at a potential range from 1.5 to 3.0 V at a rate of 0.2 C. For the graphite/Li2S full batteries (the capacity ratio of graphite anode and Li2S cathode is around 1.05–1.1:1), the batteries were first charged to 3.8 V and then discharged to 1.0 V at a rate of 0.1 C. Subsequently, the batteries were cycled at a rate of 0.2 C/1 C with a potential range from 1.0 to 3.0 V. The rate capabilities of the graphite/holey‐Li2S battery were evaluated in a successive manner by varying the charge/discharge current density as 0.1, 0.2, 0.3, 0.4 0.5, 0.6, 0.8, and 1 C, and finally went back to 0.1 C, respectively.The authors declare no conflict of interest.SupplementaryClick here for additional data file.


By using real analysis and weight functions, we obtain a few equivalent statements of a Hilbert-type integral inequality in the whole plane related to the kernel of exponent function with intermediate variables. The constant factor related to the gamma function is proved to be the best possible. We also consider some particular cases and the operator expressions. In 1925, by introducing the pair of conjugate exponents If mentclass2pt{minimmentclass2pt{minimmentclass2pt{minimmentclass2pt{minimIn 2007, Yang  providede et al. –19 proveIn 2017, Hong –25).In this paper, by using real analysis and weight functions we obtain a few equivalent statements of a Hilbert-type integral inequality in the whole plane related to the exponent function with intermediate variables. The constant factor related to the gamma function is proved to be the best possible. We also consider some particular cases and operator expressions.For ion (see ).For Forwe haveand forwe haveSetting ent}c>0,  follows, we have , and forThe lemma is proved. □In the following, We further assume that given by , and6\dFor For fixed For For fixed In view of  and 10)10), we hWe have the following inequalities:If there exists a constantMsuch that, for any nonnegative measurable functionsandinthen we haveIf , and by  and 5)  \documen1q<∞. By  and 13)\documentIf , and by  and 5)  \documenmentclasspt{minima1q<∞. By  ). By  it follo(1)n. By  (for \domma (see ), 16), , \documeThe lemma is proved. □We define the following weight functions:Then we haveFor fixed  we have .The lemma is proved. □IfMis a constant, then the following statements (i), (ii), and (iii) are equivalent: (i)For anywe have:(ii)For anywe have:(iii)and(i)=>(ii). By Hölder’s inequality (see ) we have Then by  we have  Then by .(ii)=>(iii). By Lemma entclass1pt{minima(iii)=>(i). For ght (see ) and (18By Fubini’s theorem (see ), 24), , 24), an we have  , (ii), and (iii) are equivalent.The theorem is proved. □IfMis a constant, then the following statements (i), (ii), and (iii) are equivalent: (i)For anysatisfyingwe have:(ii)For anysatisfyingandsatisfyingwe have:(iii)Moreover, if statement (iii) holds, then the constant factorin (and (is the best possible.γ)(σ)in  and 26)Moreover,In particular, (1) forwe have the following equivalent inequalities with nonhomogeneous kernel:whereis the best possible constant factor;forwe have the following equivalent inequalities with homogeneous kernel of degree 0:whereis the best possible constant factor.(2) A and B such that they are not both zero and (see [For  (i), if  takes thand (see )\docume∞. Hence  takes th∞. Hence . Hence (∞. Hence  and 26)\documentIn view of Theorem When statement (iii) holds, namely, uch that  is validγ)(σ) in  is the bThe constant factor γ)(σ) in  is stillγ)(σ) in  (for \doγ)(σ) in  is not tThe theorem is proved. □We set the following functions: entclass1pt{minimay∈R), by  we haveDefine the Hilbert-type integral operator T is bounded and satisfiesIn view of , it follTf and g asIf we define the formal inner product of entclass1pt{minimaIfMis a constant, then the following statements (i), (ii), and (iii) are equivalent: (i)For anywe have:(ii)Forwe have:(iii)Moreover, if statement (iii) holds, then the constant factorin (σ)in  and 33)Moreover,(1) In particular, for α=β=0 in  and 28)\documentIf (2) For α=β=0 in  and 30)\documentIf In this paper, by using real analysis and weight functions we obtain a few equivalent statements of a Hilbert-type integral inequality in the whole plane related to the kernel of exponent function with the intermediate variables Theorem . The con


This study investigated the spatiotemporal variability of bubble and diffusive CH4 emissions from a subtropical reservoir, including its upstream and downstream rivers, in eastern China. There was no obvious seasonal variation in CH4 emissions from the main reservoir, which increased slightly from the first half year to the next half year. In the upstream river, CH4 emissions were low from February to June and fluctuated widely from July to January due to bubble activity. In the downstream river, CH4 emissions were lowest in February, which was possibly influenced by the low streamflow rate from the reservoir (275 m3 s−1) and a short period of mixing. There was spatial variability in CH4 emissions, where fluxes were highest from the upstream river (3.65 ± 3.24 mg CH4 m−2 h−1) and lowest from the main reservoir (0.082 ± 0.061 mg CH4 m−2 h−1), and emissions from the downstream river were 0.49 ± 0.20 mg CH4 m−2 h−1. Inflow rivers are hot spots in bubble CH4 emissions that should be examined using field-sampling strategies. This study will improve the accuracy of current and future estimations of CH4 emissions from hydroelectric systems and will help guide mitigation strategies for greenhouse gas emissions.Subtropical reservoirs are an important source of atmospheric methane (CH Greenhouse gas emission data are available for 36 Asian reservoirs, of which CH4 emission flux data have been reported for three reservoirs in China, including Three Gorges3, Ertan4, and Miyun5. However, there are more than 98,000 dams of varying sizes and 142 large-size hydroelectric reservoirs in a range of geographical regions and climate zones in China, excluding dams that are either under construction or planned, from which CH4 emission fluxes remain to be assessed.Hydropower has historically been regarded as a clean energy source, however, the view is challenged by a growing body of research that considers hydroelectric reservoirs to be carbon sources. For example, Deemer 4 emissions from open water areas of reservoirs6. Ebullition has been shown to be the dominant CH4 emission pathway, albeit episodic7, but pulses of gas bubbles often occur during periods of rapidly falling barometric pressure in lakes, reservoirs, and peatland10. Ebullitive CH4 flux is reported to be 1–3 orders of magnitude greater than diffusive CH4 flux12, and high ebullitive CH4 flux, observed in shallow water, river deltas, and inflow rivers13, is shown to be influenced by allochthonous organic carbon input and burial14. Chamber methods were used to measure CH4 emission flux from three large reservoirs in China, where the total CH4 emission flux (diffusion + ebullition) was measured across the water-air interface5; however, it is likely that these studies did not capture the magnitude of bubble CH4 flux.Diffusive flux and gas bubble flux are the primary pathways for CH4 sources with strong spatial variability15. Such variations are presumably caused by changes in hydrological characteristics from impoundment. For example, increases in the water level, reduced water velocity, and flooded soils near the bank impact CH4 emissions from a new reservoir compared with the original river16. Similarly, CH4 emission levels from outlets downstream and inflow rivers upstream of reservoirs were distinct from those of the reservoir water18, due to variability in hydrological variables, such as water velocity and depth2, and dam operation strategy19. Temporal variability in CH4 emissions has been attributed to changes in temperature, water column mixing, dissolved oxygen (DO) concentration, and other environmental variables, including retention time and benthic metabolism21. For example, CH4 emissions were greater in summer than in other seasons at the Three Gorges Reservoir and were regulated by temperature, DO, and water velocity2, whereas they were only regulated by temperature at three lakes  in southwest Sweden20. Analysis of these differences in effects of environmental factors on spatiotemporal variability in CH4 emissions from reservoirs may result in more accurate estimates of the total CH4 emissions than previously determined.Subtropical reservoirs are strong atmospheric CH4 emits in the downstream river when the hypolimnion water passes through turbines and spillways because of the differences in temperature and pressure. The rapid stream of water increases the water current velocity, which enhances the gas transfer velocity at the air-water interface and improves downstream CH4 emission flux22. 50% of the total CH4 emissions recorded downstream from the Balbina Reservoir in Brazil18 represented approximately 30% of the total greenhouse gas emissions from the eight reservoirs in the dry tropical biome region of the country23, whereas downstream emissions accounted for 10% of the total CH4 emissions from the Nam Theun 2 Reservoir in Laos24.Emissions occur from rivers downstream of reservoirs, due to degassing fluxes at turbines and spillways. A large quantity of CH4 emissions from a reservoir with sites upstream and downstream to quantify spatial variations in CH4 emissions to ensure a more accurate estimation of CH4 emissions from hydroelectric reservoir systems. Specifically, we tested the hypothesis that upstream and downstream CH4 emissions are greater than from a reservoir.In this study, we compared CH4 emission flux, and bubble CH4 concentration, all of which were lower in spring than in summer and autumn , mean bubble CH4 flux rate was 22.62 ± 15.1 mg CH4 m−2 h−1 (range: 0.31–52.27 mg CH4 m−2 h−1), and mean CH4 concentration by volume in the collected gas was 59.04 ± 23.3% (range: 7.32–86.03%). Ebullitive CH4 flux positively correlated with the ebullition rate  and bubble CH4 concentration  were low from February to June, but increased and fluctuated from July to January  lake on 1 August (DOY: 213) and 8 February , SW, and southeast (SE) lakes in the next half year were 1.72, 1.54, 1.57 times as many as those in the first half of year, respectively. In addition, there was some temporal variation in mean CH4 emissions downstream of the reservoir (DR), where it was highest in December 2014 and lowest in February 2015; otherwise, emissions were generally constant  was 2.73 ± 2.02 mg CH4 m−2 h−1 and diffusive CH4 flux (NW-D) was 0.92 ± 1.22 mg CH4 m−2 h−1 , which was lower than in the downstream river, where it was 0.49 ± 0.20 mg m−2 h−1  were significantly higher than those from the second nearest sampling-point  are lower than those from the other temperate and subtropical reservoirs listed in Table 26. The mean CH4 emissions from the upstream river in the study are comparable to that from Three Gorges Reservoir (2.72 mg CH4 m−2 h−1), which is one order of magnitude greater than that from Eguzon Reservoir (0.24 mg CH4 m−2 h−1), but significantly lower than those from Australian reservoirs and an agriculturally impacted reservoir in the United States, due to the differences in bubble activity (Table 4 fluxes observed among the reservoirs12. Frequency of bubble occurrence upstream of the reservoir is low (16.2%), and the average ebullitive CH4 emission level is 16.83 mg CH4 m−2 h−1 (Table 4 m−2 h−1), Gold Creek (172.4 mg CH4 m−2 h−1), and Little Nerang Dam  measured using bubble traps was approximately 5 times higher than that measured using floating chambers (3.65 ± 3.24 mg CH4 m−2 h−1). These differences can be explained by the sudden release of bubbles on these rare occasions, which reveals strong spatiotemporal heterogeneities of the ebullition process because ebullition is highly sporadic and occurs during a very short period of time7. The measurements using floating chambers are conducted over a short period of time and a small surface might lead to an underestimation of this emission pathway if hot spots and hot moments are missed during the deployment of the chambers. Such a phenomenon is strongly smoothed when using bubble traps over longer periods of time than the typical floating chamber deployment time (20–33 h versus 20–30 min)30.In the upstream river, CHing Fig. . One of 4 emissions from the upstream river is that they were measured in different years (2014–2015 versus 2016–2017). Admittedly, interannual variability in upstream CH4 emissions presumably caused unnecessary errors. However, if the average CH4 flux is calculated only from these bubble-captured chambers in the NW transect in 2014 and 2015, it is 16.83 ± 12.48 mg CH4 m−2 h−1, which is approximately 25% less than that measured by the bubble traps (22.62 ± 15.1 mg CH4 m−2 h−1) in 2016 and 2017. Although both the interannual variability and different methods contributed to variances, differences remained in CH4 emissions when the diffusive and ebullitive CH4 fluxes were synchronously measured due to episodic bubbles. Nevertheless, the partitioning of bubble and diffusive CH4 emissions is an uncertainty in this study.Another explanation for the differences in CH4 emissions from the reservoir in the second half of the year were higher than in the first half of the year  found that oxycline and thermocline progressively sank in Xin’anjiang Reservoir in the second half of the year25. Vertical transport of CH4 in the water column is typically limited by slow rates of diffusion through the thermocline or oxycline31, and thermal and DO stratification typically become weaker in the second half of year, presumably resulting in increases in CH4 flux at the air-water interface.We observed that mean CHear Fig. ; this wa25. However, the vertical distributions of CH4 and O2 concentrations, and temperature were not measured in this study, which failed to illuminate the temporal variability in CH4 emissions. Lake overturn is a hot moment that exhibits disproportionately high CH4 emissions and CH4 oxidation32. Many studies indicate that CH4 storage sharply decreases during seasonal overturn periods35, emitting 12–46% of the total CH4 to the atmosphere, whereas the remainder (54–88%) is consumed by methane-oxidizing bacteria35. Although a minor proportion of the storage CH4 was emitted to the atmosphere, the contribution to the annual diffusive CH4 emissions was still great35, and even extremely diffusive CH4 fluxes occurred33. However, CH4 emissions from the main reservoir did not show a pulse in February and May  on 1 August (DOY: 213) in the SW lake  in July  on 8 February (DOY: 39) in the SW lake , respectively, when the wind speed reached 8–10 m s−1, whereas the lowest CH4 flux at SWD5 (0.049 mg CH4 m−2 h−1) occurred in the central area of the reservoir due to the low wind speed (2.63 m s−1). Many studies support the opinion that CH4 emissions from water surfaces can be enhanced by strong wind speeds37.We recorded another peak, albeit low (0.16 ± 0.097 mg CH4 emissions (including degassing at the turbines) have been found to be proportional to streamflow19. It is impossible to calculate the degassing emissions from the turbines at Xing’anjiang Dam based on the differences in CH4 concentrations between the water intake and water outlet below the dam because access is forbidden 500 m upstream and downstream of the dam due to safety concerns. However, measurements of CH4 emissions at four distances downstream of the dam, taken 13 times in 2015  in February, which is presumably a result of a low discharge flow rate (275 m3 s−1). Another possible explanation for the low flux is related to the lake overturn phenomenon in February25. Most of the CH4 stored in the hypolimnion is oxidized or released to the atmosphere during overturn periods35, and a very small fraction of the original quantity of CH4 remains in the water column32; thus, a low CH4 flux level was measured in the downstream river in February  rather than in the shallow zone (<5 m), and we suggest that the high ebullitive CH4 emissions from deep water zones are related to heterogeneous sediment accumulation13 because little or no sediment accumulates along reservoir margins39.Upstream CHlux Fig.  are drivlux Fig. . In cont4 emission rate at the upstream site (NW) was one to 2 orders of magnitude greater than the other sites 43 and the discharged water derived from the hypolimnion layer almost year round . The water adjacent to the dam is thermally stratified, where water in the warmer, upper layer (epilimnion <33 m) is in contact with the atmosphere and is more oxygen-rich, whereas the deeper, colder layer (hypolimnion) contains relatively low levels of O2 concentration25. We suggest that CH4 produced in the reservoir is easily stored in the hypolimnion45, and the release of dissolved CH4 to the atmosphere occurs due to differences in pressure, temperature, and turbulence when water passes through the turbines and spillways19. Water passing through the turbines and spillways is drawn from the hypolimnion, and downstream CH4 emissions are released under decreased pressure below the dam19.We recorded higher CHdam Fig.  that had4 emissions from the main reservoir is that the deep, oxic waterbody slows emissions by offering more options for CH4 oxidation. Water depths of the sampling points range from 10–69 m, except for those on the margin  reported that the DO concentration never fell below 2 mg/L, the critical value for anoxia, in Xin’anjiang Reservoir25. The lack of an anoxic layer permits the oxidization of dissolved CH4 under aerobic conditions by methanotrophic bacteria27. Furthermore, biomass clearing before flooding limited the availability of organic carbon43, which is important for CH4 production in sediments41. Chlorophyll a is a significant predictor of CH4 emissions from reservoir water surfaces37, and Xin’anjiang Reservoir is presently in an oligotrophic state, with a low concentration of chlorophyll a (1–3 μg L−1)26, which limits CH4 emissions from the reservoir. Moreover, the dendritic shape of Xin’anjiang Reservoir facilitates the deposition of allochthonous organic carbon in the sediment of the NW lake  of the total CH4 emissions in some Amazon tropical reservoirs18. However, if turbine intakes are located in the upper layer of a dam, shallow waters will be withdrawn during thermal stratification to avoid substantial CH4 degassing from the CH4-rich water in the hypolimnion19, for example, only 0.8% from Harsha Lake27. Moreover, a significant increase in CH4 emissions was reported 3 km upstream from Nam Theum 2 Dam due to the artificial mixing induced by water intakes33, and CH4-rich water from the reservoir’s hypolimnion reached the surface and resulted in a high CH4 diffusive flux. Therefore, the water intake in the hypolimnion not only increased the degassing flux at the dam but also risked enhancing the CH4 diffusive flux upstream of the dam.Dam design is also important for CH4 emissions, significantly contributing to the total CH4 emissions from hydroelectric reservoir systems. If upstream sites are ignored in field-sampling strategies, entire-system CH4 emissions will be underestimated. CH4 emissions from a main reservoir are lower than that from a downstream river. Capturing the spatial heterogeneity of CH4 emissions is vital to estimating the total CH4 emissions in a hydroelectric system. Seasonal variation in CH4 emissions exhibited a high value in autumn and winter and a low value in spring and summer. A thorough investigation should be conducted for the entire reservoir region over a long period because bubbles are episodic and diffusive CH4 emission flux exhibits a strong spatiotemporal variability.In summary, upstream rivers are hot spots in bubble CH2 and mean depth of 37 m, with a capacity of approximately 1.78 × 1010 m3 43, and an annual average inflow and outflow of 9.4 × 109 m3 and 9.1 × 109 m3, respectively. Water retention time is approximately 2 years, and in 2015, the water level fluctuated between 98 and 104 m above elevation  is located in China’s north subtropical zone. The mean annual air temperature, precipitation, and evaporation are 17.7 °C, 2015.1 mm, and 712.9 mm, respectively .4 emissions was collected using floating static chambers and analysed by gas chromatograph. Three floating static chambers  at each sampling point comprised a non-covered plastic box wrapped in light-reflecting and heatproof materials to minimize internal temperature variation, with plastic foam collars fixed to opposite sides. The headspace height inside the chamber was approximately 35 cm. A silicone tube  was inserted into the upper central side of the chamber to collect gas samples that were then dried to prevent biological reactions in plexiglass tubes filled with calcium chloride . Another silicone tube was inserted into the upper corner of the chamber to maintain a balance in air pressure between the inside and outside of the chamber. Static chambers drifted freely behind a boat to reduce measurement bias49. Samples of gas were collected from the static chamber in air-sampling bags  four times every 7 min over a 21-min period using a hand-driven pump  and were stored until analysis2. The air-sampling bags made of aluminium are suitable for gas storage for 7 days and do not absorb or react with CH4. Leakage and memory effects of the air-sampling bags were tested in earlier experiments.Flux of diffusive CH8. Each funnel was stabilized with three equally sized weights to ensure no tiny bubbles remained in the traps at the initial stage. Trapped gas bubbles liberated from water were collected in the bottles after 24 hours, and then the remaining volume of water was measured to calculate the volume of liberated gas bubbles. The trapped gas was diluted 1000 times by injecting 1 × 10−3-L of trapped gas into 1- or 0.5-L gas bags that had been filled with N2 to facilitate analysis of CH4 concentration by gas chromatography. Trapped gas within these bags was analysed within 3 days using a gas chromatograph  equipped with a flame ionization detector (FID). The oven, injector, and detector temperatures were set at 70, 25, and 200 °C, respectively. Standard mixed gas  was used to quantify the CH4 concentration in one of every 10 samples, and the coefficient of variation of CH4 concentration in the replicated samples was <1%.We placed 16–26 bubble traps 10–15 m apart in a river crossing rope in the upstream river, where water depth ranged from 5–25 m. The traps consisted of an inverted 30-cm diameter circular funnel fixed to the neck of a 0.56-L plastic bottle, and an additional skirt (50-cm diameter) was fixed to the funnel aperture to enlarge the area over which bubbles were collecteddc/dt) within the static chamber was calculated as the slope of the linear regression of the gas concentration versus time. Diffusion chambers collect diffusive emissions as well as ebullitive emissions if they are present. Therefore, if the slope of the linear regression of the gas concentration in the chamber versus time was linear, with R2 > 0.9, then the chamber was assumed to collect only diffusive emissions. If R2 < 0.9, then the chamber was assumed to collect total (diffusive + ebullitive) emissions30.The increasing rate of gas concentration  is calculated as (Eq. ρ is the density of gas under the standard conditions (0.714 kg m−3 for CH4), H is the height from the top of the inverted chamber to the water surface , 273.15 is the absolute temperature at 0 °C, and T is the air temperate (°C).The flux of diffusive CH4 via ebullition (F2: mg CH4 m−2 h−1), measured as the bubble CH4 flux by bubble traps, is calculated as (Eq. CCH4 is the CH4 concentration (μL L−1), V is the accumulated headspace gas volume (L), M is the molar weight of CH4 (16.04 g mol−1), Af is the funnel area (0.14 m2), t is the measurement duration (h), and Vm is the molar volume of gas at room temperature (22.4 L mol−1)8.The flux of CHER; mL m−2 h−1), which reflects the volume rate of released accumulated bubbles, is calculated as  were transformed to trigonometric or logarithmic functions prior to testing for seasonal and spatial variability using one-way analysis of variance (ANOVA) and Tukey’s HSD test. Data were analysed using the SPSS statistical package .The flux in CHSI


It was 25 years later that the Group IV alternative σs were described as a distinct family of proteins related to σ70. In the intervening time, there has been an ever‐growing list of Group IV σs, numbers of genes they transcribe, insight into the diverse suite of processes they control, and appreciation for their impact on bacterial lifestyles. This work summarizes knowledge of the Rhodobacter sphaeroides σE‐ChrR pair, a member of the ECF11 subfamily of Group IV alternative σs, in protecting cells from the reactive oxygen species, singlet oxygen. It describes lessons learned from analyzing ChrR, a zinc‐dependent anti‐σ factor, that are generally applicable to Group IV σs and relevant to the response to single oxygen. This MicroReview also illustrates insights into stress responses in this and other bacteria that have been acquired by analyzing or modeling the activity of the σE‐ChrR across the bacterial phylogeny.This year marks the 50 1O2. The master regulator of this response, the Group IV ECF11 protein Rb. sphaeroides σE, directly activates transcription of ~genes, one (IIrpoH) encodes an alternative σ factor in the heat shock family. RpoHII directly activates ~145 genes; some 45 of which are also transcribed by RpoHI, the master regulator of the Rb. sphaeroides heat shock response.Activation of a cascade of alternative σ factors by the reactive oxygen species  However, when photosynthetic cells acquired the ability to produce O2, they altered the Earth's atmosphere and influenced the forms of life that inhabited the planet . 1O2 is known or predicted to peroxidize and eventually cleave unsaturated bonds in olefins, oxidize amino acid side chains or nucleic acid bases and cleave peptide or phosphodiester bonds , not travel far its site of synthesis, and produce localized damage  increases Rb. sphaeroides σE activity  that are often found together in nature   both contain similar α‐helical bundles despite the lack of significant primary amino acid sequence similarity between these proteins  interact with different regions of their cognate sigma factors, providing a way for each anti‐σ factor to recognize specific partner proteins  inhibited σE activity, but cells containing ChrR85 did not mount a transcriptional response to 1O2  and are not (187Cys and 189Cys) needed for 1O2 or the organoperoxide like t‐BOOH (see below) to increase σE activity  that responds to envelope stress  or t‐BOOH (occurs in cells lacking an intact ChrR‐CLD) do not occur by identical mechanisms  and in vivo  analyses, we found that 1O2 activated ~160 genes  were directly transcribed by σE‐containing RNA polymerase  that degrade ChrR, and the signal transduction pathway used to promote turnover of a cytoplasmic anti‐σ factor by a membrane ROS. In addition, identifying the function of genes that are directly transcribed by σE‐containing RNA polymerase but only found in selected species (extended members of the σE regulon) can provide needed insight into stress response functions associated with lifestyles or ecological niches of these bacteria.Despite the knowledge accumulated by studying It is crucial to point out that many of the above questions illustrate knowledge gaps for other Group IV alternative σs, so it is likely that answers obtained by analyzing ECF11 proteins will have broad applicability to other regulatory networks. In this way, analysis of the Group IV alternative σs will continue to illuminate new features of biological processes across the bacterial phylogeny.http://wwpdb.org/) under ID codes 2Q1Z, 2Z2S, and 1OR7. The gene expression and chromatin immunoprecipitation data sets discussed can be found in the Gene Expression Omnibus through series accession number GSE39806 (https://www.ncbi.nlm.nih.gov/geo/).The atomic coordinates for proteins discussed are deposited in the Protein Data Bank (


MYB clade of anthocyanin regulators in the genome of the purple flowering Petunia inflata S6 wild accession, and we called them ANTHOCYANIN SYNTHESIS REGULATOR (ASR). Two of these genes, ASR1 and ASR2, are inactivated by two different single base mutations in their coding sequence. All three of these genes are absent in the white flowering species P. axillaris N and P. parodii, in the red flowering P. exserta, and in several Petunia hybrida lines, including R27 and W115. P. violacea and other P. hybrida lines  instead harbor functional copies of the ASR genes. Comparative, functional and phylogenic analysis of anthocyanin R2R3‐MYB genes strongly suggest that the ASR genes cluster is a duplication of the genomic fragment containing the other three R2R3‐MYB genes with roles in pigmentation that were previously defined, the ANTHOCYANIN4‐DEEP PURPLE‐PURPLE HAZE (AN4‐DPL‐PHZ) cluster. An investigation of the genomic fragments containing anthocyanin MYBs in different Petunia accessions reveals that massive rearrangements have taken place, resulting in large differences in the regions surrounding these genes, even in closely related species. Yeast two‐hybrid assays showed that the ASR proteins can participate in the WMBW  anthocyanin regulatory complex by interacting with the transcription factors AN1 and AN11. All three ASRs can induce anthocyanin synthesis when ectopically expressed in P. hybrida lines, but ASR1 appeared to be the most effective. The expression patterns of ASR1 and ASR2 cover several different petunia tissues with higher expression at early stages of bud development. In contrast, ASR3 is only weakly expressed in the stigma, ovary, and anther filaments. The characterization of these novel ASRMYB genes completes the picture of the MYB members of the petunia anthocyanin regulatory MBW complex and suggests possible mechanisms of the diversification of pigmentation patterns during plant evolution.We identified three novel members of the R2R3‐ All of these genes encode similar proteins but differ in expression patterns controlling pigmentation in distinct tissues or under different conditions. AN2 is expressed in the petal limb and tube, whereas AN4 is expressed in the anthers at early developmental stages  based on multiple alignments of DNA or predicted amino acid sequences. The sequences of Arabidopsis genes were obtained from TAIR and those of other plants from other databases as referred to by the accession numbers. The accession numbers of all genes or proteins appearing in this paper are shown in Supporting Information Table The 2.3Solanaceae and Petunia were mined from the Sol Genomics Network (https://solgenomics.net/). We manually annotated some of the genes.All of the genomic data of 2.4ASR genes and other genes were amplified by PCR and the fragments were inserted into entry vectors  by BP reaction. The entry vectors were then used in recombination reactions with the destination vectors pK2GW2.0/rfa (OE), pKGWFS7.0/rfa (Promoter:GUS), pGBKT7/GW (Y2H), and pGADT7/GW (Y2H) by LR reaction. All constructs are described in Supporting Information Table All constructs in this study were made using the Gateway cloning system. The cDNA or gDNA of 2.5Agrobacterium tumefaciens strain Agl1. Stable transformants of Petunia hybrida M1×R27 or W115 were generated by Agrobacterium‐mediated leaf‐disc transformation. The regenerated plants were checked by PCR for the presence of the construct and by RT‐PCR for its expression.Constructs were transformed into 2.6pH measurements were performed as described previously . Anthocyanins were extracted using 50 mg of powdered petal (flower development stage 2–3) suspended in 5 ml of 0.5% (v/v) HCl‐methanol and incubated for 2 hr at 4°C in the dark. The extracts were then centrifuged for 15 min at 14,000 rpm, and the supernatants were collected and stored at −20°C. The supernatant was diluted with methanol to 5 ml and filtered through a cellulose acetate membrane . HPLC was performed with Agilent 1260 Infinity LC . Anthocyanidin profile analysis was quantified at the 530 nm wavelength by using a calibration curve from commercial standards of anthocyanidins .2.8®Premix Ex Taq™, Japan). Transcript abundance was calculated relative to actin by using the 2Ct−ΔΔ method. The primers used for these PCR analyses are listed in Supporting Information Table To determine the expression of the genes of interest, we analyzed their expression profiles by RT‐PCR or qRT‐PCR  methods. Total RNA was extracted via the TRIzol method, and its quantity and quality was measured by Nanodrop . cDNA synthesis was performed with PrimeScript™ II 1st Strand cDNA Synthesis Kit  and RT‐PCR analysis was carried out as previously described , 404 and 321 (pASR2), and 416 and 317 (pASR3). The promoters of ASR1 and ASR2 were isolated from the petunia M1 line using a Genome walking kit  with gene specific primers and the universal primer AP4. The promoters were amplified and cloned in front of the GUS reporter gene in the pKGWFS7.0/rfa vector using the Gateway system. M1×R27F1 hybrid petunia plants were used as hosts for the generation of stable transformants. Histochemical GUS staining was performed as described previously 6/K4Fe(CN)6) overnight at 37°C. Seedlings were then decolored by treatment with 70% ethanol.The promoters of the 2.102O, plated again on selective SC‐Leu/Trp/Ade/His medium at different dilutions , and grown for 2–4 days. All transformants containing BD‐ASR constructs displayed self‐activation . Therefore, only AD‐ASR constructs were used to test interactions with other proteins expressed as BD‐fusions.The BD or AD constructs for the expression of the fusion proteins in yeast were first transformed into the yeast strain AH109 and the yeast transformants were then screened by growth on SC‐Leu (for AD) or SC‐Trp (for BD) plates (2–3 days at 30°C). The transformant colonies that grew under these conditions were then used for cotransformation with the second construct for the interaction assay and plated on SC‐Leu/Trp media plates. Yeast double transformants were diluted in ddH33.1P. axillaris and P. inflata for anthocyanin R2R3‐MYBs resulted in the identification of three new members of this clade in P. inflata S6, which are absent in P. axillaris. Because of their similarity to known R2R3‐MYB anthocyanin regulators, we named these three genes ASR (ANTHOCYANIN SYNTHESIS REGULATOR). In the genome of P. inflata, these genes are arranged in a cluster (present within a single scaffold) , wild tomato (S. pennellii), and potato (S. tuberosum), with P. inflata and P. axillaris scaffolds containing AN2, AN4‐DPL‐PHZ, and ASR1‐ASR2‐ASR3 reveals some levels of shared synteny. The arrangement of the genes surrounding the MYB genes in all of these species supports their common origin suggested by the results of the phylogeny analysis and implicating a series of duplications that have generated the numerous members of this family in each Solanacea species. However, synteny analysis also suggests that many of these rearrangements took place in the short time separating these closely related species.R2R3‐MYB proteins, such as the petunia AN2, AN4, PHZ, and DPL  Figure a. All ths Figure b. ComparAN4 (and of some surrounding genes) in P. axillaris could be the reminiscence of the duplication that generated the ASR1, ASR2, ASR3 cluster, which in this lineage was followed by further rearrangements leading to partial loss of the cluster. Even though both P. axillaris and P. inflata contain a copy of the AN2 gene, these genes are contained in genomic fragments that were rearranged, resulting in a different distribution of surrounding genes in the two species. For example, on the right of AN2, the serine protease family protein (25), ARMADILLO/BETA‐CATENIN repeat family protein (26), and the serine/threonine protein kinase (27), are conserved, but their positions were rearranged. In addition, the P. axillaris AN2 allele contains a mutation that destroys the coding sequence  are missing in P. parodii and P. exserta. Therefore, it is not surprising that some Petunia hybrida lines, generated by repeated crosses among different wild species, have the genomic fragments containing these three genes  and others do not (W115 and R27)  the Petunia hybrida lines were generated.Analysis of different petunia wild species revealed that all three ) Figure . In P. iASR1‐ASR2‐ASR3 cluster from P. inflata and the P. hybrida line M1 shows several rearrangements. As shown in Figure ASR genes in P. inflata and in the P. hybrida line M1 reveals a 675 bp insertion present in the ASR1M1 promoter region, approximately 1,500 bp upstream of the start codon. The ASR2M1 promoter contains instead an 850 bp fragment, similar to a fragment of the ASR1 promoter. An 860 bp insertion is also found in the second intron of ASR1M1.The phylogenic tree of the deduced amino acid sequences of ASRs and other R2R3‐MYBs in petunia further confirms that they encode SG6 MYBs and indicates that the different members of this group originate from duplications of a common ancestor and subsequent independent rearrangements in the different petunia species  lines containing constructs in which the coding sequences  are expressed from the CaMV35S promoter. As a host, we used the F1 hybrid between the two P. hybrida lines M1 and R27. Over 50 independent lines were generated for each construct. As shown in Figure ASR1M1‐OE, ASR2M1‐OE, ASR3M1‐OE, and ASR3inf‐OE were pigmented, which was not observed for ASR1inf‐OE and ASR2inf‐OE as predicted because ASR1inf and ASR2inf encode truncated proteins. In the ASRsM1‐OE lines, flower buds showed pigmentation in very early stages of floral development when buds of the untransformed control are completely acyanic. However, after the buds opened, pigmentation did not differ significantly from that of the untransformed control lines. AN2 reaches high expression in petals shortly before bud opening  but does not contribute to increasing it further in the open flowers. Although overexpression of each of the three ASR genes affected pigmentation, ASR1M1‐OE plants showed the most intense pigmentation, which included the stamens, stamen filaments, and gynoecium of the flower  showed that all three of them, as well as AN2, AN4, DPL, and PHZ, contain the conserved [DLx2Rx3Lx6Lx3] motif required for interactions with bHLH proteins  with AN1 and AN11. This assay showed that the ASRs interact with both AN1 and AN11 , operating in the pathway starting from the step controlled by DFR, are strongly activated by the ASR regulators. However, the expression of the EBGs (Early Biosynthetic Genes), C4Ha, CHIa, 4CLa, and F3′H, were not affected. The Methylation at Five (MF) gene  was induced in ASRs‐OE lines, and no induction was observed for the expression of PH1 and PH5, the two P‐ATPases required for vacuolar hyperacidification in the epidermis of petals . Both petals and anthers of the flowers are acyanic in this line; therefore, the contribution of ASR genes to the pigmentation of flower organs can be more easily assessed in this genetic background. All lines ectopically expressing ASRsM1 in W115 had dusky bronze vegetative organs; ASR1M1‐OE plants were the most intensely pigmented and ASR2M1‐OE plants the least  pigmented, whereas the filaments and pistils did not differ in color from those of the untransformed controls. In addition, the seed pods in the early stages of development are pigmented in ASRsM1 overexpression lines in this background, while in the M1×R27 background, this finding was not observed, probably due to the weak hf1 allele   genomes participated in the breeding of Petunia hybrida and that the M1 allele originated from one of those. In fact, the wild petunia species P. violacea probably contains two copies of the ASR cluster, one of which contains ASR genes similar to the alleles found in the P. hybrida line M1 and the other genes containing the same mutations found in the P. inflata ASR cluster. This again supports the idea that patterns of coloration in petunia have been generated by repeated gain (and maybe loss) of new regulators occurring by duplications and differentiation of MYB genes, as well as by repeated loss of function for some of these copies. The differences in promoter regions, the expression patterns of single SG6 MYB genes in petunia, and the effect of mutation and overexpression reported here and in previous studies have shown that these genes differentiated substantially from each other. They can confer pigmentation to different tissues and under different conditions and result in the activation of a partially different set of target genes in the anthocyanin pathway.The PH4 gene  can take part in the WMBW complex, conferring on it large flexibility in target gene specificity and giving rise to a never‐ending variation in pigmentation patterns via the activation of genes involved in the synthesis of different pigments and copigments and acidification of the vacuolar lumen where the pigments are accumulated (ref. PH4 and ref. TT2).All of these MYBs are closely related to each other but differentiated in (a) their function, as they activate distinct sets of target genes, and (b) their expression patterns. The differences in sets of target genes for different MYB members of the WMBW complex are probably not merely due to the evolution of the promoters of the target genes. The acquired specificity is supported by the observation that MYBs of the SG6 clade cannot activate the PH4 targets ASR1, ASR2, and ASR3 completes the picture of the petunia MYB genes involved in processes related to the differentiation of petal epidermal cells. These three genes can participate in the formation of WMBW complexes, probably playing a role in the acquisition of pigmentation in very young buds and in other plant parts when these are exposed to very high light. The presence in all plants of numerous genes encoding similar MYB proteins associated with strong rearrangement activity of the genomic region around them provides a genetic basis for the generation of new patterns of pigmentation and might have contributed to the differentiation of species within the Petunia genus by affecting their pollination syndromes.Thus, the characterization of the new R2R3‐MYB cluster containing the genes Sequence data from this paper have been deposited in GenBank , and J.G. completed gene identification and sequence analysis, X.D. and H. W. cared for the plants, J.Z. and V. P. performed DNA and RNA experiments, H. J. and Z.F. performed RT‐PCR analysis, Y.L (Yanmin Li) generated the transgenic petunia. Click here for additional data file. Click here for additional data file. Click here for additional data file.


BiI3 is deposited by molecular beam epitaxy from the crystalline BiTeI precursor that undergoes decomposition sublimation. The key fragment of the bulk BiI3 structure, 6 octahedra, is preserved in the ultra-thin film limit, but exhibits large atomic relaxations. The stacking sequence of the trilayers and alternations of the Bi—I distances in the monosheet are the same as in the bulk BiI3 structure. Momentum resolved photoemission spectroscopy indicates a direct band gap of 1.2 eV. The Dirac surface state is completely destroyed and a new flat band appears in the band gap of the BiI3 film that could be interpreted as an interface state.A stable BiI Bulk BiI3 belongs to the inversion symmetric space group ABC sequence3. Bulk BiI3 is an indirect band gap semiconductor with a gap width of 1.67 eV1 which is favorable for potential energy harvesting4. Owing to the presence of a high-Z element (Bi) spin-orbit coupling (SOC) is significant and new functionalities are expected by reducing the crystal’s dimensionality to the ultra-thin film limit which might involve a symmetry lowering, for instance by the loss of the inversion center induced by atomic relaxations.The periodic structure of BiI3 monosheets have been carried out which have predicted its stability and the possibility to tune the band structure by strain5. However, no experimental investigation concerning structure and physical properties of BiI3 monosheets are available. One standard way to prepare a thin film of a layered material is cleaving the bulk crystal which in the case of BiI3 consists of weakly van-der-Waals (vdW) connected sheets. Its disadvantage is that this method neither allows precise control of the film thickness nor the preparation of a single monosheet. Furthermore, handling of bulk BiI3 is hindered due to its notable moisture-sensitivity.Up to now, only theoretical studies on BiI3 on the (0001) surface of the topological insulator (TI) Bi2Se3 by using molecular beam epitaxy (MBE) from a Knudsen cell filled with presynthesized BiTeI single crystals heated to 380 °C. As a result, a stoichiometrically almost exact BiI3 film is deposited by decomposition sublimation of BiTeI, as corroborated by X-ray photoemission spectroscopy (XPS), scanning tunnelling microscopy (STM) and surface X-ray diffraction (SXRD). In addition, momentum resolved photoemission spectroscopy6 demonstrates the instability of the Dirac topological surface state (TSS) of the Bi2Se3 substrate upon BiI3 deposition and the appearance of flat band interface states in the direct band gap of BiI3.Here we establish a different approach by depositing a monosheet of BiIin-situ in ultra-high-vacuum systems equipped with standard surface physics analytical tools.Experiments were carried out 3 was MBE-deposited onto the substrate that was kept at room temperature. The underlying mechanism can be rationalized by decomposition sublimation of BiTeI9: 2Te3 and gaseous BiI38. This is a typical behavior of chalcogenide halides9. The remaining Bi2Te3 may decompose further, forming subsidiary BiTe and Te2 gas species: Figure 2Te3 can proceed as an alternative reaction with these species:Vapor transport of both BiTeI and Bi2(g) increase sufficiently only above 410 °C and can then promote efficient vapor transport7. At our working temperatures, the total pressure is largely dominated by BiI3 gas species for a broad range of compositions in the ternary Bi-Te-I phase diagram10.However, the partial pressures of BiI(g) and Te3 film on the Bi2Se3 substrate was observed via appearance of new LEED spots that closely corresponded to a √3 × √3-R30° superstructure, as shown in Fig. 3 on Bi2Se3 is feasible thanks to a close structural match between the bulk structures. Both crystal structures can be viewed as hexagonal close-packed arrangements of anions (either iodine or selenium) with cations (bismuth) occupying the octahedral voids in a regular fashion. In the tetradymite-type structure, like Bi2Se3, two consecutive rows of octahedral voids along the c axis are fully populated and each third row remains empty, thus forming a van der Waals (vdW) gap between the quintuple layers (QL), ABC-sequence12. In BiI3, 2/3 of the octahedral sites within each second row of cations along the stacking direction are occupied. In the case of ideally matching lattices, BiI3 would exhibit a √3 × √3-R30° superstructure in the ab-plane with respect to the Bi2Se3 (0001) − (1 × 1) surface unit cell. But the existing difference in the van der Waals radii (Se: 1.82 Å vs. I: 2.04 Å) constitutes a mismatch between the anionic lattices, that becomes evident from the comparison of the respective unit cell parameters a: whereas a(Bi2Se3) = 4.134(2) Å13, a(BiI3) = 7.5249(3) Å3 is about 0.3 Å larger than a(Bi2Se3)√3. The detailed SXRD analysis of the deposited BiI3 indicates that the first order spot is located at h = k = 0.316 units of the hexagonal Bi2Se3 reciprocal surface lattice, rather than at 3 film is incommensurate with the substrate just like in the bulk case. Moreover, the mismatch is even stronger in the film, since the adlayer has an in-plane lattice parameter of a0 = 7.56 Å as compared to the reported range of bulk values which lie between a0 = 7.5249 Å and 7.50 Å15. We note that the lateral strain is only +0.8% at most and is thus well below the computed breaking strain of 13% for a free standing monosheet5.Formation of a BiI2 STM image  of a single-layer BiI3 film. The profile along the white line (labelled by “1”) is plotted in (b). The surface of the Bi2Se3 single crystal is characterized by 9.5 Å high steps which correspond to a full QL. The BiI3 monosheet has about 7 Å high steps corresponding to 1/3 of the bulk c0 lattice parameter of 20.72 Å related to three triple layers (TL)14. The wetting of the Bi2Se3 terraces proceeds from the step edges, leaving 3 Å high steps between the BiI3 layer and the next terrace.Figure 3 deposition, the first-order (h = k = 0.316) reflection intensity was monitored until saturation. Subsequently, reflection intensities along several lattice rods were collected under grazing incidence (αi = 2°) of the incoming beam. In total 1042 symmetry independent reflections were collected along six lattice rods which are shown as symbols in Fig. 16 that enables refinement of anisotropic and anharmonic displacement parameters17 and crystal twinning. The latter is especially relevant in the present case owing to the two possible orientations of the adsorbate lattice relative to the substrate lattice, that forge the 6 mm point symmetry of the experimental diffraction pattern. In the plane group p3, bismuth atoms occupy the Wyckoff positions 1a, 1b, 1c, while iodine atoms reside in the general position 3d. Note that the plane group p3 lacks inversion symmetry in contrast to the space group 3 layers in the periodic structure3. The refined atomic coordinates and the isotropic displacement parameters (B = 8π2 <u>2) for the adlayer are listed in Table Iobs, Icalc are the experimental and calculated intensities, respectively and the summation runs over all datapoints. The GOF is given by: σ) and to (N − P), i.e. the difference between the number of independent data points (N) and the number of parameters (P) which are varied. Here, we derive GOF = 1.40 and RU = 0.14, which are very reasonable values in view of the weak intensities scattered by the monosheet.The atomic structure of the deposited film was analyzed by SXRD experiments which were carried out at the beamline SpLine BM25b of the European Synchrotron Radiation Facility in Grenoble (France) using a UHV six-circle diffractometer equipped with a two-dimensional pixel detector. During BiI33. At first, the analysis shows that there is one complete TL and approximately one half of a second TL on the Bi2Se3 surface. Thus, in comparison with the STM experiments which indicated a single TL only, this sample is covered by BiI3 at its saturation coverage at 300 K. It can be concluded that the interlayer interaction is very weak which is also corroborated by the fact that desorption of the whole film sets in at about 360 K as evidenced by the rapid loss of the BiI3 reflection intensities. Correspondingly, the vertical spacing between the first and the half filled second TL is considerably enlarged as compared to the bulk. For instance, the closest interlayer I–I distance across the vdW gap increases from 4.14 Å in the bulk to 4.8 Å in the film.Figure 3+: 1.03 Å vs. I−: 1.70 Å) radii19 imposes limits of 3.86 Å and 2.73 Å for the Bi–I interatomic distance for atomic and ionic bonds, respectively. The distances derived from the SXRD analysis suggest a considerable ionicity of the Bi–I bond.The SXRD analysis also finds considerable relaxations within the TL’s. The first TL adjacent to the substrate is notably stretched as compared to its bulk counterpart, namely, the interplanar distance between the terminating iodine atoms  increases from 3.61 Å (bulk) to 3.89 Å. The interatomic Bi–I distances towards the substrate 3.32–3.44 Å) are considerably longer than in the opposite direction (2.94–3.00 Å). All bismuth atoms . After film deposition at room temperature until saturation as in the case of the SXRD experiments the sample was kept at 130 K using s-polarized light and a photon energy of hν = 200 eV. Figure 3 saturated Bi2Se3 (0001) surface. In the case of the pristine sample, the spin-orbit split Bi-5d  and the Se-3d  are observed.Owing to their very similar atomic number, X-ray diffraction is not capable to separate the atomic species iodine Z = 53) and tellurium (Z = 52). X-ray photoemission spectroscopy was used to analyze the chemical composition of the film. All photoemission spectroscopy experiments were carried out at the NanoESCA beamline3 and telB = 49.0 [4d5/2] and 50.8 eV [4d3/2]) and tellurium (EB = 40.1 [4d5/2] and 41.6 eV [4d3/2]) appear. For a quantitative evaluation, the core level peaks were fitted using Voigt line shapes, taking into account the natural line width and the instrumental resolution, on top of a Shirley background. The fitted peak areas were subsequently corrected on the basis of tabulated photoionization cross sections and by a polarization factor for the photon energy of hν = 200 eV used for the XPS measurement21. This results in the normalized intensities of I(Se-3d3/2) = 1, I(I-4d3/2) = 2.2, I(Te-4d3/2) = 0.07, and I(Bi-5d3/2) = 2.3. Thus, the tellurium contribution in the film equals to only about 3% of that of the iodine contribution, indicating that the film is almost pure BiI3. In particular, the tellurium concentration is far away from that in stoichiometric BiTeI, for which the tellurium and iodine 4d signals are expected to be very similar.After film deposition in addition the 4d lines of iodine , respectively. The latter corresponds to a complete BiI3 triple layer plus a second one which covers about a half of the surface area as found in the SXRD analysis. For pristine Bi2Se3(0001), the nearly linearly dispersive Dirac topological surface state (TSS) is clearly observed. Owing to the selenium vacancy induced n-doping, the Dirac point (DP) lies approximately 400 meV below the Fermi energy (EF).Figures 3 adsorption, strong modifications of the band structure are observed. Fist of all, the TSS as such is destroyed and a new almost dispersion-less band appears at a binding energy (EB) of approximately −1.2 eV below EF. In the energy range between E = EF and E = −0.7 eV two states at 3. For comparison Fig. 3 film including the atomic relaxations derived by the SXRD experiments. Our SXRD data suggest that the saturation film thickness is about one and a half TL’s. That is why we have chosen the calculation related to the two TL thick film for direct comparison with experiment.Upon BiI5 and is separated from the conduction band (CB) by a gap of approximately Eg = 1.2 eV, which can be considered to be direct owing to the flat band conditions in the vicinity of the 3 can also be identified in the momentum resolved photoemission experiment, which has a considerably smaller dispersion as the calculated one for the free-standing two TL thick film. We note that the calculated band structure for a single TL film  via: |Fobs(hkl)|2 = Iobs(hkl) × Ccorr. Subsequently, the |Fobs(hkl)|2 were averaged according to the p3 plane group symmetry of the (0001) surface leading to in total 1042 symmetry independent |Fobs(hkl)|2. The total uncertainty (1 σ) is estimated by the quadrature sum of the statistical and the systematic error as outlined e.g. in ref.27. We find the reproducibility of symmetry equivalent |Fobs(hkl)|2 is equal to 17%.Surface X-ray diffraction experiments were carried out at the beamline BM25b of the European Synchrotron Radiation Facility in Grenoble (France) using a six-circle UHV diffractometer. Samples were prepared 3 deposition on pristine Bi2Se3(0001) surface. Here, p-polarized light with a photon energy of hν = 40 eV was used. The incident photon beam lies in the ky–kz plane at an angle of 25° above the surface plane. By utilizing momentum microscopy, the wide acceptance angle of photoelectrons of ±90° can be simultaneously collected over a hemispherical region in real space. This provides full access to directly probe two-dimensional  reciprocal-space momentum maps of the photoemission intensity throughout the entire surface Brillouin zone (SBZ). Furthermore, by scanning the binding energy EB, the complete information of three-dimensional EB maps, containing band dispersion along all directions of the SBZ, can be obtained28.Momentum-resolved photoemission spectroscopy experiments were carried out to study the electronic states upon BiI30. The calculations were performed within the density functional theory in a generalized gradient approximation31. The angular momentum cutoff was taken to be lmax = 3 and a Γ-centered (30 × 30 × 12) k-mesh was used.First-principles simulations have been carried out using a full-potential full-relativistic Green function method within the multiple scattering theory, specially designed as for bulks and for semiinfinite systems such as surfaces and interfaces