Search

The bHLH transcription factors play pivotal roles in plant growth and development, production of secondary metabolites and responses to various environmental stresses. Although the bHLH genes have been well studied in model plant species, a comprehensive investigation of the bHLH genes is required for tobacco with newly obtained high-quality genome. In the present study, a total of 309 NtbHLH genes were identified and can be divided into 23 subfamilies. The conserved amino acids which are essential for their function were predicted for the NtbHLH proteins. Moreover, the NtbHLH genes were conserved during evolution through analyzing the gene structures and conserved motifs. A total of 265 NtbHLH genes were localized in the 24 tobacco chromosomes while the remained 44 NtbHLH genes were mapped to the scaffolds due to the complexity of tobacco genome. Moreover, transcripts of NtbHLH genes were obviously tissue-specific expressed from the gene-chip data from 23 tobacco tissues, and expressions of 20 random selected NtbHLH genes were further confirmed by quantitative real-time PCR, indicating their potential functions in the plant growth and development. Importantly, overexpressed NtbHLH86 gene confers improve drought tolerance in tobacco indicating that it might be involved in the regulation of drought stress. Therefore, our findings here provide a valuable information on the characterization of NtbHLH genes and further investigation of their functions in tobacco.

Despite their high theoretical energy density, the application of lithium-sulfur batteries is seriously hindered by the polysulfide shuttle and sluggish kinetics, especially with high sulfur loading and under low electrolyte usage. Herein, to facilitate the conversion of lithium polysulfides, nickel-boron (Ni-B) alloy nanoparticles, dispersed uniformly on carbon nanotube microspheres (CNTMs), are used as sulfur hosts for lithium-sulfur batteries. It is demonstrated that Ni-B alloy nanoparticles can not only anchor polysulfides through Ni-S and B-S interactions but also exhibit high electrocatalytic capability toward the conversion of intermediate polysulfide species. In addition, the intertwined CNT microspheres provide an additional conductive scaffold in response to the fast electrochemical redox. The enhanced redox kinetics is beneficial to improve the specific capacity and cycling stability of the sulfur cathode, based on the fast conversion of lithium polysulfides and effective deposition of the final sulfide products. Conclusively, the S/Ni-B/CNTM composite delivers a high specific capacity (1112.7 mAh gs-1) along with good cycle performance under both high sulfur loading (8.3 mg cm-2) and a lean electrolyte (3 μL mgs-1). Consequently, this study opens up a path to design new sulfur hosts toward lithium-sulfur batteries.

Mizoroki-Heck reaction of unstrained aryl ketone with acrylate/styrene is accomplished via palladium-catalyzed ligand-promoted C-C bond cleavage. Various (hetero)aryl ketones are compatible in the reaction, affording the alkene product in good to excellent yields. Further applications in the late-stage olefination of some drugs, natural products, and fragrance-derived aryl ketones demonstrate the synthetic utility of this protocol. By employing ketone as both the directing group and the leaving group, 1,2-bifunctionalization is achieved via sequential ortho-C-H alkylation/ipso-Heck olefination.

Conversion of the numerous aryl ketones into aryl electrophiles via Ar–C(O) cleavage remains a challenging yet highly desirable transformation in Sonogashira-type coupling. Herein, we report a pall...

Effective hosts of sulfur are essential for the application of lithium-sulfur batteries. However, various refined nanomaterials or carbon-based hosts possess low density, high surface area, and large porosity, leading to undesirable reduction on both gravimetric and volumetric energy densities. Herein, spherical metal oxides with high tap density are introduced as carbon-free hosts of sulfur for the first time. The ternary oxides show a superior synergistic effect of adsorption and electrocatalytic conversion of soluble intermediate polysulfides. Besides, oxide microspheres can build stable conductive frameworks and open channels in porous electrodes for fast transport of electrons and active diffusion of electrolyte. Such a synergistic effect and unique structural feature of porous electrodes are favorable for achieving good utilization and stable cycle performance of the sulfur cathode. Typically, the S/LiNi0.8Co0.1Mn0.1O2 composite exhibits good cycle stability with a low capacity decay rate (0.057% per cycle) during 500 cycles at 0.1 C. Importantly, due to the high tap density (1.81 g cm-3), the S/LiNi0.8Co0.1Mn0.1O2 composite delivers a larger volumetric capacity (1601.9 mAh cm-3-composite), almost 2.3 times of S/carbon composite (689.4 mAh cm-3-composite). Therefore, this work provides a feasible strategy to reach long life and high volumetric capacity of cathode based on metal oxides as sulfur hosts.

Standards GB 150.3-2011 and JB4732-1995 (Confirmed in 2005) provide design methods for the cylindrical pressure vessels with spherically dished head under internal pressure. It is available for the ratio of the internal pressure p to the allowable stress Sm, p/Sm≥0.002. Engineers desire the design curves for p/Sm

Giant liposome is an important lipid structure widely used in biological and medical fields. In its main preparation method, electroformation, many influencing factors must be optimized for good effect. How to collect the desired giant liposomes is another major issue. In this work, a microchip with a reactor chamber array was used to study the influences of multiple parameters, and a suitable condition could be achieved rapidly and efficiently. A tailor-made collection chamber was also integrated on the chip. Based on the multifactor and multilevel orthogonal experiment, optimal conditions of the lipid solution, buffer solution, and electric signal were achieved with high efficiency. More than one thousand giant liposomes could be formed in each microscale reactor chamber, and most of them were unilamellar. The on-chip collection ratio of giant liposome carriers could also approximate to 40%.

Interleukin 8 is known as an important chemokine and plays an important role in tumor growth and angiogenesis. Over expression of IL-8 has been detected in a variety of human tumors, including gastric cancer and breast cancer. Therefore, the development of rapid and sensitive profiling methods is crucial for evaluating the level of IL-8 expression in human serum, which is related to normal and tumor states. In our study, surface-enhanced Raman scattering (SERS) based on the double antibody sandwich format is reported for the determination of IL-8. Highly-branched gold nanoparticle (HGNP) substrates were fabricated and conjugated with anti-IL-8 (coating) as capturing substrates, and gold nanocages (GNCs) adsorbed with 4-mercaptobenzoic acid are modified with anti-IL-8 (labeling) as SERS tags. After the substrates captured IL-8, the SERS tags were bonded to the captured IL-8. The interaction of the SERS capturing substrates (HGNPs) and the SERS tags (GNCs) shows high sensitivity and a low detection limit for IL-8. The linear dynamic range of SERS for IL-8 was from 10 pg mL−1 to 1 μg mL−1, which shows a linear relationship between IL-8 concentration and SERS intensity. The detection limit was 6.04 pg mL−1 in phosphate buffered saline and 6.88 pg mL−1 in human serum. The analysis results of serum samples obtained from healthy subjects and two different types of cancer patients (breast cancer and gastric cancer) by using the SERS method were acceptably consistent with those obtained by the enzyme-linked immunosorbent assay. The proposed immunoassay shows great potential for application in clinical diagnosis.

Cytochrome P450 2C9 (CYP2C9) is capable of catalyzing the biotransformation of endogenous compounds in cells, indicating that this enzyme could change the intracellular environment and is related to the pathogenesis of diseases. Currently, it is still a challenge to study the differences in cellular components between CYP2C9-expressing and non-expressing cells. In this study, employing a Au nanoparticles–Ag nanowires (AuNPs–AgNWs) decorated silicon wafer as a novel non-destructive and label-free tool, we applied surface-enhanced Raman scattering (SERS) spectroscopy to detect and distinguish the cellular composition of CYP2C9-expressing cells (293T-Mig-2C9) and non-expressing cells (293T-Mig-R1). AgNWs with high surface roughness were formed by modification of AuNPs onto their surface by electrostatic interactions, which enabled them to exhibit greatly enhanced SERS ability. Then, they were employed to fabricate SERS substrates via an electrostatically assisted 3-aminopropyltriethoxysilane (APTES)-functionalized surface-assembly method. The SERS substrates exhibited high sensitivity with a detection limit of 1 × 10−9 M for 4-mercaptobenzoic acid (4-MBA). Meanwhile, the SERS substrates exhibited good uniformity and reproducibility. The cytotoxicity assay demonstrated that the SERS substrates displayed good biocompatibility with 293T cells. Before SERS measurements, CYP2C9 constantly expressed cells (293T-Mig-2C9 cells) and control cells (293T-Mig-R1 cells) were constructed. The expression of CYP2C9 and the catalytic activity in the cells were checked. Using the AuNPs–AgNWs substrates as a high-performance in vitro sensing platform allowed us to obtain fingerprint spectra of 293T-Mig-R1 and 293T-Mig-2C9 cells. The difference spectra between the two cell lines were studied to interpret the spectral differences and gain insight into the biochemical variations. Finally, principal component analysis (PCA) score plots of the SERS spectra were also used to better view the differences between the two cell lines. SERS detection based on the AuNPs–AgNWs substrates provides a sensitive, non-destructive and label-free method for differentiation between 293T-Mig-R1 and 293T-Mig-2C9 cells.

The coupling of aromatic electrophiles (aryl halides, aryl ethers, aryl acids, aryl nitriles etc.) with nucleophiles is a core methodology for the synthesis of aryl compounds. Transformations of aryl ketones in an analogous manner via carbon-carbon bond activation could greatly expand the toolbox for the synthesis of aryl compounds due to the abundance of aryl ketones. An exploratory study of this approach is typically based on carbon-carbon cleavage triggered by ring-strain release and chelation assistance, and the products are also limited to a specific structural motif. Here we report a ligand-promoted β-carbon elimination strategy to activate the carbon-carbon bonds, which results in a range of transformations of aryl ketones, leading to useful aryl borates, and also to biaryls, aryl nitriles, and aryl alkenes. The use of a pyridine-oxazoline ligand is crucial for this catalytic transformation. A gram-scale borylation reaction of an aryl ketone via a simple one-pot operation is reported. The potential utility of this strategy is also demonstrated by the late-stage diversification of drug molecules probenecid, adapalene, and desoxyestrone, the fragrance tonalid as well as the natural product apocynin.

Biosurfactants exhibit outstanding interfacial properties and unique biological activities that fairly related to their self-assembly in solutions and at interfaces. Computational simulations provide structural details of biosurfactant aggregates at the molecular level relevant to thermodynamic properties, but the understanding of kinetics of self-assembly remains limited due to lower simulation efficiency. In this work, a coarse-grained model has been developed for microbial lipopeptide surfactin, and surfactin monolayer at the octane/water interface and micelle in aqueous solution were studied using molecular dynamics simulations. Interaction parameters were optimized and validated by comparing with results obtained from experiments and atomistic molecular dynamics simulations. In particular, self-assembly of surfactin in aqueous solution was studied using the optimized parameters. Results showed that coarse-grained simulations well reproduced structural properties of surfactin monolayer and micelle and the molecular behavior such as surfactin orientation and conformation. Self-assembly features of surfactin in different stages have been captured, and the aggregation numbers of dominant clusters were in accordance with experimental data. This report suggested that the present coarse-grained model and interaction parameters allowed surfactin simulations over longer timescales and larger systems, which provide insights into characterizing both the kinetics of surfactin self-assembly and the adsorption of surfactin onto varying interfaces.

Biocompatible nanoscale probes for sensitive detection of paramagnetic species and molecules associated with their (bio)chemical transformations would provide a desirable tool for a better understanding of cellular redox processes. Here, we describe an analytical tool based on quantum sensing techniques. We magnetically coupled negatively charged nitrogen-vacancy (NV) centers in nanodiamonds (NDs) with nitroxide radicals present in a bioinert polymer coating of the NDs. We demonstrated that the T1 spin relaxation time of NV centers is very sensitive to the number of nitroxide radicals, with a resolution down to ~10 spins per ND (detection of approximately $ 10^-23 $ mol in a localized volume). The detection is based on T1 shortening upon the radical attachment and we propose a theoretical model describing this phenomenon. We further show this colloidally stable, water-soluble system can be used dynamically for spatiotemporal readout of a redox chemical process (oxidation of ascorbic acid) occurring near the ND surface in an aqueous environment under ambient conditions., Comment: 26 pages (plus 18 pages of supporting information), 3 figures (plus 8 figures in supporting information)

Due to their long coherence times, nuclear spins have gained considerable attention as physical qubits. Two-qubit gates between nuclear spins of distinct resonance frequencies can be mediated by electron spins, usually employing a sequence of electron-nuclear gates. Here we present a different approach inspired by, but not limited to, NV centers in diamond and discuss possible applications. To this end we generalize external electron spin control sequences for nuclear spin initialization and hyperpolarization to achieve the simultaneous control of distinct nuclear spins via an electron spin. This approach results in efficient entangling gates that, compared to standard techniques, reduce the gate time by more than 50% when the gate time is limited by off-resonant coupling to other spins, and by up to 22% when the gate time is limited by small electron-nuclear coupling., Comment: 9+4 pages, 4+2 figures

The rare earth elements (REEs) have unique and diverse properties that make them function as an “industrial vitamin” and thus, many countries consider them as strategically important resources. China, responsible for more than 60% of the world’s REE production, is one of the REE-rich countries in the world. Most REE (especially light rare earth elements (LREE)) deposits are closely related to carbonatite in China. Such a type of deposit may also contain appreciable amounts of industrially critical metals, such as Nb, Th and Sc. According to the genesis, the carbonatite-related REE deposits can be divided into three types: primary magmatic type, hydrothermal type and carbonatite weathering-crust type. This paper provides an overview of the carbonatite-related endogenetic REE deposits, i.e., primary magmatic type and hydrothermal type. The carbonatite-related endogenetic REE deposits are mainly distributed in continental margin depression or rift belts, e.g., Bayan Obo REE-Nb-Fe deposit, and orogenic belts on the margin of craton such as the Miaoya Nb-REE deposit. The genesis of carbonatite-related endogenetic REE deposits is still debated. It is generally believed that the carbonatite magma is originated from the low-degree partial melting of the mantle. During the evolution process, the carbonatite rocks or dykes rich in REE were formed through the immiscibility of carbonate-silicate magma and fractional crystallization of carbonate minerals from carbonatite magma. The ore-forming elements are mainly sourced from primitive mantle, with possible contribution of crustal materials that carry a large amount of REE. In the magmatic-hydrothermal system, REEs migrate in the form of complexes, and precipitate corresponding to changes of temperature, pressure, pH and composition of the fluids. A simple magmatic evolution process cannot ensure massive enrichment of REE to economic values. Fractional crystallization of carbonate minerals and immiscibility of melts and hydrothermal fluids in the hydrothermal evolution stage play an important role in upgrading the REE mineralization. Future work of experimental petrology will be fundamental to understand the partitioning behaviors of REE in magmatic-hydrothermal system through simulation of the metallogenic geological environment. Applying “comparative metallogeny” methods to investigate both REE fertile and barren carbonatites will enhance the understanding of factors controlling the fertility.

Ubiquitous light emitting dioxides provide natural infrastructures for multiuser visible light communications (VLC). The current available works mainly focus on a potential assumption of the continuous signaling. In this paper, we consider a two-user multiaccess VLC system with finite-alphabet inputs. To manage the nonnegative finite-alphabet multiuser interference, we adaptively adjust the power of each user's transmitted signals to maximize the received minimum Euclidean distance. By applying the properties of Farey sequence in number theory to solve the finite-alphabet optimization, it is proved that the optimal received signal constitutes an equally spaced pulse amplitude modulation constellation, which admits a low-complexity maximum likelihood detection. Both analytical results and computer simulations demonstrate that our proposed design has substantial performance advantage over time division multiple access, especially for significant channel strength difference.

An efficient nickel-catalyzed reductive relay cross-coupling of internal alkenes with alkyl (or aryl) halides has been developed. This method has demonstrated broad substrate scope, mild reaction conditions and excellent terminal-selectivity. Moreover, this efficient strategy could be applied to the terminal-selective alkylation of isomeric mixtures of internal alkenes.

An efficient nickel-catalyzed Heck-type reaction between styrenes and fluoroalkyl iodine has been developed. This novel transformation has demonstrated a broad substrate scope, mild reaction conditions and excellent E-stereoselectivity. This efficient synthetic method has been applied to the late-stage monofluoroacetation of biologically active molecules. Mechanistic investigations indicate that a monofluoroalkyl radical is involved in the catalytic cycle.

The mushroom growth of portable intelligent devices and electric vehicles put forward higher requirements for the energy density and safety of rechargeable secondary batteries. Lithium-ion batteries using solid-state electrolytes are considered to be the most promising direction to achieve these goals. This review summarizes the foremost challenges in line with the type of solid electrolyte, provides a comprehensive overview of the advance developments in optimizing the performance of solid electrolytes, and indicates the direction for the future research direction of solid-state batteries and advancing industrialization.

Bio-based zwitterionic surfactants have received increasing attention owing to their structural diversity and good interfacial activity. Therefore, understanding the relationship between the structure of bio-based zwitterionic surfactants and interfacial behaviors has significance for its industrial applications. In this study, molecular dynamics simulation was employed to investigate the interfacial behaviors of bio-based zwitterionic surfactants (BZS) with seven structures at the air/water interface. The four of them were isomers of BZS, in which the phenyl groups were located at the 7-, 10-, 13-, and 16- carbon atom of the octadecanoyl group. The other three were the homologues of 10B, and were different in the structures of hydrophilic groups. The structure-property relationship was demonstrated by the structure of surfactant monolayer, the overall arrangement of surfactant molecules at the interface, and the dynamic properties of binding pairs between surfactant and water/cations. The results showed that waved monolayers were formed when the phenyl group located at the 7- carbon atom of the hydrophobic tail of BZS, and there were more hydration water and cations surrounding the hydrophilic group of surfactants. As for the surfactants with the phenyl group located at 16- of the hydrophobic tail of BZS, molecules were arranged more perpendicular at the interface and formed a flat monolayer and construct stable binding pairs with water and cations. Morphology of monolayer and molecular orientation were independent of the change in structure of headgroup, but surfactant with less methylene on the hydrophilic group had the less steric hindrance, which induced more hydration water, more neighboring surfactants, and more stable of binding pairs between COO- and water.

Ru-catalyzed directed o-C–H arylation reactions of 2-phenylpyridine, N-phenylpyrazole, acetophenone N-(p-methoxyphenyl)imine, and 2-phenyloxazoline proceed in good to excellent yields with a number of functionalized aryl and heteroaryl bromides in neat Bu4NOAc at 120 °C. The acetate ion acts as the base and the relatively low melting point Bu4N salts (a mixture of acetate and bromide) behave as an ionic liquid. Arylation reactions of 2-phenyloxazoline proceed with concomitant oxazolidine cleavage to give 2-(N-acetylamino)ethyl benzoates promoted by side product CH3COOH. The dual-purpose ionic liquid medium is compatible with both ligandless Ru for di-arylation (optimal pre-catalyst: RuCl3·xH2O) and Ru-phosphane (optimal pre-catalyst: [RuCl2(p-cymene)]2/P(p-Tol)3 1:4) catalysts (1–5 mol-%) for selective mono-arylation.

MADS-box genes play a pivotal role in various processes, including floral and seed development, controlling flowering time, regulation of fruits ripening, and respond to abiotic and biotic stressors in planta. Tobacco (Nicotiana tabacum) has been widely used as a model plant for analyzing the gene function, however, there has been less information on the regulation of flowering, and the associated genes. In the present study, a total of 168 NtMADS-box genes were identified from tobacco, and their phylogenetic relationship, chromosome locations, and gene structures were further analyzed. NtMADS-box genes can be clustered into four sub-families of M&alpha, M&gamma, MIKC*, and MIKCC. A total of 111 NtMADS-box genes were distributed on 20 chromosomes, and 57 NtMADS-box genes were located on the unanchored scaffolds due to the complex and incomplete assembly of the tobacco genome. Expression profiles of NtMADS-box genes by microarray from 23 different tissues indicated that members in different NtMADS-box gene subfamilies might play specific roles in the growth and flower development, and the transcript levels of 24 NtMADS-box genes were confirmed by quantitative real-time PCR. Importantly, overexpressed NtSOC1/NtMADS133 could promote early flowering and dwarfism in transgenic tobacco plants. Therefore, our findings provide insights on the characterization of NtMADS-box genes to further study their functions in plant development.

Lithium metal is recognized as the “Holy Grail” of anode materials for high-energy-density batteries. However, the application of the lithium anode is seriously hindered due to its instability especially during the large-capacity lithium stripping/plating process. In this study, a dimensionally stable Li composite electrode is fabricated by electrodepositing lithium on Ag-modified Cu foam. The Li-Ag alloy formed during the initial plating shows micro-structural affinity to lithium and promotes the subsequent uniform Li stripping/plating on the Cu skeleton. The symmetric cell with Li/Ag-modified Cu composite electrode shows much-improved stability as compared to both the Li/3D Cu composite and Li plate electrodes. By investigating the electrochemical performance of the full cells with Li4Ti5O12 cathode, we find the interface stability of the Li composite electrode is deteriorated because of the increase of specific surface area. This work indicates that both dimensional and interface stabilities of lithium anodes are important for fabricating practical secondary lithium batteries.

Functionalized aryl chlorides are more economically attractive but usually much more difficult as substrates in metal-mediated couplings than the corresponding bromides and iodides. A catalyst prepared from a bulky (biaryl)diphenyl phosphane and a common ruthenium source (1:1) mediates selective direct monoarylations of arenes bearing 2-pyridyl and related ortho-directing groups in good yields. Sequential arylations to heterodiarylated products also proceed in satisfactory yields.

A novel palladium-catalyzed C-7 selective CH carbonylation of indolines with carbon monoxide for an expedient synthesis of pyrroloquinazolinediones, a structural motif with great potential in biologically active compounds, has been developed. Oxidation of the pyrroloquinazolinedione with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) could easily afford the corresponding indole-based derivative in excellent yield.

The 3D configuration of graphene materials has been intensively investigated due to their novel properties in biomedical, electrical and optical applications. But few reports have been intentionally carried out to understand the biological influence of 3D graphene materials so far. Herein, we presented an evaluation of the in vitro cytotoxicity of 3D graphene sheets fabricated by carbonization of polydopamine (PDA) films on a template of aligned nanopore arrays (NPAs) on a stainless steel surface. The prepared 3D graphene sheets with a thickness of ∼20 nm displayed a nanoporous architecture that can be readily tuned by the NPA template to control the morphology of the 3D configuration. The in vitro toxicity of the nanoporous 3D graphene sheets with pore sizes of ∼50 nm and ∼240 nm was evaluated using NIH-3T3 fibroblasts as the representative mammal fibroblast cell type. The NPA structure exhibits enhanced properties in cell attachment, spreading, proliferation, and the assembly of focal adhesions and actin filament associated proteins. Morphology-dependent cytotoxicity aroused by the 3D graphene configuration should be attributed to the engulfment of the carbon nanospheres embedded in the 3D configuration and the lack of both focal adhesions and actin filament associated proteins assembling at the nanoscale.

This study aims to investigate active phytochemicals isolated from Pyrola incarnata Fisch. (P. incarnata) and their protection against neuroinflammation induced by LPS. Betulin, accompanied with other 9 compounds, were isolated from P. incarnata and elucidated by spectroscopic analysis (1H-, 13C NMR). ELISA kits and the measurement of NO production based on Griess reaction showed that betulin (5) (250 μg/mL) could suppress LPS-induced activation of microglial cell BV-2 better than others by inhibiting inflammatory cytokines (TNF-α, IL-6, IL-1β) expression and NO production. With the guidance of computer-aided drug design and the analysis of biological experiment, we demonstrated betulin could reduce LPS-induced iNOS expression, prevent JNKs pathways, and down-regulate the phosphorylation levels of NF-κB/p65. In conclusion, betulin isolated from P. incarnata possessed outstanding anti-neuroinflammation potential, presumably related to iNOS expression, JNKs and NF-κB/p65 pathways. Therefore, Pyrola incarnata may be a valuable natural resource and betulin is a potential drug for the treatment of neurodegenerative disorders by inhibiting inflammatory mediators.

Lithium–sulfur battery is recognized as one of the most promising next-generation energy storage devices. However, the low specific capacity and inferior cycling stability of cathode are real bottlenecks in practical lithium–sulfur battery, owing to the low sulfur content and tap density of cathode with light-weight and nonpolar carbon host materials. In this study, conductive RuO2 stacking microspheres are designed and demonstrated as sulfur immobilizer for lithium–sulfur battery. The stacked RuO2 microspheres exhibit not only good conductive framework for both the transport of electrons and diffusion of electrolyte, but outstanding electrocatalytic activity for the conversion of lithium polysulfides. Moreover, the polarity of RuO2 is helpful to trap and confine soluble polysulfides during cycling. With a high tap density of 1.4 g cm−3 and high sulfur content of 81.8 wt%, the S/RuO2 composite delivers a high gravimetric and volumetric capacity of 985 mAh g−1-composite and 1360 mAh cm−3-composite at 0.2 C rate, respectively. Resulting from the fast redox kinetics, an excellent rate capability of 479 mAh g−1-composite can be also obtained at 5 C rate. Overall, this work unfolds a potential strategy to realize the combination of high energy density and improved cycling stability of lithium–sulfur battery.

The realisation of optically detected magnetic resonance via nitrogen vacancy centers in diamond faces challenges at high magnetic fields which include growing energy consumption of control pulses as well as decreasing sensitivities. Here we address these challenges with the design of shaped pulses in microwave control sequences that achieve orders magnitude reductions in energy consumption and concomitant increases in sensitivity when compared to standard top-hat microwave pulses. The method proposed here is general and can be applied to any quantum sensor subjected to pulsed control sequences., Comment: 7 pages, 4 figures

We show that arbitrary $N$-qubit interactions among nuclear spins can be achieved efficiently in solid state quantum platforms, such as nitrogen vacancy centers in diamond, by exerting control only on the electron spin coupled to the nuclei. This allows to exploit nuclear spins as robust quantum registers and the direct measurement of nuclear many-body correlators. The method takes advantage of recently introduced dynamical decoupling techniques and avoids the necessity of external, slow, control on the nuclei. Our protocol is general, being applicable to other nuclear spin-based platforms with electronic spin defects acting as mediators as silicon carbide.

We propose a quantum control scheme aimed at interacting systems that gives rise to highly selective coupling among their near-to-resonance constituents. Our protocol implements temporal control of the interaction strength, switching it on and off again adiabatically. This soft temporal modulation significantly suppresses off-resonant contributions in the interactions. Among the applications of our method we show that it allows us to perform an efficient rotating-wave approximation in a wide parameter regime, the elimination of side peaks in quantum sensing experiments, and selective high-fidelity entanglement gates on nuclear spins with close frequencies. We apply our theory to nitrogen-vacancy centers in diamond and demonstrate the possibility for the detection of weak electron-nuclear coupling under the presence of strong perturbations.

We propose a pulsed dynamical decoupling protocol as the generator of tunable, fast, and robust quantum phase gates between two microwave-driven trapped ion hyperfine qubits. The protocol consists of sequences of $\pi$-pulses acting on ions that are oriented along an externally applied magnetic field gradient. In contrast to existing approaches, in our design the two vibrational modes of the ion chain cooperate under the influence of the external microwave driving to achieve significantly increased gate speeds. Our scheme is robust against the dominant noise sources, which are errors on the magnetic field and microwave pulse intensities, as well as motional heating, predicting two-qubit gates with fidelities above $99.9\%$ in tens of microseconds., Comment: 11 pages + Supplemental Material, (6 + 1 figures)

The nitrogen-vacancy (N-V) color center in diamond is an enormously important platform for the development of quantum sensors, including for single-spin and single-molecule NMR. Detection of weak single-spin signals is greatly enhanced by repeated sequences of microwave pulses; in these dynamicaldecoupling techniques, the key control parameters swept in the experiment are the time intervals, τ, between pulses. Here, we show that, in fact, the pulse duration tp offers a powerful additional control parameter. While a non-negligible tp was previously considered simply a source of experimental error, we elucidate here the underlying quantum dynamics: we identify a landscape of quantum-state crossings which are usually inactive (closed) but may be controllably activated (opened) by adjusting tp from zero. We identify these crossings with recently observed but unexpected dips (so-called spurious dips) seen in the quantum coherence of the N-V spin. With this new understanding, both the position and the strength of these sharp features may be accurately controlled; they coexist with the usual broader coherence dips of short-duration microwave pulses, but their sharpness allows for higher-resolution spectroscopy with quantum diamond sensors, or their analogs.

A hybrid quantum register consisting of nuclear spins in a solid-state platform coupled to a central electron spin is expected to combine the advantages of its elements. However, the potential to exploit long nuclear spin coherence times is severely limited by magnetic noise from the central electron spin during external interrogation. We overcome this obstacle and present protocols for addressing a decoherence-free nuclear spin subspace, which was not accessible by previously existing methods. We demonstrate the efficacy of our protocols using detailed numerical simulations of a nitrogen-vacancy centre with nearby $^{13}$C nuclei, and show that the resulting hybrid quantum register is immune to electron spin noise and external magnetic field drifts. Our work takes an important step toward realizing robust quantum registers that can be easily manipulated, entangled, and, at the same time, well isolated from external noise, with applications from quantum information processing and communication to quantum sensing., Comment: Revised version with more materials

We present a method to identify spurious signals generated by finite-width pulses in quantum sensing experiments and apply it to recently proposed dynamical decoupling sequences for accurate spectral interpretation. We first study the origin of these fake resonances and quantify their behavior in a situation that involves the measurement of a classical magnetic field. Here we show that a change of the initial phase of the sensor or, equivalently, of the decoupling pulses leads to oscillations in the spurious signal intensity while the real resonances remain intact. Finally we extend our results to the quantum regime for the unambiguous detection of remote nuclear spins by utilization of a nitrogen vacancy sensor in diamond., Comment: 8 pages, 5 figures

We decompose the quantum adiabatic evolution as the products of gauge invariant unitary operators and obtain the exact nonadiabatic correction in the adiabatic approximation. A necessary and sufficient condition that leads to adiabatic evolution with geometric phases is provided, and we determine that in the adiabatic evolution, while the eigenstates are slowly varying, the eigenenergies and degeneracy of the Hamiltonian can change rapidly. We exemplify this result by the example of the adiabatic evolution driven by parametrized pulse sequences. For driving fields that are rotating slowly with the same average energy and evolution path, fast modulation fields can have smaller nonadiabatic errors than obtained under the traditional approach with a constant amplitude.

We propose a method to measure the hyperfine vectors between a nitrogen-vacancy (NV) center and an environment of interacting nuclear spins. Our protocol enables the generation of tunable electron-nuclear coupling Hamiltonians while suppressing unwanted inter-nuclear interactions. In this manner, each nucleus can be addressed and controlled individually thereby permitting the reconstruction of the individual hyperfine vectors. With this ability the 3D-structure of spin ensembles and spins in bio-molecules can be identified without the necessity of varying the direction of applied magnetic fields. We demonstrate examples including the complete reconstruction of an interacting spin cluster in diamond and 3D imaging of all the nuclear spins in a bio-molecule.

Methods to selectively detect and manipulate nuclear spins by single electrons of solid-state defects play a central role for quantum information processing and nanoscale nuclear magnetic resonance (NMR). However, with standard techniques, no more than eight nuclear spins have been resolved by a single defect centre. Here we develop a method that improves significantly the ability to detect, address and manipulate nuclear spins unambiguously and individually in a broad frequency band by using a nitrogen-vacancy (NV) centre as model system. On the basis of delayed entanglement control, a technique combining microwave and radio frequency fields, our method allows to selectively perform robust high-fidelity entangling gates between hardly resolved nuclear spins and the NV electron. Long-lived qubit memories can be naturally incorporated to our method for improved performance. The application of our ideas will increase the number of useful register qubits accessible to a defect centre and improve the signal of nanoscale NMR., Single electrons of solid-state defects can be used to detect nearby nuclear spins, but so far only a few at a time have been resolved. Here the authors propose an approach based on delayed entanglement echo that demonstrates improved detection and manipulation capabilities of nuclear spins by an NV centre.

Melatonin reportedly increases abiotic and biotic stress tolerance in plants, but information on its in vivo effects during postharvest physiological deterioration (PPD) in cassava is limited. In this study, we investigated the effect of melatonin in regulating cassava PPD. Treatment with 500 mg/L melatonin significantly delayed cassava PPD and reduced the accumulation of hydrogen peroxide (H2O2) while increasing the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR), but not ascorbate peroxidase (APX). Transcript analysis further showed that expression of copper/zinc SOD (MeCu/ZnSOD), MeCAT1, glutathione peroxidase (MeGPX), peroxidase 3 (MePX3), and glutathione S-transferases (MeGST) was higher in cassava roots sliced treated with 500 mg/L melatonin than in those not exposed to exogenous melatonin. These data demonstrate that melatonin delays cassava PPD by directly or indirectly maintaining homoeostasis of cellular reactive oxygen species (ROS). We also found that accumulation of endogenous melatonin and the transcript levels of melatonin biosynthesis genes changed dynamically during the PPD process. This finding suggested that endogenous melatonin acts as a signal modulator for maintaining cassava PPD progression and that manipulation of melatonin biosynthesis genes through genetic engineering might prevent cassava root deterioration.

Selective control of qubits in a quantum register for the purposes of quantum information processing represents a critical challenge for dense spin ensembles in solid state systems. Here we present a protocol that achieves a complete set of selective single and two-qubit gates on nuclear spins in such an ensemble in diamond facilitated by a nearby NV center. The protocol suppresses internuclear interactions as well as unwanted coupling between the NV center and other spins of the ensemble to achieve quantum gate fidelities well exceeding 99% . Notably, our method can be applied to weakly coupled, distant, spins and therefore represents a scalable procedure that exploits the exceptional properties of nuclear spins in diamond as robust quantum memories., 5 pages + Supplemental Material, (2 + 2 figures)

The quantum ratchet effect means that the directed transport emerges in a quantum system without a net force. The delta-kicked model is a quantum Hamiltonian model for the quantum ratchet effect. This paper investigates the quantum ratchet effect based on a time non-uniform double-kicked model, in which two flashing potentials alternately act on a particle with a homogeneous initial state of zero momentum, while the intervals between adjacent actions are not equal. The evolution equation of the state of the particle is derived from its Schrödinger equation, and the numerical method to solve the evolution equation is pointed out. The results show that quantum resonances can induce the ratchet effect in this time non-uniform double-kicked model under certain conditions; some quantum resonances, which cannot induce the ratchet effect in previous models, can induce the ratchet effect in this model, and the strengths of the ratchet effect in this model are stronger than those in previous models under certain conditions. These results enrich people’s understanding of the delta-kicked model, and provides a new optional scheme to control the quantum transport of cold atoms in experiment.

Salinity is an abiotic stress that substantially limits crop production worldwide. To identify salt stress tolerance determinants, we screened for Arabidopsis mutants that are hypersensitive to salt stress and designated these mutants as short root in salt medium (rsa). One of these mutants, rsa3-1, is hypersensitive to NaCl and LiCl but not to CsCl or to general osmotic stress. Reactive oxygen species (ROS) over-accumulate in rsa3-1 plants under salt stress. Gene expression profiling with Affymetrix microarray analysis revealed that RSA3 controls expression of many genes including genes encoding proteins for ROS detoxification under salt stress. Map-based cloning showed that RSA3 encodes a xyloglucan galactosyltransferase, which is allelic to a gene previously named MUR3/KAM1. The RSA3/MUR3/KAM1-encoded xylogluscan galactosyltransferase regulates actin microfilament organization (and thereby contributes to endomembrane distribution) and is also involved in cell wall biosynthesis. In rsa3-1, actin cannot assemble and form bundles as it does in the wild-type but instead aggregates in the cytoplasm. Furthermore, addition of phalloidin, which prevents actin depolymerization, can rescue salt hypersensitivity of rsa3-1. Together, these results suggest that RSA3/MUR3/KAM1 along with other cell wall-associated proteins plays a critical role in salt stress tolerance by maintaining the proper organization of actin microfilaments in order to minimize damage caused by excessive ROS.