Electric-Field-Induced Chirality in Columnar Liquid Crystals.

We describe a novel class of tetraphenylbenzene-based discotic molecules with exceptional self-assembling properties. Absorption and fluorescence studies confirmed the formation of J-type aggregates in solution. The discotic mesogens also show an enhancement of the emission upon aggregation. Interestingly, these discotic molecules displayed enantiotropic hexagonal columnar liquid crystal (LC) phases that can be switched into a helical columnar organization by application of an electric field. The helical columns arise from the electric-field-induced tilt of the polar fluorobenzene ring that directs all of the peripheral phenyl groups into a propeller-like conformation with respect to the central benzene core. A cooperative assembly process of these propeller-shaped molecules resolves into a helical columnar organization, in which the preferred helical sense is obtained from the stereogenic center proximate to the polar carbon-fluorine bond. The ease of inducing chirality in columnar LCs by an electric field presents opportunities to create next-generation chiral materials for a variety of applications.

Metallocalix[4]arene Polymers for Gravimetric Detection of N-Nitrosodialkylamines.

N-Nitrosamines are found in food, drugs, air, water, and soil. They pose a significant risk to human health because of their carcinogenicity; consequently, materials that can be used to selectively and sensitively detect nitrosamines are needed. In this work, we designed and synthesized two polymers bearing calix[4]arene or 4-tert-butylcalix[4]arene tungsten-imido complexes (PCalixH and PCalixtBu) as N-nitrosodimethylamine (NDMA) receptors. The interaction between metallocalix[4]arene monomers/polymers and NDMA was confirmed by 1H NMR and IR spectroscopy. Single-crystal X-ray analysis further revealed that the host-guest interaction is based on binding of the terminal oxygen of NDMA to tungsten within the calixarene cavity. Gravimetric detection of NDMA was performed on a quartz crystal microbalance (QCM) in air. Both polymers show responses to NDMA, with PCalixtBu exhibiting a low theoretical limit of detection of 5 ppb for NDMA. The sensor also shows high selectivity toward NDMA and moderate humidity tolerance. This work provides a sensitive sensor for detection of NDMA and also offers a class of new, selective, and efficient NDMA receptors for the future design of NDMA sensors and NDMA extraction materials.

Achieving High-Quality Freshwater from a Self-Sustainable Integrated Solar Redox-Flow Desalination Device.

Solar-assisted electrochemical desalination has offered a new energy-water nexus technology for sustainable development in recent studies. However, only a few reports have demonstrated insufficient photocurrent, a low salt removal rate, and poor stability. In this study, a high-quality freshwater level of 5-10 ppm (from an initial feed of 10 000 ppm), an enhanced salt removal rate (217.8 µg cm-2 min-1 of NaCl), and improved cycling and long-term stability are achieved by integrating dye-sensitized solar cells (DSSCs) and redox-flow desalination (RFD) under light irradiation without additional electrical energy consumption. The DSSC redox electrolyte (I- /I3- ) is circulated between the photoanode (N719/TiO2 ) and intermediate electrode (graphite paper). Two DSSCs in parallel or series connections are directly coupled to the RFD device. Overall, this hybrid system can be used to boost photo electrochemical desalination technology. The energy-water nexus technology will open a new route for dual-role devices with photodesalination functions without energy consumption and solar-to-electricity generation.

3d Transition-Metal-Mediated Columbite Nanocatalysts for Decentralized Electrosynthesis of Hydrogen Peroxide.

Decentralized electrosynthesis of hydrogen peroxide (H2 O2 ) via oxygen reduction reaction (ORR) can enable applications in disinfection control, pulping and textile bleaching, wastewater treatment, and renewable energy storage. Transition metal oxides are usually not efficient catalysts because they are more selective to produce H2 O. Here, it is shown that divalent 3d transition metal cations (Mn, Fe, Co, Ni, and Cu) can control the catalytic activity and selectivity of columbite nanoparticles. They are synthesized using polyoxoniobate (K7 HNb6 O19 ·13H2 O) and divalent metal cations by a hydrothermal method. The optimal NiNb2 O6 holds an H2 O2 selectivity of 96% with the corresponding H2 O2 Faradaic efficiency of 92% in a wide potential window from 0.2 to 0.6 V in alkaline electrolyte, superior to other transition metal oxide catalysts. Ex situ X-ray photoelectron and operando Fourier-transformed infrared spectroscopic studies, together with density functional theory calculations, reveal that 3d transition metals shift the d-band center of catalytically active surface Nb atoms and change their interactions with ORR intermediates. In an application demonstration, NiNb2 O6 delivers H2 O2 productivity up to 1 molH2O2 gcat -1 h-1 in an H-shaped electrolyzer and can yield catholytes containing 300 × 10-3 m H2 O2 to efficiently decomposing several organic dyes. The low-cost 3d transition-metal-mediated columbite catalysts show excellent application potentials.

Structure Recovery and Recycling of Used LiCoO2 Cathode Material.

A large number of lithium batteries have been retiring from the market of energy storage. Thus, recycling of the used electrode materials is becoming urgent. In this study, an industrial machinery processing was used to recover the crystal structure of the waste LiCoO2 materials with the combination of small-scale equipment repair technology. The results show that the crystal parameters of the repaired LiCoO2 material become small, the unit cell volume is reduced, and the crystal structure tends to be stable. The Co-O bond length of 1.9134 nm, O-Co-O bond angle of 94.72°, the (003) interplanar spacing of 0.467 nm indicate the excellent recovery level of the repaired LiCoO2 . In addition, the electrochemical performance of the repaired LiCoO2 material is greatly improved, compared with the waste material. The capacity of the repaired electrode material can be maintained at 120 mAh g-1 after 100 cycles at the current density of 0.2C. The promising rate performance of the repaired electrode material demonstrates the stable structure. This research work provides a large-scale method for the direct recovery of LiCoO2 with the reduction of unnecessary energy and reagent consumption, which will be beneficial to the environmental protection.

Cyclopentadienone Derivative Dimers as Tunable Photoswitches.

A series of photoswitchable cyclopentadienone derivative dimers bearing bromo, thienyl, 4-(dimethylamino)phenyl, 3-pyridinyl, 4-nitrophenyl and cyano groups was designed and facilely synthesized. Photoswitching properties such as the photoconversions in the photostationary state (PSS), the thermal kinetics and thermal half-lives of photoisomers were systematically investigated. These photoswitches show high fatigue resistance and large photoconversions in the PSS. This work proves that the photoswitching properties of photoswitches based on cyclopentadienone dimers can be tuned by substitution groups and also pave the way to functionalize the cyclopentadienone derivative dimer-based photoswitch, which is important for its future applications.

Azulene-Pyridine-Fused Heteroaromatics.

Azulene, a nonbenzenoid bicyclic aromatic hydrocarbon with unique electronic structure, is a promising building block for constructing nonbenzenoid π-conjugated systems. However, azulene-fused (hetero)aromatics remain rare as a result of limited synthetic methods. We report herein the unexpected synthesis of azulene- and pyridine-fused heteroaromatics Az-Py-1, a seven fused ring system with 30π electrons, by reductive cyclization of a 1-nitroazulene. The structure of Az-Py-1 was unambiguously confirmed by single-crystal X-ray analysis, and analogues Az-Py-2-Az-Py-6 were also synthesized, demonstrating that this is an effective method for constructing azulene- and pyridine-fused heteroaromatics. Theoretical calculations and photophysical and electrochemical studies of Az-Py-1-Az-Py-6 suggest their potential as semiconductors, and the single-crystal ribbons of Az-Py-1 show high hole mobilities up to 0.29 cm2 V-1 s-1.

Triindolo-Truxene Derivatives: Design, Synthesis, and Fine-Tuning of Electronic Properties and Molecular Assembly through Molecular Engineering.

Triindolo-truxene, a C3 -symmetric molecule with a large π-conjugated plane, has six methylene carbon atoms and three aromatic carbon atoms that can be facilely functionalized. Herein, butyl, carbonyl, cyano, and/or malononitrile groups were introduced at six methylene carbon atoms (6-, 14-, 22- or 8-, 16-, 24-positions) and/or three aromatic carbon atoms (2-, 10-, and 18-positions) of triindolo-truxene to produce eight derivatives. Their photophysical properties, electrochemical properties, and molecular assembly can be effectively modulated by substituents and substitution patterns. Incorporation of electron-deficient groups led to redshifts in both the absorption and emission of these derivatives and also lowered their HOMO and LUMO levels. Different substitution patterns resulted in the different intramolecular donor-acceptor interactions. Electron-deficient substituents at the methylene carbon atoms in the 6-, 14-, and 22-positions led to intramolecular charge transfer from the fluorene arms to the truxene core, whereas the corresponding substitutions at the methylene carbon atoms in the 8-, 16-, and 24-positions resulted in intramolecular charge transfer from the truxene core to the fluorene arms. The molecular packing in single crystals and molecular aggregation in solution are also influenced by the substituents and substitution patterns. This work provides a straightforward strategy to alter the properties of triindolo-truxene.

Stable Diindeno-Fused Corannulene Regioisomers with Open-Shell Singlet Ground States and Large Diradical Characters.

The synthesis of open-shell polycyclic hydrocarbons with large diradical characters is challenging because of their high reactivities. Herein, two diindeno-fused corannulene regioisomers DIC-1 and DIC-2, curved fragments of fullerene C104 , were synthesized that exhibit open-shell singlet ground states. The incorporation of the curved and non-alternant corannulene moiety within diradical systems leads to significant diradical characters as high as 0.98 for DIC-1 and 0.89 for DIC-2. Such high diradical characters can presumably be ascribed to the re-aromatization of the corannulene π system. Although the DIC compounds have large diradical characters, they display excellent stability under ambient conditions. The half-lives are 37 days for DIC-1 and 6.6 days for DIC-2 in solution. This work offers a new design strategy towards diradicaloids with large diradical characters yet maintain high stability.

Design and synthesis of hollow NiCo2O4 nanoboxes as anodes for lithium-ion and sodium-ion batteries.

Hollow porous NiCo2O4-nanoboxes (NCO-NBs) were synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystals as the template followed by a subsequent annealing treatment. The structure and morphology of the NCO-NBs were characterized using X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. When tested as potential anode materials for lithium-ion batteries, these porous NCO-NBs with a well-defined hollow structure manifested enhanced performance of Li storage. The discharge capacity of the NCO-NBs remained 1080 mA h g(-1) after 150 cycles at a current rate of 500 mA g(-1) and 884 mA h g(-1) could be obtained at a current density of 2000 mA g(-1) after 200 cycles. Even when cycled at a high density of 8000 mA g(-1), a comparable capacity of 630 mA h g(-1) could be achieved. Meanwhile, the Na storage behavior of NCO-NBs as anode materials of sodium ion batteries (SIBs) was initially investigated and they exhibited a high initial discharge capacity of 826 mA h g(-1), and a moderate capacity retention of 328 mA h g(-1) was retained after 30 cycles. The improved electrochemical performance for NCO-NBs could be attributed to the hierarchical hollow structure and the desirable composition, which provide enough space to alleviate volume expansion during the Li(+)/Na(+) insertion/extraction process and facilitate rapid transport of ions and electrons.

[Research progress of Gα(i/o)-coupled receptor-mediated supersensitization of adenylyl cyclase].

Persistent activation of most Gαi/o-coupled receptors resulted in enhanced activity of adenylyl cyclase (AC) and subsequent cyclic adenosine monophosphate (c AMP) accumulation within cells, and this phenomenon has generally been referred to as supersensitization of AC. It represents a cellular adaptive response that has been widely believed to be the cause of drug dependence. Supersensitization of AC might have an important impact during the processes of many central nervous system (CNS) disorder diseases, such as schizophrenia and depression, due to altered cell functions. This article provides an overview of the history and present status in our understanding of Gα(i/o)-coupled receptor-mediated supersensitization of AC, as well as discussion of the problems and future perspective.

Synthesis of anaerobic degradation biomarkers alkyl-, aryl- and cycloalkylsuccinic acids and their mass spectral characteristics.

Anaerobic biodegradation of petroleum hydrocarbons has been reported to proceed predominantly via fumarate addition to yield substituted succinate metabolites. These metabolites, commonly regarded as signature biomarkers, are specific indicators of anaero- bic hydrocarbon degradation by microbial activity. To the best of our knowledge, mass spectrometry information for 2-(1-methylalkylj succinic acids, 2-arylsuccinic acids, 2-cycloalkylsuccinic acids and/or their derivatives is still incomplete, especially for the analysis of environmental samples. Here, a novel approach is proposed for the successful synthesis of five hydrocarbon-derived succinic acids. The characteristic fragments of 2-[1-methylalkyllsuccinic acid diesters were investigated by four derivatization processes (methyl, ethyl, n-butyl and trimethylsilyl esterification], some of which are not available in official Libraries. Under electron ionization mass spec- trometry conditions, informative fragments of various molecular masses have been obtained. Results confirmed characteristic differ- ences among the derivatization processes of the chemically synthesized compounds. In the case of 2-[cyclo)alkylsuccinate esters, four intermediate fragments were observed at m/z 114 + 14n, 118 + 28n, [M - [17 + 14n1]]+ and [M - (59 + 14n)]+ (n = 1, 2 and 4 for methyl, ethyl and n-butyl ester]. However, for silylation the abundant fragment ions are at m/z 262, 217, 172, 147, 73 and [M - 15]+. These data provide information for the identification of hydrocarbon-derived succinic acids as anaerobic biodegradation intermediates in hydrocarbons- rich environments.

TRAIL suppresses tumor growth in mice by inducing tumor-infiltrating CD4(+)CD25 (+) Treg apoptosis.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a promising and novel anticancer cytokine, specifically kills numerous tumor cells by apoptosis. However, some malignancies are resistant to TRAIL treatment in clinical trials, thus limiting its therapeutic potential. In the present study, the TRAIL-resistant murine hepatocellular carcinoma cell line Hepa1-6 was used to elucidate the physiological significance of TRAIL resistance, especially with respect to the immune regulatory function of TRAIL. Hepa1-6 cells were resistant to TRAIL-induced apoptosis in vitro; however, intratumoral injection of recombinant soluble TRAIL inhibited tumor growth and prolonged survival time in tumor-bearing mice. Local TRAIL treatment decreased the number of intratumoral CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) but did not affect CD4(+)CD25(+)Foxp3(+) Tregs in the draining lymph nodes and spleen. Further investigation showed that TRAIL induced apoptosis of tumor-activated CD4(+)CD25(+)Foxp3(+) Tregs, but not of CD4(+)CD25(-) T cells. Moreover, mouse TRAIL receptor DR5 expression was detected on the surface of the tumor-infiltrating CD4(+)CD25(+)Foxp3(+) Tregs, but not on naïve CD4(+)CD25(+)Foxp3(+) Tregs. Interestingly, intratumoral injection of TRAIL not only decreased the number of CD4(+)CD25(+)Foxp3(+) Tregs but also increased the number of tumor-specific CD8(+) CTL and augmented their cytotoxicity to the tumor cells. These data provide the novel evidence for an immune regulatory function of TRAIL and may shed light on the clinical application of TRAIL.

Cyclophilin A (CyPA) induces chemotaxis independent of its peptidylprolyl cis-trans isomerase activity: direct binding between CyPA and the ectodomain of CD147.

Cyclophilin A (CyPA) is a ubiquitously distributed peptidylprolyl cis-trans isomerase (PPIase) that possesses diverse biological functions. Extracellular CyPA is a potent chemokine, which can directly induce leukocyte chemotaxis and contribute to the pathogenesis of inflammation-mediated diseases. Although it has been identified that the chemotaxis activity of CyPA is mediated through its cell surface signaling receptor CD147, the role of CyPA PPIase activity in this process is disputable, and the underlying molecular mechanism is still poorly understood. In this study, we present the first evidence that CyPA induces leukocyte chemotaxis through a direct binding with the ectodomain of CD147 (CD147(ECT)), independent of its PPIase activity. Although NMR study indicates that the CD147(ECT) binding site on CyPA overlaps with the PPIase active site, the PPIase inactive mutant CyPA(R55A) exhibits similar CD147(ECT) binding ability and chemotaxis activity to those of CyPA(WT). Furthermore, we have identified three key residues of CyPA involved in CD147(ECT) binding and found that mutations H70A, T107A, and R69A result in similar levels of reduction in CD147(ECT) binding ability and chemotaxis activity for CyPA, without affecting the PPIase activity. Our findings indicate that there exists a novel mechanism for CyPA to regulate cellular signaling processes, shedding new light on its applications in drug development and providing a new targeting site for drug design.

Promising oxonitridosilicate phosphor host Sr3Si2O4N2: synthesis, structure, and luminescence properties activated by Eu2+ and Ce3+/Li+ for pc-LEDs.

A novel oxonitridosilicate phosphor host Sr(3)Si(2)O(4)N(2) was synthesized in N(2)/H(2) (6%) atmosphere by solid state reaction at high temperature using SrCO(3), SiO(2), and Si(3)N(4) as starting materials. The crystal structure was determined by a Rietveld analysis on powder X-ray and neutron diffraction data. Sr(3)Si(2)O(4)N(2) crystallizes in cubic symmetry with space group Pa ̅3, Z = 24, and cell parameter a = 15.6593(1) Å. The structure of Sr(3)Si(2)O(4)N(2) is constructed by isolated and highly corrugated 12 rings which are composed of 12 vertex-sharing [SiO(2)N(2)] tetrahedra with bridging N and terminal O to form three-dimensional tunnels to accommodate the Sr(2+) ions. The calculated band structure shows that Sr(3)Si(2)O(4)N(2) is an indirect semiconductor with a band gap ≈ 2.84 eV, which is close to the experimental value ≈ 2.71 eV from linear extrapolation of the diffuse reflection spectrum. Sr(3-x)Si(2)O(4)N(2):xEu(2+) shows a typical emission band peaking at ~600 nm under 460 nm excitation, which perfectly matches the emission of blue InGaN light-emitting diodes. For Ce(3+)/Li(+)-codoped Sr(3)Si(2)O(4)N(2), one excitation band is in the UV range (280-350 nm) and the other in the UV blue range (380-420 nm), which matches emission of near-UV light-emitting diodes. Emission of Sr(3-2x)Si(2)O(4)N(2):xCe(3+),xLi(+) shows a asymmetric broad band peaking at ~520 nm. The long-wavelength excitation and emission of Eu(2+) and Ce(3+)/Li(+)-doped Sr(3)Si(2)O(4)N(2) make them attractive for applications in phosphor-converted white light-emitting diodes.

Improved hydrogen release from ammonia-borane with ZIF-8.

The promotion for hydrogen release from ammonia-borane (AB) was observed in the presence of ZIF-8. Even at concentrations of ZIF-8 as low as 0.25 mol %, a reduction of the onset temperature for dehydrogenation accompanies an increase in both the rate and amount of hydrogen released from AB.

Cryo-EM structures reveal the dynamic transformation of human alpha-2-macroglobulin working as a protease inhibitor.

Human alpha-2-macroglobulin is a well-known inhibitor of a broad spectrum of proteases and plays important roles in immunity, inflammation, and infections. Here, we report the cryo-EM structures of human alpha-2-macroglobulin in its native state, induced state transformed by its authentic substrate, human trypsin, and serial intermediate states between the native and fully induced states. These structures exhibit distinct conformations, which reveal the dynamic transformation of alpha-2-macro-globulin that acts as a protease inhibitor. The results shed light on the molecular mechanism of alpha-2-macroglobulin in entrapping substrates.

NASICON type KTi2(PO4)3 decorated by NTCDA-derived carbon layer for enhanced lithium/sodium storage.

NASICON type KTi2(PO4)3 decorated by NTCDA-derived carbon layer (KTP/NC) was prepared as anode material to obtain sustainable lithium/sodium ion storage (LIBs/SIBs). Due to its prominent capacitance, good electronic conductivity and ability to constrain volume, the KTP/NC composite realizes highly electrochemical kinetics both in LIBs and SIBs. For LIBs, the KTP/NC composite delivers a superior reversible capacity of 598.1 mAh g-1 after 200 cycles at 0.5C, impressive cyclability with 225.5 mAh g-1 after 3000 cycles at an ultrahigh current density of 26.1 C and conspicuous rate performance of 160.6 mAh g-1 even at 52.2 C. In addition, the composite has a wide operation-temperature window with favorable capacities of 147.1-372.9 mAh g-1 from -10 °C to 50 °C. As for SIBs, the KTP/NC composite maintains a stable discharge capacity of 112.5 mAh g-1 after 700 cycles at a current density of 2.6 C and conspicuous rate performance of 86.7 mAh g-1 at 5.2 C. The KTP/NC anode exhibits discharge capacities of 29.9-112.6 mAh g-1 from -10 °C to 40 °C. The results demonstrate that the KTP/NC composite would be a promising electrode material for LIBs and SIBs.

Porous Polymers Containing Metallocalix[4]arene for the Extraction of Tobacco-Specific Nitrosamines.

We designed porous polymers with a tungsten-calix[4]arene imido complex as the nitrosamine receptor for the efficient extraction of tobacco-specific nitrosamines (TSNAs) from water. The interaction between the metallocalix[4]arene and the TSNA, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nicotine-derived nitrosamine ketone, NNK) was investigated. We found that the incorporation of the nitrosamine receptor into porous polymers increased their selectivity toward NNK over nicotine. The polymer with an optimal ratio of calixarene-containing and porosity-inducing building blocks showed a high maximum adsorption capacity of up to 203 mg/g toward NNK under sonication, which was among the highest values reported. The adsorbed NNK could be removed from the polymer by soaking it in acetonitrile, enabling the adsorbent to be reused. A similar extraction efficiency to that under sonication could be achieved using the polymer-coated magnetic particles under stirring. We also proved that the material could efficiently extract TSNAs from real tobacco extract. This work not only provides an efficient material for the extraction of TSNAs but also offers a design strategy for efficient adsorbents.

An efficient method for refolding the extracellular portion of CD147 from the total bacterial lysate.

CD147 is a widely expressed transmembrane protein that mediates signal transduction, and it plays important roles in many physiological and pathological processes, such as tumor invasion and metastasis. The extracellular portion of CD147 (CD147(EC)) is responsible for its functional interactions with different signaling molecules. Due to the existence of two disulfide bonds, CD147(EC) is mainly expressed as an inclusion body in Escherichia coli. Here, we report a convenient rapid-dilution refolding protocol that enables the refolding of CD147(EC) efficiently from total bacterial lysate instead of pure inclusion bodies. Using this method, over 25 mg of CD147(EC) can be purified from 1 l of bacterial culture in M9 medium. The refolded CD147(EC) is well folded as characterized by nuclear magnetic resonance (NMR), and it can induce the expression of matrix metalloproteinase-9 in fibroblast cells. The described protocol is also applicable to the refolding of two immunoglobulin domains of CD147(EC) individually. Interestingly, we noticed that little protein was produced for the C-terminal immunoglobulin (Ig) domain of CD147(EC) by bacteria in M9 medium, even though it was overexpressed in Luria-Bertani (LB) medium. However, when the pH of the bacterial culture in M9 medium was adjusted in accordance with that in LB medium during growth, comparable expression level could be achieved.