Intermediate Bridging Research Articles

Influence of Donor Skeleton on Intramolecular Electron Transfer Amount for Efficient Perovskite Solar Cells

AbstractThe passivation of the defects derived from rapid‐crystallization with electron‐donating molecules is always a prerequisite to obtain desirable perovskite films for efficient and stable solar cells, thus, the in‐depth understanding on the correlations between molecular structure and passivation capacity is of great importance for screening passivators. Here, we introduce the double‐ended amide molecule into perovskite precursor solution to modulate crystallization process and passivate defects. By regulating the intermediate bridging skeletons with alkyl, alkenyl and benzene groups, the results show the passivation strength highly depends on the spin‐state electronic structure that serves as an intrinsic descriptor to determine the intramolecular charge distribution by controlling orbital electron transfer from the donor segment to acceptor segment. Upon careful optimization, the benzene‐bridged amide molecule demonstrates superior efficacy on improving perovskite film quality. As a physical proof‐of‐concept, the carbon‐based, all‐inorganic CsPbI2Br solar cell delivers a significantly increased efficiency of 15.51 % with a remarkably improved stability. Based on the same principle, a champion efficiency of 24.20 % is further obtained on the inverted (Cs0.05MA0.05FA0.9)Pb(I0.93Br0.07)3 solar cell. These findings provide new fundamental insights into the influence of spin‐state modulation on effective perovskite solar cells.

Influence of Donor Skeleton on Intramolecular Electron Transfer Amount for Efficient Perovskite Solar Cells.

The passivation of the defects derived from rapid-crystallization with electron-donating molecules is always a prerequisite to obtain desirable perovskite films for efficient and stable solar cells, thus, the in-depth understanding on the correlations between molecular structure and passivation capacity is of great importance for screening passivators. Here, we introduce the double-ended amide molecule into perovskite precursor solution to modulate crystallization process and passivate defects. By regulating the intermediate bridging skeletons with alkyl, alkenyl and benzene groups, the results show the passivation strength highly depends on the spin-state electronic structure that serves as an intrinsic descriptor to determine the intramolecular charge distribution by controlling orbital electron transfer from the donor segment to acceptor segment. Upon careful optimization, the benzene-bridged amide molecule demonstrates superior efficacy on improving perovskite film quality. As a physical proof-of-concept, the carbon-based, all-inorganic CsPbI2Br solar cell delivers a significantly increased efficiency of 15.51 % with a remarkably improved stability. Based on the same principle, a champion efficiency of 24.20 % is further obtained on the inverted (Cs0.05MA0.05FA0.9)Pb(I0.93Br0.07)3 solar cell. These findings provide new fundamental insights into the influence of spin-state modulation on effective perovskite solar cells.

The Tibetan Plateau bridge: Influence of remote teleconnections from extratropical and tropical forcings on climate anomalies

Recent advances in the bridging roles played by the Tibetan Plateau (TP) are reviewed in terms of the remote influence of circulation anomalies over the North Atlantic Ocean on Asian monsoon and El Niño-Southern Oscillation (ENSO) events, and in a clear link between the tropical oceans and Asian climate anomalies. The authors firstly introduce how the winter and spring anomalies in the North Atlantic Ocean affect the seasonal transition over the South Asian monsoon region and subsequent ENSO events on the interannual timescale. A distinct negative sensible heating-baroclinic structure in May over the TP is found to provide an intermediate bridging effect in this Atlantic-Asian-Pacific connection. In summer, the North Atlantic Oscillation is significantly correlated with the variations of East China summer rainfall, and it is the TP's latent heating that plays the bridging role within. On the other hand, such a TP bridging effect also exists in the connection from the tropical oceans to extreme precipitation events over eastern China in summer, and from the midlatitude wave train to the biweekly oscillation of South China rainfall in spring.摘要本文回顾了青藏高原桥梁作用方面的最新研究进展, 涉及北大西洋气候异常对春, 夏亚洲季风和厄尔尼诺-南方涛动 (ENSO) 事件的遥相关影响, 热带海洋异常和中国东部极端气候异常之间的联系以及华南春雨的季节内变化等. 介绍了年际时间尺度上, 冬-春季北大西洋海表温度强迫如何影响南亚季风的季节性转变以及随后ENSO事件的触发. 5月份青藏高原上空显著的负感热斜压结构, 为北大西洋影响亚洲季风和ENSO提供了桥梁效应. 夏季北大西洋涛动与华东夏季降水变化显著相关, 高原潜热在这一关系中起着桥梁作用. 另一方面, 这种高原桥梁效应也存在于从热带海洋异常到东亚夏季极端降水事件的连接中, 以及从中纬度波列到华南春雨准双周振荡的联系中.

A hybrid quantum dot:MXene bulk heterojunction for an efficient infrared self-powered photodetector

A Br-MXene:PbS QD bulk heterostructure (BHJ) with an intermediate halogen bridging is developed to boost charge transfer at the donor/acceptor interface. The photodetector based on this BHJ exhibits an enhanced photoresponse performance.

Ultralow-loss fusion splicing between negative curvature hollow-core fibers and conventional SMFs with a reverse-tapering method.

Negative curvature hollow-core fibers (NC-HCFs) can boost the excellent performance of HCFs in terms of propagation loss, nonlinearity, and latency, while retaining large core and delicate cladding structures, which makes them distinctly different from conventional fibers. Construction of low-loss all-fiber NC-HCF architecture with conventional single-mode fibers (SMFs) is important for various applications. Here we demonstrate an efficient and reliable fusion splicing method to achieve low-loss connection between a NC-HCF and a conventional SMF. By controlling the mode-field profile of the SMF with a two-step reverse-tapering method, we realize a record-low insertion loss of 0.88 dB for a SMF/NC-HCF/SMF chain at 1310 nm. Our method is simple, effective, and reliable, compared with those methods that rely on intermediate bridging elements, such as graded-index fibers, and can greatly facilitate the integration of NC-HCFs and promote more advanced applications with such fibers.

Breaking Cassie's Law for Condensation in a Nanopatterned Slit.

We study the phase transitions of a fluid confined in a capillary slit made from two adjacent walls, each of which are a periodic composite of stripes of two different materials. For wide slits the capillary condensation occurs at a pressure which is described accurately by a combination of the Kelvin equation and the Cassie law for an averaged contact angle. However, for narrow slits the condensation occurs in two steps involving an intermediate bridging phase, with the corresponding pressures described by two new Kelvin equations. These are characterised by different contact angles due to interfacial pinning, with one larger and one smaller than the Cassie angle. We determine the triple point and predict two types of dispersion force induced Derjaguin-like corrections due to mesoscopic volume reduction and the singular free-energy contribution from nanodroplets and bubbles. We test these predictions using a fully microscopic density functional model which confirms their validity even for molecularly narrow slits. Analogous mesoscopic corrections are also predicted for two-dimensional systems arising from thermally induced interfacial wandering.

Design, synthesis, and evaluation of mono-carbonyl analogues of curcumin (MCACs) as potential antioxidants against periodontitis.

The application of curcumin is limited by its instability. Mono-carbonyl analogues of curcumin (MCACs) are structurally stable, yet the intermediate bridging ketones in their skeletons account for increased toxicity. This study aimed to synthesize and screen MCACs that exhibit low cytotoxicity and high antioxidant ability, and the effects of MCACs on experimental periodontitis were also investigated. The cytotoxicity of MCACs on MC3T3-E1 was determined by MTT assay. The antioxidant capacity was investigated by the cell viability against H2 O2 -induced damage and the level of reactive oxygen species (ROS) and malondialdehyde (MDA). The localization and protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was detected by immunofluorescence and western blot, respectively. In addition, MCAC was intragastrically administrated in rats with ligature-induced experimental periodontitis. The effects were assessed by bone resorption, as well as the immunohistology staining of inflammatory and oxidative stress markers. MCACs with cyclopentanone and containing pyrone showed lower toxicity than natural curcumin were synthesized (1A-10A, 1H-10H), among which, 1A exhibited the most potent cytoprotective effect against H2 O2 -induced damage. Such effects could be explained by the reduced MDA and ROS level, possibly through the nucleus translocation of Nrf2 and the induction of HO-1. Micro-CT results further indicated that 1A significantly reduced bone loss, along with an increased level of Nrf2 and HO-1, and decreased TNF-α and IL-1β. The present study has synthesized a novel antioxidant MCAC 1A with good biosafety and stability. MCAC 1A could serve as a host response modulator with preventive and protective effects on periodontitis.

Temperature-independent giant dielectric response in transitional BaTiO3 thin films

Ferroelectric materials exhibit the largest dielectric permittivities and piezoelectric responses in nature, making them invaluable in applications from supercapacitors or sensors to actuators or electromechanical transducers. The origin of this behavior is their proximity to phase transitions. However, the largest possible responses are most often not utilized due to the impracticality of using temperature as a control parameter and to operate at phase transitions. This has motivated the design of solid solutions with morphotropic phase boundaries between different polar phases that are tuned by composition and that are weakly dependent on temperature. Thus far, the best piezoelectrics have been achieved in materials with intermediate (bridging or adaptive) phases. But so far, complex chemistry or an intricate microstructure has been required to achieve temperature-independent phase-transition boundaries. Here, we report such a temperature-independent bridging state in thin films of chemically simple BaTiO3. A coexistence among tetragonal, orthorhombic, and their bridging low-symmetry phases are shown to induce continuous vertical polarization rotation, which recreates a smear in-transition state and leads to a giant temperature-independent dielectric response. The current material contains a ferroelectric state that is distinct from those at morphotropic phase boundaries and cannot be considered as ferroelectric crystals. We believe that other materials can be engineered in a similar way to contain a ferroelectric state with gradual change of structure, forming a class of transitional ferroelectrics. Similar mechanisms could be utilized in other materials to design low-power ferroelectrics, piezoelectrics, dielectrics, or shape-memory alloys, as well as efficient electro- and magnetocalorics.

Deoxygenation of nitrosoarene by N-heterocyclic carbene (NHC): an elusive Breslow-type intermediate bridging carbene and nitrene.

N-Heterocyclic carbene (NHC) activates and deoxygenates nitrosoarene (ArNO) to afford arylnitrene (ArN), thereby portraying a fundamental route connecting two 6e- species. A combination of spectroscopic and computational studies suggests that the interaction of ArNO with NHC affords a transient 2,2'-diamino imine-N-oxide as a key intermediate in ArNO deoxygenation.

Synthesis of melamine-formaldehyde microcapsules containing oil-based fragrances via intermediate polyacrylate bridging layers

Abstract A general and versatile strategy to prepare melamine-formaldehyde (MF) microcapsules encapsulating oil-based fragrances by combining solvent evaporation and in situ polymerization was proposed in this work. The oil-based fragrance was pre-encapsulated by an inner polyacrylate membrane via solvent evaporation, followed by in situ polymerization of MF precondensates as an outer shell. The polyacrylate membrane is used as an intermediate bridging layer to stabilize the oil-based fragrance, and to provide driving forces for in situ polymerization of MF precondensates through electrostatic attractions between carboxyl groups and ammonium ions. It was demonstrated that MF microcapsules containing clove oil were prepared successfully. The amount and the composition of the intermediate polyacrylate bridging layer were critical. Smooth and sphere-shaped MF-clove oil microcapsules were prepared when the weight ratio of polyacrylate to clove oil was over 60 wt% and the concentration of acrylic acid (AA) increased to 10 wt% in polyacrylate. In addition, MF microcapsules containing sunflower oil and hexyl salicylate were prepared by using this method. The work suggests that this new approach can be potentially used to encapsulate various core materials, tuning the shell properties of microcapsules such as thickness, mechanical strength and release properties.

Electrospun regenerated cellulose nanofiber based metal-chelating affinity membranes for protein adsorption

Abstract Fabricating metal-chelating affinity materials with excellent protein adsorption and isolation properties is of great significance in numerous biotechnological fields, yet still face huge challenges. Herein, we successfully developed a new kind of nanofiber based metal-chelating affinity membranes by orderly modifying the electrospun regenerated cellulose nanofibrous membranes (RC NFMs) with intermediate bridging agent of cyanuric chloride (CC), chelating agent of iminodiacetic acid (IDA) and affinity ligand of Fe3+ ions. The resultant Fe3+ ions immobilized RC NFMs (RC-CC-IDA-Fe3+ NFMs) exhibited a high lysozyme adsorption amount of 365 mg g-1 within the fast equilibrium adsorption time of 4 hours. Meanwhile, the performance of RC-CC-IDA-Fe3+ NFMs could be facilely regulated by controlling the properties and concentration of protein solutions. Moreover, the obtained nanofibrous affinity materials also possessed superior cycle performance and excellent regeneration ability. Undoubtedly, the successful fabrication of efficient RC-CC-IDA-Fe3+ NFMs might provide a new kind of affinity adsorbent for protein purification and other potential biotechnological fields.

地域に根ざした大学生の国際的志向性促進を 図る英語教材と指導法の開発課題 : 「教室型」と「海外研修型」の中間枠組みの提起

地域に根ざした大学生の国際的志向性促進を 図る英語教材と指導法の開発課題 : 「教室型」と「海外研修型」の中間枠組みの提起

Regulation of a distinct activated RIPK1 intermediate bridging complex I and complex II in TNFα-mediated apoptosis

Stimulation of cells with TNFα can promote distinct cell death pathways, including RIPK1-independent apoptosis, necroptosis, and RIPK1-dependent apoptosis (RDA)-the latter of which we still know little about. Here we show that RDA involves the rapid formation of a distinct detergent-insoluble, highly ubiquitinated, and activated RIPK1 pool, termed "iuRIPK1." iuRIPK1 forms after RIPK1 activation in TNF-receptor-associated complex I, and before cytosolic complex II formation and caspase activation. To identify regulators of iuRIPK1 formation and RIPK1 activation in RDA, we conducted a targeted siRNA screen of 1,288 genes. We found that NEK1, whose loss-of-function mutations have been identified in 3% of ALS patients, binds to activated RIPK1 and restricts RDA by negatively regulating formation of iuRIPK1, while LRRK2, a kinase implicated in Parkinson's disease, promotes RIPK1 activation and association with complex I in RDA. Further, the E3 ligases APC11 and c-Cbl promote RDA, and c-Cbl is recruited to complex I in RDA, where it promotes prodeath K63-ubiquitination of RIPK1 to lead to iuRIPK1 formation. Finally, we show that two different modes of necroptosis induction by TNFα exist which are differentially regulated by iuRIPK1 formation. Overall, this work reveals a distinct mechanism of RIPK1 activation that mediates the signaling mechanism of RDA as well as a type of necroptosis.

Skin layer in cyclic loading-cleaning of a nanofiber filter in filtering nano-aerosols.

Nano-aerosols from viruses to virgin pollutant particulates from combustion, 100nm or smaller, are harmful to our health as they penetrate readily into our body causing various diseases. Nanofiber filter can capture effectively these nano-aerosols. However, over time the pressure drop increases dramatically and cleaning of the filter by backpulse/backblow is essential for filter reuse. The cyclic loading-and-cleaning of a nanofiber filter has been investigated for the first time experimentally and theoretically. The "skin" layer, a thin region upstream of the nanofiber filter, plays a pivoting role in controlling the pressure drop excursion of the filter. We model the skin layer to be made up of numerous fine capillaries and examine how continuous aerosols deposited in the capillaries affect rapid rise in pressure drop followed by bridging of aerosols across the capillary openings leading to more bridging and ultimately formation of cake on top of the bridges and filter surface. We have been able to describe the deposition of aerosols in the capillary pores for depth filtration, the deposition of aerosols in the cake (surface filtration), and the intermediate bridging regime between these two. We can depict the complete pressure drop excursion including the S-shaped curve behavior from depth filtration transiting to surface filtration for a filter with severe skin effect. Our prediction matches extremely well with the 6 cycles of loading/cleaning on a 280-nm nanofiber filter subject to challenging nano-aerosols, 50-400nm. During cyclic loading and cleaning, the porosity and permeability in the skin layer for our experiment drop to 68% and 11-21% of their original values, respectively, and the effective pore diameter also drops from 1.2 to 0.6μm.

New Perspectives on Quinol Binding Motifs at the bc1 Complex Based on MD Simulations

The bc1 complex is a central player in the conversion of energy into ATP synthesis in photosynthesis and respiration, and its overall mechanism, the Q-cycle, is well known. However, the quinol-protein interaction that initiates Q-cycle at the Qo-binding site have not yet been described. Employing classical MD simulations in tandem with DFT calculations, the quinol binding motifs to the Qo-site of bc1 complex is investigated for a range of Qo-site protonation states. The computations revealed a novel configuration of the key side groups at the Qo-site site, such as H156, Y147 and E295, that stabilize the reaction complex and provide an optimal configuration prior to the charge transfer reactions between quinol and iron-sulfur cluster of the Rieske protein. Re-arrangements in the E295 and Y147 side chains were observed in all our simulations, showing intermediate bridging hydrogen bonding between quinol and E295, not observed before. Simulations were extended to study cytochrome c2 docking to cytochrome c1, required for the removal of electrons from the bc1 complex. We found, the docking interface is characterized by a semicircular arrangement of electrostatic residues that draws the cytochrome c2 and bc1 complex into an encounter complex, a hydrophobic minimal core to facilitate electron transfer, and mobility mismatch between the bound surfaces to induce post-electron transfer undocking.

Phase transitions and antiferroelectricity inBiFeO3from atomic-level simulations

The structural and polar properties of $\mathrm{BiFe}{\mathrm{O}}_{3}$ at finite temperature are investigated using an atomistic shell model fitted to first-principles calculations. Molecular dynamics simulations show a direct transition from the low-temperature $R3c$ ferroelectric phase to the Pbnm orthorhombic phase without evidence of any intermediate bridging phase between them. The high-temperature phase is characterized by the presence of two sublattices with opposite polarizations, and it displays the characteristic double-hysteresis loop under the action of an external electric field. The microscopic analysis reveals that the change in the polar direction and the large lattice strains observed during the antiferroelectric-ferroelectric phase transition originate from the interplay between polarization, oxygen octahedron rotations, and strain. As a result, the induced ferroelectric phase recovers the symmetry of the low-temperature $R3c$ phase.

THE GALACTIC CENSUS OF HIGH- AND MEDIUM-MASS PROTOSTARS. II. LUMINOSITIES AND EVOLUTIONARY STATES OF A COMPLETE SAMPLE OF DENSE GAS CLUMPS

(Abridged) The Census of High- and Medium-mass Protostars (CHaMP) is the first large-scale (280 degree<l<300 degree, -4 degree<b<2 degree), unbiased, sub-parsec resolution survey of Galactic molecular clumps and their embedded stars. Barnes et al. (2011) presented the source catalog of ~300 clumps based on HCO+(1-0) emission, used to estimate masses M. Here we use archival mid-infrared to mm continuum data to construct spectral energy distributions. Fitting two-temperature grey-body models, we derive bolometric luminosities, L. We find the clumps have 10Lsun<L<1E6.5Lsun and 0.1<L/M<1E3, consistent with theoretical expectations of a clump population that spans a range of instantaneous star formation efficiencies from 0 to ~50%. We thus expect L/M to be a useful, strongly-varying indicator of clump evolution during the star cluster formation process. We find correlations of the ratio of warm to cold component fluxes and of cold component temperature with L/M. We also find a near linear relation between L/M and Spitzer-IRAC specific intensity (surface brightness), which may thus also be useful as a star formation efficiency indicator. The lower bound of the clump $L/M$ distribution suggests the star formation efficiency per free-fall time is epsilon<0.2. We do not find strong correlations of L/M with mass surface density, velocity dispersion or virial parameter. We find a linear relation between L and L_{HCO+(1-0}}, although with large scatter for any given individual clump. Fitting together with extragalactic systems, the linear relation still holds, extending over 10 orders of magnitude in luminosity. The complete nature of the CHaMP survey over a several kiloparsec-scale region allows us to derive a measurement at an intermediate scale bridging those of individual clumps and whole galaxies.

Flood risk assessment for informal settlements

The urban informal settlements are particularly vulnerable to flooding events, due to both their generally poor quality of construction and high population density. An integrated approach to the analysis of flooding risk of informal settlements should take into account, and propagate, the many sources of uncertainty affecting the problem, ranging from the characterization of rainfall curve and flooding hazard to the characterization of the vulnerability of the portfolio of buildings. This paper proposes a probabilistic and modular approach for calculating the flooding risk in terms of the mean annual frequency of exceeding a specific limit state for each building within the informal settlement and the expected number of people affected (if the area is not evacuated). The flooding risk in this approach is calculated by the convolution of flooding hazard and flooding fragility for a specified limit state for each structure within the portfolio of buildings. This is achieved by employing the flooding height as an intermediate variable bridging over the fragility and hazard calculations. The focus of this paper is on an ultimate limit state where the life of slum dwellers is endangered by flooding. The fragility is calculated by using a logic tree procedure where several possible combinations of building features/construction details, and their eventual outcome in terms of the necessity to perform structural analysis or the application of nominal threshold flood heights, are taken into account. The logic tree branch probabilities are characterized based on both the orthophoto recognition and the sample in situ building survey. The application of the methodology is presented for Suna, a sub-ward of Dar es Salaam City (Tanzania) in the Msimbazi River basin having a high concentration of informal settlements.

Origin of high piezoelectric response in A-site disordered morphotropic phase boundary composition of lead-free piezoelectric 0.93(Na0.5Bi0.5)TiO3–0.07BaTiO3

Perovskite piezoelectric compositions near the morphotropic phase boundary (MPB) are known to exhibit high piezoelectric response. In lead-based ABO3 compound with B-site disorder, the origin of this enhancement has been associated with the presence of an intermediate monoclinic/orthorhombic state that bridges the adjacent ferroelectric rhombohedral and tetragonal phases. However, the origin of high piezoelectric response in lead-free ABO3 compounds with A-site disorder has not been conclusively established. We describe a microscopic model derived from comparative analyses of high resolution transmission electron microscopy and neutron diffraction that explains the origin of high piezoelectric response in lead-free MPB compositions of 0.93(Na0.5Bi0.5)TiO3–0.07BaTiO3. Direct observation of nanotwins with monoclinic symmetry confirmed the presence of an intermediate bridging phase that facilitates a pathway for polarization reorientation. Monoclinic distortions of an average rhombohedral phase are attributed to localized displacements of atoms along the non-polar directions.

A Minimally Invasive Treatment for Lumbar Disc Herniation: DiscoGel® Chemonucleolysis in Patients Unresponsive to Chemonucleolysis with Oxygen-Ozone

A multitude of therapies is available to treat disc herniation, ranging from conservative methods (medication and physical therapy) to minimally invasive (percutaneous) treatments and surgery. O₂-O₃ chemonucleolysis (O₂-O₃ therapy) is one of the minimally invasive treatments with the best cost/benefit ratio and lowest complication rate. Another substance recently made available exploiting the chemical properties of pure ethanol is DiscoGel®, a radiopaque gelified ethanol more viscous than absolute alcohol 8,9. The present study aimed to assess the therapeutic outcome of DiscoGel® chemonucleolysis in patients with lumbar disc herniation unresponsive to O₂-O₃ therapy. Thirty-two patients aged between 20 and 79 years were treated by DiscoGel® chemonucleolysis between December 2008 and January 2010. The treatment was successful (improvement in pain) in 24 out of 32 patients. DiscoGel® is safe and easy to handle and there were no complications related to product diffusivity outside the treatment site. The therapeutic success rate of DiscoGel® chemonucleolysis in patients unresponsive to O₂-O₃ therapy was satisfactory. Among other methods used to treat lumbar disc herniation, DiscoGel® chemonucleolysis can be deemed an intermediate procedure bridging conservative medical treatments and surgery.