9-anthracene Carboxylic Acid Research Articles

ZnS Shells Enhance Triplet Energy Transfer from CdSe Nanocrystals for Photon Upconversion

Triplet energy transfer (TET) from semiconductor nanocrystals (NCs) to molecules is one of the bottlenecks that limits the efficiency of photon upconversion. While an inorganic shell can enhance the photoluminescence quantum yields (PLQYs), the role of the shell with respect to TET is still not clear. In this work, CdS and ZnS shells with different shell thickness are grown on 2.9 nm diameter CdSe NCs, resulting in nanostructures here that have increased radiative rates compared to the core. TET from these NCs to bound 9-anthracene carboxylic acid is investigated with linear photon upconversion measurements, time-resolved photoluminescence lifetime, and transient absorption spectroscopy. The ZnS shell enhances the photon upconversion QYs 1.6 times from 5.7% to 9.3%, with a concurrent increase of TET efficiency from 6.68% to 12.9% and the net rate of TET from 4.97 × 108 s–1 to 6.67 × 1010 s–1. In contrast, TET is barely observed for CdSe/CdS core–shell NCs. Considering the changes in PLQYs and upconversion...

Binary and ternary co-crystals and molecular salts of 3,5-dinitrobenzoic acid: A many-faceted supramolecular reagent

The co-crystallization of 3,5-dinitrobenzoic acid (DNBA) to form binary and ternary complexes is reported. Binary complexes (DNBA) (flouranthene) (1), (DNBA) (9-bromoanthracene) (2), (DNBA) (9-methylanthracene) (3) and (DNBA) (9-anthroic acid) (4) are all sustained by charge-transfer interactions. By introducing three different pyridine complexes, the ternary complexes (DNBA) (flouranthene) (5-nitro-2-aminopyridine) (5), (DNBA) (9-anthracenecarboxylic acid)∙(3-bromo-2-aminopyridinium) (6) and (DNBA) (9-anthroic acid) (3-nitro-2-aminopyridine) (7) were synthesized utilizing an additional classical hydrogen bond from the DNBA to the pyridine. Compound 6 formed a molecular salt via proton exchange between the DNBA and 3-bromo-2-aminopyridine, whereas all other complexes are neutral (co-crystals).

Ca2 +-activated Cl− current is antiarrhythmic by reducing both spatial and temporal heterogeneity of cardiac repolarization

The role of Ca2+-activated Cl− current (ICl(Ca)) in cardiac arrhythmias is still controversial. It can generate delayed afterdepolarizations in Ca2+-overloaded cells while in other studies incidence of early afterdepolarization (EAD) was reduced by ICl(Ca). Therefore our goal was to examine the role of ICl(Ca) in spatial and temporal heterogeneity of cardiac repolarization and EAD formation.Experiments were performed on isolated canine cardiomyocytes originating from various regions of the left ventricle; subepicardial, midmyocardial and subendocardial cells, as well as apical and basal cells of the midmyocardium. ICl(Ca) was blocked by 0.5mmol/L 9-anthracene carboxylic acid (9-AC). Action potential (AP) changes were tested with sharp microelectrode recording. Whole-cell 9-AC-sensitive current was measured with either square pulse voltage-clamp or AP voltage-clamp (APVC). Protein expression of TMEM16A and Bestrophin-3, ion channel proteins mediating ICl(Ca), was detected by Western blot.9-AC reduced phase-1 repolarization in every tested cell. 9-AC also increased AP duration in a reverse rate-dependent manner in all cell types except for subepicardial cells. Neither ICl(Ca) density recorded with square pulses nor the normalized expressions of TMEM16A and Bestrophin-3 proteins differed significantly among the examined groups of cells. The early outward component of ICl(Ca) was significantly larger in subepicardial than in subendocardial cells in APVC setting. Applying a typical subepicardial AP as a command pulse resulted in a significantly larger early outward component in both subepicardial and subendocardial cells, compared to experiments when a typical subendocardial AP was applied.Inhibiting ICl(Ca) by 9-AC generated EADs at low stimulation rates and their incidence increased upon beta-adrenergic stimulation. 9-AC increased the short-term variability of repolarization also.We suggest a protective role for ICl(Ca) against risk of arrhythmias by reducing spatial and temporal heterogeneity of cardiac repolarization and EAD formation.

Crystal Structure of the 9-Anthracene–Carboxylic Acid Photochemical Dimer and Its Solvates by X-ray Diffraction and Raman Microscopy

The photodimerization of anthracene derivatives constitutes a model system for intermolecular [4 + 4] cycloadditions. In this paper we deal with the elusive 9-anthracene–carboxylic case and study the crystal state of the head-to-tail dimer, obtained by the reaction of the monomer in various solvents both in its unary and solvated forms, by X-ray diffraction and confocal Raman microscopy in the lattice phonon region. A number of solvates have been identified, and their structures have been solved and here presented. The 9-anthracene–carboxylic acid dimer appears to be an exemplary case of a molecular crystal easily prone to host solvent molecules in the interstices of the framework generated by homomolecular hydrogen bonds. Alternatively, the hydrogen bonds between solvent molecules and the carboxylic group may establish supramolecular structures of closely packed architectures. Raman microscopy has also allowed us to investigate the short-lived dimer, which is produced in the crystal-to-crystal photoreact...

Parametric Study for Dimeric Anthracene-Based Mechanophore-Embedded Thermoset Polymer Matrix Using Molecular Dynamics

ABSTRACTThis paper presents a parametric study to investigate the effect of relevant design variables on mechanochemical reaction and mechanical properties of a mechanophore-embedded thermoset polymer matrix. Mechanophores emit fluorescence when a specific covalent bond breaks due to external stress, and thus have attracted immense research interest as a damage sensor. Recently, a mechanophore named dimeric 9-anthracene carboxylic acid (Di-AC) was synthesized successfully and incorporated into epoxy-based thermoset polymer matrix to detect damage precursor. However, there is significant potential in modeling the complex mechanochemistry associated with the Di-AC to obtain a better understanding of this mechanophore and its interaction with the host thermoset material. In this study, a hybrid MD simulation methodology is employed to explore this complex mechanochemistry along with the investigation of the effect of design parameters on the mechanophore performance. The hybrid MD simulation method enables the simulation of Di-AC synthesis, epoxy curing, and mechanical loading test; therefore, the experimental process performed can be emulated accurately. Previously, the hybrid MD method showed the capability of capturing experimentally observed phenomena such as early signal detection and yield strength variation between neat epoxy system and epoxy with 5 wt% Di-AC thermoset polymer. In this paper, the effect of curing temperature on mechanophore activation and mechanical properties is investigated. A series of temperatures are used in the curing simulation, which are experimentally achievable. Results show that curing temperature below glass transition temperature maintains early signal detection and yield strength decreases when the curing temperature increases above the glass transition temperature. Good correlation is observed with experimental results.

Dimeric anthracene-based mechanophore for damage precursor detection in epoxy-based thermoset polymer matrix: Characterization and atomistic modeling

The mechanochemical response of a dimeric anthracene-based mechanophore (force-sensitive molecule), embedded within a thermoset polymer matrix, is studied through characterization and atomistic modeling. The dimeric anthracene-based mechanophore (dimeric 9-anthracene carboxylic acid, Di-AC) synthesized through ultraviolet dimerization was successfully incorporated into an epoxy-based thermoset polymer matrix to detect damage precursors. Mechanical loading tests showed that the Di-AC embedded epoxy polymer is capable of detecting damage precursors via fluorescence emission that occurs immediately before the yield point. The sensitivity of the Di-AC to external stress, which enables the damage precursor detection, is verified through a comparative study of bond dissociation energies of mechanophores using atomistic simulations. A hybrid molecular dynamics (MD) simulation methodology, integrating a classical force-field and a bond-order based force-field, is used to simulate epoxy curing, investigate elastic moduli and yield strength/strain, and capture mechanophore activation. Local work analysis within the hybrid MD simulation methodology is conducted to capture the critical strain representing the initiation of mechanophore activation due to the deformation of Di-AC embedded epoxy polymer. The capability to detect damage precursor is observed through MD simulations by comparing the yield strain and the critical strain. Furthermore, the experimentally observed variation in yield strength due to the inclusion of Di-AC is accurately reproduced by the comparative study between two systems: neat epoxy and 5wt% Di-AC epoxy polymer, thus, validating the computational framework.

Regioselective Molecularly Imprinted Reaction Field for [4 + 4] Photocyclodimerization of 2-Anthracenecarboxylic Acid.

Molecularly imprinted cavities have functioned as a regioselective reaction field for the [4 + 4] photocyclodimerization of 2-anthracenecarboxylic acid (2-AC). Molecularly imprinted polymers were prepared by precipitation polymerization of N-methacryloyl-4-aminobenzamidine as a functional monomer to form a complex with template 2-AC and ethylene glycol dimethacrylate as a crosslinking monomer. The 2-AC-imprinted cavities thus constructed preferentially bound 2-AC with an affinity greater than that toward structurally related 9-anthracenecarboxylic acid, 2-aminoanthracene, and unsubstituted anthracene. Moreover, from the four possible regioisomeric cyclodimers, they mediated the [4 + 4] photocyclodimerization of 2-AC specifically to the anti-head-to-tail (anti-HT) isomer. This indicates that the imprinted cavities accommodate two 2-AC molecules in an anti-HT manner, thereby facilitating the subsequent regioselective photocyclodimerization.

Calcium Activated Chloride Current in Mammalian Ventricular Myocytes

Background: Calcium activated Cl− current (ICl(Ca)) mediated by TMEM16A and/or Bestrophin-3 may contribute to cardiac arrhythmias. The true profile of ICl(Ca) during an actual ventricular action potential (AP), however, is poorly understood. Our goal was to study the current profile under normal calcium cycling and AP voltage-clamp condition as well as in case of altered intracellular calcium concentration ([Ca2+]i). The expression of TMEM16A and/or Bestrophin-3 in canine and human left ventricular myocytes was examined. The possible spatial distribution of these proteins and their co-localization with Cav1.2 was also studied.Methods: Whole-cell configuration of the patch-clamp technique and action potential voltage-clamp were used to monitor ICl(Ca), detected as 9-anthracene carboxylic acid (9-AC)-sensitive current. FURA-2-AM dye was used to measure [Ca2+]i. Expression and cellular localization of Cav1.2, Bestrophin-3 and TMEM16A was analyzed with immunocytochemistry and confocal microscopy.Results: Under AP voltage-clamp conditions the profile of ICl(Ca) contained an early fast outward (1.62±0.06 A/F) and a late inward component (−0.16±0.02 A/F), overlapping early and terminal repolarizations, respectively. Both components were reduced by ryanodine (1.05±0.03 A/F; −0.07±0.03 A/F), while fully abolished by BAPTA (0.13±0.10 A/F; −0.08±0.02 A/F), but not EGTA (1.17±0.09 A/F; −0.13±0.02 A/F). Setting [Ca2+]i to the systolic level (1.1 µM) decreased ICl(Ca), while application of Bay K8644, isoproterenol, and faster stimulation rates increased the amplitude of ICl(Ca). Both L-type Ca2+ current and ICl(Ca) were eliminated by nisoldipine. TMEM16A and Bestrophin-3 showed strong co-localization with one another and also with Cav1.2 channels both canine myocytes and human ventricular myocardium.Conclusions: Activation of ICl(Ca) in canine ventricular cells requires calcium entry through neighboring L-type Ca2+ channels and is only augmented by SR Ca2+-release. Substantial activation of ICl(Ca) requires high Ca2+ in the dyadic clefts which can be effectively buffered by BAPTA, but not EGTA.

Dual-emissive polystyrene@zeolitic imidazolate framework-8 composite for ratiometric detection of singlet oxygen.

This work demonstrated the potential of zeolitic imidazolate framework-8 (ZIF-8) as a host for the co-encapsulation of multiple fluorescent cargos to fabricate fluorescent composites for ratiometric sensing. The one-pot self-assembly of 2-methylimidazole, zinc nitrate, 9-anthracenecarboxylic acid (AnC), and polystyrene sphere doped with europium chelate (EuPS) in methanol solution can lead to the formation of dual-emissive EuPS@AnC/ZIF-8 with excellent fluorescent activity. Based on the distinct fluorescent responses of Eu3+ and AnC to singlet oxygen (1O2), EuPS@AnC/ZIF-8 can be developed as a ratiometric sensor for 1O2 detection. In this ratiometric sensor, Eu3+ fluorescence was employed as a reference signal for providing built-in correction to avoid environmental effects, while AnC fluorescence served as a response signal to detect 1O2 because of its turn-off behavior upon reacting with 1O2. Benefiting from the confinement effect of the ZIF-8 host, the presented sensor showed high sensitivity toward 1O2 with a detection limit of 43 nM and excellent selectivity over other reactive oxygen species. More attractively, the target responsive fluorescent color change of EuPS@AnC/ZIF-8 allowed 1O2 to be easily identified by the naked eye under a UV lamp. We hope that this study will provide a new insight into the design and application of multifunctional composites based on metal-organic frameworks.

Universal stress‐sensing dimeric anthracene‐based mechanophore particle fillers incorporated into polyurethane thermoset matrices

Mechanochemistry, in which mechanical forces induce chemical changes, can allow for targeted damage detection by way of embedded mechanophore units, which emit a measurable signal change correlating to an applied force. In this work, we successfully created stress-sensing, functional composites by employing microparticles of the mechanophore dimeric 9-anthracene carboxylic acid in a thermoset polyurethane matrix. The goal being to study the application of the particles as universal stress-sensing fillers in network polymer matrix composites, after previously evaluating the particles in an epoxy matrix. Under a compressive force, there is bond breakage in the mechanically weak cyclooctane photodimers, such that there is reversion to the fluorescent anthracene-type monomers. This fluorescent emission was then correlated to the applied strain, and the precursors to damage were detected with a noticeable signal change at a strain of only 2%, which was attributed to increased interactions between the matrix and the particles, with possible surface grafting occurring. This early damage detection was additionally possible at very low particle loadings of 2.5 and 5 wt%, with the 5 wt% loading showing enhanced material properties, due to particle reinforcement. Overall, the stress-sensitive particle filler allows for facile addition of advanced functionality to these ubiquitous thermoset composites. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Sonoelectrochemical Synthesis of Nano Zinc (II) Complexes with 9-Anthracenecarboxylic Acid: Effect of Current Density and Study of their Photophysical Properties.

A new zinc complex, [Zn (9-AC)2] (1) (9-AC=9-anthracenecarboxylic acid), was prepared via conventional electrochemical method in a fast and facile process and fully characterized by 1H NMR, 13C NMR, IR spectroscopy and elemental analysis. The nano structures of the same compound were successfully produced by a facile and environment-friendly sonoelectrochemical route at different current densities (0.5, 1.2, 1.8, 2.5 and 3.5mA/cm2). The new nano-structure particles were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analysis. Thermal stability of single crystal and nano-size samples of the prepared compound was studied by thermogravimetric and differential thermal analysis. The comparison of the effect of current density without and with ultrasonic irradiation on particle size has been investigated in convectional electrochemical and sonoelectrochemical method respectively. The results showed that using ultrasonic irradiation with increasing the current density lead to decrease the particle sizes unlike conventional electrochemical method. In other words, when the current density increase from 0.5 to 3.5mA/cm2, in sonoelectrochemical method, the particle sizes decrease from 100 to 48nm while, in convectional electrochemical method, the particle sizes increase from 400 to 1200nm and possible explanation offered. Photoluminescence properties of the nano-structured and crystalline bulk of the prepared complex at room temperature in the solid state have been investigated in detail. The results indicate that the size of the complex particles has an important effect on their optical properties.

Syntheses, structures, surface photovoltage and luminescent properties of a novel lead(II) coordination polymer containing anthracene chromophore

A novel 1D lead(II) coordination polymer containing anthracene chromophore through the employment of hydrothermal techniques by using 9-anthracenecarboxylic acid and PbI2, [Pb(9-aca)2(H2O)2] (1) (9-acaH=9-anthracenecarboxylic acid) has been synthesized and structurally characterized by X-ray single-crystal diffraction as well as by powder X-ray diffraction and elemental analysis. In compound 1, each PbO8 polyhedron is linked to each other by oxygen atoms from 9-acaH ligand to form a 1D molecular nanowire with a diameter of 1.22 nm. Surface photovoltage spectroscopy (SPS) and field-induced surface photovoltage (FISPS) of compound 1 indicate that it possesses positive SPV response in the range of 300–800 nm and shows p-type semiconductor characteristic. Luminescent properties of compound 1 reveal that the compound exhibit strong luminescence, ascribed to the charge transfer of anthracene chromophore and the semiconductor 1D Pb2O2 chain.

Dynamics of Energy Transfer from CdSe Nanocrystals to Triplet States of Anthracene Ligand Molecules

The combination of CdSe semiconductor nanocrystals with 9-anthracene carboxylic acid ligands can sensitize triplet–triplet annihilation on the emitter molecule diphenylanthracene. This hybrid system has recently been shown to upconvert visible light (532 nm) to ultraviolet light (420 nm) (Huang, Z., et al. Nano Lett. 2015, 15, 5552–5557). In the current paper, time-resolved photoluminescence measurements are used to characterize the kinetics of the energy transfer from the CdSe exciton state to the triplet state of the anthracene ligand. We find that 9-anthracene carboxylic acid binds to CdSe according to Poisson statistics with a maximum number of 2–3 ligands per nanocrystal. The CdSe-to-ligand energy transfer rate is 1.5 × 107 s–1. The overall efficiency of the energy transfer appears to be limited by the presence of fast nonradiative decay channels in the nanocrystals and the low coverage of anthracene ligands, resulting from the specific ligand exchange conditions used in this paper. Possible strategi...

The chloride-channel blocker 9-anthracenecarboxylic acid reduces the nonlinear capacitance of prestin-associated charge movement.

The basis of the extraordinary sensitivity and frequency selectivity of the cochlea is a chloride‐sensitive protein called prestin which can produce an electromechanical response and which resides in the basolateral plasma membrane of outer hair cells (OHCs). The compound 9‐anthracenecarboxylic acid (9‐AC), an inhibitor of chloride channels, has been found to reduce the electromechanical response of the cochlea and the OHC mechanical impedance. To elucidate these 9‐AC effects, the functional electromechanical status of prestin was assayed by measuring the nonlinear capacitance of OHCs from the guinea‐pig cochlea and of prestin‐transfected human embryonic kidney 293 (HEK 293) cells. Extracellular application of 9‐AC caused reversible, dose‐dependent and chloride‐sensitive reduction in OHC nonlinear charge transfer, Q max. Prestin‐transfected cells also showed reversible reduction in Q max. For OHCs, intracellular 9‐AC application as well as reduced intracellular pH had no detectable effect on the reduction in Q max by extracellularly applied 9‐AC. In the prestin‐transfected cells, cytosolic application of 9‐AC approximately halved the blocking efficacy of extracellularly applied 9‐AC. OHC inside‐out patches presented the whole‐cell blocking characteristics. Disruption of the cytoskeleton by preventing actin polymerization with latrunculin A or by decoupling of spectrin from actin with diamide did not affect the 9‐AC‐evoked reduction in Q max. We conclude that 9‐AC acts on the electromechanical transducer principally by interaction with prestin rather than acting via the cytoskeleton, chloride channels or pH. The 9‐AC block presents characteristics in common with salicylate, but is almost an order of magnitude faster. 9‐AC provides a new tool for elucidating the molecular dynamics of prestin function.

Dimeric anthracene-based mechanophore particles for damage precursor detection in reinforced epoxy matrix composites

The problem of catastrophic damage purveys in any material application, and minimizing its occurrence is paramount for general health and safety. We have successfully synthesized, characterized, and applied dimeric 9-anthracene carboxylic acid (Di-AC)-based mechanophore particles to form stress sensing epoxy matrix composites. As Di-AC had never been previously applied as a mechanophore and thermosets are rarely studied in mechanochemistry, this created an alternative avenue for study in the field. Under an applied stress, the cyclooctane-rings in the Di-AC particles reverted back to their fluorescent anthracene form, which linearly enhanced the overall fluorescence of the composite in response to the applied strain. The fluorescent signal further allowed for stress sensing in the elastic region of the stress–strain curve, which is considered to be a form of damage precursor detection. Overall, the incorporation of Di-AC to the epoxy matrix added much desired stress sensing and damage precursor detection capabilities with good retention of the material properties.

ATP Release via GAP Junction Hemichannels in Rat Atrial Myocytes under Shear Stress

We have previously shown that shear stress (∼16 dyn/cm2) induces longitudinal Ca2+ propagation wave with a 0.2- to 3-s delay in atrial myocytes through the activation of P2Y1 purinergic signaling, and that the shear-mediated wave generation is inhibited by the blockade of gap junction hemichannels (J Physiol 2015 http://dx.doi.org/10.1113/JP271016). In the present study, we further examined whether atrial cells release ATP via the gap junction hemichannels. ATP releases of cells were directly measured with 2-s intervals as chemiluminescence emitted (at 562 nm) during ATP-driven luciferin-luciferase reaction. Shear stress was applied to fields of cells in a laminar flow chamber attached to the flow regulator. ATP was released from atrial myocytes by the application of shear stress in the range of 1-16 dyn/cm2 in a strength-dependent manner. The shear-induced ATP release occurred transiently with a maximal release (∼1.3x10−16 moles/μm2) at about 2 s and 90% decay at 4-6 s after the shear application (∼16 dyn/cm2 for 10 s). Removal of external Ca2+ to enhance the activity of the gap junction hemichannels increased the shear-mediated ATP release to ∼320% of control. In cells pre-treated with carbenoxolone (50 μM for 10 min) or La3+ (2 mM for 5 min), the hemichannel blockers, ATP release by shear application was suppressed by ∼50% and ∼90%, respectively. The shear-induced ATP release was not affected by the pre-treatment of 50 μM Gd3+ (5 min) or 1 mM 9-anthracenecarboxylic acid (10 min), suggesting no role of maxi anion channel and Cl− channels in shear-induced ATP release in these myocytes. Our data suggest that shear stress induces ATP release through the gap junction hemichannels in atrial myocytes.

铝胁迫下胡枝子根尖胼胝质形成规律及影响因素

PDF HTML阅读 XML下载 导出引用 引用提醒 铝胁迫下胡枝子根尖胼胝质形成规律及影响因素 DOI: 10.5846/stxb201406091185 作者: 作者单位: 中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室,中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室,湖北理工学院环境科学与工程学院,中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 土壤与农业可持续发展国家重点实验室开放基金课题(0812201225);湖北省自然基金面上项目(2014CFC1089);湖北省矿区环境污染控制与修复重点实验室开放基金(2013104);湖北理工学院引进人才项目(10yjz04R);国家重点基础研究发展计划项目(973项目)(2014CB441000) Analysis of variations in and factors affecting callose formation in response to al stress in Lespedeza Root Tips Author: Affiliation: State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,College of Environmental Science and Engineering,Hubei Institute of Technology,Huangshi,State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用水培试验,研究了铝胁迫下两个胡枝子品种根尖产生胼胝质的变化规律及影响因素。结果表明,两个品种的根尖铝吸收量与胼胝质形成量呈正比例关系。品种间差异主要是在根尖0-0.5 cm处。敏感品种胼胝质形成量同铝吸收量的变化趋势相一致,而耐性品种则在铝处理6 h时出现一个高峰值后下降。去除铝胁迫后,耐性品种胼胝质形成量并不显著减少。与单独铝处理相比,阴离子通道抑制剂苯甲酰甲醛加铝处理对两个品种胼胝质形成无影响;尼氟灭酸加铝处理抑制敏感品种胼胝质的形成,对耐性品种无影响;蒽-9-羧酸加铝处理显著抑制两个品种的胼胝质形成。另外,抑制剂2-去氧-D-葡萄糖加铝共同处理与单独铝处理相比,敏感品种的胼胝质形成量显著降低,耐性品种无影响。甘露醇对两个品种胼胝质形成的影响无显著差别。镧处理下胼胝质的形成量是耐性品种显著高于敏感品种,铝、镧同时处理胼胝质的形成量最高。敏感品种胼胝质形成处理间无差别。总之,耐性品种在铝胁迫下胼胝质形成与有机酸分泌可能存在一定的协调关系;铝胁迫下胼胝质形成是敏感指标;在一定条件下,特别是有机酸分泌前胼胝质的形成可能具有一定抗性意义;铝诱导胼胝质的形成受多种外界因素(浓度、时间、有机酸分泌,渗透压等)的影响。 Abstract:Lespedeza speices can grow very well in infertile acidic soils as native pioneer plants. The reasons why such plants are well adapted to these soils might be due to a combination of mechanisms. Al toxicity is the primary factor limiting plant growth in acidic soils. Our previous results indicated that secretion of malate and citrate from roots was related to the high Al-resistance of Lespedeza. The objective of this study was to investigate the formation of callose under Al stress and its regulating factors in two Lespedeza species with different Al resistance, and attempted to explore the relative role of callose formation and organic acid exudation in Al toxicity or resistance of Lespedeza. The results showed that increased Al uptake was associated with increased callose formation in both Lespedeza species. The differences in Al tolerance between the two species were mainly expressed at the root apical 0-0.5 cm. Moreover, the callose formation was similar to root Al uptake for Al-sensitive species, but not for Al-tolerant species, of which callose formation peaked at 6 h of Al treatment and then decreased. Callose formation of the tolerant species was not obviously reduced following removal of Al from the culture. Furthermore, no obvious differences in callose formation were observed under treatment with PG (phenylglyoxal, anion-channel inhibitor) plus Al as compared to Al treatment alone in both species. NIF (niflumic acid, anion-channel inhibitor) plus Al treatment inhibited callose formation in the Al-sensitive species, but not in the Al-tolerant species. Callose formation was inhibited by A-9-C (9-anthracene carboxylic acid, anion-channel inhibitor) plus Al treatment in both species. Compared with Al treatment alone, DDG plus Al treatment caused a significant reduction in callose formation in the Al-sensitive species but not in the Al-tolerant species. No differences in callose formation were observed for both species following mannitol treatment. Callose formation in response to La treatment was significantly higher in the Al-tolerant species than in the Al-sensitive species and was still higher following treatment with both Al and La. However, no differences in callose formation in Al-sensitive species were detected among treatments. In summary, callose synthesis may be regulated in conjunction with organic acid exudation. Callose formation may be a sensitive indicator of Al stress and may also function in Al tolerance before organic acids are secreted from roots. Finally, callose formation may be dependent on many factors, including Al concentration, treatment time, organic acid exudation, and osmotic pressure. Further studies are required to examine these additional factors to determine the complex mechanisms mediating callose formation. 参考文献 相似文献 引证文献

Nanocrystal Size and Quantum Yield in the Upconversion of Green to Violet Light with CdSe and Anthracene Derivatives

We investigate the parameters affecting the upconversion of visible light in a hybrid organic–inorganic system based on CdSe nanocrystal (NC) sensitizers, 9-anthracene carboxylic acid (9-ACA) transmitter, and diphenylanthracene (DPA) annihilator. Seven wurtzite CdSe NCs ranging in photoluminescence quantum yield (PLQY) from 2.0% to 11%, and in diameter from 2.7 to 5.1 nm, were used in combination with the 9-ACA and DPA molecules. Using 2.7 nm diameter CdSe NCs, we show that the upconversion quantum yield has a quadratic to linear dependence on NC sensitizer concentration. Additionally, upconversion efficiency correlates positively with 9-ACA surface coverage on CdSe NCs and NC PLQY but negatively with particle size. This work clearly illustrates the path toward designing nanocrystal–molecule combinations with high upconversion efficiency that have potential applications in the fields of bioimaging, solar energy conversion, and data storage.

Photoinduced Crystallization in Ionic Liquids: Photodimerization-induced Equilibrium Shift and Crystal Patterning

Abstract An ionic liquid (IL) composed of 9-anthracenecarboxylate anion and ammonium cation possessing three diethylene glycol chains shows phototriggered dimerization of anthracence chromophores. It causes segregation and crystallization of protonated 9-anthracenecarboxylic acid dimer, which is associated with the concurrent liberation of the free amine in the IL. This work provides a new molecular design for photoresponsive ILs, whose first application for site-selective photopatterning is demonstrated.

Electrochemical performance of reduced graphene oxide surface-modified with 9-anthracene carboxylic acid

An efficient approach for the preparation of 9-anthracene carboxylic acid (ACA) modified reduced graphene oxide (rGO) was demonstrated in this study.