Dual Differential Thermal Analysis and Instrument

INTRoDUCTlONAccordingtoRaoult'sLaw,thefreezingPOintdepressionJPD)ofasolutionisproPOrtionaltotheconcentrationofsolute.InthedetendnationoffreezingPOintJP),anicebathwasemployedusual1ytodecreasedthetemPerarereofthesolutionl'l,batitisnoteaSytocontro1.Wehaveovercomethisdrawharkbyusingsemiconductorchipl'],butthemeasurementoftemPeramrehasnotbeenimproved.Inthisresearch,theso1utionandpuresolventwereplacedtogetherinthesemiconductorcoolingbath,thernustorswereusedtoresPOnsethetemPeraturerrs,Tra…     

Study on Electrophotographic Properties for Dual Layered Photoreceptor

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Dual Activation of Aromatic Diels–Alder Reactions

The unusually fast Diels–Alder reactions of [5]cyclophanes were analyzed by DFT at the BLYP-D3(BJ)/TZ2P level of theory. The computations were guided by an integrated activation-strain and Kohn–Sham molecular orbital analysis. It is revealed why both [5]metacyclophane and [5]paracyclophane exhibit a significant rate enhancement compared to their planar benzene analogue. The activation strain analyses revealed that the enhanced reactivity originates from 1) predistortion of the aromatic core resulting in a reduced activation strain of the aromatic diene, and/or 2) enhanced interaction with the dienophile through a distortion-controlled lowering of the HOMO–LUMO gap within the diene. Both of these physical mechanisms and thus the rate of Diels–Alder cycloaddition can be tuned through different modes of geometrical distortion (meta versus para bridging) and by heteroatom substitution in the aromatic ring. Judicious choice of the bridge and heteroatom in the aromatic core enables effective tuning of the aromatic Diels–Alder reactivity to achieve activation barriers as low as 2 kcal mol⁻¹, which is an impressive 35 kcal mol⁻¹ lower than that of benzene.     

Synthesis and Characterization of Dual Acidic Ionic Liquids

Novel ionic liquids with dual acidity, of which the cation contains Brφnsted acidity and anions contain Lewis acidity were synthesized. These ionic liquids obtained were identified by NMR, FF-IR, SDT and FAB-MS. Their acidities were determined by pyridine probe on IR spectrography.     

Toughening Mechanism of Nanocomposite Physical Hydrogels Fabricated by a Single Gel Network with Dual Crosslinking——The Roles of the Dual Crosslinking Points

A facile method to fabricate tough and highly stretchable polyacrylamide (PAM) nanocomposite physical hydrogel (NCP gel) was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl hybrid silica nanoparticles (VSNPs) as the analogous covalent crosslinking points and the reversible hydrogen bonds among the PAM chains as the physical crosslinking points. In order to further elucidate the toughening mechanism of the PAM NCP gel, especially to understand the role of the dual crosslinking points, the PAM hybrid hydrogels (H gels) and a series of poly(acrylamide-co-dimethylacrylamide) (P(AM-co-DMAA)) NCP gels were designed and fabricated. Their mechanical properties were compared with those of the PAM NCP gels. The PAM H gels are prepared by simply mixing the PAM chains with bare silica nanoparticles (SNPs). Relative to the poor mechanical properties of the PAM H gel, the PAM NCP gel is remarkably tough and stretchable and also generates large number of micro-cracks to stop notch propagation, indicating the important role of PAM grafted VSNPs in toughening the NCP gel. In the P(AM-co-DMAA) NCP gels, the P(AM-co-DMAA) chains are grafted on VSNPs and the polydimethylacrylamide (PDMAA) only forms very weak hydrogen bonds between themselves. It is found that mechanical properties of the PAM NCP gel, such as the tensile strength and the elongation at break, are enhanced significantly, but those of the P(AM-co-DMAA) NCP gels decreased rapidly with decreasing AM content. This result reveals the role of the hydrogen bonds among the grafted polymer chains as the physical crosslinking points in toughening the NCP gel.     

Dual Brønsted acid/nucleophilic activation of carbonylimidazole derivatives

Carbonylimidazole derivatives have been found to be highly active acylation reagents for esterification and amidation in the presence of pyridinium salts. These reactions are thought to involve both Br?nsted acid and nucleophilic catalysis. This mode of activation has been applied to the synthesis of difficult to access oxazolidinones, as well as esters and amides. Finally, the use of pyridinium salts has been shown to accelerate the esterification of carboxylic acids with imidazole carbamates.     

Microscopic and Mesoscopic Dual Postsynthetic Modifications of Metal–Organic Frameworks

We report the dual postsynthetic modification (PSM) of a metal–organic framework (MOF) involving the microscopic conversion of C−H bonds into C−C bonds and the mesoscopic introduction of hierarchical porosity. MOF crystals underwent single-crystal-to-single-crystal transformations during the electrophilic aromatic substitution of Co₂(m-DOBDC) (m-DOBDC⁴⁻=4,6-dioxo-1,3-benzenedicarboxylate) with alkyl halides and formaldehyde. The steric hindrance caused by the proximity of the introduced functional groups to the coordination bonds reduced bond stability and facilitated the transformation into hierarchically porous mesostructures by etching with in situ generated protons (hydroniums) and halides. The numerous defect sites in the mesostructural MOFs are potential water-sorption sites. However, since the introduced functional groups are close to the main adsorption sites, even methyl groups are able to considerably decrease water adsorption, whereas hydroxy groups increase adsorption at low vapor pressures.     

Synchronous Dual Electrolyte Additive Sustains Zn Metal Anode with 5600 h Lifespan

Despite conspicuous merits of Zn metal anodes, the commercialization is still handicapped by rampant dendrite formation and notorious side reaction. Manipulating the nucleation mode and deposition orientation of Zn is a key to rendering stabilized Zn anodes. Here, a dual electrolyte additive strategy is put forward via the direct cooperation of xylitol (XY) and graphene oxide (GO) species into typical zinc sulfate electrolyte. As verified by molecular dynamics simulations, the incorporated XY molecules could regulate the solvation structure of Zn²⁺, thus inhibiting hydrogen evolution and side reactions. The self-assembled GO layer is in favor of facilitating the desolvation process to accelerate reaction kinetics. Progressive nucleation and orientational deposition can be realized under the synergistic modulation, enabling a dense and uniform Zn deposition. Consequently, symmetric cell based on dual additives harvests a highly reversible cycling of 5600 h at 1.0 mA cm⁻²/1.0 mAh cm⁻².     

Dual Fluorescent- and Isotopic-Labelled Self-Assembling Vancomycin for in vivo Imaging of Bacterial Infections

The increase of bacterial resistance demands rapid and accurate diagnosis of bacterial infections. Biosurface-induced supramolecular assembly for diagnosis and therapy has received little attention in detecting bacterial infections. Herein we present a dual fluorescent-nuclear probe based on self-assembly of vancomycin (Van) on Gram-positive bacteria for imaging bacterial infection. A Van- and rhodamine-modified peptide derivative (Rho-FF-Van), as the imaging agent, binds to the terminal peptide of the methicillin-resistant staphylococcus aureus (MRSA) and self-assembles to form nanoaggregates on the surface of MRSA. In an in vivo myositis model, Rho-FF-Van results in a significant increased fluorescence signal at the MRSA infected site. Radiolabeled with iodine-125, Rho-FF-Van shows strong radioactive signal in the MRSA-infected lungs in a murine model. This novel dual fluorescent and nuclear probe promises a new way for in vivo imaging of bacterial infections.     

Dual super-electrophilic and Diels–Alder reactivity of neutral 10π heteroaromatic substrates

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Polyisoprene Bearing Dual Functionalized Mini-blocky Chain-ends Prepared from Neodymium-mediated Coordinative Chain Transfer Polymerizations

Through neodymium-mediated coordinative chain transfer copolymerizaiton(CCTcoP), polyisoprenes bearing dual hydroxylated mini-blocky chain-ends were prepared via a three-step strategy. Kinetic studies revealed that, the polymerization demonstrated typical features of CCTcoP across the whole polymerization process, i.e., quasi-living polymerization characteristic, tunable molecular weights, narrow molecular weight distributions, and atom economies. Comparing to previously reported CCTP homopolyme...     

Dual fluorescence and electrochemical detection of the organophosphorus pesticides—Ethion,malathion and fenthion

Organophosphorus (OP) based pesticides are known powerful inhibitors of cholinesterases, thus the toxicity of this class of compounds causes serious environmental and human health concerns. We report that benzodipyrido[3,2-a:2′,3′-c]phenazine (BDPPZ) and 3,6-dimethylbenzodipyrido-[3,2-a:2′,3′-c]phenazine (DM-BDPPZ) provide independent fluorescent and electrochemical signal transductions in the presence of the organophosphorus (OP) pesticides; fenthion, malathion and ethion. The presence of the methyl groups at the 3 and 6 positions in DM-BDPPZ was found to significantly influence the sensor performance. The difference in the fluorescence and electrochemical signals produced by the interaction of the sensor compound with each of the OP pesticides provides a means for differentiating between the three pesticides. Detection limits of 10^?8 M, 10^?9 and 10^?12 M were obtained for fenthion, malathion and ethion, respectively. Due to the high sensitivity and ability to minimize false positives these new sensors will be useful for potential integration for future environmental use.     

Dual Behaviour of Maltosyl-β-Cyclodextrins: Investigation of Formation of Inclusion and Glucose-type Complexes

To clarify the complexation behaviour of the less studied maltosyl--cyclodextrin, its interactions with some characteristic guests such as phenolphthalein and p-nitrophenol have been studied. The results show that similar types of inclusion complexes are formed as in the case of the unsubstituted -cyclodextrin. In addition to the formation of inclusion complexes, maltosyl--cyclodextrins interact with other complexing reagents, like borate, vanadate or molybdate and the maltosyl substituent forms sugar-type complexes. The properties of these complexes are similar to those of glucose.     

Dual cure composites: Could body temperature offset the absence of light activation?

Journal of Thermal Analysis and Calorimetry - Dual cure composites contain both chemically and light-induced polymerization initiators, taking advantage of both processes; however, some...     

Alternately π-Stacked Systems Assisted by o-Carborane: Dual Excimer Emission and Color Modulation by Bcage-Methylation

Herein, we report the unique solid-state excimer emission of three types of acridine-tethered o-carboranes with variable degrees of methylation at the o-carborane unit. They all showed columnar packing structures based on dimer formation, and two types of π-overlapping motifs were alternately stacked. From the photoluminescence (PL) measurements on the crystalline samples, it was found that three types of luminescence bands can simultaneously appear: monomer emission, excimer emission from the moderately π-stacked intra-dimer unit, and excimer emission from the widely π-stacked inter-dimer unit. Consequently, the PL colors were drastically changed by the steric effect of the methyl groups, with a strong correlation found between the π-overlapping and excimer character. In addition, variable-temperature PL measurements revealed that these PL species should be in thermal equilibrium at room temperature, with the intensity ratios sensitive toward temperature changes.     

Temperature/Light Dual‐Responsive Inclusion Complexes of α‐Cyclodextrins and Azobenzene‐Containing Polymers

Three kinds of photoresponsive copolymers with azobenzene side chains were synthesized by radical polymerization of N‐4‐phenylazophenylacrylamide (PAPA) with N‐isopropylacrylamide (NIPAM), N,N‐diethylacrylamide (DEAM) or N,N‐dimethylacrylamide (DMAM) respectively. Their structures were characterized by FT‐IR, ¹H‐NMR and UV/Vis spectroscopy. Their reversible photoresponses were studied with or without α‐cyclodextrin (α‐CD), which showed that both the copolymers and their inclusion complexes with α‐CD underwent rapid photoisomerization. The lower critical solution temperature (LCST) of the copolymers and their inclusion complexes with α‐CD were investigated by cloud point measurement, which showed that the LCST of three kinds of copolymers increased largely after adding α‐CD. After UV irradiation on the solutions of copolymers and their inclusion complexes, the LCST of the copolymers increased slightly with the absence of α‐CD, while decreased largely with the presence of α‐CD. Furthermore, the LCST reverted to its originality after visible light irradiation. This change of LCST could be reversibly controlled by UV and visible light irradiation alternately. In particular, in the copolymer of PAPA and DMAM, the reversible water solubility of the inclusion complexes could be triggered by alternating UV and visible light irradiation.     

Discovery of a Dual Function Cytochrome P450 that Catalyzes Enyne Formation in Cyclohexanoid Terpenoid Biosynthesis

The 1,3-enyne moiety is commonly found in cyclohexanoid natural products produced by endophytic and plant pathogenic fungi. Asperpentyn ( 1 ) is a 1,3-enyne-containing cyclohexanoid terpenoid isolated from Aspergillus and Pestalotiopsis. The genetic basis and biochemical mechanism of 1,3-enyne biosynthesis in 1 , and other natural products containing this motif, has remained enigmatic despite their potential ecological roles. Identified here is the biosynthetic gene cluster and characterization of two crucial enzymes in the biosynthesis of 1 . A P450 monooxygenase that has a dual function, to first catalyze dehydrogenation of the prenyl chain to generate a cis-diene intermediate and then serve as an acetylenase to yield an alkyne moiety, and thus the 1,3-enyne, was discovered. A UbiA prenyltransferase was also characterized and it is unusual in that it favors transferring a five-carbon prenyl chain, rather than a polyprenyl chain, to a p-hydroxybenzoic acid acceptor.     

Synthesis of 4‐Arylpiperazine Derivatives of Moclobemide: Potential Antidepressants with a Dual Mode of Action

Abstract

We report here the synthesis of substituted 4‐chloro‐N‐[3‐oxo‐3‐(4‐aryl‐1‐piperazinyl)‐propyl] benzamides (5–9), as potential new antidepressants, incorporating in a single molecule structural moieties related to a dual pharmacological profile: MAO‐A inhibitor and 5‐HT_1A receptor affinity.     

Dual interfacial engineering for efficient Cs2AgBiBr6 based solar cells

The emerging lead-free halide double perovskite solar cells have attracted widespread attentions due to their long-term stability and non-toxicity, but suffer from the low device performance. One efficiencylimiting factor is the improper contacts between the halide double perovskite and anode/cathode electrodes. Here, we improve the efficiency and stability of the bismuth-halide double perovskite based solar cells by a synergistic interface design for both electron and hole transport layers(ETL/HTL). The results show that the modification of the TiO_2 ETL with a thin hydrophobic C60 layer and replacement of the lithium-doped small molecule HTL with an un-doped conjugated polymer lead to higher surface quality of perovskite film and better energy-level alignment at the contacts. As a result, the optimized device shows reduced trap density, suppressed charge recombination and enhanced charge extraction, leading to an increase of 69% in device efficiency. In addition, the device also exhibits superior stability in ambient environment, heat stress and light bias after interface optimization. This work provides an efficient strategy for the device optimization of the emerging lead-free perovskite solar cells.