Pure organic room-temperature phosphorescent (RTP) materials have been suggested to be promising bioimaging materials due to their good biocompatibility and long emission lifetime. Herein, we report ...a class of RTP materials. These materials are developed through the simple introduction of an aromatic carbonyl to a tetraphenylpyrrole molecule and also exhibit aggregation-induced emission (AIE) properties. These molecules show non-emission in solution and purely phosphorescent emission in the aggregated state, which are desirable properties for biological imaging. Highly crystalline nanoparticles can be easily fabricated with a long emission lifetime (20 μs), which eliminate background fluorescence interference from cells and tissues. The prepared nanoparticles demonstrate two-photon absorption characteristics and can be excited by near infrared (NIR) light, making them promising materials for deep-tissue optical imaging. This integrated aggregation-induced phosphorescence (AIP) strategy diversifies the existing pool of bioimaging agents to inspire the development of bioprobes in the future.
Organometal halide perovskites are inexpensive materials with desirable characteristics of color-tunable and narrow-band emissions for lighting and display technology, but they suffer from low ...photoluminescence quantum yields at low excitation fluencies. Here we developed a ligand-assisted reprecipitation strategy to fabricate brightly luminescent and color-tunable colloidal CH3NH3PbX3 (X = Br, I, Cl) quantum dots with absolute quantum yield up to 70% at room temperature and low excitation fluencies. To illustrate the photoluminescence enhancements in these quantum dots, we conducted comprehensive composition and surface characterizations and determined the time- and temperature-dependent photoluminescence spectra. Comparisons between small-sized CH3NH3PbBr3 quantum dots (average diameter 3.3 nm) and corresponding micrometer-sized bulk particles (2–8 μm) suggest that the intense increased photoluminescence quantum yield originates from the increase of exciton binding energy due to size reduction as well as proper chemical passivations of the Br-rich surface. We further demonstrated wide-color gamut white-light-emitting diodes using green emissive CH3NH3PbBr3 quantum dots and red emissive K2SiF6:Mn4+ as color converters, providing enhanced color quality for display technology. Moreover, colloidal CH3NH3PbX3 quantum dots are expected to exhibit interesting nanoscale excitonic properties and also have other potential applications in lasers, electroluminescence devices, and optical sensors.
The main objective of this paper is to study the effect of design and operating parameters, mainly reactor geometry, equivalence ratio and biomass feeding rate, on the performance of the gasification ...process of biomass in a three air stage continuous fixed bed downdraft reactor. The gasification of corn straw was carried out in the gasifier under atmospheric pressure, using air as gasifying agent. The results demonstrated that due to the three stage of air supply, a high and uniform temperature was achieved in the oxidation and reduction zones for better tar cracking. The designing of both the air supply system and rotating grate avoided bridging and channeling. The gas composition and tar yield were affected by the parameters including equivalence ratio (ER) and biomass feeding rate. When biomass feeding rate was 7.5 kg/h and ER was 0.25–0.27, the product gas of the gasifier attained a good condition with lower heating value (LHV) about 5400 kJ/m3 and cold gas efficiency about 65%. An increase in equivalence ratio led to higher temperature which in turn resulted in lower tar yield which was only 0.52 g/Nm3 at ER = 0.32. Increasing biomass feeding rate led to higher biomass consumption rate and process temperature. However, excessively high feeding rate was unbeneficial for biomass gasification cracking and reforming reactions, which led to a decrease in H2 and CO concentrations and an increase in tar yield. When ER was 0.27, with an increase of biomass feeding rate from 5.8 kg/h to 9.3 kg/h, the lower heating value decreased from 5455.5 kJ/Nm3 to 5253.2 kJ/Nm3 and tar yield increased from 0.82 g/Nm3 to 2.78 g/Nm3.
•An innovative gasifier with three air stage was designed to realize uniform air distribution.•The LHV and cold gas efficiency attained a good condition when ER was 0.25–0.27.•The tar yield as low as 0.5 g/Nm3 was achieved by increasing ER.•Temperature and tar yield were improved as the increase of feeding rate.
► Thermal decomposition characteristics of corn straw and rice husk. ► Characteristic parameters of TG–DTG curves of the samples are calculated. ► Variation of activation energy corresponding to ...different conversion fractions. ► Variation of reaction order corresponding to varied heating temperatures.
The study concerns the pyrolysis kinetics of agricultural wastes, corn straw (CS) and rice husk (RH). Thermogravimetric experiments were carried out in a thermogravimetric analyzer under inert conditions, and operated at different heating rates ranging from 5 to 40K/min. As the increment of heating rates, the variations of characteristic parameters from the TG–DTG curves were determined. Iso-conversional Starink approach and Avrami theory were used to evaluate the kinetic parameters, including apparent activation energy and reaction order. For the range of conversion fraction investigated (20–80%), the apparent activation energy of CS initially increased from 98.715 to 148.062kJ/mol and then decreased to 144.387kJ/mol afterwards, whilst the apparent activation energy of RH increased gradually from 50.492 to 88.994kJ/mol. With varied temperatures (517–697K), the corresponding value of reaction order was increased from 0.288 and 0.359 to 0.441 and 0.692, along with a decrease to 0.306 and 0.445, respectively.
Herein we report three metal–organic frameworks (MOFs), TABD-MOF-1, -2, and -3, constructed from Mg2+, Ni2+, and Co2+, respectively, and deprotonated ...4,4′-((Z,Z)-1,4-diphenylbuta-1,3-diene-1,4-diyl)dibenzoic acid (TABD-COOH). The fluorescence of these three MOFs is tuned from highly emissive to completely nonemissive via ligand-to-metal charge transfer by rational alteration of the metal ion. Through competitive coordination substitution, the organic linkers in the TABD-MOFs are released and subsequently reassemble to form emissive aggregates due to aggregation-induced emission. This enables highly sensitive and selective detection of explosives such as five-membered-ring energetic heterocyclic compounds in a few seconds with low detection limits through emission shift and/or turn-on. Remarkably, the cobalt-based MOF can selectively sense the powerful explosive 5-nitro-2,4-dihydro-3H-1,2,4-triazole-3-one with high sensitivity discernible by the naked eye (detection limit = 6.5 ng on a 1 cm2 testing strip) and parts per billion-scale sensitivity by spectroscopy via pronounced fluorescence emission.
Organic materials with long‐lived, color‐tunable phosphorescence are potentially useful for optical recording, anti‐counterfeiting, and bioimaging. Herein, we develop a series of novel host–guest ...organic phosphors allowing dynamic color tuning from the cyan (502 nm) to orange red (608 nm). Guest materials are employed to tune the phosphorescent color, while the host materials interact with the guest to activate the phosphorescence emission. These organic phosphors have an ultra‐long lifetime of 0.7 s and a maximum phosphorescence efficiency of 18.2 %. Although color‐tunable inks have already been developed using visible dyes, solution‐processed security inks that are temperature dependent and display time‐resolved printed images are unprecedented. This strategy can provide a crucial step towards the next‐generation of security technologies for information handling.
Multicolor swap shop: A facile doping approach for color‐tunable organic phosphorescence materials is enabled through hosts that not only restrict the molecular motion and avoid the triplet quenching from the oxygen, but also interact with the guests for the realization of phosphorescence. Color tunable, temperature dependent, and time‐resolved anti‐counterfeiting techniques are achieved by the printable and writable materials.
•Hydrothermal liquefaction (HTL) of microalgae C. pyrenoidosa and S. platensis.•Characterization of bio-crude oils and aqueous fractions during HTL process.•General reaction network for HTL of C. ...pyrenoidosa and S. platensis.•Specific reaction pathways for HTL of lipid, protein and non-fibrous carbohydrate.
Low-lipid microalgae can be successfully converted to bio-crude oil in a hydrothermal liquefaction (HTL) environment. This study examined the behavior of hydrothermal liquefaction of two low-lipid content microalgae in subcritical water between 200°C and 320°C at 20°C intervals. Under these conditions, the chemical composition and functional groups for the bio-crude oil and aqueous fraction were analyzed. Results indicated that reaction temperature greatly affected the distribution of chemical composition and functional groups of HTL bio-crude oil and aqueous fraction. The bio-crude oil with a higher percentage of aliphatic functional groups was obtained at higher reaction temperatures (280–320°C). Besides, the aqueous fraction recovered under the same operating conditions had a lower concentration of nitrogenous organic compounds (NOCs) with two or more methyl groups. The general reaction network for HTL of low-lipid microalgae was proposed. The specific reaction pathways for microalgae substrates were analyzed in terms of lipid, protein and non-fibrous carbohydrate based on the spectral analysis.
Patients with refractory hypercholesterolemia, who have high low-density lipoprotein (LDL) cholesterol levels despite treatment with lipid-lowering therapies at maximum tolerated doses, have an ...increased risk of atherosclerosis. In such patients, the efficacy and safety of subcutaneous and intravenous evinacumab, a fully human monoclonal antibody against angiopoietin-like 3, are not known.
In this double-blind, placebo-controlled, phase 2 trial, we enrolled patients with or without heterozygous familial hypercholesterolemia who had refractory hypercholesterolemia, with a screening LDL cholesterol level of 70 mg per deciliter or higher with atherosclerosis or of 100 mg per deciliter or higher without atherosclerosis. Patients were randomly assigned to receive subcutaneous or intravenous evinacumab or placebo. The primary end point was the percent change from baseline in the LDL cholesterol level at week 16 with evinacumab as compared with placebo.
In total, 272 patients were randomly assigned to the following groups: subcutaneous evinacumab at a dose of 450 mg weekly (40 patients), 300 mg weekly (43 patients), or 300 mg every 2 weeks (39 patients) or placebo (41 patients); or intravenous evinacumab at a dose of 15 mg per kilogram of body weight every 4 weeks (39 patients) or 5 mg per kilogram every 4 weeks (36 patients) or placebo (34 patients). At week 16, the differences in the least-squares mean change from baseline in the LDL cholesterol level between the groups assigned to receive subcutaneous evinacumab at a dose of 450 mg weekly, 300 mg weekly, and 300 mg every 2 weeks and the placebo group were -56.0, -52.9, and -38.5 percentage points, respectively (P<0.001 for all comparisons). The differences between the groups assigned to receive intravenous evinacumab at a dose of 15 mg per kilogram and 5 mg per kilogram and the placebo group were -50.5 percentage points (P<0.001) and -24.2 percentage points, respectively. The incidence of serious adverse events during the treatment period ranged from 3 to 16% across trial groups.
In patients with refractory hypercholesterolemia, the use of evinacumab significantly reduced the LDL cholesterol level, by more than 50% at the maximum dose. (Funded by Regeneron Pharmaceuticals; ClinicalTrials.gov number, NCT03175367.).
Monotonous luminescence has always been a major factor limiting the application of organic room‐temperature phosphorescence (RTP) materials. Enhancing and regulating the intermolecular interactions ...between the host and guest is an effective strategy to achieve excellent phosphorescence performance. In this study, intermolecular halogen bonding (CN⋅⋅⋅Br) was introduced into the host–guest RTP system. The interaction promoted intersystem crossing and stabilized the triplet excitons, thus helping to achieve strong phosphorescence emission. In addition, the weak intermolecular interaction of halogen bonding is sensitive to external stimuli such as heat, mechanical force, and X‐rays. Therefore, the triplet excitons were easily quenched and colorimetric multi‐stimuli responsive behaviors were realized, which greatly enriched the luminescence functionality of the RTP materials. This method provides a new platform for the future design of responsive RTP materials based on weak intermolecular interactions between the host and guest molecules.
Intermolecular halogen bonding (CN⋅⋅⋅Br) was introduced into the host–guest room‐temperature phosphorescence (RTP) system, achieving fluorescence–phosphorescence dual‐emission. The weak intermolecular interactions of the halogen bond are sensitive to external stimuli (heat, mechanical force and X‐rays), realizing the colorimetric multi‐stimuli response behaviors.
Well conducted: A two‐dimensional porphyrin covalent organic framework is described. Owing to the eclipsed stacking alignment, the framework is conductive and allows high‐rate carrier transport ...through the porphyrin columns (see picture). The central metal in the porphyrin rings changes the conducting nature of the material from hole to electron, and to ambipolar conduction. It also drives the high on–off ratio photoconductivity of the framework.
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