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Given the enormous safety risks and environmental pollution that restrict the green development of isocyanate produced by phosgene reactions, we propose a new green and intrinsically safe route for synthesizing diisocyanates containing the furan ring from 5-hydroxymethylfurfural. In this work, the following novel reactions have been systematically investigated, including synthesizing a new compound methyl furan-2,5-dimethylene dicarbamate (FDC) using 2,5-bis(aminomethyl)furan (BAF) and dimethyl carbonate (DMC), the selective hydrogenation of FDC to a new compound methyl tetrahydrofuran-2,5-dimethylene dicarbamate (THFDC), and FDC and THFDC catalytic decomposition to produce corresponding furan-2,5-dimethylene diisocyanate (FDI) and tetrahydrofuran-2,5-dimethylene diisocyanate (THFDI). The results showed that CH3ONa could effectively catalyze the synthesis of FDC from BAF and DMC, and the separation yield of FDC was 98.1% under mild conditions including a nBAF : nDMC ratio of 1 : 10 at 70 °C for 4 h. CH3ONa can be recycled up to four times with high stability. A 0.5% Pd/γ-Al2O3 catalyst with low Pd loading was prepared, and it showed high catalytic activity and stability for FDC hydrogenation to THFDC, with a THFDC yield of 99.9% at 100 °C, 2 MPa H2 and 1 h, and the catalyst could be reused after simple treatment with ethanol. The structure–activity relationship of supported Pd catalysts was studied. The conditions for the thermal decomposition reactions of FDC and THFDC were optimized, resulting in FDI and THFDI yields as high as 89.6% and 92.8%, respectively. Owing to the urgent need for raw materials sustainability and environmental friendliness, the brand-new safe pathway for synthesizing FDI and THFDI was constructed, significantly improving the competitiveness of the non-phosgene method in preparing bio-based isocyanate. [ABSTRACT FROM AUTHOR]

Er3+/Yb3+ codoped glass ceramics containing BaF2 crystals were obtained through a melt quenching process; the precipitation of BaF2 nanocrystals was confirmed by structural characterization. The effects of crystal quantity and size on the transmittance and upconversion fluorescence of the samples were analyzed. The precipitation of nanocrystals leads to a significant increase in upconversion luminescence intensity. The fluorescence spectra at different pump powers were measured. Er3+ and Yb3+ energy level diagrams and possible energy transfer routes during upconversion luminescence were explored. Furthermore, the functional relationship between temperature and the upconversion fluorescence intensity ratio of the samples was analyzed. When the temperature is 293 K, the relative sensitivity reaches the maximum of 1.38% K−1. [ABSTRACT FROM AUTHOR]

A bubble-based acoustofluidic filtration (BAF) microfluidic device, which employs cross-flow filtration (CFF) and acoustic streaming, separates cells with high efficiency for forensic analysis. Forensic samples are typically complex and contain a substantial number of squamous epithelial cells from the female vagina, which tend to have fouling problems during filtration due to their morphological and cell adhesion differences. To overcome this issue, the BAF device utilizes bubble oscillation by bulk acoustic wave (BAW) to generate acoustic streaming, which offers additional hydrodynamic forces for side flushing cleaning and achieves effective removal within a mere 0.5 seconds. Our device is tested with imbalanced cell mixtures of sperm and epithelial cells with large disparity ratios. By concurrently employing CFF and acoustic streaming, the samples with our sperm-enrichment can achieve 91.72–97.78% for the recovery rate and 74.58–89.26% for the purity in the sperm enrichment. They are further subjected to short tandem repeat (STR) profiling, enabling the identification of perpetrators. Notably, even samples with minimal sperm cells demonstrated a significant increase in the male donor DNA ratio, while the peak heights of female alleles became virtually undetectable. The exceptional cell separation capability demonstrated by our BAF device highlights its potential applications in forensic sciences and other areas of cell biology. [ABSTRACT FROM AUTHOR]

Fluorine (F) plays an important role in biology and geology but is hard to analyse and quantify using element-specific techniques. This is related to its high first ionisation potential and analytical methods depending on high energy sources for excitation and/or ionisation of F. In particular ICP-MS was initially found incapable of detecting F; however, recent methodological advances, i.e., the application of Ba as a plasma modifier and the application of tandem mass spectrometry, enabled its analysis by targeting BaF+. In this study, we suggest this approach in conjunction with laser ablation to perform the mapping of F in both biological and geological samples. In a proof of concept, tooth samples as biological samples and a Rhynie chert as a geological sample were analysed. For method development and to evaluate the performance of the developed method, gelatine-based F-standards were prepared and characterised using combustion ion chromatography. Standards were further interrogated to estimate LODs and LOQs. Depending on the required spatial resolution, figures of merit in the upper ng g−1 range and lower μg g−1 range were achievable. This is the first example of F mapping using LA-ICP-MS instrumentation and the developed methods close an important analytical gap by enabling the spatially resolved F analysis at relevant biological and geological concentrations. [ABSTRACT FROM AUTHOR]

Elemental analysis of fluorochemicals has received renewed attention in recent years stemming from the increased use of fluorinated compounds. However, fundamental drawbacks of in-plasma ionization have hindered ICPMS applications in this area. Recently, we have introduced post-ICP chemical ionization for BaF+ formation using Ba-containing reagent ions supplied by nanospray, leading to major improvements in F detection sensitivity. Here, we present further insights into this post-plasma chemical ionization. First, we examine the effect of oxygen introduced into the plasma (a necessity for organic solvent introduction) on BaF+ ion formation. The results indicate that excess plasma oxygen leads to abundant HNO3 in the post-plasma flow, shifting ionization reactions toward BaNO3+ formation and suppressing BaF+ sensitivity. To amend this, we utilize reagent ions with other metal centers to impart selectivity toward F detection. Our investigations show that robustness of F detection in the presence of abundant HNO3 improves in the order Al3+ ≈ Sc3+ > La3+ > Mg2+ > Ba2+ as the metal center in the reagent ions, consistent with the stronger metal–F bond in the series. Sc-based ionization resulting in ScNO3F+ shows the best balance between sensitivity and robustness in the presence of nitric acid. Similarly, this ion shows an improved tolerance relative to BaF+ for a Cl-containing matrix where HCl interferes with ionization. Finally, we demonstrate a unique feature of post-plasma chemical ionization for real-time flagging of matrix effects via monitoring reagent ions. These findings provide significant improvements of post-plasma chemical ionization for elemental F analysis, particularly for online chromatographic detection where solvent gradients are utilized. [ABSTRACT FROM AUTHOR]

Metal selenites and tellurites have demonstrated excellent second-harmonic generation (SHG) properties in inorganic solid compounds, such as strong SHG efficiency, a wide transparent range, appropriate birefringence, etc. During the past ten years, important progress has been achieved in this field. The largest SHG efficiency of selenites and tellurites reached 13.5 × KDP (BiFSeO3) and 2 × KTP (CdTeMoO6), respectively. The shortest UV absorption edge of tellurites has been pushed to 205 nm in BaF2TeF2(OH)2 successfully. In terms of the chemical compositions, research studies are no longer concentrated on d0 transition metal compounds only, and the most electronegative fluorine has been used increasingly to widen the optical bandgaps and enrich the structural types of the materials. This paper reviewed the recent developments of selenite and tellurite based SHG materials. Challenges in creating new high powered SHG materials and perspectives for future work are presented. [ABSTRACT FROM AUTHOR]

A series of high quality x%Pr3+:BaF2 (x = 0.6, 1, 2); (1%Pr3+, 2%Na+):BaF2; (1%Pr3+, y%Ca2+):BaF2 (y = 3, 5) and (0.6%Pr3+, 10%R3+):BaF2 (R = Y, Lu, Gd) crystals were grown by temperature gradient technique (TGT). The Raman spectra, absorption spectra, fluorescence spectra, and fluorescence decay lifetime were measured. XRD patterns indicate that the as-synthesized samples are pure BaF2 phase. The absorption cross-section of Pr3+ ions in the BaF2 matrix can be greatly improved by co-doping R3+ ions, while improvement by Na+ and Ca2+ ions is marginal. The fluorescence characteristic of Pr3+ ions can be effectively regulated by co-doping Na+, Ca2+, R3+ (R = Y, Lu, Gd) ions of different valence states. When R3+ ions are introduced, the fluorescence spectra show the strongest orange emission and the CIE chromaticity coordinates of Pr3+ ions are also in the orange region. When single-doped Pr3+ ions and Na+ or Ca2+ ions are introduced, the fluorescence lifetime of the 3P0 level is double exponential decay, and the short lifetime is the main proportion. However, the fluorescence centers tend to homogeneous and stable by R3+ ions co-doping and the fluorescence lifetime exhibits single-exponential decay, which is fitted to 49.7 μs, 47.8 μs and 49.6 μs of (0.6%Pr3+, 10%R3+):BaF2 (R = Y, Lu, Gd), respectively. All the results show that (Pr3+, Gd3+):BaF2 and (Pr3+, Na+):BaF2 are excellent laser gain media for high-efficiency orange and red laser operation. [ABSTRACT FROM AUTHOR]

Increased applications of fluorochemicals have prompted development of elemental methods for detection and quantitation of these compounds. However, high-sensitivity detection of fluorine is a challenge because of difficulties in excitation and ionization of this element. Recently, a new approach has emerged to detect F as a diatomic ion (BaF+) in inductively coupled plasma mass spectrometry (ICP-MS). However, formation of this species in the high-temperature plasma is inefficient, leading to low sensitivities. Here, we introduce a post-ICP chemical ionization approach to enhance analytical performance for F detection in liquid samples. Solutions of fluorochemicals are introduced into an ICP leading to formation of HF in the afterglow. Subsequently, reagent ions from nanospray of sodium acetate and barium acetate electrolytes are utilized to ionize HF to Na2F+ and BaF+, respectively, via post-plasma ion-neutral reactions. Both ions provide substantially better sensitivities compared to that of BaF+ formed inside the plasma in conventional ICP-MS methods. Notably, post-plasma BaF+ offers a sensitivity of 280 cps ppb−1 for F, near two orders of magnitude higher than that of conventional ICP-MS methods. Compound-independent response for F from structurally diverse organofluorines is confirmed by monitoring BaF+ and a limit of detection (LOD) of 8–11 ng mL−1 F is achieved. Importantly, isobaric interferences are substantially reduced in chemical ionization, leaving F background as the main factor in LOD determination. Insights into BaF+ formation via experimental and computational investigations suggest that BaNO2+ and Ba(H2O)n2+ serve as reagent ions while nonreactive BaCH3CO2+ is the dominant ion produced by nanospray. The facile development of effective post-plasma ionization chemistries using the presented approach offers a path for further improvements in F elemental analysis. [ABSTRACT FROM AUTHOR]

Scintillators, which can emit visible photons under γ- or X-ray excitation, are widely used in radiation detection. Traditional inorganic scintillators usually have some drawbacks, such as hygroscopicity or a high synthesis temperature, and most of them are poisonous. Hence, we report the synthesis of metal iodate scintillators (Eu(IO3)3 and Tb(IO3)3) by a facile hydrothermal reaction that exhibit good radioluminescence (RL) intensity. To further increase the RL intensities, we prepared Eu(IO3)3:xSm and Tb(IO3)3:xGd with stronger RL intensities and higher sensitivities than BaF2 and PbWO4 powders when x = 3%. Furthermore, we obtained scintillating films consisting of Eu(IO3)3:3%Sm and Tb(IO3)3:3%Gd for X-ray imaging. Our Eu(IO3)3:3%Sm and Tb(IO3)3:3%Gd films revealed excellent luminescence under high-energy X-ray excitation and spatial resolutions down to 9 lp mm−1 and 8 lp mm−1, respectively. Thus, these films can be regarded as candidate materials for X-ray imaging. [ABSTRACT FROM AUTHOR]

A succession of Ce3+ and Tb3+ co-doped BaF2 nanoparticles were synthesized by co-precipitation and hydrothermal methods. The structure, morphology, elemental composition and photoluminescence characteristics of the doped samples were studied by X-ray diffractometry (XRD), transmission electron microscopy (TEM), X-ray energy spectrometry (EDX), photoluminescence emission spectroscopy (PL) and photoluminescence excitation spectroscopy (PLE). The phosphor has a cubic structure. According to the energy level relationship between Ce3+ and Tb3+, the energy transfer mechanism of Ce3+ and Tb3+ co-doped BaF2 samples was analyzed. Ce3+, Tb3+ co-doped BaF2 shows a strong green emission, and its fluorescence emission intensity is about 9 times higher than that of Tb3+ single doped BaF2. The energy transfer efficiency from Ce3+ to Tb3+ was calculated using a formula, and it was found that the energy transfer efficiency could reach up to 88.22%. The detection solution was prepared by uniformly dispersing the phosphor in absolute ethanol. Through a comparative study of a series of metal ions, it was found that the detection solution has a peculiar sensitivity to aqueous solutions containing Cu2+. At the same time, the relationship between the fluorescence intensity of the detection solution and the concentration of Cu2+ was studied, and the cause of fluorescence quenching caused by Cu2+ ions was analyzed from the perspective of energy transfer. From this work, it is considered that the phosphor has a great potential application in the determination of Cu2+ in practical wastewater. [ABSTRACT FROM AUTHOR]

Glasses with the mol% compositions 1.88 Na2O·15.04 K2O·7.52 Al2O3·69.56 SiO2·6.00 BaF2 and 1.88 Na2O·15.03 K2O·7.52 Al2O3·69.52 SiO2·6.00 BaF2·0.05 SmF3 were studied using X-ray diffraction, transmission electron microscopy, and anomalous small-angle X-ray scattering (ASAXS). While the glass doped with samarium showed liquid/liquid phase separation of droplets with sizes of around 100 nm, the glass without samarium did not. The samples were annealed at 580 °C or at 600 °C which led to the crystallization of cubic BaF2. The X-ray diffraction patterns showed strongly broadened lines. Hence, the BaF2 crystals possess sizes in the nm range. ASAXS gave evidence of a core shell structure. In agreement with earlier studies, it is assumed that the shell acts as a diffusion barrier that hinders crystal growth. Surprisingly, the cores and shells from the crystallization of the homogeneous glass and from the second glass, which is Sm-doped and shows liquid/liquid phase separation, both possess similar dimensions, even though the origin of the barrier is very different. The doped samples show long luminescence lifetimes of nearly 5 ms at a wavelength of 600 nm, which is nearly as long as those in fluoride phosphate glasses. [ABSTRACT FROM AUTHOR]

A simple and general dried droplet calibration approach was developed for the quantitative analysis of elements in inorganic nonmetallic materials using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). For quantitative analysis, the elemental distribution in dried droplets was improved by optimizing the amount of a surfactant (Pluronic F-127) added into the calibration solutions and the drying temperature. Under optimal conditions, at 2.0 wt% Pluronic F-127 in the calibration solutions and a drying temperature of 85 °C, the relative standard deviation of the signal intensity obtained from multi-line ablation mode is less than 20% for dried droplets. Meanwhile, the experimental results revealed that dried droplets have no effect on the ablation of the sample and dried droplets can be totally ablated in one ablation raster. Further, the method was applied to analyze several inorganic non-metallic materials such as yttrium aluminum garnet (YAG) ceramic, BaF2 crystal, and NIST SRM 612 glass. The linear correlation coefficients of the calibration curves ranged from 0.9936 to 0.9999 without any internal standard correction. Moreover, the results agree well with the results obtained by inductively coupled plasma atomic emission spectrometry or inductively coupled plasma atomic mass spectrometry and certified values. [ABSTRACT FROM AUTHOR]

New coordination polymers with 2D network structures with fluorine directly coordinated to the metal ion were prepared both via mechanochemical synthesis and fluorolytic sol–gel synthesis. Depending on the synthesis route, the samples show different particle sizes, according to SEM imaging. The crystal structures of barium acetate fluoride, strontium acetate fluoride, and lead acetate fluoride (BaF(CH3COO), SrF(CH3COO) and PbF(CH3COO)) were solved from X-ray powder diffraction data. The structure solution is backed by the results from 19 F MAS NMR, FT IR data, and thermal analysis. The calculated chemical shifts of the 19 F MAS NMR spectra coincide well with the measured ones. It turns out that the grinding conditions have a remarkable influence on the mechanochemical synthesis and its products. Our systematic study also indicates a strong influence of the atomic radii of Ca, Sr, Ba, and Pb on the success of the syntheses. [ABSTRACT FROM AUTHOR]

Phase pure BaF2 doped with Ce3+ (0.1%) nanocrystals are synthesized using an ionic liquid (IL) ([C4mim][BF4]) assisted solvothermal method where the IL is not only used as a reaction medium and a capping agent, but also as a reaction partner. Subsequently, upon calcining the as-prepared nanocrystals at various temperatures (200, 400, 600 and 800 °C), athough the crystal phase remains the same, however, a significant change in the lattice strain and morphology is observed. Tensile strain appears in the nanocrystals calcined at temperatures up to 400 °C, but a reversal of the strain, i.e. compressive strain, takes place when calcination is performed at 600 °C and onwards. Nanoflakes are obtained until calcination at 400 °C. However on calcination at 600 °C and beyond, a drastic modification in the morphology is observed. Layer or step-like structures appear due to secondary nucleation of nanoparticles. Meanwhile, the photoluminescence (PL) intensity of Ce3+ ions gradually decreases with the calcination temperature and finally vanishes at 600 °C/800 °C. To investigate the reasons for the quenching of the PL intensity, thermally stimulated luminescence (TSL) and thermally stimulated exoelectron emission (TSEE) measurements are performed. The TSL and TSEE results indicate that in addition to the domination of deeper electron traps that appear as a high-temperature shift of TSEE glow peaks for both 600 °C and 800 °C, some new types of defects like F vacancies (F-centers) can be present, especially in the 800 °C calcined sample. The conditions leading to the quenching of Ce3+ luminescence in the nanoparticles are analyzed and discussed. [ABSTRACT FROM AUTHOR]