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The P-loop fold nucleoside triphosphate (NTP) hydrolases (also known as Walker NTPases) function as ATPases, GTPases, and ATP synthases, are often of medical importance, and represent one of the largest and evolutionarily oldest families of enzymes. There is still no consensus on their catalytic mechanism. To clarify this, we performed the first comparative structural analysis of more than 3100 structures of P-loop NTPases that contain bound substrate Mg-NTPs or their analogues. We proceeded on the assumption that structural features common to these P-loop NTPases may be essential for catalysis. Our results are presented in two articles. Here, in the first, we consider the structural elements that stimulate hydrolysis. Upon interaction of P-loop NTPases with their cognate activating partners (RNA/DNA/protein domains), specific stimulatory moieties, usually Arg or Lys residues, are inserted into the catalytic site and initiate the cleavage of gamma phosphate. By analyzing a plethora of structures, we found that the only shared feature was the mechanistic interaction of stimulators with the oxygen atoms of gamma-phosphate group, capable of causing its rotation. One of the oxygen atoms of gamma phosphate coordinates the cofactor Mg ion. The rotation must pull this oxygen atom away from the Mg ion. This rearrangement should affect the properties of the other Mg ligands and may initiate hydrolysis according to the mechanism elaborated in the second article. [ABSTRACT FROM AUTHOR]

The paper presents experimental results on the solubility of fluorides in fluid-saturated melt of alkaline ultrapotassic syenite-porphyry from the Gross gold ore deposit in southern Yakutia at T = 600–800°C, P = 150–260 MPa. The experiments were carried out to confirm the assumption of high solubility of fluorine in ultrapotassic syenite melt, which could contribute to the formation of specific and low-viscosity melts that were emplaced in the form of a syenite porphyry sill. The solid products after the experiments contained aluminosilicate glass, potassium feldspar, fluorite, quartz, and two fluoride phases differing in composition (potassium and aluminum fluoride and potassium and magnesium fluoride). The experimental results led us to determine a high maximum solubility of fluorine in the melt: up to 4.2–4.6 wt %, with the maximum F content found in the lowest temperature melt at 625°C. The solidus and liquidus temperatures of the syenite melt were estimated at 600–625 and 650–800°C, respectively. The aqueous fluoride fluid coexisting in equilibrium with the melt was determined to be alkaline. Potassium feldspar was the first to crystallize from the melt in the experiments, which is consistent with what is observed in samples of the naturally occurring rocks. [ABSTRACT FROM AUTHOR]

• Propose a new method for preparing AF 3 that the carbon residue as a raw material. • Fluoride weas converted to AF 3 through roasting with anhydrous Al 2 (SO 4) 3. • The roasting leaching method was utilized to obtain 94.30 % purity AF 3. • The overall recovery rate of fluorine throughout the entire process was 94.56 %. The carbon residue is a hazardous waste generated by the aluminum electrolysis production process, which contains a large amount of electrolyte fluoride salts. In order to recover the electrolyte components in carbon residue, this paper proposes a new method of using carbon residue to prepare aluminum fluoride by converting Na 5 Al 3 F 14 and Na 3 AlF 6 in carbon residue into aluminum fluoride to realize the recycling of fluoride in carbon residue. In the initial step, optimal parameters for carbon removal during roasting have been determined, including an oxygen flow rate of 7 g/min, a roasting temperature of 670 °C, and a roasting time of 80 min. The roasted clinker is obtained, and the removal rate of carbon reaches 99.95 % while the loss rate of fluorine is 0.48 %. In the second step, the mix anhydrous Al 2 (SO 4) 3 with roasted clinker for roasting. The optimal roasting temperature of 670 °C, the time of 10 min, and the mass ratio of anhydrous Al 2 (SO 4) 3 to roasted clinker of 5:5 could convert fluoride to AlF 3 products, with a conversion rate of 99.76 % and a loss rate of fluorine of 1.05 %. Finally, by removing sulfate impurities through water leaching for 15 min at 35 °C and with a liquid-solid ratio of 6 ml/g, the loss rate of fluorine is 3.98 %. This process yields AlF 3 with a purity of 94.30 %. The recovery rate of fluorine in the whole process is 94.56 %, which successfully achieves the recycling of fluorine in the carbon residue to obtain AlF 3 products. [Display omitted] [ABSTRACT FROM AUTHOR]

Ni 2 + bearing fluoro-aluminoborate glass composition [( AlF 3) x - (B 2 O 3) 0.63-x - (NiO) 0.2 - (Na 2 O) 0.35 ] was prepared via the melt-quenching method. The structure of glass was confirmed by X-Ray diffraction patterns, density, molar volume and infrared spectroscopy. The oxygen and fluorine bonds with the other constituent cations are the backbone of network. Additionally, the ligand field transitions of nickel ions were assigned for octahedral and tetrahedral forms. Unexpectedly, the addition of fluorine, mixed with oxygen, increased the splitting energy of 3d-orbitals of Ni 2 + ions. This unexpected behavior is back to the influence of the high field intensity of aluminum cations at the expense of boron cations. The splitting energy of 3d-orbitals (10Dq) increased, while inter-electronic repulsion parameters (B and C) decreased. The chemical bonding nature was evaluated. The color variation of samples from dark brown to light brown was explained. Furthermore, the optical band gap decreased owing to the high delocalization of electrons. • The intense to light brown color confirmed the existence of Ni2+ cations. • With increasing the AlF 3 /B 2 O 3 contents, the conversion from BO 4 to BO 3 increased. • An increase in the crystal field splitting and an increase in Racah parameters. • The bonding nature between the Ni cations and their surroundings is more covalent. [ABSTRACT FROM AUTHOR]

Reasonable mathematical derivation and mechanism model in the process of producing aluminum fluoride by fluosilicic acid is the key to the industrial treatment of fluorine resources in the tail gas of phosphate ore. In this work, aluminum fluoride was generated directly by fluosilicic acid to extract fluorine from the tail gas of phosphate rock. The uncreated-core model dominated by interfacial reaction and the uncreated-core model dominated by internal diffusion-reaction were then respectively utilized to describe the reaction kinetics of the generation of aluminum fluoride. The result showed that the uncreated-core model was dominated by interface reaction and internal diffusion, the apparent reaction order n = 1, and the activation energy Ea = 30.8632 kJ · mol–1. Product characterization and kinetic analysis were employed to deduce the reaction mechanism of preparing aluminum fluoride. The theoretical basis for the low-cost recycling of fluorine resources in the tail gas of industrial phosphate ore was provided in this work. [ABSTRACT FROM AUTHOR]

We report herein an efficient and fully automated protocol for the radiosynthesis of [18F]FAPI‐74, a new positron emission tomography (PET) radiopharmaceutical for in vivo detection of the fibroblast activation protein. [18F]FAPI‐74 was synthesized via a rapid [18F]aluminum fluoride coordination reaction, which was first developed on the flexible GE TRACERLab FX2N (FXN) platform and later translated to the cassette‐based module Trasis AllInOne (AIO). The results obtained with both modules were comparable in terms of yield and reproducibility. Automation of [18F]FAPI‐74 radiosynthesis on the FXN was carried out in 35 min with a radiochemical yield (RCY) of 18.5 ± 2.5% (n = 5, relative to starting [18F]fluoride). Method transfer to the AIO platform following minor optimizations allowed for the production of [18F]FAPI‐74 in an isolated RCY of 20 ± 2.5% [n = 3] with an overall synthesis time of 40 min. The radiochemical purity was greater than 95% for [18F]FAPI‐74, obtained from both modules. Overall, the protocol reliably provides a sterile and pyrogen‐free good manufacturing practice (GMP) compliant product of [18F]FAPI‐74 suitable for clinical PET imaging. [ABSTRACT FROM AUTHOR]

Human guanylate‐binding protein 1 (hGBP‐1) shows a dimer‐induced acceleration of the GTPase activity yielding GDP as well as GMP. While the head‐to‐head dimerization of the large GTPase (LG) domain is well understood, the role of the rest of the protein, particularly of the GTPase effector domain (GED), in dimerization and GTP hydrolysis is still obscure. In this study, with truncations and point mutations on hGBP‐1 and by means of biochemical and biophysical methods, we demonstrate that the intramolecular communication between the LG domain and the GED (LG:GED) is crucial for protein dimerization and dimer‐stimulated GTP hydrolysis. In the course of GTP binding and γ‐phosphate cleavage, conformational changes within hGBP‐1 are controlled by a chain of amino acids ranging from the region near the nucleotide‐binding pocket to the distant LG:GED interface and lead to the release of the GED from the LG domain. This opening of the structure allows the protein to form GED:GED contacts within the dimer, in addition to the established LG:LG interface. After releasing the cleaved γ‐phosphate, the dimer either dissociates yielding GDP as the final product or it stays dimeric to further cleave the β‐phosphate yielding GMP. The second phosphate cleavage step, that is, the formation of GMP, is even more strongly coupled to structural changes and thus more sensitive to structural restraints imposed by the GED. Altogether, we depict a comprehensive mechanism of GTP hydrolysis catalyzed by hGBP‐1, which provides a detailed molecular understanding of the enzymatic activity connected to large structural rearrangements of the protein. Database: Structural data are available in RCSB Protein Data Bank under the accession numbers: 1F5N, 1DG3, 2B92. [ABSTRACT FROM AUTHOR]

The current status of cathode materials for lithium‐sulfur (Li−S) battery is not satisfactory for full‐scale commercial production. This mainly stems from the unsolved problems associated with the polysulfide shuttle, which leads to lower sulfur utilization and significant capacity decay after a few hundred cycles. To better confine sulfur and its associated polysulfides, a core/double‐shelled nanocomposite was synthesized. The inner shell was composed of a carbon nanosphere with high conductivity, while the outer shell was an ultra‐thin aluminum fluoride (AlF3) layer to better retain polysulfides in the cathode structure. The AlF3 coating increased the initial discharge capacity to 1191 mA h g−1 with capacity retention of 76.3% and Coulombic efficiency > 99% over 100 cycles. Taking advantage of this tailored design, a reversible capacity of 702 mA h g−1 over 500 cycles at 1 C was achieved with only 0.052% capacity decay per cycle. This impressive electrochemical performance was ascribed to the enhanced conductivity and effective entrapment of polysulfides. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Carbon-containing AlF 3 catalysts were prepared using organic aluminum precursors. • Incomplete decomposition of organic precursors resulted in the formation of carbonaceous species. • C-AlF 3 composite catalysts were active and stable for dehydrofluorination of HFC-245fa. • Catalyst deactivation was due to coke deposition on the catalyst surface. • Pre-deposited carbonaceous species in the catalyst blocked strong acid sites of AlF 3. Abstract A series of C-AlF 3 composite catalysts were prepared using a sol-gel method and different aluminum precursors (i.e. aluminum isopropoxide (Al(O i Pr) 3) and aluminum diacetate hydroxide (C 4 H 7 AlO 5)). These catalysts were very active in gas-phase dehydrofluorination of 1, 1, 1, 3, 3-pentafluoropane. For example, a catalyst calcined at 400 °C with aluminum isopropoxide as the precursor (denoted as C-AlF 3 -AIP-400) gave a reaction rate of 8.30 μmol s−1 g cat -1 and a selectivity to 1, 3, 3, 3-tetrafluoropropene (HFO-1234ze) of above 99% at 340 °C. More importantly, the C-AlF 3 catalysts showed excellent stability during 100 h reaction, while the pure AlF 3 catalyst suffered severe deactivation owing to the coke deposition on the surface. In contrast, pre-deposited carbonaceous species formed in the catalyst due to the incomplete decomposition of organic precursors during the preparation procedure, which blocked strong acidic sites in the AlF 3 and thus maintained the catalyst stability. Therefore, these findings provide useful information on the development of efficient catalyst for this reaction, particularly on the maintainance of catalyst stability. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The main forms of Al-F complex ion groups in Na 3 AlF 6 molten salt are [AlF 4 ]−, [AlF 5 ]2− and [AlF 6 ]3−. • There is covalent interaction between Al-F in molten salt and electrons transfer from Al-3p orbital to F-2p orbital. • Raman spectra of [AlF 4 ]−, [AlF 5 ]2− and [AlF 6 ]3− are calculated at 595 cm−1, 547 cm−1 and 436 cm−1. Abstract First-principles molecular dynamics simulation (FPMD) has been applied to study the ionic structure and electronic properties of Na 3 AlF 6 molten salt. The results show that the main forms of complex ion groups in molten salt are [AlF 4 ]−, [AlF 5 ]2− and [AlF 6 ]3−, with the proportion of 10%, 60% and 30%, respectively. The electron orbitals near Fermi level are mainly occupied by F-2p and hybridize with Al-3p orbitals, in which electrons are transferred from Al-3p orbitals to F-2p orbitals. The calculation results of Raman spectra on [AlF 4 ]−, [AlF 5 ]2− and [AlF 6 ]3− are close to the experimental values, indicating FPMD is applicable to similar molten salt systems. [ABSTRACT FROM AUTHOR]

The preparation of CH3F via vapor phase catalytic fluorination of CH3OCH3 promoted by AlF3 (H‐AlF3, M‐AlF3, L‐AlF3) with different surface areas was investigated, with the reaction occurring as follows: CH3OCH3 +2 HF → 2CH3F + H2O. It was found that H‐AlF3 exhibited the highest catalytic activity with high stability among the three types of AlF3 tested in the 100‐h life‐span test, which can be attributed to the massive amount of amorphous AlF3 in H‐AlF3. H‐AlF3 contains the highest amount of acid and largest surface area among the AlF3 species. The synthetic route of CH3F showed higher conversion of raw material and better selectivity for CH3F than traditional routes. Fluoromethane was prepared via the vapor‐phase catalytic fluorination of CH3OCH3 by AlF3 catalyst. It was found that the amorphous AlF3 owned better activity than γ‐AlF3 or ɑ‐AlF3. [ABSTRACT FROM AUTHOR]

Abstract High strength, lightweight mullite whisker skeleton porous materials were prepared via novel facile nonaqueous precipitation method. The phase transition process of precipitate, microstructures and phase compositions of samples, and effects of aluminum fluoride amount on morphologies and properties of mullite whisker skeleton porous materials were investigated by DTA-TG, FE-SEM, XRD, the acid solubility and compressive strength tests. The growth direction of the whisker was determined. The growth mechanism of mullite whisker and formation mechanism of skeleton porous material were also investigated. The results show that the mullite phase forms at a low temperature of 900 °C via nonaqueous precipitation method, due to the formation of Al-O-Si bonds in the precipitate. The formation of mullite whiskers is controlled by gas-solid reaction and the whiskers grow along [001] direction. Well-developed mullite whiskers interlacedly grow into skeleton porous material at 1100 °C. The optimum mullite whisker skeleton porous material with the optimized aluminum fluoride amount of 1.3 of theoretical amount exhibits attractive properties of low density (1.21 g cm−3), high strength (158.6 MPa), low acid solubility (1.58 wt%), low thermal expansion coefficient (1.6 × 10−6 °C−1) and low thermal conductivity (0.28 W/(m K)). This material has the mean pore size of 542 nm and pore size distribution of 32–865 nm. It shows attractive application prospects in filtering and biomedical applications. [ABSTRACT FROM AUTHOR]

Aluminium chlorofluoride (ACF) and high-surface aluminium fluoride (HS-AlF3) were analyzed by a set of characterization methods to assess their acidic properties: NH3-TPD, CO adsorption followed by DRIFTS, CD3CN-PAS-FTIR and MAS NMR spectroscopy after 15N-pyridine adsorption. Both catalysts contain very strong and medium-strong Lewis acid sites as confirmed by CO adsorption, in which small differences arise from the morphological properties of each catalyst, with ACF being microporous and HS-AlF3 mesoporous. Shifts of the CO vibration band of up to 77 cm−1 were observed, which account for very strong Lewis acid sites. In addition, very strong Lewis acid sites could be identified by CD3CN-PAS for both catalysts, exhibiting a shift of 95 cm−1 from free nitrile, the highest ever reported for a solid Lewis acid. [ABSTRACT FROM AUTHOR]

The significant role played by water in the mechanochemical synthesis of highly distorted aluminum hydroxide fluorides is on the main focus of this research paper. The importance of water in the synthesis was evaluated considering separately combinations of O/OH sources (Al(OH)3, Al2O3) and fluorine sources with or without structural water (β-AlF3.3H2O, α-AlF3). Each system was studied by typical bulk and surface characterization techniques (XRD, MAS NMR, DTA-TG, NH3-TPD) and compared to each other in order to gain a more comprehensive insight of the importance of including water in the synthesis of amorphous aluminum hydroxide fluorides. [ABSTRACT FROM AUTHOR]

Aluminium salts are widely investigated for the coagulation process for removal of fluoride, but the residual Al above the acceptable limit is the main concern which is mainly due to the formation of soluble and colloidal Al-F complexes of aluminium and fluoride. Hence, it is necessary to investigate the nature and mechanism of formation of colloidal, dissolved and precipitated Al-F complexes and other Al associated species, that govern the concentration of residual Al in the defluoridated water. In the present study, experiments were performed to find the optimized dosage of aluminium sulfate (alum) and polyaluminium (PACl) for removal of fluoride from drinking water. Residual fluoride, turbidity and TDS were found to be 1.3 ppm, 7 NTU & 280 ppm respectively, for alum and 0.48 ppm, 4 NTU & 200 ppm respectively for PACl for initial fluoride concentration of 4 ppm. Residual Al was found to be above the acceptable limit (0.2 ppm), but it was less for PACl as compared to alum, however, after the subsequent microfiltration, residual Al was 0.268 & 0.13 for alum & PACl respectively that almost met the acceptable limit. Characterization of the treated water before and after filtration by using microfiltration membrane was done through electrospray ionization mass spectroscopy (ESI-MS) to identify the colloidal, dissolved Al-F species. Aluminium species in the form AlF 5 2− ,AlF 2 + , AlF 4 − , Al 2 (OH) 2 2+ , Al(OH) 2 + , Al(OH) 2 F 2 − , AlOHF + etc. as Al-F were recognised. From the ESI-MS results, it was observed that only a few Al-F complexes with lesser concentrations were formed in case of PACl, which confirmed the fact that PACl worked better for the fluoride removal with low residual Al. The settling of the Al-F complexes for PACl was better than alum due to the difference in flocculation mechanism bridging in case of PACl and sweep flocculation for alum. XRD, SEM & FT-IR analysis of alum and PACl sludge was done to identify the precipitated species. [ABSTRACT FROM AUTHOR]

Quasibinary phase diagrams of the system “low-melting cryolite-Sc2O3” the potential media for synthesizing alloyed alloys Al-Sc are plotted by the method of thermal analysis. The phase diagrams of (KF-NaF-AlF3)-Sc2O3 with different content of NaF and the cryolite ratio (CR) 1.3 and 1.5 are the diagrams with simple eutectics. The liquidus temperature of the (KF-AlF3)-Sc2O3 system increases with the increase in the Sc2O3 concentration due to the formation of a high-melting compound: potassium hexafluoroscandiate К3ScF6. The solubility of Sc2O3 in low-melting cryolite melts KF-NaF-AlF3 increases with the increase in temperature and CR. In contrast Al2O3, the solubility of Sc2O3 in melts containing KF-AlF3 with CR = 1.3-1.5 is much lower than in cryolite melts containing NaF. The conductivity of low-melting cryolite melts measured by the method of impedance spectroscopy decreases in proportion to the Sc2O3 concentration in the similar way as in salt melts containing Al2O3. Based on the experimental data obtained, the compositions of low-melting cryolite melts are proposed for the synthesis of doped Al-Sc alloys. [ABSTRACT FROM AUTHOR]

Gas-phase dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) to 1,3,3,3-tetrafluoropropene (HFO-1234ze), one of the new fourth-generation refrigerants was performed over the mesoporous nano -aluminum fluoride ( nano -AlF 3 ) synthesized through a facile polyol mediated sol-gel process. The solvent, molar ratio of HF/Al precursor and calcination temperature during preparation can affect the crystal structures and textural properties, especially the acidity amount of the resulting nano -AlF 3 . The prepared nano -AlF 3 catalysts exhibit the apparent reaction rate among 5.5–7.7 mmol h −1  g −1 with total selectivity above 97% to HFO-1234ze at 280 °C, which are higher than those on conventional β-AlF 3 and fluorinated Cr 2 O 3 catalysts. With regard to intrinsic reaction rate and apparent turn over frequency (TOF), β-AlF 3 displays the highest activity among the tested catalysts. The characterization results reveal that the density of acid sites of nano -AlF 3 is associated with its TOF in this reaction, and reducing the density of acid sites is beneficial to achieving high activity. However, the distribution of cis, trans-isomers for HFO-1234ze is not easily tuned by adjusting the preparation conditions of nano -AlF 3 . Catalytic stability tests show that nano -AlF 3 exhibits almost constant activity over 200 h, which are much more stable than conventional AlF 3 and fluorinated Cr 2 O 3 catalysts. [ABSTRACT FROM AUTHOR]

Porous mullite with interlocked needle shape microstructure was developed from China clay and aluminium fluoride trihydrate (AlF 3 ·3H 2 O). The effects of various parameters like sintering temperature, sintering time and the amount of AlF 3 ·3H 2 O on the phase evolution, microstructure and porosity have been studied. Quantitative analysis of mullite was carried out using X-ray diffraction combined with Rietveld-RIR method (Internal standard method). Porous mullite ceramics with 62% open porosity have been prepared at a relatively lower temperature of 1400 °C. The results show that the nucleation of mullite can be achieved from 700 °C onwards using hydrated aluminium fluoride without the formation of intermediate topaz crystals. The high amount of water vapour produced within the system during the in-situ reaction has a crucial role in deciding the reaction mechanism. [ABSTRACT FROM AUTHOR]

Introduction Equilibrium single-photon radionuclide imaging methods for assessing cardiac function and the integrity of the vascular system have long been in use for both clinical and research purposes. However, positron-emitting blood pool agents that could provide PET equivalents to these (and other) clinical procedures have not yet been adopted despite technical imaging advantages offered by PET. Our goal was to develop a PET blood pool tracer that not only meets necessary in vivo biological requirements but can be produced with an uncomplicated and rapid synthesis method which would facilitate clinical translation. Herein, albumin labeled with fluorine-18 was synthesized using a one-pot method and evaluated in vitro and in vivo in rats. Methods A ligand (NODA-Bz-TFPE), containing NODA attached to a tetrafluorophenylester (TFPE) via a phenyl linker (Bz), was labeled with aluminum fluoride (Al[ 18 F]F). Conjugation of the serum albumin with the ligand (Al[ 18 F]F-NODA-Bz-TFPE), followed by purification (size exclusion chromatography), yielded the final product (Al[ 18 F]F-NODA-Bz-RSA/HSA). In vitro stability was evaluated in human serum albumin by HPLC. Rat biodistributions and whole-body PET imaging over a 4 h time course were used for the in vivo evaluation. Results This synthesis exhibited an overall radiochemical yield of 45 ± 10% (n = 30), a 50-min radiolabeling time, a radiochemical purity >99% and apparent stability up to 4 h in human serum. Blood had the highest retention of Al[ 18 F]F-NODA-Bz-RSA at all times with a blood half-life of 5.2 h in rats. Al[ 18 F]F-NODA-Bz-RSA distribution in most rat tissues remained relatively constant for up to 1 h, indicating that the tissue radioactivity content represents the respective tissue plasma volume. Dynamic whole-body PET images were in agreement with these findings. Conclusions A new ligand has been developed and radiolabeled with Al[ 18 F]F that allows rapid (50-min) preparation of fluorine-18 serum albumin in one-pot. In addition to increased synthetic efficiency, the construct appears to be metabolically stable in rats. This method could encourage wider use of PET to quantify cardiac function and tissue vascular integrity in both research and clinical settings. [ABSTRACT FROM AUTHOR]

Individual transport numbers provide a measure of the charge ratio which is carried by each ionic species of an electrolyte. However, unlike the electrical conductivity or diffusion coefficients, this quantity lacks a clear definition from the statistical mechanics point of view. In practice, it is measured via complex experimental setups, and most of the interpretation of the available data is made by using the Nernst–Einstein approximation. Here we show that this approach is not suitable in molten salts due to the large contributions of the cross-terms due to the ionic interactions in the total ionic conductivity. We propose a partition scheme that allows to attribute these cross-terms to the various ions, allowing for an estimate of the transport numbers in a series of molten salt formed by mixing NaF and AlF 3 at various compositions. The results are interpreted using the speciation of the melt, which is characterized by the formation of various AlF x clusters. At large AlF 3 , the Na + ions are shown to contribute almost totally to the ionic conductivity. [ABSTRACT FROM AUTHOR]

A highly sensitive and selective fluorescence probe for H 2 O 2 has been developed based on an iminocoumarin derivative using aromatic boronic ester as sensing unit. A significant fluorescence enhancement was observed with λ max em = 619 nm when this probe was treated with H 2 O 2 . In the detection of H 2 O 2 , this probe exhibited a large Stokes shift (148 nm) and a low detection limit (6.0 × 10 −8  mol/L). Furthermore, cell imaging studies had revealed that this probe had the potential to detect intracellular H 2 O 2 in living cells. [ABSTRACT FROM AUTHOR]

The facile, rapid and bulk production of composite materials consisting of carbon nanostructures doped with metal-based compounds has been a significant challenge for various research areas where such types of materials can be applied, including catalysis, energy storage and water purification. In this work, a carbon foam‑aluminum fluoride composite (C-AlF 3 ) was developed by adopting a combustion synthesis approach, which is an attractive alternative to wet chemical methods usually employed for such purposes. The flame ignition and combustion of a solid-state mixture comprising a fluoropolymer and nano-sized Al powder leads to the formation of a porous carbon foam network doped with dispersed cubic-like AlF 3 nanoparticles (100 to 500 nm in size), as observed by high-resolution microscopy methods. Selective area electron diffraction and X-ray diffraction studies revealed a rhombohedral α-AlF 3 crystal structure for these embedded particles, while micro-Raman spectroscopy indicated typical carbonaceous features for the foamy matrix. The C-AlF 3 composite also showed a combination of micro-, meso- and macro-porous characteristics (i.e. pore sizes in the nanometer scale) based on the analysis of N 2 sorption data collected at 77 K. The findings of this study provide useful insights for further research on carbon-based nanocomposite materials prepared via direct combustion synthesis routes. [ABSTRACT FROM AUTHOR]

Introduction: Aluminium Fluoride (AlF3) intake produces oxidative stress resulting in brain damage. Although, Mucuna pruriens (Velvet bean) is commonly used in ayurvedic system of medicine for different neurological disorders. Its usefulness in oxidative stress induced behavioural and neuronal damage has received little attention. Aim: This study was conducted to evaluate the neuroprotective role of Mucuna pruriens against AIF3 induced behavioural and neuronal changes in rats. Materials and Methods: Thirty six male Wistar albino rats were divided into six groups as: I-Normal saline; II-AIF3; III-25 mg/kg Quercetin and AlF3; IV, V and VI received 50, 100 and 200 mg/kg Mucuna pruriens methanolic extract and AlF3 (600 ppm). Extract was given for 10 days followed by AlF3 treatment for next seven days. Behavioural parameters were assessed such as T-maze test, actophotometer, and rotarod followed by histopathological studies. Results: A reduction in the locomotor activity, spatial learning and motor coordination was observed in the animals of Group II which reversed when treated with Mucuna pruriens. The histopathological studies of hippocampal CA1 region also showed the neuroprotective role of this plant which occurred due to oxidative stress. Conclusion: This study suggests the potential neuroprotective ability of Mucuna pruriens against the change in behaviour and neuronal damage which occurred due to induction of AIF3. [ABSTRACT FROM AUTHOR]

This study examined the catalytic properties of AlF 3 nanostructures for the hydrolysis of NF 3 discharged from semiconductor processes. Alumina being used as a catalyst for the hydrolysis of NF 3 was converted to AlF 3 by fluorination in the presence of NF 3 during a gas-solid chemical reaction. In general, AlF 3 has low catalytic activity in the hydrolysis of fluorinated compounds, but its catalytic activity varies according to its crystal structure. Commercial AlF 3 exhibited low catalytic activity in the hydrolysis of NF 3 , whereas AlF 3 formed from the chemical reaction between NF 3 and alumina exhibited very high catalytic activity. Although alumina has high catalytic activity in the hydrolysis of NF 3 , its activity decreases as it is converted to AlF 3 during the process. On the other hand, the activity test and X-ray diffraction showed that its catalytic activity is recovered as the nanocrystals of AlF 3 were grown. AlF 3 nanocrystals grown by the gas-solid chemical reaction showed a similar distribution of acid sites as the alumina. These acid sites provided the catalytic activity of AlF 3 in the hydrolysis of NF 3 . [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy is a suitable measurement method for the investigation of electrical conductivity of new types of aluminium electrolytes. Low-temperature electrolytes together with inert electrodes represent an innovation of the aluminium electrolysis process. Electrical conductivity, as one of the most important properties of electrolytes, has been investigated and described as part of the studied area of low-temperature sodium cryolite mixtures. Electrolytes used in this study contained high content of aluminium fluoride, up to 45 mol %; the molar ratio of NaF to AlF 3 in the melts varied from 2.0 to 1.2. Mutual influence of commonly used additives in industrial electrolytes (AlF 3 , Al 2 O 3 , CaF 2 , MgF 2 , LiF) and their temperature dependence was determined. Electrical conductivity was measured using a tube-type cell with stationary electrodes applying AC -techniques with a sine wave signal in the high frequency range. Concentration and temperature dependences of the electrical conductivity for all the studied low-temperature multi-component systems were described by the regression equation. [ABSTRACT FROM AUTHOR]

The research presents the first results of aluminium speciation analysis in aqueous extracts of individual plant parts of Betula pendula and soil samples, using High Performance Ion Chromatography with Diode Array Detection (HPIC-DAD). The applied method allowed us to carry out a full speciation analysis of aluminium in the form of predominant aluminium–fluoride complexes: AlF ( x = 2,3,4) (3 − x ) (first analytical signal), AlF 2 + (second analytical signal) and Al 3 + (third analytical signal) in samples of lateral roots, tap roots, twigs, stem, leaf and soil collected under roots of B. pendula . Concentrations of aluminium and its complexes were determined for two types of environment characterised by different degree of human impact: contaminated site of the Chemical Plant in Luboń and protected area of the Wielkopolski National Park. For all the analysed samples of B. pendula and soil, AlF ( x = 2,3,4) (3 − x ) had the largest contribution, followed by Al 3 + and AlF 2 + . Significant differences in concentration and contribution of Al–F complexes and Al 3 + form, depending on the place of sampling (different anthropogenic pressure) and plant part of B. pendula were observed. Based on the obtained results, it was found that transport of aluminium is “blocked” by lateral roots, and is closely related to Al content of soil. [ABSTRACT FROM AUTHOR]

In this article, we report on the photoluminescence properties of c admium lead boro aluminum fluoride (CdPbBAlF) glasses as a function of various doping concentrations of Eu 3+ and Tb 3+ ions. The emission spectra of Eu 3+ : CdPbBAlF glasses have shown bright reddish emission at 613 nm ( 5 D 0 → 7 F 2 ) under the excitation at 395 nm and Tb 3+ : CdPbBAlF glasses exhibited intense green emission at 545 nm ( 5 D 4 → 7 F 5 ) with the excitation at 379 nm. The luminescence quenching behavior of the prepared glasses as a function of the doping molar concentration of Eu 3+ and Tb 3+ ions was analyzed, which could be useful for optimizing the potential composition towards the novel optical applications. Energy level diagram representing the emission lines and decay curves of the prominent emission transitions at 613 nm, 545 nm of Eu 3+ and Tb 3+ : CdPbBAlF glasses have been presented. [ABSTRACT FROM AUTHOR]

Amino acid residues 283–297 from sialic acid-binding immunoglobulin-like lectin 9 (Siglec-9) form a cyclic peptide ligand targeting vascular adhesion protein-1 (VAP-1). VAP-1 is associated with the transfer of leukocytes from blood to tissues upon inflammation. Therefore, analogs of Siglec-9 peptide are good candidates for visualizing inflammation non-invasively using positron emission tomography (PET). Gallium-68-labeled 1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid (DOTA)-conjugated Siglec-9 has been evaluated extensively for this purpose. Here, we explored two alternative strategies for radiolabeling Siglec-9 peptide using a 1,4,7-triazacyclononane-triacetic acid (NOTA)-chelator to bind [68Ga]Ga or [18F]AlF. The radioligands were evaluated by in vivo PET imaging and ex vivo γ-counting of turpentine-induced sterile skin/muscle inflammation in Sprague-Dawley rats. Both tracers showed clear accumulation in the inflamed tissues. The whole-body biodistribution patterns of the tracers were similar. [ABSTRACT FROM AUTHOR]

Many employees in the aluminum industry are exposed to a range of aluminum compounds by inhalation, and the presence of ultrafine particles in the workplace has become a concern to occupational health professionals. Some metal salts and metal oxides have been shown to enter the brain through the olfactory route, bypassing the blood-brain barrier, but few studies have examined whether aluminum compounds also use this pathway. In this context, we sought to determine whether aluminum was found in rat olfactory bulbs and whether its transfer depended on physicochemical characteristics such as solubility and granulometry. Aluminum salts (chloride and fluoride) and various nanometric aluminum oxides (13 nm, 20 nm and 40–50 nm) were administered to rats by intranasal instillation through one nostril (10 μg Al/30 μL for 10 days). Olfactory bulbs (ipsilateral and contralateral relative to instilled nostril) were harvested and the aluminum content was determined by graphite furnace atomic absorption spectrometry after tissue mineralization. Some transfer of aluminum salts to the central nervous system via the olfactory route was observed, with the more soluble aluminum chloride being transferred at higher levels than aluminum fluoride. No cerebral translocation of any of the aluminas studied was detected. [ABSTRACT FROM AUTHOR]

Functionalization reactions of the refrigerants HFO-1234yf (2,3,3,3-tetrafluoropropene) and HFO-1234ze (1,3,3,3-tetrafluoropropene) were developed. The selectivity and reactivity towards CF3 groups of C−F activation reactions can be controlled by employing either a germane or a silane as the hydrogen source. Unique transformations were designed to accomplish consecutive hydrogermylation and C−F activation steps. This allowed for an unprecedented transformation of an olefinic C−F bond into a C−H bond by heterogeneous catalysis. These reactions are catalyzed by nanoscopic aluminum chlorofluoride (ACF) under very mild conditions. [ABSTRACT FROM AUTHOR]

The paper presents the dosimetric characterization of lithium calcium aluminum fluoride doped with europium and yttrium (LiCaAlF 6 :Eu,Y), synthesized by simple melt process. The characterization involved thermoluminescence (TL), optically stimulated luminescence (OSL), photoluminescence (PL) spectra, OSL emission spectra, minimum measurable dose, fading, dose response and photon energy dependence measurements. The OSL sensitivity of this phosphor to ionizing radiation was found to be ∼20 times to that of commercially available Al 2 O 3 :C, whereas, the TL sensitivity was ∼2.5 times to that of CaSO 4 :Dy (0.05 mol%). Photoluminescence (PL) and OSL emission spectra suggest that the Eu 2+ ions are responsible for OSL emission. The reusability of OSL discs for 50 cycles for a test dose of 20 mGy has been established. Minimum detectable dose for the phosphor in continuous wave OSL (CW-OSL) mode was found to be 0.5 μGy with negligible fading post 9 days of irradiation. Owing to its excellent dosimetric characteristics the phosphor is a highly sensitive dosimetric grade phosphor and is a serious contender for various radiological applications. [ABSTRACT FROM AUTHOR]

The solution structure of AlMe2F and its reactivity with a prototypical ansa-metallocene have been investigated by advanced NMR techniques, in an attempt to indirectly shed some light on the structure and working principles of methylalumoxane (MAO) mixtures in olefin polymerization. In solution, AlMe2F gives rise to a complex equilibrium of oligomeric species, including a heterocubane [(Me2Al)4F4] tetramer, resembling the behavior of MAO. This complex mixture reacts with (ETH)ZrMe2 (ETH= rac-[ethylenebis(4,5,6,7-tetrahydro-1-indenyl)]) to afford [(ETH)ZrMeδ+(μ-F)(AlMe2F)nAlMe3δ−] inner-sphere ion pairs through successive insertions/deinsertions of AlMe2F units into the Zr⋅⋅⋅(μ-F) bond. [ABSTRACT FROM AUTHOR]

In this study, a single-step combustion process for the synthesis 1-D, 2-D, and 3-D micro and nanostructures of AlN was developed. The structures were grown by combustion of Al+ k AlF 3 (or ZnF 2 )+ m NH 4 Cl reaction mixture under 4.0 MPa nitrogen atmosphere. Based on experimental data, the growth conditions, morphology, and composition, optical, and thermal properties of AlN micro and nanostructures were determined. The formation of structures was associated with the combustion temperature, liquid and gas-phase reactions, and the type of additives used in the experiments. The new insight, we gleaned from this study may help in the selective growth of AlN micro and nanostructures of different morphology, enhancing their functionality. [ABSTRACT FROM AUTHOR]

The selective activation of C Cl bonds of hydrochlorofluoromethanes and chloromethanes at moderate reaction conditions using ACF in a combination with Et 3 GeH is presented. The reactions of the chloromethanes (CH 3 Cl, CH 2 Cl 2 , CHCl 3 and CCl 4 ) in the presence of Et 3 GeH and ACF as catalyst led to the activation of only one C Cl bond resulting in the hydrodechlorination. Friedel-Crafts reactions with benzene as solvent are suppressed by Et 3 GeH. A selective hydrodechlorination of hydrochlorofluoromethanes was achieved, because a transformation of a C F bond into a C H bond by the combination of ACF with Et 3 GeH did not occur. Supporting Pulse TA ® experiments illustrated the interaction between the solid catalyst and Et 3 GeH, the solvent benzene or CH 2 Cl 2 . [ABSTRACT FROM AUTHOR]

γ-Al 2 O 3 with 3/4 sphere and cabbage-like structures were prepared via hydrothermal synthesis. Then they were evaluated as catalysts for the dismutation of HCFC-22 as a model reaction for Cl/F exchange reactions and compared with a commercial γ-Al 2 O 3 . The results indicate that both hydrothermal samples are formed by the loose assembly of nano-sheets. For cabbage-like alumina, hollow structure is detected. Aluminum chlorofluoride (ACF) structure with strong Lewis acidity is beneficial for dismutation of HCFC-22. Following pre-fluorination by HCFC-22, the high activity of cabbage-like γ-Al 2 O 3 is attributed to the high content of ACF. It indicates that cabbage-like structure tends to form more ACF structure. [ABSTRACT FROM AUTHOR]

β-amyloid (Aβ) is produced from a precursor membrane protein by normal proteolytic processing as a soluble peptide of 39-43 amino acids. Under unknown conditions, Aß aggregates and accumulates to form amyloid fibrils. Exposure to certain metal ions, including aluminum, has been proposed as a risk factor in developing Alzheimer disease. Until now the mode of aluminum binding has not been completely explained. In this study we focus on the binding affinities of [Al(H2O)6]3+ to several compounds (X) mimicking amino acid side chains present in Aβ. Binding affinities were calculated as the free energy of exchange reaction replacing one water ligand in [Al(H20)6]3+ with X. The effects of hydration were studied by performing single point calculations within the Conductor Polarized Continuum Model (CPCM) at B3LYP/6- 31G(d) level of theory. Calculations in the gas phase were performed with Gaussian 98 (G 98). In our computational study, we demonstrate that the aqueous solution [Al(H2O)]3+ preferentially binds to aspartic acid residues and less to lysine and histidine residues. [ABSTRACT FROM AUTHOR]

The ternary lithium aluminum fluoride Li 3 AlF 6 is formed from two optically interesting fluorides, LiF and AlF 3 . It has been reported to have a large electronic bandgap with a reasonable lithium-ion conductivity at room temperature, making it a potential electrolyte material for solid state lithium-ion batteries. Because of complications during attempts at direct atomic layer deposition of Li 3 AlF 6 , we have studied the deposition of the material using two conversion processes. In Process 1, a conversion reaction takes place when Al(thd) 3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) and TiF 4 are sequentially pulsed onto LiF films. The Li 3 AlF 6 films contained LiF as an impurity phase, as determined with grazing incidence X-ray diffraction (GIXRD), and a large amount of titanium impurity, as determined with time-of-flight elastic recoil detection analysis (ToF-ERDA). In Process 2, AlF 3 films are exposed to Lithd vapor, resulting in a conversion reaction that produced Li 3 AlF 6 with some LiF. These films have also been studied with GIXRD and ToF-ERDA, and contained much smaller amounts of titanium and other impurities. The Li:Al metal ratios vary depending on the extent of Lithd exposure. Field emission scanning electron microscopy (FESEM) revealed that the Li 3 AlF 6 films are quite porous. [ABSTRACT FROM AUTHOR]

• B 2 O 3 -Bi 2 O 3 glass samples doped with Eu3+, Tb3+, Tm3+ ions have been successfully synthesized. • Luminescence enhancement of glass doped with AlF 3 has been observed. • Simultaneous excitation of Eu3+, Tb3+, and Tm3+ ions has been obtained with single wavelength excitation. • Proposed materials are good candidates for color-tunable phosphor applications. The B 2 O 3 -Bi 2 O 3 -AlF 3 glass system doped with Eu3+, Tb3+, Tm3+ and triply doped with Eu3+/Tm3+/Tb3+ ions in different molar ratios were successfully synthesized. Glass transition and crystallization temperatures were examined by Differential Scanning Calorimetry (DSC) measurements. X-ray Diffraction (XRD) confirmed the amorphous character of the samples. Fourier Transform Infrared Spectroscopy (FTIR) revealed that the glass matrix consists of [BO 3 ] and [BO 4 ] structural units, while X-ray Photoelectron Spectroscopy (XPS) confirmed the presence of AlF 3. An increase in luminescence spectra intensity was detected by Photoluminescence Spectroscopy (Pl), due to the presence of 10 mol% of AlF 3. The RE3+ ions embedded in the glass matrix can be simultaneously excited by a single UV light. According to the CIE results the emitted color can be tunable by varying the excitation wavelength and sample composition. The presented results confirm that the proposed glass system could be a candidate for color-tunable phosphors in LEDs. [ABSTRACT FROM AUTHOR]

Belonging to the dynamin superfamily of large GTPases, human guanylate-binding proteins ( hGBPs) comprise a family of seven isoforms ( hGBP-1 to hGBP-7) that are strongly upregulated in response to interferon-γ and other cytokines. Accordingly, several hGBPs are found to exhibit various cellular functions encompassing inhibitory effects on cell proliferation, tumor suppression as well as antiviral and antibacterial activity; however, their mechanism of action is only poorly understood. Often, cellular functions of dynamin-related proteins are closely linked to their ability to form nucleotide-dependent oligomers, a feature that also applies to hGBP-1 and hGBP-5. hGBPs are described as monomers, dimers, tetramers, and higher oligomeric species, the function of which is not clearly established. Therefore, this work focused on the oligomerization capability of hGBP-1 and hGBP-5, which are reported to assemble to homodimers and homotetramers. Employing independent methods such as size-exclusion chromatography, which relies on the hydrodynamic radius, and multiangle light scattering, which relies on the mass of the protein, revealed that previous interpretations regarding the size of the proteins and their complexes have to be revised. Additional studies using inter- and intramolecular Förster resonance energy transfer demonstrated that nucleotide-triggered intramolecular structural changes lead to a more extended shape of hGBP-1 being responsible for the appearance of larger oligomeric species. Thus, previously reported tetrameric and dimeric species of hGBP-1 and hGBP-5 were unmasked as dimers and monomers, respectively, with their shapes depending on both the bound nucleotide and the ionic strength of the solution. [ABSTRACT FROM AUTHOR]

The experimental structure of AlOF is only partially known, given the limitations of XRD measurements. We have completed an extensive first principle theoretical study of the structure of AlOF. As a complement to experimental studies we investigate the structure of AlOF with density functional theory to identify the most stable distribution of oxide and fluoride ions on the lattice. Next to the experimentally found space group Pnma, we include its subgroups in our study for a deeper understanding of the structure-stability-relation. The theoretically identified most stable structure confirms the experimentally determined space group with a homogeneous distribution of the fluoride anions. Additionally, we determine Bader charges and elastic constants for two selected distributions to gain a deeper insight into the binding of this material. [ABSTRACT FROM AUTHOR]

The isomeric structures formed by the aluminum fluoride (AlF3) system and surrounding water molecules were theoretically examined by employing MP2 and CCSD(T) methods and the aug-cc-pVDZ basis set together with the polarized continuum solvation model within a self-consistent reaction field treatment. The calculations performed for the AlF3⋅n(H2O) systems (n = 1-6) revealed that facial and meridional octahedral structures correspond to the lowest energy isomers for the AlF3⋅4H2O, AlF3⋅5H2O, and AlF3⋅6H2O systems, whereas the isomers containing the H3O+ and AlF3OH- fragments were predicted to be less stable by only 5-7 kcal/mol, which indicates the possible formation of the hydronium cations in such systems even at room temperature. [ABSTRACT FROM AUTHOR]

Nano α-aluminum fluorides with high surface area were synthesized by a simple ethylene glycol mediated sol–gel technique using dilute aq. HF as the F source, and their performances were investigated for gas-phase dehydrofluorination of 1,1,1,2-tetrafluoroethane at relatively low reaction temperature (400 °C). Aluminum precursor was crucial for the phase composition, textural and acidic properties of the resulting fluoride. Commercially low-cost and available inorganic Al was firstly used as precursor for synthesis of aluminum fluorides via the sol–gel route, and the as-prepared α-AlF 3 possessed high surface area (up to 170 m 2 g −1 ) and strong surface acidities even after thermal treatment of 400 °C. The presence of sulfate ions suppressed the crystallization of aluminum fluoride during calcination when Al 2 (SO 4 ) 3 was used as precursor, leading to an amorphous phase for as-prepared AlF 3 . Aluminum fluorides with β and pyrochlore phase were prepared using aluminum isopropoxide and aluminum diacetate hydroxide, respectively, as precursors. Based on the results of IR, XRD and element analysis, it is concluded that the formation of Al-glycolates during the sol–gel process can effectively reduce the hydrolysis of precursor and suppress particle agglomeration, thus leading to dominant formation of nano aluminum fluorides. The residual O derived from minor hydrolysis can resist sintering under high-temperature treatment, which is a key factor to improve the thermostability of as-prepared aluminum fluoride. Due to their large Lewis acidic amounts, the α-AlF 3 derived from AlOOH and Al 2 O 3 exhibited remarkably high catalytic activity with CF 3 CH 2 F conversion of 24%–28% and CF 2 =CHF selectivity above 98%, which were far higher than that of AlF 3 prepared by traditional methods. [ABSTRACT FROM AUTHOR]

Li 1.24 Ni 0.12 Co 0.12 Mn 0.56 O 2 (LNCM) with high specific capacity is a potential cathode for commercial lithium-ion batteries (LIBs). To improve the high-rate capacity and cyclic stability, LNCM sample is successfully coated by minor AlF 3 . The crystal structure and electrochemical properties of the bare and coated samples are investigated by X-ray diffractometry (XRD), scanning and transmission electron microscopy (SEM, TEM), cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT), and charge/discharge measurements. The coating layer AlF 3 efficiently plays a positive role in enhancing rate performance and cyclic stability of LNCM. At 0.5 A g −1 , the specific discharge capacity of LNCM@2%AlF 3 is 149 mAh g −1 much higher than 35 mAh g −1 in bare LNCM. At 20 mA g −1 , the specific discharge capacity of LNCM@2%AlF 3 is 223 mAh g −1 at the 60th cycle in comparison with 203 mAh g −1 in bare LNCM. Moreover, a proper AlF 3 coating layer efficiently ensures the stability of LNCM cathode operated at higher temperature. LNCM@2%AlF 3 operated at 55 °C remains 219 mAh g −1 at the 50th cycle, much higher than bare LNCM only remains 99 mAh g −1 at the 40th cycle. [ABSTRACT FROM AUTHOR]

Four differently prepared aluminum fluoride samples were tested as cathode materials for rechargeable lithium batteries. The charge-discharge results showed an initial capacity of over 900 mAh g for most of the samples at a voltage of around 2 V, giving specific energy densities of over 7405 kJ kg, higher than many commercial materials. The cycling results showed an initial high-capacity with rapid capacity fade. The reversible conversion reaction of aluminum fluoride was shown to follow the reduction of AlF into LiF and Al during discharge and upon charge Al would be oxidized to form AlF and Li again. It was found that not all the AlF would be oxidized due to the large surface/interfacial energy produced by the production of nano LiF and Al particles and the large reduction in size from the initial particles to the reduced phase. There was formation of unwanted LiAlF due to the reaction of AlF, LiF, and LiPF which also reduced the cycling capacity. Graphical Abstract: Capacity of AlF exceeds 900 mAh g. [ABSTRACT FROM AUTHOR]

Al−F bonds are among the most stable σ bonds known, exhibiting an even higher bond energy than Si−F bonds. Despite a stability advantage and a potentially high Lewis acidity of Al−F complexes, they have not been described as structurally defined catalysts for enantioselective reactions. We show that Al−F salen complexes with appended ammonium moieties give exceptional catalytic activity in asymmetric carboxycyanations. In addition to aromatic aldehydes, enal and aliphatic substrates are well accepted. Turnover numbers up to around 104 were achieved, whereas with previous catalysts 101-102 turnovers were typically attained. In contrast to Al−Me and Al−Cl salen complexes, the analogous Al−F species are remarkably stable towards air, water, and heat, and can be recovered unchanged after catalysis. They possess a considerably increased Lewis acidity as shown by DFT calculations. [ABSTRACT FROM AUTHOR]

We report on the activation of chlorinated methanes by the heterogeneous catalysts aluminum chlorofluoride (ACF) and high-surface aluminum fluoride (HS-AlF3) under moderate conditions. For comparison, chlorinated toluenes and 1,2-dichloroethane were also tested. The strong Lewis acids are able to promote the cleavage of C−Cl bonds in the presence of Et3SiH. The C−Cl bonds were converted into C−H bonds through hydrodechlorination reactions or, in the presence of benzene, into C−C bonds through Friedel-Crafts type reactions. The catalytic reactions show high conversions. [ABSTRACT FROM AUTHOR]

The article deals with the oxidation of aluminum flake particles with specific surface area ranged from 0.37 m 2 /g to 0.73 m 2 /g. The investigated powders which consisted of the above mentioned flake particles contained metal aluminum in high values (95–98 mass %). The powders possess a high hydrogen release rate (up to 27 cm 3 /min) by the interaction with calcium hydroxide water solution. The powders under study revealed a high reactivity while oxidized in a non-isothermal mode in air. The reactivity parameter values for aluminum flake particles can be compared to those of aluminum spherical nanoparticles. The application of these aluminum flake particles were possible in two directions due to their high metal content in combination with low specific surface area and high reactivity: pyrotechnics and cellular concrete production. [ABSTRACT FROM AUTHOR]

For Li-ion batteries, AlF 3 coating has been known to modify the over-lithiated layered oxide (OLO) cathodes to produce stable cathodes, but during synthesis procedure, the environment of excess amount of Li metal and free-exposed oxygen may cause the formation of Al 2 O 3 and LiF materials, separately. We investigated the possibility of separated coating formation of Al as Al 2 O 3 and F as LiF from AlF 3 using density functional theory calculation, which suggests a favorable binding affinity of both Al 2 O 3 and LiF phases to the OLO surface to support the preferable formation of coating layer of Al 2 O 3 and LiF. Meanwhile, we found the well-distributed surface modification with the coating layers and a small amount of AlF 3 (<∼11 vol%) throughout various surface analyses using the well-known coating process of AlF 3 formation. Importantly, during the coating process LiF led to the transformation of OLO surface from Li 2 MnO 3 to a self-generated structure of spinel-like LiMn 2 O 4 phase, which enhances electronic conductivity. In addition, Al 2 O 3 plays a key role in suppressing reactions between cathode and electrolyte, leading to stable cyclability. Experimental findings suggest that the well-distributed coating layer of two materials leads to a synergic effect on the enhanced electrochemical performance for high voltage operating Li-ion batteries. [ABSTRACT FROM AUTHOR]

An aluminum and fluorine enriched anodic film was fabricated on Ti 50Al by anodizing in ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF 6 ). The formation mechanism and the exact role of fluorine for the generation of this anodic film were deeply investigated. Results show that the trace amounts of residual water in the ionic liquid were responsible for the generation of oxygen contained anodic film. And the formation of this aluminum enriched structure is the result of the different solubility of titanium fluoride and aluminum fluoride during the anodization in the ionic liquid. X-ray photoelectron spectroscopy analysis shows that the aluminum fluoride can be oxidized to protective Al 2 O 3 layer at temperature higher than 300 °C. This transported Al 2 O 3 layer together with the previously formed Al 2 O 3 during anodization can efficiently inhibit the outward diffusion of Al and inward diffusion of oxygen, therefore improve the high temperature oxidation resistance of the Ti 50Al. Upon 100 h oxidation at 1000 °C, no cracks and spallation are observed on the anodized Ti 50Al. [ABSTRACT FROM AUTHOR]