Hexachloroplatinate(IV) anion-induced cucurbit[5]uril and cucurbit[8]uril supramolecular assemblies with linear channels

Two Q[n]-based porous compounds, Q[5]·[PtCl₆]^2 −·2H₃O·12H₂O and 2Q[8]·[PtCl₆]^2 −·2H₃O·74H₂O in cooperating the hexachloroplatinate(IV) anion ([PtCl₆]^2 −) as an inorganic structure directing agent are demonstrated. The driving forces for the formation of such novel Q[n]-based porous compounds are considered to be the outer surface interactions of Q[n]s, including dipole interactions between Q[n]s and ion-dipole interactions between [PtCl₆]^2 − anions and Q[n]s. Moreover, the Q[5]-based porous compound displays absorption distinctness for tetrachloromethane, whereas the Q[8]-based porous compound displays absorption distinctness for methanol.     

Adsorption Behavior of Rhodamine B on UiO-66

The adsorption characteristics of UiO-66 (a Zr-containing metal–organic framework formed by terephthalate) for Rhodamine B (RhB), such as isotherms, kinetics and thermodynamics, were investigated systematically. The batch adsorption data conform well to the Langmuir and Freundlich isotherms. The adsorption kinetics of UiO-66 for RhB can be well described by the pseudo first-order model, and the adsorption thermodynamic parameters ΔG₀, ΔH₀ and ΔS₀ at 273 K are − 6.282 kJ·mol^− 1, 15.096 kJ·mol^− 1 and 78.052 J·mol^− 1·K^− 1, respectively. The thermodynamic analyses show that the adsorption process of RhB on UiO-66 is more favorable at higher temperatures. UiO-66 can be regenerated by desorbing in DMF solution with ultrasonic for 1 h. UiO-66 can keep good performance for at least six cycles of sorption/desorption.     

Enhancement of Lipase-catalyzed Synthesis of Caffeic Acid Phenethyl Ester in Ionic Liquid with DMSO Co-solvent

Caffeic acid phenethyl ester (CAPE) is a natural and rare ingredient with several biological activities, but its industrial production using lipase-catalyzed esterification of caffeic acid (CA) and 2-phenylethanol (PE) in ionic liquids (ILs) is hindered by low substrate concentrations and long reaction time. To set up a high-efficiency bioprocess for production of CAPE, a novel dimethyl sulfoxide (DMSO)–IL co-solvent system was established in this study. The 2% (by volume) DMSO–[Bmim][Tf₂N] system was found to be the best medium with higher substrate solubility and conversion of CA. Under the optimum conditions, the substrate concentration of CA was raised 8-fold, the reaction time was reduced by half, and the conversion reached 96.23%. The kinetics follows a ping-pong bi-bi mechanism with inhibition by PE, with kinetic parameters as follows: V_max = 0.89 mmol · min^− 1 · g^− 1, K_m,CA = 42.9 mmol · L^− 1, K_m,PE = 165.7 mmol · L^− 1, and K_i,PE = 146.2 mmol · L^− 1. The results suggest that the DMSO co-solvent effect has great potential to enhance the enzymatic synthesis efficiency of CAPE in ILs.     

Study on pesticide activities of four ligands and their transition metal complexes with 8-mercaptoquinoline and pyridine terminal groups

Four kinds of thioether ligands (Q1–Q4) and their 21 kinds of transitional metal complexes have been synthesized, in which two new complexes have been prepared and tested. Some potential laws were obtained by comparing the pesticide activities of four kinds of ligands and their 21 kinds of transitional metal complexes based on the difference of metal ions, anions and spatial structures. The results revealed that the complexes with Ag⁺ ion had very outstanding pesticide activities which might be related to the structure unit of a bimetallic ring and the bacteriostatic effects of anions decreased in the order Cl⁻ > BF₄⁻ > ClO₄⁻ = CF₃CO₂⁻ > CF₃SO₃⁻ > NO₃⁻. Compared with ligands Q1–Q4, the inhibitory effect of ligand Q1 was the best, which might be connected to the stable spatial structure.     

Diamond based field-effect transistors with SiNx and ZrO2 double dielectric layers

A diamond-based field-effect transistor (FET) with SiN_x and ZrO₂ double dielectric layer has been demonstrated. The SiN_x and ZrO₂ gate dielectric are deposited by plasma-enhanced chemical vapor deposition (PECVD) and radio frequency (RF) sputter methods, respectively. SiN_x layer is found to have the ability to preserve the conduction channel at the surface of hydrogen-terminated diamond film. The leakage current density (J) of SiN_x/ZrO₂ diamond metal-insulator-semiconductor FET (MISFET) keeps lower than 3.88 × 10^− 5 A·cm^− 2 when the gate bias was changed from 2 V to − 8 V. The double dielectric layer FET operates in a p-type depletion mode, whose maximum drain-source current, threshold voltage, maximum transconductance, effective mobility and sheet hole density are determined to be − 28.5 mA·mm^− 1, 2.2 V, 4.53 mS·mm^− 1, 38.9 cm²·V^− 1·s^− 1, and 2.14 × 10¹³ cm^− 2, respectively.     

Biocatalytic synthesis of short-chain flavor esters with high substrate loading by a whole-cell lipase from Aspergillus oryzae

A lipase from Aspergillus oryzae WZ007 exhibited high esterification activities toward a series of short-chain acids and alcohols. Moreover, it displayed a strong tolerance for high substrate concentration of up to 2.0 M and presented a highest initial rate of 276 mmol·L^− 1·h^− 1 at this concentration. After a reaction time of 48 h, the conversion rates of acids were higher than 80% for the synthesis of a majority of heptanoic acid esters, some octanoic acid esters and n-propyl hexanoate. These results implied that A. oryzae WZ007 lipase was a promising biocatalyst in the production of flavor esters.     

Separation and determination of cadmium in water by foam column prior to inductively coupled plasma optical emission spectrometry

The sorption profile of cadmium (II) ions from aqueous iodide media onto procaine hydrochloride (PQ⁺·Cl⁻) treated polyurethane foams (PUFs) solid sorbent was studied. PQ⁺·Cl⁻ treated PUFs solid sorbent was found suitable and fast for Cd²⁺ uptake as [CdI4]_aq²⁻. Thus, removal of Cd²⁺ at trace levels by the sorbent packed columns was achieved. The sorbed Cd²⁺ species onto packed column were recovered with HNO₃ (10.0 mL, 1.0 mol L⁻¹) prior determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). Plot of Cd²⁺ ions concentration was linear in the range 0.05–15 μg L⁻¹. The limits of detection and quantification of Cd²⁺ were found 0.01 μg L⁻¹ and 0.033 μg L⁻¹, respectively. Such limits could be improved to lower values by retention of Cd²⁺ species from large sample volumes of the aqueous phase at the optimized conditions. The relative standard deviation of the packed column for the extraction and recovery of standard aqueous solutions (0.1 L) containing 1.0 and 5.0 μg L⁻¹ (n = 3) of Cd²⁺ ions at flow rate of 5.0 mL min⁻¹ were 1.98 and 2.9%, respectively. The method was validated by analysis of Cd in certified reference materials (CRMs) IAEA-Soil-7 and TMDW water and wastewater samples.     

Electrooxidation of p-nitrophenol on organobentonite modified electrodes

A natural bentonite, modified with different quaternary ammonium cations, hexadecyl trimethylammonium, (HDTMA), dodecyl trimethylammonium (DTMA) and tetramethylammonium (TMA), was used as an electrode material in a p-nitrophenol (p-NP) electrooxidation. On the basis of electrochemical response, TMA-modified bentonite (TMA-B) electrode was chosen for further investigations. The influence of TMA loading on the electrochemical properties of the TMA-B electrodes toward p-NP electrooxidation was examined. Electrode sensitivity toward p-NP was performed. The detection limit for p-NP of 1 · 10^− 6 mol dm^− 3 was obtained.     

Ionothermal synthesis,fluorescence, and DFT calculation of three lanthanide-based metal-organic frameworks

Three lanthanide-based metal-organic frameworks (MOFs), [Ln(SIP)(HSIP)][EMIm]₂, (Ln = La(1), Nd(2) Eu(3); H₂SIP = 5-sulfoisophthalic acid; EMImBr = 1-ethyl-3-methyl-imidazole bromine), were obtained under the ionic liquid medium. Crystal structure analysis reveals that there are two-dimensional metal-organic frameworks, which are built from the connection of {Ln_n} chains by SIP^3 − ligands. It is found that EMIm⁺ cations are filled in the void between 2D layers. Interestingly, the whole framework shows one new topology with the symbol of [3 · 4²]₂[3⁴ · 4⁶ · 5⁶ · 6⁸ · 7³ · 8]. Luminescence measurement exhibits that compound 3 has good emission property. Furthermore, DFT calculation results confirm that the emission mechanism can be attributed to the transition of f–f transition of Eu(III) ions, where SIP^3 − ligand acts as the role of electron carrier.     

Measuring the anisotropic thermal diffusivity of silicon nitride grains by thermoreflectance microscopy

High-resolution thermoreflectance microscopy measurements were performed at five frequencies on rod-shaped Si₃N₄ grains in a ceramic. Our heat diffusion model takes account of the coating and of a coating/substrate resistance. The parameters are adjusted to fit the measurements at the five frequencies simultaneously. The principal diffusivities obtained in individual grains are 0·32 cm² s⁻¹ along the a-axis, and 0·84 cm² s⁻¹ along the c-axis (corresponding conductivities: 69 and 180 W m⁻¹ K⁻¹). The thermal anisotropy inside individual Si₃N₄ grains is found to be intrinsic, without direct connection with their elongated shape. ‘Macroscopic’ diffusivities, obtained by mirage effect, are different from the values measured inside individual grains, as a consequence of the dispersion of the grains' orientations in the ceramic and of a second-phase effect.     

Kinetic and thermodynamic studies on the removal of Cu(II) ions from aqueous solutions by adsorption on modified sand

Studies on the removal of copper by adsorption on modified sand have been investigated. The adsorbent was characterized by XRD, FTIR and SEM. Removal of Cu was carried out in batch mode. The values of thermodynamic parameters namely ΔG⁰, ΔH⁰ and ΔS⁰ at 25 °C were found to be −0.230 kcal⁻¹ mol⁻¹, +4.73 kcal⁻¹ mol⁻¹ and +16.646 cal K⁻¹ mol⁻¹, respectively. The process of removal was governed by pseudo second order rate equation and value of k₂ was found to be 0.122 g mg⁻¹ min⁻¹ at 25 °C. The resultant data can serve as baseline data for designing treatment plants at industrial scale.     

Half-metallocene zirconium complex bearing tridentate [N,N,O] ligand and its use in homo- and copolymerization of ethylene

The novel half-metallocene zirconium (IV) bearing quinoline-amino-phenolate tridentate ligand (Zr1) was synthesized and characterized by elemental analysis, NMR spectroscopy, and X-ray crystallography. The complex Zr1, upon activation with MAO, proved active in the polymerization of ethylene (26-2015 kg of PE/mol[Zr]·h^− 1), yielding high-density polyethylenes with molecular weight varying from 129 to 364 × 10³ g·mol^− 1. Complex Zr1 was also tested in the copolymerization of ethylene with 1-hexene affording high molecular weight poly(ethylene-co-1-hexene) with low comonomer incorporation (1.0–1.9%).     

An artificial photosynthesis system based on CeO2 as light harvester and N-doped graphene Cu(II) complex as artificial metalloenzyme for CO2 reduction to methanol fuel

An artificial photosynthesis catalyst composed of CeO₂, N-doped graphene and copper ions (CeO₂–NG–Cu^2 +) was fabricated. The light-harvesting CeO₂–NG was characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic reduction of CO₂ was conducted in an aqueous solution of Na₂SO₃. Results indicated that the reduction rate of CO₂ to methanol approached 507.3 μmol · g⁻¹ cat. · h^− 1 for CeO₂–NG–Cu^2 + artificial photosynthesis system in 80 min, whereas the reduction rate was only 5.8 μmol · g⁻¹ cat. · h^− 1 for bare CeO₂–NG without metalloenzyme. Therefore, artificial metalloenzyme played a vital role in reducing CO₂ to methanol fuel.     

Leaching kinetics of ulexite in sodium hydrogen sulphate solutions

The aim of this study was to investigate the dissolution kinetics of ulexite in sodium hydrogen sulphate solutions in a mechanical agitation system and to declare an alternative reactant to produce boric acid. Reaction temperature, concentration of sodium hydrogen sulphate solutions, stirring speed, solid/liquid ratio and ulexite particle size were selected as parameters of the dissolution rate of ulexite. The experimental results were successfully correlated by linear regression using Statistica program. Dissolution curves were evaluated in order to test shrinking core models for solid-fluid systems. It was observed that increase in the reaction temperature and decrease in the solid/liquid ratio cause an increase in the dissolution rate of ulexite. The dissolution extent is highly increased with increase in the stirring speed rate between 100 and 700 rpm experimental conditions. The activation energy was found to be 36.4 kJ/mol. The leaching of ulexite was controlled by diffusion through the ash or product layer. The rate expression associated with the dissolution rate of ulexite depending on the parameters chosen may be summarized as: 1–3(1 − X)^2/3 + 2(1 − X) = 6.17 × C^0.97 × W^1.17 × D^−1.72 × (S/L)^−0.66 × e^(−36.4/RT)·t.     

Characterization of vertical Mo/diamond Schottky barrier diode from non-ideal I–V and C–V measurements based on MIS model

In this study, we investigated non-ideal characteristics of a diamond Schottky barrier diode with Molybdenum (Mo) Schottky metal fabricated by Microwave Plasma Chemical Vapour Deposition (MPCVD) technique. Extraction from forward bias I–V and reverse bias C^− 2–V measurements yields ideality factor of 1.3, Schottky barrier height of 1.872 eV, and on-resistance of 32.63 mΩ·cm². The deviation of extracted Schottky barrier height from an ideal value of 2.24 eV (considering Mo workfunction of 4.53 eV) indicates Fermi level pinning at the interface. We attributed such non-ideal behavior to the existence of thin interfacial layer and interface states between metal and diamond which forms Metal-Interfacial layer-Semiconductor (MIS) structure. Oxygen surface treatment during fabrication process might have induced them. From forward bias C–V characteristics, the minimum thickness of the interfacial layer is approximately 0.248 nm. Energy distribution profile of the interface state density is then evaluated from the forward bias I–V characteristics based on the MIS model. The interface state density is found to be uniformly distributed with values around 10¹³ eV^− 1·cm^− 2.     

Photocatalytic degradation of 17-β-oestradiol on immobilised TiO2

Micro-molar concentrations of aqueous 17-β-oestradiol were 98% destroyed in 3.5 h by photocatalysis over the titanium dioxide powder immobilised on Ti-6Al-4V alloy. The concentration of oestradiol was determined by HPLC with fluorescence detection. The degradation kinetics were fitted to a Langmuir–Hinshelwood model with k(S) = 4.4 × 10⁻² μmol dm⁻³ min⁻¹ and K(S) = 0.347 dm³ μmol⁻¹. The pseudo-first-order rate constant (1.57 × 10⁻² min⁻¹) was in line with the 50% degradation time of 40 min. The apparent quantum yield per electron was φ_e′  = 0.41%. The effect of pH on the initial rate of degradation was similar to that reported for phenol.     

Dense carbon monoliths for supercapacitors with outstanding volumetric capacitances

A commercially available dense carbon monolith (CM) and four carbon monoliths obtained from it have been studied as electrochemical capacitor electrodes in a two-electrode cell. CM has: (i) very high density (1.17 g cm⁻³), (ii) high electrical conductivity (9.3 S cm⁻¹), (iii) well-compacted and interconnected carbon spheres, (iv) homogeneous microporous structure and (v) apparent BET surface area of 957 m²g⁻¹. It presents interesting electrochemical behaviors (e.g., excellent gravimetric capacitance and outstanding volumetric capacitance). The textural characteristics of CM (porosity and surface chemistry) have been modified by means of different treatments. The electrochemical performances of the starting and treated monoliths have been analyzed as a function of their porous textures and surface chemistry, both on gravimetric and volumetric basis. The monoliths present high specific and volumetric capacitances (292 F g⁻¹ and 342 F cm⁻³), high energy densities (38 Wh kg⁻¹ and 44 Wh L⁻¹), and high power densities (176 W kg⁻¹ and 183 W L⁻¹). The specific and volumetric capacitances, especially the volumetric capacitance, are the highest ever reported for carbon monoliths. The high values are achieved due to a suitable combination of density, electrical conductivity, porosity and oxygen surface content.     

Reversible water inclusion in a porous magnetic material synthesized from copper(II) incorporated metal-organic framework showing alternate ferro- and antiferromagnetic interactions

X-ray structural analysis shows that {[Cu₂(CTA) (H₂O)] · 5 H₂O}_n constitutes infinite one-dimensional parallel chains along the c-axis with water columns running down the crystallographic a-axis. The inclusion of water molecules is reversible and is confirmed by X-ray powder diffraction studies. The magnetic data (2–300 K) reveal that there are alternate ferro- (J = 0.29 cm⁻¹) and antiferromagnetic (J = −2.5 cm⁻¹) interactions.     

Controlled release of drug molecules in metal–organic framework material HKUST-1

The Cu₃(BTC)₂ metal–organic framework (MOF) (BTC = 1,3,5-benzenetricarboxylate), also known as HKUST-1, is one of the earliest reported stable MOFs with a very high surface area. In this study, HKUST-1 was used for the first time to absorb the pharmaceutical products of ibuprofen, anethole and guaiacol with loading amount of 0.34 g·g^− 1, 0.38 g·g^− 1 and 0.40 g·g^− 1, respectively, which also showing good controlled drug release property. The result from this work provides a new attempt for HKUST-1 to be used as potential platform for drug delivery and release.     

A facile synthesis of CuO nanowires and nanorods,and their catalytic activity in the oxidative degradation of Rhodamine B with hydrogen peroxide

In this study, a new and facile solution-phase route to prepare CuO nanowires and nanorods with the assistance of salicylic acid was reported. Compared with the commercial CuO nanoparticles, both the CuO nanowires and nanorods exhibited significantly improved catalytic activity in the degradation of Rhodamine B with H₂O₂, which may result from their special one dimensional nanostructures. The apparent activation energy of Rhodamine B oxidation with H₂O₂ in the presence of the CuO nanowires and nanorods was 30.95 kJ·mol^− 1 and 32.07 kJ·mol^− 1, respectively, which was much lower than that in the absence of catalysts.