Salting‐out crystallisation using NH3 in a laboratory‐scale gas lift reactor

Despite the advantages offered by gas lift reactors with respect to high gas–liquid mass transfer with a low energy input, their acceptance in the crystallisation field has been slow, especially on an industrial scale. Potassium chloride, potassium sulfate, and magnesium chloride hexammoniate (MgCl₂·6NH₃) were crystallised in a laboratory‐scale gas lift crystalliser by salting‐out using ammonia gas. Ammonia mass transfer rates were calculated for each test. To achieve maximum crystal growth, the gas rate in these reactors needs to be optimised for each crystallising system to achieve sufficient gas mass transfer as well as providing sufficient crystal slurry agitation.     

Synthesis of well‐dispersed β‐Si3N4 with equiaxed structures using carbothermal reduction–nitridation method

Well‐dispersed β‐Si₃N₄ powders with a novel equiaxed structure and eminent crystal integrity were prepared by carbothermal reduction–nitridation (CRN) strategy with the assistance of CaF₂ additive. The growth mechanism of Si₃N₄ particles in the CRN process was elucidated. It is proposed that the liquid phase formed by SiO₂ and CaF₂ additive is crucial to the formation of equiaxed β‐Si₃N₄, and with an appropriate content of CaF₂, Si₃N₄ powders with pure β phase, superior dispersity and crystal integrity can be obtained.     

Gadolinium‐conjugated FA‐PEG‐PAMAM‐COOH nanoparticles as potential tumor‐targeted circulation‐prolonged macromolecular MRI contrast agents

The aim of research is to develop potential tumor‐targeted circulation‐prolonged macromolecular magnetic resonance imaging (MRI) contrast agents without the use of low molecular gadolinium (Gd) ligands. The contrast agents were based on polymer–metal complex nanoparticles with controllable particle size to achieve the active and passive tumor‐targeted potential. In particular, poly (amidoamine) (PAMAM) dendrimer with 32 carboxylic groups was modified with folate‐conjugated poly (ethyleneglycol) amine (FA‐PEG‐NH₂, M_w: 2 k and 4 kDa). FA‐PEG‐PAMAM‐Gd macromolecular MRI contrast agents were prepared by the complex reaction between the carboxylic groups in PAMAM and GdCl₃. The structure of FA‐PEG‐PAMAM‐COOH was confirmed by nuclear magnetic resonance (¹H‐NMR), Fourier transform infrared (FTIR) spectra, and electrospray ionization mass spectra (ESI‐MS). The mass percentage content of Gd (III) in FA‐PEG‐PAMAM‐Gd was measured by inductively coupled plasma‐atomic emission spectrometer (ICP‐AES). The sizes of these nanoparticles were about 70 nm measured by transmission electron microscopy, suggestion of their passive targeting potential to tumor tissue. In comparison with clinically available small molecular Gadopentetate dimeglumine, FA‐PEG‐PAMAM‐Gd showed comparable cytotoxicity and higher relaxation rate, suggestion of their great potential as tumor‐targeted nanosized macromolecular MRI contrast agents due to the overexpressed FA receptor in human tumor cell surfaces. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Graphene‐Supported Ce–SnS2 Nanocomposite as Anode Material for Lithium‐Ion Batteries

A graphene‐supported Ce–SnS₂ (Ce–SnS₂/graphene) nanocomposite has been synthesized via a hydrothermal route. Structure, morphology, and electrochemical properties of the composites were studied by means of XRD, SEM, TEM, Raman, XPS, TGA, and electrochemical measurements. The Ce–SnS₂ crystal particles with a flower‐like structure were distributed on the graphene sheets (GNS). The particle sizes of each petal are in the range 50–100 nm with clear lattice fringes. The atomic ratio of Sn, S, Ce, C, and O is estimated to be 1:2:0.05:3.11:0.64 and the content of Ce–SnS₂ composite is 80 wt.% in the as‐synthesized sample. The Ce–SnS₂/graphene composite exhibits high initial discharge capacity (1638.3 mAh/g at 0.5 C), high capacity retention (707 mAh/g at 0.5 C after 50 cycles), and good rate capability due to the synergy effect between Ce–SnS₂ nanoparticles and graphene nanosheets. The superior performance is ascribed to the presence of graphene keeping the structure stable.     

Synthesis of tercopolymer BA–MMA–VTES and surface modification of nano‐size Si3N4 with this macromolecular coupling agent

A new macromolecular coupling agent butyl acrylate (BA)‐methyl methacrylate (MMA)‐vinyl triethoxy silane (VTES) tercopolymer was synthesized using solution polymerization initiated by free radical initiator benzoyl peroxide (BPO) and dicumyl peroxide (DCP). Dodecylthiol is choosed as the chain transfer to control the molecule weight of this tercopolymer. The terpolymer's molecular structure was confirmed by FTIR and NMR, and its average molecular weight was determined by GPC. In this work, the tercopolymer BA–MMA–VTES is used for surface modification of silicon nitride (Si₃N₄) nanopowder. The structure surface properties and thermal stability of modified nano‐Si₃N₄ were systematically investigated by FTIR, TGA, TEM, and size distribution analyzer. The results show that the macromolecular coupling agent bonds covalently on the surface of nano‐sized Si₃N₄ particles and an organic coating layer is formed. The optimum loading of this macromolecular coupling agent BA–MMA–VTES tercopolymer is 5% (wt %) of nano‐sized Si₃N₄. TEM also reveals that modified nano‐Si₃N₄ possesses good dispersibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polyoxovanadate‐Based Metal−Organic Octahedron Based on 1,4‐Naphthalenedicarboxylic Acid

A new polyoxovanadate‐based metal?organic octahedron (VMOP‐26) was synthesized from vanadium acetylacetonate and 1,4‐naphthalenedicarboxylic acid (1,4‐H₂NDC) under solvothermal condition and characterized by single crystal X‐ray diffraction, powder X‐ray diffraction, infrared spectroscopy and thermogravimetric analysis. The structure of VMOP‐26 was composed of six {V₅O₉Cl} clusters and twelve 1,4‐NDC ligands with regular octahedral geometry in which the polyoxovanadate clusters act as vertices and 1,4‐NDC as edges. Each octahedron was surrounded by twelve adjacent octahedra with edge‐to‐edge connection modes. The absorption ability toward the dye molecules of VMOP‐26 was investigated because VMOP‐26 was an anionic cage. The results exhibit that only cationic dyes (Methylene blue (MB⁺), crystal violet (CV⁺), Rhodamine B (RhB⁺)) can be absorbed into the crystal lattice of VMOP‐26, which indicates that the cationic dye absorption is an ion‐exchange process. Besides, the fluorescent property of VMOP‐26 was also investigated.     

Structures and Properties Prediction of HMX/TATB Co‐Crystal

In this study, a new co‐crystal explosive of 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX)/1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) (molar ratio 1 : 1) was designed based on crystal engineering. The crystal structure was predicted using the polymorph predictor (PP) method. The main properties of co‐crystal consisting of mechanical properties, stability, and interaction formats were simulated through molecular dynamics methods. Simulated results indicate that the crystal structure of the HMX/TATB co‐crystal may belong to the P , P2₁2₁2₁ or P2₁/c space group. The calculations of the binding energy and the analysis for radial distribution function show that the two components are connected through electrostatic hydrogen bonding and strong van der Waals interactions. The new co‐crystal has better mechanical properties with the moduli systematically decreased. With the appearance of the new crystal, the trigger bond N NO₂ has little change.     

Defining a strain‐induced time constant for oriented low shear‐induced structuring in high consistency MFC/NFC‐filler composite suspensions

Micro and nanofibrillated cellulose is an essentially one‐dimensional high aspect‐ratio particle material, which can undergo two‐dimensional layer (band) structuring under shear. Controlling the evolving rheological properties in aqueous suspension is essential for industrial applications in composite materials. This study focuses on an as yet considered to be unreported phenomenon of structure hardening under low shear. The timescale of the quasi gelation‐controlled structure formation under low shear is studied using the large gap vane‐in‐cup geometry of the Brookfield viscometer. It is proposed that localized structure forms within continuous shear bands, similar to quasi liquid‐crystal formation. By extrapolating a characteristic structure growth parameter to the rotation speed at which it becomes zero, the strain‐induced structure time constant, t_gel, can be obtained as (= f (Ω)) = 1/t_gel for the range Ω = 10–100/min. The time constant of low shear structure formation is shown to be separable from the static viscoelastic structure build under oscillation in concentrated composite suspension using plate‐plate geometry, which is manifest by a Weissenberg normal force response on switching to applied shear, when the time constant of structuration t_gel is long. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42827.     

Effect of Gd Content on Luminescence Properties of Eu3+‐Doped La2−xGdxZr2O7 Transparent Ceramics

3 at.% Eu³⁺‐doped La_2?xGd_xZr₂O₇ (x = 0–2.0) transparent ceramics were fabricated by vacuum sintering. The effect of Gd content on crystal structure, in‐line transmittance, and luminescence property of the ceramics were investigated. The ceramics are all cubic pyrochlore structure with high transparency. The cut‐off edge of the transmittance curve of the ceramics varied with Gd content and was also affected by the annealing process. The luminescence intensity became stronger for the ceramics annealed in air. As Gd content increased, the energy band structure as well as the luminescence behavior of the ceramics was changed; in addition, the symmetry of the crystal lattice reduced, resulting in the shift of the strongest luminescence peak from 585 nm to around 630 nm.     

Chemical Expansion Due to Hydration of Proton‐Conducting Perovskite Oxide Ceramics

The crystal structures of proton‐conducting BaZr_1?xY_xO_3?x/2 (BZY05–BZY20) and BaCe_0.8Y_0.2O_2.9 (BCY20) during hydration/dehydration has been studied by in situ high‐temperature X‐ray diffraction and thermal analysis. A contraction/expansion of the crystal lattice associated with dehydration/hydration was observed for all materials at elevated temperatures and the polymorphic phase transition temperatures of BaCe_0.8Y_0.2O_2.9 were depressed by lowering the vapor pressure of water. A thermodynamic formalism is introduced to describe the chemical expansion associated with the hydration of oxygen vacancies in acceptor‐doped oxides. A conventional point defect model was applied to describe the lattice strain associated with the hydration. The chemical expansion is discussed with respect to the available volumetric data on the hydration of proton‐conducting oxide materials and its likely impact on ceramic fuel cells/hydrogen separation membranes utilizing a proton‐conducting electrolyte.     

Temperature‐ and E‐field‐dependent domain configuration and electrical properties in (K,Na, Li)(Nb,Ta, Sb)O3 single crystal

E‐field‐ and temperature‐dependent domain evolution of lead‐free tetragonal (K, Na, Li)(Nb, Sb, Ta)O₃ (KNLNTS) single crystals as well as its corresponding electrical properties have been investigated. When E field is applied along [011]_C direction, (2T) engineered domain structure is formed. Spontaneous polarizations switch under a critical electric field (around 4‐5 kV/cm), resulting in significant changes in domain structure and great improvement in piezoelectric properties. Furthermore, it is found that piezoelectric constant d₃₁ and electromechanical coupling factor k₃₁ of [011]_C poled KNLNTS single crystal decrease with temperature. The extrinsic and intrinsic piezoelectric responses are discussed from the viewpoint of domain structure and lattice distortion, respectively. Our results show that the nanodomain structure relaxes and the lattice distortion declines with temperature, resulting in reduction of extrinsic and intrinsic piezoelectric responses, respectively. Therefore, the piezoelectric instability is ascribed to the decrease of both extrinsic and intrinsic contributions. This work provides a better understanding of domain engineering technique, and the useful information on the improvement of both piezoelectricity and temperature stability of the lead‐free piezoelectric materials.     

Bicyclic Derivatives of the Potent Dual Aromatase–Steroid Sulfatase Inhibitor 2‐Bromo‐4‐{[(4‐cyanophenyl)(4H‐1,2,4‐triazol‐4‐yl)amino]methyl}phenylsulfamate: Synthesis,SAR, Crystal Structure,and in vitro and in vivo Activities

The design and synthesis of a series of bicyclic ring containing dual aromatase–sulfatase inhibitors (DASIs) based on the aromatase inhibitor (AI) 4‐[(4‐bromobenzyl)(4H‐1,2,4‐triazol‐4‐yl)amino]benzonitrile are reported. Biological evaluation with JEG‐3 cells revealed structure–activity relationships. The X‐ray crystal structure of sulfamate 23 was determined, and selected compounds were docked into the aromatase and steroid sulfatase (STS) crystal structures. In the sulfamate‐containing series, compounds containing a naphthalene ring are both the most potent AI ( 39 , IC_{50 AROM}=0.25 nM ) and the best STS inhibitor ( 31 , IC_{50 STS}=26 nM ). The most promising DASI is 39 (IC_{50 AROM}=0.25 nM , IC_{50 STS}=205 nM ), and this was evaluated orally in vivo at 10 mg kg^?1, showing potent inhibition of aromatase (93 %) and STS (93 %) after 3 h. Potent aromatase and STS inhibition can thus be achieved with a DASI containing a bicyclic ring system; development of such a DASI could provide an attractive new option for the treatment of hormone‐dependent breast cancer.     

Enhanced thermal stability of (NaCe)‐multidoped CaBi2Nb2O9 by A‐site vacancies‐induced pseudo‐tetragonal distortion

Although A‐site codoping of alkali metal and rare‐earth elements are known to effectively promote the d₃₃ of CaBi₂Nb₂O₉ (CBN), its thermal depoling behavior cannot be well promised. In this work, piezoelectricity of CBN was effectively promoted by (NaCe) modification, and its thermal instability was caused by the lattice evolution from orthorhombic structure to pseudo‐tetragonal structure during thermal depoling process. A‐site vacancies could induce pseudo‐tetragonal distortion in Ca_0.92(Na_0.5Ce_0.5)_0.08Bi₂Nb₂O₉ ceramic, which obviously enhanced the thermal stability of lattice by reducing the rotation of the Nb–O octahedron during the thermal depoling process, as compared with orthorhombic structure, thereby weakening the swing of spontaneous polarization (P_s) and promoting the thermal depoling performance. Consequently, good thermal stability was obtained (remained 92% of initial d₃₃ after depoling at 600°C). Moreover, dominant role of oxygen vacancies in the electrical conduction and relaxation process promised that the introduction of small amount of A‐site vacancies would not influence the electrical properties obviously.     

First‐Principles Insight into the Composition‐Dependent Structure and Properties of γ‐Alon

Spinel type Aluminum oxynitride (γ‐alon) solid solution exists in the Al₂O₃‐rich region of AlN–Al₂O₃ systems. The first‐principles calculations facilitate our investigations on composition‐dependence of structure and properties in γ‐alon without the limit of experimental solubility. The constant anion crystal structure of γ‐alon was described as the solid solution of spinel phase γ‐Al₂O₃ and the ideal Al₃O₃N with formula of Al_(8+x)/3O_4?xN_x (0 ≤ x ≤ 1). The unit cell expands with increasing Al₃O₃N composition. The lattice parameter increases nonlinearly with the composition of Al₃O₃N, which deviates from Vegard's law. As x increases, the anions dilate from the Al^IV along (1 1 1) direction, and two new narrow peaks (approximate –12.7 and –0.3 eV) become stronger and the conduction band presents a downward shift to low energy in the TDOS. The absorption edge in the UV region of ε₂(ω) present slight red‐shift of 0.5 eV as x increases. Because the compressibility was improved by expansion of coordination polyhedron, the elastic properties were just slightly enhanced as the nitrogen concentration increases. It is suggested that the notable enhancement of mechanical properties in γ‐alon may be difficult to yield by varying the content of substituted nitrogen atoms. The calculated results provide the basis for understanding the crystal structure and intrinsic properties of γ‐alon with different compositions.     

Free‐radical grafting of trans‐ethylene‐1,2‐dicarboxylic acid onto molten ethylene‐vinyl acetate copolymer

Distinctive features of free‐radical grafting of trans‐ethylene‐1,2‐dicarboxylic acid (TEDA) onto macromolecules of molten ethylene‐vinyl acetate copolymer (EVA) in the course of reactive extrusion have been investigated along with structure, mechanical characteristics, and high‐elastic properties of molten functionalized products (EVA‐g‐TEDA). It is shown that EVA‐g‐TEDA yield depends on both the peroxide initiator concentration and content of vinyl acetate units in the copolymer molecular structure. At functionalization, acid grafting is accompanied by secondary reactions of macromolecular degradation and crosslinking. With a low‐peroxide initiator concentration (0.1 wt %), degradation prevails; with a higher (0.3 wt %) concentration, crosslinking of macromolecules prevails. It is reported that monomers being grafted attach mostly over secondary carbon atoms in the polymer chain. EVA‐g‐TEDA appears to have a less perfect crystal structure with a lower‐melting temperature and crystallinity as against the starting polymer. The functionalized products display enhanced rigidity and lower deformability in comparison with the initial copolymer. Variations in the swelling ratio and melt strength of EVA‐g‐TEDA depend on the course of competing secondary processes of macromolecular degradation and crosslinking. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Magnetic behavior of polycarbosilazane ?FeII, ?FeIII and mixed‐valence ?FeII–III chloride metallopolymers

Fe^II, Fe^III and mixed‐valence Fe^II–III chlorides were reacted with poly[N,N′‐bis(dimethylsilyl)ethylenedi‐ amine], [? Si(CH₃)₂NHCH₂CH₂NH? ]_n, to form the corresponding Fe‐polycarbosilazane macromolecular complexes. The average chain–chain spacing in these materials was estimated from X‐ray diffraction data and found to be 6.94, 7.29, 7.30 and 7.45 Å in metal‐free and Fe^II? , Fe^III? and Fe^II–III‐containing polycarbosilazanes, respectively. This demonstrates that Fe^II, Fe^III and Fe^II–III chlorides are encapsulated between the polycarbosilazane chains. The chain–chain expansions in the divalent Fe^II and trivalent Fe^III chloride macromolecular complexes are comparable, but less than that in the Fe^II–III chloride analog, which suggests that different chain–chain packings exist in the mixed‐valence macromolecular complex. The magnetic properties of the resulting complexes were investigated by measuring the magnetization in magnetic fields up to 8 kOe and in the temperature range from liquid nitrogen temperature to room temperature. Copyright © 2007 Society of Chemical Industry     

Surface modification of nano‐sized silicon nitride with BA‐MAA‐AN tercopolymer

In this work, a macromolecular coupling agent (BA‐MAA‐AN tercopolymer) was used for surface modification of native nano‐sized silicon nitride (Si₃N₄) powder. This modification strategy was designed for preparing nano‐Si₃N₄/NBR composites. The structure and surface properties of modified nano‐Si₃N₄ were systematically investigated by FTIR, XPS, TGA, TEM, Size Distributions Analyzer, and Contact Angle Measurement. It was found that, the optimum loading of BA‐MAA‐AN tercopolymer coated on the surface of nano‐sized Si₃N₄ is 10% of nano‐Si₃N₄. According to the spectra of FTIR, XPS and TGA, it can be inferred that this macromolecular coupling agent covalently bonds on the surface of nano‐sized Si₃N₄ particles and an organic coating layer is formed. The contact angle experiments show that the hydrophobic property of nano‐sized Si₃N₄ modified with macromolecular coupling agent is improved obviously. TEM reveals that modified nano‐Si₃N₄ possesses good dispersibility and the average diameter in NBR is less than 100 nm. It has also been found that the oil resistance of NBR based nanocomposites is improved greatly due to the modified nano‐Si₃N₄. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structure–property relationship of polyethylene glycol‐based PU/PAN semi‐interpenetrating polymer networks

Polyethylene glycol‐400 (PEG) based polyurethane (PU) and polyacrylonitrile (PAN) semi‐interpenetrating polymer networks (SIPNs) (PU/PAN; 90/10, 70/30, 60/40, and 50/50) have been prepared by sequential polymerization method. The prepared SIPNs have been characterized by physicomechanical properties. The microcrystalline parameters such as crystal size (〈N〉), lattice disorder (g), surface (D_s) and volume (D_v) weighted crystal size of SIPNs have been estimated using wide angle X‐ray scattering studies, and quantification of the polymer network has been carried out on the basis of these parameters. The microstructural parameters have been established using Exponential, Lognormal, and Reinhold asymmetric column length distribution functions and the results are compiled. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 177–187, 2006     

Preparation and structural characterization of water‐soluble O‐hydroxypropyl chitin derivatives

Water‐soluble hydroxypropyl chitin (HPC) derivatives were prepared by the reaction of chitin with propylene oxide in homogeneous conditions using a dimethylacetamide/5% lithium chloride solvent system. The reaction conditions for a proper substitution of the hydroxypropyl group were an 80°C reaction temperature, 24‐h reaction time, and 48‐h aging time. ¹H‐NMR and ¹³C‐cross‐polarization/magic angle spinning NMR spectroscopy were used for determining the substitution value and reaction site of substitution. It was found that the substitution reaction occurred mainly at the C₆? OH group in the chitin molecules and water‐soluble chitin derivatives could be obtained at a substitution value higher than 0.35, which is known as a critical substitution value. X‐ray diffraction analysis and FTIR spectroscopy showed that the structural characteristics of HPC derivatives were dependent on the substitution value. As the substitution value of the HPC derivative increased the α‐chitin crystal structure changed to the water‐soluble β‐chitin form in higher substitution values. Differences in the interchenic hydrogen bonding, interplanar spacing of the crystal lattice plane, and crystallinity can explain the structural changes upon substitution. The thermal decomposition temperature was also related to the characteristics of the crystalline structure, depending on a critical substitution value. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2624–2632, 2001     

Synthesis of star polymer poly(ethylene glycol)3–poly(N,N‐dimethyl acrylamide) and its application in protein resistance and separation

A star polymer composed of three poly(ethylene glycol) (PEG) arms and one poly(N,N‐dimethyl acrylamide) (PDMA) arm (PEG₃–PDMA) was synthesized by amidation and atom‐transfer radical polymerization. The structure of PEG₃–PDMA was confirmed by ¹H‐NMR and gel permeation chromatography results. The surface adsorption and protein‐resistance behaviors of the star polymer PEG₃–PDMA, diblock copolymer PEG–PDMA, and homopolymer PEG were investigated by a quartz crystal microbalance with dissipation. The results indicate that the PEG₃–PDMA coating could reduce protein adsorption to 13% at least, more effectively than the PEG–PDMA coating; this indicated that the protein‐resistance properties depended on the PEG chain density and surface coverage. If PEG₃–PDMA were to be used as the physical coating in capillary zone electrophoresis, it could yield a well‐suppressed eletroosmotic flow with greater stability and separate proteins with a lower relative standard deviration (RSD) of protein migration time and a higher separation efficiency than a bare fused‐silica capillary in a broad pH range. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013