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2014, 57 No. 12 pp. 1603-1780
Published: 27 November 2014

The emergence of multi-drug-resistant pathogenic bacteria strains has threatened the global public health. The cover picture presents a new method to screen antibiotic combinations, which takes advantage of the logic-signal output of genetically engineered drug-resistant E. coli strains expressing different fluorescent proteins. Chloramphenicol and cefotaxime taken as antibiotic combination example were added to the system of the constructed kanamycin-resistant E. coli expressing GFP and ampicillin-resistant E. coli expressing td Tomato fluorescent protein as dual-drug resistant model bacteria. By monitoring the complex logic-signal output patterns of GFP and td Tomato fluorescent proteins, the effective antibiotic combinations were identified in a simple and quantitative manner (See the article by LV FengTing, LIU LiBing & WANG Shu on page 1696–1702).

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XinSheng Zhao, Shu Wang, Fang Huang
2014 Vol. 57 (12): 1603-1604 [Abstract] ( 88 ) [ PDF (576 KB)   ] ( 65 )  [Supporting InformationDOI: 10.1007/s11426-014-5261-1
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DNA G-quadruplex and its potential as anticancer drug target Hot!
ONEL Buket, LIN Clement, YANG DanZhou

G-quadruplex secondary structures are four-stranded globular nucleic acid structures form in the specific DNA and RNA G-rich sequences with biological significance such as human telomeres, oncogene-promoter regions, replication initiation sites, and 5' and 3'-untranslated (UTR) regions. The non-canonical G-quadruplex secondary structures can readily form under physiologically relevant ionic conditions and are considered to be new molecular target for cancer therapeutics. This review discusses the essential progress in our lab related to the structures and functions of biologically relevant DNA G-quadruplexes in human gene promoters and telomeres, and the opportunities presented for the development of G-quadruplex-targeted small-molecule drugs.

2014 Vol. 57 (12): 1605-1614 [Abstract] ( 302 ) [ PDF (4128 KB)   ] ( 143 )  [Supporting InformationDOI: 10.1007/s11426-014-5235-3
Received: 2014-07-07; Accepted: 2014-07-28; Published Online: 2014-11-13
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Tightening up the structure, lighting up the pathway: application of molecular constraints and light to manipulate protein folding, self-assembly and function Hot!
MARKIEWICZ Beatrice N., CULIK Robert M., GAI Feng

Chemical cross-linking provides an effective avenue to reduce the conformational entropy of polypeptide chains and hence has become a popular method to induce or force structural formation in peptides and proteins. Recently, other types of molecular constraints, especially photoresponsive linkers and functional groups, have also found increased use in a wide variety of applications. Herein, we provide a concise review of using various forms of molecular strategies to constrain proteins, thereby stabilizing their native states, gaining insight into their folding mechanisms, and/or providing a handle to trigger a conformational process of interest with light. The applications discussed here cover a wide range of topics, ranging from delineating the details of the protein folding energy landscape to controlling protein assembly and function.

2014 Vol. 57 (12): 1615-1624 [Abstract] ( 302 ) [ PDF (2172 KB)   ] ( 104 )  [Supporting InformationDOI: 10.1007/s11426-014-5225-5
Received: 2014-07-07; Accepted: 2014-08-18; Published Online: 2014-10-28
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Bacterial persistence Hot!
LIU YunXiao, YANG Jin, ZHAO ZhiLun, PU YingYing, BAI Fan

Although bacterial persistence was first observed in 1944, its underlying mechanism is just beginning to be understood and many fundamental questions remain. In this review, we summarize studies in order to chart the full map of bacterial persistence. Because persistence significantly contributes to disease recalcitrance, we also elucidate the probable relationships between bacterial persistence and prolonged chronic infections, with some comments on future research directions and therapeutic strategies.

2014 Vol. 57 (12): 1625-1633 [Abstract] ( 231 ) [ PDF (1894 KB)   ] ( 126 )  [Supporting InformationDOI: 10.1007/s11426-014-5245-1
Received: 2014-07-07; Accepted: 2014-07-28; Published Online: 2014-11-03
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Self-assembly of surfactant-like peptides and their applications
ZHANG JingHui, ZHAO YuRong, HAN ShuYi, CHEN CuiXia, XU Hai

Numerous peptides derived from naturally occurring proteins or de novo designed have been found to self-assemble into various nanostructures. These well-defined nanostructures have shown great potential for a variety of biomedical and biotechnological applications. In particular, surfactant-like peptides (SLPs) have distinctive advantages in their length, aggregating ability, and water solubility. In this article, we report recent advances in the mechanistic understanding of the self-assembly principles of SLPs and in their applications, most of which have been made in our laboratory. Hydrogen bonding between peptide backbones, hydrophobic interaction between hydrophobic side chains, and electrostatic repulsion between charged head groups all have roles in mediating the self-assembly of SLPs; the final self-assembled nanostructures are therefore dependent on their interplay. SLPs have shown diverse applications ranging from membrane protein stabilization and antimicrobial/anticancer agents to nanofabrication and biomineralization. Future advances in the self-assembly of SLPs will hinge on their large-scale production, the design of new functional SLPs with targeted properties, and the exploitation of new or improved applications.

2014 Vol. 57 (12): 1634-1645 [Abstract] ( 334 ) [ PDF (4152 KB)   ] ( 77 )  [Supporting InformationDOI: 10.1007/s11426-014-5234-4
Received: 2014-07-09; Accepted: 2014-08-25; Published Online: 2014-11-05
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Advanced experimental methods toward understanding biophysicochemical interactions of interfacial biomolecules by using sum frequency generation vibrational spectroscopy
YE ShuJi, LUO Yi

Sum frequency generation vibrational spectroscopy (SFG-VS) has been demonstrated to be a powerful technique to study the interfacial structures and interactions of biomolecules at the molecular level. Yet most previous studies mainly collected the SFG spectra in the frequency range of 1500-4000 cm-1, which is not always sufficient to describe the detailed interactions at surface and interface. Thorough knowledge of the complex biophysicochemical interactions between biomolecules and surface requires new ideas and advanced experimental methods for collecting SFG vibrational spectra. We introduced some advanced methods recently exploited by our group and others, including (1) detection of vibration modes in the fingerprint region; (2) combination of chiral and achiral polarization measurements; (3) SFG coupled with surface plasmon polaritons (SPPs); (4) imaging and microscopy approaches; and (5) ultrafast time-resolved SFG measurements. The technique that we integrated with these advanced methods may help to give a detailed and high-spatial-resolution 3D picture of interfacial biomolecules.

2014 Vol. 57 (12): 1646-1661 [Abstract] ( 357 ) [ PDF (3873 KB)   ] ( 126 )  [Supporting InformationDOI: 10.1007/s11426-014-5233-5
Received: 2014-07-09; Accepted: 2014-08-06; Published Online: 2014-11-03
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Computer simulation studies on the interactions betweennanoparticles and cell membrane
TIAN FaLin, YUE TongTao, LI Ye, ZHANG XianRen

In recent times, nanoparticles (NPs) have received intense attention not only due to their potential applications as a candidate for drug delivery, but also because of their undesirable effects on human health. Although extensive experimental studies have been carried out in literature in order to understand the interaction between NPs and a plasma membrane, much less is known about the molecular details of the interaction mechanisms and pathways. As complimentary tools, coarse grained molecular dynamics (CGMD) and dissipative particle dynamics (DPD) simulations have been extensively used on the interaction mechanism and evolution pathway. In the present review we summarize computer simulation studies on the NP-membrane interaction, which developed over the last few years, and particularly evaluate the results from the DPD technique. Those studies undoubtedly deepen our understanding of the NP-membrane interaction mechanisms and provide a design guideline for new NPs.

2014 Vol. 57 (12): 1662-1671 [Abstract] ( 313 ) [ PDF (2588 KB)   ] ( 81 )  [Supporting InformationDOI: 10.1007/s11426-014-5231-7
Received: 2014-07-09; Accepted: 2014-07-21; Published Online: 2014-11-04
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Surface modification of natural cellulose substances: toward functional materials and applications Hot!
LUO Yan, HUANG JianGuo

Combining various synthetic chemical processes and biological assemblies provides a promising strategy for the design and fabrication of functional materials with tailored structures and properties. The unique multilevel structures and morphologies of natural cellulose substances such as ordinary commercial laboratory filter paper make them ideal platforms for the self-assemblies of various functional guest molecules that are to be deposited on the surfaces of their fine structures, and the resulting composite matters show significant potentials for various applications. The surface sol-gel process was employed to deposit ultrathin metal-oxide (e.g., titania and zirconia) gel films to coat the cellulose nanofibers in bulk filter papers; thereafter, monolayers of specific guest substrates were immobilized onto the surfaces of the metal-oxide gel films. Highly selective, sensitive, and reversible chemosensors based on the surface modification of filter paper were obtained toward the fluorescence and colorimetric detection of various analytes such as heavy-metal ions, inorganic anions, amino acids, and gases. Cellulose-based composite materials with superhydrophobic, antibacterial, or luminescent properties were fabricated by self-assembly approaches toward practical applications.

2014 Vol. 57 (12): 1672-1682 [Abstract] ( 261 ) [ PDF (4504 KB)   ] ( 152 )  [Supporting InformationDOI: 10.1007/s11426-014-5226-4
Received: 2014-07-08; Accepted: 2014-07-28;
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Selective aggregation of membrane proteinsby membrane-mediated interactions
LI ShuangYang, ZHANG XianRen, WANG WenChuan

There are different types of membrane proteins in a cellular membrane, and most of them must correctly assemble into appropriate clusters for their cellular functions. In this work, we suggest a physical mechanism for selective aggregation of different membrane proteins without specific protein-protein attraction by dissipative particle dynamics method. A membrane-mediated interaction may result in different protein clusters with ideal mixing, nonideal mixing and demixing of different types of membrane proteins, depending on the extent of the similarity of membrane deformations by those proteins.

2014 Vol. 57 (12): 1683-1689 [Abstract] ( 184 ) [ PDF (3106 KB)   ] ( 51 )  [Supporting InformationDOI: 10.1007/s11426-014-5227-3
Received: 2014-07-08; Accepted: 2014-08-12; Published Online: 2014-10-31
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Investigation of nitroxoline-human serum albumin interactions by spectroscopic methods

Nitroxoline is a wide spectrum antibacterial and is one of the most important urinary antiseptics. The interaction between nitroxoline and human serum albumin (HSA) has been investigated systematically by fluorescence spectroscopy, synchronous fluorescence, three-dimensional fluorescence, CD spectroscopy and UV-Vis absorption spectroscopy. The results indicated that the quenching of HSA by nitroxoline was static. The corresponding thermodynamic parameters ΔH, ΔS and ΔG calculated according to van't Hoff equation revealed that the intermolecular forces acting between nitroxoline and HSA were mainly hydrogen bonding and van der Waals forces. The conformational changes in the interaction were studied by synchronous fluorescence, CD spectroscopy and three-dimensional fluorescence spectra which showed changes in the microenvironment and conformation of HSA.

2014 Vol. 57 (12): 1690-1695 [Abstract] ( 214 ) [ PDF (1722 KB)   ] ( 75 )  [Supporting InformationDOI: 10.1007/s11426-014-5230-8
Received: 2014-07-08; Accepted: 2014-07-29; Published Online: 2014-10-30
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Logic-signal output of fluorescent proteins for screening antibiotic combinations Hot!
LV FengTing, LIU LiBing, WANG Shu

A new method to screen antibiotic combinations is demonstrated, which takes advantage of the logic-signal output of genetically engineered drug-resistant E. coli strains expressing different fluorescent proteins. Thirty-six antibiotic combinations for nine antibiotics were investigated. The operation of different logic gates can reveal the susceptibility, resistance, or synergistic effect of the antibiotic combinations in a rapid (7-8 h versus 24-28 h for typical growth-based assays), simple, quantitative and high-throughput manner. This logic-signal-based output patterns provide the basis for novel and reliable screening of antibiotic combinations and help us to both gain insight into the mechanisms of multi-drug action.

2014 Vol. 57 (12): 1696-1702 [Abstract] ( 178 ) [ PDF (1960 KB)   ] ( 101 )  [Supporting InformationDOI: 10.1007/s11426-014-5224-6
Received: 2014-07-08; Accepted: 2014-08-01; Published Online: 2014-11-03
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Subsolidus binary phase diagram of the bilayer compounds [n-CnH2n+1N(CH3)3]2ZnCl4 (n = 16, 18)
RUAN Bei, WU KeZhong, CHEN Jing, XIONG YuanYuan, REN BiYan

The bilayer compounds [n-CnH2n+1N(CH3)3]2ZnCl4 (n = 16, 18) experience solid-solid phase transition within the temperature range of 310 to 340 K. The low-temperature crystal structures of the pure compounds are characteristic of the piling effect in which a 2D macro-anion ZnCl42- is sandwiched between two alkylammonium layers. These layers become conformationally disordered in the high-temperature phases. The structures can alternatively be viewed as a double layer of alkylammonium ions between ZnCl42- sheets and can be considered as crystalline models of lipid bilayers. The experimental subsolidus binary phase diagram of [n-C16H33N(CH3)3]2ZnCl4-[n-C18H37N(CH3)3]2ZnCl4 has also been established over the whole composition range by differential scanning calorimetry (DSC) and X-ray diffraction. In the phase diagram, one intermediate compound [n-C16H33N(CH3)3][n-C18H37N(CH3)3]ZnCl4 at WC16C3Zn% 47.50 and two eutectoid invariants points at WC16C3Zn% 35.10 and 75.70 were observed; the respective temperatures of the two eutectoids are 320 ± 1 and 315 ± 1 K. In addition, there are three noticeable solid solution ranges in the phase diagram: α-phase at the left, β-phase at the right, and γ-phase in the middle.

2014 Vol. 57 (12): 1703-1707 [Abstract] ( 190 ) [ PDF (5006 KB)   ] ( 60 )  [Supporting InformationDOI: 10.1007/s11426-014-5236-2
Received: 2014-07-09; Accepted: 2014-08-21; Published Online: 2014-10-30
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Energetics of protein backbone hydrogen bonds and their local electrostatic environment
DUAN Li L., GAO Ya, JI Chang G., MEI Ye, ZHANG Qing G., TANG Bo, ZHANG John Z. H.

MD simulation study of several peptides including a polyalanine, a helix (pdb:2I9M), and a leucine zipper were carried out to investigate hydrogen bond energetics using dynamic polarized protein-specific charge (DPPC) to account for the polarization effect in protein dynamics. Results show that the backbone hydrogen-bond strength is generally correlated with its specific local electrostatic environment, measured by the number of water molecules near the hydrogen bond in the first solvation shell. The correlation coefficient is found to be 0.89, 0.78, and 0.80, respectively, for polyalanine, 2I9M protein, and leucine zipper. In the polyalanine, the energies of the backbone hydrogen bonds are very similar to each other due to their similar local electrostatic environment. The current study helps demonstrate and support the understanding that hydrogen bonds are stronger in a hydrophobic surrounding than in a hydrophilic one. For comparison, the result from simulation using standard force field shows a much weaker correlation between hydrogen bond energy and local electrostatic environment due to the lack of polarization effect in the force field.

2014 Vol. 57 (12): 1708-1715 [Abstract] ( 231 ) [ PDF (1111 KB)   ] ( 47 )  [Supporting InformationDOI: 10.1007/s11426-014-5246-0
Received: 2014-07-09; Accepted: 2014-09-09;
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Single-molecule-force spectroscopy study of the mechanism of interactions between TSP-1 and CD47
PAN YanGang, WANG Feng, LIU YanHou, YANG Yong-Guang, WANG HongDa

The 4N1K peptide, which is derived from the C-terminal domain of thrombospondin-1 (TSP-1), is usually used as a functional mimic peptide for TSP-1. Knowledge about the interaction force of 4N1K/CD47 is important in explaining how TSP-1 affects the biological effect of CD47. Here we used a single-molecule force spectroscopy (SMFS) technique to explore the interaction of 4N1K/CD47 on both normal and oxidative human red blood cells (hRBCs) at single-molecule level. There was no interaction force between 4N1K and CD47 on normal hRBCs; however, we did find 4N1K-bound CD47 on oxidative hRBCs. We also detected interaction forces for 4N1K/CD47ex (extracellular domain of human CD47), and 4N1K/oxidative CD47ex. The interaction forces of 4N1K/CD47ex were almost consistent with those of 4N1K/oxidative CD47ex at the same loading rate. These results suggest that the conformational change of CD47 is critical for 4N1K-CD47 interaction on oxidative hRBCs.

2014 Vol. 57 (12): 1716-1722 [Abstract] ( 165 ) [ PDF (1775 KB)   ] ( 52 )  [Supporting InformationDOI: 10.1007/s11426-014-5232-6
Received: 2014-07-08; Accepted: 2014-07-30; Published Online: 2014-11-10
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Simulating ion clustering in potassium thiocyanate aqueous solutions with various ion-water models
WANG TianJun, ZHANG RuiTing, WU TianMin, LI HuanHuan, ZHUANG Wei

Using a molecular dynamics simulation technique, we compared several commonly used ion-water models to describe the microscopic structures and dynamics in KSCN aqueous solutions. Results are compared with observations of femtosecond infrared vibrational-energy transfer and anisotropy measurements. The Jorgensen/TIP4P model is found to provide the best reproduction of clustering properties such as percentage of clustered ions, cluster-size distribution, concentration dependence of the water, and ion-rotation time constants.

2014 Vol. 57 (12): 1723-1730 [Abstract] ( 284 ) [ PDF (834 KB)   ] ( 48 )  [Supporting InformationDOI: 10.1007/s11426-014-5244-2
Received: 2014-07-09; Accepted: 2014-09-11; Published Online: 2014-11-10
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Trimer formation of 6-methyl-1,3,5-triazine-2,4-diamine in salt with organic and inorganic acids: analysis of supramolecular architecture
XIAO ZhenYu, WANG WenQiang, XUE RuiYu, ZHAO Lei, WANG Lei, ZHANG YiHeng

Although the numbers of co-crystals, salts, polymorphs, hydrates, and solvates are growing steadily, trimers that contain both inorganic and organic acids are still very rare in the Cambridge Structural Database (CSD). When 3,5-dihydroxybenzoic acid was crystallized readily with 6-methyl-1,3,5-triazine-2,4-diamine in a 4:3 ratio of ethanol and water by adding a few drops of nitric acid upon slow evaporation in ambient conditions, 6-methyl-1,3,5-triazine-2,4-diamine and 3,5-dihydroxybenzoic acid with the nitric acid form of 1:1:1 an inorganic-organic salt formulated as [(C4H8N5+)·(NO3-)·(C7H6O4)]. The supramolecular architecture, which is quite elegant and simple, appeared as stacking of a 3D network in adduct. Proton transfer from the HNO3 to 6-methyl-1,3,5-triazine-2,4-diamine N acceptor (triazine N) occurred in the organic salt and led to the ionic heterosynthon in the structure. Cooperation among the -COOH, -OH, NO3-, and -NH-functional groups for the observed hydrogen bond synthon was examined in the structure. In adduct, recognition among the constituents is established through N-H…O, O-H…N, and O-H…O hydrogen bonds. The agomelatine molecules are linked through the intermolecular hydrogen bonding interactions (O-H…O) to form a 1D chain. In addition, the nitric acid anions and base cations act as donors and acceptors of hydrogen bonds and interlink, almost to co-planarity, the hydrogen-bonded chains through interchain N-H…O, O-H…N, as well as O-H…O interactions into a 2D sheet structure. Persistent N-H…O interactions were found to play an important role in the formation of the final 3D array. The salt was characterized by elemental analysis, IR, thermogravimetric analysis, and single-crystal X-ray diffraction, to better understand how intermolecular interactions influence its supramolecular assembly.

2014 Vol. 57 (12): 1731-1737 [Abstract] ( 262 ) [ PDF (1568 KB)   ] ( 178 )  [Supporting InformationDOI: 10.1007/s11426-014-5101-3
Received: 2014-01-02; Accepted: 2014-01-27; Published Online: 2014-06-10
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Complexation of DNA with cationic surfactants as studied by small-angle X-ray scattering
NIU Lin, YAN JingJing, YANG XuYan, BURGER Christian, RONG LiXia, HSIAO Benjamin, LIANG DeHai

The phase behaviors of the complex formed by didodecyldimethylammonium bromide (DDAB) and cetyltrimethylammonium bromide (CTAB) interacting with three different types of DNAs, salmon testes DNA (~2000 bp), 21-bp double-stranded oligonucleotides (oligo-dsDNA), and 21-nt single-stranded oligonucleotides (oligo-ssDNA) were studied by synchrotron small-angle X-ray scattering. It was found that the DNA length and flexibility, together with the positive/negative charge ratio, determined the final structure. At higher charge ratios, the DNA length exhibited negligible effect. Both oligo-dsDNA and salmon DNA formed inverted hexagonal packing of cylinders with CTAB, as well as bilayered lamella with DDAB. However, at lower charge ratios, oligo-dsDNA formed a distorted hexagonal phase with CTAB and a new structure with DDAB, which was different from the behaviors of salmon DNA. The flexible oligo-ssDNA formed rich structures that were subject to environmental disturbance. Kinetic study also indicated that the structures of the complex formed by oligo-ssDNA took much longer to mature than the structures formed by oligo-dsDNA. We attributed this result to the conformational adjustment of oligo-ssDNA in the complex.

2014 Vol. 57 (12): 1738-1745 [Abstract] ( 135 ) [ PDF (1075 KB)   ] ( 36 )  [Supporting InformationDOI: 10.1007/s11426-014-5159-y
Received: 2014-03-03; Accepted: 2014-03-21;
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Outgassing analysis of molecular glass photoresists under EUV irradiation
CHEN Li, XU Jian, YUAN Hua, YANG ShuMin, WANG LianSheng, WU YanQing, ZHAO Jun, CHEN Ming, LIU HaiGang, LI ShaYu, TAI RenZhong, WANG ShuangQing, YANG GuoQiang

A device was designed and assembled to analyze the outgassing of molecular glass (MG) photoresists under extreme ultraviolet (EUV) exposure. The outgassing of the photoresists with different components and different concentrations of tert-butoxycarbonyl (t-Boc), photo-generated acid (PAG), and acid quencher was systematically investigated. Based on experiments, some solutions for reducing the outgassing of MG photoresists were proposed.

2014 Vol. 57 (12): 1746-1750 [Abstract] ( 167 ) [ PDF (2116 KB)   ] ( 93 )  [Supporting InformationDOI: 10.1007/s11426-014-5122-y
Received: 2014-01-22; Accepted: 2014-02-19; Published Online: 2014-06-10
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Molecularly imprinted polymer for pre-concentration of esculetin from tobacco followed by the UPLC analysis
RAZWAN SARDAR M., JIN Yan, KONG GuangHui, LI HaiFang, LIN Jin-Ming

Molecularly imprinted polymers (MIPs) for solid-phase extraction and pre-concentration of esculetin have been successfully prepared by the bulk polymerization method using esculetin as a template molecule. Polymers of varying composition were prepared using different monomers (4-vinylpyridine, methacrylic acid, and acrylamide), ethylene glycol dimethacrylate as the cross-linker, 2,2-azobis(2-methylpropinitrile) as the initiator, and different porogen solvents (ethanol, acetone/methanol, and acetonitrile). The best polymer was obtained when 4-vinylpyridine was used as the monomer and acetone/methanol (3:2) as the porogen solvent, whereas the template:-monomer:-cross-linker ratio was 1:4:20. The imprinting factor of the selected MIPs for esculetin was 3.77. The polymers were evaluated according to their selective recognition properties for esculetin and structurally-related compounds (esculin, scopoletin, coumarin, and 7-methoxycoumarin). Chemical and morphological characterizations of the polymers were investigated by FTIR and scanning electron microscope, which confirmed a high degree of polymerization. Surface area, pore volume, and pore size of the polymer were investigated by Brunauer-Emmett-Teller analysis. MIPs were also successfully used as solid-phase adsorbent materials for the extraction of esculetin from tobacco leaves. Esculetin contents in dried tobacco leaves were found to be (9.27±0.17) μg g-1.

2014 Vol. 57 (12): 1751-1759 [Abstract] ( 179 ) [ PDF (4229 KB)   ] ( 110 )  [Supporting InformationDOI: 10.1007/s11426-014-5180-1
Received: 2014-01-07; Accepted: 2014-03-23; Published Online: 2014-11-06
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Extraction of coal-tar pitch using NMP/ILs mixed solvents
HUANG JinCheng, LI ChunShan, BAI Lu, NIE Yi, WANG ErQiang, HE YuJian, ZHANG SuoJiang

Coal-tar pitch (CP) is a promising carbon raw material for producing needle coke, carbon fiber etc. During processing, the H/C ratio, ash content, and quinoline insoluble (QI) in the CP are the key factors that influence the material preparation. In this study, NMP was selected to extract CP first; then [BMIM]Cl/NMP mixed solvent was used; and finally a series of ionic liquids (ILs) mixtures with NMP were developed for the extraction of CP to obtain the refined pitch. The extracts were analyzed via elemental analysis, TGA, FT-IR, and 13C-NMR. Results indicate that different NMP/IL mass ratios or different kinds of ILs have impact on the extraction yield. The relationship of the hydrogen to carbon (H/C) ratio changed with different solvents and QI extracts were obtained. Results showed that the H/C ratios changed little between NMP extracts and could be adjusted by changing the NMP/ILs mass ratio or using different ILs. The extracts are suitable for preparation mesophase pitch because of no ash content, low QI, and appropriate H/C ratios. As a result, NMP can be used to refine pitch. In addition, [BMIM]Cl is good mixed with NMP for CP extraction, because it can obtain a relatively high yield under the same extraction conditions.

2014 Vol. 57 (12): 1760-1765 [Abstract] ( 268 ) [ PDF (548 KB)   ] ( 86 )  [Supporting InformationDOI: 10.1007/s11426-014-5189-5
Received: 2014-04-03; Accepted: 2014-04-25; Published Online: 2014-08-25
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Simultaneous desulfurization and denitrogen of liquid fuels using two functionalized group ionic liquids
NIE Yi, GONG Xue, GAO HongShuai, ZHANG XiangPing, ZHANG SuoJiang

Deep desulfurization of liquid fuels is an important and challenging issue in worldwide petroleum refining industry. Extraction and catalytic oxidative desulfurization (ECODS) of liquid fuels using a series of ionic liquids (ILs) with two functionalized groups, such as [(CH2)2COOHmim]Cl/nFeCl3, [(CH2)2COOHmim]Cl/nZnCl2, and [Amim]Cl/nFeCl3, was studied. In the ECODS, the ILs were used as both extractant and catalyst and 30 wt% hydrogen peroxide (H2O2) solution as oxidant. The effects of molar ratios of [(CH2)2COOHmim]Cl (or [Amim]Cl) to FeCl3 (or ZnCl2) in ILs, H2O2/sulfur (O/S) molar ratio, reaction temperature, and the nature of sulfur compounds on sulfur removal were investigated. The natures of the functional groups (-COOH, -CH2-CH=CH2) in cations and the acid strength of anions play important roles in the ECODS and affect the reaction time, temperature, and desulfurization efficiency of different substrates. Also, nitrogen-containing compounds (pyridine, pyrrole, and quinoline) could be removed simultaneously in the ECODS and had different effects on dibenzothiophene removal.

2014 Vol. 57 (12): 1766-1773 [Abstract] ( 295 ) [ PDF (379 KB)   ] ( 95 )  [Supporting InformationDOI: 10.1007/s11426-014-5164-1
Received: 2014-03-06; Accepted: 2014-04-09; Published Online: 2014-11-05
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Asphaltene precipitation modeling through ACE reaping of scaling equations

Precipitation and deposition of asphaltene have undesirable effects on the petroleum industry by increasing operational costs due to reduction of well productivity as well as catalyst poisoning. Herein we propose a reliable model for quantitative estimation of asphaltene precipitation. Scaling equation is the most powerful and popular model for accurate prediction of asphaltene precipitated out of solution in crudes without regard to complex nature of asphaltene. We employed a new mathematical-based approach known as alternating conditional expectation (ACE) technique for combining results of different scaling models in order to increase the accuracy of final estimation. Outputs of three well-known scaling equations, including Rassamdana (RE), Hu (HU), and Ashoori (AS), are input to ACE and the final output is produced through a nonlinear combination of scaling equations. The proposed methodology is capable of significantly increasing the precision of final estimation via a divide-and-conquer principle in which ACE functions as the combiner. Results indicate the superiority of the proposed method compared with other individual scaling equation models.

2014 Vol. 57 (12): 1774-1780 [Abstract] ( 209 ) [ PDF (1370 KB)   ] ( 84 )  [Supporting InformationDOI: 10.1007/s11426-014-5253-1
Received: 2014-05-21; Accepted: 2014-07-14; Published Online: 2014-11-18
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