Coating metal-organic frameworks on plasmonic Ag/AgCl nanowire for boosting visible light photodegradation of organic pollutants.

Photoactive metal-organic frameworks, MIL-100(Fe), with controllable thickness are coated on plasmonic Ag/AgCl nanowire, for boosting visible light photodegradation of rhodamine B and tetracycline hydrochloride. The morphology and composition of the obtained nano-heterostructure were investigated in detail by SEM imaging, TEM imaging, XRD patterns, FT-IR spectra, N2 adsorption-desorption curves and TGA patterns. Photoelectric performance test suggested that a Z-scheme photocatalysis system for efficient transfer of photogenerated charge carriers was established between MIL-100(Fe) and plasmonic Ag/AgCl nanowire.

Photocatalytic Performance of the MOF-Coating Layer on SPR-Excited Ag Nanowires.

The photoactive metal-organic frameworks (MOFs) were controllably coated on the surface plasmon resonance-excited Ag nanowires in a layer manner to adjust the photocatalytic activity. The influence of the thickness of the MOF coating layer on the photocatalytic activity was investigated. A thicker MOF coating layer not only facilitated the photogenerated electron-hole separation efficiency but also provided a larger Brunauer-Emmett-Teller surface area, thus enhancing the photocatalytic activity. This work provided a new way to adjust the photocatalytic activity of the photoactive MOF.

Peroral traction-assisted natural orifice trans-anal flexible endoscopic rectosigmoidectomy followed by intracorporeal colorectal anastomosis in a live porcine model.

BACKGROUND: Compared to traditional open surgery, laparoscopic surgery has become a standard approach for colorectal cancer due to its great superiorities including less postoperative pain, a shorter hospital stay, and better quality of life. In 2007, Whiteford et al reported the first natural orifice trans-anal endoscopic surgery (NOTES) sigmoidectomy using transanal endoscopic microsurgery. To date, all cases of NOTES colorectal resection have included a hybrid laparoscopic approach with the use of established rigid platforms. AIM: To introduce a novel technique of peroral external traction-assisted transanal NOTES rectosigmoidectomy followed by intracorporeal colorectal end-to-end anastomosis by using only currently available and flexible endoscopic instrumentation in a live porcine model. METHODS: Three female pigs weighing 25-30 kg underwent NOTES rectosigmoid resection. After preoperative work-up and bowel preparation, general anesthesia combined with endotracheal intubation was achieved. One dual-channel therapeutic endoscope was used. Carbon dioxide insufflation was performed during the operation. The procedure of trans-anal NOTES rectosigmoidectomy included the following eight steps: (1) The rectosigmoid colon was tattooed with India ink by submucosal injection; (2) Creation of gastrostomy by directed submucosal tunneling; (3) Peroral external traction using endoloop ligation; (4) Creation of rectostomy on the anterior rectal wall by directed 3 cm submucosal tunneling; (5) Peroral external traction-assisted dissection of the left side of the colon; (6) Trans-anal rectosigmoid specimen transection, where an anvil was inserted into the proximal segment after purse-string suturing; (7) Intracorporeal colorectal end-to-end anastomosis using a circular stapler by a single stapling technique; and (8) Closure of gastrostomy using endoscopic clips. All animals were euthanized immediately after the procedure, abdominal exploration was performed, and the air-under-water leak test was carried out. RESULTS: The procedure was completed in all three animals, with the operation time ranging from 193 min to 259 min. Neither major intraoperative complications nor hemodynamic instability occurred during the operation. The length of the resected specimen ranged from 7 cm to 13 cm. With the assistance of a trans-umbilical rigid grasper, intracorporeal colorectal, tension-free, end-to-end anastomosis was achieved in the three animals. CONCLUSION: Peroral traction-assisted transanal NOTES rectosigmoidectomy followed by intracorporeal colorectal end-to-end anastomosis is technically feasible and reproducible in an animal model and is worthy of further improvements.

Controlling crystal growth of MIL-100(Fe) on Ag nanowire surface for optimizing catalytic performance.

Ag/MIL-100(Fe) core/sheath nanowire with controllable thickness of the MIL-100(Fe) sheath was prepared by controlling the crystal growth of MIL-100(Fe) on the Ag nanowire surface. The evolution of the MIL-100(Fe) sheath monitored by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), thermogravimetric analyses (TGA), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FT-IR), and N2 adsorption-desorption analysis indicates that the thickness of the MIL-100(Fe) sheath increases with the increasing number of crystal growth cycles of MIL-100(Fe) on the Ag nanowire surface. Catalytic reaction over Ag/MIL-100(Fe) core/sheath nanowire suggests that the thickness of the MIL-100(Fe) sheath largely influences the catalytic performance and it is quite important to control the crystal growth of MIL-100(Fe) on the Ag nanowire surface for optimizing catalytic performance.

CTX-M-137, a hybrid of CTX-M-14-like and CTX-M-15-like ß-lactamases identified in an Escherichia coli clinical isolate.

OBJECTIVES: To characterize a novel CTX-M chimera, CTX-M-137, from Escherichia coli clinical isolates in China. METHODS: Isolates were collected from five hospitals between 22 February 2009 and 20 December 2011. Resistance genes were investigated by PCR. blaCTX-M-137 was cloned and purified for kinetic measurements. Conjugation experiments, S1-PFGE and Southern blotting were performed to study the plasmid harbouring blaCTX-M-137. The genetic environment of blaCTX-M-137 was determined by genomic cloning and sequencing. RESULTS: A total of 247 cephalosporin-resistant E. coli were identified. blaCTX-M group genes were the most prevalent extended-spectrum ß-lactamase (ESBL) genes, with 71 isolates harbouring blaCTX-M-1 group genes and 137 isolates harbouring blaCTX-M-9 group genes. A novel chimera of CTX-M-14-like and CTX-M-15-like ESBLs, designated CTX-M-137, was identified from a 60-year-old man with a urinary tract infection. The N-terminus of CTX-M-137 matched CTX-M-14 and the C-terminus matched CTX-M-15. CTX-M-137 conferred resistance to ceftazidime, cefotaxime and aztreonam. Purified CTX-M-137 showed good hydrolytic activity against ceftazidime and cefotaxime, and was inhibited by clavulanic acid. The blaCTX-M-137 was carried on an ∼83 kb IncI1 plasmid. blaCTX-M-137 was carried on a complete transposition unit ISEcp1-blaCTX-M-137-Δorf477 inserted into yagA, which is part of the IncI1 plasmid backbone. CONCLUSIONS: We identified a novel CTX-M chimera, CTX-M-137, with a CTX-M-14-like N-terminus and a CTX-M-15-like C-terminus. Our findings suggest an ongoing diversification of CTX-M-type ESBLs through recombination events.

Outbreak of PER-1 and diversity of ß-lactamases among ceftazidime-resistant Pseudomonas aeruginosa clinical isolates.

A growing number of ß-lactamases have been reported in Pseudomonas aeruginosa clinical isolates. The aim of this study was to investigate the diversity of ß-lactamases in the collection of 51 ceftazidime-resistant P. aeruginosa clinical isolates in four hospitals of southern China. Among these isolates, variable degrees of resistance to other ß-lactam and non-ß-lactam agents were observed. Pulsed-field gel electrophoresis (PFGE) revealed a high degree of clonality with five main genotypes. Of the 51 isolates tested, 35 (68.6%) were identified as extended-spectrum ß-lactamase (ESBL) producers, with 35 producing PER-1, 1 CTX-M-3, 7 CTX-M-15 and 1 CTX-M-14. Most (82.9%, 29/35) PER-1-producing isolates were collected from two hospitals between January and April in 2008 and belonged to the same PFGE pattern (pattern B) with similar antibiogram and ß-lactamase profiles, which suggested an outbreak of this clone at the time. The prevalence of CTX-M-type ESBL (17.6%, 9/51) was unexpectedly high. One isolate was identified as producing VIM-2. Furthermore, we also reported an occurrence of a novel OXA-10 variant, OXA-246, in 14 P. aeruginosa isolates. In addition, AmpC overproduction was found to be the ß-lactamase-mediated mechanism responsible for ceftazidime resistance in 6 isolates (11.8%). Our results revealed an overall diversity of ß-lactamases and outbreak of a PER-1-producing clone among ceftazidime-resistant P. aeruginosa in southern China.

OprD mutations and inactivation in imipenem-resistant Pseudomonas aeruginosa isolates from China.

To investigate the mechanisms involved in imipenem resistance of Pseudomonas aeruginosa in southern China, 61 imipenem-resistant P. aeruginosa clinical isolates were collected from 4 hospitals between October 2011 and June 2012. All isolates were resistant to imipenem, whereas 21.3% were susceptible or intermediate to meropenem. Variable degrees of resistance to other ß-lactam and non-ß-lactam antimicrobials were observed. PFGE revealed high-level of clonal diversity. Among the 61 isolates, 50 isolates had OprD loss by disrupted oprD mutations, including 43 with frameshift mutations of oprD and 7 with a premature stop codon by single point mutation. Six isolates were oprD-negative by PCR, suggestive of a major disruption of oprD genes. Five isolates had intact oprD but had reduced expression of oprD genes. In addition, only one isolate with disrupted oprD mutation by a premature stop codon was confirmed to be a metallo-ß-lactamase producer (IMP-9). Our results show that the loss of OprD, as well as reduced expression of oprD and MBL production, were the predominant mechanisms of imipenem resistance in P. aeruginosa in southern China.

Tubular metal-organic framework-based capillary gas chromatography column for separation of alkanes and aromatic positional isomers.

In this work, a tubular metal-organic framework, MOF-CJ3, with a large one-dimensional channel was chosen as stationary phase to prepare a capillary gas chromatographic column via a verified dynamic coating procedure. The column offered good separations of linear and branched alkanes, as well as aromatic positional isomers (ethylbenzene, xylene, cresol, hydroquinone, dichlorobenzene, bromobenzonitrile, chloronitrobenzene, and nitrotoluene) based on a combination of host-guest interactions and adsorption effects. Elution sequence of most of the analytes followed an increasing order of their boiling points, except for the separation of n-heptanes/isooctane, cresol, and hydroquinone isomers. Separation behavior of the column upon different organic substances may be related to the tubular pore structure of MOF-CJ3, in which the van der Waals forces between the alkanes and the hydrophobic inner surfaces might have great effect on separation of n-heptanes and isooctane, whereas the separation of cresol and hydroquinone isomers were affected by (OH⋯O) hydrogen bonds formed between the analytes and the 1,3,5-benzenetricarboxylate ligands on the pore wall. The effects of temperature on separation of aromatic positional isomers were investigated to elucidate entropy and enthalpy controlling of the separation process.

Chiral discrimination and interaction mechanism between enantiomers and serum albumins.

The chiral discrimination studies of biological system are theoretically and practically significant for the development of chiral drugs and life science. Our work has embarked upon the interaction between serum albumin (SA) (including human SA and bovine SA), R,S-1-(4-methoxyphenyl)ethylamine, and R,S-1-(3-methoxyphenyl)ethylamine. The formation of intermediate transition state, binding sites, and chiral discrimination ability can be investigated by ultraviolet-visible spectra and fluorescence spectra. Moreover, both the changes of hydrophobic microenvironment and energy transfer can be detected by synchronous fluorescence spectra and fluorescence lifetime.

Semi-preparative enantiomeric separation of ofloxacin by HPLC.

A direct semi-preparative high performance liquid chromatography (HPLC) enantioseparation of ofloxacin was performed on chemically immobilized cyclodextrin derivative-mono (6A-azido-6A-deoxy)-per(p-chlorophenyl carbamoylated) ß-CD chiral stationary phase. Conditions for semi-preparative separations were established using a 250 × 4.6 mm i.d. column and subsequently extended to a 250 × 10.0 mm i.d. column that enabled separations on a milligram scale. Optimization of the chromatographic conditions (mobile phase and column load) with respect to better efficiency, resolution and peak retention resulted in a system capable of separating up to 304 mg of (-)-(S)-ofloxacin and 56 mg of (+)-(R)-ofloxacin of the racemate over 6 h. The purities of the separated enantiomers were determined by HPLC. Moreover, both separated enantiomers were characterized by mass spectrometry; then, the absolute configuration of the products was clearly confirmed by polarimetry.

2-(Benzothia-zol-2-yl-sulfanyl)-acetic acid.

In the title compound, C(9)H(7)NO(2)S(2), the benzine ring is essentially co-planar with the thia-zole ring, making a dihedral angle of 0.36 (7)°. In the crystal structure, mol-ecules are linked by inter-molecular O-H⋯N hydrogen bonds between the carb-oxy group and the thia-zole N atom into chains along [10]. The chains are assembled into a supermolecular layer structure by thia-zole ring S⋯S contacts [3.5679 (7) Å].

catena-Poly[[(1,10-phenanthroline)copper(II)]-µ-oxalato].

In the title coordination polymer, [Cu(C(2)O(4))(C(12)H(8)N(2))](n), the Cu(II) atom is six-coordinated by four O atoms from two oxalate ligands and two N atoms from one 1,10-phenanthroline (phen) ligand in a distorted octa-hedral coordination geometry. The oxalate anions act as bis-bidentate ligands, bridging the Cu-phen units in zigzag chains extending parallel to [100]. Inter-chain C-H⋯O hydrogen bonding and π-π stacking inter-actions [centroid-centroid distance = 3.7439 (17) Å] assemble neighboring chains, forming a three-dimensional supra-molecular network.

catena-Poly[(µ(2)-3-carb-oxy-5-nitro-benzoato)(µ(3)-5-nitro-benzene-1,3-dicarboxyl-ato)(1,10-phenanthroline)gadolinium(III)].

The crystal structure of the title complex, [Gd(C(8)H(3)NO(6))(C(8)H(4)NO(6))(C(12)H(8)N(2))](n), contains polymeric chains made up of Gd(III) atoms, 1,10-phenanthroline and fully or half-deproton-ated 5-nitro-benzene-1,3-dicarb-oxy-lic acid (H(2)L) ligands. The Gd(III) atom is coordinated in a distorted bicapped trigonal-prismatic fashion by six O atoms from two HL(-) and three L(2-) ligands, and by two N atoms from the 1,10-phenanthroline ligand. The L(2-) ligands bridge the Gd-phenanthroline units, forming chains running parallel to [100]. O-H⋯O hydrogen bonding as well as π-π stacking inter-actions with an inter-planar distance of 3.599 (2) Šassemble neighboring polymeric chains.

Diaqua-bis-(1,10-phenanthroline)nickel(II) tetra-kis-(cyanido-κC)nickelate(II) tetra-hydro-furan solvate monohydrate.

The title complex, [Ni(C(12)H(8)N(2))(2)(H(2)O)(2)][Ni(CN)(4)]·C(4)H(8)O·H(2)O, consists of a cationic [Ni(C(12)H(8)N(2))(2)(H(2)O)(2)](2+) unit, an anionic [Ni(CN)(4)](2-) unit, one uncoordinated water and one tetra-hydro-furan mol-ecule. In the cationic unit, the Ni(2+) atom is coordinated by four N atoms and two O atoms from two 1,10-phenanthroline ligands and two water mol-ecules in a distorted octa-hedral coordination environment. In the anionic unit, the Ni(2+) atom is in a square-planar coordination by four C atoms from four monodentate terminal cyanide ligands. O-H⋯N and O-H⋯O hydrogen bonds link neighboring cationic and anionic units, forming a three-dimensional supra-molecular network. The inter-stitial tetra-hydro-furan mol-ecule is independently disordered over two sites in a 1:1 ratio.