[Adsorption Performance and Mechanism of Oxytetracycline in Water by KOH Modified Biochar Derived from Corn Straw].

The pollution control of tetracycline antibiotics in the environment has become a hot topic, and biochar adsorption has become an important technology to remove organic pollutants. Pyrolytic biochars (BC400, BC500, and BC600) were prepared from corn straw and then were modified by KOH to obtain KBC400, KBC500, and KBC600. Among them, KBC400 was selected for secondary pyrolysis activation at 400-600℃ to obtain AKBC400, AKBC500, and AKBC600. The structure characteristics and surface properties of AKBC were also characterized. The adsorption kinetics and thermodynamic characteristics of oxytetracycline hydrochloride (OTC) in the solution by AKBC were investigated using batch experiments. Compared to that of BC400, the specific surface area and pore structure of AKBC were significantly improved, and the aromaticity was also enhanced, resulting in the notable enhancement of the adsorption capacities for OTC. The pseudo-second-order kinetics model could better fit the adsorption process, and AKBC500 had the largest adsorption rate constant and capacity. Both the intraparticle diffusion and film diffusion were the rate-limiting steps. The Langmuir, Freundlich, and Temkin models could fit the adsorption isotherms perfectly. The adsorption of OTC on AKBC was a spontaneous, endothermic, and entropy-increasing process by both physisorption and chemisorption. The pH values in the range of 3.0-7.0 were favorable for the adsorption of OTC by AKBC. The adsorption capacity decreased with the humic acid concentration over 10 mg·L-1. The adsorption mechanism of OTC by AKBC involved pore filling, hydrogen bonding, π-π conjugation, cation-π bond, and strong electrostatic effect. AKBC still had good reusability for OTC removal after five times of regeneration. The obtained AKBC is a potential adsorbent for OTC removal from water due to the good pore structure, high adsorption capacity, and stable adsorption effect.

Two porous Ni-MOFs based on 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine showing solvent determined structures and distinctive sorption properties toward CO2 and alkanes.

By regulating the solvent used for synthesis, two porous Ni-MOFs, namely {[Ni3(BTC)2(TPT)2/3(H2O)4.08(MeOH)0.92]·2DMF·0.5H2O·0.5MeOH}n (1) and {[Ni3(BTC)2(TPT)2(H2O)6]·6DMF}n (2) (H3BTC = 1,3,5-benzenetricarboxylic acid, TPT = 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine, DMF = N,N-dimethylformamide, and MeOH = methanol) were obtained. Compound 1 reveals a rigid 3D framework, while compound 2 shows a flexible 3-fold interpenetrated framework. Compound 1 exhibits a selective adsorption of CO2 due to the sieving effect of the rigid framework containing two types of cages with small apertures. Noteworthily, the flexible compound 2 displays an obviously guest-induced structural transformation. The desolvated compound 2 reveals a much higher capacity toward CO2 and n-C4H10 than those of N2 CH4, C2H6 and C3H8.

Laparoscopic Common Bile Duct Exploration Versus Open Approach in Cirrhotic Patients with Choledocholithiasis: A Retrospective Study.

OBJECTIVE: To evaluate the safety and benefits of laparoscopic common bile duct exploration (LCBDE) compared with open approach (OCBDE) in cirrhotic patients. MATERIALS AND METHODS: Between January 2009 and December 2012, a total of 113 cirrhotic patients with choledocholithiasis underwent common bile duct (CBD) explorations in our department. There were two groups of patients: A:LCBDE (n = 61) and B:OCBDE (n = 52). Patients' demographic characteristics, surgical data, postoperative outcomes, and long-term results were retrospectively collected and analyzed. RESULTS: There were no significant differences between the two groups in the demographic characteristics or preoperative status. The transcystic approach was successfully performed in 52 (46.0%) patients (group A:34, group B:20), whereas choledochotomy was successful in 59 (54.0%) patients (group A:27, group B:32). The differences between group A and group B in terms of surgical time (124.9 ± 34.2 minutes versus 132.6 ± 48.6 minutes, P = .323), stone clearance rate (93.4% versus 94.2%, P > .05), short-term complication rate (9.8% versus 13.4%, P = .547), and recurrent stone rate (6.6% versus 5.8%, P > .05) were not statistically significant. However, group A suffered less blood loss [95 (60-200) mL versus 200 (90-450) mL, P < .001] and shorter length of hospital stay (4.7 ± 2.5 days versus 11.3 ± 3.1 days, P < .001) than group B. In the LCBDE group, 4 (6.6%) patients were converted due to heavy inflammation and severe adhesions. No mortality, biliary injury, or stricture occurred during follow-up. CONCLUSION: LCBDE can be safely performed in patients with Child-Pugh A or B cirrhosis and choledocholithiasis, with considerable efficiency, minimal short-term complications, and acceptable long-term outcomes. LCBDE has the advantages over open CBD exploration of less bleeding and reduced length of hospital stay.

Ultrasensitive mercury(II) ion detection by europium(III)-doped cadmium sulfide composite nanoparticles.

With the biomolecule glutathione (GSH) as a capping ligand, Eu(3+)-doped cadmium sulfide composite nanoparticles were successfully synthesized through a straightforward one-pot process. An efficient fluorescence energy transfer system with CdS nanoparticles as energy donor and Eu(3+) ions as energy accepter was developed. As a result of specific interaction, the fluorescence intensity of Eu(3+)-doped CdS nanoparticles is obviously reduced in the presence of Hg(2+). Moreover, the long fluorescent lifetime and large Stoke's shift of europium complex permit sensitive fluorescence detection. Under the optimal conditions, the fluorescence intensity of Eu(3+) at 614 nm decreased linearly with the concentration of Hg(2+) ranging from 10 nmol L(-1) to 1500 nmol L(-1), the limit of detection for Hg(2+) was 0.25 nmol L(-1). In addition to high stability and reproducibility, the composite nanoparticles show a unique selectivity towards Hg(2+) ion with respect to common coexisting cations. Moreover, the developed method was applied to the detection of trace Hg(2+) in aqueous solutions. The probable mechanism of reaction between Eu(3+)-doped CdS composite nanoparticles and Hg(2+) was also discussed.

Synchronous fluorescence determination of mercury ion with glutathione-capped CdS nanoparticles as a fluorescence probe.

Glutathione (GSH)-capped CdS nanoparticles was successfully synthesized in aqueous solutions at room temperature. Based on the characteristics of synchronous fluorescence spectroscopy (SFS), a simple method with high sensitivity and selectivity was developed for determination of Hg(2+) with GSH-capped CdS nanoparticles as a fluorescence probe. The maximum synchronous fluorescence is located at 335 nm, scanning with excitation and emission wavelengths of 260 and 440 nm (Delta lambda=lambda(em)-lambda(ex)=180 nm), respectively. Under optimal conditions, the quenched fluorescence intensity increased linearly with the concentration of Hg(2+) ranging from 0.15 x 10(-7) to 125 x 10(-7) mol L(-1). The limit of detection was 4.5 x 10(-9) mol L(-1). Compared with several fluorescence methods, the proposed method exhibited several merits in terms of its linear range and the sensitivity. The quenching mechanism was also discussed. Moreover, analytical application of the method was demonstrated by water samples.

Ultrasensitive determination of silver ion based on synchronous fluorescence spectroscopy with nanoparticles.

Based on the characteristics of synchronous fluorescence spectroscopy (SFS), a new method with high sensitivity and selectivity was developed for rapid determination of silver ion with functional cadmium sulphide (CdS) nanoparticles as a fluorescence probe. When Delta lambda (lambda(em) - lambda(ex)) = 215 nm, maximum synchronous fluorescence is produced at 304 nm. Under optimal conditions, functional cadmium sulphide displayed a calibration response for silver ion over a wide concentration range from 0.8x10(-10) to 1.5x10(-8) mol L(-1). The limit of detection was 0.4x10(-10) mol L(-1) and the relative standard deviation of seven replicate measurements for the lowest concentration (0.8x10(-10) mol L(-1)) was 2.8%. Compared with several fluorescence methods, the proposed method had a wider linear range and improved the sensitivity. Furthermore, the concentration dependence of the synchronous fluorescence intensity is effectively described by a Langmuir-type binding isotherm.