A chiral porous organic polymer COP-1 used as stationary phase for HPLC enantioseparation under normal-phase and reversed-phase conditions.

A spherical chiral porous organic polymer (POPs) COP-1 is synthesized by the Friedel-Crafts alkylation reaction of Boc-3-(4-biphenyl)-L-alanine (BBLA) and 4,4'-bis(chloromethyl)-1,1'-biphenyl (BCMBP), which was used as a novel chiral stationary phase (CSPs) for mixed-mode high-performance liquid chromatography (HPLC) enantioseparation. The racemic compounds were resolved in normal-phase liquid chromatography (NPLC) using n-hexane/isopropanol as mobile phase and reversed-phase liquid chromatography (RPLC) using methanol/water as mobile phase. The COP-1-packed column exhibited excellent separation performance toward various racemic compounds including alcohols, amines, ketones, esters, epoxy compounds, organic acids, and amino acids in NPLC and RPLC modes. The effects of analyte mass and column temperature on the separation efficiency of racemic compounds were investigated. In addition, the chiral resolution ability of the COP-1-packed column not only can be complementary in RPLC/NPLC modes but also exhibit a good chiral recognition complementarity with Chiralpak AD-H column and chiral porous organic cage (POC) NC1-R column. The relative standard deviations (RSD) (n = 5) of the retention time, resolution value, and peak area by repeated separation of 1-(4-chiorophenyl)ethanol are all below 3.0%. The COP-1 column shows high column efficiency (e.g., 17,320 plates m-1 for 1-(4-chlorophenyl)ethanol on COP-1 column in NPLC), high enantioselectivity, and good reproducibility toward various racemates. This work demonstrates that chiral POPs microspheres are promising chiral materials for HPLC enantioseparation.

A chiral metal-organic cage [Fe4L6](ClO4)8 used for capillary gas chromatographic separations.

Metal-organic cages (MOCs), as a promising class of crystalline porous materials with well-defined cavities, have attracted wide attention due to their multifarious potential applications in gas storage, host-guest chemistry, molecular recognition, separation, catalysis, sensing, and drug delivery and so on. Herein, we report that a chiral MOC [Fe4L6](ClO4)8 coated capillary column was fabricated for high-resolution gas chromatographic separation of various analytes, including n-alkanes, n-alcohols, positional isomers, aromatic hydrocarbon mixture, especially for racemic compounds. A series of racemic compounds such as alcohols, epoxides, aldehydes, ketones, ethers, esters, alkenes, sulfoxides and amino acid derivatives could be well separated on the [Fe4L6](ClO4)8 coated capillary column with high enantioselectivity and good reproducibility. Comparing the chiral resolution ability of the MOC [Fe4L6](ClO4)8 coated column with the commercial ß-DEX 120 column and the porous organic cage (POC) CC10 coated column, the chiral MOC column can be complementary to the two different types of columns. The results show that the chiral MOC [Fe4L6](ClO4)8 exhibited excellent separation performance toward a wide range of organic compounds, which will be very attractive as a new chiral separation media and has potential application prospects in separation science.

Superficial chiral etching on an achiral metal-organic framework for high-performance liquid chromatography enantioseparations.

Chiral metal-organic frameworks have shown great potential in enantioselective separation and asymmetric catalysis due to their diverse and adjustable structures with abundant chiral recognition sites. Herein, a new chiral post-synthetic modification was used for preparing an achiral@chiral metal-organic frameworks core-shell composite [Cu3 (Btc)2 ]@[Cu2 ((+)-Cam)2 Dabco] by a superficial chiral etching method. The [Cu3 (Btc)2 ]@[Cu2 ((+)-Cam)2 Dabco] composite was utilized as a novel chiral stationary phase for HPLC enantioseparation. Various racemates were separated on the [Cu3 (Btc)2 ]@[Cu2 ((+)-Cam)2 Dabco]-packed column (column A). It exhibited good chiral resolving ability toward many different kinds of racemates, especially chiral drugs. Among them, the highest resolution value for 1,2-diphenyl-1,2-ethanediol reaches 2.70. The relative standard deviations of retention time and peak area for repeated separation of 1,2-diphenyl-1,2-ethanol were 0.45% and 0.81%, respectively. Compared with the resolution ability of [Cu2 ((+)-Cam)2 Dabco]-packed column (column B), column A shows higher column efficiency and better separation performance than those of column B. The results indicated that the [Cu3 (Btc)2 ]@[Cu2 ((+)-Cam)2 Dabco] as a stationary phase can greatly improve the column efficiency and chiral resolution ability of chiral metal-organic frameworks, which demonstrated that the superficial chiral etching as an economic and efficient strategy opens up a new way for the application of metal-organic frameworks.

Bile reflux is an independent risk factor for precancerous gastric lesions and gastric cancer: An observational cross-sectional study.

OBJECTIVE: To identify whether bile reflux on endoscopy and other related variables are risk factors for precancerous gastric lesions and gastric cancer (GC). METHODS: A multicenter, cross-sectional and observational study was conducted in five centers in China from June to October 2019, 1162 patients were recruited and divided into the chronic gastritis (CG), the precancerous lesion (low-grade intraepithelial neoplasia and intestinal metaplasia), and GC groups (including high-grade intraepithelial neoplasia). All participants underwent detailed interviews, endoscopy and biopsy, and completed questionnaires. Odds ratio and 95% confidence interval were calculated with multivariate logistic regression models with or without adjustment for Helicobacter pylori infection. RESULTS: We recruited 668 patients with CG, 411 with precancerous lesions and 83 with GC. By comparing the CG and precancerous lesion groups, independent risk factors for cancerous gastric lesions were the grade of bile reflux, patient's age, dietary habits and family history of GC. Similar results were obtained when comparing the CG and GC groups. In addition, bile reflux was confirmed as an independent risk factor for progression from precancerous lesions to cancer. CONCLUSIONS: Bile reflux on endoscopy as well as age, dietary habits and a family history of GC were independent risk factors for the development of precancerous gastric lesions and GC.

Influence of serum vitamin D level on Helicobacter pylori eradication: A multi-center, observational, prospective and cohort study.

OBJECTIVES: This study was designed to test whether serum vitamin D levels affected Helicobacter pylori (H. pylori) infection and eradication rates. METHODS: A multicenter observational prospective cohort study was conducted. A total of 496 H. pylori- positive (H. pylori+ ) and 257 H. pylori-negative (H. pylori- ) patients were enrolled from four hospitals in China. Baseline serum vitamin D levels were measured and a 13 C-urea breath test (UBT) was performed for all the participants. The H. pylori+ patients were divided into two subgroups based on their serum vitamin D levels (<10 or ≥10 ng/mL). A second 13 C-UBT was performed between 4 and 8 weeks after 14-day bismuth-containing quadruple eradication therapies. Factors potentially affecting H. pylori eradication were determined using a questionnaire survey. RESULTS: Serum vitamin D levels were significantly lower in the H. pylori+ group than in the H. pylori- group ([17.0 ± 6.9] ng/mL vs [19.2 ± 8.0] ng/mL, P = 0.000). H. pylori eradication rate significantly differed between patients with serum vitamin D levels of <10 ng/mL and ≥10 ng/mL (71.7% vs 87.3%, P = 0.005). A multivariate analysis showed that having serum vitamin D level ≥10 ng/mL was an independent risk factor for a successful H. pylori eradication (odds ratio 0.381, 95% confidence interval 0.183-0.791, P = 0.010). CONCLUSIONS: Serum vitamin D level may affect H. pylori infection and its eradication. Randomized controlled trials are needed to find out whether vitamin D supplements may increase the H. pylori eradication rate.

[The melioration on spectra response heterogeneity of hadamard transform spectral imager].

Hadamard transform optics has been developed in the past decades. It has been used in distinguishing targets, detecting feeble signals and so on. Hadamard transform spectral imager (HTSI), based on digital micro-mirror device, is a new dispersion spectral imager. HTSI has been developed in our laboratory. The spectral heterogeneity of encoded image captured by HTSI has been researched according to spectrum calibration in this paper. Relative and absolute spectrum emittance calibration algorithms have been proposed first time on HTSI to meliorate the spectrum heterogeneity. It aims at the problem that the accuracy of recovered spectrum is depressed by the heterogeneity noise and disorder encoding spectrum in spectral image. Simulation and experiment result have demonstrated that the meliorated spectral curve is close to the standard spectrum, and the variance of the recovered spectrum ranges from 2.4% to 4.2% with regard to the spectral image of 7 waves. This is fully satisfied for the requirement of laboratory and projects.