Search

A novel UHPLC–MS/MS method with high sensitivity and selectivity for simultaneous detection and chiral resolution of DL-amino acids in beer was established using the newly developed mass spectrometry probe (S)-(3-(4-carboxythiazolidin-3-yl)-3-oxopropyl) diphenylsulfonium (CTOD). The gradient analysis of five chiral amino acids (DL-Asp, DL-Glu, DL-Ala, DL-Pro, and DL-Phe) was carried out on a BEH C18 (2.1 × 150 mm, 1.7 μm) for 30 min with a mobile phase of 0.1% formic acid aqueous solution and 0.1% formic acid methanol/acetonitrile (7:3) solution. The resolutions of DL-amino acids ranged from 1.71 to 5.42. The correlation coefficients were ≥ 0.9994 in the range of 0.25 to 1200 pmol. Meanwhile, limits of detection (LOD) and limits of quantitative (LOQ) analysis were 0.05–0.25 pmol and 0.13–0.50 pmol, respectively. Furthermore, the intra-day and inter-day precision ranged from 0.34% to 6.31%, and the average recoveries ranged from 97.50% to 107.50%. The method was applied to the quantitative analysis and comparison of DL-amino acids in beer samples from 10 different manufacturers, and it was found that the beers were rich in D-amino acids. Four D-AAs including D-Ala, D-Pro, D-Glu, D-Phe (1.9–29.8 μmol L−1) and five L-AAs including L-Pro, L-Ala, L-Phe, L-Glu, L-Asp (5.3–2315.9 μmol L−1) were detected in the beer samples. The average content of L-AAs in the 10 beer samples was significantly higher than that of D-AAs. This study provides a new method for detecting chiral amino acids in beer and reliable data for evaluating the nutritional value of beer. Highlights: We developed a new UHPLC-MS/MS method with high sensitivity and selectivity for the quantification of five DL-amino acids in beer. The analysis of five DL-amino acids in beer by LC-MS is the first report. The method can be used to determine the content of DL-amino acid in beer from different manufacturers. [ABSTRACT FROM AUTHOR]

The ventilation filters from ventilation system in the control area of nuclear power plant will be regularly replaced. In general, the metal frame of the waste filters would not be activated and were expected with a low radiation level, thereby it could be recycled or reused after a systematic clearance assessment. As a regulatory requirement in China, this kind of assessment play a vital role in the radioactive waste management, and a detailed scheme should be established based on long-terms of experience and the unit-specific characteristics. Focus on this, a clearance assessment scheme for the metal frames in nuclear power plants was established in this paper, which would present experience in the radioactive waste management for the nuclear power plant operator and the authorities. [ABSTRACT FROM AUTHOR]

Objective: To observe the clinical effect of high suspension and low incision (HSLI) surgery on mixed haemorrhoids, compared with Milligan-Morgan haemorrhoidectomy. Methods: A multi-centre, randomized, single-blind, non-inferiority clinical trial was performed. Participants with mixed haemorrhoids from Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing Rectum Hospital, Air Force Medical Center of People's Liberation Army of China, and Puyang Hospital of Traditional Chinese Medicine were enrolled from September 2016 to March 2018. By using a blocked randomization scheme, participants were assigned to two groups. The experimental group was treated with HSLI, while the control group was treated with Milligan-Morgan haemorrhoidectomy. The primary outcome was the clinical effect evaluated at 12 weeks after operation. The secondary outcomes included the number of haemorrhoids treated during the operation, pain scores, use of analgesics, postoperative oedema, wound healing, incidence of anal stenosis, anorectal manometry after operation, as well as surgical duration, length of stay and total hospitalization expenses. A safety evaluation was also conducted. Results: In total, 246 eligible participants were enrolled, with 123 cases in each group. There was no significant difference in the clinical effect between the two groups (100.00% vs. 99.19%, P>0.05). Compared with the control group, the number of external haemorrhoids treated during the operation and the pain scores after operation were significantly reduced in the experimental group (P<0.05 or P<0.01); the patient number with wound healing at 2 weeks after operation and the functional length of anal canal at 12 weeks after operation were significantly increased in the experimental group (P<0.05). There was no significant difference in the incidence of anal stenosis, the numbers of patients using analgesics and patients with postoperative oedema between the two groups after operation (P>0.05). The surgical duration and length of stay in the experimental group were significantly longer than those in the control group, and the total hospitalization expense was significantly higher than that in the control group (all P<0.05). No adverse events were reported in either group during the whole trial or follow-up period. Conclusion: HSLI had the advantages of preserving the skin of anal canal completely, alleviating postsurgical pain and promoting rapid recovery after operation. (Registration No. ChiCTR1900022883) [ABSTRACT FROM AUTHOR]

A new simple and sensitive method for the simultaneous detection of free DL-amino acids (DL-AA) in natto was established by UPLC-fluorescence (FL) using the newly developed fluorescence derivatization reagent DBD-trans-2-methyl-L-proline (DBD-M-Pro) by precolumn derivatization. DBD-M-Pro reacts with DL-amino acids at 60 °C for 60 min. Using BEH C18 (2.1 mm × 100 mm, 1.7 μm) column gradient analysis for 20 min, the resolution of diastereomers after the derivatization of four DL-amino acids was 1.65–3.50. The detection limit for amino acids was 0.25–2.5 pmol. The average recovery (%) of DL-amino acids was 86.65–118.70%. The method was applied to the detection of chiral amino acids in natto beans and mucus, and four chiral amino acids, DL-Gln, DL-Asp, DL-Glu, and DL-Ala, were simultaneously detected. At the same time, the DL-amino acid content and D/L ratio of three different manufacturers of natto were compared quantitatively. [ABSTRACT FROM AUTHOR]

The protozoan parasite Giardia duodenalis is known to infect humans and a wide range of animals globally. However, no studies on G. duodenalis infection in Bactrian camels have been reported. In the present study, in order to examine the prevalence and genetic diversity of G. duodenalis in Bactrian camels, 852 fecal samples were collected from 24 sampling sites in three geographical areas (Gansu province, Inner Mongolia, and Xinjiang Uygur autonomous regions) of northwestern China, and subjected to multilocus sequence typing (MLST) analysis targeting the 18S rRNA, β-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) genes. About 84 fecal samples tested positive for Giardia infection, with an overall prevalence of 9.8%, including three samples from camel calves with diarrhea. Significant differences (χ2 = 80.7, df = 2, P < 0.01) in the prevalence were found in Bactrian camels belonging to three geographical areas, with the highest (33.3%) in Gansu province and the lowest (4.2%) in Xinjiang Uygur autonomous region. Furthermore, significantly different prevalences (χ2 = 34.2, df = 2, P < 0.01) were revealed among age groups, with the highest (35.7%) in camels aged 3 to 6 years old, and the lowest (7.5%) in camels aged > 6 years old. Sequence analysis identified two assemblages, including zoonotic assemblage A and ungulate-adapted assemblage E, with the latter as the dominant G. duodenalis assemblage in each age group and at all sampling sites having positive samples except Hotan. Genetic variations were detected among G. duodenalis isolates in these camels, and eight, three, and seven haplotypes were identified at loci bg, gdh, and tpi, respectively, forming two multilocus genotypes (MLGs) of zoonotic assemblage A and one MLG of assemblage E. To the best of our knowledge, this is the first report on G. duodenalis infection in Bactrian camels, and the data indicate that G. duodenalis have a broad host range. [ABSTRACT FROM AUTHOR]

The solubilities and refractive indexes in the NHCl-CaCl-HO system were measured at 50 and 75°C and the phase diagrams were constructed on the basis of the experimental data. The mixing parameters and equilibrium constant K were evaluated using the Pitzer ion-interaction model representations. The results obtained were in good agreement with the experimental data. The mixed parameters of Pitzer ion-interaction model and equilibrium constant obtained in the work can furthermore be applied to solubility predictions of more complicated systems containing NHCl and CaCl. [ABSTRACT FROM AUTHOR]

The current study investigates GaN-based light-emitting diodes (LEDs) with InGaN/GaN/InGaN multi-layer barrier (MLB). Simulation results show that GaN-based LEDs with MLB have better performance than conventional GaN-based LEDs with only one GaN barrier because of the enhancement in hole injection into the quantum well and decrease in electron leakage current. [ABSTRACT FROM AUTHOR]