Search

A method of headspace-solid-phase microextraction-gas chromatography/triple quadrupole mass spectrometry was established for simultaneous determination of 10 types of 51 odorous substances in water. The effects of extraction head, extraction temperature, extraction time, salt content, desorption time and split ratio on detection results were investigated with optimized gas chromatography-mass spectrometry parameters using the multiple reaction monitoring (MRM) mode for triple quadrupole mass spectrometry. The results showed that the optimized conditions were polydimethylsiloxane/divinylbenzene as extraction head, 55 ℃ as extraction temperature, 20 min as extraction time, 300 g/L NaCl as salt content, desorption time of 0.5 min and the split ratio of 10∶1. The detection limits of 51 odorous substances ranged from 0.4 to 183 ng/L, and the linear correlation coefficients were greater than 0.995. The detection limits of indicator substances, such as geosmin, 2-methylisothiol, anisole, dimethyl disulfide, and dimethyl trisulfide were 0.4, 0.9, 1.9, 3.5, 1.7 ng/L, respectively, which met the limit requirement of “Standard for Drinking Water Quality (GB 5749—2022)” of China. The spiked recoveries of the low, medium and high concentration levels were 76.2%-118%, 78.9%-119% and 82.0%-119%, and the relative standard deviations were 2.9%-19.4%, 1.8%-13.4% and 0.9%-13.2%, respectively. This method was used to detect the odorous substances in 29 surface waters, in which 12 odorous substances such as methyl mercaptan, dimethyl sulfide, and DL-sec-butyl acetate were detected with the concentration range of 2.2~1 651 ng/L. There were no apparent interferences in the MRM channels for the detected odorous substances. This method has the characteristics of simple pretreatment, good reproducibility and high accuracy, which is suitable for simultaneous and rapid screening of various types of odorous substances in water bodies.

Objective: This study aimed to improve the utilization value of scallop processing by-products, by analyzing the antioxidant activity of its protein hydrolysates. Methods: The processing by-products of Argopecten irradians were used as raw materials, and the proteins were extracted by alkali extraction and acid precipitation, alkali extraction and ammonium sulfate precipitation and low temperature ethanol denaturation precipitation. Then the proteins were analyzed by SDS-PAGE. Pepsin, flavourzyme, dispase and alcalase were used to hydrolyze the protein, and the antioxidant activities of the hydrolysate products were analyzed. The molecular weight distribution, amino acid composition and hydroxyproline content of dispase hydrolysates were further analyzed. Results: The purity of protein obtained by alkaline ammonium sulfate precipitation method was the highest, reaching 91.16%, with the optima electrophoretic results. All the four hydrolysates had DPPH, ABTS, hydroxyl radical scavenging ability and reducing ability, and the dispase hydrolysate showed the highest antioxidant ability, especially hydroxyl radical scavenging rate, which reached （77.24±1.87）%. The hydrolysate of dispase contained 15 kinds of amino acids such as aspartic acid, with a total content of 84 g/100 g, and the content of hydroxyproline reached （11.82±0.09）%. Conclusion: The protein obtained from the by-products of scallop processing by alkaline extraction and ammonium sulfate precipitation, and its dispase hydrolysates have optimal antioxidant activity and high nutritional value, which can be further developed as antioxidant functional food.

Gastric tube placement is a common clinical procedure. During the catheterization process, the gastric tube may enter the trachea by mistake, presenting symptoms such as choking, dyspnea, cyanosis and so on. Occasionally, patients have atypical symptoms, which are easily ignored in clinical practice, bringing great safety risks to the operation. This paper reported a case of gastric tube misplacement into the trachea using tetracaine gel as lubricant before gastrointestinal surgery, analyzed the causes and summarized the preventive and nursing measures, and reviewed the new methods, new techniques and relatively rare complications of gastric tube placement. The lubricant with anesthetic effect should be used carefully when placing gastric tube. The application of new technology can improve the success rate of gastric tube placement. (安置胃管是常见的临床操作。在置管过程中, 胃管可能会误入气管, 表现为呛咳、呼吸困难、发绀等症状, 偶有患者症状不典型, 存在安全隐患。现报告1例应用丁卡因胶浆置管过程中胃管误入气管且无典型症状的病例, 分析原因并总结预防护理措施, 并结合文献对安置胃管的新方法、新技术及相对罕见的并发症进行总结。 安置胃管时使用带有麻醉作用的润滑剂需谨慎, 新技术的应用可提高安置胃管的成功率。)

For post-menopausal women, stroke is complicated by the variable effects of estrogen therapy and the age-related therapeutic consequences involved. Estrogen therapy has been shown to have an age-dimorphic effect, which is neuroprotective in young females, but non-neuroprotective, even neurotoxic in acyclic females. We hypothesized that arterial baroreflex (ABR) and its downstream acetylcholine-α7 nicotinic acetylcholine receptor (α7nAChR) anti-inflammatory pathways are involved in estrogen efficacy toward cerebral ischemic damage. Our data showed that estrogen supplements contributed to ABR improvement and neuroprotection in adult, not aged, ovariectomized (OVX) rats. In adult rats, OVX-induced estrogen deficiency aggravated middle cerebral artery occlusion (MCAO), which induced brain infarction and reduced ABR function, with decreased α7nAChR expression of the brain and exaggerated inflammation following MCAO; these effects were significantly prevented by supplementation with estrogen. ABR impairment by sinoaortic denervation partly attenuated the estrogen effect on baroreflex sensitivity (BRS) and ischemic damage in adult rats, as well as α7nAChR expression and inflammatory response. These data suggested that ABR and acetylcholine-α7nAChR anti-inflammatory pathways are involved in the neuroprotection of estrogen in adult OVX rats. In contrast, aged rats exhibited more severe ischemic damage and inflammatory response than adult rats, as well as poorer baroreflex function and lower α7nAChR expression. Estrogen supplements did not improve BRS or confer neuroprotection in aged rats without affecting brain α7nAChR and post-ischemic inflammation. Most importantly, ketanserin restored ABR function and significantly postponed the onset of stroke in aged female strokeprone spontaneously hypertensive rats, whereas estrogen treatment failed to delay the development of stroke. Our findings reveal that estrogen is protective against ischemic stroke (IS) in adult female rats and that ABR played a role in this beneficial action. Dysfunction of ABR and unresponsiveness to estrogen in aged female rats may contribute to a reduced estrogen efficacy against cerebral ischemia.

ObjectiveTo study the relationship between water temperature and floating time of aquatic cadavers， providing a reference for more precise positioning and searching for floating corpses.MethodsThe floating model of guinea pig after drowning at 17-30 ℃ was established, and the floating times of carcasses were recorded. The collected data of 32 floating corpse cases in the Pearl River were sorted out and analyzed according to the floating time of corpses corresponding to each degree of water temperature. The relationship models between water temperature and the floating time of guinea pig carcass, and between that and the floating time of real cases were established.ResultsThe floating time of the cadaver was negatively correlated with water temperature. The power function fitting equation of the relationship between floating time and water temperature of guinea pig carcass was y=1×1015x-10.530（R2=0.871, P

Objective: To explore the major compound in Polygonati Rhizoma (Huang Jing, 黄精) for quality control. Methods: The major compound was isolated and analyzed by liquid chromatography-mass spectrometry (LC-MS), and subsequently further identified by nuclear magnetic resonance (NMR). Thin layer chromatography (TLC) was optimized based on the previous methods reported in the Chinese Pharmacopeia (2015 edition). Results: The major compound was isolated from the natural material and identified as linoleic acid. A high performance liquid chromatography (HPLC) method with robust linearity (R2 = 0.999 7), specificity, precision, stability, repeatability and recovery was developed for linoleic acid determination. TLC chromatogram was improved significantly after optimization for qualitative analysis. Conclusions: The optimized TLC method is practical and can be adopted for quality control of Polygonati Rhizoma (Huang Jing, 黄 精 ). The levels of linoleic acid vary between species of Polygonati Rhizoma (Huang Jing, 黄 精 ), with Polygonatum cyrtonema Hua (Jiang Xing Huang Jing, 姜型黄精) showing the highest contents. This study provides valuable information for quality control of Polygonati Rhizoma (Huang Jing, 黄精).

BackgroundIrritable bowel syndrome is a functional gastrointestinal disease. Evidence has suggested that probiotics may benefit IBS symptoms. However, clinical trials remain conflicting.AimsTo implement a systematic review and meta-analysis of clinical trials regarding the efficacy and safety of probiotics for IBS patients.MethodsWe searched for relevant trials in Medline(1966 to Jan 2019), Embase(1974 to Jan 2019), the Cochrane Central Register of Controlled Trials(up to Jan 2019), the ClinicalTrials.gov trials register(up to Jan 2019), and Chinese Biomedical Literature Database(1978 to Jan 2019). Risk ratio (RR) and a 95% confidence interval (CI) were calculated for dichotomous outcomes. Standardized mean difference (SMD) and 95% CI were calculated for continuous outcomes.ResultsA total of 59 studies, including 6,761 patients, were obtained. The RR of the improvement or response with probiotics versus placebo was 1.52 (95% CI 1.32–1.76), with significant heterogeneity (I2 = 71%, P < 0.001). The SMD of Probiotics in improving global IBS symptoms vs. Placebo was -1.8(95% CI -0.30 to -0.06), with significant heterogeneity (I2 = 65%, P < 0.001). It was impossible to draw a determinate conclusion. However, there were differences in subgroup analyses of probiotics type, dose, treatment duration, and geographic position. Probiotics seem to be safe by the analysis of adverse events(RR = 1.07; 95% CI 0.92–1.24; I2 = 0, P = 0.83).ConclusionProbiotics are effective and safe for IBS patients. Single probiotics with a higher dose (daily dose of probiotics ≥1010) and shorter duration (< 8 weeks) seem to be a better choice, but it still needs more trials to prove it.

Based on the inside and outside area of the enterprises, this paper re-constructs the double-layer responsibility control system of enterprise environmental cost (DRSEC) by referring to life cycle theory, responsibility center theory and system theory. In the inner layer, each responsibility center of environmental cost control is divided according to the five stages of the enterprise life cycle. These responsibility centers closely cooperate to effectively reduce the environmental costs of the enterprises. In the outer layer, the two major responsible entities of the government and the public supervise the control of environmental costs, guide the goals setting of environmental costs and give feedback to inner layer. By designing a double-layer environmental cost control system with synchronous operation of inner and outer layers, we expect to provide new ideas for enterprises to control environmental costs.

Due to their adverse health effects and their abundance in urban areas, diesel exhaust ultrafine particles caused by the aftertreatment devices have been of great concern in the past years. An experiment of particles number emissions was carried out on a high-pressure, common rail diesel engine with catalytic diesel particle filter (CDPF) to investigate the impact of CDPF on the number emission characteristics of particles. The results indicated that the conversion rates of CDPF is over 97%. The size distributions of particles are bimodal lognormal distributions downstream CDPF at 1400 r/min and 2300 r/min. CDPF has a lower conversion rates on the nucleation mode particles. The geometric number mean diameters of particles downstream CDPF is smaller than that upstream CDPF.