Burst Pressure Prediction of Subsea Supercritical CO2 Pipelines

To improve transportation efficiency, a supercritical CO₂ pipeline is the best choice for large-scale and long-distance transportation inshore and offshore. However, corrosion of the pipe wall will occur as a result of the presence of free water and other impurities present during CO₂ capture. Defects caused by corrosion can reduce pipe strength and result in pipe failure. In this paper, the burst pressure of subsea supercritical CO₂ pipelines under high pressure is investigated. First, a mechanical model of corroded CO₂ pipelines is established. Then, using the unified strength theory (UST), a new burst pressure equation for subsea supercritical CO₂ pipelines is derived. Next, analysis of the material’s intermediate principal stress parameters is conducted. Lastly, the accuracy of the burst pressure equation of subsea supercritical CO₂ pipelines is proven to meet the engineering requirement by experimental data. The results indicate that the parameter b of UST plays a significant role in determining burst pressure of pipelines. The study can provide a theoretical basis and reference for the design of subsea supercritical CO₂ pipelines.     

我国放射卫生学学科建设与放射卫生工作回顾

随着人们对电离辐射对人类健康危害的认识,以及随之开展的电离辐射生物效应及防护措施的研究,逐步形成了放射卫生学。因此作为传统的公共卫生体系下的五大卫生之一,放射卫生主要围绕电离辐射对人体健康有害影响及其综合防护措施开展工作。从上世纪三、四十年代起,经过近百年的蓬勃发展,现阶段我国的放射卫生学学科水平和放射卫生工作成效等有了很大提升。本文就放射卫生学研究与我国放射卫生工作的历史、现状、工作内容等情况进行简单的概述,以期为我国放射卫生工作今后的发展提供助力。     

Moderate Hypofractionated Helical Tomotherapy for Older Patients with Localized Prostate Cancer: Long-term Outcomes of a Phase I–II Trial

BackgroundOur previous study showed that two different regimens of moderate hypofractionated radiotherapy (HFRT) delivered with helical tomotherapy (HT) are well tolerated in older prostate cancer patients. We provide a longterm efficacy and toxicity after > 7 years of follow-up.Patients and methodsThe study recruited 33 patients from February 2009 to July 2011 (76 Gy/34F; Group-1); and 34 from July 2011 to February 2014 (71.6 Gy/28F; 50.4 Gy/25F for the risk of pelvic lymph nodes involvement (LNI) >15%; Group-2). The primary outcomes were biochemical failure (BF), biochemical failure and clinical disease failure (BCDF), progression-free survival (PFS), overall survival (OS), late genitourinary (GU) and gastrointestinal (GI) toxicity.ResultsThe average ages of two groups were 80 and 77 years and the proportions of patients with LNI > 15% were 69.7% and 73.5%, respectively. At the final follow-up in February 2020, 27.3% and 20.6% cases experienced BF, with a median time until BF of 3.3 years. A total of 38.8% patients reached primary endpoints, in which 18 deaths were reported BCDF events (45.5% vs. 32.4%, p = 0.271). There was no significant difference in 7-year PFS (68.6% vs. 74.8%, p = 0.591), BCDF (45.5% vs. 32.4%, p = 0.271) and OS (71.9% vs. 87.5%, p = 0.376) for full set analysis and for subgroup analysis (all p > 0.05). The incidence of grade ≥ 2 late GU (6.2% vs. 6.3%, p = 0.127) and GI toxicities (9.4% vs. 15.6%, p = 0.554) was comparable.ConclusionsIn older patients with localized prostate cancer, two moderate hypofractionated regimens were all well tolerated with similar, mild late toxicities and satisfactory survival, without necessity of prophylactic pelvic node irradiation.Key words: helical tomotherapy, radiation dose hypofractionation, progression-free survival, follow-up studies, prostatic neoplasms, adenocarcinoma     

软组织损伤超声治疗研究现状

尽管超声广泛用于治疗软组织损伤,而且超声的生物物理学效应通过体外研究也得以证实,但超声对软组织损伤的治疗效果仍受到质疑。很少有确切的证据表明超声治疗软组织损伤有效,其原因可能与多种因素有关,如技术方面的变数,临床研究中方法学的局限与缺陷,或者超声确实缺少治疗作用。     

Anticholinergic treatment for sialorrhea in children: A systematic review

BackgroundSialorrhea in children can be associated with adverse physical and social effects. Treatment using anticholinergic medications has been shown to offer symptomatic relief, but there is no consensus regarding which treatment is the most efficacious.ObjectiveTo examine the effectiveness of anticholinergic medications for sialorrhea in children.MethodsA systematic review was carried out in Medline, EMBASE, Cochrane, Scopus, and the Web of Science from inception until April 29, 2020. Studies reporting original data on the efficacy of anticholinergic medications in the management of sialorrhea in children aged 0 to 17 years of age were included. This review adhered to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) standards. Data on study design, setting, population, pharmacologic intervention(s), comparator(s), outcomes, and results were extracted and summarized.ResultsThe search strategy identified 2,800 studies of which 27 articles were included in the synthesis, including five randomized controlled trials. Each anticholinergic undergoing experimental study (glycopyrrolate, scopolamine/hyoscine, trihexyphenidyl/benzhexol, benztropine, and atropine) showed evidence of efficacy. Adverse side effects were common. Significant heterogeneity exists in the studies’ methodology and the variability of outcome measures used between studies precluded a meta-analysis.ConclusionsGlycopyrrolate, scopolamine/hyoscine, trihexyphenidyl/benzhexol, benztropine, and atropine have all shown efficacy in the treatment of sialorrhea in children. The small number of reports and the variability in study design precluded a meta-analysis. More studies are needed with uniformity in outcome measures to help guide evidence-based decision making. A guidance table is presented.     

Ruthenium-catalyzed asymmetric hydrogenation of aromatic and heteroaromatic ketones using cinchona alkaloid-derived NNP ligands

A series of cinchona alkaloid-based NNP ligands, including a new one, have been employed for the asymmetric hydrogenation of ketones. By combining ruthenium complexes, various aromatic and heteroaromatic ketones were smoothly reacted, yielding valuable chiral alcohols with extremely high 99.9% ee. Moreover, a proposed reaction mechanism was discussed and verified by NMR.

A series of cinchona alkaloid-based NNP ligands including a new one has been employed for the asymmetric hydrogenation of ketones. By combining ruthenium complexes, various ketones were smoothly reacted with up to 99.9% ee.

Since the well-known failure of using racemic thalidomide, attention has been paid to the manufacture of optically pure compounds as effective components in pharmaceuticals and agrochemicals. Asymmetric hydrogenation of ketones, especially heteroaromatic ketones, has emerged as a popular facile route to approach enantiopure secondary alcohols as essential intermediates for the construction of biologically active molecules.^1–4 Knowles et al.⁵ pioneered the production of enantioenriched chiral compounds in 1968, and Noyori and co-workers^6–8 laid the cornerstone of asymmetric hydrogenation in 1990s. Subsequently, numerous catalytic systems have been developed. Ru-BICP-chiral diamine-KOH was developed and proved to be effective for asymmetric hydrogenation of aromatic ketones by Xumu Zhang.⁹ Cheng-yi Chen reported asymmetric hydrogenation of ketone using trans-RuCl₂[(R)-xylbinap][(R)-daipen] and afforded secondary alcohol in 92–99% ee.¹⁰ Mark J. Burk and Antonio Zanotti-Gerosa disclosed Phanephos-ruthenium-diamine complexes catalyzing the asymmetric hydrogenation of aromatic and heteroaromatic ketones with high activity and excellent enantioselectivity.¹¹ Qi-Lin Zhou et al. designed and synthesized chiral spiro diphosphines as a new chiral scaffold applied in the asymmetric hydrogenation of simple ketones with extremely high activity and up to 99.5% ee.^12–15 Similarly, Kitamura and co-workers have developed a set of tridentate binan-Py-PPh₂ ligands for the asymmetric hydrogenation of ketones affording excellent results.¹⁶ Recently, chiral diphosphines and tridentate ligands based on ferrocene have been developed for the asymmetric hydrogenation of carbonyl compound with a remarkable degree of success.^17–21 Despite many ligands for asymmetric hydrogenation of ketones have been reported, expensive reagent and multistep complicated reactions were employed to synthesize most of them.^22–24 In light of increasing industrial demand, easily obtained, cheap and practical chiral ligands are still highly desirable. In addition to chiral ligands, the selection of metals was essential for asymmetric hydrogenation.^25–27 Although Mn,^28–30 Fe,^31–34 Co,^35–37 Ni^38,39 and Cu^40,41 metals were proved to be effective for asymmetric hydrogenation in recent years, Rh,^42–44 Ir^45,46 and especially Ru remained the most preferred metals. Ruthenium^47–51 was chosen owing to its superior performances in terms of low price, selectivity and activity. Takeshi Ohkuma,⁵² Hanmin Huang^53,54 and Johannes G. de Vries⁵⁵ all successfully used ruthenium catalysts for asymmetric hydrogenation of ketones. Admittedly, there is a continuing interest in the development of cheaper, simpler and more efficient catalysts for the asymmetric hydrogenation of ketones under mild conditions to access corresponding secondary alcohols. Recently, we developed new NNP chiral ligands derived from cinchona alkaloid for the asymmetric hydrogenation of various ketones in extremely excellent results using a iridium catalytic system.⁵⁶ Prompted by these encouraging results, we were interested in exploring a ruthenium-catalyzed asymmetric hydrogenation of ketones with NNP chiral ligands derived from cinchona alkaloid. Here, we showed that changing from iridium to ruthenium, with the same simple synthetic ligands, delivered a catalyst catalyzed asymmetric hydrogenation of ketones to give the industrially important chiral alcohols with up to 99.9% ee. Although the catalytic activity of ruthenium catalyst was not as high as that of the iridium catalyst, the enantioselectivity could be maintained, and even showed higher enantioselectivity in the hydrogenation of some substrates.Chiral tridentate ligand NNP (L1–L10) were synthesized and characterized as reported in our previous publication. With tridentate ligands in hand, we began to evaluate the catalytic performance in benzylidene-bis(tricyclohexylphosphine) dichlororuthenium-catalyzed asymmetric hydrogenation of acetophenone employed as a standard substrate (Fig. 2). MeOH was found to be a better one as the conversion and enantioselectivity were 99.9% and 98.2%, respectively. Bases screening showed that Ba(OH)₂ was superior to the others, giving >99.9% conversion and 98.8% ee in the present catalytic system (Fig. 1). Ligand screening revealed that the configuration of chiral centers of cinchona alkaloids of the ligand markedly affected the catalytic performance. NNP ligands derived from cinchonine and quinidine appeared to benefit both the reaction rate and enantioselectivity, while those derived from cinchonidine and quinine had the opposite effect. Further, different NNP ligands that bearing different substituents on the phenyl rings were evaluated. Similar to our previous research, ligands with electron-withdonating substituents showed better catalytic performance than those with electron-withdrawing substituents. However, it was noted that the more electron-withdonating substituents furnished lower activity but same enantioselectivity. The optimal ligand L5 derived from quinidine with one methoxy group on benzene ring provided the corresponding chiral alcohol with 99.9% conversion and 98.8% ee. Considering that L3 derived from cinchonine had similar catalytic performance to L4 derived from quinidine, new ligand L10 similar to L5 with one methoxy group on benzene ring was synthesized and applied to the asymmetric hydrogenation of template substrate. 99.6% conversion and 97.6% ee was obtained. Hence, L5 was employed as better ligand in subsequent experiments.Open in a separate windowFig. 1The effect of different bases for the asymmetric hydrogenation of acetophenone (substrate/Ru/L5 = 500/1/2, ketones: 0.429 mol L⁻¹, base: 0.15 mol L⁻¹, MeOH: 2 mL, 30 °C, 6 MPa, 2 h.).Open in a separate windowFig. 2The effect of different solvents for the asymmetric hydrogenation of acetophenone. (substrate/Ru/L5 = 1000/1/2, ketones: 0.858 mol L⁻¹, Ba(OH)₂: 0.15 mol L⁻¹, solvent: 2 mL, 30 °C, 6 MPa, 2 h.).The effect of different ligand for the asymmetric hydrogenation of acetophenone^a

阿司匹林在心血管系统疾病中的应用

近年来,随着人民生活水平的提高和生活方式的转变,心血管系统疾病逐渐成为对生命和生活质量威胁最大的疾病.1999年美国心脏协会专家预测,2010～2020年冠心病致死率将在全球排名第一,且平均发病年龄逐渐提前,我们正面临前所未有的挑战.     

A rare case of isolated accessory mitral tissue in an asymptomatic adult female

Accessory mitral valve tissue (AMVT) is a rare congenital cardiac anomaly, which is associated with other congenital heart diseases. It is diagnosed in neonates or childhood and rarely in adulthood. Nevertheless, AMVT is an incidental finding or described as isolated. Echocardiography, especially three-dimensional echocardiography is considered as an optimal imaging technique for AMVT diagnosis. We herein presented an asymptomatic adult AMVT cases with significant left ventricular outflow tract obstruction and surgical excision was recommended.     

Gastroduodenal intussusception caused by gastric gastrointestinal stromal tumor in adults: a case report and literature review

Intussusception mostly occurs in childhood and is rare in adults. Although intussusception can occur in any part of the gastrointestinal tract, gastroduodenal intussusception caused by a gastric tumor is relatively uncommon in clinical practice. A PubMed search identified 24 published cases of gastroduodenal intussusception caused by gastric gastrointestinal stromal tumor (GIST); however, it is possible that we missed other cases not included in PubMed. Here we report a case of gastroduodenal intussusception caused by gastric GIST in an 85-year-old man. He came to the hospital because of recurrent black stools. Plain computed tomography (CT) scan indicated a mass in the gastric antrum, with slight enhancement in the arterial phase on enhanced CT scan. He was diagnosed with GIST. In addition, images indicated that the mass overlapped into the duodenum, and gastroduodenal intussusception was thus considered. Gastroscopy showed a huge mass in the gastric body. According to the gastroscopy and CT results, gastroduodenal intussusception caused by a gastric tumor was considered. The patient underwent complete surgical removal, which revealed a mass originating from the gastric antrum and overlapping into the duodenum. The postoperative pathological diagnosis was intermediate-risk gastric GIST. The patient was followed up for 4 months without tumor recurrence.     

Can health technology assessments assist the global campaign against poverty?

Although a key tenant of the Sustainable Development Goals is to achieve universal health coverage,the global drug gap persists—over a third of the global popul...