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Background We aimed to determine the prevalence and risk factors of surgical site infection (SSI) after cesarean delivery (CD) in a rural area in China. Methods We identified 155 patients with incisional and organ/space SSIs by International Classification of Disease codes and matched them with 465 patients (controls) in a time-matched retrospective quality assurance analysis. Multiple logistic regression analyses were performed to examine the risk factors for SSI: the work-years of providers, the number of antenatal care (ANC) visits, CD after labor, positive discharge culture, postoperative C-reactive protein (CRP) levels and fever. Results and discussion: During the study, 155 women with SSI were identified among the 8640 patients who delivered by CD. The incidence of SSIs was 179 per 10 000patients (95%CI: 151–207 per 10 000 patients). The total duration of hospitalization in patients with SSI was 14.49 ± 8.68 days compared with 7.96 ± 2.35 days in patients with no SSI (P < 0.01). Multiple logistic regression analysis showed that the work-years of providers (odds ratio [OR] = 3.729, 95% confidence interval [CI]: 1.463–9.501, p = 0.006), irregular ANC visits (OR = 3.245, 95% CI: 1.264–8.329, p = 0.028), CD after labor (OR = 2.545, 95% CI: 0.935–6.926, p = 0.020), postoperative CRP level (OR = 2.545, 95% CI: 0.935–6.926, p = 0.016) and a positive discharge culture (OR = 2.954, 95% CI: 0.305–28.643, p = 0.019) were positively associated with SSI. However, the rates of maternal request (OR = 0.186, 95% CI: 0.065–0.535, p = 0.002) and postoperative fever (OR = 0.208, 95% CI: 0.087–0.494, p = 0.001) were negatively related to SSI. Conclusions Special attentions should be paid to CD patients who had irregular ANC visits, attempted labor, a positive discharge culture, higher CRP levels and fever after surgery, who had a greater risk of SSI.

AIM: To explore the ocular features of corona virus disease (COVID)-19 and severe acute respiratory syndrome coronavirus (SARS-CoV)-2 detection in tears and conjunctival scrapes in non-severe COVID-19 patients. METHODS: This is a multicenter observational clinical study with no intervention conducted from Jan 25th to March 1st, 2020. Clinical data and samples of tears and conjunctival scraping were collected in consecutive laboratory-confirmed, non-severe COVID-19 patients from three hospitals. COVID-19 virus was analyzed by real-time reverse transcriptase polymerase chain reaction (RT-PCR) kits. RESULTS: Totally 255 laboratory-confirmed, non-severe COVID-19 patients were recruited for ocular manifestation investigation. Of them, 54.9% were females, with a mean age of 49.4y. None of the patients has evidence of uveitis; 11 patients (4.3%) complained of mild asthenopia; 2 (0.8%) had mild conjunctival congestion and serous secretion. Twenty-five of them had performed tears and conjunctival scrape for COVID-19 virus detection, with 4 yield possible positive results in the nucleoprotein gene. One of them were asymptomatic with normal chest CT and positive pharyngeal swab result. CONCLUSION: Ocular manifestations are neither common nor specific in non-severe COVID-19 patients. Meanwhile, COVID-19 virus nucleotides can be detected in the tears and conjunctival scrape samples, warranting further research on the transmissibility by the ocular route.

It is worth noting that an increasing number of international students, especially Chinese students, have been flooding into English-speaking countries such as the United Kingdom, the United States or Australia in pursuit of advanced knowledge and better academic environments. As ESL students are enrolling in writing courses in colleges and universities, teachers are confronted with problems that non-native speakers bring to the class when it comes to their academic writing. The problems are more serious than they appear to be. For one thing, according to Reid (1993: 774), there is a dramatic difference between native students and ESL students in ‘the needs, backgrounds, learning styles, and writing strategies’. For another, the situation becomes worse due to ‘considerable diversity even among ESL students in terms of language and cultural backgrounds, prior education, gender, age, and ESL language proficiency’ (Reid, 1993: 774). Although there is not a single solution which is effective in solving complex ESL issues, teachers would be in a better position to understand their ESL students' writing problems if they were to learn about the distinct nature of L2 writing shaped by linguistic and cultural differences. In this article, the author, who was once a Chinese ESL student in the USA and is now an EFL teacher in China, explores how English writing differs from Chinese writing and how these differences lead to Chinese ESL students' difficulty with English writing. This article is expected to increase ESL practitioners' awareness of the urgency for them to recognize and deal with these differences in order to teach L2 writers effectively, to treat them fairly and thus provide them with equal opportunities to achieve academic and professional success.

Under high-speed rotation, the retainer-slipper assembly has serious collision interference, which affects the performance of the key friction pair of the piston pump. And abnormal wear of the retainer and slipper is observed in the faulty piston pump, even with fracture of the retainer and severe wear of the slipper neck. Based on the master-slave principle of the slipper and the retainer, a mathematical model of the relative motion relationship between the slipper-retainer is established. And the collision law between the slipper and the retainer is obtained by combining the relative motion velocity equation of the slipper. The effects of swashplate angle and pump shaft speed on the relative motion trajectory and collision strength of the slipper-retainer assembly are analyzed. The coordinates of all contact points between the slipper and the retainer during one piston cycle are calculated. These results clearly show the friction area of the retainer hole. Researches show that the rotation angle of the power slipper at the transition point is reduced with increasing swashplate angle. The increase of pump shaft speed has no influence on the contact law of the assembly. The collision strength of the assembly increases with the swashplate angle and pump shaft speed. A parametric investigation of the contact and collision between the slipper and the retainer is realized, providing a design method for analyzing the wearing character and mechanical properties of the axial piston pump.