An improved IPT-PLL technology for single-phase grid-connected inverters in complex power grid conditions.

Aiming at the common problems of frequency variations and harmonics in complex power grids, an improved inverse Park transform phase locked loop (IPT-PLL) technology for single-phase converters suitable for micro grid systems is proposed. Firstly, in the phase detection of PLL, the α component of Park transformation is selected as the reference voltage, and its orthogonal component is constructed using a 1/4 fundamental period delay method. Secondly, Lagrange interpolation polynomials are introduced to approximate fractional delay to solve the problem of delay calculation errors caused by frequency changes. Thirdly, in order to compensate for the poor ability of traditional proportional integral (PI) regulators, multi resonant controllers are superimposed to suppress low order harmonic disturbances. Finally, the design method and system performance of the PI regulator and each resonant controller are analyzed theoretically. The experimental results show that the proposed improved IPT-PLL method has strong adaptability to complex power grids. It can significantly improve the tracking performance of power grid frequency, suppress the interference of low order harmonics and DC bias. And it has good dynamic and static performance.

Upcycling harmful algal blooms into short-chain organic matters assisted with cellulose-based flocculant.

Upcycling harmful algal blooms (HABs) into short-chain organic matters (SCOMs) presents a significantly underexplored opportunity for addressing environmental concerns and achieving circular economy. But there are challenges of low HABs harvesting and SCOMs conversion efficiencies. To address these issues, a novel cellulose-based flocculant derived from abundant agricultural waste (wheat straw) was developed. This flocculant possesses high surface positive charge to aggregate negatively charged microalgae cells via charge neutralization mechanism, resulting in HABs harvesting efficiency of 97 %. Moreover, the flocculant can serve as a carbon to nitrogen (C/N) regulator to optimize the harvested slurry properties for downstream fermentation. Following hydrothermal pretreatment for one hour, the HABs-flocculant slurry was effectively converted into SCOMs with a total energy output of 64.3 kJ/L and energy conversion efficiency of 67 %, in which SCOMs was major contributor (92 %). This work may inspire eco-friendly and cost-effective approach for HABs disposal with extra benefits of SCOMs production.

Compared with other methods, cyanoacrylate and lauromacrogol in treating esophagogastric varices did not increase the risk of postoperative infection.

BACKGROUND: Patients with cirrhosis commonly undergo endoscopic cyanoacrylate injection for gastric and esophageal variceal bleeding. However, postoperative infections can increase the risk of rebleeding and mortality. AIM: This study aimed to determine the risk of postoperative infections and its associated factors following cyanoacrylate injection treatment in these patients. METHODS: A retrospective analysis was conducted on 57 patients treated with ligation (ligation group), 66 patients treated with cyanoacrylate injection (injection group), and 91 patients treated with conservative treatment (control group) at the Nanchong Central Hospital. RESULTS: The rate of postoperative infection was similar among the cyanoacrylate, ligation, and conservative treatment groups, with no significant statistical difference observed (P = 0.97). Multivariate analysis identified postoperative Child-Pugh score and renal insufficiency as two independent risk factors for postoperative infection. The rebleeding rate in the injection group was significantly lower than in the other groups (P = 0.01). Mortality was significantly higher in the control group compared with the ligation and injection groups (P = 0.01). CONCLUSION: Cyanoacrylate combined with lauromacrogol injection did not significantly increase the risk of infection compared with ligation and conservative treatments, and it was more effective in reducing the risk of rebleeding. This method is safe, effective, and holds clinical value for broader application.

Antibiotic prophylaxis vs. on­demand antibiotic treatment in endoscopic therapy for variceal hemorrhage: A meta­analysis of randomized controlled trials.

The aim of the present study was to conduct a meta-analysis for elucidating the effects of antibiotic prophylaxis on infection, rebleeding and mortality in patients who underwent endoscopic therapy for variceal hemorrhage. Articles on antibiotic prophylaxis and on-demand antibiotic administration following endoscopic therapy for acute variceal bleeding were searched on PubMed, Embase and Cochrane Library between January 1959 and February 2024, to elucidate whether the use of prophylactic antibiotics was necessary. The quality of randomized controlled trials (RCTs) was assessed using the Cochrane risk-of-bias assessment tool and RevMan software version 5.4.1 was used for meta-analysis of the data. The current meta-analysis included four RCTs and 322 patients with acute variceal bleeding who underwent endoscopic therapy. All included studies were of high quality according to the Cochrane risk-of-bias assessment tool. According to the results of the meta-analysis, the incidence of infection in the prophylactic antibiotic group was significantly lower than that in the on-demand group [odds ratio (OR), 0.31; 95% confidence interval (CI), 0.13-0.74; P=0.009]. The prophylactic antibiotic group also exhibited a lower incidence of rebleeding compared with that of the on-demand group (OR, 0.37; 95% CI, 0.19-0.72; P=0.003). No significant differences were noted in the incidence of mortality between the two groups (OR, 0.92; 95% CI, 0.45-1.92; P=0.83). In conclusion, the data indicated that antibiotic prophylaxis is recommended to be used in patients who have undergone endoscopic therapy for variceal hemorrhage.

Effectiveness of 13-valent pneumococcal conjugate vaccine against vaccine-serotype community acquired pneumococcal diseases among children in China: A test-negative case-control study.

BACKGROUND: In 2016, China licensed 13-valent pneumococcal conjugate vaccine (PCV13) based on a study that demonstrated its immunogenicity is non-inferior to PCV7. However, the real-world effectiveness of PCV13 against vaccine-serotype pneumococcal diseases in China has limited evidence. METHODS: A test-negative case-control study was conducted among children under 5 years old admitted to the Children's Hospital of Soochow University (SCH) with respiratory tract infections from January 2018 to December 2020. Cases were defined as children from whom the isolates were tested positive for Streptococcus pneumoniae (S. pneumoniae) with serotypes included in PCV13. Two control groups were included, one represented children with isolates positive for S. pneumoniae of non-PCV13 serotypes and the other comprised children who tested negative for S. pneumoniae. The S. pneumoniae-negative controls were selected by matching them to the cases based on gender, age and admission date in a 1:1 ratio. Vaccine effectiveness (VE) was calculated using a logistic regression model as (1- adjusted odds ratio) * 100 %. RESULTS: A total of 2371 pneumococcal isolates were included in the analysis, of which 75.0 % (1779/2371) were covered by PCV13 serotypes. Consequently, these 1779 children were classified as cases, and 592 children were designated as non-PCV13 serotype controls. Another 1779 children were correspondingly recruited as S. pneumoniae-negative controls. Overall, 40 cases (2.3 %) and 148 controls (6.2 %) had received vaccination. The overall VE in the PCV13/non-PCV13 serotypes case-control study was 50.0 % (95 % CI: 15.0, 70.7), which was lower than the VE of 74.4 % (95 % CI: 60.7, 83.3) in the matched PCV13/S. pneumoniae-negative case-control study. VE was higher for ≥ 2 or ≥ 3 doses of vaccination compared to ≥ 1 dose. VE against specific PCV13 serotypes (6B, 6A and 19F) was higher than for other serotypes. CONCLUSIONS: PCV13 vaccination demonstrates effectiveness against vaccine-serotype pneumococcal diseases in children, particularly for serotypes 6B, 6A and 19F.