Design of uncertain displacement controlled velocity control system for hydraulic actuator.

Displacement-controlled systems have high efficiency and are widely used in industry. Accurate control of the actuator motion in hydraulic systems is usually a necessity in industrial applications such as the motion of control surfaces in fixed-wing airplanes for flight control as well as the aircraft brake systems. To address this need, the current study was conducted with the goal of developing a high-fidelity model to achieve precise control. This work focused on modeling a hydrostatic transmission that is used for controlling a linear actuator velocity. The flow entering the actuator was changed using a variable displacement pump. The study included examining the stability and performance of the open-loop system. Additionally, the study involved the design of the proportional-integral-derivative PID and H∞ controllers, followed by the analysis of the stability and performance of the closed-loop system with both controllers. Furthermore, the multiplicative uncertainty is taken into account and the robustness of the system is verified using controllers PID and H∞. In the current study,Uncertain parameters such as actuator efficiency, pump speed, and viscous friction coefficient were considered and allowed for a ±5% deviation from their stated values. Taking uncertainty into account ensures that the system performs properly even in case where the design parameters vary within the specified range. The system response is compared for the cases of open-loop system, closed-loop system with PID controller, and closed-loop system with H∞ controller. The results demonstrated that the open-loop system remains stable for real-world applications but shows insufficient performance in terms of input tracking and disturbance rejection. The introduction of the PID controller significantly enhanced the system's response to a reference input; however, its disturbance rejection capabilities in terms of overshoot and settling time were still unsatisfactory. The system equipped with the PID controller failed to meet the robustness requirements. Conversely, the utilization of H∞ controllers yielded superior responses and fulfilled the robustness criteria.

A bibliometric analysis and visualization of retinopathy of prematurity from 2001 to 2021.

OBJECTIVE: Retinopathy of prematurity (ROP) is an eye disease with the potential to cause blindness, primarily affecting premature infants with low birth weight. This study analyzed the etiology, primary location, and research advances in ROP. MATERIALS AND METHODS: We used bibliometric techniques and searched the Web of Science Core Collection for "retinopathy of prematurity." We found 4,018 original articles and reviews with 69,819 references. We analyzed the data using HistCite (12.03.17), VOSviewer (1.6.16), CiteSpace (6.1. R5), and the Bibliometrix Package (4.1.0). RESULTS: The amount of literature in this area has increased between 2001-2021. An analysis of references and journal co-citations highlights this field's most influential articles and related topics. Hellström, from the University of Gothenburg (Sweden), is the most prolific researcher; Harvard University is the most prolific research institution, and the USA is the most productive country. "Threshold ROP" and "cryotherapy" are the keywords with the highest burst strength. The future research hotspots are artificial intelligence, zone II, ROP development, ranibizumab, and type 1 retinopathy. CONCLUSIONS: This article offers a comprehensive review of the present status of ROP research, along with insights into emerging concepts and potential international collaborations in this field.

Association of oxidative stress and Kashin-Beck disease integrated Meta and Bioinformatics analysis.

OBJECTIVE: To explore the association between oxidative stress (OS) and Kashin-Beck disease (KBD). METHODS: Terms associated with "KBD" and "OS" were searched in the six different databases up to October 2021. Stata 14.0 was used to pool the means and standard deviations using random-effect or fixed-effect model. The differentially expressed genes in the articular chondrocytes of KBD were identified, the OS related genes were identified by blasting with the GeneCards. The KEGG pathway and gene ontology enrichment analysis was conducted using STRING. RESULTS: The pooled SMD and 95% CI showed hair selenium (-4.59; -6.99, -2.19), blood selenium (-1.65; -2.86, -0.44) and glutathione peroxidases (-4.15; -6.97, -1.33) levels were decreased in KBD, whereas the malondialdehyde (1.12; 0.60, 1.64), nitric oxide (2.29; 1.31, 3.27), nitric oxide synthase (1.07; 0.81, 1.33) and inducible nitric oxide synthase (1.69; 0.62, 2.77) were increased compared with external controls. Meanwhile, hair selenium (-2.71; -5.32, -0.10) and glutathione peroxidases (-1.00; -1.78, -0.22) in KBD were decreased, whereas the malondialdehyde (1.42; 1.04, 1.80), nitric oxide (3.08; 1.93, 4.22) and inducible nitric oxide synthase (0.81; 0.00, 1.61) were elevated compared with internal controls. Enrichment analysis revealed apoptosis was significantly correlated with KBD. The significant biological processes revealed OS induced the release of cytochrome c from mitochondria. The cellular component of OS located in the mitochondrial outer membrane. CONCLUSIONS: The OS levels in KBD were significantly increased because of selenium deficiency, OS mainly occurred in mitochondrial outer membrane, released of cytochrome c from mitochondria, and induced apoptotic signaling pathway.

[Risk factors for mortality in pediatric acute respiratory distress syndrome requiring extracorporeal membrane oxygenation support].

Objective: To explore the risk factors for mortality in pediatric acute respiratory distress syndrome (PARDS) requiring extracorporeal membrane oxygenation (ECMO) support. Methods: Clinical data of 109 patients with severe PARDS supported by ECMO, who were hospitalized in 6 ECMO centers in China from September 2012 to February 2020, were retrospectively analyzed. They were divided into survival group and death group according to the prognosis. Chi-square test and rank sum test were used to compare the variables between the two groups, including the demographic data, laboratory examination results, clinical data before and after ECMO, and other supportive treatment. Univariate and multivariate Logistic regression models were used to analyze the prognostic risk factors. Results: In these 109 cases, 54 died and 55 survived. Compared with the survival group, the death group had higher incidences of acute kidney injury (AKI) (48.1% (26/54) vs. 21.8% (12/55), χ²=8.318, P=0.004) and coagulation dysfunction (22.2% (12/54) vs. 7.3% (4/55), χ²=4.862, P=0.027), and higher rate of renal replacement therapy (48.1% (26/54) vs. 21.8% (12/55), χ²=9.694, P=0.008) during ECMO support. Logistic regression analysis showed that continuous renal replacement therapy (CRRT) and AKI were independent risk factors for death in patients with severe PARDS requiring ECMO support (HR=3.88,95%CI 1.04-14.52, HR=4.84,95%CI 1.21-19.46, both P<0.05). Conclusion: AKI and CRRT are independent risk factors for predicting mortality in patients with severe PARDS requiring ECMO support.

[Interfacility transport with extracorporeal membrane oxygenation in pediatric patients: a multicenter study in China].

Objective: To investigate application and safety of pediatric interfacility-transport with extracorporeal membrane oxygenation (ECMO) in China. Methods: The data of 48 patients transported inter-hospital from February 2016 to May 2018 were collected from the following 4 centers: pediatric intensive care unit (PICU) of Bayi Children's Hospital Affiliated to the 7th Medical Center of PLA General Hospital, Pediatric Hospital of Fudan University, Henan Provincial People's Hospital and Children's Hospital of Zhejiang University School of Medicine. The data of patients' characteristics, ECMO mode and wean rate, and mortality were reviewed, which was further compared with the data of 57 compatible inner-hospital ECMO cases with t test, Rank sum test or chi-square test. Results: All the 48 interfacility-transports were accomplished by ambulance on land, with an average transfer distance of (435±422) km. The incidence of ECMO complications was 13% (6 case), without death. There were no significant differences in lactic acid, PaO(2) or SaO(2) before and after transport (4.0 (2.0, 7.5) vs. 3.0 (1.5, 6.0) mmol/L, Z=-1.579, P>0.05; 112(47, 405) vs. 166(122, 240) mmHg (1 mmHg=0.133 kPa), Z=-0.104, P>0.05; 0.97±0.02 vs. 0.96±0.03, t=1.570, P>0.05). Instead, PaCO(2) and pH were significantly different ((47±8) vs. (42±5) mmHg, t=2.687, P<0.05; 7.3±0.2 vs. 7.5±0.2, t=3.379, P<0.05). The total ECMO weaned rate was 73% (35/48) and the survival rate was 67% (32/48). No significant differences in demographic characteristics, ECMO mode or duration, transport distance or duration, or complications existed between the survival group and the death group (7/25 vs. 2/14, χ(2)=0.615, P>0.05; 4/28 vs. 2/14, χ(2)=0, P>0.05; (405±404) vs. (493±465) km, t=0.525, P>0.05; (5±4) vs. (5±5) h, t=0.388, P>0.05; 166 (128, 239) vs. 187(52, 405) h, Z=-0.104, P>0.05; 3/32 vs. 3/16, χ(2)=0.734, P>0.05). The lowest lactate value in survival group before ECMO transport was significantly lower than that in the death group ((5±5) vs. (8±6) mmol/L, t=2.151, P<0.05). There were neither significant differences in age, ECMO mode or support pattern (9/39 vs. 15/42, χ(2)=0.845, P>0.05; 6/42 vs. 7/50, χ(2)=0.001, P>0.05; 29/19 vs. 38/19, χ(2)=0.441, P>0.05), nor in ECMO weaned rate, survival rate or complications between interfacility-transport group and inner-hospital group (35/48 vs. 37/57, χ(2)=0.775, P>0.05; 32/48 vs. 35/57, χ(2)=0.313, P>0.05; 20/48 vs. 22/57, χ(2)=0.102, P>0.05). Conclusion: With appropriate transport equipment and mature teams who handle problems timely during the transport, critically ill children could be safely transported to the destination with ECMO.

[Study on radiation dose in different field of views of oral and maxillofacial cone-beam CT].

Objective: To analyze the absorptive radiation dose of non-target sensitive organs under the NewTomVGi oral and maxillofacial cone-beam CT scanning in different view fields. Methods: The thermoluminescence dosimeter chip was placed in the non-target sensitive organ of the simulated radiology head model, and 6 scanning fields were measured and analyzed (standard resolution: scanning range was 15 cm×15 cm, 15 cm×12 cm, 12 cm×8 cm, 8 cm×8 cm respectively). High definition resolution: the radiation absorption dose of thermoluminescence with the scanning range of 12 cm×8 cm, 8 cm×8 cm, respectively. Results: Under the same resolution, the absorptive dose increased with the expansion of scanning field, and the amount of absorbent during high resolution scanning was higher than that during the standard resolution with the same scanning field. Conclusions: New TomVGi oral and maxillofacial cone-beam CT has sighificant difference in radiation dose in different view fields. The appropriate view field should be selected according to the patient's clinical needs, so as to reduce unnecessary radiation dose during medical imaging examination.

[Four cases of acute respiratory distress syndrome patients transported with veno-venous extracorporeal membrane oxygenation].

Objective: To retrospectively review 4 cases diagnosed with pediatric acute respiratory distress syndrome (ARDS) who were transported with veno-venous (V-V) extracorporeal membrane oxygenation (ECMO) from April 2016 to March 2017. Methods: Four patients were transported to Bayi Children's Hospital Afflicted to the PLA Army General Hospital, with V-V ECMO. Their vital signs, blood-gas analysis and chest X-ray before and after transportation were compared. The length of ECMO, pediatric intensive care unit (PICU) stay and hospitalization, and the prognosis were analyzed. Results: All the four cases were transported to our hospital successfully from distances between 1 000 km to 1 210 km. The 4 cases were 4 to 6 years old with the body weight of 19 to 35 kg, of whom 3 were boys and 1 was girl. The catheters were inserted in the right jugular vein and femoral vein. The vital signs and blood-gas analysis after transportation did not change significantly compared to baseline. The length of ECMO for the four patients were 48, 754, 157 and 438 hours. They stayed in the PICU for 10, 32, 14 and 19 days, respectively. At last, 2 of them were successfully discharged from hospital without any complications; however, the other 2 died of multiple organ failure. Conclusion: Transporting ARDS patients with a satisfactory cardiac function under VV-ECMO by an experienced ECMO team is safe.

[Outcome of pediatric extracorporeal membrane oxygenation in a single center].

Objective: To investigate the application and outcome of pediatric extracorporeal membrane oxygenation (ECMO) in a single center. Methods: The clinical data of 52 pediatric patients with cardiopulmonary failure received ECMO support in Bayi Children's Hospital Affiliated to General Hospital of Beijing Military Command of PLA were collected from January 2012 to October 2016. All patients were divided into two stages by time. January 2012 to December 2014 was stage one. January 2015 to October 2016 was stage two. A retrospective analysis was done for these patients between two stages. In addition, all clinical data were compared with the data of extracorporeal life support organization (ELSO). The constituent ratio differences in different groups were tested by chi square test. Results: In 52 cases, there were 40 boys and 12 girls, aging from 1 day to 7 years, weighing from 2 to 20 kg. There were 35 cases who successfully weaned from ECMO (67%), and 25 cases were able to be discharged alive (48%). In stage one, there were 24 ECMO cases, 18 boys and 6 girls. There were 15 cases successfully weaned from ECMO (63%). Nine patients survived until discharge (38%). Complications were found in 15 cases during ECMO support (63%). In stage two, there were 28 ECMO cases, 22 were boys and 6 were girls. There were 20 cases successfully weaned from ECMO (71%). Sixteen patients survived until discharge (57%). Complications were found in 12 cases during ECMO support (43%). There was no significant difference in survival rates between two stages. However, the neonatal survival rate was higher in stage two than in stage one (71% (12/28) vs. 31% (5/24), χ(2)=5.107, P=0.038). The proportion of respiratory support was higher in stage two than in stage one (50% (14/28) vs. 21% (5/24), χ(2)=4.741, P=0.029), while the proportion of extracorporeal cardiopulmonary resuscitation (ECPR) decreased significantly (21% (6/28) vs. 67% (16/24), χ(2)=10.835, P=0.001). Application of peritoneal dialysis treatment in stage two was higher (6 vs. 0 cases, χ(2)=8.097, P=0.025). Mortality of ECMO was still higher than that of ELSO (48% (25/52) vs. 62% (34 655/55 886), χ(2)=4.281, P<0.05). The constituent ratio of different types of support varied between ECMO and ELSO patients (χ(2)=19.562, P<0.001). Conclusions: ECMO technology can provide effective support for severe cardiopulmonary failure in critically ill children. Due to the multidisciplinary nature of ECMO technology, the complexity and characteristics of pediatric patients, it takes long time to improve ECMO management and prognosis.

Clinical analysis of cases of neonatal Streptococcus agalactiae sepsis.

With the advent of antibiotic resistance, pathogenic bacteria have become a major threat in cases of neonatal sepsis; however, guidelines for treatment have not yet been standardized. In this study, 15 cases of neonatal Streptococcus agalactiae sepsis from our hospital were retrospectively analyzed. Of these, nine cases showed early-onset and six cases showed late-onset sepsis. Pathogens were characterized by genotyping and antibiotic sensitivity tests on blood cultures. Results demonstrated that in cases with early-onset sepsis, clinical manifestations affected mainly the respiratory tract, while late-onset sepsis was accompanied by intracranial infection. Therefore, we suggest including a cerebrospinal fluid examination when diagnosing neonatal sepsis. Bacterial genotyping indicated the bacteria were mainly type Ib, Ia, and III S. agalactiae. We recommend treatment with penicillin or ampicillin, since bacteria were resistant to clindamycin and tetracycline. In conclusion, our results provide valuable information for the clinical treatment of S. agalactiae sepsis in neonatal infants.

Clinical significance of CD44 expression in children with hepatoblastoma.

The aim of this study was to investigate the expression of CD44 and its clinical significance in children suffering from hepatoblastoma (HB). CD44 expression was detected with immunohistochemistry staining in 30 samples from hepatoblastoma children and 10 normal liver tissue samples from normal children. The data obtained was statistically analyzed using the chi-square test, using the SPSS (v.11.0) software. The rate of CD44 expression was significantly higher (66.7%) in hepatoblastoma tissues than in normal liver tissues (χ(2) = 4.848, P < 0.05). The rate of CD44 expression was significantly higher in children with stage III or IV hepatoblastoma (83.3%) than that in children with stage I and II hepatoblastoma (χ(2) ＝ 5.625, P < 0.05) (41.7%). Therefore, CD44 expression might play an important role in the pathogenesis, progression, and prognosis of HB in children.

Meta-analysis demonstrates association of the TGF-ß1 gene -C509T polymorphism with susceptibility to IgA nephropathy in European but not in Asian populations.

There are conflicting reports associating the TGF-ß1 gene -C509T polymorphism with susceptibility to IgA nephropathy. We investigated this association through a meta-analysis. Case-control studies were searched up to January 2012; the genotype frequencies in the control group were found to be consistent with Hardy-Weinberg equilibrium. Publication bias was tested by funnel plot and the Egger regression test. Eight studies, comprising 1364 cases and 1483 controls, were included. Significant heterogeneity was observed (χ² = 18.29, P = 0.01). Under the random-effects model, the overall odds ratio (OR) was 1.01 [95% confidence interval (95%CI) = 0.74-1.38; P = 0.94]. In the subgroup analysis based on ethnicities, no significant effect was observed in the Asian descent groups (five comparisons, OR = 0.78; 95%CI = 0.53-1.15; moderate heterogeneity between studies). However, an association was observed in the European descent groups (OR = 1.5; 95%CI = 1.15-1.96; P = 0.003; no significant heterogeneity between studies). There was no evidence of publication bias according to funnel plot and the Egger regression test (a = -2.16, P = 0.23). There was heterogeneity between studies and no clear evidence of an association between the TGF-ß1 gene -C509T polymorphism and susceptibility to IgA nephropathy in the worldwide population. Subgroup analysis suggests that the TGF-ß1 gene -C509T polymorphism would not be a risk factor for IgA nephropathy in Asians but might play a role in Europeans. More studies are required for definitive conclusions.

Critical role of c-Kit in beta cell function: increased insulin secretion and protection against diabetes in a mouse model.

AIMS/HYPOTHESIS: The receptor tyrosine kinase, c-Kit, and its ligand, stem cell factor, control a variety of cellular processes, including pancreatic beta cell survival and differentiation as revealed in c-Kit ( Wv ) mice, which have a point mutation in the c-Kit allele leading to loss of kinase activity and develop diabetes. The present study further investigated the intrinsic role of c-Kit in beta cells, especially the underlying mechanisms that influence beta cell function. METHODS: We generated a novel transgenic mouse model with c-KIT overexpression specifically in beta cells (c-KitßTg) to further examine the physiological and functional roles of c-Kit in beta cells. Isolated islets from these mice were used to investigate the underlying molecular pathway of c-Kit in beta cells. We also characterised the ability of c-Kit to protect animals from high-fat-diet-induced diabetes, as well as to rescue c-Kit ( Wv ) mice from early onset of diabetes. RESULTS: c-KitßTg mice exhibited improved beta cell function, with significantly improved insulin secretion, and increased beta cell mass and proliferation in response to high-fat-diet-induced diabetes. c-KitßTg islets exhibited upregulation of: (1) insulin receptor and IRSs; (2) Akt and glycogen synthase kinase 3ß phosphorylation; and (3) transcription factors important for islet function. c-KIT overexpression in beta cells also rescued diabetes observed in c-Kit ( Wv ) mice. CONCLUSIONS/INTERPRETATION: These findings demonstrate that c-Kit plays a direct protective role in beta cells, by regulating glucose metabolism and beta cell function. c-Kit may therefore represent a novel target for treating diabetes.

[Expression and characterization of human pulmonary surfactant-associated protein A1 in Saccharomyces cerevisiae].

The cDNA encoding pulmonary surfactant-associated protein A1 (SP-A1) derived from healthy adult's lung was cloned into the pVT102U/alpha, expression vector of Saccharomyces cerevisiae, which contains the yeast alpha-factor signal sequence, leading to the secretion of expressed protein, and then transformed into Saccharomyces cerevisiae S-78 (leu2, ura3, rep4) by electroporation. After 2-3 days culture in adequate pH, the expressed SP-A1 accumulated up to 400 mg/L in supernatant. The pure proteins were obtained by Sephadex G-25, G-75, Sepharose 4B. The expressed recombinant products, 62 kD and 32 kD, reacted to specific antibody using ELISA and Western blot. The SP-A1 protein expressed in Saccharomyces cerevisiae was efficient in enhancing the phagocytosis of E. coli J5 by alveolar macrophages.

[The experimental study on protective effects and its mechanisms of interleukin-1 receptor antagonist on isolated swine kidney with ischemia/reperfusion].

AIM: To observe the protective effects and approach its mechanisms of interleukin-1 receptor antagonist (IL-1ra) on the isolated swine kidney with ischemia/reperfusion (IR). METHODS: Thirty two swine were divided randomly into control group (n = 11), IR group (n = 11) and IL-1ra treatment group (IL-1ra group, n = 10) in the study. All swine were electrified. The kidneys were removed and put in ice-box immediately for detecting in control group. In IR group and IL-1ra group, reperfusion pressure and flow rate were both observed once every 30 minutes, the urine at the time of reperfusion 2 hours and the renal cortex at the time of reperfusion 2 hours and 30 minutes were taken for detecting. RESULTS: The resistance of perfusion in IL-1ra group was much lower than that in the IR group during reperfusion except start of reperfusion, there was a significant difference between IR group and IL-1ra group (P < 0.05, under the same). The content of MDA,TNF-alpha and IL-8 in the renal cortex in IR group were higher and the activities of SOD and Na(+) -K(+) -ATPase were lower than those in control group, In IL-1ra group, the content of MDA and the activity of SOD in renal cortex was respectively higher or lower than that in control group. Compared with IR group, the content of MDA and TNF-alpha and IL-8 in the renal tissues and urine protein were lower and the activities of SOD and Na(+) -K(+) -ATPase were higher in IL-1ra group. The serious degeneration and necrosis of renal tissue were observed in IR group under light microscope and electron microscope, but there was only slight degeneration in IL-1ra group. CONCLUSION: The results indicated that IL-1ra were effective in protecting the isolated swine kidney from IR injury.

Spatial stability of extracellular potassium ion and blood flow distribution in rat cerebral cortex after permanent middle cerebral artery occlusion.

Extracellular potassium ion activity ([K+]o) increases precipitously during brain ischemia when blood flow falls below threshold values less than approximately 15 mL/100 g/min. This flow threshold for increase of [K+]o occurs also in focal ischemia producing gradient from ischemic core to adjacent normally perfused brain. In this study we investigated the spatial and temporal stability of extracellular potassium ion and blood flow gradients after permanent middle cerebral artery occlusion (MCAO) in rats. [K+]o and regional CBF were measured, respectively, with K+-sensitive and polarographic hydrogen-sensitive microelectrodes at different cortical locations in the middle cerebral artery distribution region. Spatial assessment of [K+]o and regional CBF was conducted at 30, 90, and 180 minutes after MCAO. [K+]o in the more lateral cortex (core) increased from near 3 mmol/L before MCAO to greater than 50 mmol/L and was associated with flow values less than 25% of pre-ischemic levels. Measurements medial to the core (penumbra) indicated progressively decreasing levels of [K+]o and improvement of CBF. There was a tendency for [K+]o in penumbral zones to decrease toward normal levels with time, but there was little dissipation of [K+]o in core regions. In contrast, the spatial CBF profile remained remarkably constant for the entire recording period. Thus, unlike infarction which has been reported to expand with time after focal ischemia, the spatial [K+]o disturbance tends to contract primarily due to decreasing [K+]o with time in the penumbra. Thus, steady state levels of [K+]o after focal ischemia may not be a valuable predictor of cell viability.