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To solve the problem of the high rising rate and large peak value of the expected current of the short-circuit current in marine DC power system faults, a hybrid DC current limiting circuit breaker scheme based on a high-speed electromagnetic repulsion mechanism is proposed. A parameter selection model is constructed by comprehensively considering the short-time withstand of the thyristor, the volume of the commutation circuit, and capacitor energy, and the optimal value of the commutation circuit parameters at a certain voltage level is obtained. The finite element mathematical model of the high-speed electromagnetic repulsion mechanism is established by coupling the electromagnetic force field, which enables the deformation process of the mechanism under the condition of high acceleration to be considered. The von Mises yield criterion is adopted as the mechanical boundary condition in the design of a high-speed electromagnetic repulsion mechanism, which solves the problem of the long inherent time of opening. The experiment platform is built, and the experiment under the fault condition with a current rising rate of 20 A/μs is completed. The arcing time, commutation time, zero-voltage recovery time, and contact movement characteristics are obtained, which meet the design requirements, verify the effectiveness of the analysis, and lay a solid foundation for further research and development of the current limiting circuit breakers for medium voltage DC systems.

Background Frailty is common in atrial fibrillation(AF)patients, but its related risk factors need to be further investigated. Furthermore, a risk prediction model based on risk factors urgently needed to be established to remind risk among AF patients. Purpose This study aimed to explore the multiple risk factors of frailty in elderly patients with atrial fibrillation(AF) and then construct and validate a nomogram risk prediction model to remind frailty events in this population. Methods A total of 337 hospitalized patients over 60(average age: 69, 53.1% male)with AF in Tianjin Medical University General Hospital from November 2021 to August 2022 were recruited. Patients were assessed for frailty with the FRAIL scale and then assigned into the groups, robust, pre-frail, and frail. The Least absolute shrinkage and selection operator (LASSO) and the Ordinal regression were utilized to screen independent risk factors. Subsequently, gather the factors in a nomogram to predict the risk among the AF population. The concordance index (C-index) and calibration curves were utilized to evaluate the performance of the nomogram model. Results The prevalence of frail and pre-frail were 23.1% and 52.2% among AF patients, respectively. A total of six predictors for frailty were screened out containing age, gender, history of coronary heart disease, number of chronic diseases, sleep disruption, and mental health status. The C-index of internal and external validation for the nomogram model were 0.821(95%CI: 0.778–0.864; bias corrected C-index: 0.795) and 0.837(95%CI: 0.780–0.893; bias corrected C-index: 0.774), respectively, indicating its favourable discriminative ability. Both internally and externally validated calibration charts were highly consistent with the ideal curve, illustrating that the model had a good predictive ability. Conclusion Frailty was common in the AF population, and the nomogram model has a great discriminative and predictive probability which can identify frailty risk incidents in elderly AF patients.

This article points out that the bidirectional power converter based on a linear phase-shifting transformer can be modularized, designed to improve equipment utilization. The analysis of the working status of the bidirectional power flow converter under inverter and rectifier conditions is introduced. The working conditions of the converter in the inverter and rectification state are simulated, and the output voltage and harmonics are analysed. The simulation results show that the system can meet the output index requirements under both inverter and rectification conditions, can be modularized, can reduce the number of components used in the device, and provide strong support for the optimization of subsequent prototypes.

Pulsed power technology gives full play to the characteristics of high pulses in the form of short pulses, and gradually occupies a certain position in industrial applications. It needs to ensure stability and durability while ensuring that the working parameters are met, the switching performance is particularly important., therefore, the reliability study of IGBT power module becomes an inevitable requirement for reliability evaluation in engineering. This article mainly introduces the experimental method of the accelerated aging experiment of IGBT under pulsed power conditions. The electro-thermal simulation is carried out through PLECS and the low-power experimental platform is built to obtain experimental data. Finally, the experimental data is analyzed, and the change rule of the failure characteristic parameters with the aging process under the pulse power condition and the IGBT failure standard different from the typical operating condition are obtained.

Background Stroke has become the leading cause of acquired disability worldwide. Psychological maladjustment and related reactions for stroke disability has subsequently revealed a negative impact on stroke rehabilitation process. Acceptance of disability (AOD) is widely confirmed as a critical factor for psychosocial regulation and disability acceptance. Objective This study aims to investigate acceptance of disability and its influencing factors among stroke patients in China. Methods A total of 220 hospitalized stroke patients were investigated using questionnaire on demographics and disease characters, Adaptation Of Disability Scale-Revised, and other psychological instruments: Medical Coping Modes Questionnaire (MCMQ), Functional Activities Questionnaire (FAQ), Self-Rating Depression Scale (SDS), and Perceived Social Support Scale (PSSS). Results The mean score of AOD is 74.15 (range 32∼128), which reflected a moderate level of disability acceptance among stroke patients in China. Statistical analysis showed that confrontation, the understanding of stroke, self-rating depression, ability of functional activities and family support were major factors affecting acceptance of disability among disabled stroke patients, which explained 49.6% of the total variance. Conclusions In clinical practice, professionals should identify patients with low levels of disability acceptance and explore effective psychological intervention model on the theoretical foundation of different dimensions in AOD theory and related predictors.

A normal-phase enantioselective high-performance liquid chromatographic method was developed for the enantiomeric resolution of naproxcinod, the most advanced cyclooxygenase-inhibiting nitric oxide donator of anti-inflammatory drugs designed for treatment of osteoarthritis. The enantiomers of naproxcinod were resolved on a Chiralpak AD-H (250 × 4.6 mm, 5 μm) column using a mobile phase system containing n-hexane and 2-propanol (95:5, v/v). The resolution between the enantiomers was found to be more than 2.0. The limit of detection and limit of quantitation of (R)-enantiomer were found to be 5 and 15 ng/mL, respectively, for 20 μL injection volume. The sample solution and mobile phase were found to be stable for at least 48 h. The final optimized method was successfully applied to separate (R)-enantiomer from naproxcinod and was proven to be reproducible and accurate for the quantitative determination of (R)-enantiomer in bulk drugs.

A rapid, reliable, and sensitive method for the simultaneous determination of 6 furocoumarins (psoralen, xanthotoxin, bergapten, imperatorin, cnidilin, and isoimperatorin) in Radix glehniae was developed using reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with diode array detection. The HPLC assay was performed on an Ultimate C 18 column (5 μm, 250 mm x 4 mm) with gradient elution of acetonitrile and water within 20 min. The detection wavelength was set at 310 nm. All compounds showed good linearity (r 2 > 0.999). The RSD of intra-day and inter-day variations ranged from 0.2% to 2.7% and 0.3% to 1.7%. The recovery of the assay was in the range of 91.7―107.6%. The method was successfully applied to the simultaneously determination of 6 furocoumarins in Radix glehniae from different areas.

We did a prospective study to investigate the binding of stilbene glucoside (2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside, TSG) to plasma, albumin, and alpha1-AGP (2.0, 10.0, or 50 microg/mL) by three different methods: ultrafiltration, equilibrium dialysis and cloud-point extraction (CPE).Drug stability in plasma was assessed at different temperatures (4, 25, and 37 degrees C) and on the condition of thawing and freezing. A previously validated high-performance liquid chromatography (HPLC) method was used to analyze the total concentration of drug and free fraction in the samples.The binding of TSG to plasma increased with adding drug concentration. The binding to albumin was constant (about 60%) within concentration range studied while the binding to alpha1-AGP decreased with increasing drug concentration indicating that albumin is more important in clinical settings.alpha1-AGP might be important when plasma proteins change with disease. The results to plasma obtained by CPE were in good agreement to those observed by ultrafiltration and equilibrium dialysis, indicating that CPE was a highly sensitive and selective method for the measurement to plasma protein binding of TSG. The results obtained in our studies are important before clinical trials and to perform pharmacokinetic studies.

A novel method, HPLC-MS/MS was developed to qualitatively identify and quantitatively determine the 28 components including 19 diterpenoids, 6 phenolic acids and 3 flavonoids in Isodon rubescens, an important traditional Chinese medicine. The separation was performed on a C(18) column with linear gradient elution with 0.1% aqueous formic acid/methanol containing 0.1% formic acid at a flow rate of 0.7 mL/min. The identification and quantification of those analytes were achieved on a hybrid quadrupole linear ion trap mass spectrometer. Multiple-reaction monitoring scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. Full validation of the method was carried out (linearity, precision, accuracy, LOD and LOQ). The results indicated that the method was simple, rapid, specific and reliable. The proposed method was successfully applied for the qualitative and quantitative analysis of 28 chemical compositions in 21 batches of natural and cultured I. rubescens samples from different sources which had great variation on the contents. The results demonstrated that the method was useful for standardization and differentiation of large numbers of similar samples.

A rapid and simple method has been developed and validated for the determination of m-nisoldipine and its five related substances using micellar electrokinetic capillary chromatography (MEKC). The key factors, including pH, buffer concentration and buffer additive, sodium dodecyl sulfate (SDS) concentration, applied voltage and temperature were systematically investigated in an uncoated fused silica capillary. The total analysis time was less than 9 min. The forced degradation products of m-nisoldipine, which were induced by hydrogen peroxide, acidic and basic conditions, heat and light, were also tested.

A high-performance liquid chromatography coupled with photo diode array detection method is developed for simultaneous determination of seven active components in Qibaomeiran pill, including rutin, 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glycoside, ferulic acid, psoralen, isopsoralen, emodin, and physcion. The analysis is performed on a C(18) column using a mobile phase composed of A (0.1% acetic acid) and B (acetonitrile) with linear gradient elution. Four wavelengths at 245, 290, 320, and 350 nm were chosen as the monitoring wavelength to determine seven active components, respectively. All the compounds show good linearity (r0.999). The developed method is fully validated in respect to precision, repeatability, and accuracy. The proposed method is successfully applied to quantify the seven active components in different Qibaomeiran pill samples. The results indicate that the developed assay could be considered as a suitable quality control method for the Qibaomeiran pill.

A sensitive and specific liquid chromatography-tandem mass spectrometric (LC-MS-MS) method has been developed to determine m-nisoldipine in rat plasma. Sample was pretreated by a single-step protein precipitation with acetonitrile, in contrast to the liquid-liquid procedure frequently used for the extraction of 1,4-dihydropyridines from biologic samples. Separation of analyte and internal standard (I.S.) was performed on a Symmetry RP-C(18) analytic column (50 mm x 4.6 mm, 3.5 microm) with a mobile phase consisting of acetonitrile-water (80:20, v/v) at a flow rate of 0.5 ml/min. The API 4000 triple quadrupole mass spectrometer was operated in multiple reaction monitoring (MRM) scan mode using TurboIonSpray ionization (ESI) source. The method was sensitive with a lower limit of quantification (LLOQ) of 0.2 ng/mL, with good linearity (r>or=0.9982) over the linear range of 0.2-20 ng/mL. All the validation data, such as accuracy, precision, and inter-day repeatability, were within the required limits. The method was successfully applied to pharmacokinetic and relative bioavailability studies of m-nisoldipine polymorphs in rats.

Objective. To discuss the implementation of single disease payment by analyzing the situation of clinical single disease in our hospital. Methods. A total of 710 patients with medical insurance single disease or self-supporting inguinal hernia/femoral hernia in 2011 were retrospectively analyzed. Results. The hospital total cost, medicine fee, surgical anesthesia fee, treatment costs, and other fees of medical insurance inguinal hernia or femoral hernia patients with single disease payment management are all less than that of self-supporting patients. There are statistical differences when p is less than 0.05. The five main factors that affect hospital cost orderly are single disease (self-supporting), general anesthesia, double-sided operation, length of stay and laparoscope. Conclusion. Single disease can effectively control the high-speed growth of one part of disease medical costs, but its further development is limited by defects, such as narrow disease coverage area and so on.

Ethnopharmacological relevance Traditional Chinese medicine (TCM) has been used in clinical practice for several thousand years. TCM has played an indispensable role in the prevention and treatment of diseases, especially the complicated and chronic ones. Pharmacokinetic study on active constituents in herbal preparations is a good way for us to explain and predict a variety of events related to the efficacy and toxicity of TCM. Aim of the study A selective and sensitive HPLC–MS/MS method was first developed and validated for the determination of luteolin, kaempferol, apigenin, quercetol, and isorhamnetin in rat plasma. Materials and methods The LC system consisted of an Agilent Technologies Series 1200 system (Agilent, USA) equipped with an automatic degasser, a quaternary pump, and an autosampler. Chromatographic separations were performed on a Waters SunFire™ C18 column (150 mm × 4.6 mm, 5 μm), and the column temperature was maintained at 25 °C and the sample injection volume was 20 μL. The current LC–MS/MS assay was validated for linearity, intra-day and inter-day precisions, accuracy, extraction recovery and stability. Results The validated method was successfully applied to monitoring the concentrations and pharmacokinetic studies of five flavone compounds in rat plasma after a single oral administration of Verbena officinalis L. extract with a dosage of 8.0 mL/kg. The time to reach the maximum plasma concentration (Tmax1) was 0.48 ± 2.14 h for luteolin, 0.25 ± 0.13 h for kaempferol, 0.97 ± 1.08 h for apigenin, 1.04 ± 4.25 h for quercetol and 0.25 ± 0.16 h for isorhamnetin, and the maximum plasma concentration (Tmax2) was 3.97 ± 1.48 h, 4.05 ± 0.46 h, 4.33 ± 0.58 h, 2.99 ± 0.48 h and 4.02 ± 0.34 h. The elimination half-time (t1/2) of luteolin, kaempferol, apigenin, quercetol and isorhamnetin was 4.02 ± 0.81, 7.65 ± 0.71, 3.30 ± 0.83, 4.55 ± 0.49 and 5.56 ± 1.32 h, respectively. Conclusions This paper described a simple, sensitive and validated LC–MS/MS method for simultaneous determination of luteolin, kaempferol, apigenin, quercetol and isorhamnetin in rat plasma after oral administration of V. officinalis L. extract, and investigated on their pharmacokinetic studies as well, with a short run time of 5 min.

A novel method, HPLC-MS/MS was developed to qualitatively identify and quantitatively determine the 28 components including 19 diterpenoids, 6 phenolic acids and 3 flavonoids in Isodon rubescens, an important traditional Chinese medicine. The separation was performed on a C(18) column with linear gradient elution with 0.1% aqueous formic acid/methanol containing 0.1% formic acid at a flow rate of 0.7 mL/min. The identification and quantification of those analytes were achieved on a hybrid quadrupole linear ion trap mass spectrometer. Multiple-reaction monitoring scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. Full validation of the method was carried out (linearity, precision, accuracy, LOD and LOQ). The results indicated that the method was simple, rapid, specific and reliable. The proposed method was successfully applied for the qualitative and quantitative analysis of 28 chemical compositions in 21 batches of natural and cultured I. rubescens samples from different sources which had great variation on the contents. The results demonstrated that the method was useful for standardization and differentiation of large numbers of similar samples.

A reversed-phase high-performance liquid chromatography method was established for the simultaneous determination of four major constituents, namely myricitrin, hyperin, quercitroside, and quercetin in Folium Rhododendri Micranthi. The optimal conditions of separation and detection were achieved on a C18 analytical column with a gradient mobile phase consisting of acetonitrile and 1% acetic acid at the flow rate of 1.0 mL/min, and detection wavelength was set at 355 nm. All calibration curves showed good linear regression (r > 0.9993) within test ranges. The reproducibility of relative standard deviations was less than 2.3%, and recovery of analytes was greater than 99.4%, respectively. The method was successfully applied to determine the contents of four compounds in Folium Rhododendri Micranthi. The results indicated that the contents of myricitrin, hyperin, quercitroside and quercetin in Folium Rhododendri Micranthi were 0.166%, 0.303%, 0.299%, and 0.053%, respectively.

A high performance liquid chromatography with electrospray tandem mass spectrometry (HPLC–ESI-MS/MS) method has been developed to characterize and quantify 11 coumarin compounds in Radix Angelicae Dahuricae simultaneously. By using this HPLC–ESI-MS/MS method, all 11 coumarins were separated and determined within 10 min. These coumarins were detected by ESI + ionization method and quantified by multiple reaction monitor (MRM). The linear regressions were acquired with r 2 > 0.995, respectively. The precision was evaluated by intra- and inter-day tests, and relative standard deviation (R.S.D.) values were reported within the range of 1.14–4.42% and 0.37–4.00%. The recovery studies for the quantified compounds were observed over the range of 92.1–105.6% with R.S.D. values less than 4.55%. It demonstrated that the method developed was successfully applied for identification and quantification of 11 coumarins in Radix Angelicae Dahuricae . The results showed that the contents of coumarins in Radix Angelicae Dahuricae were processed differently and varied significantly.