Due to the fixed and limited sampling period in the real-time system, three-phase permanent-magnet synchronous machine (PMSM) drives using switching-table-based direct torque control (ST-DTC) usually ...suffer from steady-state error and ripple of torque. For the case of the dual three-phase system that has been widely investigated recently, the harmonic currents inevitably occur, which can be regarded as the third issue. This harmonic currents lead to the increase of losses and the decrease of system efficiency. Previous literature has addressed the aforementioned issues but only deals with either the torque ripple issues or harmonic currents. Therefore, this paper first introduces two types of synthetic vectors, which can reduce the harmonic currents effectively, as well as the most suitable switching sequences. Then, a modified five-level torque regulator has been proposed to improve the torque performance. With the proposed method, not only the harmonic currents have been suppressed, but also the steady-state error and ripple of torque can be considerably reduced, whereas the merits of classical ST-DTC, such as simple structure and excellent dynamic performance, are preserved. The experimental results validate the effectiveness of the proposed strategy.
Varied causative and risk factors can lead to cardiac dysfunction. Cardiac dysfunction often evolves into heart failure by cardiac remodeling due to autonomic nervous system disturbance and ...neurohumoral abnormalities, even if the detriment factors are removed. Renal sympathetic nerve activity plays a pivotal regulatory role in neurohumoral mechanisms. The present study was designed to determine the therapeutic effects of renal sympathetic denervation (RSD) on cardiac dysfunction, fibrosis, and neurohumoral response in transverse aortic constriction (TAC) rats with chronic pressure overload. The present study demonstrated that RSD attenuated myocardial fibrosis and hypertrophy, and structural remodeling of the left atrium and ventricle, up-regulated cardiac beta adrenoceptor (beta-AR, including beta(1)AR and beta(2)AR) and sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) while down-regulated angiotensin II type 1 receptor (AT(1)R), and decreased plasma B-type natriuretic peptide (BNP), norepinephrine (NE), angiotensin II (Ang II), and arginine vasopressin (AVP) levels in TAC rats with chronic pressure overload. We conclude that RSD attenuates myocardial fibrosis, the left atrial enlargement, and the left ventricular wall hypertrophy; inhibits the overdrive of the sympathetic nervous system (SNS), renin-angiotensin-aldosterone system (RAAS), and AVP system in TAC rats with chronic pressure overload. RSD could be a promising non-pharmacological approach to control the progression of cardiac dysfunction.
This study demonstrated the potential of simultaneously recovering cellulosic solid residues (CSR) and producing cellulose nanocrystals (CNCs) by strong sulfuric acid hydrolysis to minimize cellulose ...loss to near zero. A set of slightly milder acid hydrolysis conditions than that considered as “optimal” were used to significantly minimize the degradation of cellulose into soluble sugars that cannot be economically recovered, but resulted in CSR that is easily recoverable through conventional centrifuge. It was found that the window for simultaneous recoveries of CSR and producing high yield CNC in strong acid hydrolysis was extremely narrow. However, we achieved significant CSR yield with near zero cellulose loss but without sacrificing CNC yield compared with that obtained at “optimal condition”. The resultant CSR contains sulfate ester groups that facilitated subsequent mechanical nano-fibrillation to cellulose nanofibrils (CNFs), a potential high value nanocellulosic material for a variety of applications.
In this paper, the torque production of fractional-slot concentrated-winding (FSCW) permanent-magnet synchronous machines (PMSMs) is analyzed from the perspective of the air-gap field harmonics ...modulation accounting for slotting effect. It is found that the average torque of FSCW PMSM is produced by both the principle of conventional PMSM and the magnetic gearing effect. A finite-element analysis (FEA) based equivalent current sheet model and harmonic restoration method is first used in FSCW PM machines with different slot-pole number combinations to quantify the respective contribution of the conventional PMSM and the magnetic gearing effect to the average torque. The influence of slot opening on the magnetic gearing effect, cogging torque, and torque ripple is analyzed. The results show that the magnetic gearing effect makes a nonignorable contribution to the average torque when a large slot opening stator is used. The expression of the gear ratio in FSCW PMSMs is derived. The influence of gear ratio on the contribution of the magnetic gearing effect to the total torque is investigated by FEA. The FEA-predicted torques are validated by experiments on the prototypes.
In the present work, pyrolysis kinetic mechanism was studied for regenerated cellulosic fiber (RCF) and composite RCF containing silicon/nitrogen flame retardants. Limited oxygen index and microscale ...combustion calorimeter tests show that the loading of nitrogen/silicon into the RCF enhanced flame retardancy. The kinetic triplets of the two kinds of samples were determined by applying iso-conversional methods and integral master plots approach. Compared to the untreated RCF, flame retardant (FR) treated RCF shows enhanced activation energy due to the physical barrier layer due to dehydration of silicate and charring effect resulting from organic–inorganic interaction. Exponential nucleation model can be successful in describing experimental results for RCF in higher conversion degree (0.4–0.9). Simultaneously, the degradation process of FR treated RCF in the main pyrolysis stage (0.2–0.7) is consistent with kinetics of nuclei growth and could be described by one-step reaction whose rate presented an Avrami–Erofeev-type model (
n
= 2.38).
The entorhinal cortex (EC) is one of the most vulnerable brain regions that is attacked during the early stage of Alzheimer's disease (AD). Here, we report that the synaptic terminals of pyramidal ...neurons in the EC layer II (ECII
) directly innervate CA1 parvalbumin (PV) neurons (CA1
) and are selectively degenerated in AD mice, which exhibit amyloid-β plaques similar to those observed in AD patients. A loss of ECII
-CA1
synapses disables the excitatory and inhibitory balance in the CA1 circuit and impairs spatial learning and memory. Optogenetic activation of ECII
using a theta burst paradigm rescues ECII
-CA1
synaptic defects and intercepts the decline in spatial learning and memory. These data reveal a novel mechanism of memory loss in AD mice via the selective degeneration of the ECII
-CA1
pathway.
Summary
Background
Tinea capitis is still common in developing countries, such as China. Its pathogen spectrum varies across regions and changes over time.
Objectives
This study aimed to clarify the ...current epidemiological characteristics and pathogen spectrum of tinea capitis in China.
Methods
A multicentre, prospective descriptive study involving 29 tertiary hospitals in China was conducted. From August 2019 to July 2020, 611 patients with tinea capitis were enrolled. Data concerning demography, risk factors and fungal tests were collected. When necessary, the pathogens were further identified by morphology or molecular sequencing in the central laboratory.
Results
Among all enrolled patients, 74·1% of the cases were in patients aged 2–8 years. The children with tinea capitis were mainly boys (56·2%) and were more likely than adults to have a history of animal contact (57·4% vs. 35·3%, P = 0·012) and zoophilic dermatophyte infection (73·5% vs. 47%). The adults were mainly female (83%) and were more likely than children to have anthropophilic agent infection (53% vs. 23·9%). The most common pathogen was zoophilic Microsporum canis (354, 65·2%), followed by anthropophilic Trichophyton violaceum (74, 13·6%). In contrast to the eastern, western and northeastern regions, where zoophilic M. canis predominated, anthropophilic T. violaceum predominated in central China (69%, P < 0·001), where the patients had the most tinea at other sites (20%) and dermatophytosis contact (26%) but the least animal contact (39%). Microsporum ferrugineum was the most common anthropophilic agent in the western area, especially in Xinjiang province.
Conclusions
Boys aged approximately 5 years were the most commonly affected group. Dermatologists are advised to pay more attention to the different transmission routes and pathogen spectra in different age groups from different regions.
What is already known about this topic?
Tinea capitis is an infection of the scalp and hair caused by dermatophytes and is still common in developing countries. Prepubertal children are mainly affected.
The pathogen spectrum of tinea capitis varies across different geographical areas and changes over time.
Nationwide prospective epidemiological surveys of tinea capitis in China are rare and out of date.
What does this study add?
This study provides data concerning the epidemiological characteristics and pathogen spectrum of tinea capitis in contemporary China.
Boys aged approximately 5 years were most commonly affected and were more likely than adults to have zoophilic dermatophyte infection.
The main pathogens of tinea capitis in China are zoophilic dermatophytes, mainly Microsporum canis. In contrast to the other regions, the predominant pathogens in central China are anthropophilic dermatophytes.
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