Current health resources required for the management of ankylosing spondylitis in developing areas of China

To the Editor:Ankylosing spondylitis(AS)is a chronic inflammatory disease that causes bony fusion of spine and sacroiliac joints,resulting in restricted spinal movement and deformity.In China,the prevalence of AS is about 0.29%with a male to female ratio of approximately 3:1,and most cases occur in the adolescent period.[1]The misdiagnosis rate of AS patients in China is>50%.

Understanding the Percolation Effect in Triboelectric Nanogenerator with Conductive Intermediate Layer

Introducing the conductive intermediate layer into a triboelectric nanogenerator(TENG)has been proved as an efficient way to enhance the surface charge density that is attributed to the enhancement of the dielectric permittivity.However,far too little attention has been paid to the companion percolation,another key element to affect the output.Here,the TENG with MXeneembedded polyvinylidene fluoride(PVDF)composite film is fabricated,and the dependence of the output capability on the MXene loading is investigated experimentally and theoretically.Specifically,the surface charge density mainly depends on the dielectric permittivity at lower MXene loadings,and in contrast,the percolation becomes the degrading factor with the further increase of the conductive loadings.At the balance between the dielectric and percolation properties,the surface charge density of the MXene-modified TENG obtained 350%enhancement compared to that with the pure PVDF.This work shed new light on understanding the dielectric and percolation effect in TENG,which renders a universal strategy for the high-performance triboelectronics.

Improvement of delayed diagnosis of ankylosing spondylitis in a Chinese population

To the Editor:Delayed diagnosis is a challenge in ankylosing spondylitis(AS),a representative phenotype of axial spondylarthritis(ax-SpA).Such delay might be improving,^([1])as there have been several updates on the diagnosis criteria of AS and ax-SpA,especially the 2009 Assessment of SpondyloArthritis International Society(ASAS),^([2])which recognized MRI as a powerful approach to detect early-stage lesions.However,there is still limited knowledge of whether the diagnostic delay has been improved in China.Therefore,we performed a comparative study of two datasets from the same hospital collected over 14 years.

Blood pressure monitoring via double sandwich-structured triboelectric sensors and deep learning models

Real-time blood pressure monitoring is essential for the timely diagnosis and treatment of cardiovascular disease.Many traditional prediction methods estimate blood pressure by measuring multiple sets of physiological signals with energyconsuming sensors.Herein,a continuous,cuffless and self-powered blood pressure monitoring system was developed based on a new double sandwich-structured triboelectric sensor and a novel blood pressure method estimation.A pyramid-patterned sensor based on the double sandwich structure realizes a sensitivity of 0.89 V/kPa in a linear range of 0–35 kPa,which is more than twice of the conventional single electrode structure.The sensor processes a low pressure detection limit of 1 g andfast response time of 32 ms.Hence,it can easily capture the pulse signal at the radial artery.Furthermore,a novel method for estimating blood pressure using pulse waves accompanied by the user’s background information was proposed.This method measures only one set of pulse signals and is portable.A deep learning model with multi-network structures was developed to improve the estimation accuracy.The mean absolute error and standard deviation of error for systolic and diastolic blood pressure(SBP and DBP)estimations were 3.79±5.27 and 3.86±5.18 mmHg,respectively.This work reveals a new sensing structure of triboelectric sensors and offers a novel method for blood pressure estimation.