Sensitivity-Enhanced, Room-Temperature Detection of NH3 with Alkalized Ti3C2Tx MXene.

A layered Ti3C2Tx MXene structure was prepared by etching MAX-phase Ti3AlC2 with hydro-fluoric acid (HF), followed by alkalization in sodium hydroxide (NaOH) solutions of varying concentrations and for varying durations. Compared to sensors utilizing unalkalized Ti3C2Tx, those employing alkalized Ti3C2Tx MXene exhibited enhanced sensitivity for NH3 detection at room temperature and a relative humidity of 40%. Both the concentration of NaOH and duration of alkalization significantly influenced sensor performance. Among the tested conditions, Ti3C2Tx MXene alkalized with a 5 M NaOH solution for 12 h exhibited optimal performance, with high response values of 100.3% and a rapid response/recovery time of 73 s and 38 s, respectively. The improved sensitivity of NH3 detection can be attributed to the heightened NH3 adsorption capability of oxygen-rich terminals obtained through the alkalization treatment. This is consistent with the observed increase in the ratio of oxygen to fluorine atoms on the surface terminations of the alkalization-treated Ti3C2Tx. These findings suggest that the gas-sensing characteristics of Ti3C2Tx MXene can be finely tuned and optimized through a carefully tailored alkalization process, offering a viable approach to realizing high-performance Ti3C2Tx MXene gas sensors, particularly for NH3 sensing applications.

Progress in Gallium Oxide Field-Effect Transistors for High-Power and RF Applications.

Power electronics are becoming increasingly more important, as electrical energy constitutes 40% of the total primary energy usage in the USA and is expected to grow rapidly with the emergence of electric vehicles, renewable energy generation, and energy storage. New materials that are better suited for high-power applications are needed as the Si material limit is reached. Beta-phase gallium oxide (ß-Ga2O3) is a promising ultra-wide-bandgap (UWBG) semiconductor for high-power and RF electronics due to its bandgap of 4.9 eV, large theoretical breakdown electric field of 8 MV cm-1, and Baliga figure of merit of 3300, 3-10 times larger than that of SiC and GaN. Moreover, ß-Ga2O3 is the only WBG material that can be grown from melt, making large, high-quality, dopable substrates at low costs feasible. Significant efforts in the high-quality epitaxial growth of ß-Ga2O3 and ß-(AlxGa1-x)2O3 heterostructures has led to high-performance devices for high-power and RF applications. In this report, we provide a comprehensive summary of the progress in ß-Ga2O3 field-effect transistors (FETs) including a variety of transistor designs, channel materials, ohmic contact formations and improvements, gate dielectrics, and fabrication processes. Additionally, novel structures proposed through simulations and not yet realized in ß-Ga2O3 are presented. Main issues such as defect characterization methods and relevant material preparation, thermal studies and management, and the lack of p-type doping with investigated alternatives are also discussed. Finally, major strategies and outlooks for commercial use will be outlined.

Reconfigurable spin tunnel diodes by doping engineering VS2 monolayers.

We propose a reconfigurable spin tunnel diode based on a small spin-gapped semiconductor (non-doped VS2 monolayer) and semi-metallic magnets (doped VS2 monolayer) separated by a thin insulating tunneling barrier (h-BN). By using first-principles calculations assisted by the nonequilibrium Green's function method, we have carried out a comprehensive study of spin-dependent current and spin transport properties while varying the bias. The device exhibited a magnetization-controlled diode-like behavior with forward-allowed current under antiparallel magnetizations and reverse-forbidden current under parallel magnetizations at the two electrodes. The threshold voltage is tunable by the hole doping density of VS2 monolayers. The doping effect on VS2 monolayers indicates that the magnetic moments, the Heisenberg exchange parameters and Curie temperatures can be monotonically reduced by a larger hole doping density. Our study on VS2 heterostructures has presented a simple and practical device strategy with very promising applications in spintronics.

Species-Selective Detection of Volatile Organic Compounds by Ionic Liquid-Based Electrolyte Using Electrochemical Methods.

The detection of volatile organic compounds (VOCs) is an important topic for environmental safety and public health. However, the current commercial VOC detectors suffer from cross-sensitivity and low reproducibility. In this work, we present species-selective detection for VOCs using an electrochemical cell based on ionic liquid (IL) electrolytes with features of high selectivity and reliability. The voltammograms measured with the IL-based electrolyte absorbing different VOCs exhibited species-selective features that were extracted and classified by linear discriminant analysis (LDA). The detection system could identify as many as four types of VOCs, including methanol, ethanol, acetone, formaldehyde, and additional water. A mixture of methanol and formaldehyde was detected as well. The sample required for the VOCs classification system was 50 µL, or 1.164 mmol, on average. The response time for each VOC measurement is as fast as 24 s. The volume of VOCs such as formaldehyde in solution could also be quantified by LDA and electrochemical impedance spectroscopy techniques, respectively. The system showed a tunable detection range for 1.6 and 16% (w/v) CH2O solution by adjusting the composition of the electrolyte. The limit of detection was as low as 1 µL. For the 1.6% CH2O solution, the linearity calibration range was determined to be from 5.30 to 53.00 µmol with a limit of detection at 0.53 µmol. The mechanisms for VOCs determination and quantification are also thoroughly discussed. It is expected that this work could provide a new insight into the concept of electrochemical detection of VOCs with machine learning analysis and be applied to both VOCs gas monitoring and fluid detection.

Elevated exosome-transferrable lncRNA EPB41L4A-AS1 in CD56bright NK cells is responsible for the impaired NK function in neuroblastoma patients by suppressing cell glycolysis.

NK cells are one of key immune components in neuroblastoma (NB) surveillance and eradication. Glucose metabolism as a major source of fuel for NK activation is exquisitely regulated. Our data revealed a diminished NK activation and a disproportionally augmented CD56bright subset in NB. Further study showed that NK cells in NB presented with an arrested glycolysis accompanied by an elevated expression of the long noncoding RNA (lncRNA) EPB41L4A-AS1, a known crucial participant in glycolysis regulation, in the CD56bright NK subset. The inhibitory function of lncRNA EPB41L4A-AS1 was recapitulated. Interestingly, our study demonstrated that exosomal lncRNA EPB41L4A-AS1 was transferrable from CD56bright NK to CD56dim NK and was able to quench the glycolysis of target NK. Our data demonstrated that an arrested glycolysis in patient NK cells was associated with an elevated lncRNA in CD56bright NK subset and a cross-talk between heterogeneous NK subsets was achieved by transferring metabolic inhibitory lncRNA through exosomes.

Microfluidic on-chip valve and pump for applications in immunoassays.

On-chip valves can simplify a microfluidic chip and make it easy to operate. However, most on-chip valves already reported still need complicated manufacture and sophisticated supporting devices. In this work, we present a straightforward on-chip valve, which can be serially connected, to form an on-chip pump. The liquid can horizontally flow one way by the regular deformations of flexure strips in the two valves at both sides of the chamber under pressure changes in microchannels generated by repeated vertical movements of linear actuators. The volume of this system including the chip and the supporting device is 0.65 cubic decimeters, which is much smaller than that of reported systems with a volume of at least 12 cubic decimeters, and the weight of this system is only 0.56 kg, making it possible for point-of-care testing. We carry out an immunoassay of folic acid on chip, and the results show satisfactory reproducibility with acceptable coefficients of variation. We determine 163 clinical human serum samples for folic acid. Furthermore, we detect transferrin, cobalamin and folic acid simultaneously on one chip with both sandwich and competitive binding immunoassay methods. We anticipate that this on-chip valve and pump can be applied in immunoassays and other biosensing applications.

Methylmalonic acid levels in serum, exosomes, and urine and its association with cblC type methylmalonic acidemia-induced cognitive impairment.

Background: The cblC type methylmalonic acidemia is the most common methylmalonic acidemia (MMA) in China. The biochemical characteristics of this disease include elevated methylmalonic acid and homocysteine (HCY), increased propionylcarnitine (C3), decreased free carnitine (C0). In this study, we aimed to clarify the roles of these biomarkers in cblC-MMA induced cognitive impairment and evaluate the capacity of methylmalonic acid in different fluids or exosomes to distinguish cblC-MMA induced cognitive impairment. Methods: 15 non-inherited hyperhomocysteinemia (HHcy) patients, 42 cblC-MMA patients and 57 age- and sex-matched healthy children were recruited in this study. The levels of HCY were detected by an automatic immune analyzer. The levels of acylcarnitines and methylmalonic acid were detected by tandem mass spectrometer. Results: The main findings were all biomarkers as HCY, acylcarnitines and methylmalonic acid had capacities for distinguishing patients with cblC-MMA induced cognitive impairment from healthy children. The methylmalonic acid in different fluids or exosomes had good performances for distinguishing patients with cblC-MMA induced cognitive impairment from HHcy patients. The methylmalonic acid in serum exosomes and neuronal-derived exosomes were able to distinguishing cblC-MMA patients with cognitive impairment from patients without cognitive impairment. The methylmalonic acid in neuronal-derived exosomes might be helpful to evaluate the severity of cblC-MMA induced cognitive impairment. Discussion: Methylmalonic acid levels in serum exosomes, especially in serum neuronal-derived exosomes, serve as potential biomarkers for distinguishing cblC-MMA induced cognitive impairment.

Steep-slope transistors enabled with 2D quantum coupling stacks.

As down scaling of transistors continues, there is a growing interest in developing steep-slope transistors with reduced subthreshold slope (SS) below the Boltzmann limit. In this work, we successfully fabricated steep-slope MoS2transistors by incorporating a graphene layer, inserted in the gate stack. For our comprehensive study, we have applied density functional theory to simulate and calculate the change of SS effected by different 2D quantum materials, including graphene, germanene and 2D topological insulators, inserted within the gate dielectric. This theoretical study showed that graphene/MoS2devices had steep SS (27.2 mV/decade), validating our experimental approach (49.2 mV/decade). Furthermore, the simulations demonstrated very steep SS (8.6 mV/decade) in WTe2/MoS2devices. We conclude that appropriate combination of various 2D quantum materials for the gate-channel stacks, leads to steep SS and is an effective method to extend the scaling of transistors with exceptional performance.

Optimal Design for 3-PSS Flexible Parallel Micromanipulator Based on Kinematic and Dynamic Characteristics.

This paper proposes two optimal design schemes for improving the kinematic and dynamic performance of the 3-PSS flexible parallel micromanipulator according to different application requirements and conditions. Firstly, the workspace, dexterity, frequencies, and driving forces of the mechanism are successively analyzed. Then, a progressive optimization design is carried out, in which the scale parameters of this mechanism are firstly optimized to maximize the workspace, combining the constraints of the minimum global dexterity of the mechanism. Based on the optimized scale parameters, the minimum thickness and the cutting radius of the flexure spherical hinge are further optimized for minimizing the required driving forces, combined with constraints of the minimum first-order natural frequency of the mechanism and the maximum stress of the flexure spherical hinge during the movement of the mechanism. Afterward, a synchronous optimization design is proposed, in which the scale parameters are optimized to maximize the first-order natural frequency of the mechanism, combined with the constraints of a certain inscribed circle of the maximum cross-section of the workspace, the maximum stroke of the selected piezoelectric stages, and the maximum ultimate angular displacement of the flexure spherical hinge. The effectiveness of both optimization methods is verified by the comparison of the kinematic and dynamic characteristics of the original and optimized mechanism. The advantage of the progressive optimization method is that both the workspace and the driving forces are optimized and the minimum requirements for global dexterity and first-order natural frequency are ensured. The merit of the synchronous optimization method is that only the scale parameters of the mechanism need to be optimized without changing the structural parameters of the flexible spherical hinge.

Reference intervals of 14 biochemical markers for children and adolescence in China: the PRINCE study.

OBJECTIVES: The Pediatric Reference Intervals in China (PRINCE) was initiated to establish the reference intervals (RIs) of Chinese children, as well as to make it possible to compare the variability of biochemical markers among countries internationally. METHODS: Healthy participants, aged up to 20 years, from 11 provinces across China, were enrolled in PRINCE and according to a standard screening procedure, that included a questionnaire survey, physical examinations and laboratory tests. Fasting venous blood specimens were collected. All serum specimens were analyzed with Cobas C702 in the center laboratory, i.e. clinical laboratory of Beijing Children's Hospital, with certified qualification (ISO15189). The nonparametric method recommended by Clinical Laboratory Standards Institute guidelines, was used to calculate the age- and sex-specified RIs. RESULTS: Among the 15,150 participants enrolled, 12,352 children (6,093 males and 6,259 females) were included to calculate RIs. The RIs for total protein, albumin, globulin, calcium, phosphate, potassium, sodium, chlorine, alkaline phosphatase, γ-glutamyl transpeptadase, alanine aminotransferase, aspartate aminotransferase, creatinine and urea were established by age- or sex-partitions. Most biochemical markers displayed larger variability and higher dispersion during the periods between 28 days and 1 year old, and included 4-6 age partitions commonly during 1 to <20 years old. In addition, differences of RIs between sexes usually occurs around the initiation of puberty at 12-13 years old. CONCLUSIONS: The age- and sex-specified RIs of 14 biochemical markers in PRINCE study can provide a solid reference, which will be transferred into relevant RIs for other clinical laboratory's platforms according to the CLSI guidelines.

Analysis of Compliance and Kinetostatic of a Novel Class of n-4R Compliant Parallel Micro Pointing Mechanism.

A novel class of n-4R compliant parallel pointing mechanisms is proposed, and the compliance and kinetostatic model of the mechanism are established and analyzed successively. Firstly, the compliance model of a class of n-4R compliant parallel pointing mechanism is established based on the coordinate transformation. The model is verified by finite element analysis, and the influence of geometric parameter variations on the compliance performance of the mechanism is analyzed. Secondly, the mechanism is simplified to an equivalent spring system, and the governing equation of the equivalent spring system is constructed by utilizing the established compliance model. According to the governing equation, the mapping relationship between the input force and the output displacement of the mechanism is subsequently obtained, that is, the kinetostatic model. Then, the accuracy of the kinetostatic model is verified by two simulation examples: The spiral trajectory of the mobile platform center and the spatial pointing trajectory of the mechanism. The results of the two examples show that the deviations between the analytical results and the FE-results are within 0.038% and 0.857%, with the excellent consistency indicating the accuracy of the kinetostatic model. Finally, the influence of the geometric parameter values on the mapping matrix in the kinetostatic model is studied.

The transcription factor TOX is involved in the regulation of T-cell exhaustion in neuroblastoma.

T-cell exhaustion is one of the key reasons for attenuated T-cell cytotoxicity against tumours. At both the expression and epigenetic levels, a number of genes, including the transcription factor TOX, are believed to be implicated in regulating T-cell exhaustion. In the present study, we found that in NB patients, the ratio of exhausted T cells, featuring upregulated PD-1 and Tim-3, was increased. Meanwhile, the expression of inhibitory surface receptors, including Lag-3, CD160, VISTA and KLRG1, was also increased, but this was accompanied by a reduced ability to release the effector molecules IL-2, IFN-γ, TNF-α and Granzyme B in CD3+ T cells from NB patients. It is noteworthy that NB-derived memory T cells (Tm) showed more obvious exhausted characteristics than other T cells. Moreover, the T cells from NB patients possessed a higher potential for exhaustion conversion upon in vitro TCR stimulation in our time-course culture experiment. In NB patients, T-cell exhaustion was demonstrated to correlate with the elevated expression of TOX in freshly sorted CD3+ T cells as well as in anti-CD3 stimulated PBMCs. Most importantly, our data supported the idea that the hypomethylation of the TOX promoter may be one of the initiators that regulates TOX expression and enables TOX to play a crucial role in T-cell exhaustion reprogramming in NB patients.

Age and sex specific reference intervals of 13 hematological analytes in Chinese children and adolescents aged from 28 days up to 20 years: the PRINCE study.

OBJECTIVES: Pediatric Reference Intervals in China (PRINCE) is a nationwide initiative that aims to establish and validate harmonized reference intervals (RIs) for Chinese children and adolescents, in which 15,150 healthy volunteers aged up to 20 years were recruited from 11 centers to establish RIs and 7,557 children and adolescents were enrolled from 21 centers to validate RIs. METHODS: The complete blood cell counts (CBC) of venous whole blood were measured by hematology analyzers through Sysmex systems in different centers. Age- and sex-specific RIs were calculated according to the guidelines. RESULTS: Unlike adults with certain levels of analyte concentrations, hematological parameters of children changed through growth and development. Red blood cell counts, hemoglobin, and hematocrit increased with age, and revealed higher concentrations in boys than girls after puberty. White blood cell counts and platelet counts showed significant higher levels than adults before 2 years of age, and then gradually decreased without distinct sex differences. In addition, lymphocyte counts decreased with age while neutrophil counts showed an opposite trend. The lower and upper limits of pediatric RIs of CBC were different from those of adults. CONCLUSIONS: The validation of RIs indicated that the PRINCE study provided a version of RIs suitable for most of regions in China. This first harmonized pediatric RIs of CBC across China provided a robust database to understand the dynamic changes of hematologic parameters from birth to adolescence, and will contribute to clinical diagnosis and prognosis evaluation for pediatric patients as well.

Continuous reference intervals for 21 biochemical and hematological analytes in healthy Chinese children and adolescents: The PRINCE study.

OBJECTIVES: Critical gaps have existed in pediatric reference intervals in China. In this study, we presented the sex and age distributions of 21 laboratory analytes from childhood to adolescence, and established the corresponding continuous reference intervals based on direct samples. METHODS: We used the data from the Pediatric Reference Intervals in China (PRINCE), which is a nation-wide cross-sectional study enrolling 15,150 healthy children and adolescents aged 0 - <20 years from 11 centers across China. Blood samples were collected and analyzed by trained staff following standard operating procedures. Biochemical tests were performed with Cobas C702 at the central laboratory, and hematological tests were performed with Sysmex XE, XN, or XS that satisfy the national standards at each participating center. Children younger than 3 months were excluded due to high neonatal variability and insufficient samples. Continuous reference intervals were calculated using the generalized additive models for location, shape, and scale, and were validated among another 387 healthy volunteers. RESULTS: We provided pediatric continuous reference intervals for 21 commonly used biochemical and hematological analytes in China, and depicted the changes in analyte concentrations from 3 months to 20 years. The out-of-range values for all analytes were less than 10%, indicating a well applicability of the continuous reference intervals to the general pediatric population. CONCLUSIONS: This is the first comprehensive report of continuous reference intervals based on healthy Chinese children, reflecting the complex dynamic trends of analytes from infancy to adulthood. Applying continuous reference intervals to clinical practice would not only improve the laboratory test result interpretation, but also help better clinical decision making.

Recent Progress in Smart Electronic Nose Technologies Enabled with Machine Learning Methods.

Machine learning methods enable the electronic nose (E-Nose) for precise odor identification with both qualitative and quantitative analysis. Advanced machine learning methods are crucial for the E-Nose to gain high performance and strengthen its capability in many applications, including robotics, food engineering, environment monitoring, and medical diagnosis. Recently, many machine learning techniques have been studied, developed, and integrated into feature extraction, modeling, and gas sensor drift compensation. The purpose of feature extraction is to keep robust pattern information in raw signals while removing redundancy and noise. With the extracted feature, a proper modeling method can effectively use the information for prediction. In addition, drift compensation is adopted to relieve the model accuracy degradation due to the gas sensor drifting. These recent advances have significantly promoted the prediction accuracy and stability of the E-Nose. This review is engaged to provide a summary of recent progress in advanced machine learning methods in E-Nose technologies and give an insight into new research directions in feature extraction, modeling, and sensor drift compensation.

Determination of Cytokines and Oxidative Stress Biomarkers in Cognitive Impairment Induced by Methylmalonic Acidemia.

OBJECTIVE: Methylmalonic acidemia (MMA) is the most common organic acidemia in children. Many patients with MMA suffered from cognitive impairments. The aim of this study was to identify the significance of cytokines and oxidative stress biomarkers in MMA-induced cognitive impairment. METHODS: We enrolled 64 children with combined MMA and homocystinuria and 64 age- and sex-matched healthy volunteers. Participants were subsequently classified as with or without cognitive impairments using a uniform neuropsychological assessment test. Serum samples were collected. The serum levels of cytokines and oxidative stress biomarkers were measured using the ELISA or chemical methods. RESULTS: Compared to control group, the serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, malondialdehyde (MDA), and nitric oxide (NO) in the MMA patients increased markedly (p < 0.05); glutathione (GSH) and superoxide dismutase (SOD) decreased obviously (p < 0.01). The levels of IL-6, TNF-α, NO, and MDA in the serum were negatively associated with DQ or IQ scores. The levels of GSH and SOD in the serum were positively correlated with DQ or IQ scores. After receiver operating characteristic curve analysis, NO was the most useful individual marker for distinguishing the cognitive dysfunction, corresponding to the area under ROC curve (AUC) of 0.82 (95% CI, 0.74-0.91), sensitivity of 76.60%, and specificity of 80.25%. GSH and MDA were also useful for diagnosis of MMA-induced cognitive dysfunction, corresponding to the AUC of 0.80 (95% CI, 0.70-0.89), and 0.73 (95% CI, 0.63-0.82), respectively. The sensitivity and specificity of GSH were 72.34 and 80.25%, respectively. The sensitivity and specificity of MDA were 85.11 and 51.85%, respectively. CONCLUSIONS: The high-concentration methylmalonic acid in the blood induced immune cells to release pro-inflammatory cytokines such as TNF-α and IL-6. These cytokines and high-concentration methylmalonic acid stimulated the immune cells to produce reactive oxygen species (ROS) and reactive nitrogen species (RNS). The serum methylmalonic acid, cytokines, ROS, and RNS were across the blood-brain barrier and induced cognitive impairment. The small molecule substances such as serum NO, MDA, and GSH participated in the process of neuroinflammation and oxidative stress injury induced by MMA and could be useful for distinguishing the cognitive impairment.

Photonic arbitrary waveform generation based on the temporal Talbot effect.

In this paper, we propose a novel photonic approach for generating arbitrary waveform. The approach is based on the property of real-time Fourier transform in the temporal Talbot effect, where the spectrum of the modulating analog signal is converted into the output time-domain waveform in each period. We present a concise and strict theoretical framework to reveal the relationship of real-time Fourier transform between the optical signals before and after the dispersion. A proof-of-concept experiment is implemented to validate the presented theoretical model. We propose to generate symmetrical or asymmetrical arbitrary waveforms by using double-sideband or single-sideband modulation, respectively, which is verified by simulation results. It is shown that the given approach can be used to generate a repetition-rate multiplied optical pulse train with arbitrary waveform by simply using a multi-tone RF signal with appropriate frequencies and powers.

Families of asymmetrically functionalized germanene films as promising quantum spin Hall insulators.

Topological insulators (TIs), exhibiting the quantum spin Hall (QSH) effect, are promising for developing dissipationless transport devices that can be realized under a wide range of temperatures. The search for new two-dimensional (2D) TIs is essential for TIs to be utilized at room-temperature, with applications in optoelectronics, spintronics, and magnetic sensors. In this work, we used first-principles calculations to investigate the geometric, electronic, and topological properties of GeX and GeMX (M = C, N, P, As; X = H, F, Cl, Br, I, O, S, Se, Te). In 26 of these materials, the QSH effect is demonstrated by a spin-orbit coupling (SOC) induced large band gap and a band inversion at the Γ point, similar to the case of an HgTe quantum well. In addition, engineering the intra-layer strain of certain GeMX species can transform them from a regular insulator into a 2D TI. This work demonstrates that asymmetrical chemical functionalization is a promising method to induce the QSH effect in 2D hexagonal materials, paving the way for practical application of TIs in electronics.

Comparison of four algorithms on establishing continuous reference intervals for pediatric analytes with age-dependent trend.

BACKGROUND: Continuous reference intervals (RIs) allow for more precise consideration of the dynamic changes of physiological development, which can provide new strategies for the presentation of laboratory test results. Our study aimed to establish continuous RIs using four different simulation methods so that the applicability of different methods could be further understood. METHODS: The data of alkaline phosphatase (ALP) and serum creatinine (Cr) were obtained from the Pediatric Reference Interval in China study (PRINCE), in which healthy children aged 0-19 years were recruited. The improved non-parametric method, the radial smoothing method, the General Additive Model for Location Scale and Shape (GAMLSS), and Lambda-Median-Sigma (LMS) were used to develop continuous RIs. The accuracy and goodness of fit of the continuous RIs were evaluated based on the out of range (OOR) and Akaike Information Criterion (AIC) results. RESULTS: Samples from 11,517 and 11,544 participants were used to estimate the continuous RIs of ALP and Cr, respectively. Time frames were partitioned to fulfill the following two criteria: sample size = 120 in each subgroup and mean difference = 2 between adjacent time frames. Cubic spline or penalized spline was used for curve smoothing. The RIs estimated by the four methods approximately overlapped. However, more obvious edge effects were shown in the curves fit by the non-parametric methods than the semi-parametric method, which may be attributed to insufficient sample size. The OOR values of all four methods were smaller than 10%. CONCLUSIONS: All four methods could be used to establish continuous RIs. GAMLSS and LMS are more reliable than the other two methods for dealing with edge effects.