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Disc brake performance is an important guarantee for the safe operation of high-speed trains. Brake pad fastener snap rings may fail during train braking, causing the friction body to fall off, which is a serious threat to the safety of train operation. This article establishes a finite element model of brake pads/discs taking into account the thermal-mechanical coupling field in the braking process. The temperature distribution of the brake disc surface, the displacement and stress results of the snap rings at different positions are investigated. The results show that the temperature of the brake disc rises and then falls during braking, and the surface temperature of the brake disc is spread in the form of an annular band. The highest displacement and stress variations are found in the snap ring group around the speed entrance area and the inner side of the brake pad. In the x and z directions, the average displacement changes are 0.1967 and 0.1233 mm, respectively. The average changes in contact stress and internal stress are 9.8 and 15.5 MPa. The results of the service behaviour of the snap ring provide a basis for the study of snap ring failure.

The curvature variation regularity of the blade surface is complex and requires a high level of machining accuracy. In order to research the influence of interpolation tolerance on the machining accuracy of blade surface at different positions, the non-uniform rational b-spline was used to build the blade surface and analyze the curvature variation regularity at different positions, and the distribution regularity of interpolation tolerance at different curvature positions on interpolation moving points was explored based on the NC (Numerical Control) program. In addition, the NC interpolation principle is used to analyze the effect of different interpolation tolerance parameters on the machining accuracy of blade surfaces, and the appropriate interpolation moving point coordinates were obtained through the five-axis coordinate system transformation theory, and the five-axis cutting simulation and experiment were carried out. The results show that there are many interpolation moving points at the position with large curvature. With interpolation tolerances of 0.1 mm, 0.03 mm and 0.003 mm, the interpolation errors obtained in the regions with large curvature are 0.005 mm, 0.0034 mm and 0.0025 mm, respectively. The smaller the interpolation tolerance, the smaller the interpolation error. What is more, the smaller the interpolation tolerance is, the more obvious the improvement of interpolation accuracy will be when the interpolation tolerance is reduced. Besides, when sampling length of 250 μm, the surface roughness (Ra) detected at the small curvature position and the large curvature position are 0.434 and 1.070μm respectively. The surface roughness is better in position with smaller curvature, however, it is worse in position with larger curvature. The analytical regularity is in good agreement with both simulation and experiment values. It provides a reference for improving NC machining accuracy for similar blade surfaces.

Due to the limited availability of fault samples and the expensive nature of marking fault samples in Electric Multiple Unit (EMU) gearbox monitoring data, a study was conducted to simulate the degradation process of key components in the CRH5 gearbox using rigid–flexible coupling dynamics. Vibration acceleration data from the simulation were utilized to create a six-dimensional hybrid feature domain representing the degradation process. By leveraging the capabilities of the Hidden Markov Model (HMM) for handling hidden transitive probabilities in temporal data and Gated Recurrent Unit (GRU) for addressing long-distance and high-dependence temporal data, a GRU-HMM fault prediction model was developed. This model was validated using monitoring data and the six-dimensional hybrid feature domain from the CRH5 gearbox and compared against actual maintenance records. The findings indicated that the GRU-HMM fault prediction model can effectively recognize the degradation patterns of multiple components, offering higher accuracy in fault prediction compared to traditional models. These research outcomes are expected to optimize EMU maintenance schedules based on usage conditions, enhance EMU utilization rates, and reduce operational and maintenance costs, thereby providing valuable theoretical support.

The milling force of hollow thin-walled welded structural parts varies greatly at each position, and the analytical model was less studied, which affects the prediction accuracy of milling force. In order to construct an analytical model of the milling force, a model was constructed to calculate the cutting depth of the tool slot milling based on the contact relationship between the cutter and the workpiece. Moreover, based on the structural properties of the hollow thin-walled welded structural parts, the effective cutting depth function at different locations was derived by using infinitesimal element integration method, and the dynamic milling force prediction model was solved at each location. Furthermore, the differences between the theoretical and experimental values were compared and analyzed from the viewpoint of the peak value and the trend of the milling force, and the chip thickness was verified. The results show that the milling force is minimal in all directions at the position of the upper and lower skin zone, and maximal at the position of the inclined rib zone. What’s more, due to the large cutting depth at the position of the vertical plate zone, the milling force in X direction increases first and then decreases, and continue increases at the position of the vertical plate zone, besides, the milling force in Y and Z directions increases first and then decreases. What’s more, the prediction errors of the forces in X, Y and Z directions at the position of the upper and lower skin plate zone are 7.01%, 2.04% and 8.24%, respectively, the prediction errors of the forces in X, Y and Z directions at the position of the inclined rib plate zone are 3.22%、8.76% and 7.77%, respectively, and the prediction errors of the forces in X, Y and Z directions at the position of the vertical plate zone are 7.01%, 2.04% and 8.24%, respectively.

The deformation characteristics of GaSb are investigated by employing nano-scratch tests to understand the material removal mechanism during ultra-precision grinding. The nano-scratches are obtained by a cube-corner tip under the two linear normal load conditions (0–30 mN and 0–60 mN). The normal force/scratch distance-penetration depth curves and the characteristics of chips and cracks are analyzed to understand the transition mechanism of ductile to brittle removal. In addition, the maximum principal stress near the bottom of the scratch is calculated to analyze the deformation behavior. The results revealed that the deformation behavior of three zones of deformation is plastic deformation, the transition from plastic to brittle deformation, and brittle deformation, respectively. The change rate of stress is significant differences in the zone of brittle-ductile transition. The critical ratio between mean contact pressures and hardness in the transition region is determined as 0.39 and 0.21, respectively.

This paper examines the effects of thermo-solid coupling and the influence of braking parameter changes on the vibration characteristics of high-speed train disc brakes. A multi-flexible body dynamics model of high-speed train disc brakes considering thermo-solid coupling was established to study the vibration characteristics of high-speed train disc brakes during service. The results show that the uneven distribution of temperature and stress produced during the brake disc’s service was the primary cause of the warping deformation of the brake disc, which prevented the brake disc and the brake pads from making sufficient contact and caused vibration while braking. By comparing the analytical findings of whether the model was subject to the coupling effect or not, the influence of thermo-solid coupling on the braking procedure was demonstrated from the standpoint of energy distribution. The severity of the high-speed train brake disc vibration gradually increased along with the braking pressure and initial speed. In addition, vibration aggravated the instability of the braking process, which could lead to thermoelastic instability and is harmful to the braking performance of the brake. These findings provide theoretical support for designing and manufacturing disc brakes for high-speed trains.

The phenomenon of coal cake collapse is often caused by the unstable operation of the elastic cam in a large coal cake tamper. Aiming at this problem, the mechanical characteristics of the composite rubber elements during cam rotation are studied. A rubber piecewise-function constitutive model is established based on phenomenological theory, and different rubber constitutive model coefficients are obtained according to rubber test data. A contact simulation model between the elastic cam and the tamping hammer friction plate is established to obtain the stress–strain law of the composite rubber elements and the pressure-displacement curve of the elastic cam. The stiffness test platform of the elastic cam is designed, and the differences in results between the test and the simulation are discussed. The results show that the stress–strain curve of rubber has a nonlinear increasing trend and the error between the proposed piecewise function and the test value is less than 2%. As the cam displacement increases from 1 mm to 10 mm, the cam pressure increases from 7715 N to 40,000 N. The simulation results of the rubber stress–strain relationship using the piecewise-function constitutive model are closer to the test data than the simulation results using the elastic modulus as a constant, and the error is less than 6.18%.

A tamping machine is the key equipment of large coking coal cake forming in the steelmaking industry, where the loose coal is compacted into a coal cake by the reciprocating movement of its tamping hammer. In the long-term friction process, the third particle attached to the surface of the friction pair of the hammer lifting mechanism often causes the tamping hammer to slip and wear the tamping hammer friction plate, resulting in an insufficient height of the hammer, uneven work of the tamping hammer, coal cake collapse and other problems. In order to avoid the adverse effect of the third body on the surface of the friction pair, this paper studies the formation of the third body on the friction surface of the lifting hammer mechanism of the coal cake tamper. The cam material (Q345B) of the hammer lifting mechanism and the copper-based powder-metallurgy composite material of the friction plate of the tamping hammer are prepared into the pin-disk friction test disk and pin, respectively. Based on the characteristics of the friction temperature variation in the pin-disk test, an equivalent accumulation method is proposed, that is, the wear state of several samples at different wear times is equivalent to characterize the wear condition of a sample at different stages during continuous wear, and the different stages of the third body formation process are obtained. By analyzing the change of the composition of the third body and the content proportion of each element on the surface of the bottom plate at different wear times, it is determined that Cu is the key index of the third body. The content of the Cu element is used to characterize the content of the third body on the surface of the disk sample, and the formation rule of the third body on the surface of the disk is inferred. Through an image processing method of color analysis, the distribution law of the third body on the whole disk is identified. The properties of the third-body material on the disk surface are obtained by analyzing the changes of hardness and morphology at each friction stage. The results show that with the increase of friction time, the content of Cu on the disk surface increases to 22% and then decreases to 15%. The microhardness of the friction surface reaches its highest at 7 min, which is 1.4 times that of the Q345B material. The maximum disk surface roughness is 0.452 µm. Finally, the formation process of the third body is summarized in three stages: formation, equilibrium and damage. Therefore, the frictional properties of the surface of the friction pair vary from weak to strong to weak with the formation characteristics of the third body.

For the friction and wear of the braking surface of the disc brake, the mechanism of friction contact deformation of rough surface is analyzed. Considering elastoplastic contact mechanics of the friction surfaces, combined with Archard wear calculation theory, a wear calculation model of fractal rough surface is established, and a wear life prediction of the brake disc is proposed. Based on high-speed and heavy-load braking conditions, the influence of different braking parameters on the surface wear of brake disc is studied. Moreover, a pin-on-disc wear test is used to verify the validity of the wear calculation model, and the average relative error of test and simulation is 4.97%. The research results show that the fractal parameters affect the complexity of the rough surface, and surface wear is mainly caused by interface plastic contact. The friction coefficient is large, which can strengthen the surface shear effect. Large load and high speed would increase the real contact area of the surface and increase the wear volume per unit time. Furthermore, the wear life of the brake disc could be estimated, which is of great significance for raising the wear life of the brake disc, improving braking life and braking efficiency.

The brake disc plays a crucial role to keep the stable braking of a high-speed and heavy-duty disc brake. There is always high temperature, brake vibration, and even serious deformation under braking pressure and frictional resistance. To improve brake performance, this paper aims to find new internal and surface structures of the brake disc. An equivalent moving load (EML) topology optimization method for internal structure is proposed. Topography optimization method oriented to displacement and stress control for surface structure is carried out. Multiobjective functions containing thermal-structural coupled rigidity and natural frequency of the brake disc are established in the internal and surface structure optimizations. Internal and surface structures of the brake disc are optimized, and the mechanic properties of the brake disc are improved. Thermal-structural coupling and modal analyses are verified with high-speed and heavy-duty brake working conditions. The results show that new brake disc structures meet the requirements, and the effectiveness of the proposed EML topology optimization and topography optimization methods has been proved.

For the unique structural characteristics of ventilated brake discs and the complex problem of energy conversion during braking, a calculation method for energy conversion of the ventilated brake disc based on simultaneous heat generation and heat dissipation is proposed. The transient heat transfer model of the ventilated brake disc for high-speed trains is established. Considering the control equations of heat generation–heat dissipation and plate–cylinder convection heat transfer, the virtual simulation of the energy change of the ventilated brake disc during the braking process is carried out. The temperature and stress distribution of contact friction surface and clearance structure of the ventilated brake disc are analysed from the perspective of function conversion. The results show that the heat generated by the ventilated brake disc increases nonlinearly, and the heat dissipated increases linearly. The heat of ventilated brake disc increases with the increase of braking time, but its growth rate decreases continuously. The maximum temperature of the ventilated brake disc is 268 °C, which appears on the friction surface. After braking, its heat is 6.636 × 106 J. The analysis results and methods provide a basis for optimizing the structure of ventilated brake discs.

Titanium alloys are widely used in aerospace, the military industry, electronics, automotive fields, etc., due to their excellent properties such as low density, high strength, high-temperature resistance, and corrosion resistance. Many components need to be finished precisely after being cut in these applications. In order to achieve high-quality and high-efficiency finishing of titanium alloys, ultrasonic-assisted magnetic abrasive finishing (UAMAF) was introduced in this research. The machining performance for UAMAF of a titanium alloy was studied by experimentally comparing UAMAF and magnetic abrasive finishing (MAF). The results show that the cutting force of UAMAF can reach 2 to 4 times that of MAF, and it decreases rapidly with the increase in the machining gap due to the energy loss of ultrasonic impact in the transmission between magnetic abrasives. The surface roughness of UAMAF can reach about Ra 0.075 μm, which is reduced by about 59% compared with MAF. The main wear type of the magnetic abrasive is that the diamond grits fell off the magnetic abrasive in both UAMAF and MAF. The uniform wear of the magnetic abrasive is realized, and the utilization ratio of the magnetic abrasive is obviously improved in UAMAF.

For material fracture and severe wear in braking conditions, the discrete element method (DEM) is used to simulate the wear process of the braking interface explicitly. Based on the central difference method, particle motion equations are established considering the influence of elemental damping on particle contact. Combined with the Particle Flow Code (PFC) software, a DEM wear model of the braking interface is established using the parallel bond modeling method. The braking wear process is simulated, and the material damage process is investigated. The simulation results demonstrate that with the increase of the initial braking load and the initial braking speed, the wear depth increased by 24.75% and 16.22%, respectively. The increase in the number of detached particles leads to an increasing trend of fracture force chains, which increases the thickness of the flowing particle layer, revealing the micro-wear mechanism of the braking interface.

Due to the complexity of electrical discharge machining (EDM), there is no perfect theory to explain the mechanisms of material erosion, ejection and solidification during the machining process. Therefore, this paper analyzed the micro-process of a single-pulse discharge during EDM and studied the thermal erosion, ejection and solidification processes of the electrode materials. A thermal-fluid simulation model that considered melting-solidification was established. A mathematical model of vapor flow considering the impact pressure was developed, and it was compiled and loaded as a material ejection force in simulations with a user defined function (UDF). The changes in the material ejection, crater formation and material solidification processes at different discharge times were studied. Finally, the simulation results were verified by single-pulse material discharge experiments, which provided a reference for additional understanding of the micro material discharge processes during EDM.

The technology of magnetic abrasive finishing is one of the important finishing technologies. Combining with low-frequency vibration and ultrasonic vibration, it can attain higher precision, quality and efficiency. The characteristics and the related current research of magnetic abrasive finishing, vibration assisted magnetic abrasive finishing and ultrasonic assisted magnetic abrasive finishing are introduced. According to the characteristics of the difficult-to-machine alloy's complex surface, the important problems for further study are presented to realize the finishing of complex surface with the technology of magnetic abrasive finishing, such as increasing the machining efficiency by enhancing the magnetic flux density of machining gap and compounding of magnetic energy and others, establishing of the control function during machining and the process planning method for magnetic abrasive finishing of complex surface under the space geometry restraint of complex surface on magnetic pole, etc.

With the development of (electrical discharge machining) EDM technology, composite tools with special features gradually replace the traditional single-material tools and have become widely used in specific processing conditions. In order to predict the wear of composite tool effectively, in this paper, a material removal model of single-pulse EDM with composite tools was established by using the finite element method. The surface temperature distribution of the composite tool was obtained by taking the copper-die steel tool as the analysis object. And the shape of discharge crater as well as the removal volume was obtained by the element birth and death method. The influences of discharge parameters and tool materials on the removal volume were analyzed respectively. The EDM experiments were carried out by using copper-die steel as the composite tool to verify the simulation results. It shows that the errors between actual machining results and the simulation results are less than 10%, which proves the accuracy of the simulation model.

Aiming at the problem of obvious tool length wear and side wear in the small hole processing of EDM, the nickel-coated composite electrode and diamond-nickel-coated composite electrode were prepared by chemical composite coating using brass, copper, molybdenum, and copper-tungsten alloy materials as the matrix material. Comparative experiments of EDM small hole machining using composite tools were carried out on die steel. The effects of nickel-coated composite electrode and diamond-nickel-coated composite electrode on tool length wear, tool side wear, and tool shape change were analyzed. The results show that the diamond-nickel-coated composite electrode can effectively reduce both the length wear and side wear of the electrodes.

In view of the braking process for the megawatt wind turbine brakes, considering the geometric and motion characteristics of brake pads and brake discs, a displacement gradient circulation method is put forward in this article, to resolve the deviation of coupling results caused by the difference of friction effect along the radial/circumferential direction of brake disc, and the thermal–structural coupling analysis of friction pair during the braking process is carried out. A three-dimensional model of transient heat transfer for brake friction pair is built based on the Abaqus software. The heat flow density is loaded by the displacement gradient circulation method, which is used to calculate the frictional heat flow during the braking process. The analysis results show that along the circumferential direction of the brake disc the temperature distribution in the friction zone is non-uniform and the temperature starting from the contact position of the brake disc and the brake pad decreases along the counterclockwise direction. The thermal stress caused by the temperature field during the braking process is the main factor causing the brake disc/pad failure. The effectiveness of the method and the model is verified by the designed inertia braking experiments. The analytical method proposed in this article provides a reference for simulating the friction braking process of large-size disc brakes.

In electrical discharge machining (EDM) process, the debris removed from electrode material strongly affects the machining efficiency and accuracy, especially for the deep small hole machining process. In case of Ti alloy, the debris movement and removal process in gap flow between electrodes for small hole EDM process is studied in this paper. Based on the solid-liquid two-phase flow equation, the mathematical model on the gap flow field with flushing and self-adaptive disturbation is developed. In our 3D simulation process, the count of debris increases with number of EDM discharge cycles, and the disturbation generated by the movement of self-adaptive tool in the gap flow is considered. The methods of smoothing and remeshing are also applied in the modeling process to enable a movable tool. Under different depth, flushing velocity, and tool diameter, the distribution of velocity field, pressure field of gap flow, and debris movement are analyzed. The statistical study of debris distribution under different machining conditions is also carried out. Finally, a series of experiments are conducted on a self-made machine to verify the 3D simulation model. The experiment results show the burn mark at hole bottom and the tapered wall, which corresponds well with the simulating conclusion.

When machining a small hole with high aspect ratio in EDM, it is hard for the flushing liquid entering the bottom gap and the debris could hardly be removed, which results in the accumulation of debris and affects the machining efficiency and machining accuracy. The assisted ultrasonic vibration can improve the removal of debris in the gap. Based on dynamics simulation software, Fluent, a three-dimensional (3D) model of debris movement in the gap flow field of EDM small hole machining assisted with side flushing and ultrasonic vibration is established in this paper. The laws of different amplitudes and frequencies and different aspect ratios on debris distribution and movement are quantitatively analyzed. The motion height of debris was observed under different conditions. The research results show that periodic ultrasonic vibration can promote the movement of debris, which is beneficial to the removal of debris in the machining gap. When compared to traditional small hole machining in EDM, the debris in the machining gap were greatly reduced, which ensures the stability of the machining process and improves the machining efficiency.

In view of the development trend of rail vehicles towards higher operating speed and low power consumption, a scheme for a lightweight rail vehicle body is proposed, based on sensitivity analysis. Using topology optimization of the vehicle body section structure, finite element models of the vehicle body section structure under single working conditions and multiple working conditions were established, respectively, and the force transmission path of the vehicle body structure under different working conditions was obtained under different working conditions. The topology of the cross-sectional structure of the vehicle body was optimized by the compromise planning method with weights. Then, a reconstruction and performance analysis of the car body section was carried out based on the optimization results and finally the finite difference method was used to analyze the sensitivity of the vehicle body structure and the vehicle body size was optimized based on the sensitivity analysis results. The results showed that the weight reduction rate of the railway vehicle body section stiffened plate was 4.47% compared to the optimization period and the modal performance analysis results of the optimized structure met the requirements. The weight reduction ratio of the optimized body structure was 21.6%. [ABSTRACT FROM AUTHOR]

Abstract Electrochemical modification of animal skin is a new material preparation method and new direction of research exploration. In this study, under the action of the electric field using NaCl as the supporting electrolyte, the effect of electrolysis on Glycyl-glycine(GlyGl), gelatin(Gel) and Three-dimensional rawhide collagen(3DC) were determined. The amino group of GlyGl is quickly eliminated within the anode region by electrolysis isolated by an anion exchange membrane. Using the same method, it was found that the molecular weight of Gel and the isoelectric point of the Gel decreased, and the viscosity and transparency of the Gel solution obviously changed. The electrolytic dissolution and structural changes of 3DC were further investigated. The results of TOC and TN showed that the organic matter in 3DC was dissolved by electrolysis, and the tissue cavitation was obvious. A new approach for the preparation of collagen-based multi-pore biomaterials by electrochemical method was explored.

Abstract The recycling of leather solid waste not only involves resource utilization and environmental protection but also has important significance for the sustainable development of the leather industry. In this paper, the leather waste was crushed into fibers, which were stabilized and mixed with nitrile-butadiene rubber (NBR). The mixture was milled and vulcanized and a composite NBR-SLF (Stabilized Leather Fiber) is prepared for sealing material. The physical and mechanical properties, water resistance, oil resistance and aging resistance of NBR-SLF were tested and analyzed. It is found that the optimized NBR-SLF not only reduces the cost of raw material, but also changes the physical and mechanical performance of NBR. As a sealing material, it satisfies the substitution of NBR in terms of hardness and thermal stability. Especially the anti-aging ability is better than NBR. Graphical abstract

Abstract Background Human naïve pluripotency state cells can be derived from direct isolation of inner cell mass or primed-to-naïve resetting of human embryonic stem cells (hESCs) through different combinations of transcription factors, small molecular inhibitors, and growth factors. Long noncoding RNAs (lncRNAs) have been identified to be crucial in diverse biological processes, including pluripotency regulatory circuit of mouse pluripotent stem cells (PSCs), but few are involved in human PSCs’ regulation of pluripotency and naïve pluripotency derivation. This study initially planned to discover more lncRNAs possibly playing significant roles in the regulation of human PSCs’ pluripotency, but accidently identified a lncRNA whose knockdown in human PSCs induced naïve-like pluripotency conversion. Methods Candidate lncRNAs tightly correlated with human pluripotency were screened from 55 RNA-seq data containing human ESC, human induced pluripotent stem cell (iPSC), and somatic tissue samples. Then loss-of-function experiments in human PSCs were performed to investigate the function of these candidate lncRNAs. The naïve-like pluripotency conversion caused by CCDC144NL-AS1 knockdown (KD) was characterized by quantitative real-time PCR, immunofluorescence staining, western blotting, differentiation of hESCs in vitro and in vivo, RNA-seq, and chromatin immunoprecipitation. Finally, the signaling pathways in CCDC144NL-AS1-KD human PSCs were examined through western blotting and analysis of RNA-seq data. Results The results indicated that knockdown of CCDC144NL-AS1 induces naïve-like state conversion of human PSCs in the absence of additional transcription factors or small molecular inhibitors. CCDC144NL-AS1-KD human PSCs reveal naïve-like pluripotency features, such as elevated expression of naïve pluripotency-associated genes, increased developmental capacity, analogous transcriptional profiles to human naïve PSCs, and global reduction of repressive chromatin modification marks. Furthermore, CCDC144NL-AS1-KD human PSCs display inhibition of MAPK (ERK), accumulation of active β-catenin, and upregulation of some LIF/STAT3 target genes, and all of these are concordant with previously reported traits of human naïve PSCs. Conclusions Our study unveils an unexpected role of a lncRNA, CCDC144NL-AS1, in the naïve-like state conversion of human PSCs, providing a new perspective to further understand the regulation process of human early pluripotency states conversion. It is suggested that CCDC144NL-AS1 can be potentially valuable for future research on deriving higher quality naïve state human PSCs and promoting their therapeutic applications.

Parkinson’s disease (PD) is an age-related and second most common neurodegenerative disorder. In recent years, increasing evidence revealed that peripheral immune cells might be able to infiltrate into brain tissues, which could arouse neuroinflammation and aggravate neurodegeneration. This study aimed to illuminate the landscape of peripheral immune cells and signature genes associated with immune infiltration in PD. Several transcriptomic datasets of substantia nigra (SN) from the Gene Expression Omnibus (GEO) database were separately collected as training cohort, testing cohort, and external validation cohort. The immunoscore of each sample calculated by single-sample gene set enrichment analysis was used to reflect the peripheral immune cell infiltration and to identify the differential immune cell types between PD and healthy participants. According to receiver operating characteristic (ROC) curve analysis, the immunoscore achieved an overall accuracy of the area under the curve (AUC) = 0.883 in the testing cohort, respectively. The immunoscore displayed good performance in the external validation cohort with an AUC of 0.745. The correlation analysis and logistic regression analysis were used to analyze the correlation between immune cells and PD, and mast cell was identified most associated with the occurrence of PD. Additionally, increased mast cells were also observed in our in vivo PD model. Weighted gene co-expression network analysis (WGCNA) was used to selected module genes related to a mast cell. The least absolute shrinkage and selection operator (LASSO) analysis and random-forest analysis were used to analyze module genes, and two hub genes RBM3 and AGTR1 were identified as associated with mast cells in the training cohort. The expression levels of RBM3 and AGTR1 in these cohorts and PD models revealed that these hub genes were significantly downregulated in PD. Moreover, the expression trend of the aforementioned two genes differed in mast cells and dopaminergic (DA) neurons. In conclusion, this study not only exhibited a landscape of immune infiltrating patterns in PD but also identified mast cells and two hub genes associated with the occurrence of PD, which provided potential therapeutic targets for PD patients (PDs).

Abstract Background Cofactor engineering is involved in the modification of enzymes related to nicotinamide adenine dinucleotides (NADH and NAD+) metabolism, which results in a significantly altered spectrum of metabolic products. Cofactor engineering plays an important role in metabolic engineering but is rarely reported in the sterols biotransformation process owing to its use of multi-catabolic enzymes, which promote multiple consecutive reactions. Androst-4-ene-3, 17-dione (AD) and androst-1, 4-diene-3, 17-dione (ADD) are important steroid medicine intermediates that are obtained via the nucleus oxidation and the side chain degradation of phytosterols by Mycobacterium. Given that the biotransformation from phytosterols to AD (D) is supposed to be a NAD+-dependent process, this work utilized cofactor engineering in Mycobacterium neoaurum and investigated the effect on cofactor and phytosterols metabolism. Results Through the addition of the coenzyme precursor of nicotinic acid in the phytosterols fermentation system, the intracellular NAD+/NADH ratio and the AD (D) production of M. neoaurum TCCC 11978 (MNR M3) were higher than in the control. Moreover, the NADH: flavin oxidoreductase was identified and was supposed to exert a positive effect on cofactor regulation and phytosterols metabolism pathways via comparative proteomic profiling of MNR cultured with and without phytosterols. In addition, the NADH: flavin oxidoreductase and a water-forming NADH oxidase from Lactobacillus brevis, were successfully overexpressed and heterologously expressed in MNR M3 to improve the intracellular ratio of NAD+/NADH. After 96 h of cultivation, the expression of these two enzymes in MNR M3 resulted in the decrease in intracellular NADH level (by 51 and 67%, respectively) and the increase in NAD+/NADH ratio (by 113 and 192%, respectively). Phytosterols bioconversion revealed that the conversion ratio of engineered stains was ultimately improved by 58 and 147%, respectively. The highest AD (D) conversion ratio by MNR M3N2 was 94% in the conversion system with soybean oil as reaction media to promote the solubility of phytosterols. Conclusions The ratio of NAD+/NADH is an important factor for the transformation of phytosterols. Expression of NADH: flavin oxidoreductase and water-forming NADH oxidase in MNR improved AD (D) production. Besides the manipulation of key enzyme activities, which included in phytosterols degradation pathways, maintenance the balance of redox also played an important role in promoting steroid biotransformation. The recombinant MNR strain may be useful in industrial production.

Abstract A highly sensitive fiber-optic accelerometer based on detecting the power output of resonances from the core dip is demonstrated. The sensing probe comprises a compact structure, hereby a short section of specific core (with a significant core dip) fiber stub containing a straight fiber Bragg grating is spliced to another single-mode fiber via a core self-alignment process. The femtosecond laser side-illumination technique was utilized to ensure that the grating inscription region is precisely positioned and compact in size. Two well-defined core resonances were achieved in reflection: one originates from the core dip and the other originates from fiber core. The key point is that only one of these two reflective resonances exhibits a high sensitivity to fiber bend (and vibration), whereas the other is immune to it. For low frequency (

An optical fiber Fabry-Perot interferometer (FPI) based on poly (ethyleneimine) (PEI)/ poly (vinyl alcohol) (PVA) blend membrane is proposed and realized experimentally as a sensor for the pressure of CO2 in the atmosphere. The functional material layer based on PEI/PVA blend polymer exhibits reversible optical path difference change because of absorption and release of CO2 gas molecules. The cavity of the FPI is fabricated by coating a 15-μm PEI/PVA blend film on the end-face of a cleaved single-mode fiber. An interference spectrum with fringe contrast of 19.5 dB and free spectra range of 33.15 nm is obtained. The proposed FPI sensor is sensitive to the changes of concentration of CO2, as well as a sensitivity of 0.281 nm/% within an interval which ranges from 7.6% to 86.9%.

An easily multiplexed fiber-optic Fabry-Perot interferometer (FPI)-based ultrasonic wave (UW) sensor has been proposed and used to experimentally demonstrate ultrasound wave imaging of seismic-physical models. The sensor probe comprises an interferometer formed by a free-standing gold foil and a cleaved optic-fiber tip. An acoustic focusing lens enhances the sensor's ultrasound sensitivity and assists with capability to multiplex multiple probes. Theoretical modeling of the focusing effect of the acoustic lenses and the ultrasonic responses of the probes are presented and analyzed. We present an experimental demonstration of time-division multiplexing of three fiber-optic Fabry-Perot sensors operating in air to reconstruct the shapes of physical models. The compact sensor has a symmetrical structure so that it presents a good directionality of ultrasound detection, making it valuable as an effective sensor for ultrasound scanning of physical models in air.

A miniature optical fiber ultrasonic sensor based on the Fabry-Perot interferometer (FPI) is proposed and experimentally demonstrated. The cavity of the interferometer is based on a section of hollow core fiber coated with a 353ND diaphragm. A well-define interference pattern is achieved, and the spectral sideband filter technique is used to interrogate the sensor. Because the thin reflective diaphragm is extremely sensitive to sound pressure, the signal-to-noise ratio of the sensor response reaches to 31.22 dB with the pulse ultrasonic excitation of 300 kHz. A clear interface information can be distinguished in physical model imaging, and the longitudinal spatial resolution is 5 mm. This proposed sensor has the advantages of being simple to fabricate, ultracompact in size, cost effective, corrosion resistance, and being highly stable.

A fringe visibility enhanced fiber-optic Fabry-Perot functionalized diaphragm based ultrasonic sensor is proposed and experimentally demonstrated for ultrasound sensing. [...]

A fiber-optic Fabry-Perot interferometer (FPI) has been proposed and demonstrated for the ultrasound wave (UW) imaging of seismic-physical models. The sensor probe comprises a single mode fiber (SMF) that is inserted into a ceramic tube terminated by an ultra-thin gold film. The probe performs with an excellent UW sensitivity thanks to the nanolayer gold film, and thus is capable of detecting a weak UW in air medium. Furthermore, the compact sensor is a symmetrical structure so that it presents a good directionality in the UW detection. The spectral band-side filter technique is used for UW interrogation. After scanning the models using the sensing probe in air, the two-dimensional (2D) images of four physical models are reconstructed.

With the oil and gas industry growing rapidly, increasing the yield and profit require advances in technology for cost-effective production in key areas of reservoir exploration and in oil-well production-management. In this paper we review our group’s research into fiber Bragg gratings (FBGs) and their applications in the oil industry, especially in the well-logging field. FBG sensors used for seismic exploration in the oil and gas industry need to be capable of measuring multiple physical parameters such as temperature, pressure, and acoustic waves in a hostile environment. This application requires that the FBG sensors display high sensitivity over the broad vibration frequency range of 5 Hz to 2.5 kHz, which contains the important geological information. We report the incorporation of mechanical transducers in the FBG sensors to enable enhance the sensors’ amplitude and frequency response. Whenever the FBG sensors are working within a well, they must withstand high temperatures and high pressures, up to 175 °C and 40 Mpa or more. We use femtosecond laser side-illumination to ensure that the FBGs themselves have the high temperature resistance up to 1100 °C. Using FBG sensors combined with suitable metal transducers, we have experimentally realized high- temperature and pressure measurements up to 400 °C and 100 Mpa. We introduce a novel technology of ultrasonic imaging of seismic physical models using FBG sensors, which is superior to conventional seismic exploration methods. Compared with piezoelectric transducers, FBG ultrasonic sensors demonstrate superior sensitivity, more compact structure, improved spatial resolution, high stability and immunity to electromagnetic interference (EMI). In the last section, we present a case study of a well-logging field to demonstrate the utility of FBG sensors in the oil and gas industry.