Photoplethysmography-based cuffless blood pressure estimation: an image encoding and fusion approach.

Objective.Photoplethysmography (PPG) is a promising wearable technology that detects volumetric changes in microcirculation using a light source and a sensor on the skin's surface. PPG has been shown to be useful for non-invasive blood pressure (BP) measurement. Deep learning-based BP measurements are now gaining popularity. However, almost all methods focus on 1D PPG. We aimed to design an end-to-end approach for estimating BP using image encodings from a 2D perspective.Approach.In this paper, we present a BP estimation approach based on an image encoding and fusion (BP-IEF) technique. We convert the PPG into five image encodings and use them as input. The proposed BP-IEF consists of two parts: an encoder and a decoder. In addition, three kinds of well-known neural networks are taken as the fundamental architecture of the encoder. The decoder is a hybrid architecture that consists of convolutional and fully connected layers, which are used to fuse features from the encoder.Main results.The performance of the proposed BP-IEF is evaluated on the UCI database in both non-mixed and mixed manners. On the non-mixed dataset, the root mean square error and mean absolute error for systolic BP (SBP) are 13.031 mmHg and 9.187 mmHg respectively, while for diastolic BP (DBP) they are 5.049 mmHg and 3.810 mmHg. On the mixed dataset, the corresponding values for SBP are 4.623 mmHg and 3.058 mmHg, while for DBP the values are 2.350 mmHg and 1.608 mmHg. In addition, both SBP and DBP estimation on the mixed dataset achieved grade A compared to the British Hypertension Society standard. The DBP estimation on the non-mixed dataset also achieved grade A.Significance.The results indicate that the proposed approach has the potential to improve on the current mobile healthcare for cuffless BP measurement.

Study on the Actuation Properties of Polyurethane Fiber Membranes Filled with PEG-SWNTs Dielectric Microcapsules.

Polyurethane dielectric elastomer (PUDE), a typical representative of emerging intelligent materials, has advantages, such as good elasticity and flexibility, fast response speed, high electromechanical conversion efficiency, and strong environmental tolerance. It has promising applications in underwater bionic actuators, but its electromechanical properties should be improved further. In this context, the design of polyethylene glycol (PEG) single-walled carbon nanotube (SWNTs) dielectric microcapsules was adopted to balance the problem of contradictions, which conventional dielectric modification methods face between comprehensive properties (e.g., dielectric properties and modulus). Moreover, the dielectric microcapsule was evenly filled into the polyurethane fiber by coaxial spinning technology to enhance the actuation performance and instability of the electrical breakdown threshold of conventional polyurethane dielectric modification. It was revealed that the dielectric microcapsules were oriented in the polyurethane fiber, and the actuation performance of the composite fiber membrane was significantly better than that of the polyurethane fiber membrane filled with SWNTs, thus confirming that the filling design of the dielectric microcapsules in polyurethane fiber could have certain technical advantages. On that basis, this study provides a novel idea for the dielectric modification of polyurethane.

The Effect of a Flexible Electrode on the Electro Deformability of an Actuating Unit of a MDI-Polyurethane Composite Fiber Membrane Filled with BaTiO3.

The electro deformability of an actuating unit of a polyurethane dielectric elastomer (PUDE) is affected by many factors. The agglomeration of dielectric fillers faced by the traditional dielectric modification methods will lead to the instability of the actuation performance of dielectric composites. In addition, the electro deformability (ability of deformation after voltage loading) is great affected by the selection of flexible electrodes and packaging technology. Based on the research findings, Diphenylmethane-4,4'-diisocyanat (MDI)-polyurethane dielectric composite fiber membrane filled with barium titanate (BaTiO3) is prepared using coaxial spinning, and this study then analyzes the effects of the types of flexible electrodes and coating methods on the electro deformability of the actuating unit of the dielectric composite fiber membrane. It is found that the electro deformability of the actuating unit coated with the single-walled carbon nanotube (SWNT) flexible electrode is better than that of the perfluoropolyether conductive grease (PCG) or the traditional conductive carbon grease (CCG) electrode in various degrees. When the loading voltage is 20 kV, the electro deformability of the actuating unit coated with SWNT flexible electrode exceeds the latter two electrodes by 13.8%; when the SWNT flexible electrode is encapsulated by physical surface implantation (PSI), the electric deformation of the actuating unit is higher than that of the solvent suspension dispersion (SSD).

Preparation and Dielectric Sensitivity of Polyurethane Composite Fiber Membrane Filled with BaTiO3.

Polyurethane dielectric elastomer (PUDE) is considered a potential underwater flexible actuator material due to its excellent designability and environmental tolerance at the molecular level. Currently, the application of the polyurethane elastomer as an actuating material is constrained by such problems as the conflict between various properties such as dielectric properties and modulus and the low level of dielectric sensitivity. This is a common challenge facing polyurethane dielectric research related to the uneven distribution of dielectric fillers in the matrix. Besides, another challenge for the academic circles is the easy agglomeration of micro and nanofillers. Given the above-mentioned background of the application and technical problems, the coaxial electrospinning technology is proposed in this paper. The polyurethane fiber network is constructed with the preferred hydrolysis resistant polyether-Diphenylmethane diisocyanate (MDI) thermoplastic polyurethane elastomer as the matrix material. Dispersed by ultrasound, the micro nano dielectric filler is integrated into polyurethane fiber through the coaxial dual-channel design. Additionally, directional constraint molding is conducted to improve the agglomeration of small-scale particles induced by the loss of mechanical energy in traditional blending. After characterization, the distribution of BaTiO3 particles in the fiber bundle is relatively uniform. Compared to the polyurethane dielectric composites prepared by traditional blending (BaTiO3-Dielectric Elastomer, BaTiO3-DE), the dielectric sensitivity factor of the polyurethane composite fiber membrane (BaTiO3-Dielectric Elastomer Membrane, BaTiO3-DEM) is enhanced by over 25%; the electrostrictive strain of BaTiO3-DEM is boosted by least 10%.

The Synergistic Effect of WS2 and SWNTs on Tribological Performance of Polyether MDI Polyurethane Elastomer under Dry and Wet Friction Conditions.

To adapt to the complex application of polyurethane bearings, it is feasible to improve the tribological performance of single polyurethane-based friction materials through the synergistic effect produced by multi-component-lubricating fillers. In this context, rather than using tungsten disulfide (WS2), which has demonstrated excellent self-lubricating performance as a lubricating oil additive, this paper proposes that WS2 and single-walled carbon nanotubes (SWNTs) can be designed for addition into a polyether 4,4'-diphenylmethane diisocyanate (MDI) polyurethane matrix as self-lubricating fillers so as to explore the synergistic effect of micro- and nano-lubricating fillers on the tribological performance of polyurethane matrix materials. Through a series of characterizations and tests, it was found that the dispersion of two-component-lubricating additives in a polyurethane matrix is improved when the ratio of WS2 to SWNTs is roughly 2:1. In this case, the tribological performance of polyurethane matrix composites is more satisfactory than at other ratios. In addition, compared with the blank sample, the tribological performance of the synergistically modified polyurethane composites under dry friction is more significantly improved with the increase in contact load, while there is no significant improvement under water lubrication. Aside from contributing to the idea of exploring the synergistic effect of WS2 and other micro or nanofillers, this method also opens up the possibility of practically applying WS2 in the field of friction.

Biological Process of Alkane Degradation by Gordonia sihwaniensis.

With the development of the petroleum industry, oil pollution has become widespread. It is harmful to the digestive, immune, reproductive, and nervous systems of fishes, wild animals, and humans, causing severe threats to ecological safety and human health. Gordonia has increasingly attracted attention in the treatment of alkane pollution for its outstanding performance against hydrophobic refractory substances. However, the lack of knowledge about alkane uptake and degradation restricts the application of gordonia. In this paper, we studied the strain lys1-3 of Gordonia sihwaniensis isolated from coal chemical wastewater, which showed good alkane degradation performance by lys1-3. It is found that stimulated by an alkane, lys1-3 secreted biosurfactants, which emulsified large alkane particles to smaller particles. By active transport, unmodified alkane was transferred into cells and produced a large amount of acid, which was secreted out of the cells.

Genome-Wide Association Study of QTLs Conferring Resistance to Bacterial Leaf Streak in Rice.

Bacterial leaf streak (BLS) is a devastating rice disease caused by the bacterial pathogen, Xanthomonas oryzae pv. oryzicola (Xoc), which can result in severe damage to rice production worldwide. Based on a total of 510 rice accessions, trialed in two seasons and using six different multi-locus GWAS methods (mrMLM, ISIS EM-BLASSO, pLARmEB, FASTmrMLM, FASTmrEMMA and pKWmEB), 79 quantitative trait nucleotides (QTNs) reflecting 69 QTLs for BLS resistance were identified (LOD > 3). The QTNs were distributed on all chromosomes, with the most distributed on chromosome 11, followed by chromosomes 1 and 5. Each QTN had an additive effect of 0.20 (cm) and explained, on average, 2.44% of the phenotypic variance, varying from 0.00-0.92 (cm) and from 0.00-9.86%, respectively. Twenty-five QTNs were detected by at least two methods. Among them, qnBLS11.17 was detected by as many as five methods. Most of the QTNs showed a significant interaction with their environment, but no QTNs were detected in both seasons. By defining the QTL range for each QTN according to the LD half-decay distance, a total of 848 candidate genes were found for nine top QTNs. Among them, more than 10% were annotated to be related to biotic stress resistance, and five showed a significant response to Xoc infection. Our results could facilitate the in-depth study and marker-assisted improvement of rice resistance to BLS.