Welding seam tracking based on online programming is the future trend of intelligent production. However, most of the existing image processing methods have certain limitations in the adaptability, accuracy, and robustness of weld feature point detection. The online welding method of gas metal arc welding (GMAW) based on active vision sensing is studied in this paper. The Steger sub-pixel detection method is used to guarantee the accuracy of feature point extraction, and a self-adaptive search window and self-adaptive slope extraction are proposed on this basis. The self-adaptive window is generated according to the linear information of the weld area, and the scale factor and range threshold constraint are added to realize the real-time detection of the weld feature information. Screening the center pixel of the laser stripe in the self-adaptive window of the current frame by the initial slope or the self-adaptive slope of the previous frame, the linear information of the weld area is obtained. The self-adaptive slope of the current frame is fitted by the random sampling consistency method, and the pixel margin is retained to adapt to the linear detection of different continuous welds. When arc light and other serious interference make it difficult to obtain weld information, a particle filter is used to make the best prediction of the weld position. Finally, the welding robot platform based on laser vision sensing was built to test various continuous welds of the butt weld, fillet weld, and lap weld. Experimental results show that the detection speed is 27 ms, and the accuracy of detection and tracking can respectively reach 0.03 mm and 0.78 mm, which meets the requirements of weld detection and tracking.
OBJECTIVES: To evaluate the methodological quality of randomized controlled trials (RCTs) of traditional Chinese medicines for the treatment of gastric precancerous lesions in the past 20 years. METHODS: The RCTs on traditional Chinese medicines for gastric precancerous lesions were searched from the CNKI, Wanfang database, VIP, PubMed, and Embase from January 2001 to December 2021. The retrieved articles were screened, extracted and evaluated based on the 2010 edition of CONSORT statement, Cochrane Risk of Bias Assessment Scale and additional evaluation indicators. RESULTS: A total of 840 papers were included. According to the Cochrane Risk of Bias Assessment Scale, the high risk of bias in the application of randomized methods was 5.95%; the risk of uncertainty for the allocation scheme concealment was 98.93%; the risk of uncertainty for blinding of patients or testers was 98.69%; the risk of uncertainty for blinding of the outcome assessor was 100.00%; the risk of bias for completeness of the outcome data was 2.86%; and the risk of uncertainty for selective reporting was 98.45%. The CONSORT statement evaluating the quality of reporting showed that 100.00% of the RCT articles reported the 8 entries; 36.79% of the literature mentioned the method of randomized sequence generation, but only 27.62% of the literature mentioned who implemented the randomized program, 1.07% of the literature hid the randomized program and 1.31% of the studies were blinded; 36.67% of the literature reported adverse reactions; no literature reported sample size prediction methods. Additional evaluation indicators showed that 17.02% of the studies had ethical approval; 43.81% of the literature specified Chinese medicine evidence; 16.55% of the studies excluded severe heterotrophic hyperplasia; 7.26% of the studies conducted follow-up; and 65.12% of the literature used composite efficacy indicators; 46.67% of the literature applied pathological histological evaluation; 2.62% of the literature applied quality of life evaluation. CONCLUSIONS: The overall risk of bias in RCTs of traditional Chinese medicines for gastric precancerous lesions is high, and the quality of most of the study reports needs to be improved. In the future, it is necessary to strengthen the study design of RCTs and refer to appropriate traditional Chinese medicines evidence grading standards, select study protocols according to different purposes, provide objective and strong evidence for clinical studies on traditional Chinese medicines, and carry out clinical study design and result reporting suitable for traditional Chinese medicines according to the CONSORT principle.
Medicine, Chinese Traditional , Precancerous Conditions , Humans , Randomized Controlled Trials as Topic , Precancerous Conditions/drug therapy
The ambient stability and processability of organic solar cells (OSCs) are important factors for their commercialization. Herein, we selected four benzo[1,2-b:4,5-b']difuran (BDF) polymers and two electron acceptors to examine the role of photovoltaic materials in the ambient stability. The investigations revealed that the MoOx layer is the detrimental factor for the ambient stabilities. The penetration of MoOx into the active layer and their interactions will strengthen the interface and form a favorable contact, hence leading to the increased photovoltaic performance, in which the efficiency loss induced by air was balanced out. As such, these BDF polymer-based non-fullerene (NF) OSCs possessed very promising ambient stabilities even after â¼1000 h with the almost maintained power conversion efficiencies (PCEs). These results drive us to further investigate the ambient processability of these NF-OSCs. The PCEs from the devices processed under ambient condition only possessed 0.3-2% loss compared to those devices under inert conditions, which suggest the significant potentials of BDF polymers to develop highly efficient and stable NF-OSCs for the practical applications.
The rapid response movement caused by the Marangoni effect, a surface tension gradient-induced mass transfer behavior, has spurred considerable promise for diverse applications from microrobots and microreactors to smart drug delivery. Herein, we fabricated an aligned hollow fiber swimmer that showed self-propel movement on a water surface based on the Marangoni effect. By rational designing of an aligned hollow microstructure and an optimized geometrical shape, this swimmer can move continuously for more than 600 s and the maximum angular velocity can reach 22 rad·s-1. The movement process of the swimmer is clearly monitored by infrared imaging and the process fluid migration. Moreover, this swimmer exhibited a highly controllable motion mode induced by a magnetic field and a concentration gradient. We designed a novel continuous motion system under the heat conversion from solar energy illumination into mechanical energy. This swimmer shows potential application prospects in controlled cargo transportation and convenient energy conversion systems.
Wearable and stretchable electronics including various conductors and sensors are featured with their lightweight, high flexibility, and easy integration into functional devices or textiles. However, most flexible electronic materials are still unsatisfactory due to their poor recoverability under large strain. Herein, we fabricated a carbon nanotubes (CNTs) and polyurethane (PU) nanofibers composite helical yarn with electrical conductivity, ultrastretchability, and high stretch sensitivity. The synergy of elastic PU molecules and spring-like microgeometry enable the helical yarn excellent stretchability, while CNTs are stably winding-locked into the yarn through a simple twisting strategy, making good conductivity. By virtue of the interlaced conductive network of CNTs in microlevel and the helical structure in macrolevel, the CNTs/PU helical yarn achieves good recoverability within 900% and maximum tensile elongation up to 1700%. With these features, it can be used as a superelastic and highly stable conductive wire. Moreover, it also can monitor the human motion as a rapid-response strain sensor by adjusting the content of the CNTs simply. This general and low-cost strategy is of great promise for ultrastretchable wearable electronics and multifunctional devices.
Single pure organic molecular white light emitters (SPOMWLEs) are of significance as a new class of material for white lighting applications; however, few of them are able to emit white electroluminescence from organic light-emitting diodes. Herein, donor-π-acceptor conjugated emitters, 2PQ-PTZ and 4PQ-PTZ, were designed and synthesized as SPOMWLEs for white light emission considering the distinct advantages of their conformation isomers. The coexistence of conformational isomers in 2PQ-PTZ, which is the first experimental evidence of the coexisting quasi-axial and quasi-equatorial conformers, provides ideal flexibility to obtain white light emission from their simultaneous and well-separated fluorescence and thermally activated delayed fluorescence. With these remarkable properties, a 2PQ-PTZ-based white light-emitting diode (LED) with a CIE of (0.32, 0.34) and color rendering index (CRI) of 89 is demonstrated. Further, the white organic light-emitting diode (OLED) of 2PQ-PTZ exhibits a high external quantum efficiency (EQE) of 10.1%, which is the reported highest performance among SPOMWLE-based OLEDs.
Achieving efficient ultralong purely organic phosphorescent luminophores is still a big challenge due to the slow intersystem crossing (ISC) process. Herein, we present a facile molecular design strategy that incorporates a secondary group (Br atom or methoxy group) into o-BrCz that can significantly enhance the ISC rate constant (kISC) and achieve high phosphorescence quantum yields (ΦP). As a result, DBrCz and MeBrCz achieved a profound increase of kISC ≈ 108 s-1 and obtained excellent ΦP values up to 24.53 and 27.81% in solid powder, respectively. Given the highly efficient ΦP and proper τp, DBrCz and MeBrCz are applied to alternating current (AC) light-emitting diodes (LEDs), achieving a white LED with CIE coordinates (0.28, 0.29) and a CRI over 90. As a proof of concept, we demonstrate its compensation effect on the dark duration of AC-LED with a reduced percent flicker of 78%. This result extends a new potential application for RTP luminophores in the lighting field.
A novel fused perylene diimide (PDI)-based polymer electron acceptor (PFPDI-BDF) with a built-in twisting configuration was constructed for application in all-polymer solar cells (all-PSCs). To shed light on the compatibility of the FPDI polymer acceptor and to identify a suitable polymer donor for device applications, we considered herein to investigate three polymer donors (PBDB-T, PTB7-Th, and PCPDTFBT) with different optical and electronic properties as well as polymer chain packing behavior for comparing the device performance. After being fabricated with PFPDI-BDF, polymer donor PBDB-T with a wide band gap showed a decent power conversion efficiency (PCE) of 4.86% with an open-circuit voltage (Voc) of 0.82 V, a short-circuit current density (Jsc) of 8.94 mA cm-2, and a recorded fill factor (FF) of 66.3%, which is one of the best FF reported for PDI-based all-polymer solar cells (all-PSCs). The enhanced efficiency of 6.05% was found in the medium band gap polymer PTB7-Th devices due to the more complementary absorption region that makes the photoactive blends absorb more photons, giving rise to an increased Jsc of 12.97 mA cm-2. On the other hand, due to the inferior exciton dissociation/extraction efficiency and unfavorable morphology compatibility, the narrow band gap polymer donor PCPDTFBT/PFPDI-BDF devices exhibited the worst PCE of only 0.71% with a low Jsc of 2.2 mA cm-2 and a FF of 42.4%.
Two novel benzo[1,2-b:4,5-b' ]difuran (BDF)-based wide-bandgap polymers, PBDFT-FBz and PBDFF-FBz, featuring a difluorobenzotriazole (FBz) acceptor unit, are designed and synthesized. The first attempt through main-chain engineering to alter thiophene units to furan units in the main chain of PBDFT-FBz, and further side-chain engineering eliminate the 2-ethylthiophenyl side chains of PBDFT-FBz by 2-ethylfuryl side chains to generate the "all-furan" polymer PBDFF-FBz. By taking the benefit of the oxygen atom in furan, both PBDFT-FBz and PBDFF-FBz exhibit lower HOMO energy levels and enhanced polymer chain interactions compared to their benzo[1,2-b:4,5-b' ]dithiophene (BDT)-based counterparts. As a result, while applying both polymers in non-fullerene polymer solar cells with non-fullerene acceptor m-ITIC, both devices exhibit highly promising photovoltaic performance. The power conversion efficiency (PCE) in the PBDFT-FBz device reaches 7.57% with increased open circuit voltage (Voc ) and fill factor (FF) compared to the PCE of 5.98% in its BDT counterpart (J52). A further increased PCE is obtained (8.79%) in the PBDFF-FBz:m-ITIC device, which shows ≈47% enhancement in device performance compared to that of J52. The large increase in photovoltaic performance is attributed to the lower-lying HOMO energy levels and better chain interactions in these BDF-based polymers.
Benzofurans/chemistry , Polymers/chemistry , Solar Energy , Electric Power Supplies , Molecular Structure , Polymers/chemical synthesis
Development of microtissues that possess mechanical properties mimicking those of native stretchable tissues, such as muscle and tendon, is in high demand for tissue engineering and regenerative medicine. However, regardless of the significant advances in synthetic biomaterials, it remains challenging to fabricate living microtissue with high stretchability because application of large strains to microtissues can damage the cells by rupturing their structures. Inspired by the hierarchical helical structure of native fibrous tissues and its behavior of nonaffine deformation, we develop a highly stretchable and tough microtissue fiber made up of a hierarchical helix yarn scaffold, scaling from nanometers to millimeters, that can overcome this limitation. This microtissue can be stretched up to 15 times its initial length and has a toughness of 57 GJ m-3 More importantly, cells grown on this scaffold maintain high viability, even under severe cyclic strains (up to 600%) that can be attributed to the nonaffine deformation under large strains, mimicking native biopolymer scaffolds. Furthermore, as proof of principle, we demonstrate that the nanotopography of the helical nanofiber yarn is able to induce cytoskeletal alignment and nuclear elongation, which promote myogenic differentiation of mesenchymal stem cells by triggering nuclear translocation of transcriptional coactivator with PDZ-binding motif (TAZ). The highly stretchable microtissues we develop here will facilitate a variety of tissue engineering applications and the development of engineered living systems.
Biocompatible Materials/chemistry , Nanofibers/chemistry , Tissue Engineering/instrumentation , Tissue Scaffolds/chemistry , Biocompatible Materials/chemical synthesis , Biomechanical Phenomena , Cell Differentiation , Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/metabolism , Myoblasts/cytology , Myoblasts/metabolism , Myosin Heavy Chains/metabolism
We report three n-type polymeric electron acceptors (PFPDI-TT, PFPDI-T, and PFPDI-Se) based on the fused perylene diimide (FPDI) and thieno[3,2- b]thiophene, thiophene, or selenophene units for all-polymer solar cells (all-PSCs). These FPDI-based polymer acceptors exhibit strong absorption between 350 and 650 nm with wide optical bandgap of 1.86-1.91 eV, showing good absorption compensation with the narrow bandgap polymer donor. The lowest unoccupied molecular orbital (LUMO) energy levels were located at around -4.11 eV, which are comparable with those of the fullerene derivatives and other small molecular electron acceptors. The conventional all-PSCs based on the three polymer acceptors and PTB7-Th as polymer donor gave remarkable power conversion efficiencies (PCEs) of >6%, and the PFPDI-Se-based all-PSC achieved the highest PCE of 6.58% with a short-circuit current density ( Jsc) of 13.96 mA/cm2, an open-circuit voltage ( Voc) of 0.76 V, and a fill factor (FF) of 62.0%. More interestingly, our results indicate that the photovoltaic performances of the FPDI-based polymer acceptors are mainly determined by the FPDI unit with a small effect from the comonomers, which is quite different from the others reported rylenediimide-based polymer acceptors. This intriguing phenomenon is speculated as the huge geometry configuration of the FPDI unit, which minimizes the effect of the comonomer. These results highlight a promising future for the application of the FPDI-based polymer acceptors in the highly efficient all-PSCs.
Near-infrared fluorescent probes are important and interesting for advanced biological and biomedical applications where the fluorescence technology is employed. Herein, we reported high near-infrared (NIR) fluorescent conjugated polymer dots (Pdots) of two polymers (PTPE-DTNT2 and PTPE-DTNT4) with cross-conjugated aggregation-induced emission fluorogen as the side chain. The photoluminescent quantum yields (PLQYs) of Pdots were up to 31.8% with the near-infrared emission peak of 716 nm, which is among the best values of NIR Pdots reported so far. In addition, Pdots possessed a dual-color emission feature. Thus, dual-color cellular imaging with both Pdots was demonstrated in biological applications; to the best of our knowledge, this is the first reported dual-color cellular imaging with Pdots. The NIR Pdots were also applied in in vivo cytotoxicity analysis and microangiography imaging of zebrafish. We anticipate that NIR Pdots with their dual-color feature will find broad applications in multiplexed biological and biomedical fields.
Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications. Inspired by the stomatal closure feature of plant leaves at relatively high temperature, here we report a nano-gating membrane with a negative temperature-response coefficient that is capable of tunable water gating and precise small molecule separation. The membrane is composed of poly(N-isopropylacrylamide) covalently bound to graphene oxide via free-radical polymerization. By virtue of the temperature tunable lamellar spaces of the graphene oxide nanosheets, the water permeance of the membrane could be reversibly regulated with a high gating ratio. Moreover, the space tunability endows the membrane with the capability of gradually separating multiple molecules of different sizes. This nano-gating membrane expands the scope of temperature-responsive membranes and has great potential applications in smart gating systems and molecular separation.
The first hyperbranched BODIPY-based conjugated polymer dots (Pdots) were reported. The Pdots showed quantum yields of as high as 22%, which is 40% higher than their linear counterparts. The Pdots were successfully applied in cell-labelling applications. These results demonstrated that hyperbranched polymers are a very promising material for biological imaging and applications.
Boron Compounds/pharmacology , Fluorescent Dyes/pharmacology , Polymers/pharmacology , Quantum Dots/chemistry , Animals , Boron Compounds/chemical synthesis , Boron Compounds/chemistry , Boron Compounds/toxicity , Cell Line, Tumor , Fluorenes/chemical synthesis , Fluorenes/chemistry , Fluorenes/pharmacology , Fluorenes/toxicity , Fluorescence , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/chemistry , Fluorescent Dyes/toxicity , Humans , Microscopy, Confocal/methods , Molecular Structure , Polymers/chemical synthesis , Polymers/chemistry , Polymers/toxicity , Quantum Dots/toxicity , Streptavidin/chemistry , Thiadiazoles/chemical synthesis , Thiadiazoles/chemistry , Thiadiazoles/pharmacology , Thiadiazoles/toxicity , Zebrafish
Human natural blood vessels have a three-layer structure including the tunica intima, tunica media, and tunica adventitia. These subtle structures endow healthy blood vessels with outstanding strength, elasticity, and compliance as well as excellent haemodynamic and anti-thrombus performance. Fabrication of a next generation vascular graft that mimics the structures and functions of natural blood vessels is becoming the pursuit of biomaterials and medical scientists. Here we fabricate a bio-inspired nanofiber three-layer vascular graft by electrospinning. The inner PLA/PCL layer is favorable for adhesion of human umbilical vein endothelial cells that could accelerate endothelialization. The middle PU/PCL layer provides superior mechanical properties (63.40 MPa, 266.78% in the longitudinal direction and 52.34 MPa, 319.72% in the lateral direction). The outer PLA/PCL layer with circumferentially aligned fibers is beneficial for guiding vascular smooth muscle cells in the circumferentially oriented direction. The bio-inspired three-layer vascular graft with strong mechanical properties and good cell biocompatibility will play an important role in vessel remodeling and regeneration.
The separation of organic liquid mixtures is achieved by Cu(OH)2 nanoneedle-covered copper mesh based on the difference of the liquid surface tension. The as-prepared membrane allows the penetration of organic liquid with smaller surface tension and blocks the higher. Thus, the effective separation of these two organic liquids can be achieved.
Vertically aligned rutile TiO2 nanowire arrays (NWAs) with lengths of â¼44 µm have been successfully synthesized on transparent, conductive fluorine-doped tin oxide (FTO) glass by a facile one-step solvothermal method. The length and wire-to-wire distance of NWAs can be controlled by adjusting the ethanol content in the reaction solution. By employing optimized rutile TiO2 NWAs for dye-sensitized solar cells (DSCs), a remarkable power conversion efficiency (PCE) of 8.9% is achieved. Moreover, in combination with a light-scattering layer, the performance of a rutile TiO2 NWAs based DSC can be further enhanced, reaching an impressive PCE of 9.6%, which is the highest efficiency for rutile TiO2 NWA based DSCs so far.
Cells are trapped: The 3D fibrous interfaces, including microfibers, nanofibers, and nanofibers/microbeads composite interfaces, are fabricated by electrospinning. After coated with anti-EpCAM, these 3D fibrous interfaces allow cancer cells to be firmly trapped into the networks that show the outstanding capability for cancer cell capture from real blood.
Biosensing Techniques , Neoplasms/pathology , Tissue Scaffolds , Humans , MCF-7 Cells
In order to improve the solubility of doped nanoparticles in solutions, Y(2)O(3):Tm(3+)/Yb(3+) nanoparticles were synthesized using the Pechini-type sol-gel method, and their surfaces were modified with amino or carboxylic functional groups using ligand-capped and ligand-exchanging methods. The nanoparticles with modified surfaces were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and zeta potential (ζ), and their photoluminescence was studied by fluorescence spectrophotometry. The results indicate that the upconversion fluorescence of amine- and carboxyl-modified nanoparticles was enhanced after the surfaces of nanoparticles were modified. Compared to the upconversion fluorescence intensity of non-modified nanoparticles, the upconversion fluorescence intensities of amine- and carboxyl-modified nanoparticles were enhanced by 9.4 and 1.4 times, respectively. These results are attributed to the formation of the chemical bonds between Y(2)O(3):Tm(3+)/Yb(3+) core and non-crystalline SiO(2) shell via Y-O-Si bridges, which activate the 'dormant' Tm(3+)/Yb(3+) ions on the surfaces of nanoparticles. The results of the solubility investigations for amine- and carboxyl-modified nanoparticles indicate that severe aggregation can be weakened by adhering amino or carboxylic functional groups to the surfaces of nanoparticles. It is therefore concluded that the good hydrophilicity resulting from active functional groups in solutions and more intense upconversion fluorescence enable the doped core-shell nanoparticles to have great potential to be used as fluorescence biolabels in the future.
In order to improve the photoluminescence property of Eu(3+)-doped nanoparticles, Y(2)O(3):Eu(3+) nanoparticles were synthesized using the Pechini-type sol-gel method, then coated with SiO(2) shells by using the Stöber method for different coating times. The SiO(2)-coated nanoparticles were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, and their photoluminescence spectra were recorded under 800 nm femtosecond laser excitation. The results indicate that a two-photon simultaneous absorption upconversion luminescence is obtained, and their upconversion luminescence intensities are further enhanced after the surfaces of the nanoparticles are coated with different thickness SiO(2) shells. Compared to the upconversion luminescence intensity of non-coated nanoparticles at 611 nm, the upconversion luminescence intensities of SiO(2)-coated Y(2)O(3):Eu(3+) nanoparticles with coating times of 60, 90 and 120 min were enhanced by 3.30, 3.96 and 4.13 times, respectively. This can be attributed to the contributions of the increased amounts of Eu(3+) ions populated at the (5)D(0) level on the surfaces of the nanoparticles because the cooperative ligand fields between the Y(2)O(3) core and non-crystalline SiO(2) shell interfaces activate the 'dormant' Eu(3+) ions near or on the surfaces of the nanoparticles. From a Judd-Ofelt (J-O) theory analysis, the coated shell structures can improve the radiative quantum efficiencies of Eu(3+)-doped nanoparticles. It is therefore concluded that more intense red upconversion luminescence with high radiative quantum efficiencies can enable the SiO(2)-coated Y(2)O(3):Eu(3+) nanoparticles to have the great potential to be used as a fine resolution phosphor.
