Reconfiguration, Welding, Reprogramming, and Complex Shape Transformation of An Optical Shape Memory Polymer Network Enabled by Patterned Secondary Crosslinking.

Stimuli-triggered generation of complicated 3D shapes from 2D strips or plates without using sophisticated molds is desirable and achieving such 2D-to-3D shape transformation in combination with shape reconfiguration, welding, and reprogramming on a single material is very challenging. Here, a convenient and facile strategy using the solution of a disulfide-containing diamine for patterned secondary crosslinking of an optical shape-memory polymer network is developed to integrate the above performances. The dangling thiolectones attached to the backbones react with the diamine in the solution-deposited region so that the secondary crosslinking may not only weld individual strips into assembled 3D shapes but also suppress the relaxation of the deformed polymer chains to different extents for shape reconfiguration or heating-induced complex 3D deformations. In addition, as the dynamic disulfide bonds can be thermally activated to erase the initial programming information and the excessive thiolectones are available for subsequent patterned crosslinking, the material also allows shape reprogramming. Combining welding with patterning treatment, it is further demonstrated that a gripper can be assembled and photothermally controlled to readily grasp an object.

Hierarchical Magnetic Carbon Nanoflowers for Ultra-Efficient Electromagnetic Wave Absorption.

Porous carbon nanomaterials are widely applied in the electromagnetic wave absorption (EMWA) field. Among them, an emerging flower-like carbon nanomaterial, termed carbon nanoflowers (CNFs), has attracted tremendous research attention due to their unique hierarchical flower-like structure. However, the design of flower-like carbon nanomaterials with different magnetic cores for EMWA has rarely been reported. Herein, a general template method is proposed to achieve a set of high-quality magnetic CNFs, namely Co@Void@CNFs, CoNi@CNFs, and Ni@CNFs. The prepared magnetic CNFs have highly accessible surface area and internal space, rich heteroatom content, multi-scale pore system, and uniform and highly dispersed magnetic nanoparticles, as a result, deliver superior EMWA performance. Specifically, when the thickness is 2.6 mm, the Co@Void@CNFs exhibit a maximum refection loss (RLmax) of -56.6 dB and an effective absorption bandwidth (EAB) from 8.0 to 12.1 GHz covering the whole X band. The CoNi@CNFs have an RLmax of up to -57.6 dB and a wide EAB of 5.6 GHz at just 1.9 mm. For the Ni@CNFs, possess an ultra-broad EAB of 6.1 GHz, covering the entire Ku band at 2.0 mm. Overall, the hierarchical magnetic carbon nanoflowers proposed here offer new insights toward realizing multifunctional integrated carbon nanomaterials for EMWA.

Sequentially Controlled Recognition of Different Proteins Using Programmable Protein Imprinted Nanospheres.

Although protein imprinted materials with multiple templates are developed to selectively separate different proteins, it is difficult to achieve the programmed adsorption and separation of different proteins using one material, because the available protein imprinted materials are constructed through irreversible crosslinking and their structures are unprogrammable and non-reconstructive. Herein, a novel nanosphere (MS@PTL-g-PNIPAM) is designed, which not only is temperature and pH responsive but also can dynamically reversibly crosslink/de-crosslink under ultraviolet light of different wavelengths. With the help of the dynamically reversible photo-crosslinking, the nanospheres can be repeatedly programmed into protein imprinted nanospheres toward different target proteins. Moreover, the prepared imprinted nanospheres can easily achieve the controlled rebinding and release of target proteins, benefiting from the introduced temperature- and pH-responsive moieties. As a consequence, this study realizes the specific separation of different target proteins from protein mixture and the real bovine blood sequentially by programming one material. It is resource saving, time saving, recyclable, and it will provide convenience for protein imprinted materials to use in the blood purification, drug delivery, and virus detection.

Exosomes from human urine-derived stem cells carry NRF1 to alleviate bladder fibrosis via regulating miR-301b-3p/TGFßR1 pathway.

Bladder outlet obstruction (BOO) is a common disease that always make the bladder develops from inflammation to fibrosis. This study was to investigate the effect of exosomes from human urine-derived stem cells (hUSCs) on bladder fibrosis after BOO and the underlying mechanism. The BOO mouse model was established by inserting a transurethral catheter, ligation of periurethral wire, and removal of the catheter. Mouse primary bladder smooth muscle cells (BSMCs) were isolated and treated with TGFß1 to mimic the bladder fibrosis model in vitro. Exosomes from hUSCs (hUSC-Exos) were injected into the bladder of BOO mice and added into the culture of TGFß1-induced BSMCs. The associated factors in mouse bladder tissues and BSMCs were detected. It was confirmed that the treatment of hUSC-Exos alleviated mouse bladder fibrosis and down-regulated fibrotic markers (a-SMA and collagen III) in bladder tissues and TGFß1-induced BSMCs. Overexpression of NRF1 in hUSC-Exos further improved the effects of hUSC-Exos on bladder fibrosis both in vivo and in vitro. TGFßR1 was a target of NRF1 and miR-301b-3p, and miR-301b-3p was a target of NRF1. It was next characterized that hUSC-Exos carried NRF1 to up-regulate miR-301B-3p, thereby reducing TGFßR1level. Our results illustrated that hUSC-Exos carried NRF1 to alleviate bladder fibrosis through regulating miR-301b-3p/TGFßR1 pathway.

Efficacy and Safety of Sacral Neuromodulation by Converting Constant Frequency Stimulation Into Variable Frequency Stimulation in Patients With Detrusor Overactivity and Impaired Contractility: A Single-Center Prospective Study.

OBJECTIVES: In patients with detrusor overactivity with impaired contractility (DOIC), it is difficult to relieve abnormal lower urinary tract symptoms during both storage and voiding using sacral neuromodulation (SNM) with constant frequency stimulation (CFS). We sought to evaluate the efficacy and safety of SNM using variable frequency stimulation (VFS) in patients with DOIC by comparing it with outcomes of SNM with CFS. MATERIALS AND METHODS: Between September 2020 and May 2021, we prospectively enrolled 20 patients with DOIC, confirmed on urodynamic examination, and administered SNM with VFS. The patients were followed up and required to maintain voiding diaries and record scale scores of overactive bladder symptoms, psychology and quality of life, uroflowmetry, ultrasonic postvoid residual urine, and adverse events at baseline and during the CFS and VFS phases. RESULTS: The average testing phase was 26.3 ± 4.1 days. Compared with baseline values, overactive bladder symptom, psychologic health questionnaire, and quality of life scores, in addition to voiding frequency, urgency incontinence frequency, daily catheterization volume of voiding diary, and ultrasonic postvoid residual (PVR) decreased significantly during both the CFS and VFS phases (p < 0.05). The average voided volume, functional bladder capacity, and maximum urine flow rate significantly increased during the CFS and VFS phases (p < 0.05). In the VFS phase, voiding frequency, urgency incontinence frequency, daily catheterization volume of voiding diary, and ultrasonic PVR further decreased (p < 0.05), whereas functional bladder capacity, maximum urine flow rate, quality of life score, overactive bladder symptom score, and psychologic health questionnaire score further improved compared with results obtained in the CFS phase (p < 0.05). In the VFS phase, the success rate of further improvement of symptoms was 85.0%, and no new complications were noted. CONCLUSIONS: SNM that converts CFS into VFS may be an effective treatment option for patients with DOIC, exhibiting no increase in adverse events.

All-Organic Superhydrophobic Coating Comprising Raspberry-Like Particles and Fluorinated Polyurethane Prepared via Thiol-Click Reaction.

Mechanically robust superhydrophobic coatings have been extensively reported using chemically susceptible inorganic fillers like slica, titanium dioxide, and zinc oxide for constructing micro-nano structures. Organic particles are good candidates for improving chemical resistance, whereas the synthesis of organic particles with well-defined and stable micro-nano structures remains exclusive. Here, an all-organic, cross-linked superhydrophobic coating comprising raspberry-like fluorinated micro particles (RLFMP) and fluorinated polyurethane (FPU) is prepared via thiol-click reaction. Benefiting from the robust micro-nano structure of RLFMP and the excellent flexibility of FPU, the coating can maintain superhydrophobicity after severe alkali corrosion or mechanical damage, while the superhydrophobicity can be repaired readily by the fast recovery of micro-nano roughness and migration of branched fluoroalkyl chains to the coating surface. This design strategy is expected to provide a good application of thiol-click chemistry.

Nocturnal atmospheric chemistry of NO3 and N2O5 over Changzhou in the Yangtze River Delta in China.

Comprehensive observations of the nocturnal atmospheric oxidation of NO3 and N2O5 were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy (CRDS) from 27 May to 24 June, 2019. High concentrations of NO3 precursors were observed, and the nocturnal production rate of NO3 was determined to be 1.7 ± 1.2 ppbv/hr. However, the nighttime NO3 and N2O5 concentrations were relatively low, with maximum values of 17.7 and 304.7 pptv, respectively, illustrating the rapid loss of NO3 and N2O5. It was found that NO3 dominated the nighttime atmospheric oxidation, accounting for 50.7%, while O3 and OH only contributed 34.1% and 15.2%, respectively. For the reactions of NO3 with volatile organic compounds (VOCs), styrene was found to account for 60.3%, highlighting its dominant role in the NO3 reactivity. In general, the contributions of the reactions between NO3 and VOCs and the N2O5 uptake to NO3 loss were found to be about 39.5% and 60.5%, respectively, indicating that N2O5 uptake also played an important role in the loss of NO3 and N2O5, especially under the high humidity conditions in China. The formation of nitrate at night mainly originated from N2O5 uptake, and the maximum production rate of NO3- reached 6.5 ppbv/hr. The average NOx consumption rate via NO3 and N2O5 chemistry was found to be 0.4 ppbv/h, accounting for 47.9% of the total NOx removal. The predominant roles of NO3 and N2O5 in nitrate formation and NOx removal in the YRD region was highlighted in this study.

Generation and Release of OH Radicals from the Reaction of H2 O with O2 over Soot.

OH radicals in the air maintain the oxidizing power of the troposphere. A conventional view is that particulate matter (PM) in the atmosphere is a major sink of OH radicals, thereby lowering the oxidizing power of atmosphere in the event of high-level PM. By contrary, our joint experimental/theoretical study reveals a new mechanism for the generation of gaseous OH radicals by carbonaceous soot particles. We show that water and O2 react on carbonaceous surfaces and give rise to gaseous OH radicals under irradiation. With ample delocalized π electrons, carbonaceous surfaces enable the easy desorption of hydroxyl groups to produce gaseous OH radicals, evidenced by direct observation of the steady generation of OH radicals on a carbonaceous surface. Our results reveal a new chemical mechanism for the production of OH radicals.

Dual-fiber point diffraction interferometer to measure the wavefront aberration of an imaging system.

A dual-fiber point diffraction interferometer is built to measure the wavefront aberration of an imaging system with high precision. The optical intensity of the test light and reference light are controlled independently, so that high interference contrast can be obtained. The interferometer has several advantages: high precision, a flexible structure, and a quasi-common optical path. System errors of the interferometer that influence the measurement accuracy are considered and calibrated. In the experiments, a projection lens with numerical aperture of 0.3 is measured. The measured wavefront error is 1.5 nm rms, and the measurement repeatability is 35 pm rms.

Long noncoding RNA PCA3 regulates prostate cancer through sponging miR-218-5p and modulating high mobility group box 1.

OBJECTIVE: The purpose of this study was to investigate the mechanism of long noncoding RNA (lncRNA) prostate cancer antigen 3 (PCA3) in prostate cancer (PCa) via regulating the miR-218-5p/high mobility group box 1 (HMGB1) axis. METHODS: The Cancer Genome Atlas database was used to divide differentially expressed lncRNAs, microRNAs, and messenger RNA (mRNAs). The mRNA expressions of lncRNA PCA3, miR-218-5p, and HMGB1 were determined by reverse transcription polymerase chain reaction. Cell propagation was evaluated using the Cell Counting Kit-8 assay and the apoptotic rate was examined by flow cytometry. Cell migration and invasion were observed through the wound healing assay and transwell assay. Target relationships among PCA3, miR-218-5p, and HMGB1 were validated via dual-luciferase reporter gene assay. A nude mouse model in vivo was designed to evaluate the effect of PCA3 on prostate tumor growth. RESULTS: PCA3 and HMGB1 were high-expressed in PCa, whereas miR-218-5p was low-expressed. PCA3 knockdown or miR-218-5p overexpression suppressed PCa cell proliferation, migration, and invasion, but promoted apoptosis. Besides, targeted relationships and interactions on the expression between miR-218-5p and PCA3 or HMGB1 were elucidated. PCA3 weakened cell viability and mobility whereas induced apoptosis through binding with miR-218-5p. Meanwhile, miR-218-5p also inhibited PCa tumorigenesis via downregulation of HMGB1. Knockdown of PCA3 impeded tumor growth by downregulating its downstream gene HMGB1. CONCLUSIONS: lncRNA PCA3 facilitated PCa progression through sponging miR-218-5p and regulating HMGB1.

Utility of the EORTC risk tables and CUETO scoring model for predicting recurrence and progression in non-muscle-invasive bladder cancer patients treated with routine second transurethral resection.

PURPOSE: Routine second transurethral resection (TUR) for non-muscle-invasive bladder cancer (NMIBC) is common practice in Germany. Applicability of European Organization for Research and Treatment of Cancer (EORTC) and Spanish Urological Club for Oncological Treatment (CUETO) models in NMIBC patients is still controversial. Aim of the study was to assess the performance of EORTC and CUETO predictive models in NMIBC patients treated with second TUR. METHODS: 479 NMIBC patients with routine second TUR were analyzed retrospectively between 2003 and 2011, and investigated with clinical and pathological variables in regard to tumor recurrence and progression. Furthermore, recurrencefree survival (RFS) and progression-free survival (PFS) were evaluated according to EORTC and CUETO, and the discrimination of the models assessed. RESULTS: With a median follow-up of 60 months, prior recurrence rate, grade, and second TUR pathology were independent prognostic factors for the risk of disease recurrence and progression. The concordance index of the EORTC and the CUETO model was 0.563 and 0.516 for recurrence and 0.681 and 0.702 for progression, respectively. The positive pathology after second TUR was significantly associated with risk of disease recurrence and progression. EORTC and CUETO risk models estimated progression better than recurrence, especially with higherscore groups. CONCLUSIONS: Improved predictive tools should be developed for optimal treatment selection.

Pulling with the Pentafluorosulfanyl Acceptor in Push-Pull Dyes.

A new class of push-pull fluorophores featuring the pentafluorosulfanyl (SF5) group as a potent acceptor has been synthesized. Known for its excellent chemical and thermal stability, the unique SF5 functionality is also strongly electron-withdrawing but at the same time highly lipophilic. We report six new fluorescent dyes, which were characterized by UV-vis/fluorescence spectroscopy, single-crystal X-ray diffraction, and cyclic voltammetry. Notable dye properties include large Stokes shifts (>100 nm), pronounced solvatofluorochromic effects arising from intramolecular charge transfer, moderate fluorescence quantum yields in both solutions and thin films, and extensive supramolecular C-H···F interactions in their crystalline states. Reversible mechanofluorochromism was also observed in dye 5, where grinding and fuming of a solid sample gave blue- and red-shifted emissions, respectively. Postfunctionalization of dye 3 to afford a pair of strong visible-light absorbers was also demonstrated.

Compressive holography algorithm for the objects composed of point sources.

A compressive holography algorithm is proposed for the objects composed of point sources in this work. The proposed algorithm is based on Gabor holography, an amazingly simple and effective encoder for compressed sensing. In the proposed algorithm, the three-dimensional sampling space is uniformly divided into a number of grids since the virtual object may appear anywhere in the sampling space. All the grids are mapped into an indication vector, which is sparse in nature considering that the number of grids occupied by the virtual object is far less than that of the whole sampling space. Consequently, the point source model can be represented in a compressed sensing framework. With the increase of the number of grids in the sampling space, the coherence of the sensing matrix gets higher, which does not guarantee a perfect reconstruction of the sparse vector with large probability. In this paper, a new algorithm named fast compact sensing matrix pursuit algorithm is proposed to cope with the high coherence problem, as well as the unknown sparsity. A similar compact sensing matrix with low coherence is constructed based on the original sensing matrix using similarity analysis. In order to tackle unknown sparsity, an orthogonal matching pursuit algorithm is utilized to calculate a rough estimate of the true support set, based on the similar compact sensing matrix and the measurement vector. The simulation and experimental results show that the proposed algorithm can efficiently reconstruct a sequence of 3D objects including a Stanford Bunny with complex shape.

An Efficient Distributed Compressed Sensing Algorithm for Decentralized Sensor Network.

We consider the joint sparsity Model 1 (JSM-1) in a decentralized scenario, where a number of sensors are connected through a network and there is no fusion center. A novel algorithm, named distributed compact sensing matrix pursuit (DCSMP), is proposed to exploit the computational and communication capabilities of the sensor nodes. In contrast to the conventional distributed compressed sensing algorithms adopting a random sensing matrix, the proposed algorithm focuses on the deterministic sensing matrices built directly on the real acquisition systems. The proposed DCSMP algorithm can be divided into two independent parts, the common and innovation support set estimation processes. The goal of the common support set estimation process is to obtain an estimated common support set by fusing the candidate support set information from an individual node and its neighboring nodes. In the following innovation support set estimation process, the measurement vector is projected into a subspace that is perpendicular to the subspace spanned by the columns indexed by the estimated common support set, to remove the impact of the estimated common support set. We can then search the innovation support set using an orthogonal matching pursuit (OMP) algorithm based on the projected measurement vector and projected sensing matrix. In the proposed DCSMP algorithm, the process of estimating the common component/support set is decoupled with that of estimating the innovation component/support set. Thus, the inaccurately estimated common support set will have no impact on estimating the innovation support set. It is proven that under the condition the estimated common support set contains the true common support set, the proposed algorithm can find the true innovation set correctly. Moreover, since the innovation support set estimation process is independent of the common support set estimation process, there is no requirement for the cardinality of both sets; thus, the proposed DCSMP algorithm is capable of tackling the unknown sparsity problem successfully.

Dysfunction of Chloroplast Protease Activity Mitigates pgr5 Phenotype in the Green Algae Chlamydomonas reinhardtii.

Researchers have described protection mechanisms against the photoinhibition of photosystems under strong-light stress. Cyclic Electron Flow (CEF) mitigates electron acceptor-side limitation, and thus contributes to Photosystem I (PSI) protection. Chloroplast protease removes damaged protein to assist with protein turn over, which contributes to the quality control of Photosystem II (PSII). The PGR5 protein is involved in PGR5-dependent CEF. The FTSH protein is a chloroplast protease which effectively degrades the damaged PSII reaction center subunit, D1 protein. To investigate how the PSI photoinhibition phenotype in pgr5 would be affected by adding the ftsh mutation, we generated double-mutant pgr5ftsh via crossing, and its phenotype was characterized in the green algae Chlamydomonas reinhardtii. The cells underwent high-light incubation as well as low-light incubation after high-light incubation. The time course of Fv/Fm values in pgr5ftsh showed the same phenotype with ftsh1-1. The amplitude of light-induced P700 photo-oxidation absorbance change was measured. The amplitude was maintained at a low value in the control and pgr5ftsh during high-light incubation, but was continuously decreased in pgr5. During the low-light incubation after high-light incubation, amplitude was more rapidly recovered in pgr5ftsh than pgr5. We concluded that the PSI photoinhibition by the pgr5 mutation is mitigated by an additional ftsh1-1 mutation, in which plastoquinone pool would be less reduced due to damaged PSII accumulation.

Effects of supplementary Da Dingfeng Zhu therapy on patients with Parkinson's disease of liver-kidney yin deficiency pattern.

BACKGROUND: This study aimed to verify whether the combined use of Da Dingfengzhu and Western medicine in treating Parkinson's disease (PD) can lead to therapeutic efficacy and symptom alleviation, thereby achieving a complementary and synergistic effect. METHODS: In this study, 158 patients were initially enrolled, with 116 eligible patients randomly divided into a control and an observation group. The control group received levodopa/benserazide and pramipexole, while the observation group received Da Dingfengzhu combined with levodopa/benserazide and pramipexole for 12 weeks. Baseline patient characteristics, adverse reactions, and blood samples were collected at baseline and 12 weeks post-treatment. The Unified Parkinson's Disease Rating Scale (UPDRS) was used to assess symptom severity at baseline, four weeks into treatment, and 12 weeks post-treatment. RESULTS: Adverse reactions during treatment were similar in both groups, suggesting that the combined therapy in the observation group did not increase adverse effects. Both groups showed improvements in UPDRS scores, with the observation group displaying more significant symptom alleviation at 4 and 12 weeks. Moreover, the observation group exhibited more pronounced increases in serum neurotrophic factor-3 and dopamine levels and greater reductions in oxidative stress and inflammatory response markers. CONCLUSION: In conclusion, the combination of Da Dingfengzhu with levodopa/benserazide and pramipexole for treating PD shows significant clinical potential and is worthy of broader application.

A three-channel thermal dissociation cavity ring-down spectrometer for simultaneous measurement of ambient total peroxy nitrates, total alkyl nitrates, and NO2.

A newly constructed thermal dissociation cavity ring-down spectrometer (TD-CRDS) for the simultaneous measurement of ambient total peroxy nitrates (ΣPNs, RO2NO2), total alkyl nitrates (ΣANs, RONO2), and NO2 was presented in this work. ΣPNs and ΣANs were detected as NO2 with the CRDS instrument after thermal dissociation. PNs and ANs completely dissociated at 180 °C and 360 °C, with conversion efficiencies of 96 % and 99 %, respectively. The effects of NO2 and NO on measurement in different temperatures and two types of thermal dissociation inlet (TDI) were further explored. The influence of ambient NO2 and NO on PNs and ANs in the improved TDI (TDI-2) was significantly improved. To further enhance the measurement accuracy, the consistency of the observed NO2 in the three channels was tested, which achieved good agreement. The detection limits of the TD-CRDS instrument for NO2, ΣPNs, and ΣANs were determined as 6.5, 6.8, and 8.6 pptv (10 s, 1σ), respectively. Observations of PNs and ANs were conducted in a suburban site in Hefei, China, from September 2-30, 2021, using the TD-CRDS instrument, and the consecutive time series of PNs and ANs were derived, verifying the capability of the TD-CRDS instrument for continuous field observations of ΣPNs and ΣANs.

Functional thiolactone assisted imprinting cavities with abundant amines for strong binding of protein imprinted nanospheres.

In order to develop new protein imprinting polymerization methods and to prepare protein imprinted nanomaterials with high recognition, a novel protein imprinted strategy is developed in this study by using polyethyleneimine (PEI) for aminolysis of tailor-made thiolactone-based functional monomers and crosslinkers on amine-modified magnetic nanospheres in an aqueous medium. The prepared protein imprinted nanospheres can seize BSA templates in the imprinting polymerization process through multiple hydrogen bonds, and hydrophobic and electrostatic interactions. In addition, the aminolysis reaction also generates abundant amide bonds in the imprinting polymer network, which not only enhances the hydrogen bonding interactions between the imprinted nanospheres and BSA but also improves the stability of the imprinting cavities by increasing the rigidity of the polymer chains. Based on the above advantages, the protein imprinted nanospheres show excellent rebinding specificity for BSA, for which the rebinding capacity is up to 505 ± 15 mg g-1 and the imprinting factor is 4.09. The protein imprinted nanospheres exhibit fast adsorption kinetics, outstanding reusability, and can selectively separate BSA from a protein mixture and actual biological samples. The generality of this imprinted method is also verified. Thus, this study will provide a new idea for the design of protein imprinted materials with high recognition.

Decomposition of micromotion at the head-neck interface in total hip arthroplasty during walking.

Fretting corrosion as one of the leading causes for failure of modular hip prostheses has been associated with micromotion at head-neck taper junction. Decomposition of micromotion is helpful to promote the development of more realistic experiments investigating failure mechanisms of the head-neck junction in total hip arthroplasty. The aim of this study was to decompose the complex three-dimensional micromotion at the head-neck junction into multiple fundamental modes, including three translational and three rotational components. A three-dimensional finite element model composed of head-neck junction, liner and acetabular cup with a typical 12/14 taper size, as well as the taper mismatch of -4', was developed during walking. The analysis was divided into three procedures: a) the assembly simulation of the head and neck during surgery, b) verification with a simplified axisymmetric model, and c) three-dimensional modelling under normal walking. This study revealed that the main forms of micromotion contained circumferential, longitudinal micromotion and longitudinal rolling toggling, and were closely related to the state of motion. The maximum translational micromotion was predicted to be 10.9 µm during the walking gait, with the predominant modes of the circumferential translation of 9.6 µm, the longitudinal translation of 5.5 µm and the longitudinal rotation of 0.29° along the taper junction. These findings may provide design considerations for further experimental testing about fretting and facilitate the understanding of the fretting mechanisms in hip prostheses.

Double Modification of Poly(urethane-urea): Toward Healable, Tear-Resistant, and Mechanically Robust Elastomers for Strain Sensors.

Polyurethane elastomers with mechanical robustness, tear resistance, and healing efficiency hold great potential in wearable sensors and soft robots. However, achieving excellent mechanical properties and healable capability simultaneously remains highly desirable but exclusive. Herein, we propose a straightforward procedure for double modification of poly(urethane-urea) (PUU) via thiolactone chemistry, and two different dynamic cross-linking bonds (disulfide linkages and Zn2+/imidazole coordination) are successively incorporated into the side chain of PUU, producing double cross-linking elastomers (PUU-I/Zn-S). The synergy between disulfide linkages and Zn2+/imidazole coordination forms a robust and dynamic network, endowing PUU-I/Zn-S with excellent mechanical and healing properties. The tensile stress, elongation at break, and toughness of the resultant elastomer can reach 44.06 MPa, 1000%, and 181.93 MJ m-3, respectively. Meanwhile, PUU-I/Zn-S exhibits outstanding tearing resistance with a tearing energy of 42.1 kJ m-2. The PUU-I/Zn-S can restore its mechanical robustness after self-healing at room temperature (25 ± 2 °C) or 60 °C and even maintain 91% of its original tensile strength after reprocessing two times. Additionally, PUU-I/Zn-S-based strain sensors are fabricated by introducing conductive nanofillers and demonstrate remarkable sensing capability to diverse human body motions. This work demonstrates a simple and feasible method for the postfunctionalization and enhancement of polyurethane and provides some insights into reconciling the traditional contradictory properties of mechanical robustness and healing efficiency.