CO2 activation and fixation: highly efficient syntheses of hydroxy carbamates over Au/Fe2O3

This paper reports an effective route for the syntheses of hydroxy carbamates from the reaction of CO2, epoxides and amines catalyzed by a Au/Fe2O3 catalyst. Under the optimized reaction conditions, various hydroxy carbamates were successfully synthesized with 92-98% isolated yields. The catalyst could be reused for several runs without deactivation. A plausible reaction mechanism was proposed by which the hydroxy carbamate was formed through an ammonium carbamate intermediate and the catalyst mainly promoted further nucleophilic addition between the epoxide and ammonium carbamate

Seismic Performance of Precast Concrete Column-to-Column Joint Using the Steel Plate Hoop and Bolts Connection

The traditional precast concrete column-to-column connections are widely used in the prefabricated concrete frame structures in China. However, many studies on the column-to-column joints have demonstrated their complex forms and poor construction efficiency. To overcome these shortcomings, a new type column–column connection with steel plate hoop and bolts was designed and proposed. In order to reveal the seismic performance of this new type connection, four precast concrete columns and two cast-in-situ columns were tested by cyclic lateral loading. They were compared and analyzed from the aspects of test phenomenon, failure mode, load–displacement relationship, strength, and stiffness degradation. The results showed that the prefabricated columns with this new type connection had the same seismic performance as the cast-in-place columns. Additionally, the strain curves of longitudinal reinforcement, stirrups, and steel plate hoops were presented, and the force transmission mode of this novel connection was analyzed. The results indicated that the innovative connection had reliable force transmission mode, which can provide reference for the application of prefabricated frame structure in the earthquake area

Investigations on Pressure Fluctuations in the S-Shaped Region of a Pump–Turbine

Hydraulic pumped storage is a special power generation and electricity shortage technology, which is usually operated with thermal power and nuclear power units, and plays a key role in ultra-high voltage and smart grid. Pressure fluctuations are the main reasons for the instability of the S-shaped region of pump–turbines, which seriously affects their lifespan and operation stability. To reveal the mechanism and propagation law of pressure fluctuations in the S-shaped region as well as numerical simulations at the turbine, the braking and the reverse pump operating conditions of a pump–turbine were carried out. Numerical results were validated using the performance experiments, and the generation mechanism and propagation law of pressure fluctuation were analyzed in detail. The analyses show that high-amplitude pressure fluctuations mainly occur in the braking and reverse pump operating conditions. Under the braking condition, a 0.49-fn low-frequency pressure fluctuation was captured, which is caused by the rotation of the backflow in the vanes. Under the reverse pump condition, a 0.19-fn low-frequency pressure fluctuation was confirmed, which is caused by the periodic rotation of the vortex between the vaneless space. This study has important guiding significance for practical engineering application

Multi-parameter e-skin based on biomimetic mechanoreceptors and stress field sensing

Abstract Tactile sensing has been a key challenge in robotic haptics. Inspired by how human skin sense the stress field with layered structure and distributed mechanoreceptors, we herein propose a design for modular multi-parameter perception electronic skin. With the stress field sensing concept, complex tactile signals can be transformed into field information. By analyzing the stress field, the real-time three-dimensional forces can be resolved with 1.8° polar angle resolution and 3.5° azimuthal angle resolution (achieved up to 71 folds of improvement in spatial resolution), we can also detect the hardness of object in contact with the electronic skin. Moreover, we demonstrate random assembly of the sensing arrays and integration of our electronic skin onto differently curved surfaces do not lead to any measurement variation of the stress field. This result reveals that the sensing elements in our electronic skin system can be modularly made and exchanged for specific applications

Piezoresistive relaxation and creep model of porous polymer nanocomposite supported by experimental data

Porous piezoresistive nanocomposites (PPNs), a blend of conductive nanomaterials and a porous polymer matrix, have garnered significant attention in the realm of flexible pressure sensors. The porous microstructure offers exceptional sensitivity and lightweight characteristics of these sensors, but it also introduces challenges such as relaxation and creep behaviors. Grounded in viscoelastic theory, this paper introduces a mathematical model that provides a quantitative analysis of the resistance-strain relationship of PPN-based piezoresistive sensors, considering both bulk resistance and contact resistance. To elucidate the relaxation and creep behaviors, the model incorporates the conformational change and the slip motion of the polymer macromolecules during the deformation. Utilizing the Adam optimization algorithm, the model can accurately depict the piezoresistive behavior of various PPNs (with different porosities and conductive nanomaterial contents) with a fitting accuracy exceeding 99%. Furthermore, we explored some atypical characteristics of the PPN-based sensor, such as the negative resistance-strain behavior and the overshooting of bulk resistance. This study sets a theoretical basis for the development of sensitive and stable PPN-based sensors

Porous nanocomposites with enhanced intrinsic piezoresistive sensitivity for bioinspired multimodal tactile sensors

Abstract In this work, we propose porous fluororubber/thermoplastic urethane nanocomposites (PFTNs) and explore their intrinsic piezoresistive sensitivity to pressure. Our experiments reveal that the intrinsic sensitivity of the PFTN-based sensor to pressure up to 10 kPa increases up to 900% compared to the porous thermoplastic urethane nanocomposite (PTN) counterpart and up to 275% compared to the porous fluororubber nanocomposite (PFN) counterpart. For pressures exceeding 10 kPa, the resistance-pressure relationship of PFTN follows a logarithmic function, and the sensitivity is 221% and 125% higher than that of PTN and PFN, respectively. With the excellent intrinsic sensitivity of the thick PFTN film, a single sensing unit with integrated electrode design can imitate human skin for touch detection, pressure perception and traction sensation. The sensing range of our multimodal tactile sensor reaches ~150 Pa, and it exhibits a linear fit over 97% for both normal pressure and shear force. We also demonstrate that an electronic skin, made of an array of sensing units, is capable of accurately recognizing complex tactile interactions including pinch, spread, and tweak motions

Squamous differentiation in patients with superficial bladder urothelial carcinoma is associated with high risk of recurrence and poor survival

Abstract Background The independent prognostic role of squamous differentiation in pT1 bladder urothelial carcinoma has not been reported in previous studies. This article describes the impact of squamous differentiation on tumor recurrence and survival, and whether this histologic variant could indeed alter definitive treatment, based on single center-based retrospective data. Methods Totally, we retrieved (1)1449 histologically confirmed pT1 bladder urothelial carcinoma patients without histologic variants; (2)227 pT1 bladder urothelial carcinoma patients with squamous differentiation in our institution, from May 2004 to Oct 2015. The total amount of high/low grade urothelial carcinoma patients was 991/685 respectively. Transurethral resection of bladder tumor (TURBT) and intravesical chemotherapy were performed as initial treatments for all the patients. The clinical and pathological characteristics, treatment and survival outcomes were compared between squamous differentiation-positive and squamous differentiation-negative patients. Results In our study, 14% urothelial carcinoma patients were detected with squamous differentiation. The mean age of all the patients examined was 66.4, of whom 82% were males. The 5-year cancer specific survival rates were 69% for squamous differentiation-positive patients and 91% for squamous differentiation-negative patients (p < 0.001). Recurrence proved to be more common in squamous differentiation-positive patients than in negative patients. In the results of the univariate and multivariate Cox proportional hazard analysis, tumor size, lymphovascular invasion, recurrence and squamous differentiation were confirmed to be the prognostic factors associated with patients’ survival. Conclusions Squamous differentiation in pT1 bladder urothelial carcinoma is correlated to high risk of recurrence and poor prognosis as an independent prognostic factor. Radical cystectomy is essential for recurred high grade pT1 bladder urothelial carcinoma with squamous differentiation accompanied by lymphovascular invasion

ITIH4: A New Potential Biomarker of “Toxin Syndrome” in Coronary Heart Disease Patient Identified with Proteomic Method

Objective. This trial aims to look for the protein biomarker of “toxin syndrome” of CHD patients. Methods. We have performed two trials in this paper. The first trial was a randomized controlled trial (RCT) of the plasma proteome in unstable angina (UA) patients by Maldi-Tof Mass. The second trial was a nested case-control study in 1503 stable CHD patients with one-year followup for acute cardiovascular events (ACEs). Results. In the RCT study, 12 protein spots were found to be the differential protein for the significant differences between the difference of before and after treatment in group A and group B; 2 of them (3207.37 Da and 4279.95 Da) was considered to be unique to “toxin syndrome” for being differential proteins of group B but not group A. These 2 spots were identified as Isoform 1 of Fibrinogen alpha chain precursor (FGA, 3207.37 Da) and Isoform 2 of inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4, 4279.95 Da), respectively. In the nested case-control study, the result of Western blot demonstrated that protein expression of ITIH4 in the group with followup ACEs was significantly lower than the matched group without followup ACEs (P=0.027). Conclusion. ITIH4 might be a new potential biomarker of CHD “toxin syndrome” in TCM, indicating the potential role in early identifying high-risk CHD patients in stable period

KIF20A Affects the Prognosis of Bladder Cancer by Promoting the Proliferation and Metastasis of Bladder Cancer Cells

Objective. To investigate the expression of kinesin family member 20A (KIF20A) in bladder cancer, the effect of KIF20A on the proliferation and metastasis of bladder cancer cells, and the effect of KIF20A expression on the prognosis of bladder cancer patients. Methods. Bladder cancer tissue and its adjacent tissues were collected from tumour patients. The mRNA and protein expression levels of KIF20A in the tissue samples were detected by qRT-PCR and western blot. Immunohistochemical (IHC) staining was used to identify the expression and distribution of KIF20A proteins in the tissue samples. The relationship between the KIF20A expression and the clinical pathology of bladder cancer was analysed. The effect of the differential expression of KIF20A on the prognosis of patients with bladder cancer was analysed by the TCGA database. The plasmid was transfected into the bladder cell lines T24 and 5637 to construct two stable cell lines with knocked down KIF20A. The effect of KIF20A expression on the proliferation and invasion of T24 and 5637 bladder cells was explored in vitro using the abovementioned stable cell lines. The effect of the KIF20A expression on the proliferation of bladder cancer cells was evaluated by a mouse xenograft model. Results. The expression of KIF20A was significantly higher in the bladder cancer tissues than in the adjacent control tissues. The expression of KIF20A was significantly associated with the degree of pathological differentiation of bladder cancer. Patients with a higher expression of KIF20A had a higher tumour grade and a more advanced stage. The mean survival of patients with a high KIF20A expression was significantly lower than the mean survival of patients with a low KIF20A expression. The in vitro experiments demonstrated that the knockdown of KIF20A significantly inhibited T24 and 5637 cell proliferation and invasion. The in vivo experiments showed that the knockdown of KIF20A significantly inhibited the proliferation of the bladder tumours. Conclusion. KIF20A promotes the proliferation and metastasis of bladder cancer cells. Bladder cancer patients with a high KIF20A expression have a worse tumour differentiation and a poor prognosis. KIF20A may become an independent factor that affects the prognosis of bladder cancer patients and a therapeutic target for bladder cancer

Efficient and reversible absorption of ammonia by cobalt ionic liquids through Lewis acid-base and cooperative hydrogen bond interactions

Ammonia (NH3) emissions have caused a wide range of environmental problems and serious harm to human health. However, efficiently separating NH3 and simultaneously recovering high purity NH3 easily remains a great challenge. A new strategy to design transition metal ionic liquids (MILs) by combining specific metal centers and ligands with ILs was proposed for efficient and reversible absorption of NH3. Not only exceptional NH3 absorption capacity and high NH3/CO2 selectivity, but also excellent recyclability were achieved by cobalt ILs [C(n)mim](2)[Co(NCS)(4)]. The maximal capacity of NH3 is up to 6.09 mol NH3 mol IL-1 at 30 degrees C and 0.10 MPa, which is much higher than all reported ILs to date, and is over 30 times higher than the conventional ILs [C(n)mim][SCN]. The superior NH3 capacity and desorption performance originate from the moderate Lewis acid-base and cooperative hydrogen bond interactions between the metal center-ligands and NH3.</p