The semicrystalline polymer incorporated with nanofillers frequently exhibits complicated crystallization behavior, which is probably attributed to the nanofiller-constructed complex crystalline ...circumstance, especially a confined space. In the present work, in order to have a thorough understanding of biodegradable poly(l-lactic acid) (PLLA) crystallization behavior on the dependence of graphene oxide nanosheet (GONS) loadings, in particular the relatively high GONS loading, a set of GONS/PLLA nanocomposites with different GONS loadings ranging from 0 to 4.0 wt % were investigated in terms of isothermal crystallization behavior by differential scanning calorimetry and time-resolved Fourier-transform infrared spectroscopy techniques. The results indicated that GONSs not only served as heterogeneous nucleating agents for PLLA crystallization but also restricted the mobility and diffusion of PLLA chains. At low GONS concentrations of 0.25 and 0.5 wt %, GONSs acted as a temple for PLLA chains to land on due to extremely high specific surface area, thus promoting the conformational ordering and reducing the nucleating barrier. The nucleation effect of GONSs was dominant to achieve accelerated overall crystallization kinetics. As the GONS concentration rose up to 1.0 wt %, the GONS network was formed in the PLLA matrix, which was verified by solid-like rheological behavior at low frequencies in rheological measurement. The nanofiller network significantly constrained the mobility and diffusion of PLLA chains and offset the nucleation effect of GONSs, giving rise to a turning point in crystallization rate from promotion to restriction. Furthermore, a severely confined space was constructed by the more crowded and denser GONS networks at a higher GONS concentration of 4.0 wt %, compelling PLLA lamellae to grow in a two-dimensional mode. The unusual crystallization behavior of PLLA from promotion to restriction was also understood by the four-region model, in which the semiquantitative description of crystalline circumstance was provided. These results pave an effective way to further reveal the crystallization behavior of polymer at a relatively high nanofiller loading.
Aims/Introduction
Evidence has shown that stressful life events are associated with the development of diabetes, yet studies in mainland China are scarce. In the present study, we explored the ...associations between cumulative and specific stressful life events and the prevalence of diabetes in Chinese adults.
Materials and Methods
The cross‐sectional data were from the China Kadoorie Biobank study, which enrolled approximately 500,000 adults aged 30–79 years from 10 diverse regions of China. Logistic regression models were used to calculate the adjusted odds ratio (OR) and the 95% confidence interval (CI).
Results
Of the 473,607 participants, 25,301 (5.34%) had type 2 diabetes (2.68% clinically‐identified and 2.66% screen‐detected). Participants who experienced one and two or more stressful life events were 1.10‐fold (OR 1.10, 95% CI 1.05–1.16) and 1.33‐fold (OR 1.33, 95% CI 1.13–1.57) more likely to have type 2 diabetes. Three categories of work‐related events (OR 1.15, 95% CI 1.01–1.31), as well as family‐related events (OR 1.11, 95% CI 1.06–1.18) and personal‐related events (OR 1.18, 95% CI 1.03–1.36), were associated with an increased likelihood of type 2 diabetes. Regarding the specific life events, the ORs of loss of job or retirement, as well as major conflict within family, death or major illness of other close family member and major injury or traffic accident, were 1.24 (95% CI 1.02–1.52), 1.24 (95% CI 1.08–1.43), 1.13 (95% CI 1.06–1.20) and 1.20 (95% CI 1.01–1.43), respectively.
Conclusions
The present study showed that cumulative and specific stressful life events were significantly associated with an increased prevalence of diabetes.
Evidence has shown that stressful life events are associated with the development of diabetes, yet studies in mainland China are scarce. The present study showed that cumulative and specific stressful life events were significantly associated with an increased prevalence of diabetes.
Hepcidin is a key regulator of iron homeostasis. Some studies showed that exogenous hepcidin decreased the expression of divalent metal transporter (DMT1) rather than ferroportin(FPN1) to regulate ...renal iron metabolism. This study explored the effects of hepcidin synthesized by the kidney and its mechanism of iron regulation.
In the in vivo experiments, mice were divided into a unilateral ureter obstruction (UUO) model group and a sham operation group, and mice in the UUO model group were sacrificed on days 1, 3, 5 and 7. The expression of renal hepcidin, FPN1, DMT1 and the retention of renal iron were studied. In the in vitro experiments, we overexpressed hepcidin in HK-2 cells. Then we tested the expression of renal hepcidin, FPN1, DMT1 and observed the production of intracellular ferrous ions.
Renal hepcidin expression was consistently higher in the UUO group than in the sham group from the first day. The expression of FPN1 gradually decreased, and the expression of DMT1 gradually increased in the UUO model. Intracellular ferrous ions significantly increased on the first day of the UUO model. In hepcidin overexpressed HK-2 cells, the expression of FPN1 was decreased, while the expression of DMT1 has no significant change. In addition, production of intracellular ferrous ions increased.
Conclusion: local hepcidin can regulate iron metabolism in the kidney by adjusting the expression of FPN1.
•First, build up kidney cell-specific (HK-2 cell) hepcidin-overexpressed model.•Second, local hepcidin regulates iron metabolism in the kidney by adjusting the expression of FPN1, whereas exogenous hepcidin reduces the expression of DMT1.•Third, co-fluorescence staining of hepcidin and ferrous ions showed renal iron accumulation closely related to local hepcidin.
A novel visible-light-induced radical cascade bromocyclization of N-arylacrylamides has been accomplished. This reaction overcomes the overbromination at the benzene rings suffered in traditional ...electrophilic reactions, thus enabling the first highly chemoselective synthesis of valuable 3-bromomethyloxindoles. The combination of pyridine and anhydrous medium is identified as the key factor for the high chemoselectivity in the current photoreaction system, which might work by suppressing the in situ generation of low-concentration Br2 from N-bromosuccinimide. Moreover, the mild reaction conditions ensure the generation of a wide range of the new desired products with excellent functional group tolerance.
Edge computing, especially multiaccess edge computing, is seen as a promising technology to improve the Quality of user Experience (QoE) of many artificial intelligence (AI) applications in the ...evolution toward Internet-of-Things (IoT) infrastructure. However, the management and deployment of massive edge data centers bring new challenges for the current network. In this article, we propose a new edge-based IoT platform for AI (EBI-PAI), based on software-defined network (SDN) and serverless technology. EBI-PAI provides a unified service calling interface and schedules the resources automatically to satisfy the QoE requirements of users. To optimize performances during incremental deployment, we formulate the deployment problem, prove its complexity, and design heuristic algorithms to solve it. We implement EBI-PAI based on an opensource serverless project and deploy it in real networks. To evaluate EBI-PAI, we conduct comprehensive simulations based on the generated and real-world network topology, and real-world base station data set. The simulation results show that EBI-PAI can greatly improve QoE with the same budget and save the budget to achieve similar QoE. We finally carry out a case study with real user demands, and it further validates the simulation results.
Online social media today has a large number of users and has become a huge platform to collect and share the social data generated by the end users. In addition, based on the development of social ...applications, the social sensing system has been greatly developed to generate, transmit, and store, which is helping the prosperous of the social computing systems. However, the violation of the security of end users' social data stored and shared through the social computing system becomes a serious and urgent issue. The data protection on social media platforms is very different compared with the scenario of the traditional encryption algorithms, and most of the existing schemes are not suitable for data protection in the current social sensing and data-sharing system. In this article, we present a novel design based on the agnostic selective encryption concept to efficiently protect the social data based on the embedded block coding with optimized truncation system. By selectively encrypting only a small portion of the bitstreams in the middle layer of this coding system, a high level of protection and efficiency can both be achieved. We also experiment with our method on four common social data formats, and the security analysis tests are performed to verify the high protection level of our method.
This work placed an emphasis that constructing segregated boron nitride (BN)/carbon nanotube (CNT) hybrid network brought an immense benefit to enhance the thermal conductivity (TC) of ...poly(vinylidene fluoride) (PVDF) composites. The segregated composites ((CNT + BN)@PVDF) showed a high TC of 1.8 W/mK at the total filler fraction of 25 vol %, outperforming PVDF composites with random structure (CNT/BN/PVDF) and segregated BN structure (BN@PVDF) by 169% and 50%, respectively. Infrared thermal images further demonstrated that (CNT + BN)@PVDF exhibited superior capability to dissipate heat compared to BN/PVDF. The segregated architecture increased the effective utilization of fillers and interfacial thermal resistance between neighboring BN platelets was reduced by the bridging effect of CNTs. Molding pressure and temperature governed the integration of segregated networks and thus the enhancement efficiency of TC. The design of hybrid segregated structure holds promise in a broad range of the preparation of thermal management materials.
A simple and sensitive high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method has been developed and validated for simultaneous quantification of five local anesthetics in ...human plasma: procaine, lidocaine, ropivacaine, tetracaine and bupivacaine. In an ice-water bath, 500
μL plasma sample, containing 100
μg/mL neostigmine methylsulfate as anticholinesterase, was spiked with carbamazepine as internal standard and alkalized by sodium hydroxide. Liquid–liquid extraction with ethyl ether was used for plasma sample preparation. The chromatographic separation was achieved on a Kromosil ODS C18 column with a mobile phase consisting of 30
mM potassium dihydrogen phosphate buffer (0.16% triethylamine, pH adjusted to 4.9 with phosphoric acid) and acetonitrile (63/37, v/v). The detection was performed simultaneously at wavelengths of 210 and 290
nm. The chromatographic analysis time was 13
min per sample. The calibration curves of all five analytes were linear between 0.05 and 5.0
μg/mL (
r
2
≥
0.998). Precision ranged from 1.4% to 7.9% and accuracy was between 91.7% and 106.5%. The validated method is applicable for simultaneous determination of procaine, lidocaine, ropivacaine, tetracaine and bupivacaine for therapeutic drug monitoring and pharmacokinetic study.
In this work, the effect of expandable graphite (EG) and ammonium polyphosphate (APP) on the flame retardancy and mechanical properties of the rigid polyurethane foam (RPUF) was studied. The results ...indicated that both EG and APP could effectively improve the flame retardancy of RPUF, while the retardancy of EG was better than APP. When the flame-retardant loading was 15 wt %, the limited oxygen index (LOI) values of APP- and EG-filled RPUF were 24.5 and 32 vol %, respectively. According to the LOI test, the optimal ratio of APP to EG in RPUF composites was 1 : 1 by weight, at which the LOI value of 15 wt % (APP + EG)/RPUF was 30.5 vol %. Thermal degradation test of RPUF composites by thermogravimetric analysis indicated that the addition of APP and EG to RPUF could lead to an increase in the amount of high-temperature residue. Under the same conditions, the residue amount of EG/RPUF was less than that of APP/RPUF at the same temperature. Compression test and dynamic thermal mechanical analysis indicated that both the compressive strength and modulus decreased at a certain extent with the EG- or APP-filled into RPUF, respectively, but with the mixture of EG and APP added into RPUF, the mechanical properties of these materials increased.
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