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Circulating neutrophil gelatinase-associated lipocalin and gestational diabetes mellitus: a meta-analysis
No full textBackground: Many studies have assessed the role of circulating neutrophil gelatinase-associated lipocalin (NGAL) on the risk of gestational diabetes mellitus (GDM), but the results remain uncertain. Thus, this study aimed to assess the association between NGAL and GDM risk by performing a meta-analysis. Methods: We carried out a systematic search of electronic databases (PubMed, Embase, Wanfang and Chinese National Knowledge Infrastructure databases) to retrieve all related studies. The estimates of standardized mean difference (SMD) and its 95% confidence interval (CI) were calculated in a random-effects model. Between-study heterogeneity was assessed using I-2. Results: Of all included 17 studies, 1080 pregnant women with GDM and 1736 controls were finally included in our analysis. The overall estimate indicated that circulating NGAL levels were higher in the GDM cases comparing to normal pregnant women (SMD: 3.16; 95% CI: 2.28, 4.04; p = 30 years (SMD 4.23 vs. 1.30), and among studies with BMI not matched compared to BMI matched studies (SMD: 4.29 vs. 2.63), but no difference was observed in Caucasian population (SMD: 1.68; 95% CI: -0.68, 3.99; p = 0.157). Conclusion: Our findings show that elevated levels of circulating NGAL might be more likely to be found among GDM women. Circulating NGAL might be a helpful detecting marker for the judgment of the occurrence of GDM. Nevertheless, further prospective studies are needed to assess this potential role
Free-standing laser-induced graphene films for high-performance electromagnetic interference shielding
No full textAlthough laser-induced graphene (LIG) has great advantages in the cost and manufacturing process, it has been seldom reported in the field of electromagnetic interference (EMI) shielding due to its unobtrusive conductivity and the limitation of inherent substrates. In this work, polybenzoxazine is chosen as precursor to fabricate the LIG via a one-step defocused lasing process. As a result of favorable porous structures and high conductivity, the as-produced LIG exhibits the EMI shielding effectiveness up to 24.8 dB in X-band at the thickness of 68 mu m. And the EMI shielding effectiveness of LIG/Fe3O4 composite is increased to 32.7 dB at a smaller thickness of 53 mu m which is obtained by a solvent-free approach. When considering the thickness and lightweight properties, the absolute shielding effectiveness is also surpassing most of the other carbon-based shielding materials. More importantly, taking advantage of the difference in the thermal expansion coefficient of carbon material and polymeric substrate, we develop a rapid quench-peeling (RQP) strategy for the separation of LIG from polymeric substrate to obtain the free-standing LIG film. Moreover, the structures and properties of LIG are well preserved. The free-standing LIG films after peeling have wider adaptability in practical EMI shielding applications, and also opened up possibilities for use in other fields, such as Joule heating device. (C) 2021 Elsevier Ltd. All rights reserved
Effect of the modulation geometry on mechanical and tribological properties of TiSiN/TiAlN nano-multilayer coatings
No full textNano-multilayer architecture based on physical vapor deposition is a promising way to tailor the structural and mechanical properties of nitride hard coatings for cutting tool applications. In this work, the mechanical and tribological properties of TiSiN/TiAlN coatings with different modulation geometry, namely modulation period, Lambda, and modulation ratio, lambda, were elaborated. The TiSiN/TiAlN nano-multilayer with reduced Lambda of 8.5 nm and lambda of 1:2.3 (thickness ratio of TiAlN to TiSiN sublayer) shows a noticeable increase in hardness to 36.8 GPa. The modulation geometry impacts the wear behavior of TiSiN/TiAlN nano-multilayers through two aspects. Firstly, the mechanical enhancement effectively promotes the wear resistance of coatings at room temperature. Secondly, the chemical variation changes the wear mechanism at high temperatures. For the situation at 600 degrees C, the combined action of adhesive, abrasive, and oxidative wear gives rise to dispersive and small oxide patches, adhered to sliding surfaces for TiSiN/TiAlN coatings with higher lambda of, for instance, 2.3:1. This tribolayer contributes to the lower wear volume loss than the case at room temperature for the TiSiN/TiAlN with a Lambda of 29 nm and a lambda of 2.3:1. In contrast, the TiSiN/TiAlN coating with a lower lambda of 1:2.3 exhibits mild abrasive and oxidative wear at 600 degrees C
A Creative Approach to Prepare a Macromolecular Flame Retardant with Flexibility: DOPO-Modified Epoxidized Polybutadiene
No full textThe incorporation of large loading of flame retardants generally causes embrittlement of materials. However, most of the rubbers and thermoplastic elastomers are flammable. Therefore, preparation of a flame retardant with potential toughening characteristics is urgently required for preparing materials with both good flame retardancy and toughness. The objective of the present work was to prepare a macromolecular flame retardant with good flexibility, that is, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-modified epoxidized polybutadiene (EPB-DOPO) via a creative approach of two-step reactions. First, polybutadiene (PB) was partially epoxidized to generate EPB; second, the reactive flame retardant DOPO reacted with epoxy groups to generate EPB-DOPO. EPB-DOPO with three epoxidation degrees was prepared: EPB5%-DOPO, EPB10%-DOPO, and EPB15%-DOPO. The chemical structure of EPB-DOPO was confirmed with proton nuclear magnetic resonance (H-1 NMR) and Fourier transform infrared (FTIR) spectra. Thermogravimetric analysis (TGA) showed that EPB-DOPO had good thermal stability. EPB10%-DOPO and EPB15%-DOPO passed the UL-94 V-2 and V-0 rating, respectively, and the gas-phase flame retardation mechanism was deduced. The glass transition temperature (T-g) of EPB-DOPO prepared in this study was below -20 degrees C. Due to little char formation, EPB10%-DOPO and EPB15%-DOPO showed good resilience even after flame ignition. This study has provided a creative strategy to prepare a macromolecular flame retardant with good flexibility
Highly flexible carbon nanotubes/aramid nanofibers composite papers with ordered and layered structures for efficient electromagnetic interference shielding
No full textEfficient electromagnetic interference (EMI) shielding materials with high flexibility, thin thickness, excellent mechanical property, and superior EMI shielding performance are urgently needed for modern electronic devices in areas of aerospace, military, and wireless communication systems. Herein, highly flexible multi-walled carbon nanotubes (MWCNTs)/aramid fibers (ANFs) composite papers with ordered and layered structures were successfully fabricated via a facile vacuum-assisted filtration. The obtained composite papers exhibited high electrical conductivity, outstanding mechanical property, excellent EMI shielding performance of 41.7 dB at a low density of 0.7-0.8 g cm(-3) and an average thickness of 0.3 mm. A parameter of the specific shielding effectiveness/thickness (SSE/t) was as high as 2395.8 dB cm(2) g(-1), which was benefited from the layer structures and the formation of conductive networks inside composite papers. It is expected to provide a promising strategy to prepare high-performance nanocomposite papers for EMI shielding in the field of artificial intelligence or smart and wearable electronics
Alginate/gelatin mineralized hydrogel modified by multilayers electrospun membrane of cellulose: Preparation, properties and in-vitro degradation
No full textSodium alginate (SA) hydrogel has a broad prospect in tissue engineering and other biomedical fields due to its biocompatibility. However, the single SA hydrogel has shown poor mechanical properties and cell adhesion, which seriously limited its application and development in tissue engineering scaffolds. Herein, the SA/gelatin (SAG) hydrogel was modified by the multilayers electrospinning membrane of cellulose (SAG-C). It showed excellent mechanical properties when the layer number of electrospinning membrane got to three. After mineralization (M-SAG-C), the mechanical and biocompatible properties have been further improved. The SAG, SAG-C, and M-SAG-C series hydrogels all had good water retention, swelling rates, and good degradation performance. The fluorescence staining and cell proliferation experiments showed that M-SAG, SAG-C, and M-SAG-C hydrogel materials had no apparent cytotoxicity. Simultaneously, the introduction of bone-like apatite in the M-SAG-C hydrogel material allowed the cells to have better adhesion and proliferation ability on the composite surface. And the higher the degree of mineralization, the better the cell compatibility of the hydrogel material. Therefore, such hydrogels had excellent biocompatibility and mechanical properties, which could be widely used in tissue engineering. (C) 2021 Elsevier Ltd. All rights reserved
Engineered bio-adhesive polyhedral oligomeric silsesquioxane hybrid nanoformulation of amphotericin B for prolonged therapy of fungal keratitis
No full textEven though fungal keratitis is a severe corneal disease that can lead to permanent vision loss, its therapeutic management is still problematic. This limitation is in part attributable to the fact that tear film renewal curtails exposure time of drug containing eye drops to the ocular surface. Accordingly, anti-microbial therapy needs to be performed repeatedly. Efforts to resolve this hindrance include developing formulations that prolong drug retention on the ocular surface which can in turn improve therapeutic efficacy as well as reduce administration frequency. To extend drug residence time on the ocular surface, we designed a novel organic-inorganic hybrid consisting of a PEG-PPG copolymer modified with polyhedral oligomeric silsesquioxane (POSS) groups. Its tailored POSS-micelles possess both good biocompatibility and bio-adhesiveness, which improve ocular delivery of poorly soluble drugs. We describe here use of mouse fungal keratitis model to determine the effects of this formulation encapsulating amphotericin B (AMB) on this condition. The results show that POSS-micelles significantly prolonged AMB retention time on the ocular surface, leading to improved resolution of this disease. Moreover, this treatment strategy had no toxic effects during ocular administration either in vitro or in vivo. Therefore, this POSS formulation bearing AMB has the potential to prolong drug retention time and improve its therapeutic efficacy in managing fungal keratitis
Superior and durable graphene-based composite coatings by bioinspired interfaces and alignment
No full textGraphene (G) has spectacular impermeability and chemical stability, holding promise as an excellent anticorrosion filler, and previous studies supports this hope. However, G only shows limited corrosion inhibition and even corrosion enhancement due to its inherent conductivity and uncontrolled distribution. Natural nacre provides an inspiration for constructing highly aligned structure coatings, in which G sheets are spatially isolated and keep 2D states. To realize the reliable and complete passivation, here we fabricate a nacre-like composite coating through functional G (aG) sheets and epoxy resin by interfaces and alignment designs. The relationship between alignment and properties as electrical conductivities, barrier properties, and impedance modulus is comprehensively compared and discussed. The parallel orientation of aG sheets not only increases the tortuosity to the diffusion paths of aggressive species but also reduces the electrical conductivity of coating in the direction to the electrons transfer, resulting in stability and durability of coating. Our work provides an insight on how to construct high-performance and durable G-based composite coatings by interfaces and structure designs in the future
Crosslinking of Active Polycarbosilane Initiated by Free Radical and Its Application in the Preparation of SiC Fibers
No full textIn the preparation of SiC ceramic fibers based on precursor polycarbosilane, the crosslinking treatment is a neccessary process to maintain the fiber morphology and improve the ceramic yield. In this study, polycarbosilane containing acrylate group (A-PCS) was used as raw material, and the thermal free radical initiator was introduced to realize the crosslinking formation during the pyrolysis process. FT-IR and DSC were used to analyze the influence of initiator content on crosslinking degree, crosslinking rate and thermal degradation rate of A-PCS; TG, elemental analysis and XRD were used to analyze the evolution of ceramic yield, composition and amorphous change with temperature. The introduction of free radical thermal initiator can improve the crosslinking rate of acrylate group in A-PCS and reduce the thermal weight loss at the crosslinking stage. When free radical thermal initiator (weight percent 1%) was added, the acrylate group was consumed completely after heating to 250 degrees C at 5 degrees C/min and the ceramic yield at 1500. was 69.5%. A-PCS fibers with diameter of 2-5 mu m were obtained by electrospinning process, and then transformed into SiC fibers by subsequent pyrolysis. The morphology of the SiC fibers was regular with no fusion phenomenon. In addition, with the increase of pyrolysis temperature, the amorphous SiC fiber can be transformed into crystalline structure
Analytical modelling of edge chipping in scratch of soda-lime glass considering strain-rate hardening effect
No full textSoda-Lime Glass (SLG) has been widely used in the creation of highly-functionalised optical devices. However, machining of SLG easily resulted in various defects. Among these defects, edge chipping (EC) can be treated as the most damageable in terms of both mechanical properties and optical performances. Although efforts have been paid to this topic, previous investigations (i) focused on edge chipping in low strain rate, which was 101-102 times lower than the ones in real machining, (ii) assumed edge chipping shape as circular, while the experiments in this work proved this assumption might be inaccurate in high strain rate circumstances, and (iii) were experimental efforts, resulting in limited knowledge of process principles. To fill this gap, this paper aims to propose an analytical model to calculate the size and the shape of edge chipping in scratch of soda-lime glass with the special consideration of strain-rate hardening effect. A series of experimental trials were performed to validate the model accuracy under different parameters. The details in scratching process were discussed by force analysis. A typical model application was given as well, which was designing the machining strategy based on the proposed model so that a required region with limited edge chipping can be obtained. Considering the research gaps mentioned above, the key findings in this paper are expected to be meaningful and helpful to provide references in the real fabrication of high-valued optical devices made of SLG