To study the effects of graphene oxide (GO) dimension on the mechanical and dielectric performance of epoxy resin (EP), two kinds of GO with different dimensions were selected and characterized by ...Fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The results showed that the two kinds of GO had similar chemical structure, but different average particle sizes of 190.1 nm (SGO) and 1510 nm (MGO), respectively. The mechanical properties, dynamic mechanical properties, and dielectric properties of the EP/GO composites are analyzed using electronic universal testing machine, Rockwell hardness tester, dynamic mechanical analysis (DMA) and broadband dielectric impedance relaxation spectrometer. Results revealed that the GO dimension plays important role in determining the dispersion of the filler in EP matrix, and further determines the mechanical properties and dielectric performance of the composites. EP/SGO with better dispersion of GO in the EP matrix exhibits better mechanical properties, higher glass transition temperature, higher dielectric constant. Related mechanism has been proposed.
The 2019 positive Indian Ocean Dipole (IOD) was the strongest event since the 1960s which developed independently without coinciding El Niño. The dynamics is not fully understood. Here we show that ...in March–May, westward propagating oceanic Rossby waves, a remnant consequence of the weak 2018 Pacific warm condition, led to anomalous sea surface temperature warming in the southwest tropical Indian Ocean (TIO), inducing deep convection and anomalous easterly winds along the equator, which triggered the initial cooling in the east. In June–August, the easterly wind anomalies continued to evolve through ocean‐atmosphere coupling involving Bjerknes feedback and equatorial nonlinear ocean advection, until its maturity in September–November. This study clarifies the contribution of oceanic Rossby waves in the south TIO in different dynamic settings and reveals a new triggering mechanism for extreme IOD events that will help to understand IOD diversity.
Plain Language Summary
The Indian Ocean Dipole (IOD) is an ocean‐atmosphere coupled climatic phenomenon which can cause severe social and economic losses in the surrounding regions such as drought in the Maritime Continent/Australia and flooding in East Africa. The IOD features a see‐saw structure accompanied by an anomalous sea surface temperature gradient, winds, and oceanic adjustments. The El Niño–Southern Oscillation in the Pacific is an important trigger to a strong IOD event. However, an extreme positive IOD event occurred in 2019 without a concurrent or ensuing El Niño. We show that the thermocline warming associated with anomalous ocean downwelling in the southwest tropical Indian Ocean triggered atmospheric convection, inducing anomalous easterly winds along the equator and hence, positive feedbacks associated with an IOD event. This study may help to understand the evolution of extreme IOD and improve IOD predictability.
Key Points
The oceanic downwelling Rossby waves in the south tropical Indian Ocean is key to the 2019 extreme positive Indian Ocean Dipole (IOD)
The Rossby waves induced thermocline warming, triggering wind‐evaporation‐SST feedback thus anomalous easterly winds along the equator
The easterly wind anomalies further triggered the Bjerknes feedback and other positive feedbacks and established an extreme IOD
Enzymatic electrosynthesis has gained more and more interest as an emerging green synthesis platform, particularly for the fixation of CO2. However, the simultaneous utilization of CO2 and a ...nitrogenous molecule for the enzymatic electrosynthesis of value‐added products has never been reported. In this study, we constructed an in vitro multienzymatic cascade based on the reductive glycine pathway and demonstrated an enzymatic electrocatalytic system that allowed the simultaneous conversion of CO2 and NH3 as the sole carbon and nitrogen sources to synthesize glycine. Through effective coupling and the optimization of electrochemical cofactor regeneration and the multienzymatic cascade reaction, 0.81 mM glycine was yielded with a highest reaction rate of 8.69 mg L−1 h−1 and faradaic efficiency of 96.8 %. These results imply a promising alternative for enzymatic CO2 electroreduction and expand its products to nitrogenous chemicals.
An enzymatic electrocatalytic system was developed for the simultaneous conversion of CO2 and NH3 for glycine synthesis. This system was inspired by the reductive glycine pathway in vivo and involves an in vitro multienzymatic cascade reaction. It shows the potential of enzymatic CO2 electroreduction for the synthesis of nitrogenous value‐added chemicals.
Although global erasure of DNA methylation has been observed in zygotes and primordial germ cells, the responsible enzyme(s) have been elusive. The demonstration that members of the Tet (ten eleven ...translocation) family of proteins are capable of catalyzing conversion of 5-methylcytosine (5mC) of DNA to 5-hydroxymethylcytosine (5hmC) raises the possibility that Tet proteins may participate in this process. Indeed, recent studies have implicated the involvement of Tet3 in the conversion of 5mC to 5hmC in zygotes. This result, combined with the demonstration that Tet proteins can further oxidize 5hmC to 5-carboxylcytosine followed by excision by thymine-DNA glycosylase, raises the possibility that active demethylation may take place in a process that involves Tet3-mediated oxidation followed by base excision repair. We demonstrated by immunostaining of mitotic chromosome spreads of preimplantation embryos that the 5hmC associated with the paternal genome in zygotes is gradually lost during preimplantation development. Our study suggests that, although the conversion of 5mC to 5hmC in zygotes is an enzyme-catalyzed process, loss of 5hmC during preimplantation appears to be a DNA replication-dependent passive process.
DOT1 (disruptor of telomeric silencing; also called Kmt4) was initially discovered in budding yeast in a genetic screen for genes whose deletion confers defects in telomeric silencing. Since the ...discovery ∼10 years ago that Dot1 and its mammalian homolog, DOT1L (DOT1-Like), possess histone methyltransferase activity toward histone H3 Lys 79, great progress has been made in characterizing their enzymatic activities and the role of Dot1/DOT1L-mediated H3K79 methylation in transcriptional regulation, cell cycle regulation, and the DNA damage response. In addition, gene disruption in mice has revealed that mouse DOT1L plays an essential role in embryonic development, hematopoiesis, cardiac function, and the development of leukemia. The involvement of DOT1L enzymatic activity in leukemogenesis driven by a subset of MLL (mixed-lineage leukemia) fusion proteins raises the possibility of targeting DOT1L for therapeutic intervention.
Abstract
Background
The triglyceride-glucose index (TyG index) has been regarded as a reliable alternative marker of insulin resistance and an independent predictor of cardiovascular outcomes. ...Whether the TyG index predicts adverse cardiovascular events in patients with diabetes and acute coronary syndrome (ACS) remains uncertain. The aim of this study was to investigate the prognostic value of the TyG index in patients with diabetes and ACS.
Methods
A total of 2531 consecutive patients with diabetes who underwent coronary angiography for ACS were enrolled in this study. Patients were divided into tertiles according to their TyG index. The primary outcomes included the occurrence of major adverse cardiovascular events (MACEs), defined as all-cause death, non-fatal myocardial infarction and non-fatal stroke. The TyG index was calculated as the ln (fasting triglyceride level mg/dL × fasting glucose level mg/dL/2).
Results
The incidence of MACE increased with TyG index tertiles at a 3-year follow-up. The Kaplan–Meier curves showed significant differences in event-free survival rates among TyG index tertiles (P = 0.005). Multivariate Cox hazards regression analysis revealed that the TyG index was an independent predictor of MACE (95% CI 1.201–1.746; P < 0.001). The optimal TyG index cut-off for predicting MACE was 9.323 (sensitivity 46.0%; specificity 63.6%; area under the curve 0.560; P = 0.001). Furthermore, adding the TyG index to the prognostic model for MACE improved the C-statistic value (P = 0.010), the integrated discrimination improvement value (P = 0.001) and the net reclassification improvement value (P = 0.019).
Conclusions
The TyG index predicts future MACE in patients with diabetes and ACS independently of known cardiovascular risk factors, suggesting that the TyG index may be a useful marker for risk stratification and prognosis in patients with diabetes and ACS.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
High-performance thermally insulating materials is highly desirable for many applications in which heat transfer should be strictly restricted. Traditional organic or inorganic insulation materials ...are limited by either poor thermal stability or mechanical brittleness. Here, SiO2 nanoparticles crosslinked polyimide aerogels synthesized by one-pot freeze-drying are presented, which show excellent mechanical properties and super-insulating behavior in a wide temperature range. The highly porous structure of the aerogel and nanosized components benefit the significant reduction of thermal conductivity through inhibiting gas conduction and imparting interfacial thermal resistance, respectively. The PI/SiO2 composite aerogel with a density of 0.07 mg cm−3 can achieve a low thermal conductivity of 21.8 mW m−1 K−1, which is lower than the most common super-insulating criterion (25 mW m−1 K−1). More importantly, the PI/SiO2 aerogel exhibits good thermal insulation performance at elevated temperatures, with a thermal conductivity still lower than 35 mW m−1 K−1 even at 300 °C. Therefore, the mechanically strong and super-insulating PI/SiO2 composite aerogels are promising candidates for practical thermal insulation applications.
Silica nanoparticle crosslinked polyimide aerogels exhibit super-thermal insulation performance with a low thermal conductivity of 21.8 mW m−1 K−1 at room temperature and 33.2 mW m−1 K−1 at 300 °C. Display omitted
Ether based electrolytes have surfaced as alternatives to conventional carbonates allowing for enhanced electrochemical performance of sodium-ion batteries; however, the primary source of the ...improvement remains poorly understood. Here we show that coupling titanium dioxide and other anode materials with diglyme does enable higher efficiency and reversible capacity than those for the combination involving ester electrolytes. Importantly, the electrolyte dependent performance is revealed to be the result of the different structural evolution induced by a varied sodiation depth. A suit of characterizations show that the energy barrier to charge transfer at the interface between electrolyte and electrode is the factor that dominates the interfacial electrochemical characteristics and therefore the energy storage properties. Our study proposes a reliable parameter to assess the intricate sodiation dynamics in sodium-ion batteries and could guide the design of aprotic electrolytes for next generation rechargeable batteries.
Abstract
Resistance change under mechanical stimuli arouses mass operational heat, damaging the performance, lifetime, and reliability of stretchable electronic devices, therefore rapid thermal heat ...dissipating is necessary. Here we report a stretchable strain sensor with outstanding thermal management. Besides a high stretchability and sensitivity testified by human motion monitoring, as well as long-term durability, an enhanced thermal conductivity from the casted thermoplastic polyurethane-boron nitride nanosheets layer helps rapid heat transmission to the environments, while the porous electrospun fibrous thermoplastic polyurethane membrane leads to thermal insulation. A 32% drop of the real time saturated temperature is achieved. For the first time we in-situ investigated the dynamic operational temperature fluctuation of stretchable electronics under repeating stretching-releasing processes. Finally, cytotoxicity test confirms that the nanofillers are tightly restricted in the nanocomposites, making it harmless to human health. All the results prove it an excellent candidate for the next-generation of wearable devices.
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