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•Graphene-ZnO composite was facilely fabricated by a spontaneous reduction.•ZnO enhanced the the sensitivity of electrochemical biosensor.•Simultaneous electrochemical detection of ...AA, UA and DA.•Good reproducibility and stability.
Reduced graphene oxide-zinc oxide (RGO–ZnO) composite was facilely fabricated by a spontaneous reduction of graphene oxide via zinc slice in one-pot approach at room temperature, and used to modify glassy carbon electrode (GCE) for developing of electrochemical biosensor (RGO–ZnO/GCE). The as-prepared RGO–ZnO was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and transmission electron microscope (TEM). It was revealed that the existence of ZnO in RGO–ZnO/GCE largely enhanced the electroactive surface area (EASA) and therefore the sensitivity for electrochemical sensing. In the mixtures of ascorbic acid (AA), dopamine (DA) and uric acid (UA), the biosensor exhibited three well-resolved voltammetric peaks (ΔEAA–DA=236mV, ΔEDA–UA=132mV, ΔEAA–UA=368mV) in the differential pulse voltammetry (DPV) measurements, allowing a simultaneous electrochemical detection of these biomolecules. The liner relationships between current intensities and concentrations were found to be 50–2350μM, 1–70μM and 3–330μM, with detection limits of 3.71μM, 0.33μM and 1.08μM for AA, UA and DA, respectively. The as-prepared RGO–ZnO/GCE biosensor displayed a good reproducibility and stability and was applied for detection of of AA, DA and UA in real plasma and urine samples with satisfying results.
In this article, a wideband <inline-formula> <tex-math notation="LaTeX">2\times 2 </tex-math></inline-formula> filtering antenna array is proposed and studied for fixed beam applications. The device ...is composed of a patch antenna array, and a slotline-based four-way filtering power divider has served as the feeding network. The integration of the antenna and the feeding parts is not a simple combination but a cosynthesis, where the characters of the two parts are both involved during the integration. First, the presented network is analyzed through an equivalent-circuit study to verify the frequency selectivity. Subsequently, integration synthesis of the network and the patch array is carried out to realize the filtering antenna array. For demonstration purposes, a filtering antenna array centered at 3 GHz is developed and fabricated. The measured absolute impedance bandwidth is 1.13 GHz, corresponding to a fractional bandwidth of 37.1%, and out-of-band rejection of up to 9.5 GHz is achieved. Compared with the array fed by a traditionally T-junction-based power divider, the absolute impedance bandwidth of the filtering array is significantly increased by 47%. The in-band gain of the proposed array is higher than 9.7 dBi, which is over 12.1 dBi from 2.75 to 3.25 GHz. The results denote that compared with the previously reported literature, the proposed filtering antenna array features sharp cutoff response, wide impedance bandwidth, high gain, and low cross-polarization level, with the harmonic suppression of up to three times the center frequency.
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
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.
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.
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.
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.
Chiral aliphatic amine and alcohol derivatives are ubiquitous in pharmaceuticals, pesticides, natural products and fine chemicals, yet difficult to access due to the challenge to differentiate ...between the spatially and electronically similar alkyl groups. Herein, we report a nickel-catalyzed enantioselective hydroalkylation of acyl enamines and enol esters with alkyl halides to afford enantioenriched α-branched aliphatic acyl amines and esters in good yields with excellent levels of enantioselectivity. The operationally simple protocol provides a straightforward access to chiral secondary alkyl-substituted amine and secondary alkyl-substituted alcohol derivatives from simple starting materials with great functional group tolerance.
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