RESUMEN

A new compound, named coniferin B (1), and fourteen known compounds were purified and identified from the leaves and branches of Wikstroemia chamaedaphne Meisn. Their chemical structures were elucidated through analyzing spectroscopic and HRESIMS data. Compounds 2, 3, 5, 7-9, 11, and 13 were isolated from this plant for the first time. All compounds were assayed for cytotoxicity and activation of latent HIV activity on NH2 cells. The results showed that all compounds did not produce cytotoxicity at 10.0 µM and compounds 1, 9-11 showed weak activating activity with activation folds of 4.88, 7.14, 5.3, and 6.97, respectively.

Asunto(s)

RESUMEN

Herein, we report the preparation of porous polyimide (PI) with a cost-effective synthesis process by polycondensation between melamine and dianhydride monomers. The prepared porous PI served as a cathode for lithium-ion batteries (LIBs), and delivers a high discharge platform of 2.1 V and satisfactory electrochemical performance. Thus, the porous PI cathode provides another choice for LIBs.

RESUMEN

With the rapid development of smart campus, this paper studies the attitude tracking control of flexible manipulator (FM) in colleges and universities under elastic vibration and external disturbances. First, different from the traditional modeling based on ordinary differential equations (ODEs), the partial differential equations (PDEs) dynamic model of a manipulator system is established based on the Hamilton principle (HP). Second, the boundary control condition of the end system of the manipulator is introduced to adjust the vibration of the manipulator. Furthermore, a Proportional-Derivative (PD) boundary control (PDBC) strategy is proposed by the Lyapunov function to suppress the vibration of the manipulator. Finally, a numerical comparison simulation based on MATLAB/SIMULINK further verifies the robustness and anti-disturbance performance of the control method proposed in this paper.

RESUMEN

The maize/cassava relay intercropping system can be a specific and efficient cropping pattern in a tropical/subtropical field. Relay intercropping systems contribute to the optimization of land use, fostering sustainable and efficient agriculture. This study entails a first-year comparative intercropping experiment using maize (Zea mays L.) and cassava (Manihot esculenta Crantz). We determined the soil nutrient contents and physicochemical properties as well as the microbial communities by high-throughput sequencing. We found that the relay intercropping system changed the bacterial community structure, especially the rhizosphere microorganisms. The bacterial community was characterized by a higher abundance of the phyla Chloroflexi, Proteobacteria, and Actinobacteria and of the genus AD3, which are related to nutrient cycling and decreased bioavailability of Cd. At the same time, the relay intercropping system reduces the relative abundance of pathogenic bacteria and biomarkers of organic pollution. The relay intercropping systems significantly boosted soil pH and available K levels in addition to the monocropping yield. The results of this study suggest that maize/cassava relay intercropping, starting from the first year, not only provides a stable supply of food and income due to the diversified cropping systems but is also beneficial for the improvement of soil quality and the soil microbial community.

RESUMEN

BACKGROUND: The efficacy of vitamin C in sepsis remains controversial. Whether vitamin C can alleviate lipopolysaccharide (LPS)-induced myocardial injury by inhibiting pyroptosis has not been studied. This study aimed to evaluate the effects of vitamin C on LPS-induced myocardial injury in vitro. METHODS: H9C2 cells were treated with indicated concentrations of LPS, and the cell viability was then assessed by CCK-8 assay. The levels of lactate dehydrogenase (LDH), CK-MB, IL-18 and IL-1ß were examined by enzyme-linked immunosorbent assay (ELISA). The levels of intracellular reactive oxygen species (ROS) were measured using the fluorescent probe dichlorodihydrofluorescein diacetate (DCFH-DA). Western blot assays were conducted to determine the levels of the ROS-associated protein nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) and pyroptosis-associated proteins, such as NOD-like receptor (NLR) family pyrin domain containing 3 (NLRP3), caspase-1 and gasdermin D (GSDMD). The AKT inhibitor MK-2206 was then applied to explore the signalling pathway. Finally, H9C2 cells were divided into the control group, LPS group, vitamin C + LPS group, and N-acetyl-L-cysteine (NAC) + LPS group. The intracellular ROS, levels of associated proteins, cell viability, and release of LDH, CK-MB, IL-18 and IL-1ß were examined. RESULTS: LPS decreased cell viability and induced ROS and pyroptosis in H9C2 cells in a dose-dependent manner. Moreover, LPS activated the AKT/mTOR pathway in H9C2 cells. The AKT inhibitor MK-2206 protected H9C2 cells from LPS-induced death by suppressing pyroptosis, without changing intracellular ROS level. Vitamin C significantly inhibited intracellular ROS and cell pyroptosis in LPS-treated H9C2 cells. Moreover, vitamin C suppressed the activation of the AKT/mTOR pathway. CONCLUSIONS: Our data suggest that vitamin C alleviates LPS-induced myocardial injury by inhibiting pyroptosis via the ROS-AKT/mTOR signalling pathway and thus provide novel insights into the prevention of sepsis-induced myocardial dysfunction.

Asunto(s)

RESUMEN

The traditional synthesis of ammonia is an industrial process with high energy consumption that is not environmentally friendly; thus, it is urgent to develop cost-effective approaches to synthesize ammonia under ambient conditions. In recent years, the photochemical synthesis of ammonia has become a hot research frontier. In this mini review, we summarize the recent advances in materials sciences for photocatalytic nitrogen fixation. Beyond nitrogen fixation, we talk about an alternative for artificial ammonia synthesis and coupling reactions with other reactions for the synthesis of other high-value chemicals. The results and findings of this review will help the development of ammonia synthesis and the synthesis of other high-value chemicals.

RESUMEN

This paper devotes to the three-dimensional formation problem of multi-robots in obstacle environment. Given the desired formation pattern and the group trajectory, it is formulated as obtaining the control inputs of robots so that the formation errors converge to zero gradually with obstacle/collision avoidance subject to state and input constraints. The well-known nonlinear model predictive control (NMPC) can be utilized as the solution framework due to its stability and robustness according with the reference state vector. Particularly, the null-space-based modulated reference trajectory generator is proposed to modulate the reference state vector of each robot. The original reference velocity, obtained from the Lyapunov stability theory, will be modulated quantitatively in the presence of each obstacle, and then the modulated velocities are integrated effectively on the basis of null space. From the perspective of trajectory generator, it is proven that the robots will avoid obstacles or collision without violating the stability of formation system. Finally the simulation results demonstrate the high efficiency and strong robustness of our method.

RESUMEN

Previous studies have suggested that oxidative stress and autophagy results in acute kidney injury (AKI) during sepsis and microRNA (miR)­214 serves a vital role in the protection of kidneys subjected to oxidative stress. The present study aimed to test whether the renoprotection of miR­214 is related to autophagy in sepsis. The role of autophagy was investigated in a mouse model of cecal ligation and puncture (CLP). Reverse transcription­quantitative polymerase chain reaction (RT­qPCR) was used to analyze the expression of miR­214. The structure and function of kidneys harvested from the mice were evaluated. Kidney autophagy levels were detected with immunohistochemical, immunofluorescent and western blotting. It was found that miR­214 could alleviate AKI in septic mice by inhibiting the level of kidney autophagy. Furthermore, miR­214 inhibited autophagy by silencing PTEN expression in the kidney tissues of septic mice. These findings indicated that miR­214 ameliorated CLP­induced AKI by reducing oxidative stress and inhibiting autophagy through the regulation of the PTEN/AKT/mTOR pathway.

Asunto(s)

RESUMEN

The development of highly efficient photocatalysts is crucial for the remediation of organic pollutants. Herein, we reported a facile synthesis of oxygen vacancy rich Bi(OH)SO4·H2O photocatalyst by the control of precursor. The samples were characterized by XRD, scanning electron microscope, electron paramagnetic resonance, X-ray photoelectron spectroscopy etc. With more oxygen vacancies introduced, the photocatalytic activity on the degradation of RhB and tetracycline was significantly boosted. Density functional theory calculation was used to further reveal the influence of oxygen vacancy on the band structure of Bi(OH)SO4·H2O. The results and finding of this work are helpful for the development of sustainable environmental protection.

Asunto(s)

RESUMEN

Immobilized TiO2 nanoparticles modified by nanoscale CuS (CuS@TiO2NPs) were successfully synthesized and used as fibers for solid-phase microextraction (SPME) for the determination of some polycyclic aromatic hydrocarbons (PAHs) in water samples. A novel fiber has been developed by postprecipitation of CuS coated the titania nanoparticles in situ grown on a titanium wire annealed at 550 °C in a nitrogen ambient atmosphere. Its morphology and surface properties were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. It was connected to high performance liquid chromatography-ultraviolet detector (HPLC-UV) equipment by replacing the sample loop of a six-port injection valve, building the online SPME-HPLC-UV system. Variables affecting extraction procedures, including desorption time, stirring speed, extraction temperature, extraction time and ionic strength were investigated and the parameters were optimized. The SPME fiber exhibits high selectivity for the five PAHs studied. The linear ranges varied between 0.15 µg L-1 and 200 µg L-1 with correlation coefficients ranging from 0.9913 to 0.9985. LODs and LOQs ranged from 0.02-0.04 µg L-1 and 0.07-0.13 µg L-1. RSDs for one fiber and fiber-to-fiber were in the range of 3.2-4.3% and 4.6-6.8%, respectively. Additionally, the fiber possessed advantages such as resistance to organic solvent, high mechanical strength and difficult breakage, making it have strong potential applications in the selective extraction of PAHs from complex water samples at trace levels.

RESUMEN

In this work, a polypyrrole (PPy)/TiO2 nanocomposite coating was fabricated by the direct electropolymerization of pyrrole on annealed TiO2 nanoparticles and evaluated as a novel direct immersion solid phase microextraction (DI-SPME) fiber coating for extraction of trace amounts of pollutants in environmental water samples. The functionalized fiber is mechanically and chemically stable, and can be easily prepared in a highly reproducible manner. The effects of the pyrrole monomer concentration, polymerization voltage and polymerization time on the fiber were discussed. Surface morphological and compositional analyses revealed that the composite coating of nano polypyrrole and titanium dioxide nanoparticles (TiO2NPs) uniformly doped the Ti substrate. The as-fabricated fiber exhibited good extraction capability for phenolic compounds in combination with high performance liquid chromatography-UV detection (HPLC-UV). At the optimum SPME conditions, the calibration curves were linear (R 2 ≥ 0.9965). LODs and LOQs of less than 0.026 µg L-1 and 0.09 µg L-1 , respectively, were achieved, and RSDs were in the range 3.5-7.2%. The results obtained in this work suggest that PPy/TiO2 is a promising coating material for future applications of SPME and related sample preparation techniques.

RESUMEN

Vitamin D deficiency is associated with acute myocardial infarction (AMI); thus we aimed to explore improvement effects of 1,25-dihydroxyvitamin D3 (VD3) on the AMI and its potential mechanism. AMI models were constructed using male C57/BL6J mice and randomly treated with normal saline or VD3, using sham rats as control. Heart functions, myocardial damage, apoptosis, and inflammation were evaluated. Cardiomyocytes isolated from 3-day-old suckling mice were used for in vitro verification. After VD3 treatment, AMI-induced cardiac dysfunction was reversed with better cardiac function parameters. VD3 treatment reduced inflammatory cell infiltration and myocardial infarction area accompanied by the reduction of inflammatory factors and myocardial infarction markers compared with the AMI group. VD3 treatment obviously alleviated AMI-induced myocardial apoptosis, along with Bcl-2 upregulation and downregulation of caspase-3, caspase-9, and Bax. Both in vivo and in vitro experiments revealed that VD3 enhanced the expression of LC3II and Beclin-1 and decreased soluble p62. Furthermore, VD3 enhanced the AMI-caused inhibition of PI3K, p-AKT, and p-mTOR expression, which was conversely reversed by the addition of 3-methyladenine in vitro. The study highlights the improvement effects of VD3 on cardiac functions. We proposed a potential mechanism that VD3 protects against myocardial damage, inflammation, and apoptosis by promoting autophagy through PI3K/AKT/mTOR pathway.

Asunto(s)

RESUMEN

Aims. More than half of the patients with sepsis would develop cardiac dysfunction, which is termed as sepsis-induced myocardial dysfunction (SIMD). Previous studies suggest that autophagy may play an important role in SIMD. The present study investigated whether miR-214-3p could attenuate SIMD by inhibiting autophagy. Main Methods. In this article, we investigated the role of autophagy in a mouse model of cecal ligation and puncture (CLP). The structure and function of hearts harvested from the mice were evaluated. Myocardial autophagy levels were detected with immunohistochemical, immunofluorescent, and Western blot. Key Findings. miR-214-3p can alleviate SIMD in septic mice by inhibiting the level of cardiac autophagy to attenuate myocardial dysfunction. Moreover, this study showed that miR-214-3p inhibited autophagy by silencing PTEN expression in the myocardial tissues of septic mice. Significance. This study showed that miR-214-3p attenuated SIMD through myocardial autophagy inhibition by silencing PTEN expression and activating the AKT/mTOR pathway. The present findings supported that miR-214-3p may be a potential therapeutic target for SIMD.

Asunto(s)

RESUMEN

A novel solid phase microextraction fiber of polyaniline coated titania composite nanotube (PANI@TiO2NTs/Ti) array was fabricated on a titanium wire by in situ oxidation. The effects of the inorganic acid medium, aniline concentration, and oxidation voltage on the electropolymerization of aniline were discussed. The best forming conditions for the composite fiber obtained by analyzing the surface morphology and composition of the fibers were as follows:electrolyte composing, 0.5 mol/L aniline-1 mol/L H2SO4; electropolymerization, 10 V for 60 min. The developed fibers were used in conjunction with high performance liquid chromatography for the extraction and determination of ultraviolet filters in samples, and the extraction conditions optimized were as follows:extraction time 40 min, desorption time 4 min, extraction temperature 40℃, stirring rate 600 r/min. The average recoveries of the target analytes spiked in real samples ranged from 78.2% to 118%, and the relative standard deviations ranged from 4.4% to 8.9%. The developed method is simple, rapid, and accurate, and it is suitable for the sensitive determination of UV filters in environmental water samples.

RESUMEN

It is a huge challenge to achieve highly efficient fire retardance with no mechanical damage to polymers. In our current research, a novel core-shell titanium dioxide@diphenylphosphinic (TiO2@DPP) nanosphere was first synthesized through a hydrothermal reacting process, and applied in simultaneously enhancing the fire retardance and mechanical properties of polycarbonate (PC). The well-designed TiO2@DPP exhibited a significant effect on combustion performance and mechanical reinforcement of PC. At only 0.10 wt % of TiO2@DPP, PC/TiO2@DPP passed the UL-94 V-0 rating, and its oxygen index value rose to 29.3%. Moreover, the peak value of the heat release rate was remarkably decreased by 34.1% in the combustion test, accompanied by the formation of more compacted char layer and the release of more incombustible gas. Equally important another aspect is that the PC containing only 0.10 wt % of TiO2@DPP possessed higher elongation at break and higher tensile strength than pure PC, correspondingly increased by 27.7 and 14.7%. The analysis of the flame-retardant mechanism revealed that the improved fire retardance of PC is primarily ascribed to the barrier action of a cross-linking network containing phosphorus and titanium, the dilution of nonflammable gases such as H2O, and the quenching effect of free radicals which are from the phosphorous group in the gas phase. All these experimental results demonstrate that the core-shell hybrid TiO2@DPP may achieve a simultaneous significant improvement in fire retardance and mechanical properties of PC.

RESUMEN

Bi2WO6@TCNQ visible light photocatalyst with a core-shell structure was synthesized by adsorption methods. The core-shell structure results in the fast transfer of photogenerated carriers, reduced carrier recombination and photogenerated holes on the HOMO level of TCNQ can be injected into the VB of Bi2WO6 under visible light irradiation, resulting in the direct oxidation of organic pollutants. The photocatalytic activity of Bi2WO6@TCNQ was gradually enhanced with an increasing proportion of TCNQ. When the mass fraction of TCNQ reaches 0.5%, it exhibits the highest visible light activity. The apparent rate constant k of Bi2WO6@TCNQ-0.5% is almost 2.2 times as high as that of pure Bi2WO6.

RESUMEN

We present in this paper the convergence properties of Jacobi spectral collocation method when used to approximate the solution of multidimensional nonlinear Volterra integral equation. The solution is sufficiently smooth while the source function and the kernel function are smooth. We choose the Jacobi-Gauss points associated with the multidimensional Jacobi weight function [Formula: see text] (d denotes the space dimensions) as the collocation points. The error analysis in [Formula: see text]-norm and [Formula: see text]-norm theoretically justifies the exponential convergence of spectral collocation method in multidimensional space. We give two numerical examples in order to illustrate the validity of the proposed Jacobi spectral collocation method.