Oxide Chains Research Articles

Structure-property relationship of reversible magnetic chirality tuning

The Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction mediates collinear magnetic interactions via the conduction electrons of a nonmagnetic spacer, resulting in a ferro- or antiferromagnetic magnetization in magnetic multilayers. Recently it has been discovered that heavy nonmagnetic spacers are able to mediate an indirect magnetic coupling that is noncollinear and chiral. This Dzyaloshinskii-Moriya-enhanced RKKY interaction causes the emergence of a variety of interesting magnetic structures, such as skyrmions and spin spirals. Here, we show by spin-polarized scanning tunneling microscopy that the interchain coupling between manganese oxide chains on Ir(001) can reproducibly be switched from chiral to collinear antiferromagnetic by increasing the oxidation state of ${\mathrm{MnO}}_{2}$, while the reverse process can be induced by thermal reduction. The underlying structure--property relationship is revealed by low-energy electron diffraction intensity analysis. Density functional theory calculations suggest that the magnetic transition may be caused by a significant increase of the Heisenberg exchange which overrides the Dzyaloshinskii-Moriya interaction upon oxidation.

Intermittent Fasting Activates AMP-Kinase to Restructure Right Ventricular Lipid Metabolism and Microtubules

Intermittent fasting (IF) extends life span via pleotropic mechanisms, but one important molecular mediator is adenosine monophosphate-activated protein kinase (AMPK). AMPK enhances lipid metabolism and modulates microtubule dynamics. Dysregulation of these molecular pathways causes right ventricular (RV) failure in patients with pulmonary arterial hypertension. In rodent pulmonary arterial hypertension, IF activates RV AMPK, which restores mitochondrial and peroxisomal morphology and restructures mitochondrial and peroxisomal lipid metabolism protein regulation. In addition, IF increases electron transport chain protein abundance and activity in the right ventricle. Echocardiographic and hemodynamic measures of RV function are positively associated with fatty acid oxidation and electron transport chain protein levels. IF also combats heightened microtubule density, which normalizes transverse tubule structure.

Structural and Molecular Basis for Mitochondrial DNA Replication and Transcription in Health and Antiviral Drug Toxicity.

Human mitochondrial DNA (mtDNA) is a 16.9 kbp double-stranded, circular DNA, encoding subunits of the oxidative phosphorylation electron transfer chain and essential RNAs for mitochondrial protein translation. The minimal human mtDNA replisome is composed of the DNA helicase Twinkle, DNA polymerase γ, and mitochondrial single-stranded DNA-binding protein. While the mitochondrial RNA transcription is carried out by mitochondrial RNA polymerase, mitochondrial transcription factors TFAM and TFB2M, and a transcription elongation factor, TEFM, both RNA transcriptions, and DNA replication machineries are intertwined and control mtDNA copy numbers, cellular energy supplies, and cellular metabolism. In this review, we discuss the mechanisms governing these main pathways and the mtDNA diseases that arise from mutations in transcription and replication machineries from a structural point of view. We also address the adverse effect of antiviral drugs mediated by mitochondrial DNA and RNA polymerases as well as possible structural approaches to develop nucleoside reverse transcriptase inhibitor and ribonucleosides analogs with reduced toxicity.

Rock–Fluid Interactions of Alkyl Ether Carboxylate Surfactants with Carbonates: Wettability Alteration, ζ-Potential, and Adsorption

This work evaluated the rock–fluid interactions of two linear alkyl ether carboxylate (AEC) surfactants C11E11A and C12E7A in carbonates: wetting ability, ζ-potential, and adsorption capacity. Contact angle measurements showed that the ability of AECs to hydrophilize the surface is strongly affected by the ethylene oxide (EO) chain length and the presence of electrolytes. An AEC with a shorter EO chain C12E7A demonstrated a better wetting ability and decreased the contact angle value on the limestone surface from 113 to 27 ± 11° in deionized (DI) water and until 17 ± 5° in 5 wt % NaCl. The mechanism of surfactant action was assessed through thermodesorbed hydrocarbon analysis and organic matter characterization with the help of the Rock-Eval (RE) pyrolysis technique for the first time. The analysis results revealed that all surfactant compositions partially removed free oil and heavy oil components from limestone samples. Also, the presence of C12E7A molecules was detected in the samples after surfactant treatment that indicates that a better wetting ability is achieved by the combination of washing hydrocarbons and adsorption of surfactants on clean sites. The combination of ζ-potential measurements and static adsorption test on crushed limestone demonstrated that the adsorption of AECs in deionized water is not governed by electrostatic interactions and mainly occurs due to hydrogen bonding. Salinity has a significant effect on the adsorption behavior of AECs and leads to the partial destruction of hydrogen bonds and the shift from monomolecular adsorption in DI water to polymolecular adsorption in brines. The adsorption of C11E11A achieved ∼9 mg/g-rock and was higher than that of C12E7A, showing a maximum value of ∼4 mg/g-rock. This work provides a set of experiments that characterize the behavior of AECs during interactions with carbonate rock and describes a novel approach of the wettability shift mechanism assessment through RE pyrolysis.

Phenylenediamine‐phenyl phosphonic acid salts toward good flame retardancy and smoke suppression epoxy resin

AbstractAn environmentally friendly flame retardant named PO‐PA was designed to enhance the flame retardancy of epoxy resin (EP). Following the principles of efficiency and simplicity, PO‐PA was synthesized through a one‐pot reaction between phenyl phosphonic acid and p‐phenylenediamine. The chemical structure of PO‐PA was characterized by Fourier‐transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), elemental analysis (EA) and thermogravimetric analysis (TGA). EP containing 10 wt% PO‐PA (EP/10%PO‐PA) passed the UL94 V‐0 rating without dripping. In the cone calorimeter test, the total heat release and total smoke production of EP/10%PO‐PA decreased by 44% and 65%, respectively. TG‐FTIR and Py‐GC/MS were used to investigate the pyrolysis gases of the EP composites and PO‐PA, respectively. Scanning electron microscopy (SEM), FTIR, EA and XPS were utilized to study the char residues. It was proved that PO‐PA notably promoted the formation of smooth protective char layer in the condensed phase and effectively inhibited the oxidation chain reactions through releasing the phosphorus‐containing radicals in gas phase, which was not mentioned in the similar research based on phenyl phosphonic acid.

Constant oxidation of atrazine in Fe(III)/PDS system by enhancing Fe(III)/Fe(II) cycle with quinones: Reaction mechanism, degradation pathway and DFT calculation

Quinones are potential pollutants and redox active compounds widely distributed in environmental media. In this study, methyl-p-benzoquinone (MBQ) was introduced into Fe(III)/peroxydisulfate system (Fe(III)/PDS) to expedite the conversion of Fe(III) to Fe(II) and the degradation of atrazine (ATZ), ultimately establishing an environmentally friendly system of “treating pollution with pollution”. MBQ/Fe(III)/PDS system showed superior performance to traditional Fe(II)/PDS system in pH range of 2–7. Sulfate radical (SO4•−) and hydroxyl radical (•OH) were confirmed to exist in MBQ/Fe(III)/PDS system according to alcohol quenching experiments and ESR tests. Meanwhile, stable 80% of η[PMSO2] (i.e., the molar ratio of PMSO2 generation to PMSO consumption) was achieved and manifested that highly reactive substance Fe(IV) also participated in MBQ/Fe(III)/PDS system. The spontaneous transformation of MBQ and methyl-hydroquinone (MHQ) drove Fe(III)/Fe(II) cycle, during which MHQ induced Fe(III) reduction and Fe(II) regeneration. Transformation pathways of ATZ were proposed based on HPLC-MS detection and DFT calculation and ATZ degradation could be initiated by lateral chain oxidation and dechlorination-hydroxylation. The acute toxicity, bioaccumulation factor, developmental toxicity and mutagenicity of ATZ and its degradation intermediates were evaluated by Toxicity Estimation Software Tool, and the luminescent bacteria test was conducted to investigate the acute toxicity variation of the reaction solution. Cl− obviously inhibited ATZ degradation and three main by-products generation, while humic acid (HA) had little effect on them probably due to the established balance between inhibition (some components in HA competed to consume reactive species) and acceleration (quinone units in HA also facilitated Fe(III)/Fe(II) cycle).

Study of the Effects of Various Polyphenols on Proliferative Processes and the Functional State of Liver Mitochondria of Experimental Toxic Hepatitis

Background: Toxic hepatitis is considered one of the most serious concern of health care. Because, would be reason for developing liver cirrhosis and primary liver cancer. Materials and Methods: In this work, models of toxic hepatitis animals prepared and effects of various polyphenols on the liver mitochondria of the model animals were studied. For this, liver mitochondria of the animals were isolated and the lipid peroxidation, the respiration rate and parameters of oxidative phosphorylation, activity of enzymes of the respiratory chain, and mitochondrial proteins synthesis were determined. Results: It was defined that studied polyphenols of plant origin, which are rutan and hetasan showed antioxidative properties. It was shown that these polyphenols express stabilization influence on decreased functional conditions of liver mitochondria in the case of toxic hepatitis by stimulating energy-producing function, activity of oxidative chain enzymes and mitochondria proteins synthesis. During the investigations of polyphenols’ antiproliferative abilities, it was defined that rutan is characterized by considerable antifibrotic activity. Conclusion: The plant polyphenols rutan and hetasan are hepatoprotectors with pronounced therapeutic effects in toxic hepatitis. In this study, it was determined that the therapeutic effect of these polyphenols includes an improvement of energy metabolism, a decrease of the process of lipid peroxidation of mitochondrial membranes, as well as the proliferation of fibrous tissue in the liver parenchyma. It may be occurs do to antioxidant activity of the polyphenols.

Neurotoxicity of mycotoxin citrinin: Novel evidence in developing zebrafish and underlying mechanisms in human neuron cells.

Citrinin (CTN) is a mycotoxin that is found as a contaminant in various types of food/feed grains and fermented food supplements. Previous studies have already established the nephrotoxicity and hepatotoxicity of CTN, but the neurotoxicity of CTN has not been clearly examined. In this study, CTN at 2-20μM was first found to interfere with the neural ganglia formation and locomotive behavior of embryonic zebrafish, a vertebrate animal model, at 24 hpf and 6 dpf, respectively. Further exposure of human neuroblastoma SH-SY5Y cells to 10 and 20μM CTN for 72h indicated that pathways responsible for neuron differentiation and projection guidance were down-regulated while oxidative stress and electron transport chain pathways were up-regulated based on the enrichment results of GSEA in the transcriptomic profiling. PCR analysis verified that CTN significantly down-regulated the expression of marker genes involved in neuron differentiation and synaptic signaling. CTN at the doses impairing cellular neurite outgrowth did not trigger mitochondrial oxidative stress and dysfunction. The neurotoxic mechanisms of CTN provide new information that is valuable in the assessment of CTN-related health risk for the general public.

HRMAS-NMR and simulation study of the self-assembly of surfactants on carbon nanotubes.

Polyethoxylated surfactants, such as those of the Tween and Pluronic series, are commonly used to disperse carbon nanotubes (CNTs) and other nanoparticles. However, the current understanding of the nature of interactions between these surfactants and CNTs is limited. The nature of the interactions between surfactants (Tween-80 [T80] and Pluronic F68 [PF68]) and CNTs was investigated using high-resolution magic angle spinning nuclear magnetic resonance (HRMAS-NMR) and coarse-grained molecular dynamics (MD) simulations. HRMAS-NMR revealed that T80 molecules interact with single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) via the oleyl chain, whereas PF68 molecules interact with the surface of SWCNTs and MWCNTs via the polypropylene oxide residues. The polyethylene oxide chains were oriented towards the external aqueous environment. The HRMAS-NMR results were supported by MD simulations, and the latter provided further insights into the nature of the interactions.

Supramolecular nanostructures of coil-rod-coil molecules containing a 9,10-distyrylanthracene group in aqueous solution and their optical properties of assemblies.

A series of coil-rod-coil molecules containing a 9,10-distyrylanthracene (DSA) core was successfully synthesized. The flexible parts of these molecules are composed of different polyethylene oxide chains. These molecules with aggregation-induced luminescence properties can be assembled into micelles, spheres, and sheet-like nano-assemblies in aqueous solution and have a strong ability to form charge-transfer complexes with the electron-deficient small molecules 2,4,5,7-tetranitro-9-fluorenone and 2,4,6-trinitrophenol. Interestingly, under ultraviolet light irradiation, the DSA structure undergoes photolysis and induces the disappearance of the aggregation-induced luminescence phenomena, giving these molecules application potential as a photodegradable material. In addition, these molecules are suitable organic dyes for information encryption and anti-counterfeiting applications.

Distinct effects of zwitterionic molecules on ionic solvation in (ethylene oxide)10: a molecular dynamics simulation study.

Ion-containing polymers play a critical role in various energy and sensing applications. Adjusting ionic solvation is one approach to tune the performance of ion-containing polymers. Small zwitterionic molecule additives have presented their ability to regulate ionic solvation because they possess two charged groups covalently connected together. One remaining question is how the effect of zwitterionic molecules on ionic solvation depends on their own chemical structures, especially the anionic groups. To shed light on this question, we investigate the ionic solvation structure and dynamics in LiTFSI/(ethylene oxide)10 (EO10) with the presence of three distinct zwitterionic molecules (MPC, SB, and CB) using molecular dynamics simulations (MPC: 2-methacryloyloxyethyl phosphorylcholine, SB: sulfobetaine ethylimidazole, CB: carboxybetaine ethylimidazole, and LiTFSI: lithium bis(trifluoromethylsulfonyl)-imide). The simulation systems include two Li+ : O(EO10) molar ratios: 1 : 6 and 1 : 18. The simulation results show that all three zwitterionic molecules reduce the Li+-EO10 coordination number in the order of MPC > CB > SB. In addition, nearly 10% of Li+ exclusively coordinates with MPC molecules, only 2-4% of Li+ exclusively cooridinates with CB molecules, while no Li+ exclusively coordinates with SB molecules. MPC molecules also present the most stable Li+ coordination among the three zwitterionic molecules. Our simulations indicate that zwitterionic molecule additives may benefit a high Li+ concentration environment. At a low Li+ concentration, all three zwitterionic molecules reduce the diffusion coefficient of Li+. However, at a high Li+ concentration, only SB molecules reduce the diffusion coefficient of Li+.

Visible Light Induces Site-Specific Oxidative Heavy Chain Fragmentation of a Monoclonal Antibody (IgG1) Mediated by an Iron(III)-Containing Histidine Buffer

Fragmentation of therapeutic monoclonal antibodies represents a critical quality attribute. Here, we report a novel visible light-induced heavy chain fragmentation of IgG1 mediated by an Fe(III)-containing histidine (His) buffer. Based on non-reducing sodium dodecylsulfate-polyacrylamide gel electrophoresis and mass spectrometry analysis, IgG1 fragments with apparent molecular weights of ∼130, ∼110, and ∼22 kDa were detected in photo-irradiated samples and were mechanistically rationalized with an oxidative cleavage at Thr259. Specifically, the reactions are proposed to involve the generation of an intermediary alkoxyl radical, which undergoes β-cleavage to yield a glycyl radical. The latter either converts into Gly or adds oxygen and follows a peroxyl radical chemistry. The cleavage process requires the presence of His, while only negligible yields of cleavage products are formed when His is replaced by acetate, succinate, or phosphate buffer. Importantly, the fragmentation can be prevented by ethylenediaminetetraacetic acid (EDTA) only when the EDTA concentrations are in significant excess over the concentrations of Fe(III) and proteins, suggesting a strong binding between Fe(III) and IgG1.

Insight into Different Stages of Steroid Degradation in Thermophilic Saccharopolyspora hirsuta VKM Ac-666T Strain.

Steroids are abundant molecules in nature, and various microorganisms evolved to utilize steroids. Thermophilic actinobacteria play an important role in such processes. However, very few thermophiles have so far been reported capable of degrading or modifying natural sterols. Recently, genes putatively involved in the sterol catabolic pathway have been revealed in the moderately thermophilic actinobacterium Saccharopolyspora hirsuta VKM Ac-666T, but peculiarities of strain activity toward sterols are still poorly understood. S. hirsuta catalyzed cholesterol bioconversion at a rate significantly inferior to that observed for mesophilic actinobacteria (mycobacteria and rhodococci). Several genes related to different stages of steroid catabolism increased their expression in response to cholesterol as was shown by transcriptomic studies and verified by RT-qPCR. Sequential activation of genes related to the initial step of cholesterol side chain oxidation (cyp125) and later steps of steroid core degradation (kstD3, kshA, ipdF, and fadE30) was demonstrated for the first time. The activation correlates with a low cholesterol conversion rate and intermediate accumulation by the strain. The transcriptomic analyses revealed that the genes involved in sterol catabolism are linked functionally, but not transcriptionally. The results contribute to the knowledge on steroid catabolism in thermophilic actinobacteria and could be used at the engineering of microbial catalysts.

Genetic diversity and proteomic analysis of vegetable soybean (Glycine max (L.) Merrill) accessions grown in mineral and BRIS soils

Knowledge of the molecular mechanisms of response to environmental stress is fundamental for the development of genetically stress-tolerant crops. This study aims to find vegetable soybean accessions tolerant to cultivation in stressful tropical environments. Fourteen accessions of the vegetable soybean (Glycine max (L.) Merrill) were grown in mineral and beach ridges interspersed with swale (BRIS) soils. The genetic diversity, estimated using inter-simple sequence repeat (ISSR) markers, revealed 42.50% polymorphism and was regarded as moderate. The unweighted pair-group method arithmetic average (UPGMA) analysis allocated the tested accessions into five major clusters at a similarity coefficient level of 0.43. The lowest values of the genetic distance were between IIUMSOY11 and IIUMSOY13 & IIUMSOY13 and IIUMSOY14, indicating that these accessions were more genetically distant from the other accessions. Ten differentially expressed proteins were identified in the three selected accessions IIUMSOY1, IIUMSOY11 and IIUMSOY14 using mass spectrometry, revealing a unique expression of the proteins involved in the storage, flavonoid metabolism, protein modification, oxidative stress defence, carbohydrate metabolism and respiratory chain. The findings may be valuable for the selection of genetically diverse accessions, to enhance the breeding of vegetable soybean genotypes suitable for stressful tropical environments.

Design and manufacturing of cost-effective tannin-based polyurethane foam as an efficient and reusable absorbent for oil and solvents

Developing low-cost, efficient, and renewable polyurethane as an efficient absorbent for oil spill clean-ups is still a challenge. Herein, tannin-based polyether polyol (MTEBP) was synthesized using tannin extract as feedstocks through graft-liquefaction, and then to produce tannin extract-based foams (MTPFs). Benefiting from the better hydrophobicity, and porosity of MTPFs, the adsorption capacities of modified foam with 100 wt%MTEBP (MTPF100) to soybean oil , xylene , dichloromethane, n -hexane and cyclohexane increased by 53.5%, 57.9%, 115.1%, 83.5%, and 97.2%, respectively, and could be recycled stably for 6 times, compared with the unmodified foam (RPUF). In addition, the mechanical properties of MTPFs including compressive and flexural strength are comparable or superior to that of RPUF, which could be ascribed to the good crosslink density and flexible long-polypropylene oxide chain in the structure of MTEBP. Thermal analysis showed that partial or complete substitution of polyols (SA-380) by MTEBP delayed the first onset of degradation of the polyurethane foams, providing better thermal stability. Particularly, the initial degradation temperature of MTPF100 was immensely increased (209.5 °C), compared to that of the reference RPUF (121.4 °C). This work affords a feasible and sustainable strategy to fabricate the biobased, eco-friendly, high adsorption capacities tannin-based materials for oil spill clean-ups. • Tannin extract was successfully liquefied via alkoxylation under mild conditions. • Spill clean-up foam (MTPFs) was prepared using liquefied tannin extract as raw material. • Oil/organic solvents absorption performances of MTPFs were improved obviously, compared with raw foam. • Excellent reusability and oil/water selectivity is displayed by MTPFs sorbent, after 6 cycles.

A Biocompatible Liquid Pillar[n]arene-Based Drug Reservoir for Topical Drug Delivery.

Advanced external preparations that possess a sustained-release effect and integrate few irritant elements are urgently needed to satisfy the special requirements of topical administration in the clinic. Here, a series of liquid pillar[n]arene-bearing varying-length oligoethylene oxide chains (OEPns) were designed and synthesized. Following rheological property and biocompatibility investigations, pillar[6]arene with triethylene oxide substituents (TEP6) with satisfactory cavity size were screened as optimal candidate compounds. Then, a supramolecular liquid reservoir was constructed from host-guest complexes between TEP6 and econazole nitrate (ECN), an external antimicrobial agent without additional solvents. In vitro drug-release studies revealed that complexation by TEP6 could regulate the release rate of ECN and afford effective cumulative amounts. In vivo pharmacodynamic studies confirmed the formation of a supramolecular liquid reservoir contributed to the accelerated healing rate of a S. aureus-infected mouse wound model. Overall, these findings have provided the first insights into the construction of a supramolecular liquid reservoir for topical administration.

Perylene-Mediated Electron Leakage in Respiratory Chain to Trigger Endogenous ROS Burst for Hypoxic Cancer Chemo-Immunotherapy.

Perylene derivatives can be stimulated by the hypoxic tumor microenvironment to generate radical anion that is proposed to arouse electron exchange with oxidizing substance, and in turn, realize reactive oxygen species (ROS) burst. Here, three perylene therapeutic agents, PDI-NI, PDIB-NI, and PDIC-NI, are developed and it is found that the minimum lowest unoccupied molecular orbital (LUMO) energy level makes PDIC-NI most easily accept electrons from the oxidative respiratory chain to form lots of anions, and the resultant maximum ROS generation, establishing an unambiguous mechanism for the formation of perylene radical anions in the cell, presents solid evidence for LUMO energy level determining endogenous ROS burst. Stirringly, PDIC-NI-induced ROS generation arouses enhanced mitochondrial oxidative stress and concurrently activates immunogenic cell death (ICD), which not only efficiently kills lung tumor cells but also reprograms immunosuppressive tumor microenvironment, including the cytokine secretion, dendritic cell maturation, as well as cytotoxic T lymphocytes activation, to inhibit the growth of xenografted and metastasis tumor, presenting a proof-of-concept demonstration of perylene that acts as an integrated therapeutic agent to well realize hypoxia-activated chemotherapy with ICD-induced immunotherapy on lung cancer.

Abstract 12168: Pi3kγ is a Key Modulator of Cardiac Metabolism Rewiring Occurring in Doxorubicin-Treated Mice

Introduction: Doxorubicin (DOX) is a potent chemotherapeutic drug, whose use is hampered by the onset of long-term cardiotoxicity and lack of effective therapeutic approaches. Recently, metabolic perturbations have emerged as an early predictor factor of cardiac dysfunction, but how DOX affects cardiac metabolism is still unknown. We have previously demonstrated that phosphoinositide 3-kinase γ (PI3Kγ) is a major driver of DOX-evoked cardiotoxicity through mitophagy inhibition and accumulation of dysfunctional mitochondria. Hypothesis: Here we sought to explore the role of PI3Kγ in modulating cardiac metabolism upon DOX administration. Methods: Metabolomic analysis, glycolysis and oxidative phosphorylation were measured in whole hearts from wild-type (WT) and knock-in mice expressing a kinase-inactive PI3Kγ (kinase-dead; KD) treated with DOX (4 mg/kg on day 0, 7 and 14). Similar analyses were performed in WT and KD hearts infected with AAV9-shATG7 to explore the role of autophagy. Moreover, glucose uptake and GLUT-4 expression on the plasma membrane were measured in WT and KD neonatal mouse cardiomyocytes (NMCs) exposed to 1μM DOX. Results: Metabolomic analysis revealed an increased level of succinate and malic acid in DOX-treated hearts, suggesting defects in the TCA cycle. In agreement, DOX promotes the accumulation of metabolites normally catabolised in the TCA cycle, such as aminoacids and pyruvate, indicating a severe mitochondria dysfunction. Accordingly, fatty acid oxidation and electron transport chain activity were impaired in DOX-treated hearts at day 3 and exacerbated at day 42 after DOX. At the same time, glycolysis was upregulated. These changes were prevented in KD animals. Interestingly, upon autophagy inhibition, KD mice lost their cardioprotection at the mitochondrial level, but they still failed to upregulate glycolysis. This suggests a new autophagy-independent mechanism through which PI3Kγ regulates glucose utilisation. In agreement with the pharmacological and genetic inhibition of PI3Kγ abrogates glucose uptake in NMCs and normalises the plasma membrane exposure of GLUT-4. Conclusions: Overall, these results promote PI3Kγ as a master regulator of metabolic rewiring occurring in DOX-treated cardiomyocytes.

Lightweight porous carbon/rGO/Ni chain composite with excellent microwave absorption performance and multi-functional properties

Melamine foam was converted into porous carbon by high-temperature carbonization and then composited with reduced graphene oxide(rGO) and Ni chains by impregnation, freeze-drying, and high-temperature reduction, resulting in porous carbon/rGO composites and porous carbon/rGO/Ni chain composites. The electrical conductivity, wettability and wave-absorbing properties of the composites were investigated. The results show that the electrical conductivity of the composites is significantly improved, up to 2.29 mS/mm. This is because rGO has good electrical conductivity. In addition, When the thickness is 5.5 mm, the minimum reflection loss of the MF-3rGO sample of − 29.9 dB is obtained at 5.84 GHz and the effective bandwidth is 2.08 GHz. This is because rGO nanosheets have strong conductance loss. The addition of a small amount of Ni chains can tune the impedance matching ability of the composites. When the Ni chain content is 0.12 g, the optimum reflection loss of the MF-3rGO-0.12Ni is − 32.6 dB at 16.72 GHz with a thickness of 2 mm, and the effective bandwidth is 4 GHz. Meanwhile, the porous carbon/rGO composites and porous carbon/rGO/Ni chain composites have good hydrophobicity and can be used in humid environments. Therefore, the porous carbon composites prepared by melamine foam can be widely used in the field of electromagnetic wave absorption.

Interface of polymers grafted on silica: Organization of the interfacial layer in presence and absence of solvent

The 1H NMR technique is used to study the behaviour of the poly (ethylene oxide) (PEO) chains grafted chemically on silica in the presence or not of solvent. A noticeable influence of the different physicochemical parameters on the conformation of the grafted macromolecules is evinced. Different models are proposed for different lengths of grafted polymer chains on the surface in the absence and presence of a solvent. Without solvent, the macromolecules lie very flat and the layer is more organized. In the presence of a solvent, the chains spread out and adopt a more extended conformation and the local concentration of monomers decreases.