Enzymatic Oligomerization of <i>p</i>‑Methoxyphenol and Phenylamine Providing Poly(<i>p</i>‑methoxyphenol-phenylamine) with Improved Antioxidant Performance in Ester Oils

Poly­(<i>p</i>-methoxyphenol-phenylamine), denoted as P­(MOP-PA), was synthesized via the enzymatic oligomerization of <i>p</i>-methoxyphenol and phenylamine monomers in the presence of horseradish. The structure of the as-synthesized product was confirmed by Fourier transform infrared spectrometry, time-of-flight mass spectrometry, and elemental analysis, and the oligomerization process was studied by high-performance liquid chromatography. Moreover, the antioxidation behavior of P­(MOP-PA) as an antioxidant in several ester oils was evaluated by rotary oxygen bomb test and pressurized differential scanning calorimetry, and its antioxidant mechanism was discussed. It was found that, as the antioxidant in various base oils, P­(MOP-PA) exhibits excellent antioxidation ability at elevated temperatures of 150 and 210 °C. In addition, P­(MOP-PA) has an antioxidant ability that is better than that of poly­(<i>p</i>-methoxyphenol), and it exhibits an antioxidation ability in synthetic ester oil, such as di-iso-octyl sebacate, that is much better than that of several commonly used commercial hindered phenolic antioxidants

Tribological Properties of Tungsten Disulfide Nanoparticles Surface-Capped by Oleylamine and Maleic Anhydride Dodecyl Ester as Additive in Diisooctylsebacate

Oleylamine (OM) and maleic anhydride dodecyl ester (MADE, synthesized at our laboratory) were adopted as the surface modifiers to prepare OM/MADE-capped tungsten disulfide (WS₂) nanoparticles. An X-ray diffractometer and a transmission electron microscope were performed to analyze the microstructure and phase ingredients of the OM/MADE-capped WS₂ nanoparticles. Moreover, a four-ball friction and wear tester and a reciprocating tribometer were employed to evaluate the tribological properties of the surface-capped WS₂ nanoparticles as the lubricant additive in diisooctylsebacate (DIOS) from room temperature to 150 °C. The morphology of the worn steel surfaces and wear scars and their chemical states were investigated with a scanning electron microscope, three-dimensional profilometry, and an X-ray photoelectron spectroscope. Results show that OM-capped WS₂ nanoparticles nearly have no effect on the tribological properties of the DIOS base oil. The OM/MADE-capped WS₂ nanoparticles added in the same base stock at a concentration of 2.0% (mass fraction), however, exhibit good dispersibility and result in greatly improved tribological properties. The reason lies in that, after surface-capping by MADE containing polar group and OM containing coordination group, the OM/MADE-capped WS₂ particulates added in the base oil are well adsorbed on the sliding surfaces of the steel–steel contact to afford a chemisorption film with a low shear force. At the same time, OM/MADE-capped WS₂ nanoparticles as the additive in DIOS base oil take part in tribochemical reactions to form tribofilm composed of WO₃ and iron oxides on sliding surfaces, which also contributes to reducing the friction and wear of the steel sliding contact

DataSheet_1_Analysis of the response regulatory network of pepper genes under hydrogen peroxide stress.zip

Hydrogen peroxide (H2O2) is a regulatory component related to plant signal transduction. To better understand the genome-wide gene expression response to H2O2 stress in pepper plants, a regulatory network of H2O2 stress-gene expression in pepper leaves and roots was constructed in the present study. We collected the normal tissues of leaves and roots of pepper plants after 40 days of H2O2 treatment and obtained the RNA-seq data of leaves and roots exposed to H2O2 for 0.5–24 h. By comparing the gene responses of pepper leaves and roots exposed to H2O2 stress for different time periods, we found that the response in roots reached the peak at 3 h, whereas the response in leaves reached the peak at 24 h after treatment, and the response degree in the roots was higher than that in the leaves. We used all datasets for K-means analysis and network analysis identified the clusters related to stress response and related genes. In addition, CaEBS1, CaRAP2, and CabHLH029 were identified through a co-expression analysis and were found to be strongly related to several reactive oxygen species-scavenging enzyme genes; their homologous genes in Arabidopsis showed important functions in response to hypoxia or iron uptake. This study provides a theoretical basis for determining the dynamic response process of pepper plants to H2O2 stress in leaves and roots, as well as for determining the critical time and the molecular mechanism of H2O2 stress response in leaves and roots. The candidate transcription factors identified in this study can be used as a reference for further experimental verification.</p

Evaluation of Glycodendron and Synthetically Modified Dextran Clearing Agents for Multistep Targeting of Radioisotopes for Molecular Imaging and Radioimmunotherapy

A series of <i>N</i>-acetylgalactosamine-dendrons (NAG-dendrons) and dextrans bearing biotin moieties were compared for their ability to complex with and sequester circulating bispecific antitumor antibody streptavidin fusion protein (scFv₄-SA) <i>in vivo</i>, to improve tumor-to-normal tissue concentration ratios for multistep targeted (MST) radioimmunotherapy and diagnosis. Specifically, a total of five NAG-dendrons employing a common synthetic scaffold structure containing 4, 8, 16, or 32 carbohydrate residues and a single biotin moiety were prepared (NAGB), and for comparative purposes, a biotinylated-dextran with an average molecular weight of 500 kD was synthesized from amino-dextran (DEXB). One of the NAGB compounds, CA16, has been investigated in humans; our aim was to determine if other NAGB analogues (e.g., CA8 or CA4) were bioequivalent to CA16 and/or better suited as MST reagents. <i>In vivo</i> studies included dynamic positron-emission tomography (PET) imaging of ¹²⁴I-labeled-scFv₄-SA clearance and dual-label biodistribution studies following MST directed at subcutaneous (s.c.) human colon adenocarcinoma xenografts in mice. The MST protocol consists of three injections: first, a scFv₄-SA specific for an antitumor-associated glycoprotein (TAG-72); second, CA16 or other clearing agent; and third, radiolabeled biotin. We observed using PET imaging of the ¹²⁴I-labeled-scFv₄-SA clearance that the spatial arrangement of ligands conjugated to NAG (i.e., biotin linked with an extended spacer, referred to herein as long-chain (LC)) can impact the binding to the antibody in circulation and subsequent liver uptake of the NAG-antibody complex. Also, NAGB CA32-LC or CA16-LC can be utilized during MST to achieve comparable tumor-to-blood ratios and absolute tumor uptake seen previously with CA16. Finally, DEXB was equally effective as NAGB CA32-LC at lowering scFv₄-SA in circulation, but at the expense of reducing absolute tumor uptake of radiolabeled biotin