人造麝香的危害性及其残留检测方法研究进展

综述了近年来人造麝香的危害性及其残留检测方法的研究进展。对化妆品、水、大气、土壤和药物中人造麝香的前处理方法和检测方法进行了比较,同时对此领域的发展方向进行了展望(引用文献31篇)。     

说“弛豫”

"弛豫"是高分子物理课程中最重要的概念之一。作为"弛豫"的同义语,"松弛"一词应用更为普遍。与"弛豫"或"松弛"相关的术语有多个,如弛豫过程、松弛时间谱、力学松弛、介电松弛、应力松弛和次级松弛等。本文将这些术语集中在一起,分别阐释了其内涵。通过辨析,学习者就可以很好地理解这些概念,从而不会因其名称相近而造成混淆。弛豫现象是物质内部的分子运动在宏观上的一种表现,从绝对的意义上来说,任何物质都存在弛豫现象。但是,在所有的物质中,聚合物的弛豫现象表现最为突出。文章最后揭示了聚合物弛豫现象的分子机理。     

Construction of metal–organic frameworks from 3-(6-oxo-6,9-dihydro-1H-purin-1-yl)propionate

A series of metal–organic frameworks built from a propionate-functionalized purine-containing ligand 3-(6-oxo-6,9-dihydro-1H-purin-1-yl)propanoic acid (H₂L), {[La(HL)₃(H₂O)₂]·2H₂O}_n (1), {[Ce(HL)₃(H₂O)₂]·4H₂O}_n (2), [Co(HL)₂(H₂O)₂]_n (3), {[Cd(L)(H₂O)]·0.5H₂O}_n (4) and {[Pb(HL)(C₂O₄)_0.5(H₂O)]·2H₂O}_n (5), was synthesized and characterized. Isostructural 1 and 2 have polymeric chain structures further linked into 3-D porous supramolecular frameworks with 1-D open channels through complicated interchain hydrogen bonding interactions. At 77 K and 1 bar, the dehydrated porous materials 1 and 2 show adsorption behaviors with maximum nitrogen uptakes of 14 and 23 mL g^?1, respectively. Complexes 3–5 are 2-D coordination polymers but have different topological structures. Metallohelicate 3 has (4,4) nets composed of left- and right-handed metal–organic helices sharing the common metal centers, but metallohelicate 4 possesses (4·8²) topology and 5 has 6³-topological structure. In 3 and 5, the polymeric layers are further assembled through regular interlayer hydrogen bonding interactions to form 3-D supramolecular frameworks. Additionally, the thermostabilities of 1–5 as well as the magnetism of 3 were also investigated.     

Upgrading Solid Digestate from Anaerobic Digestion of Agricultural Waste as Performance Enhancer for Starch-Based Mulching Biofilm

Developing a green and sustainable method to upgrade biogas wastes into high value-added products is attracting more and more public attention. The application of solid residues as a performance enhancer in the manufacture of biofilms is a prospective way to replace conventional plastic based on fossil fuel. In this work, solid digestates from the anaerobic digestion of agricultural wastes, such as straw, cattle and chicken manures, were pretreated by an ultrasonic thermo-alkaline treatment to remove the nonfunctional compositions and then incorporated in plasticized starch paste to prepare mulching biofilms by the solution casting method. The results indicated that solid digestate particles dispersed homogenously in the starch matrix and gradually aggregated under the action of a hydrogen bond, leading to a transformation of the composites to a high crystalline structure. Consequently, the composite biofilm showed a higher tensile strength, elastic modulus, glass transition temperature and degradation temperature compared to the pure starch-based film. The light, water and GHG (greenhouse gas) barrier properties of the biofilm were also reinforced by the addition of solid digestates, performing well in sustaining the soil quality and minimizing N₂O or CH₄ emissions. As such, recycling solid digestates into a biodegradable plastic substitute not only creates a new business opportunity by producing high-performance biofilms but also reduces the environmental risk caused by biogas waste and plastics pollution.     

Cyclized oligomer of tetracyanoquinodimethane-tetrathiafulvalene (TCNQ-TTF): a versatile macrocyclic molecule by DFT calculations

Journal of Inclusion Phenomena and Macrocyclic Chemistry - The combination of the electron donor and acceptor into a donor–acceptor system can transform the intermolecular charge transfer...     

Separation of heart rate variability components of the autonomic nervous system by utilizing principal dynamic modes

This work introduces a modified Principal Dynamic Modes (PDM) methodology using eigenvalue/eigenvector analysis to separate individual components of the sympathetic and parasympathetic nervous contributions to heart rate variability. We have modified the PDM technique to be used with even a single output signal of heart rate variability data, whereas the original PDMs required both input and output data. This method specifically accounts for the inherent nonlinear dynamics of heart rate control, which the current method of power spectrum density (PSD) is unable to do. Propranolol and atropine were administered to normal human volunteers intravenously to inhibit the sympathetic and parasympathetic activities, respectively. With separate applications of the respective drugs, we found a significant decrease in the amplitude of the waveforms that correspond to each nervous activity. Furthermore, we observed near complete elimination of these dynamics when both drugs were given to the subjects. Comparison of our method to the conventional low/high frequency ratio of PSD shows that PDM methodology provides much more accurate assessment of the autonomic nervous balance by separation of individual components of the autonomic nervous activities. The PDM methodology is expected to have an added benefit that diagnosis and prognostication of a patient's health can be determined simply via a non-invasive electrocardiogram.     

O-GlcNAcylation mapping of single living cells by in situ quantitative SERS imaging

O-GlcNAcylation is involved in many biological processes including cancerization. Nevertheless, its in situ quantification in single living cells is still a bottleneck. Here we develop a quantitative SERS imaging strategy for mapping the O-GlcNAcylation distribution of single living cells. O-GlcNAcylated compounds (OGCs) can be quantified through their in situ azide labeling and then a click reaction competing with azide and Raman reporter labeled 15 nm-gold nanoparticles (AuNPs) for linking to dibenzocyclooctyne labeled 40 nm-AuNPs to produce OGC-negatively correlated SERS signals. The calibration curve obtained in vitro can be conveniently used for detecting OGCs in different areas of single living cells due to the negligible effect of cell medium on the click linkage and Raman signal. This method has been successfully applied in mapping O-GlcNAcylation distribution in different cell lines and monitoring O-GlcNAcylation variation during cell cycling, which demonstrate its great practicability and expansibility in glycosylation related analysis.

A quantitative SERS imaging strategy is developed for O-GlcNAcylation mapping of single living cells through a competitive click reaction.     

Synthesis of Phenylboronic Acid-Functionalized Magnetic Nanoparticles for Sensitive Soil Enzyme Assays

Soil enzymes, such as invertase, urease, acidic phosphatase and catalase, play critical roles in soil biochemical reactions and are involved in soil fertility. However, it remains a great challenge to efficiently concentrate soil enzymes and sensitively assess enzyme activity. In this study, we synthesized phenylboronic acid-functionalized magnetic nanoparticles to rapidly capture soil enzymes for sensitive soil enzyme assays. The iron oxide magnetic nanoparticles (MNPs) were firstly prepared by the co-precipitation method and then functionalized by (3-aminopropyl)triethoxysilane, polyethyleneimine and phenylboric acid in turn, obtaining the final nanoparticles (MNPPBA). Protein-capturing assays showed that the functionalized MNPs had a much higher protein-capturing capacity than the naked MNPs (56% versus 6%). Moreover, MNPPBA almost thoroughly captured the tested enzymes, i.e., urease, invertase, and alkaline phosphatase, from enzyme solutions. Based on MNPPBA, a soil enzyme assay method was developed by integration of enzyme capture, magnetic separation and trace enzyme analysis. The method was successfully applied in determining trace enzyme activity in rhizosphere soil. This study provides a strategy to sensitively determine soil enzyme activity for mechanistic investigation of soil fertility and plant–microbiome interaction.     

An Fc variant with two mutations confers prolonged serum half-life and enhanced effector functions on IgG antibodies

The pH-selective interaction between the immunoglobulin G (IgG) fragment crystallizable region (Fc region) and the neonatal Fc receptor (FcRn) is critical for prolonging the circulating half-lives of IgG molecules through intracellular trafficking and recycling. By using directed evolution, we successfully identified Fc mutations that improve the pH-dependent binding of human FcRn and prolong the serum persistence of a model IgG antibody and an Fc-fusion protein. Strikingly, trastuzumab-PFc29 and aflibercept-PFc29, a model therapeutic IgG antibody and an Fc-fusion protein, respectively, when combined with our engineered Fc (Q311R/M428L), both exhibited significantly higher serum half-lives in human FcRn transgenic mice than their counterparts with wild-type Fc. Moreover, in a cynomolgus monkey model, trastuzumab-PFc29 displayed a superior pharmacokinetic profile to that of both trastuzumab-YTE and trastuzumab-LS, which contain the well-validated serum half-life extension Fcs YTE (M252Y/S254T/T256E) and LS (M428L/N434S), respectively. Furthermore, the introduction of two identified mutations of PFc29 (Q311R/M428L) into the model antibodies enhanced both complement-dependent cytotoxicity and antibody-dependent cell-mediated cytotoxicity activity, which are triggered by the association between IgG Fc and Fc binding ligands and are critical for clearing cancer cells. In addition, the effector functions could be turned off by combining the two mutations of PFc29 with effector function-silencing mutations, but the antibodies maintained their excellent pH-dependent human FcRn binding profile. We expect our Fc variants to be an excellent tool for enhancing the pharmacokinetic profiles and potencies of various therapeutic antibodies and Fc-fusion proteins.Subject terms: Antibody therapy, Molecularly targeted therapy, Drug development