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Organic and polymer fluorescent nanomaterials are a frontier research focus. Here in this work, a series of fluorinated zwitterionic random copolymers end‐attached with a quasi‐chromophoric group of pyrene or tetraphenylethylene (TPE) are well synthesized via atom transfer radical polymerization with activators regenerated by electron transfer (ARGET ATRP). Those random copolymers with total degree of polymerization 100 or 200 are able to produce fluorescent single‐chain nanoparticles (SCNPs) through intra‐chain self‐folding assembly with quite uniform diameters in the range of 10–20 nm as characterized by dynamic light scattering and transmission electron microscopy. By virtue of the segregation or confinement effect, both SCNPs functionalized with pyrene or TPE group are capable of emitting fluorescence, with pyrene tethered SCNPs exhibiting stronger fluorescence emission reaching the highest quantum yield ≈20%. Moreover, such kind of fluorescent SCNPs manifest low cytotoxicity and good cell imaging performance for Hela cells. The creation of fluorescent SCNPs through covalently attached one quasi‐chromophore to the end of one fluorinated zwitterionic random copolymer provides an alternative strategy for preparing polymeric luminescence nanomaterials, promisingly serving as a new type of fluorescent nanoprobes for biological imaging applications. [ABSTRACT FROM AUTHOR]

Leaf Area Index (LAI) is one of the most important biophysical parameters of vegetation, and its dynamic changes can be used as a reflective indicator and differentiation basis of vegetation function. In this study, a VCA–MLC (Vertex Component Analysis–Maximum Likelihood Classification) algorithm is proposed from the perspective of multi-temporal satellite LAI image classification to monitor and quantify the spatial and temporal variability of vegetation dynamics in China since 2000. The algorithm extracts the vegetation endmembers from 46 multi-temporal images of MODIS LAI in 2011 without the aid of other a priori knowledge and uses the maximum likelihood classification method to select the categories that satisfy the requirements of the number of missing periods, absolute distance, and relative distance for the rest pixels to be classified, ultimately dividing the vegetation area of China into 10 vegetation zones called China Vegetation Functional Zones (CVFZ). CVFZ outperforms MCD12Q1 and CLCD land cover datasets in the overall differentiation of vegetation functions and can be used synergistically with other land cover datasets. In this study, CVFZ is used to cut the constant vegetation-type pixels of MCD12Q1 during 2001–2022. The results of the LAI mean time series decomposition of each subregion using the STL (Seasonal-Trend Decomposition based on Loess) method show that the rate of vegetation greening ranges from 9.02 × 10−4 m2m−2yr−1 in shrubland subregions to 2.34 × 10−2 m2m−2yr−1 in savanna subregions. In relative terms, the average greening speed of forests is moderate, and savannas tend to have the fastest average greening speed. The greening speed of grasslands and croplands in different zones varies widely. In contrast, the average greening speed of shrublands is the slowest. In addition, CVFZ detected grasslands with one or two phenological cycles, broadleaf croplands with one or two phenological cycles, and shrublands with no apparent or one phenological cycle. [ABSTRACT FROM AUTHOR]

Long-term blue light exposure beyond the risk limit is an important factor that causes retinal degenerative diseases, and damage to the retinal pigment epithelium is the key source of retinal light damage. In this study, we investigated the damaging effects of 448 nm blue light on human retinal pigment epithelial (ARPE-19) cells and the mode of apoptosis. ARPE-19 cells were irradiated with 25 mW/cm² blue light for 3, 6, 9 and 12 hours, and cell activity was detected immediately by Calcein AM staining 24 h after irradiation. RT-PCR was used to examine the expression of necrotic apoptosis related genes 24 hours after irradiation, and the Western blotting was used to examine the expression of necroptosis-related and DNA-damage related proteins. The cell morphology changed significantly in the 9-hour and 12-hour groups, the cells swelled, the intercellular space was enlarged, and a large number of cell fragments and non-adhesive cells were observed. Compared with the normal group, the expression levels of the necroptosis-related genes RIPK1 and RIPK3 were significantly higher 3-9 hours after blue light irradiation, and reached the maximum value at 9 h. The expression levels of necroptosis-related proteins RIPK1, RIPK3, P-MLKL markers significantly increased with the increase of irradiation time after 6 ~ 12 h blue light irradiation, and reached the highest value at 12 h. The expression level of DNA damage-related γ-H2AX protein increased significantly after 3 ~ 12 h blue light irradiation, and reached the highest value at 12 h. The expression of necroptosis-related genes reached the maximum after 9 hours of blue light irradiation, while the expression of necroptosis-related proteins reached the maximum after 12 hours irradiation. It was speculated that 25 mW/cm² blue light irradiation for 12 h may cause the necroptosis in ARPE-19 cells, and the degree of DNA damage may be related to the occurrence of necroptosis. [ABSTRACT FROM AUTHOR]

Abstract: Through the construction of an organic photocatalysis system, photoredox catalyst (PC)/additive, where PC stands for photoredox catalyst, an organocatalyzed step transfer‐addition and radical‐termination (O‐START) polymerization irradiated by blue LED light at room temperature is realized. Different types of α,ω‐diiodoperfluoroalkane A and α,ω‐unconjugated diene B are copolymerized through O‐START efficiently, and generate various kinds of functional semifluorinated polymers, including polyolefins and polyesters. The process is affected by several factors; solvents, additives, and feed ratio of A to B. After optimization of all these components, the polymerization efficiency is greatly improved, generating polymers with both relatively high yield and molecular weight. Considering the mild reaction condition, easy operation process, and free‐of‐metal‐catalyst residues in the polymer product, the organocatalytic polymerization strategy provides a simple and efficient approach to functional semifluorinated polymer materials and hopefully opens up their application in high‐tech fields. [ABSTRACT FROM AUTHOR]

A new polymerization method, termed as step transfer-addition and radical-termination, is developed for the step-growth radical polymerization of α,ω-unconjugated dienes under irradiation of visible light at room temperature (25 °C) for the first time. α,ω-Diiodoperfluoroalkane monomers (signified as A) are added onto α,ω-unconjugated dienes (signified as B) alternatively and efficiently with the generation of perfluorocarbon-containing alternating copolymers ( AB) n. Based on the combined analyses of polymerization kinetics and NMR spectra (1H and 19F), the mechanism of the novel polymerization method, including the side reaction, is proposed. This novel polymerization method provides a new strategy not only for the step-growth radical polymerization of α,ω-unconjugated dienes but also for the construction of high molecular weight perfluorocarbon-containing alternating copolymers. [ABSTRACT FROM AUTHOR]

Azobenzene-containing polymers (azopolymers) are a kind of intensively explored fascinating photoresponsive materials, liquid crystalline (LC) azopolymers with excellent film-forming, ordered structure and self-repairing capability are endowed with enhanced photoisomerization and photoalignment characteristics capable of developing into photo-modulated smart surfaces. Here in this work, two azobenzene side-chain LC polynorbornenes of PNB-Azo-n with different DP of n = 50 and 100 have been well synthesized through ring-opening metathesis polymerization (ROMP). The polynorbornene backbone of less flexibility with larger spacing between adjacent azobenzene side groups endows stronger inhibition for H-aggregation and better photoresponsiveness. The high-DP azopolynorbornene of PNB-Azo-100 thin films well behave as command surface for the upper layer nematic LC molecules thanks to their better performance in photoisomerization and photoalignment, together with their good compatibility and dissolution-resistance to the nematic LC mixture of E7. Selectively optically readable LC graphic writings at normal size through various photomasks have been demonstrated, and higher grid resolution up to sub-ten micrometer with a digital micromirror device (DMD) based dynamic photopatterning system has been achieved. Therefore, such kind of LC azopolynorbornenes demonstrate promising applications in LC photoalignment system and photoresponsive devices for potential anti-forgery document security and smart card technology. Image 1 • Synthesis of LC polynorbornenes with side-chain azobenzene via ROMP (DP 50, 100). • Semi-rigid polynorbornene inhibiting H-aggregation and promoting photoresponse. • Photoaligned high-DP azopolymer thin films as command surface for LC E7 patterning. • High grid resolution up to sub-ten-micrometer from DMD based dynamic photopatterning. • LC photoalignment and photoresponsive systems promising for anti-forgery application. [ABSTRACT FROM AUTHOR]

Microcystin is a cyclic heptapeptide compounds which could cause female mammals' reproductive toxicity. Ovarian granulosa cells (GCs) are essential for the growth and development of follicles. In this study, after mouse granulosa cells (mGCs) treated with microcystin-LR (MC-LR) for 48 h, microRNAs (miRNAs) and mRNAs microarray technology were adopted to detect the expression of miRNAs and mRNAs. The results showed that 125 miRNAs and 283 mRNAs changed significantly, including 50 miRNAs down-regulated (fold change < −1.2), 75 miRNAs up-regulated (fold change > 1.2), 162 mRNAs down-regulated (fold change < −1.15) and 121 mRNAs up-regulated (fold change > 1.15) in treated group compared with the control group. Functional analysis showed that significant changed miRNAs and mRNAs are mainly involved in proliferation, apoptosis, immunity, metabolism and other biological processes of mGCs. By KEGG pathways analysis, we found that differentially expressed miRNAs and mRNAs mainly participated in apoptosis, formation of cancer, proliferation, production of hormones and other related signal pathways. miRNA-gene network analysis indicated that miR-29b-3p, miR-29a-3p, miR-29c-3p, miR-1906, miR-182-5p, growth factor receptor bound protein 2-associated protein 2 (Gab2), FBJ osteosarcoma oncogene (Fos), insulin-like growth factor 1 (Igf1), mannosidase 1, alpha (Man1a) are key miRNAs and genes. The microarray results were validated by real-time fluorescent quantitative PCR (qRT-PCR). [ABSTRACT FROM AUTHOR]

Liquid crystalline elastomers (LCEs) combine the ordering character of a liquid crystal and the elasticity of a polymer network. The development of fully light-driven LCE-based soft actuators with good reshapeability and recyclability is in high demand. In this work, we prepared SWCNT/LCE composite films through the introduction of allyl sulfide-based dynamic covalent crosslinks in the LCE matrix and the well-dispersed filler single-walled carbon nanotubes (SWCNTs) with a strong photothermal effect. The SWCNT/LCE composite films were facilely fabricated with reorientation and remouldable capabilities regulated by 405 nm visible light. The monodomain composite films demonstrated multimode actuations of contraction, bending, curling, stretching recovery, and even shape memory driven by 808 nm near-infrared (NIR) light. Moreover, the monodomain spiral ribbon or stretching flat strip and the original polydomain composite film can be readily transformed into each other, and reshaped through easily achievable fabrication conditions. Therefore, the well-prepared SWCNT/LCE composite films with exchangeable covalent crosslinks showed promise as candidates for the development of multimode NIR photomechanical soft actuators with fully light-driven controllability and good remouldability. [ABSTRACT FROM AUTHOR]

In this study, iron-mediated activator generated by electron transfer for atom transfer radical polymerization of methyl methacrylate was carried out using two different types of salts, acidic hydroxylamine hydrochloride and basic sodium bisulfite as the reducing agents, ethyl 2-bromoisobutyrate as an initiator, FeCl·6HO as a catalyst and triphenylphosphine (PPh) as a ligand. The polymerization could be carried out in the presence of a limited amount of oxygen (air) and showed highly efficient catalyst activity. The living features were confirmed by the polymerization kinetics, analysis of chain end, and chain-extension experiment. [ABSTRACT FROM AUTHOR]

• Ultrasmall Pt nanodots supported on Polymerized Ionic Liquid wrapped MWCNTs. • Pt-PIL-MWCNTs displaying excellently peroxidase-like activity. • Fast and distinguished color change, as well as high stability to harsh conditions. • Facile colorimetric detection of glucose in real blood samples. Pt nanoparticles have been actively researched as enzyme mimetic nanomaterials for bioanalysis, catalysis and environment treatment over the past years. However, the general issues with individual Pt nanoparticles are stabilization and reproducibility, which lead to the search of Pt based nanocomposite to enhance their activity. In this work, we developed a novel kind of surfactant-free nanocomposites (Pt-PIL-MWCNTs) containing Pt nanodots highly dispersed on polymerized ionic liquid wrapped multi-walled carbon nanotubes, and demonstrated their intrinsic peroxidase-like activity for use in colorimetric detection of hydrogen peroxide and glucose. The Pt-PIL-MWCNTs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The as-prepared Pt-PIL-MWCNTs were used to catalyze the oxidation of a peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) by H 2 O 2 to the oxidized colored product. Based on the excellent catalytic activity of Pt-PIL-MWCNTs, two colorimetric sensors for detecting H 2 O 2 and glucose, respectively, were constructed with a wide linear range of 10–1000 μM (for H 2 O 2) and 160–900 μM (for glucose), as well as a relative lower limit of detection [5.5 μM (for H 2 O 2) and 50 μM (for glucose)]. The excellent performance of the sensor exhibited that the Pt-PIL-MWCNTs composite could be used as a promising mimetic peroxidase for applications in biosensing. [ABSTRACT FROM AUTHOR]