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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]

The purpose of the present study was to evaluate the effects of cordycepin (CA) on N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinomas (HCC) and explore its potential mechanisms. Mice were randomly assigned to four groups: control group, NDEA group, NDEA + CA (20 mg/kg) group, NDEA + CA (40 mg/kg) group. The animal of each group were given NDEA (100 ppm) in drinking water. One hour later, CA, which was dissolved in PBS, were intragastrically administered for continuous seven days. The results showed that CA reduced the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in liver and serum. CA also reduced the levels of interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α), methane dicarboxylic aldehyde (MDA), and stored the activity of superoxygen dehydrogenises (SOD) in serum. CA could obviously attenuate the hepatic pathological alteration. Furthermore, CA effectively inhibited the phosphorylations of phosphatidylinositol 3 kinase(PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR). In conclusion, our research suggested that CA exhibited protective effects on NDEA-induced hepatocellular carcinomas via the PI3K/Akt/mTOR pathway. [ABSTRACT FROM AUTHOR]

An effective Pd-catalyzed reduction of olefins in water using formic acid is disclosed. A wide range of saturated hydrocarbons are obtained with an excellent conversion and remarkable chemoselectivity under mild reaction conditions. This protocol is more advantageous and less cumbersome owing to the use of HCOOH as a hydrogen source, water as a solvent, and simple workup procedure. [ABSTRACT FROM AUTHOR]

1,4-Bis[4-(4-benzoyl-5-phenylisoxazol-3-yl)-3-methyl-1-phenylpyrazol-5-yloxy]benzene and its derivatives were synthesised. The antioxidant activities of these compounds were investigated in vitro assay systems, such as lipid peroxidation, 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethyl-1,3-benzothiazoline-6-sulfonic acid), superoxide, hydroxyl radicals scavenging and reducing power assay. The results show that the target compounds with nitro- and chloro-substituents at the 4-position of the benzene ring had more effective antioxidant power and better radical scavenging activity (RSA) (%) values when compared to those of butylated hydroxytoluene, trolox, caffeic acid and ascorbic acid, respectively. [ABSTRACT FROM AUTHOR]

Objective The objective of this article is to explore the feasibility of low injection rate and low contrast agent dose in three-dimensional rotational digital subtraction angiography (3D DSA) of the intracranial aneurysm. Materials and methods Fifty-one patients with suspected intracranial aneurysms were included. The catheter tip was kept within the internal carotid artery at the epistropheus level. Patients were divided into three groups randomly according to injection rate: group A (1.5 ml/s, n = 18), group B (2.0 ml/s, n = 18), and group C (3.0 ml/s, n = 15). The noise, signal-to-noise ratio (SNR), and carrier-to-noise ratio (CNR) of C2, C6, M1, and A1 segments were calculated. The continuous subtraction images and reconstructed images were evaluated by two technicians. Results No significant differences were found in noise between groups A and B, and groups A and C. Significant differences were found in the SNR and CNR of M1 and A1 segments between groups A and B, and groups B and C, but for C2 and C6 segments, they were not significant. Significant differences were found in the SNR and CNR of all segments between groups A and C. Significant differences were found in the contrast agent dose between all three groups. No significant differences were found in scores evaluated by two physicians between the three groups. Conclusion The personalized injection protocol of low injection rate and low contrast agent dose in 3D DSA of the intracranial aneurysm is feasible. The application of this protocol can reduce the dose of iodine and obtain satisfactory images. [ABSTRACT FROM AUTHOR]

A series of β-lactam-fused 1,5-benzothiazepine derivatives containing the quinoline moiety were synthesized via [2 + 2] cycloadditions reaction and the structures of the target compounds were confirmed by spectroscopic methods. These tricyclic heterocycles are promising candidates for drug discovery. [ABSTRACT FROM PUBLISHER]

On the basis of the spatial panel data of 2000, 2005, 2010, and 2015, this study uses a mixed geographically weighted regression model to explore the spatial distribution characteristics and influencing factors of the rural (permanent) population in Jiangxi Province, China. Results show that residents in the county area have a significant spatial positive autocorrelation, especially in the lake and mountain areas and the global Moran' I index is more than 0.05. The influence of social and economic factors presents spatial homogeneity. The effect of urbanization and per capita disposable income is negative, whereas that of agricultural output value and rural electricity consumption is positive. The influence of climate factors presents spatial heterogeneity. The influence coefficient of rainfall in 2015 ranges from [-0.061, 0.133], which has a negative effect on the southwest mountain areas and a positive effect on the northeast lake areas., The influence coefficient of temperature in 2015 ranges from [-0.110, 0.094], which has a positive effect on the southwest mountain areas and a negative effect on the northeast lake areas. The influence coefficients of wind speed and relative humidity range from [-0.090, 0.153] and [-0.069, 0.130] in 2015 respectively, which further reinforce this effect. Therefore, scholars should pay attention to the universal adaptability of economic and social factors. Moreover, they should consider the spatial difference of climatic factors to promote urbanization following the local conditions. Finally, policymakers and concerned non-governmental institutions should fully understand the sensitivity of the rural population in underdeveloped mountain areas to climate factors to promote their rational distribution. [ABSTRACT FROM AUTHOR]

Liquid crystal (LC) dimers with well‐defined composition and structure arouse broad attentions for their exhibiting LC properties beyond conventional low molar mass mesogens and serving as fascinating model compounds for LC polymers. Here in this work, a series of LC dimers bridged with a phosphonic group have been synthesized through a facile free radical mediated addition reaction between hypophosphorous acid and vinyl terminated cyanobiphenyl mesogens with variant length alkyl spacers. In addition, two esterified derivatives and a group of mono‐addition homologues with a terminal phosphonic acid group have also been prepared for comparison study. All the newly synthesized compounds exhibit monotropic nematic (N) phase with typical schlieren textures except for the LC dimer with the longest eleven‐methylene spacer, which surprisingly shows twist‐bend nematic (NTB) phase directly from the isotropic state upon cooling. Moreover, the thermal transition properties such as the nematic‐isotropic transition temperatures and associated entropy changes of the series LC dimers display a modest odd‐even effect. Furthermore, both the LC dimers and the mono‐addition homologues in N phase are quite easy to achieve homeotropic alignment upon annealing thanks to the supramolecular interactions between the introduced phosphonic acid group and the hydroxylated glass surface. This work thus provides a novel synthesis strategy for a class of LC materials bridged with a phosphonic acid group prone to further functionalization, which may serve as promising vertical alignment agents and pave the way for developing a new kind of functionalized LC materials of NTB phase. [ABSTRACT FROM AUTHOR]

The research on rural population distribution from a climate perspective is rare. Therefore, this study adopts this perspective and uses the ordinary least squares and spatial econometric models to explore the spatial distribution characteristics of the rural population in the Poyang Lake ecological economic zone. Results show that (1) a significant spatial autocorrelation is present in the distribution of rural population, and a spatial correlation exists between the population distribution and climatic factors, (2) the influence of climatic factors on the distribution of rural population in the Poyang Lake ecological economic zone is greater than that of economic factors, and (3) the annual average sunshine and annual average rainfall have a significant negative effect on the distribution of the regional rural population, which is contrary to the expectations., so we then analyze this negative effect on the regional rural population distribution. It is found that (1) the influence of climate factors on the distribution of rural population in lake area is far more than that of economic factors, and more consideration should be given to the influence of climate factors on the population distribution in the lake area, (2) different geographical capital and natural resource endowment, the influence of climate on micro-regional population distribution may be different from the general law, (3) the spatial measurement model which takes spatial dependence into account can reveal the influence of climate on rural population distribution more accurately. [ABSTRACT FROM AUTHOR]

Recently, surface‐enhanced Raman spectroscopy (SERS)‐based detection strategies have been widely developed for various practical applications, due to the near‐single‐molecule sensitivity and fingerprint identification capability. However, the qualitative and quantitative reliability of SERS have always been questioned when comparing with the classical GC/LC–MS techniques. Here, we systematically compared the properties of SERS and LC–MS in the detection of an unexpected herbicide in commercial herbicide. The result showed that, in the case of the ultra‐trace target detection in a complicated matrix, SERS‐based strategy exhibited high sensitivity and a much higher detection efficiency than the LC–MS‐based one, which demonstrated a more accurate quantifiability being facilitated with a well‐controlled sample pretreatment. Therefore, we showed that SERS could be further implemented in fast and on‐site detection tools for food safety application and environment monitoring. [ABSTRACT FROM AUTHOR]

Nanostructured gold electrodes have been widely used for electrochemical trace analysis of Hg2+ because Hg2+ has superior specificity for the formation of gold amalgam. However, it is still very challenging to achieve both high sensitivity and reproducibility, especially for real environmental water samples due to surface poisoning by organic residues. In this work, we developed two strategies for addressing these challenges. First, we added NaBr (with a final concentration of 0.01 M) to the analytes; this enhanced the sensitivity by two orders of magnitude and improved the reproducibility to be better than RSD <15% because of the synergetic interaction of Br− with Hg2+ and gold at the interface. Second, we developed a pre-oxidation method using a glassy carbon electrode to remove organic residue from the analyte before Hg2+ analysis. The combination of these two approaches results in an efficient, reliable, and fast electrochemical detection technique for on-site trace analysis of Hg2+ that is in concentrations lower than that required by WHO for drinking water. Image 1 • The batch preparation of a novel gold micro-nanostructured electrode. • The significantly improved sensitivity and reproducibility with the addition of small amount of Br−. • The effective removal of organic residues in ambient water by simple electrochemical oxidation pretreatment. [ABSTRACT FROM AUTHOR]

ABSTRACT Liquid crystalline block copolymers (LCBCPs) are fascinating for their combining molecular level liquid crystalline orders and microphase separated multidomain morphologies. Here in this article, a series of PEG-containing side-chain discotic LCBCPs of PEG- b- Pm- n with variant spacer length m = 6, 10 and degree of polymerization (DP) of discotic LC block from n = 10 to 45, have been well-synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization. The RAFT process mediated by macromolecular chain transfer agent (macroCTA) shows remarkable monomer concentration dependence. The influence of the introduced PEG block on the nano-scale microphase-segregation and mesophase organization is closely related to the side-chain triphenylene (TP) discogens stacking mode dependent on the spacer length. Wherein, the PEG- b- P6- n series with a six-methylene spacer exhibit consistent microphase separation with slightly disturbed yet ordered columnar structures. While for PEG- b- P10- n series with a longer ten-methylene spacer, the columnar organization in the copolymers is even improved in contrast with the low order of randomly TP stacking in their corresponding homopolymers. This work offers a viable and inspiring pathway for controlled synthesis of block copolymers with bulky side groups, as well as enhances in-depth understanding of the hierarchical superstructure organization in discotic units involved complex block copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2544-2553 [ABSTRACT FROM AUTHOR]

Background subtraction is a crucial step in the preprocessing of Raman spectrum. Usually, parameter manipulating of the background subtraction method is necessary for the efficient removal of the background, which makes the quality of the spectrum empirically dependent. In order to avoid artificial bias, we proposed an auto-adaptive background subtraction method without parameter adjustment. The main procedure is: (1) select the local minima of spectrum while preserving major peaks, (2) apply an interpolation scheme to estimate background, (3) and design an iteration scheme to improve the adaptability of background subtraction. Both simulated data and Raman spectra have been used to evaluate the proposed method. By comparing the backgrounds obtained from three widely applied methods: the polynomial, the Baek's and the airPLS, the auto-adaptive method meets the demand of practical applications in terms of efficiency and accuracy. [ABSTRACT FROM AUTHOR]

With the miniaturization of Raman spectrometers, Raman spectroscopy (including Surface-enhanced Raman spectroscopy) has been widely applied to various fields, especially towards rapid detection applications. In order to deal with the accompanied massive databases, large numbers of Raman spectra require to be handled and identified in an effective and automatic manner. This paper proposes an algorithm of material auto-identification, which makes use of machine learning methods to analyze Raman spectra. Firstly, a universal method of spectral feature extraction is designed to automatically process Raman spectra after the background subtraction. Secondly, the extracted feature vectors are used to classify and identify target materials by Adaptive Hypergraph (AH), an efficient classifier in the field of machine learning, in a manner of automation with an accuracy rate of ~99%. Compared with Support Vector Machine (SVM) and Random Forest (RF), two typical methods of classification, the AH classifier provides better performance free of tuning any parameter facing different targets. Thirdly, Cubic Spline Interpolation is introduced to enhance the universal of the proposed algorithm between different databases from different Raman spectrometers with variant vendors. The identification accuracy rate is up to 98% using the high frequency sampling spectra as the learning and the low frequency sampling ones as the testing, respectively. Unlabelled Image • Achieve material auto-identification of Raman spectra using machine learning methods • Design a universal & automatic method of spectral feature extraction for Raman spectra • Classify and identify materials by Adaptive Hypergraph free of parameter manipulating • Introduce Cubic Spline Interpolation to promote the compatibility of Raman database • High accuracy satisfies the requirements of rapid applications in various systems. [ABSTRACT FROM AUTHOR]