Surface weak scratch detection for optical elements based on a multimodal imaging system and a deep encoder-decoder network.

The detection of surface weak scratches is an intractable but vital task in optics-centered industries. However, the intrinsic characteristics of weak scratches, such as a narrow width, long span, and shallow depth, make it extremely difficult to effectively detect these scratches. In this paper, we tackle this issue from two perspectives. First, a multimodal microscopic imaging system is created by combining discrete multispectral illumination with linear polarization. Imaging experiments demonstrated that this system could highlight more scratch details, improve image clarity, and alleviate the image blur problem induced by wide spectrum scattered lights. Second, a scratch-oriented U-shaped deep encoder-decoder network equipped with optimized residual encoding modules, serial-parallel multiscale fusion modules, and triple-convolution decoding modules is proposed to segment the weak scratches from a raw image. The detection experiments demonstrate that our model can accurately segment the weak scratches on optical surfaces and achieve better detection performance using significantly fewer parameters compared to similar deep learning models. Meanwhile, experiments on the building crack dataset prove the excellent generalization capability.

Preparation of Nanocellulose-Based Aerogel and Its Research Progress in Wastewater Treatment.

Nowadays, the fast expansion of the economy and industry results in a considerable volume of wastewater being released, severely affecting water quality and the environment. It has a significant influence on the biological environment, both terrestrial and aquatic plant and animal life, and human health. Therefore, wastewater treatment is a global issue of great concern. Nanocellulose's hydrophilicity, easy surface modification, rich functional groups, and biocompatibility make it a candidate material for the preparation of aerogels. The third generation of aerogel is a nanocellulose-based aerogel. It has unique advantages such as a high specific surface area, a three-dimensional structure, is biodegradable, has a low density, has high porosity, and is renewable. It has the opportunity to replace traditional adsorbents (activated carbon, activated zeolite, etc.). This paper reviews the fabrication of nanocellulose-based aerogels. The preparation process is divided into four main steps: the preparation of nanocellulose, gelation of nanocellulose, solvent replacement of nanocellulose wet gel, and drying of nanocellulose wet aerogel. Furthermore, the research progress of the application of nanocellulose-based aerogels in the adsorption of dyes, heavy metal ions, antibiotics, organic solvents, and oil-water separation is reviewed. Finally, the development prospects and future challenges of nanocellulose-based aerogels are discussed.

A Chitosan-Based Fluorescent Probe Combined with Smartphone Technology for the Detection of Hypochlorite in Pure Water.

Using chitosan as a raw material, 1,8-naphthimide as the fluorescent chromophore, and sulfur-containing compounds as the recognition groups, a novel naphthimide-functionalized chitosan probe, CS-BNS, for the detection of ClO- was successfully synthesized. The modification of chitosan was verified by SEM, XRD, FTIR, mapping, 13C-NMR, TG and the structure of the probe molecule was characterized. The identification performance of the probes was studied using UV and fluorescence spectrophotometers. The results show that CS-BNS exhibits a specific response to ClO- based on the oxidative reaction of ClO- to the recognition motifs, as well as a good resistance to interference. And the probe has high sensitivity and fast response time, and can complete the detection of ClO- in a pure water system within 60 s. The probe can also quantify ClO- (y = 30.698x + 532.37, R2 = 0.9833) with a detection limit as low as 0.27 µM. In addition, the combination of the probe with smartphone technology enables the visualization and real-time monitoring of ClO-. Moreover, an identification system for ClO- was established by combining the probe with smartphone technology, which realized the visualization and real-time monitoring of ClO-.

Palladium-Catalyzed Preparation of N-Substituted Benz[c,d]indol-2-imines and N-Substituted Amino-1-naphthylamides.

Here, we report a novel and facile protocol for the synthesis of benz[c,d]indol-2-imines via palladium-catalyzed C-C and C-N coupling of 8-halo-1-naphthylamines with isocyanides in a single step. The reaction features broad substrate scopes and mild conditions, providing an efficient alternative for the construction of antiproliferative agents and BET bromodomain inhibitors. If 0.1 mL of H2O was added to this reaction, the N-substituted amino-1-naphthylamides could be obtained easily.

Copper-catalyzed construction of (Z)-benzo[cd]indoles: stereoselective intramolecular trans-addition and SN-Ar reaction.

Substituted benzo[cd]indoles are one of the most attractive frameworks because of their wide range of biological and optical activities. Herein, a copper-catalyzed one-step synthesis of biologically important polysubstituted benzo[cd]indoles starting from 8-alkynyl-1-naphthylamine derivatives is reported. In this protocol, many substituents tolerated the reaction conditions and produced (Z)-benzo[cd]indoles in good yields. Preliminary mechanistic studies indicated that the reaction proceeds via a stereoselective intramolecular trans-addition and SN-Ar reaction with high selectivity and high yields. The synthesized polysubstituted (Z)-benzo[cd]indoles possess sulfonamide building blocks, which make them candidates for bioactive molecules.

The copper-catalyzed synthesis of (Z)-2H-naphtho[1,8-bc]thiophenes with solid emission.

In recent years, one of the main research interests of our group has been the construction of 6/5 π-systems through the regioselective conversion of parallel alkynes in naphthalene with the aim of exploiting potential fluorescent materials. Herein, the copper-catalyzed synthesis of polysubstituted (Z)-2H-naphtho[1,8-bc]thiophenes from 8-halo-1-ethynylnaphthalenes using potassium ethylxanthate as the sulfur source is reported. In this protocol, a series of thiophene-fused 6/5 π-system compounds was synthesized via copper-catalyzed Ullmann-type C(aryl)-S bond formation and the α-addition of an alkyne bond with high selectivity and in high yields. The synthesized polysubstituted (Z)-2H-naphtho[1,8-bc]thiophenes exhibited solid emission, which made them potential candidates for use in optoelectronic conjugated materials. By using DMSO/D2O (3 : 1) as the reaction solvent, the deuterated products could be obtained in good yields under standard conditions.

Insights into spatiotemporal variations of the water quality in Taihu Lake Basin, China.

Taihu Lake Basin is highly developed but suffers from perennial water shortages due to pollution. Most studies have been limited to examining the water quality in specific areas, but few have investigated the entire basin. This study was based on official water quality data obtained from 565 sites in the monitoring network, thereby covering the entire basin. The water quality spatiotemporal variations were explored by statistical analysis, and the precise spatial distribution of the main pollutants was analyzed by heat maps. Only 29.09% of the water quality assessment results showed "drinkable," whereas 28.63% showed "moderate" and "severe" pollution. The "severe" proportion had a significant declining trend (R2 = 0.933) and was affected by the variations of nitrogen that was related to rainfall and anthropogenic activities. The water quality spatial variation was most likely related to anthropogenic influence and land use. The water quality in the developed and densely populated urban areas was poor, especially in downtown Shanghai. NH3-N, TN, TP, BOD5, COD, CODMn, and DO were the main pollutants that affected the water quality. NH3-N and TN were major reduction targets. NH3-N was the main pollutant that deteriorated the water quality in most densely populated urban areas. Many lakes and reservoirs were highly polluted with TN. Controlling domestic sewage may be effective to improve the water quality. This study makes up for the limited research on the water quality spatiotemporal variations in the entire Taihu Lake Basin and provides beneficial information and suggestions for decision-making regarding the water management.

Copper-Catalyzed Tandem Radical Cyclization of 8-Ethynyl-1-naphthyl-amines for the Synthesis of 2H-Benzo[e][1,2]thiazine 1,1-Dioxides and its Fluorescence Properties.

A copper-catalyzed radical cascade dehydrogenative cyclization of N-tosyl-8-ethynyl-1-naphthylamines under air is described herein for the synthesis of thioazafluoranthenes. The reaction proceeds smoothly with high efficiency and a broad reaction scope. The product is indeed a new fluorophore and its photophysical properties are also investigated. Based on the results, we are pleased to find that the Stokes shift of amino-linked thioazafluoranthenes in dilute tetrahydrofuran is determined to be 143 nm (4830 cm-1).

Copper-Catalyzed Preparation of Benzo[3,4]indolo[1,2-b]isoquinoline-8-ones and Photoluminescence Exploration.

A facile synthesis of benzo[3,4]indolo[1,2-b]isoquinolin-8-ones is described. Under copper catalysis, the reaction proceeds with a high efficiency and a broad reaction scope. A deuteration experiment shows that the KIE value is 2.85. From the results on mechanism studies, copper-catalyzed C-H activation, intramolecular cis-addition of alkynes, and reductive elimination are involved. Moreover, this skeleton is indeed a new fluorophore, and its photophysical properties are also investigated.

Silver-Catalyzed Stereoselective Cyclization to Polysubstituted ( Z)-1,2-Dihydrobenzo[ cd]indoles.

Silver-catalyzed stereoselective synthesis of polysubstituted ( Z)-1,2-dihydrobenzo[ cd]indoles from 8-ethynylnaphthalen-1-amines is reported. In this protocol, a series of nitrogen-containing heterocyclic compounds were synthesized by silver-catalyzed α-addition of an alkyne bond with high selectivity and high yields. The synthesized polysubstituted 1,2-dihydrobenzo[ cd]indoles could be easily converted to benzo[ cd]indol-2(1 H)-ones, and both 1,2-dihydrobenzo[ cd]indoles and benzo[ cd]indol- 2(1 H)-ones are biological and pharmaceutical cores.

Stereoselective and regioselective 5-exo-dig cyclization of 8-alkynylnaphthalen-1-amines for the synthesis of (E)-2-(arylthio)alkylene-1,2-dihydrobenzo[cd]indoles.

A palladium and iodine-cocatalyzed 5-exo-dig aza-thiocyclization of 8-alkynylnaphthalen-1-amines for the synthesis of (E)-2-alkylene-1,2-dihydrobenzo[cd]indole thioethers is reported. As a result of broad reaction scope, simple operation, mild conditions, and high stereoselectivity and regioselectivity, this reaction should have potential utility in organic synthesis.

Construction of Polysubstituted 1,2-Dihydrocyclobuta[b]naphthalenes and 1,2-Dihydrocyclobuta[b]anthracenes with Photoluminescence.

A facile protocol for the synthesis of polysubstituted 1,2-dihydrocyclobuta[b]naphthalenes and 1,2-dihydrocyclobuta[b]anthracenes was developed via a sequence of base-promoted 1,5-H shift, intramolecular [2 + 2] cycloaddition, and aromatization. The synthesized 1,2-dihydrocyclobuta[b]anthracenes exhibited bright blue emissions in solution and strong yellow emissions in solid, which made them possible candidates for optoelectronic conjugated materials.

Synthesis of benzil-o-carboxylate derivatives and isocoumarins through neighboring ester-participating bromocyclizations of o-alkynylbenzoates.

Bromide mediated neighboring ester-participating bromocyclizations of o-alkynylbenzoates are described here for the synthesis of benzil-o-carboxylates. 4-bromoisocoumarins are also synthesized when phenyl o-alkynylbenzoate is used as the substrate. Mechanistic studies suggest that the whole process is composed of an electrophilic bromocyclization and a dibromohydration-based ring-opening, and the neighboring ester group participates in the bromocyclization. Interestingly, the two oxygen atoms of the keto carbonyls in benzil-o-carboxylates are both derived from water. The electrophilic bromo source is in situ generated from the oxidation of bromide.

Analysis of the spatial-temporal variation characteristics of vegetative drought and its relationship with meteorological factors in China from 1982 to 2010.

Drought is a complex natural phenomenon that can cause reduced water supplies and can consequently have substantial effects on agriculture and socioeconomic activities. The objective of this study was to gain a better understanding of the spatial-temporal variation characteristics of vegetative drought and its relationship with meteorological factors in China. The Vegetation Condition Index (VCI) dataset calculated from NOAA/AVHRR images from 1982 to 2010 was used to analyse the spatial-temporal variation characteristics of vegetative drought in China. This study also examined the trends in meteorological factors and their influences on drought using monitoring data collected from 686 national ground meteorological stations. The results showed that the VCI appeared to slowly rise in China from 1982 to 2010. From 1982 to 1999, the VCI rose slowly. Then, around 2000, the VCI exhibited a severe fluctuation before it entered into a relatively stable stage. Drought frequencies in China were higher, showing a spatial distribution feature of "higher in the north and lower in the south". Based on the different levels of drought, the frequencies of mild and moderate drought in four geographical areas were higher, and the frequency of severe drought was higher only in ecologically vulnerable areas, such as the Tarim Basin and the Qaidam Basin. Drought was mainly influenced by meteorological factors, which differed regionally. In the northern region, the main influential factor was sunshine duration, while the other factors showed minimal effects. In the southern region and Tibetan Plateau, the main influential factors were sunshine duration and temperature. In the northwestern region, the main influential factors were wind velocity and station atmospheric pressure.

Synthesis of benzothiophene and indole derivatives through metal-free propargyl-allene rearrangement and allyl migration.

An efficient base-catalyzed protocol for the synthesis of benzothiophene is described. The reaction proceeds via base-promoted propargyl-allenyl rearrangement followed by cyclization and allyl migration. Phosphine-substituted indoles can be synthesized by a similar strategy.

Correction: Copper-mediated cyanation of indoles and electron-rich arenes using DMF as a single surrogate.

Correction for 'Copper-mediated cyanation of indoles and electron-rich arenes using DMF as a single surrogate' by Lianpeng Zhang et al., Org. Biomol. Chem., 2015, 13, 8322-8329.

Drought trends based on the VCI and its correlation with climate factors in the agricultural areas of China from 1982 to 2010.

Drought is a type of natural disaster that has the most significant impacts on agriculture. Regional drought monitoring based on remote sensing has become popular due to the development of remote sensing technology. In this study, vegetation condition index (VCI) data recorded from 1982 to 2010 in agricultural areas of China were obtained from advanced very high resolution radiometer (AVHRR) data, and the temporal and spatial variations in each drought were analyzed. The relationships between drought and climate factors were also analyzed. The results showed that from 1982 to 2010, the agricultural areas that experienced frequent and severe droughts were mainly concentrated in the northwestern areas and Huang-Huai Plain. Moreover, the VCI increased in the majority of agricultural areas, indicating that the drought frequency decreased over time, and the decreasing trend in the southern region was more notable than that in the northern region. A correlation analysis showed that temperature and wind velocity were the main factors that influenced drought in the agricultural areas of China. From a regional perspective, excluding precipitation, the climate factors had various effects on drought in different regions. However, the correlation between the VCI and precipitation was low, possibly due to the widespread use of artificial irrigation technology, which reduces the reliance of agricultural areas on precipitation.

Copper-mediated cyanation of indoles and electron-rich arenes using DMF as a single surrogate.

The copper-mediated cyanation of indoles with DMF as a single surrogate has been realized. This approach could be applied for the cyanation of some electron-rich arenes and aryl aldehydes as well. Aryl aldehydes were demonstrated to be the key intermediates in the cascade process of cyanation of indoles and electron-rich arenes.

Electrospun microcrystalline cellulose/chitosan porous composite nanofibrous membranes modified by non-thermal plasma for gaseous formaldehyde adsorption.

To develop a green and facile adsorbent for removing indoor polluted formaldehyde (HCHO) gas, the biomass porous nanofibrous membranes (BPNMs) derived from microcrystalline cellulose/chitosan were fabricated by electrospinning. The enhanced chemical adsorption sites with diverse oxygen (O) and nitrogen (N)-containing functional groups were introduced on the surface of BPNMs by non-thermal plasma modification under carbon dioxide (CO2) and nitrogen (N2) atmospheres. The average nanofiber diameters of nanofibrous membranes and their nanomechanical elastic modulus and hardness values decreased from 341 nm to 175-317 nm and from 2.00 GPa and 0.25 GPa to 1.70 GPa and 0.21 GPa, respectively, after plasma activation. The plasma-activated nanofibers showed superior hydrophilicity (WCA = 0°) and higher crystallinity than that of the control. The optimal HCHO adsorption capacity (134.16 mg g-1) of BPNMs was achieved under a N2 atmosphere at a plasma power of 30 W and for 3 min, which was 62.42 % higher compared with the control. Pyrrolic N, pyridinic N, CO and O-C=O were the most significant O and N-containing functional groups for the improved chemical adsorption of the BPNMs. The adsorption mechanism involved a synergistic combination of physical and chemical adsorption. This study provides a novel strategy that combines clean plasma activation with electrospinning to efficiently remove gaseous HCHO.

Synthesis and application of hypochlorite ratiometric fluorescence probe based on cellulose.

Cellulose is the most abundant natural polymer with good biocompatibility and easy modification characteristics. In this paper, a novel cellulose fluorescence probe CNS for detecting ClO- was prepared by modifying microcrystalline cellulose (MCC). The fluorescence detection results indicate that CNS exhibits a highly specific "ratiometric" and "colorimetric" fluorescence response to ClO-. In the presence of ClO-, the fluorescence color changes from green to cyan. In addition, the color of the solution changes from yellow to colorless, which can be observed with the "naked eye". Considering the good selectivity and anti-interference ability of CNS, the probe can be used for the detection of ClO- in real water samples. Importantly, CNS composite films and test papers were prepared and showed practicability in the detection of ClO-, highlighting its broad application potentials.