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The synthesis of diverse products from the same starting materials is always attractive in organic chemistry. Here, a palladium-catalyzed substrate-controlled regioselective functionalization of unactivated alkenes with trifluoroacetimidoyl chlorides has been developed, which provides a direct but controllable access to a variety of structurally diverse trifluoromethyl-containing indoles and indolines. In more detail, with respect to γ,δ-alkenes, 1,1-geminal difunctionalization of unactivated alkenes with trifluoroacetimidoyl chloride enables the [4 + 1] annulation to produce indoles; as for β,γ-alkenes, a [3 + 2] heteroannulation with the hydrolysis product of trifluoroacetimidoyl chloride through 1,2-vicinal difunctionalization of alkenes occurs to deliver indoline products. The structure of alkene substrates differentiates the regioselectivity of the reaction.

A silver-mediated [3 + 2] cycloaddition of azomethine ylides with trifluoroacetimidoyl chlorides for the rapid assembly of 5-(trifluoromethyl)imidazoles has been developed. Notable features of the reaction include readily accessible reagents, a broad substrate scope, and high efficiency. The protocol can be successfully applied to construct the analogue of the specific allosteric modulator of GABA

Herein, a facile and straightforward route to synthesize 3-trifluoromethyl-1,2,4-triazoles via copper-mediated [3 + 2] cycloaddition of trifluoroacetimidoyl chlorides and N-isocyanoiminotriphenylphosphorane (NIITP) has been described. Mo(CO)6 is utilized as an effective promotor to activate NIITP. The transformation features readily accessible reagents, mild reaction conditions, a broad substrate scope and high efficiency, and could be reproducible on a 3 mmol scale.

A metal-, azide- and CF3-reagent free approach for the synthesis of 5-trifluoromethyl-1,2,3-triazoles via base-mediated cascade annulation of diazo compounds with trifluoroacetimidoyl chlorides has been developed. Notable advantages of the reaction include readily available reagents, mild reaction conditions, a broad substrate scope, high efficiency, and promising synthetic utility. The protocol could be scaled up to the gram scale and be applied to construct the key skeleton of the analogue of LCRF-0004.

Carbonylative reactions by the using of CO surrogates constitute a facile avenue for the assembly of valuable carbonyl-containing compounds due to the colorless, toxic, flammable, and not easy-handing character of carbon monoxide gas. Recent advances in the carbonylative transformations with TFBen (benzene-1,3,5-triyl triformate) as a safe and convenient CO precursor are systematically summarized and discussed, which can be divided into three parts based on the patterns of the obtained products. This Review focuses on the discussion of the application of TFBen in carbonylative synthesis of various carbonyl-containing compounds.

Rocky desertification induced by severe deforestation has caused the water loss and soil erosion in karst regions in southeast China, limiting local social and economic developments. To prevent further rocky desertification, the farmland which had obtained by deforestation were abandoned for recovery. As soil quality improved by agriculture abandonment should be examined, it is necessary to investigate the dynamics of physical and chemical properties of soil in different ages after abandonment. In this study, 38 investigation sites were selected for soil sampling on the slopes in Longtan trough valley in Youyang County, Chongqing Municipality, China. The dominant plant species of the investigation sites were also noted during soil sampling. The sites were divided into seven age classes according to their abandonment time. Dynamics of water content, bulk density, pH, and concentration of available potassium, available phosphorus, available nitrogen, total nitrogen and organic matters were examined. It suggests that soil quality might be deteriorated right after abandonment and then improved from around 20 years after abandonment. Deterioration of soil quality may be induced by lack of plant coverage and exposure of rock outcrops which may accelerate water loss and swelling and shrinkage cycles of soil. After the formation of plant communities and litter layer above the ground, soil quality was then apparently improved. These findings can provide a potential guideline for recovery management in karst regions in southwest of China.

α-Amylase inhibition of chlorogenic acid (CHA) and its component moieties including quinic acid (QA) and caffeic acid (CA) were characterized by IC50, inhibition kinetics, fluorescence quenching, isothermal titration calorimetry, differential scanning calorimetry and molecular docking. QA was found with the highest inhibitory activity in a competitive-mode, and caffeoyl substitution significantly decreased its inhibition but maintained inhibition type. Interestingly, QA hardly quenched α-amylase fluorescence, while CA quenched that significantly without inhibitory activity. This resulted from lack of aromatic ring in QA that can form π-conjugation with α-amylase fluorescent residues. Besides, the binding constant of QA with α-amylase was higher than CHA. Additionally, QA and CA decreased but CHA remained α-amylase thermal stability, indicating that change in α-amylase spatial structure was related with enzyme residue sites involved in interactions with inhibitors, instead of with inhibition effect. Conclusively, caffeoyl substitution decreased α-amylase inhibition of QA through reducing its binding affinity to the enzyme.

A palladium-catalyzed four-component carbonylative cyclization reaction for the expeditious construction of trifluoromethyl-containing trisubstituted imidazoles has been achieved. With readily accessible trifluoroacetimidoyl chlorides, propargyl amines, and diaryliodonium salts as the starting materials, the carbonylative transformation proceeds smoothly under mild conditions to enable the formation of multifunctionalized imidazole molecules in a one-pot, one-step manner. Diaryliodonium salts serve as both oxidants and aryl sources in the reaction.

Traditional methods often only use monaural masking models to decorrelate input signals for stereo acoustic echo cancellation. Whereas, it seems more reasonable to use binaural masking models for the following two reasons. First, stereo signals are heard by two ears rather than just one. Second, psychoacoustic researchers have already shown that there are obvious masking level differences between binaural masking models and monaural masking models. By studying binaural masking level difference models, we first introduce a simplified binaural masking model for stereo acoustic echo cancellation. Considering that the interaural time difference is dominant at low frequencies ( ⩽ 1.5 kHz) and the interaural level difference is a major cue at higher frequencies, we propose to use different signal decorrelation schemes at these two frequency bands. In the low-frequency band, a pitch-driven sinusoidal injection scheme is proposed to maintain the interaural time difference, where the amount of injection is determined by the proposed binaural masking model. In the high-frequency band, a modified sinusoidal phase modulation scheme is applied to make a trade-off between preserving the interaural level difference and decorrelating the stereophonic input signals. Assessment results show that the proposed method can effectively improve the non-unique problem and retain good speech quality.

Since soil and water conservation facilities through the purchase of services by the government, the working procedures had changed. This paper studied the evaluation work program, combination with Yinpan hydropower station, which divided into personnel composition, site survey, data verification, communication and reporting. The legal procedures for the implementation of soil and water conservation were checked to confirm the scope of responsibility for the prevention and control of soil erosion. Spoil yard and stone pit were surveyed and analysed one by one to confirm the soil and water conservation measures, the amount of soil and water conservation measures, the quality evaluation and the effect of soil erosion control. The construction and operation management of soil and water conservation were evaluated in the end. Through soil and water conservation facilities acceptance evaluation of Yinpan Hydropower Station, experience was summarized, which could be used as reference for the acceptance of soil and water conservation facilities in hydropower project in the future.

A t-BuOK-mediated [3 + 2] cycloaddition reaction of trifluoroacetimidoyl chlorides and active methylene isocyanides for the synthesis of 5-trifluoromethyl-imidazoles has been developed. Under mild reaction conditions, the transformation proceeds smoothly in the presence of t-BuOK to afford an array of structurally diverse 5-trifluoromethyl-imidazoles with high efficiency.

In virtually all applications of factor models to aerosol mass apportionment, two important implicit assumptions are made: (a) that the source composition profile matrices remain constant over samples, and (b) that the (diagonal) error covariance matrices are the same from sample to sample. As observed by Gleser [Chemom. Intell. Lab. Syst., 10 (1991) 45] and Currie [Chemom. Intell. Lab. Syst., 10 (1991)], neither of these assumptions is generally true. In this paper, a factor analysis model is presented that accounts for variation over samples of both the source composition profiles and the error covariance matrices. Based on this model, point estimators and confidence set estimators are obtained for the vectors of source contributions using an empirical Bayes approach.

The problem of isomorphisms of attributed relational graphs (IARG) is discussed for pattern analysis. The problem of IARG is formulated into the problem of optimal path search (OPS) of state space. Emphasis is on the proof of the equivalence between IARG and OPS. The direct result of the proof is that relatively concrete form of the function h/sup */(u) is obtained which is the cost of an optimal path from the state u to a goal state. A consistent lower-bounded estimate h(u) of h/sup */(u)P is proposed, and that h(u) has an advantage over h(u) which is a consistent lower-bounded estimate of h/sup */(u) is proved. >

In deviation from the ideal listening environment, multichannel loudspeaker equalization can improve the listening experience. In this paper a multichannel equalization method based on crosstalk cancellation is presented. The basic idea is to estimate the real and desired spatial location or acoustic transfer function for each loudspeaker, and design the equalization filters by a simplified crosstalk cancellation algorithm. The process can be divided into three steps. Firstly, the loudspeakers emit uncorrelated signals simultaneously, while the spatial location and transfer function of each loudspeaker can be measured using a binaural microphone pair. Transfer functions of other desired directions can also be measured by head rotation. Secondly, set the expected loudspeaker configuration, and get the transfer functions between the expected speakers and the listening position utilizing physical model or measuring results from previous step. Finally, the equalization filters are calculated by means of a sim...