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Online shopping evaluation is one of the important decisions for consumers to do online shopping. The negative comments in the evaluation have an important impact on consumers in shopping. Based on the product classification theory, this paper classifies the products consumers mainly buy on online shopping platforms into five major categories: daily necessities, educational and sporting goods, home appliances and digital products, food, and clothing accessories, and serves as a moderating factor. The hypothesis is that the number of negative reviews about logistics and transportation would negatively affect consumers’ willingness to purchase daily necessities and food. The number of bad reviews about merchants’ services would negatively affect consumers’ purchase intention for apparel accessories. The number of bad reviews about products that would negatively affect consumers’ willingness to purchase digital home appliances and educational and sporting goods online was proposed. A questionnaire was used to obtain the sample data of consumers’ online shopping intention, and SPSS was used to test its reliability with different analyses and correlation analyses. Based on the correlation between the content and the number of negative reviews, it showed that six or more negative reviews for food products significantly affect consumers’ willingness to purchase. The number of negative reviews about merchant services for daily necessities and the product for clothing accessories significantly affects consumers’ willingness to purchase. Furthermore, for all types of products, when the number of negative reviews increases, consumers need to increase their willingness to purchase with more positive reviews. Among them, consumers’ occupation, average monthly consumption level, and length of exposure to online shopping moderate the credibility of consumers’ judgment of negative reviews. In conclusion, it is concluded that Taobao merchants should pay attention to the content and quantity in negative reviews, improve the quality of products, services, logistics, and transportation from the consumers’ point of view, and improve the competitiveness of their products for better online marketing.

Hepatitis B virus (HBV) infection is more likely to develop a state of chronicity in early life, particularly mother-to-child transmission (MTCT) of HBV in the fetus during pregnancy. Till now, little is known about the impact of chronic HBV infection on the immune status of the maternal-fetus interface, and the immune profile of placental lymphocytes in MTCT of HBV is poorly understood.Thirteen term pregnant women with chronic HBV infection (HBV-PW) and thirteen normal pregnant women as healthy control (HC-PW) were enrolled. The profile of placental immune cells and paired peripheral blood were analyzed by flow cytometry and immunohistochemistry.Compared with HC-PW, the frequency of CD8These findings supported that hypoactivated decidual CD8

Agostic interactions are examples of σ-type interactions, typically resulting from interactions between C–H σ-bonds with empty transition metal d orbitals. Such interactions often reflect the first step in transition metal-catalysed C–H activation processes and thus are of critical importance in understanding and controlling σ bond activation chemistries. Herein, we report on the unusual electronic structure of linear electron-rich d9 Ni(i) complexes with symmetric bis(C–H) agostic interactions. A combination of Ni K edge and L edge XAS with supporting TD-DFT/DFT calculations reveals an unconventional covalent agostic interaction with limited contributions from the valence Ni 3d orbitals. The agostic interaction is driven via the empty Ni 4p orbitals. The surprisingly strong Ni 4p-derived agostic interaction is dominated by σ contributions with minor π contributions. The resulting ligand–metal donation occurs directly along the C–Ni bond axis, reflecting a novel mode of bis-agostic bonding., Symmetric Ni(i) agostic complexes reveal an unusual mode of bonding that is dominated by direct carbon-to-metal charge transfer.

In today’s rapid development of higher education, the reform of higher applied undergraduate institutions and higher education has become an effective way to improve the quality of higher education personnel training and improved the quality of teaching. With the continuous expansion of the scale of university laboratories, the number of managers is also increasing, but the management of laboratories is still in the exploratory stage. The current laboratory information management system of Internet of Things has high degree of data heterogeneity, poor data interoperability, and difficult guarantee of data privacy, all of which lead to the difficulty in mining the data value of Internet of Things. The decentralized and zero-trust architecture of blockchain subverted the traditional centralized system architecture and has been applied in many aspects. Blockchain technology was a good addition to IOT to improve the privacy security, versatility, and reliability of the network. This thesis developed an IOT information management system for smart labs based on blockchain technology and the Internet of Things. The data processing efficiency, accuracy, and system throughput are compared with the original IOT laboratory information management system. The results showed that compared with the current laboratory IOT information management system, this system had higher speed, higher efficiency, and better performance in processing the information and data.

The electronic nature of Ni π-complexes is underexplored even though these complexes have been widely postulated as intermediates in organometallic chemistry. Herein, the geometric and electronic structure of a series of nickel π-complexes, Ni(dtbpe)(X) (dtbpe=1,2-bis(di-tert-butyl)phosphinoethane; X=alkene or carbonyl containing π-ligands), is probed using a combination of 31 P NMR, Ni K-edge XAS, Ni Kβ XES, and DFT calculations. These complexes are best described as square planar d10 complexes with π-backbonding acting as the dominant contributor to M-L bonding to the π-ligand. The degree of backbonding correlates with 2 JPP from NMR and the energy of the Ni 1s→4pz pre-edge in the Ni K-edge XAS data, and is determined by the energy of the π*ip ligand acceptor orbital. Thus, unactivated olefinic ligands tend to be poor π-acids whereas ketones, aldehydes, and esters allow for greater backbonding. However, backbonding is still significant even in cases in which metal contributions are minor. In such cases, backbonding is dominated by charge donation from the diphosphine, which allows for strong backdonation, although the metal centre retains a formal d10 electronic configuration. This ligand-induced backbonding can be formally described as a 3-centre-4-electron (3c-4e) interaction, in which the nickel centre mediates charge transfer from the phosphine σ-donors to the π*ip ligand acceptor orbital. The implications of this bonding motif are described with respect to both structure and reactivity.

Agostic interactions are examples of σ-type interactions, typically resulting from interactions between C-H σ-bonds with empty transition metal d orbitals. Such interactions often reflect the first step in transition metal-catalysed C-H activation processes and thus are of criticial importance in understanding and controlling σ bond activation chemistries. Herein, we report on the unusual electronic structure of linear electron-rich d9 Ni(I) complexes with symmetric bis(C-H) agostic interactions. A combination of Ni K edge and L edge XAS with supporting TD-DFT/DFT calculations reveals an unconventional covalent agostic interaction with limited contributions from the valence Ni 3d orbitals. The agostic interaction is driven via the empty Ni 4p orbitals. The surprisingly strong Ni 4p-derived agostic interaction is dominated by σ contributions with minor π contributions. The resulting ligand-metal donation occurs directly along the C-Ni bond axis, reflecting a novel mode of bis- agostic bonding.

Tetrahydrocannabinol acid (THCA) and cannabidiol acid (CBDA), the two crucial organic components in cannabis and hemp, decarboxylate at different rates to their more active neutral forms. Theoretical calculations are used herein to analyze how the remote annulated ring or pendant substituent influences the rate determining steps of the decarboxylation processes. The uncatalyzed keto-enol tautomerization that precedes decarboxylation is found to be extremely slow in both cases albeit with a ten-fold preference for CBDA. A single molecule of methanol dramatically enhances the reaction rates by allowing for tautomerization through a more favorable six-membered ring transition state. Methanol-catalyzed tautomerization is found to be faster in THCA than in CBDA. This difference results from both the larger dipole moment of the THCA scaffold as well as its greater rigidity relative to CBDA. The greater dipole moment leads to a somewhat better binding of methanol. The lower entropic penalty in THCA towards tautomerization leads to faster decarboxylation.

Herein, metal–ligand bonding features in a chelation N,N′-dioxide–Sc(III) complex have been addressed using the DFT method at the M06/6-31+G** Level. The donor–acceptor interaction between the carbonyl substrate and Sc(III)-based catalyst is analyzed in detail by the activation strain model (ASM), energy decomposition analysis (EDA), and natural orbital for chemical valence (NOCV) calculations. The orbital interaction is the major contributor to N,N′-dioxide–[Sc(OTf)]2+ bonding, whereas the electrostatic interaction plays a more important role than orbital interaction in the activation of a carbonyl compound in hexacoordinate N,N′-dioxide–Sc(III) complexes. The substituents in the amide group of the N,N′-dioxide ligand (L) affect the electrostatic energy as well as the orbital energy between the CH2O and Sc(III)-based catalyst by adjusting the Lewis acidity of the metal centre. The complex with ortho-diisopropylphenyl groups in the ligand exhibits a higher reactivity towards CH2O. Compared to OiPr, the counter ion OTf in the Sc(III)-complex enhances the Lewis acidity of the metal centre and facilitates the activation of CH2O by promoting electron density flow from CH2O to the metal fragment. The high catalytic performance of the N,N′-dioxide–Sc(III) complex towards PhCHO and chalcone is attributed to their good nucleophilicity that results in a more stabilizing electrostatic and orbital interaction between the N,N′-dioxide–[Sc(OTf)]2+ complex and carbonyl substrate.

The electronic nature of Ni π-complexes is underexplored even though these complexes have been widely postulated as intermediates in organometallic chemistry. Herein, the geometric and electronic structure of a series of nickel π-complexes, Ni(dtbpe)(X) (dtbpe=1,2-bis(di-tert-butyl)phosphinoethane; X=alkene or carbonyl containing π-ligands), is probed using a combination of

A series of Ni π-complexes are explored using a combination of spectroscopic and computational methods to reveal an intriguing contribution to backbonding: metal-mediated ligand-to-ligand backdonation. Such ligand-induced backdonation is the dominant contribution for weakly π-acidic ligands such alkenes and allows for strong bonding even though the metal centre retains a formal d10 electronic configuration.

Tetrahydrophthalazine derivatives have found important applications in pharmaceutical research, but existing synthetic methods are unable to access them regio- and stereoselectively. Here, a new approach is presented that addresses these challenges by utilizing a 6-endo-trig radical cyclization in the key step. The desired tetrahydrophthalazines can be accessed in high yields (55-98 %) and high diastereoselectivities for the trans-product (>95:5) starting either from readily accessible hydrazones, or from the corresponding aldehydes and substituted Boc-hydrazides in a one-pot process. The synthetic versatility of the tetrahydrophthalazine core was demonstrated by its straightforward conversion to dihydro-phthalazines, phthalazines, or pyrazolo dione derivatives. Furthermore, the N-N bond was reduced to afford a new route to 1,4-diamines.

Ni π-complexes are widely postulated as intermediates in organometallic chemistry. However, the nature of the bonding in such complexes has not been extensively studied. Herein, we probe the geometric and electronic structure of a series of nickel π-complexes using a combination of 31P NMR, Ni K-edge XAS, Ni Kβ XES, and supporting density-functional computations. These complexes are best described as square planar d10 complexes with π-backbonding acting as the dominant factor in the M-L bond to the π ligand. The degree of backbonding correlates with both 2JPP and the energy of the clearly observable Ni 1s→4pz pre-edge transition in the Ni K-edge XAS data. The degree of backbonding is determined by the energy of the π*ip ligand acceptor orbital: unactivated olefinic ligands tend to be poor π-acids whereas ketones, aldehydes, and esters allow for greater backbonding. The strength of the backbonding from the neutral Ni(dtbpe) molecular fragment is dramatically increased via σ donation from the diphosphine ligands. In fact, in unactivated pi complexes, backbonding is dominated by charge donation from the phosphines, which allows for strong backdonation even though the metal centre retains a formal d10 electronic configuration. We describe this interaction as a formal 3-centre-4-electron (3c-4e) interaction where the nickel centre mediates charge transfer from the phosphine σ-donors to the π*ip ligand acceptor orbital. The implications of this unusual bonding motif are described with respect to both geometric structure and reactivity.

We have structurally characterized a nickel(0) thiophene complex that represents a close analog to the proposed intermediates in the mechanism of catalyst transfer polycondensation (CTP) of thiophenes. Additional studies on this intermediate allow us to determine the bonding in such complexes using a combination of nuclear magnetic resonance spectroscopy, X-ray absorption spectroscopy, and DFT-based computations. Our structure of the catalyst agrees with previous postulates but provides important new structural insights into the species. Furthermore, our studies explain why these complexes actually exist and are stable enough to support living CTP.