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Over a full molar fraction range, for binary mixtures of x N-methylimidazole (hereafter abbreviated to N-mim) + (1 − x) water, +methanol, +ethanol, +1-propanol, +2-propanol, the mass density and sound velocity at (288.15, 298.15, 308.15, 318.15, 328.15) K, the mixing enthalpy at 298.15 K, and 1H NMR measurements, combined with the Ab initio calculations, have been carried out. The excess molar volume, excess average volume expansivity, excess sound velocity, excess isentropic compressibility, and the molar mixing enthalpy were calculated and fitted to a Redlich-Kister equation. The partial molar enthalpy of N-mim, the difference between the partial molar volume and the molar volume of N-mim, and the protons chemical shift changes were calculated and compared. The chemical shifts of N-mim protons, hydroxyl protons, and α-H (proton on the carbon atom next to the –OH group) of alcohols in the mixtures containing alcohols were explained by a model proposed by Gupta et al.. The properties indicate that the intermolecular interactions between unlike molecules are stronger than those between like molecules. An increase in temperature has a greater influence on the mixture containing water than on pure components, and has a greater influence on pure components than on mixtures containing alcohols. The predominant interactions between unlike molecules are hydrogen-bonded complexes in the mixture containing water, and are N-mim: alcohols = 1:1 hydrogen-bonded networks in the mixtures containing alcohols, where the alkyl groups of alcohols are electron-withdrawing groups, and the methyl group of N-mim is an electron-donating group. Ab initio calculations proved that the N⋯HO hydrogen bond in the mixtures is more stable and stronger than HO⋯HO in pure water or in pure alcohols and N⋯HC in pure N-mim. The strength sequence of the intermolecular interactions between unlike molecules for the mixtures at 298.15 K is N-mim–water > N-mim–methanol > N-mim–ethanol > N-mim–1-propanol ≥ N-mim–2-propanol.

For a binary mixture of x N-methylimidazole (hereafter abbreviated as N-mim) + (1 − x) ethyl acetate (hereafter abbreviated as EAC), the density, sound velocity, viscosity and refractive index at (288.15, 298.15, 308.15, 318.15, and 328.15) K, mixing enthalpy at 298.15 K, and 1H NMR measurements combined with the ab initio calculations were carried out over a full molar fraction range. The density, sound velocity, isentropic compressibility, refractive index, viscosity, Gibbs energy of activation of viscous flow and the isobaric thermal expansivity were correlated with a polynomial well. The excess molar volume, excess isobaric thermal expansivity, isobaric thermal expansivity deviation, excess sound velocity, sound velocity deviation, excess isentropic compressibility, isentropic compressibility deviation, excess refractive index, refractive index deviation, excess logarithm viscosity, viscosity deviation, excess Gibbs energy of activation of viscous flow and the molar mixing enthalpy, were calculated and fitted to a Redlich-Kister polynomial. The activation parameters of viscous flow of the mixture, chemical shift changes of N-mim and EAC protons, interaction energy and second-order perturbation stabilization energy of 2-CH···O C, 2-CH···N and CH···O H-bonds were calculated. The mixing process of N-mim with EAC is an endothermic process with volume contraction. The energy to break the like molecular interactions is bigger than that to form dislike molecular interactions, and the volume contraction is mainly attributed to both the free volume difference and the more effective steric accommodation of molecules in the mixture. The 2-CH···O C and 2-CH···N H-bonds are approximately equivalent in dimers, 2-CH···O C H-bond in dimer (N-mim + EAC) is stronger and more stable than the CH···O H-bonds in EAC dimer. The amount of 2-CH···O C H-bond reaches a zenith at x ≈ 0.5. The formation of 2-CH···O C H-bond leads to the electron density rearrangement of the N-mim and EAC molecules, where the electron densities of the N-mim and EAC protons decrease and increase, respectively.

Previous study shows that HBT-based fluorophore HBT-Ratio-F1 and F2 are excellent sensor with selectivity and sensitivity towards F anion showing binate ratiometric characteristics. In this work, we study the whole sensing process by DFT and TDDFT methods in detail. The electronic structures and electronic characters of the neutral sensor, F anion attached complex, and anionic form after deprotonation are investigated in both S0 and S1 states. In neutral sensor, the potential energy profile of proton transfer is investigated to understand the tautomerization process. In anion, the cis-trans isomerization process is also investigated in both S0 and S1 states to unveil the behavior of anion. The calculated results show that intra molecular hydrogen bond O H⋯ N in neutral sensor is disturbed upon addition of F anion, forming new inter molecular hydrogen bond (O)N⋯ H F in the (S0) S1 state in anion complex and HF is likely to be bonded with HBT derivative without further dissociation. The comparison of the calculated absorption (emission) energies in both HBT-Ratio-F1 and HBT-Ratio-F2 with experimental spectral peaks is also included and the binate ratiometric character in spectra is discussed based on calculation results.

Developing high performance fluorescent chemo-sensors for in vitro and in vivo Al3+ detection is highly desirable, because Al3+ accumulation has been involved to various diseases. Herein, we report a highly selective and sensitive Schiff base fluorescent probe, H3L, based on 2-hydroxynaphthalene, which can recognize aluminum ions and exhibit an “off-on” mode with high selectivity in methanol solutions. The detection limit of the probe for Al3+ is as low as 10−7 M which was determined by fluorescent titration. The high selectivity and high sensitivity of H3L for Al3+ are attributed to the inhibition of ESIPT. Additionally, the distribution of intracellular Al3+ ions could be observed under confocal fluorescence microscopy. Moreover, we also applied H3L for in vivo detection of Al3+ ions in living zebrafish larvae.

Based on the density functional theory (DFT) level, the thermal reaction of PtOH+ with methane has been investigated theoretically using the empirically parametrized hybrid functional B3LYP. The favorable path for the reaction of PtOH+ + CH4 is the channel of the elimination of H2O. The overall reaction is exothermic by 16.5 kcal/mol. The NBO analysis demonstrated that the ligand effect resulting in the electronic occupies in the quasi-restricted orbitals and also shows a proton-coupled electron transfer component in 3TS2-H2O. By comparing among the reactions of Pt+, [Pt(H)(OH)]+ and PtOH+ with CH4, PtOH+ is more reactive to methane than Pt+ and [Pt(H)(OH)]+ thermodynamically. These results can not only deepen the understanding of the mechanism, but also guide the reasonable design of catalysts.

The complexes between BH(CO)2/BH(N2)2 and XF3/XF5 are stabilized by a halogen bond and a triel bond. The MEP analyses of BH(CO)2/BH(N2)2 indicate that there are both a region with negative MEPs on the B atom in the vertical direction of the molecular plane and a σ-hole at the B-H bond end. Therefore, the boron atom in BH(CO)2/BH(N2)2 plays a dual role of a Lewis base and an acid in the halogen bond and triel bond, respectively. The halogen and triel bonds are stronger in order of IF3

For a binary mixture of xN-methylimidazole (hereafter abbreviated to N-mim) + (1-x) water, over a full molar fraction range, the mass density, sound velocity, refractive index, viscosity, mixing enthalpy, conductivity, and pH at (298.15, 308.15, 318.15) K and 0.1 MPa, and 1H NMR and 13C NMR at room temperature combined with Ab initio calculations, were measured and carried out. The excess molar volume (VmE), sound deviation (∆u), refractive index deviation (∆nD), viscosity deviation (∆η), excess Gibbs energy of activation of viscous flow (∆G⁎E), molar mixing enthalpy (∆mixHm), 1H NMR chemical shift changes of N-mim and water protons (∆δH), 13C NMR chemical shift change of N-mim (∆δC), sum of the chemical shift changes (∑∆δH(N-mim), ∑∆δC), and the interaction energy, hydrogen bond length, second-order perturbation stabilization energy, electron density, and the electronic energy density of the trimer hydrogen-bonded complexes were calculated. The values of VmE, ∆u, ∆nD, ∆η, ∆G⁎E, and ∆mixHm were fitted to a Redlich-Kister equation. The extreme positions of these quantities and the chemical shift changes were compared and discussed with regard to the intermolecular interaction between N-mim and water, and a possible molecular interaction scheme was suggested for N-mim added to water. There occurs an ionization process and hydrogen-bonded interactions between N-mim and water. The ionization process may not be neglected at an infinite dilution of water, and hydrogen bonds predominate the primary interaction in the mixture. The predominant hydrogen-bonded complex in the mixture transforms with increasing x, which is consistent with the calculation results.

With the development of information technology, the importance of big data is quickly highlighted. Big data applications show great value to individuals, companies and governments. Recently, researches on the storage and utilization of big data have achieved considerable results. The prosperity of big data applications is a thrust of drawing attention to the system performance such as timeliness, computational and communication resources. Data retransmission caused by the violation of the stringent delay bound may result in the reprocessing of these data, which would have a negative effect on user experience. To fill this gap, a software defined architecture is developed in this work so that the appropriate start point of processing can be found for the data need to be reprocessed. For further improvement of the processing performance, two models are presented to this software defined architecture. In the optimized model, a priority queue is employed to facilitate the processing efficiency. In addition, data flows transmitting through networks exhibit obvious self-similar characteristics. Performance analysis without taking traffic self-similarity into account may lead to unexpected results. In the optimized model, the tightly coupled system makes performance analysis difficult. Therefore, a decomposition approach is employed to divide the coupled system into a group of single server single queue systems. Finally, the developed model is validated through extensive experimental results.

A new aluminum ion fluorescent probe (4-(diethylamino)-2-hydroxybenzylidene)isoquinoline-1-carbohydrazide (HL1) has been conveniently synthesized and characterized. HL1 exhibited a highly selective and pronounced enhancement for Al3+ in the fluorescence emission over other common cations by forming a 2:1 complex, with a recognition mechanism based on excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT). The strong fluorescent emission can be observed even at ppm level concentration of the probe in the presence of Al3+ with 41 fold intensity enhancement at 545 nm. HL1 displays good linear relationship with Al3+ in the low concentration and the limit of detection is 8.08 × 10-8 mol/L. Similar molecules with different substituents on salicylaldehyde phenyl ring were synthesized for studying the structure-activity relationship. Density-functional theory (DFT) calculations are in agreement with the proposed mechanism. It is confirmed that HL1 could be used to detect Al3+ ions in real sample by fluorescence spectrometry and Al3+ ions in cells by bioimaging.

An ab initio calculation has been performed for the complexes of F2C CFTF3 (T C, Si, and Ge) with three Lewis bases including H2CO, H2O, and NH3. Most complexes are stabilized by tetrel bonds together with weak hydrogen bonds. The Lewis bases can be introduced to the σ-hole and π-hole of F2C CFTF3, but the σ-hole bonded complexes are preferential for F2C CFTF3 (T Si and Ge), while the π-hole bonded complexes are favorable for F2C CFCF3. Hybridization of the carbon atom adjoined with the SiF3 group strengthens the σ-hole tetrel bond in the order sp3

The photophysical properties as well as proton transfer process from normal form (Enol) to tautomer form (Keto) in 1,8-Dihydroxydibenzo[a,h]phenazine [DHBP] have been theoretically investigated by TDDFT method. The potential energy profiles of the reaction paths for concerted proton transfer and stepwise proton transfer via single-proton transferred intermediate (INT) are examined, and the results show that proton transfer occurs in locally excited state following the stepwise mechanism at the lowest excitation energy in the gas phase. The concerted reaction path is found to be unstable with respect to anti-symmetric mode statically. The steady state emission band detected in Piechowska et al. experiment was assigned to INT, while emissions from Enol and Keto are less likely to be observed. The low intensity of the fluorescence at INT can be explained by the inter-system crossing between the lowest singlet state S1 with the triplet states T1 and T2 instead of the internal conversion from S1 to S0 introduced by torsion at INT structure at current computational level. This study provides new insight into the quenching mechanism in π-extended rigid molecule DHBP.

An increasing number of physical assets, such as academic certificates and credentials, are being represented in the form of digital assets. These assets always involve multiple statuses, rules, and complex associations. It is challenging to determine the transaction execution order using the existing blockchains because they lack the ability to record and execute associations between assets, which results in problems of inconsistency of assets, such as the loss of asset status changes and status conflict between transactions. This study proposes a blockchain-native mechanism supporting complex physical assets, including a novel digital asset model and transaction validity guarantee protocol. Under the premise of ensuring safety and performance, the proposed mechanism can fully describe different associations and their influence on the transaction execution order. This study builds a global deterministic transaction execution sequence that can be executed in parallel to guarantee the consistency of complex digital assets based on partial orders. Theoretical analysis of the proposed mechanism demonstrates that it can guarantee digital asset consistency and can protect against attacks such as reentrant and transaction sequence attacks. Furthermore, experiments show that the proposed mechanism can achieve a transaction execution speed of up to 10,000 transactions per second, and this speed can be further increased by increasing the number of CPU cores.

The discrimination and identification of human serum albumin (HSA) and bovine serum albumin (BSA) is very important, which is due to the vital roles of two SAs in biological and pharmaceutical research. Based on structural screening and docking calculation from a series of homologues, a coumarin Schiff base fluorescent probe 3-hydroxy-N′-((4-oxo-4H-chromen-3-yl)methylene)-2-naphthohydrazide (HCNH) has been designed and synthesized, which could effectively discriminate HSA and BSA. The probe HCNH exhibited superior sensitivity toward HSA and BSA with the detection limits of 10.62 nM and 16.03 nM in PBS solution, respectively. The binding mechanism of HCNH with SAs was studied by Job’s plot analysis, SA destruction and displacement assay. Molecular docking and DFT methods were utilized to provide deep insight into the spatial conformation change of HCNH and binding sites in HSA/BSA. The conformation of HCNH was significantly influenced by the microenvironment provided by HSA and BSA, therefore its fluorescence emission was affected correspondingly. Non-toxic probe HCNH could be successfully used for fluorescence bio-imaging of HSA in cancer cells, which is significantly different from normal cells and favors the application in medical diagnosis.

Numerous Prussian blue analogues (PBAs) and their application in cesium elimination have been conducted. However, those were practically impossible to use in alkaline solution and seawater, due to the low stabilization of PBAs in alkaline solution and quickly decompose to create toxic cyanide contamination. In this research, potassium zinc hexacyanoferrate (PZH), one kind of PBAs was chosen, and the stability of PZH in the alkaline solution was remedied by incorporating magnetic rectorite (MR) and evaluated by XRD, XPS and cyanide analysis. Effect of pH value and the water systems on the crystalline and chemical stability were studied. The adsorption performance for Cs+ in high pH solution and the biological toxicity of the PZH/MR composite were also evaluated. The composite material exhibits significant adsorption capacity for Cs+ ions (215.128 mg/g, 293 K, increased over 20% than pristine PZH) and low cytotoxicity in human hepatic cells (HepG2 cells), indicating its potential application Cs+ adsorption in waste-water and Cs+ decorporation from body. The stability and safety mechanism in a wide pH range (from 2 to 11) were explained. The stabilization method on PBAs is an advanced yet and effective feasible mean with applications for internal and external cesium remediation. This research opens up a wide range of novel applications for PB-based adsorbents or decorporation, particularly in the field of the cesium remediation in high pH value.

The metal cations, Al3+ and Mg2+, could affect human health and cell biological processes. Their fast and selective detection using one probe remains a challenge. A novel fluorescence probe, N'-((1-hydroxynaphthalen-2-yl)methylene)isoquinoline-3-carbohydrazide (NHMI), was developed for selectively monitoring Al3+ and Mg2+. The probe NHMI showed a distinctive “turn-on” fluorescence signal towards Al3+ and Mg2+ (cyan for Al3+ with 2556-folds enhancement and yellow for Mg2+ with 88-folds enhancement), which is quite distinct from other metal cations and allows for naked-eye detection. This interesting response was attributed to the influence of PET, ESIPT process and CHEF effect, when Al3+ or Mg2+ chelated with NHMI. Furthermore, the fluorescence titration experiments manifested that the detection limit of probe NHMI for Al3+/Mg2+ was as low as 1.20 × 10–8 M and 7.69 × 10–8 M, respectively. The formed complexes NHMI-Al3+ and NHMI-Mg2+ were analyzed by Job's plot, ESI-MS, 1H NMR and FT-IR. The coordination pockets and fluorescence mechanisms of two metal complexes were explored by density functional theory calculation. Moreover, NHMI showed low cytotoxicity and good cell permeability. Fluorescence bioimaging of Al3+/Mg2+ in MCF-7 cells with NHMI indicated its potential application in biological diagnostic analysis.

A new underwater video compression technique based on adaptive hybrid wavelets and directional filter banks is proposed to achieve both high coding efficiency and good reconstruction quality at very low-bit rates. A key application is the real-time transmission of video through acoustic channels with limited bandwidth, from an autonomous underwater vehicle to a surface station, e.g., for man-in-the-loop monitoring and inspection operations. For intra-frame coding, the method maintains details in texture regions at relatively low bit rates, and overcomes the ringing artifacts within smooth regions. For inter-frame coding, improved efficiency is achieved by making use of: (1) a new spatio-temporal just-noticeable-distortion model to remove perceptual redundancy; (2) motion interpolation to reduce bit rate; and (3) variable-precision in quantizing the residual error. Experiments with underwater video sequences are presented to assess the effectiveness of the proposed approach, in comparison to traditional wavelet-based techniques. HighlightsUnderwater video compression system optimized based on domain image and HVS characteristics.Improved performance over state-of-the-art DWT-based methods.Effective compression of both smooth and textured regions.New spatio-temporal just noticeable distortion (JND) model.Low bit-rate coding to meet underwater acoustic channel capacity.

A b initio calculations have been performed to study the complexes of XeOF 2 and a series of π systems including ethyne, ethene, benzene, pyrrole, furan, and thiophene. More than two structures were obtained for each complex with an aerogen–π bond. The configuration of complex has a significant effect on its stability. The strength of aerogen–π interaction is comparable with that of lone pair–aerogen interaction and conventional hydrogen bonds. A breakdown of the aerogen–π interaction attributes its stability to approximately equal parts electrostatic and polarization energies, with a relatively smaller contribution from dispersion energy.

Ab initio calculations have been performed to study the influence of hybridization, substitution, and cooperativity on the tetrel bond in the complexes of PySiX3 (Py=pyridine and X=halogen). The tetrel bond becomes stronger in the order of p-PySiF3⋯NCH(sp)

Hearing loss (HL) is one of the most common human defects which affects millions of people globally. The identification of deafness-related genes or loci may facilitate basic and clinical translational research on this disorder. Here, we investigated a Chinese family with autosomal recessive non-syndromic hearing impairment. Using targeted massively parallel sequencing, we identified a novel homozygous mutation, c.3525_3526insA and p.Q1175fsX1188 (NM_016239), in exon 2 of MYO15A. Sanger sequencing confirmed that affected siblings were homozygous for the mutation, whereas both normal hearing parents were heterozygous. The mutation was absent in 96 healthy controls and public databases. The insertion leads to a frameshift and a truncated form of the protein, resulting in the pathogenic effect of hearing loss for the patients. Mutations in exon 2 of MYO15A may cause a less severe phenotype, facilitating the rapid identification of mutations in exon 2 among the 66 exons when linkage of less severe hearing loss to Deafness, Autosomal Recessive 3 (DFNB3) is detected. Our data provide additional molecular information for establishing a better genotype-phenotype understanding of DFNB3.

A new acylhydrazine-derived Schiff base fluorescence probe DMI based on “ON-OFF-ON” fluorescence strategy was presented in this paper. Probe DMI could detect Cu2+ selectively and sensitively with dramatic fluorescence quenching in CH3OH-PBS (v/v = 3:7) mixed solution. Once the complex DMI-Cu2+ interacted with S2−, 10.67-folds fluorescence increase was induced via a displacement mechanism under the same experimental conditions. The corresponding detection limits for Cu2+ and S2− were calculated to be 1.52 × 10−8 M and 1.79 × 10−8 M, respectively. The structures of DMI and DMI-Cu2+ were systematically characterized by Job's plot analysis, ESI-MS, IR, X-ray diffraction and density functional theory calculations. Furthermore, fluorescence imaging in MCF-7 cells and zebrafish demonstrated the probe DMI could act as a useful tool to monitor and track intracellular Cu2+ and S2−, which was encouraged by remarkable fluorescence performance and low cytotoxicity. Importantly, the complex DMI-Cu2+ could be applied to detect corrupt blood samples, which could estimate the time of death.

After two hundred years development, surface and interface science becomes an active discipline with flourishing development tendency. As one of the most important phenomenon of surface science, superlyophobic/superlyophilic has attracted widespread attentions of scientists and engineers. Inspired by the natural organism, scientists have designed various biomimetic materials with special wettability, such as asymmetric spider silk surface with dynamic wetting behavior, continuous directional water transport Nepenthes alata surface et al. These superlyophobic/superlyophilic materials are widely used in self-cleaning, water collection, liquid transportation and separation and many engineering domains. Among them, the liquid transportation and separation, including separation of oil-water mixture, immiscible organic liquids mixture and oil-water emulsion, are lucubrated by more and more scientists. Many one-dimensional and two-dimensional liquid transportation and separation materials with superlyophobicity/superlyophilicity have been successfully designed and used in scientific researches and technology applications. With the principle of sustainable development, we expect that these bioinspired liquid transportation and separation materials can be applied into the actual production and living in the near future.

Recently, C3B monolayer has attracted much attention due to its potential applications in many fields. In this work, we have further explored its application as gas sensor. Since the experimentally synthesized C3B is usually C excess, we have theoretically studied the adsorption behaviors of N2, O2, CO2, H2O, CH4, NO, NO2, CO and NH3 on C-excess C3B (C3+xB, x = 0.1, 0.2, 0.3, 0.4 and 0.6), the cases on pure C3B are also calculated for the comparison. Our results reveal that C3+xB undergoes the changes from metal to semiconductor after the adsorption of NO2 and NO, which implies its high sensitivity towards these two molecules. Among all the gases, only NO, NO2, CO and NH3 could adsorb on the C3+xB, and CO/NH3 and NO/NO2 prefer to adsorb on the B-site and doped C-site in C3+xB, respectively. In this regard, C3+xB exhibits the high selectivity towards NO and NO2 irrespective of the existence CO, NH3 and other gases. Also, the adsorbed gases on C3+xB could be easily removed by injecting electrons into the system. Based on these results, we proposed that the C-excess C3+xB is a promising reusable material as NO2 and NO sensor with high sensitivity and selectivity.

Overexpression of tumor biomarker glutathione (GSH) has been documented in numerous types of cancers, therefor GSH-activated light-up chemosensors for tumor identification require great attention. A new colorimetric/fluorescent probe (7-(diethylamino)-2-oxo-2H-chromen-3-yl)methylene)-4-(dimethylamino) benzohydrazide (HL) was prepared, which could be applied in discriminating Cu2+ and further recognizing GSH based on its Cu complex. Firstly, the probe HL toward Cu2+ exhibited selective fluorescence quenching and obvious color change from yellow to orange-red under visible light. Further, when GSH was introduced to the Cu2+-2HL system, the fluorescence recovered rapidly due to the high affinity of GSH to Cu2+, meanwhile the color reverted back to former yellow. Based on fluorescence titration, the detection limits were calculated as 2.40 × 10−8 M and 1.29 × 10−7 M for Cu2+ and GSH, respectively. The combination mode of HL with Cu2+ was investigated in detail by Job plots, ESI-MS, FT-IR, and DFT studies. Probes HL and Cu2+-2HL showed relatively less toxicity and were employed for biological imaging in cells and zebrafish. Remarkably, the detection for endogenous GSH by this developed sensor platform implied great potential application prospect in cancer diagnosis.

Identifying and detecting similar target cations through combining “turn on” and “turn off” fluorescence mechanism is effective and challenging. Now a new colorimetric and ON-OFF-ON fluorescent probe N′-((7-(diethylamino)-2-oxo-2H-chromen-3-yl)methylene)-3-hydroxy-2-naphthohydrazide (L) was reported, which could detect Cu2+ and Co2+ in phosphate buffered CH3CH2OH-H2O solvent system. With the assistance of glutathione and pH adjustment, a unique ON-OFF-ON fluorescence detection strategy could be achieved for distinguishing Cu2+ and Co2+. The emission of probe could recover from the L-Cu2+ and L-Co2+ system by addition of GSH or adjusting pH value to 4, respectively, which is due to the abolishment of paramagnetic Cu2+/Co2+. Based on fluorescence titration experiments, the limit of detection was determined as 3.84 × 10−9 M and 4.55 × 10−9 M for Cu2+ and Co2+, respectively. Meanwhile, the detection limit reached 6.21 × 10−8 M for Cu2+ and 6.96 × 10−8 M for Co2+ according to absorbance signal output. Fast recognition of Cu2+/Co2+ can be achieved by obvious color changes from green to colorless under UV light, as well as from yellow to orange-red in room light. The binding mode of L toward Cu2+ and Co2+ have been systematically studied by Job's plot analysis, ESI-MS, IR and density functional theory calculations. Most strikingly, further practical applications of the probe L in fluorescence imaging were investigated in MCF-7 cells and zebrafish due to its low cytotoxicity and good optical properties, suggesting that L could serve as a fluorescent sensor for tracking Cu2+ and Co2+ in vivo.

Colloidal silica and ceria based slurries, both using KMnO4 as an oxidizer, for chemical mechanical polishing (CMP) of Si-face (0 0 0 1) 6H-SiC substrate, were investigated to obtain higher material removal rate (MRR) and ultra-smooth surface. The results indicate that there was a significant difference in the CMP performance of 6H-SiC between silica and ceria based slurries. For the ceria based slurries, a higher MRR was obtained, especially in strong acid KMnO4 environment, and the maximum MRR (1089 nm/h) and a smoother surface with an average roughness Ra of 0.11 nm was achieved using slurries containing 2 wt% colloidal ceria, 0.05 M KMnO4 at pH 2. In contrast, due to the attraction between negative charged silica particles and positive charged SiC surface below pH 5, the maximum MRR of silica based slurry was only 185 nm/h with surface roughness Ra of 0.254 nm using slurries containing 6 wt% colloidal silica, 0.05 M KMnO4 at pH 6. The polishing mechanism was discussed based on the zeta potential measurements of the abrasives and the X-ray photoelectron spectroscopy (XPS) analysis of the polished SiC surfaces.

The halogen-bonded complexes of iodobenzene and its derivatives with HCN have been used to study the non-additivity of F substituent using quantum chemical calculations in views of interaction energy and binding distance. The F substitution in iodobenzene strengthens the halogen bond, depending on the substitution number and position of F atom in the aromatic ring. The enhancement of F substituent has been analyzed by means of molecular electrostatic potential, electron density, charge transfer, and orbital interaction. The good linear relationship between the interaction energy and these terms has been found. There is non-additivity for the F substituent in strengthening the halogen bond. Energy decomposition indicates that the electrostatic interaction plays a dominant role in enhancing the halogen bond.

Generally, intercalation occurs when foreign atoms intercalate into multi-layer structures, while adsorption occurs when foreign atoms interact with monolayer structures or surfaces. We performed an investigation on the Mg intercalation into Ti2C building block (MXene) from first-principles simulation. We found that Mg can favorably intercalate into MXene, forming the stable compound Ti2MgC, which corresponds to the stage I in the Li intercalation into graphite. Based on the evaluation of the average cell potential and the energy barrier of Mg diffusion for the most energetically stable structure, our results suggest that Ti2MgC is a potential anode for Mg ion batteries.

F2CX (X = Se and Te) have two Lewis acid sites of σ-hole and π-hole located respectively in the vicinity of X and C ends, participating in the chalcogen and tetrel bonds with HCN and NH3, respectively. F2CSe forms a stronger tetrel bond, while F2CTe forms a stronger chalcogen bond. F2CX shows weaker tetrel and chalcogen bonds in the ternary system, exhibiting anticooperativity with some different features from positive one. The nature of two interactions and the origin of anticooperativity have been analyzed by means of energy decomposition, molecular electrostatic potential, and orbital interaction.

The complexes F2XO⋯NCH⋯NCH and F2XO⋯HCN⋯HCN (X = C and Si) have been studied by quantum chemical calculations at the MP2/aug-cc-pVTZ level. These four trimers show similar stability except F2SiO⋯HCN⋯HCN. The C–H⋯N hydrogen bond is enhanced by the presence of tetrel bond in F2XO⋯NCH⋯NCH. Interestingly, the stronger tetrel bond in F2SiO⋯NCH⋯NCH exhibits a greater enhancement than the weaker one in F2CO⋯NCH⋯NCH. The positive cooperativity is mainly attributed to the polarization and dispersion energies in the former but to the polarization energy in the latter. The tetrel bond and C H⋯O hydrogen bond are also strengthened each other in HCN⋯F2XO⋯HCN. The tetrel bonds are weakened in HCN⋯F2XO⋯NCH, where the weakening is caused mainly by electrostatic energy for HCN⋯F2CO⋯NCH and by electrostatic and polarization energies for HCN⋯F2SiO⋯NCH. The C H⋯N and C H⋯O hydrogen bonds show a positive cooperative effect in F2XO⋯HCN⋯HCN due to the polarization interaction.

A weak interaction was found between the two methyl groups in the complexes of XCH3–CH3BH2 (X = F, CN, NO2, HCO, and SOCH3), where the former methyl group acts as a Lewis acid and the latter one as a Lewis base. This directional interaction has small interaction energy, accompanied with some small changes in geometry and spectroscopy. Stronger Lewis acids FYH3 (Y = Si, Ge, and Sn) as well as Lewis bases CH3BeH and CH3MgH were compared. Dispersion energy is the major source of attraction and electrostatic contribution grows up to exceed dispersion energy for stronger interactions.

Ab initio calculations have been performed for the complexes of pyridine with 1,2-dihydro-1,2-azaborine (1), 1,3-dihydro-1,3-azaborine (2), 1,4-dihydro-1,4-azaborine (3), and their F and methyl derivatives to compare the influence of both substituents adjoined to the C and B atoms on the strength of hydrogen bonding. The NH⋯N hydrogen bond is enhanced by the substituent F whether it is connected to C or B atom, and the enhancing effect is bigger for one bonded to the C atom. The role of methyl group depends on the position of the substitution. NBO analyses showed that H, F, and methyl substituents are electron-withdrawing in the formation of complexes, but the electron-withdrawing ability of the methyl group bonded to the B atom is smaller than that of the corresponding H atom. The cooperativity between different types of interactions in 1 and its derivatives has also been discussed in the change of interaction energy and binding distance.

Excited state proton transfer process (ESPT) has potential applications in fluorescent probes due to the large Stokes shift. In this work, we properly designed a series of F anion NIR fluorescent sensors with 10-hydroxybenzo[h]quinoline (HBQ) backbone which exhibits fast intramolecular ESPT. By systematically investigating the substituent effects of a series of electron donor groups and electron acceptor groups at the pyridine site, we could not only modulate the dynamics of the proton transfer process but also the photophysical properties. It is revealed that ESPT occurs very fast in the derivatives, and the emission spectra can be expanded from 529 to 754 nm. Further, we investigated the sensitivity of all the derivatives towards F anion by studying the structural and (absorption and emission) spectral changes in the anion complex and the bare sensor without including F anion. The result shows that 4CN-HBQ and 4CF3-HBQ are very sensitive towards F anion among all the HBQ derivatives. Besides, we investigated the selectivity towards F anion among anions (F−, Cl−, and Br−) structurally and spectrally. The calculated result shows that 4CN-HBQ and 4CF3-HBQ are selective to F anion by forming inter molecular hydrogen bond H-F… O with F−, while Cl− and Br− cannot form, which induces large variances in absorption spectra between the anion complexes. All these results demonstrate that 4CN-HBQ and 4CF3-HBQ are the best candidates as NIR fluorescent sensors for F anion detection among HBQ derivatives. This article not only gives a comprehensive understanding of the substitution effect on the HBQ backbone but also provides an insight into the potential use of HBQ based chromophore.

The interaction between glycine and F2CO/F2SiO occurs through the formation of a π-tetrel bond between the C/Si atom and a carboxyl O atom. The interaction energy is some 20 kJ/mol for the C⋯O tetrel bond, but exceeds 300 kJ/mol for Si⋯O. As part of the latter complexation process, the proton engaged in the intramolecular OH··N H-bond is transferred across to the N, forming a zwitterion. This Si⋯O tetrel bond is more effective in inducing this proton transfer than is placement of the glycine in an aqueous medium, complexation with an anionic BH4−, or adding an electron to the glycine.

Collaborative recommendation (CR) is a popular method of filtering items that may interest social users by referring to the opinions of friends and acquaintances in the network and computer applications. However, CR involves a cold-start problem, in which a newly established recommender system usually exhibits low recommending accuracy because of insufficient data, such as lack of ratings from users. In this study, we rigorously identify active users in social networks, who are likely to share and accept a recommendation in each data cluster to enhance the performance of the recommendation system and solve the cold-start problem. This novel modified CR method called div-clustering is presented to cluster Web entities in which the properties are specified formally in a recommendation framework, with the reusability of the user modeling component considered. We improve the traditional k-means clustering algorithm by applying supplementary works such as compensating for nominal values supported by the knowledge base, as well as computing and updating the k value. We use the data from two different cases to test for accuracy and demonstrate high quality in div-clustering against a baseline CR algorithm. The experimental results of both offline and online evaluations, which also consider in detail the volunteer profiles, indicate that the CR system with div-clustering obtains more accurate results than does the baseline system.

The complexes MX 3 MCN-YF and MX 3 MCCY-NH 3 (M = Be, Mg, Ca; X = F, Cl, Br; Y = H, Cl, Li) have been studied at the MP2(FC)/6-311++G(2d,2p) level. For comparison, XMCN-YF and XMCCY-NH 3 complexes were also investigated. The superhalogen MX 3 is favorable for the formation of complexes when it exists in the electron donor but unfavorable in the electron acceptor. The interaction strength is related with the nature of M and X atoms. With the increase of M atomic mass, the interaction strength becomes larger for MX 3 MCN-YF but smaller for MX 3 MCCY-NH 3 . The effect of X on the interaction strength is smaller than that of M. The electrostatic potential analyses show that the electron-withdrawing ability of the superhalogen weakens in the electron donor and acceptor with respect to the halogen atom.

The Li3M–XY (M = Cl, Br, and I; XY = ClCl, BrBr, ClF, BrCl, and BrF) complexes have been studied with theoretical calculations at the MP2/aug-cc-pVTZ level. The results showed that the Br atom in Li3Br is a stronger halogen acceptor than the Cl atom in Li3Cl when it interacts with dihalogen molecules although their strength difference is small and the Li3I is the strongest Lewis base. To the best of our knowledge, this is the first report on halogen bonds involved with superatoms. The formation of halogen bonding has been analyzed with natural bond orbital (NBO), atoms in molecules (AIM), and energy decomposition. The results showed that the orbital interaction plays an important role for the stabilization of the complexes, which is different from conventional halogen bonds.

The HAlP and HPAl radicals have been studied using CASSCF, CASPT2, and CCSD(T) methods. The geometries of the stationary points were optimized at the CASPT2/ANO and CCSD(T)/aug-cc-pVTZ levels. For the double states, the potential energy curves of isomerization reactions between HAlP and HPAl were calculated as functions of HAlP bond angle. The calculated results showed that the ground-state HAlP is linear, while the ground-state HPAl is bent, which is in contradiction to Walsh’s rules predicting linear structures for the HXY systems containing 10 or less valence electrons. Some quartet states of HAlP and HPAl were also calculated.

The insertion reactions of the germylenoid H 2 GeLiF with CH 3 X (X = F, Cl, Br) were studied for the first time by using the DFT B3LYP and QCISD methods. The theoretical calculations predicted that along the potential energy surface, there are one precursor complex, one transition state, and one intermediate which connect the reactants and the products. The elucidations of the mechanism of these insertion reactions provide a new reaction mode of germanium–carbon bond formation.

A theoretical study of the complexes formed between HArF and XH 2 P (X = F, Cl, and Br) has been carried out using ab initio methods (MP2/aug-cc-pVDZ, MP2/aug-cc-pVTZ, and CCSD(T)/aug-cc-pVTZ). Three minima were found, which correspond to a hydrogen-bonded complex (I), a pnicogen-bonded complex (II), and a halogen-bonded complex (III). The pnicogen-bonded complex is the most stable, followed by the hydrogen-bonded complex, and the halogen-bonded complex is the least stable. The Ar–H bond is enhanced in FH 2 P–HArF–I complex and exhibits a blue shift, while it is weakened in ClH 2 P–HArF–I and BrH 2 P–HArF–I complexes and shows a red shift. A blue shift is also found for the distant Ar–H bond in the halogen-bonded and pnicogen-bonded complexes. These complexes have been understood with the electrostatic potentials and symmetry adapted perturbation theory (SAPT) method.

In this paper, three complexes of HArF and acetylene have been observed and they are combined through Ar H⋯π and C H⋯F H-bonds, respectively. The former H-bond is weaker than the latter one. The F substituent in acetylene expands their strength difference, the Cl and Br substitutents attenuate their strength difference, but the I and At substituents make the former H-bond stronger than the latter one. The methyl group in propyne brings out a similar effect with the I and At substitutents but the effect is more prominent. The C H⋯F H-bond has an unmonotonic dependence on the noble atomic number and HArF forms the strongest C H⋯F H-bond. Both types of H-bonds have been analyzed with the natural bond orbital (NBO) and symmetry adapted perturbation theory (SAPT) methods.