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[Display omitted] • A novel symmetrically double-armed salamo type fluorescent sensor BMS was synthesized. • The high sensitivity and selectivity of BMS in the recognition of MnO 4 - were investigated. • The limit of detection (LOD), limit of quantification (LOQ), and the binding constant (K a) were calculated. • The recognition mechanism of MnO 4 - by BMS has been postulated. • The energy gaps before and after recognition were analyzed by DFT calculation. The symmetrically double-armed salamo type fluorescent sensor BMS , incorporating benzimidazole units, was designed and synthesized. Showcasing remarkable specificity and responsiveness to MnO 4 - within a DMSO:H 2 O (V/V = 9:1, pH = 7.2) Tris-HCl buffer medium, it enabled dual-channel detection of MnO 4 - through fluorescent and colorimetric changes. Critical experimental parameters, including detection and quantification thresholds (LOD and LOQ) along with binding affinity constants (K a), were calculated using the Origin software. A rational interaction mechanism between BMS and MnO 4 - was deduced, based on fluorescence titration, Electrospray Ionization Mass Spectrometry (ESI-MS), Ultraviolet–Visible Spectroscopy (UV–Vis), Infrared Spectroscopy (IR), Stern-Volmer plots, and Density Functional Theory (DFT) computations. Additionally, the sensor BMS was applied to monitor MnO 4 - in real water samples. Advancing its practical utility, BMS was fabricated into test strips for the selective detecting of MnO 4 -. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) analysis has attracted accumulated attention on diagnosis of diseases and high-efficiency photosensitizers are urgently needed. In this work, N-doped sheet-like porous carbon (N-PC) was prepared by thermal stripping of Zn2+ from zeolitic imidazole framework-8 (ZIF-8), followed by in situ formation of gold nanoparticles (Au NPs) embedded in the N-PC (termed Au NPs@N-PC). Also, the zinc meso-tetra (4-carboxyphenyl) porphine (ZnP) behaved as photosensitizer, which was covalently linked with Au NPs@N-PC (ZnP-Au NPs@N-PC), achieving the 9.2-fold enhancement in the photocurrents by using dopamine (DA) as donor. Next, the PEC mechanism was strictly discussed by UV–vis diffuse reflectance (DLS) spectroscopy, fluorescence (FL) and density functional theory (DFT) calculations. By virtue of the excellent PEC property, a label-free "signal off" PEC aptasensor was constructed based on the ZnP-Au NPs@N-PC for ultrasensitive detection of protein tyrosine kinase (PTK-7). The established biosensor showed a wider linear range of 10.00 pg mL−1 to 1.00 μg mL−1 (R 2 = 0.99) and a lower limit of detection (LOD, 1.42 pg mL−1), coupled by showing acceptable results for diagnosis of gliomas. Hence, this research opens a valuable avenue for synthesis of advanced photosensitizer and holds huge potential in biomedical field. • The Au NPs were in situ embedded on the pores of the N-PC. • The Au NPs@N-PC promoted photoelectron transfer of ZnP for signal enhancement. • The PEC biosensor was built for the detection of PTK-7 in glioma samples. [ABSTRACT FROM AUTHOR]

The WS 2 /WSSe and WSSe/WS 2 bilayers are constructed using single-layer WS 2 and WSSe with a lattice mismatch rate of only 1.85 %, and their structural properties, carrier mobility, electrical properties, and photocatalytic performance are performed using density functional theory. The carrier mobility of WS 2 /WSSe and WSSe/WS 2 bilayers is better than that of single-layer WS 2. And the conductivity of the WSSe/WS 2 bilayer in the Zigzag direction is superior to that in the Armchair direction. The results of band structure using the HSE06 method demonstrate that the most stable WS 2 /WSSe and WSSe/WS 2 bilayers are type-II band alignment. WS 2 /WSSe and WSSe/WS 2 bilayers can undergo redox reactions at pH = 0 and pH = 7 respectively. And they all emerge a built-in electric field to cause photo-generated carriers to recombine between the layers to upgrade the photocatalytic performance of the bilayer, which is a typical S-scheme heterojunction. And the power conversion efficiency (PCE) of the WS 2 /WSSe and WSSe/WS 2 bilayers are 15.5 % and 15.7 % respectively, so the utilization rate of sunlight is relatively high. In general, WS 2 /WSSe and WSSe/WS 2 bilayers are ideal materials in the field of photocatalytic water splitting. [Display omitted] • The hole mobility in the zigzag direction of the WS 2 /WSSe can reach 2278 cm2/Vs. • The WS 2 /WSSe and WSSe/WS 2 bilayers are S-scheme heterojunction. • The PCE of WS 2 /WSSe and WSSe/WS 2 bilayers can reach 15.5% and 15.7%. [ABSTRACT FROM AUTHOR]

The effect of the timing of adding 1 wt% decalin as a hydrogen donor on heavy oil visbreaking was studied. Experiments show that either premixing decalin with heavy oil or adding decalin during the reaction accelerates the formation of light distillates and improves the efficiency of viscosity reduction. Premixing with heavy oil is an appropriate way to add decalin. After 10 min of reaction at 400 ℃, the viscosity reduction rate of the product reaches 90% and the asphaltene content of the product is 1.8 wt% lower than that of the raw heavy oil. According to theoretical calculations, the active hydrogens of decalin preferentially saturate the aromatic C radicals that are critical for condensation. The equilibrium constant of the H-donation reaches the order of 105, while the activation energy of the reaction is only about 26 kJ/mol. The thermal cracking of decalin itself releases active and small-sized radicals, which accelerate visbreaking by participating in the dealkylation network of heavy oil molecules. • Decalin cracking releases radicals with high activity and diffusivity. • Addition of decalin in visbreaking greatly accelerates viscosity reduction. • Decalin selectively saturates aromatic C radicals vital for condensation. • Premixing decalin with heavy oil inhibits condensation in early reaction stage. • Premixing decalin as a hydrogen donor with heavy oil in visbreaking is recommended. [ABSTRACT FROM AUTHOR]

[Display omitted] • WS 2 with W defect can be used to capture NO and as the NO 2 sensor. • Adsorption of NO 2 can alter the band gap type of WS 2 for intrinsic and S defect. • WS 2 with W defect makes an ideal reversible sensor for detecting CO and NH 3. The magnetic and electronic behaviors of four toxic gas molecules (CO, NH 3 , NO, and NO 2) adsorbed on intrinsic and defective (V W /WS 2 or V S /WS 2) WS 2 are systematically discussed using density functional theory. The adsorption energy of NO-V W /WS 2 is reduced more compared to that of NO adsorbed on intrinsic WS 2 , indicating that V W /WS 2 can be used to capture NO. The adsorption of the four toxic gas molecules shortens the band gap of the defective WS 2. The introduction of the S defect changes the type of band gap of the system. More interestingly, the adsorption of NO 2 (NO) changes the system from a direct bandgap for intrinsic WS 2 (V W /WS 2) to an indirect bandgap, while the introduction of NO 2 changes the system from an indirect bandgap for V S /WS 2 to a direct bandgap. Finally, the shorter recovery times for CO and NH 3 -V W /WS 2 compared to CO and NH 3 adsorbed on intrinsic WS 2 suggest that V W /WS 2 makes an ideal reversible sensor for detecting CO and NH 3. In conclusion, the adsorption of gas molecules and the defect can modulate the magnetic and electronic properties of WS 2. Importantly, intrinsic and defective WS 2 will facilitate gas sensing and detection of toxic gases. [ABSTRACT FROM AUTHOR]

The strategy of adding tetralin as a H-donor in the thermal processing of heavy oil was investigated by experimental characterization and theoretical calculations. According to the experiments, the timing of adding 1 wt% of tetralin has a great influence on the visbreaking performance of heavy oil. Calculations based on density functional theory showed that benzyl radicals released from the thermal cracking of tetralin accelerate the dealkylation that determines the heavy oil upgrading. Meanwhile, H α provided by tetralin is able to selectively saturate aromatic C radicals which are essential for condensation. Compared with the conventional H-donor addition, i.e., pre-mixing of tetralin with heavy oil, a similar viscosity reduction rate of about 98% can be obtained during the visbreaking with delayed tetralin addition. Furthermore, the addition of tetralin before the significant occurrence of condensation further increases the conversion of vacuum residue fraction by 3.4% and reduces the asphaltene content of the product by 2.6 wt%. [Display omitted] • Tetralin cracking releases benzyl radicals which accelerate heavy oil upgrading. • H α provided by tetralin selectively saturates aromatic C radicals. • Pre-mixing of tetralin with heavy oil affects sufficient condensation inhibition. • In visbreaking tetralin should be added before apparent occurrence of condensation. • In delayed coking the addition of tetralin is not recommended. [ABSTRACT FROM AUTHOR]

The performance of introducing a free radical initiator into dealkylation-based visbreaking of heavy oil in the N 2 or supercritical benzene (SC benzene) medium was investigated. Calculations based on density functional theory show that the introduction of di-tert-butyl peroxide (DTBP) into heavy oil visbreaking results in the formation of alkyl C radicals similar to those naturally formed in high temperature initiation. The visbreaking in SC benzene environment is sensitive to the introduction of DTBP, which is different from the visbreaking in N 2 environment. According to reaction kinetics analysis, the presence of SC benzene solvent and the introduction of DTBP greatly accelerate the dealkylation related lumped reactions. Benefiting from improved diffusion environment, the superimposed radicals resulting from DTBP introduction effectively participate in visbreaking and selectively accelerate dealkylation. After only 10–20 min of reaction at 380 °C, visbreaking products with satisfactory viscosity reduction, reduced asphaltene content and improved light component yield can be obtained. • Initiator-introduced heavy oil visbreaking in supercritical benzene was examined. • DTBP introduction results in rapid superposition of alkyl C radicals. • The presence of supercritical benzene accelerates visbreaking. • Superimposed radicals effectively participate in visbreaking in SC benzene. • Best upgrading is obtained in DTBP-introduced visbreaking in SC benzene. [ABSTRACT FROM AUTHOR]

The difficulty of the H-abstraction of alkyl radicals from PAHs or hetero-PAHs follows the order: S-containing heterocycles > PAHs > N-containing heterocycles. • H-abstraction of CH 3 or C 2 H 5 from PAHs or hetero-PAHs was investigated. • CH 3 instead of C 2 H 5 is responsible for aromatic C radical formation on PAHs. • Activation entropy determines the difference in k T S T of H-abstraction on PAHs. • H-abstraction difficulty: S-containing heterocycles > PAHs > N-containing heterocycles. To understand the condensation during heavy oil thermal processing, the formation of aromatic carbon radicals by H-abstraction of methyl radicals (CH 3) or ethyl radicals (C 2 H 5) from polycyclic aromatic hydrocarbons (PAHs) or heterocyclic aromatic hydrocarbons (hetero-PAHs) was studied by density functional calculation. The H-abstraction from different PAHs all has a positive standard state Gibbs free energy change, while increasing reaction temperature or radical concentration promotes the reaction to proceed spontaneously. CH 3 mainly contributes to the formation of aromatic carbon radicals on PAHs, and the activation entropy of H-abstraction determines the difference in reaction rate constants. The particularity of H-abstraction from hetero-PAHs is reflected at the α-site of heterocycles. The H-abstraction from N-containing hetero-PAHs occurs preferentially at the α-site of heterocycles, and both CH 3 and C 2 H 5 could participate in abstracting the α-H. The H-abstraction from S-containing hetero-PAHs occurs preferentially on coupled aromatic rings, showing reaction behavior similar to the H-abstraction on PAHs. [ABSTRACT FROM AUTHOR]