Nonequilibrium Adsorption and Reorientation Dynamics of Molecules at Electrode/Electrolyte Interfaces Probed via Real-Time Second Harmonic Generation

Nonequilibrium adsorption and subsequent reorientation of organic molecules at electrode/electrolyte interfaces are important steps in electrochemical reactions and other interfacial processes, yet real-time quantitative characterization and monitoring of these processes, particularly for the reorientation step, are still challenging experimentally. Herein, we investigated the nonequilibrium adsorption process of 4-(4-(diethylamino)­styryl)-<i>N</i>-methyl-pyridinium iodide (D289) molecules from acetonitrile solution onto a polycrystalline platinum electrode surface using real-time second harmonic generation (SHG) in combination with the potential step method. The time-dependent SHG curves exhibit two distinct regimes, which were interpreted with a two-step adsorption model consisting of a fast adsorption and a slow reorientation step for D289 on the surface. D289 was assumed to initially adsorb in an orientation perpendicular to the surface and then reorient to a parallel orientation. We derived a quantitative mathematical expression containing a biexponential function to fit the temporal SHG curves and obtain the rate constants for the two steps. The rate constants for fast adsorption and the slower reorientation processes show similar potential-dependent behavior: the rate decreases with an increase in the negative potential. We further proposed a molecular mechanism involving the displacement of D289 and CH₃CN molecules adsorbed on the electrode interface to explain this potential-dependent behavior. On the basis of such analysis, we obtained a detailed picture of the adsorption of D289 molecules on the Pt electrode/CH₃CN electrolyte, which consists of three consecutive steps: diffusion, adsorption, and reorientation. The results of this study may shed light on adsorption mechanisms at the electrode/electrolyte interface as well as at biological and other functional material interfaces

In Situ Heterodyne-Detected Second-Harmonic Generation Study of the Influence of Cholesterol on Dye Molecule Adsorption on Lipid Membrane

Cholesterol plays an essential role in regulating the functionality of biomembranes. This study employed in situ second-harmonic generation (SHG) to investigate the adsorption behavior of the dye molecule 4-(4-(diethylamino)styryl)-N-methyl-pyridinium iodide (D289) on a biomimic membrane composed of 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (sodium salt) (DPPG) and cholesterol. The time-dependent polarization SHG intensity exhibited an initial rapid increase, followed by a subsequent decline. The initial increased SHG intensity is responsible for the electrostatic interaction-driven adsorption of D289 onto the membrane, while the decrease in the SHG signal results from the broadening of the orientation distribution within the membrane. Heterodyne-detected SHG (HD-SHG) measurements demonstrated that the adsorption of dye molecules influenced the phase of the induced electric field. The interfacial potential Φ(0) as a function of time was measured, and we found that even after reaching a stable Stern layer state, the diffusion layer continued to exhibit a dynamic change. This study offers a comprehensive understanding of the influence of cholesterol on adsorption, reorientation dynamics, and dynamic changes in the reorientation of water in the diffusion layer

An approach to developing customized total knee replacement implants

Total knee replacement (TKR) has been performed for patients with end-stage knee joint arthritis to relieve pain and gain functions. Most knee replacement patients can gain satisfactory knee functions; however, the range of motion of the implanted knee is variable. There are many designs of TKR implants; it has been suggested by some researchers that customized implants could offer a better option for patients. Currently, the 3-dimensional knee model of a patient can be created from magnetic resonance imaging (MRI) or computed tomography (CT) data using image processing techniques. The knee models can be used for patient-specific implant design, biomechanical analysis, and creating bone cutting guide blocks. Researchers have developed patient-specific musculoskeletal lower limb model with total knee replacement, and the models can be used to predict muscle forces, joint forces on knee condyles, and wear of tibial polyethylene insert. These available techniques make it feasible to create customized implants for individual patients. Methods and a workflow of creating a customized total knee replacement implant for improving TKR kinematics and functions are discussed and presented in this paper

Fabrication of Supramolecular Chirality from Achiral Molecules at the Liquid/Liquid Interface Studied by Second Harmonic Generation

We present the investigation into the supramolecular chirality of 5-octadecyloxy-2-(2-pyridylazo)­phenol (PARC18) at water/1,2-dichloroethane interface by second harmonic generation (SHG). We observe that PARC18 molecules form supramolecular chirality through self-assembly at the liquid/liquid interface although they are achiral molecules. The bulk concentration of PARC18 in the organic phase has profound effects on the supramolecular chirality. By increasing bulk concentration, the enantiomeric excess at the interface first grows and then decreases until it eventually vanishes. Further analysis reveals that the enantiomeric excess is determined by the twist angle of PARC18 molecules at the interface rather than their orientational angle. At lower and higher bulk concentrations, the average twist angle of PARC18 molecules approaches zero, and the assemblies are achiral; whereas at medium bulk concentrations, the average twist angle is nonzero, so that the assemblies show supramolecular chirality. We also estimate the coverage of PARC18 molecules at the interface versus the bulk concentration and fit it to Langmuir adsorption model. The result indicates that PARC18 assemblies show strongest supramolecular chirality in a half-full monolayer. These findings highlight the opportunities for precise control of supramolecular chirality at liquid/liquid interfaces by manipulating the bulk concentration

Table_2_Integrated transcriptome and metabolome profiling reveals mechanisms underlying the infection of Cytospora mali in “Jin Hong” branches.XLSX

IntroductionValsa canker, caused by Cytospora mali, is a destructive disease in apple production. However, the mechanism by which apple defend against C. mali infection remains unclear.MethodsIn this study, the integrative transcriptional and metabolic analysis were used to investigate the responses of the ‘Jin Hong’ apple branches to the invasion of C. mali.Results and DiscussionResults showed that the differentially expressed genes were mainly enriched in the pathways of carbon metabolism, photosynthesis-antenna proteins, and biosynthesis of amino acids pathways. Additionally, the differentially accumulated metabolites were significantly enriched in aminoacyl-tRNA biosynthesis, fructose and mannose metabolism, and alanine, aspartate, and glutamate metabolism pathways. Conjoint analysis revealed that C. mali infection significantly altered 5 metabolic pathways, 8 highly relevant metabolites and 15 genes of apples. Among which the transcription factors WRKY and basic domain leucine zipper transcription family were induced, the α-linolenic acid and betaine were significantly accumulated in C. mali infected apple stems. This work presents an overview of the changes in gene expression and metabolic profiles in apple under the inoculation of C. mali, which may help to further screen out the mechanism of plant-pathogen interaction at the molecular level.</p

Table_5_Integrated transcriptome and metabolome profiling reveals mechanisms underlying the infection of Cytospora mali in “Jin Hong” branches.XLSX

IntroductionValsa canker, caused by Cytospora mali, is a destructive disease in apple production. However, the mechanism by which apple defend against C. mali infection remains unclear.MethodsIn this study, the integrative transcriptional and metabolic analysis were used to investigate the responses of the ‘Jin Hong’ apple branches to the invasion of C. mali.Results and DiscussionResults showed that the differentially expressed genes were mainly enriched in the pathways of carbon metabolism, photosynthesis-antenna proteins, and biosynthesis of amino acids pathways. Additionally, the differentially accumulated metabolites were significantly enriched in aminoacyl-tRNA biosynthesis, fructose and mannose metabolism, and alanine, aspartate, and glutamate metabolism pathways. Conjoint analysis revealed that C. mali infection significantly altered 5 metabolic pathways, 8 highly relevant metabolites and 15 genes of apples. Among which the transcription factors WRKY and basic domain leucine zipper transcription family were induced, the α-linolenic acid and betaine were significantly accumulated in C. mali infected apple stems. This work presents an overview of the changes in gene expression and metabolic profiles in apple under the inoculation of C. mali, which may help to further screen out the mechanism of plant-pathogen interaction at the molecular level.</p

Table_4_Integrated transcriptome and metabolome profiling reveals mechanisms underlying the infection of Cytospora mali in “Jin Hong” branches.XLSX

IntroductionValsa canker, caused by Cytospora mali, is a destructive disease in apple production. However, the mechanism by which apple defend against C. mali infection remains unclear.MethodsIn this study, the integrative transcriptional and metabolic analysis were used to investigate the responses of the ‘Jin Hong’ apple branches to the invasion of C. mali.Results and DiscussionResults showed that the differentially expressed genes were mainly enriched in the pathways of carbon metabolism, photosynthesis-antenna proteins, and biosynthesis of amino acids pathways. Additionally, the differentially accumulated metabolites were significantly enriched in aminoacyl-tRNA biosynthesis, fructose and mannose metabolism, and alanine, aspartate, and glutamate metabolism pathways. Conjoint analysis revealed that C. mali infection significantly altered 5 metabolic pathways, 8 highly relevant metabolites and 15 genes of apples. Among which the transcription factors WRKY and basic domain leucine zipper transcription family were induced, the α-linolenic acid and betaine were significantly accumulated in C. mali infected apple stems. This work presents an overview of the changes in gene expression and metabolic profiles in apple under the inoculation of C. mali, which may help to further screen out the mechanism of plant-pathogen interaction at the molecular level.</p

Nucleophilic Phosphine-Catalyzed Intramolecular Michael Reactions of <i>N</i>‑Allylic Substituted α‑Amino Nitriles: Construction of Functionalized Pyrrolidine Rings via 5-<i>endo</i>-trig Cyclizations

Pyrrolidine rings are common moieties for pharmaceutical candidates and natural compounds, and the construction of these skeletons has received much attention. α-Amino nitriles are versatile intermediates in synthetic chemistry and have been widely used in the generation of multiple polyfunctional structures. Herein, a novel nucleophilic phosphine-catalyzed intramolecular Michael reaction of <i>N</i>-allylic substituted α-amino nitriles has been developed for the efficient construction of functionalized 2,4-disubstituted pyrrolidines (<i>N</i>-heterocyclic α-amino nitriles) via 5-<i>endo</i>-trig cyclization. Furthermore, the one-pot sequence of the synthesis of pyrrolidine and the subsequent transformations of the functionalized products have also been demonstrated

Table_1_Integrated transcriptome and metabolome profiling reveals mechanisms underlying the infection of Cytospora mali in “Jin Hong” branches.XLSX

IntroductionValsa canker, caused by Cytospora mali, is a destructive disease in apple production. However, the mechanism by which apple defend against C. mali infection remains unclear.MethodsIn this study, the integrative transcriptional and metabolic analysis were used to investigate the responses of the ‘Jin Hong’ apple branches to the invasion of C. mali.Results and DiscussionResults showed that the differentially expressed genes were mainly enriched in the pathways of carbon metabolism, photosynthesis-antenna proteins, and biosynthesis of amino acids pathways. Additionally, the differentially accumulated metabolites were significantly enriched in aminoacyl-tRNA biosynthesis, fructose and mannose metabolism, and alanine, aspartate, and glutamate metabolism pathways. Conjoint analysis revealed that C. mali infection significantly altered 5 metabolic pathways, 8 highly relevant metabolites and 15 genes of apples. Among which the transcription factors WRKY and basic domain leucine zipper transcription family were induced, the α-linolenic acid and betaine were significantly accumulated in C. mali infected apple stems. This work presents an overview of the changes in gene expression and metabolic profiles in apple under the inoculation of C. mali, which may help to further screen out the mechanism of plant-pathogen interaction at the molecular level.</p

Table_3_Integrated transcriptome and metabolome profiling reveals mechanisms underlying the infection of Cytospora mali in “Jin Hong” branches.XLSX

IntroductionValsa canker, caused by Cytospora mali, is a destructive disease in apple production. However, the mechanism by which apple defend against C. mali infection remains unclear.MethodsIn this study, the integrative transcriptional and metabolic analysis were used to investigate the responses of the ‘Jin Hong’ apple branches to the invasion of C. mali.Results and DiscussionResults showed that the differentially expressed genes were mainly enriched in the pathways of carbon metabolism, photosynthesis-antenna proteins, and biosynthesis of amino acids pathways. Additionally, the differentially accumulated metabolites were significantly enriched in aminoacyl-tRNA biosynthesis, fructose and mannose metabolism, and alanine, aspartate, and glutamate metabolism pathways. Conjoint analysis revealed that C. mali infection significantly altered 5 metabolic pathways, 8 highly relevant metabolites and 15 genes of apples. Among which the transcription factors WRKY and basic domain leucine zipper transcription family were induced, the α-linolenic acid and betaine were significantly accumulated in C. mali infected apple stems. This work presents an overview of the changes in gene expression and metabolic profiles in apple under the inoculation of C. mali, which may help to further screen out the mechanism of plant-pathogen interaction at the molecular level.</p