Bell Model Research Articles

ESD Behavior of MWCNT Interconnects—Part II: Unique Current Conduction Mechanism

High-current carrying capacity and superior thermal conductivity have made multiwall carbon nanotubes (MWCNTs) a material for next-generation interconnects. Its distinct electrical and thermal properties result in various physical phenomenon, interaction among which give rise to unique electro-thermal transport. The interaction aggravates in presence of high-electric fields, which generally occur under ESD conditions. In this paper, we present detailed investigation of electro-thermal transport through MWCNTs under ESD conditions. The role of the substrate, MWCNT shells, and sub-bands in ESD current conduction is highlighted, while considering two device architectures—suspended and dielectric-supported MWCNTs. The quantum electron–phonon transport under non-equilibrium (ESD) conditions is explained using CNT band structure and interplay between electrical and thermal transport along the nanotube. The investigation highlights the role of the dielectric substrate in mitigating the detrimental effects of ESD stress. A strong dependence of failure current on metal-MWCNT contact resistance is revealed. The overall breakdown mechanism is found to follow Wunsch–Bell model, indicating a direct scaling between the rate of oxidation of MWCNT shells and injected power.

Molecular dynamics simulations on adhesion of epoxy-silica interface in salt environment

Abstract Epoxy-silica interface exists in various types of newly built as well as aging concrete structures which include flooring and anchoring systems. Sea environment and deicing salt often let the concrete structures be exposed to sodium chloride solution. It is observed from the laboratory evaluation that such exposure often leads to the poor bond durability of epoxy-concrete interface. Yet, there is still a lack of such fundamental understanding as the existing investigations are merely limited to macroscale or mesoscale. Indeed, bond at the interface is governed by the interactions between dissimilar materials lying at the atomistic scale, where atomistic modeling and molecular dynamics simulations can effectively reflect the mechanical behaviors of the bilayer interface. Herein, molecular dynamics simulations together with Bell's model are employed to evaluate the effect of sodium chloride solution on the adhesion at interface between epoxy and silica. It is shown that sodium chloride solution weakens the adhesion significantly. This finding indicates that the bond deterioration at epoxy-concrete interface is critical in the presence of salt solution, which must be considered in the engineering design strategy for offshore and marine structures.

Textual Architecture of a Selected Hard News in English: A Discourse Analysis Approach

This study deals with the analysis of a selected hard news through the adaptation of an eclectic model of analysis by the use of Van Dijk (1988), Bell (1991) and Halliday (1976) models of discourse analysis. Writing news stories is a problematic process because it is not a process of merely putting words together to form a text or report, but it involves the choice of the words and markers that conditioned by the purpose, place, and the readers. The study aims at proposing a theoretical framework for the macro- level analysis of news discourse. It covers the macro level analysis of the chosen hard news. The data of the study is an English news story taken from Washington Times newspaper published on 20th of August 2016. The results of the study display that English hard news stories show certain complexity in their structure. The writer of this hard news story aims at not only conveying information but arising the voice of protest against the government and the court of justice. Such analysis reaches to a conclusion, which emphasizes the idea that the field of discourse can be used for better understanding of the media.

Nanomechanical Phenotypes in Hypertrophic Cardiomyopathy caused by Missense Mutations in Cardiac Myosin-Binding Protein C

We investigate the molecular mechanisms that induce hypertrophic cardiomyopathy (HCM) in the 10-20% of patients who carry missense mutations in MYBPC3, the gene coding for cardiac myosin-binding protein C (cMyBP-C). Our starting point is the striking observation that single-amino-acid changes in this 1274-residue-long structural protein cause HCM in a similar manner to truncations, in which a significant fraction of the protein is missing. We have curated a database of naturally occurring missense variants in MYBPC3 according to their clinical presentation and studied several potential drivers of the disease. Using bioinformatics tools, we found that most pathogenic variants are not predicted to induce gross changes in thermodynamical stability or RNA splicing, two typical properties affected in other monogenic diseases. cMyBP-C slows down muscle contraction by establishing mechanical tethers between myofilaments. Hence, we hypothesized that pathogenic mutations can alter the mechanical properties of cMyBP-C leading to reduced braking ability and hypercontractility, a hallmark of HCM. To test this hypothesis, we have produced several variants of the C3 domain of cMyBP-C, a central domain of the protein without known protein interactors. As expected, most mutants retain close-to-wild-type structure and thermodynamic stability. However, pathogenic mutants show diminished mechanical stability, as determined by single-molecule atomic force microscopy experiments in force-clamp mode. Application of Bell's model to our experimental data show that pathogenic mutants unfold up to 2 times faster than wild-type protein at physiological forces. This mechanical alteration would lead to softer cMyBP-C tethers. Hence, our results support the new idea that nanomechanical phenotypes in cMyBP-C can trigger the development of HCM. This mechanical perspective can explain why missense mutations and truncations, which induce full loss of the cMyBP-C tether, converge in similar clinical outcomes.

About Bell Helicopter FCX-001 Concept Aircraft-A Short Review

Bell Helicopter is always preparing beautiful surprises for us, so this year has not been outdone and has revealed its vision of its future aircraft model FCX-001, a true vertical elevator, ment to can climb to high altitudes in a record time, with an enviable dynamics and maneuverability. The first appearance of the new model FCX-001 took place at Heli Expo 2017 in Dallas, Texas, where the new concept of the aircraft was presented in this highly stylized form. The aircraft appeared in the Bell stand, both in the form of a large-scale layout and in the virtual reality by using immersive helmets, the two-engine ship incorporating some of the new technologies currently under development at Bell and it is very likely to mature in the near future. At first glance, you are astonished at a cockpit that is totally devoid of physical controls, as if the ship were to run alone, fully automated. Notable elements in the design of the FCX-001 include a fan-driven anti-torque system, hybrid propulsion system, main rotor blade tips, extensive use of fuselage glass, winged doors and the use of augmented reality in the cockpit to control the aircraft. On the very roomy cabin ceiling of the aircraft, configured for only eight passengers in the Heli-Expo model, but able to adapt up to 12 passengers, Bell introduced a drop-down control module to allow personalization maximum and increased passenger comfort. The concept is provided with various modules that provide passengers with the ability to adjust their own things, such as cabin light intensity, interior temperature, or infotainment system. When looking closely at the new FCX-001 concept, starting with the back of the aircraft, it does not have a tail rotor (which is essential and notable for Bell's new model). In order to achieve the anti-torque instead, a new multi-rotor system is needed in the hood. It gives the aircraft the ability to push in both directions and also has vector control of the traction, also allowing it to give up a horizontal stabilizer. The anti-torque system is acted by an electric motor as part of a hybridized propulsion system. At the top of the aircraft, the main rotor blades (morphing) have an attractive design. At the same time, technology aims to allow the tip of each blade to move between the different flight regimes, just like a swing wing on an airplane to maximize efficiency and performance and reduce noise. The actual airframe of the aircraft is also very different from what Bell used in the past. In terms of ladder, the FCX-001 is slightly larger than a Bell 412 both in terms of its length and width, its new lines and its use of massive glass exhibiting some production challenges that rely on the new composite structures, today so widely used in the aviation and aerospace industries.

Paleoenvironment of deposition of Miocene succession in well BK-10 of Bengal Basin using electrofacies and lithofacies modeling approaches

Integrating well log and core samples data were applied to interpret paleoenvironment of deposition of Miocene succession for understanding of reservoir facies model from a well Bakhrabad (BK)-10 of Bengal Basin. Miocene succession was subdivided into two depositional sequences/models which contain 9 para sequence sets and 35 para sequences. Detailed examination of well log data, based on considering GR (gamma ray) log shapes, size, lithologic variations permit a subdivision into five electrofacies models, e.g., bell, funnel, cylindrical, egg/bow and linear shape models. The succession consists of alternating shales, shaly sand, silts and sandstones, with minor mudstones. The study revealed eight distinct lithofacies models namely, shale dominated facies, heterolithic sandstone facies, cross bedding facies, parallel laminated shale with alternate sand/silt facies, ripple-lamination facies, bioturbation facies, wavy bedded facies and laminated shale facies. The depositional models for the Miocene sediments encountered in the studied well BK-10 inferred to be that of delta-front setting and fluvio-deltaic to shallow marine environments. Based on lithofacies and electrofacies models associations, Miocene succession interpreted as a coarsening upward deltaic progradation; although more repetitive marine transgression and regression sedimentary processes might have an impact on the architecture of reservoir facies model.

Development of a non-destructive bell-tuning technique through optimized structural modifications

Carillons are musical instruments constituted by a set of bells that forms a musical scale encompassing several octaves. For carillons to work in a musically satisfying manner, bell tuners pre-define commonly accepted harmonic relationships between the first five modal frequencies of all bells, typically 0.5:1:1.2:1.5:2 (internal tuning), and a specific target pitch for each bell (external tuning) in order to suit a given musical scale. Currently, bell-tuning is performed by removing metal on the inside of the bell wall. In most cases this process is made empirically, through trial and error, frequently leading to ineffective results. Moreover, this approach can weaken the bell structure and is irreversible, a far from ideal situation in the case of historical carillons. Following our recent work on bar tuning, this paper addresses a non-destructive multimodal tuning method, which consists of attaching suitably designed masses to the bells, in order to comply with the pre-defined set of target frequencies. This is achieved through the combination of dynamical modelling and structural modification techniques with optimization methods, in order to compute the optimal location and magnitude of the tuning masses. First, a full-sized finite element model of a real-life bell is used to compute the modal properties of the original, imperfectly tuned, system. A physical model based on the modal formulation is then built from the modes of the original system, allowing the reduction of the number of equations by several orders of magnitude, compared to the finite element model. This modal formulation is particularly effective for the subsequent iterative optimization process, leading to significant improvements in convergence, as well as computational efficiency. Outcomes from this work attest the effectiveness and robustness of the proposed tuning method and provide encouraging results towards the development of feasible non-destructive methods for bell-tuning.

Textual Architecture of a Selected Hard News in English: A Discourse Analysis Approach

This study deals with the analysis of a selected hard news through the adaptation of an eclectic model of analysis by the use of Van Dijk (1988), Bell (1991) and Halliday (1976) models of discourse analysis. Writing news stories is a problematic process because it is not a process of merely putting words together to form a text or report, but it involves the choice of the words and markers that conditioned by the purpose, place, and the readers. The study aims at proposing a theoretical framework for the macro- level analysis of news discourse. It covers the macro level analysis of the chosen hard news. The data of the study is an English news story taken from Washington Times newspaper published on 20th of August 2016. The results of the study display that English hard news stories show certain complexity in their structure. The writer of this hard news story aims at not only conveying information but arising the voice of protest against the government and the court of justice. Such analysis reaches to a conclusion, which emphasizes the idea that the field of discourse can be used for better understanding of the media.

Assessment of impact of fishing on Indian mackerel Rastrelliger kanagurta (Cuvier, 1816) in Tuticorin, south-east coast of India

Fishery of the Indian mackerel Rastrelliger kanagurta (Cuvier, 1816) from Tuticorin was studied for the period 2011-2014. Indian mackerel formed fishery round the year in Tuticorin with peak during June to November in trawl and October to December in gillnet. The annual catch varied from 1650 to 5101 t (average 2968 t) in gillnet and from 815 to 1716 t (average 1231 t) in trawl. Total length (TL) of the fishes ranged from 10 to 30.5 cm. Length-weight relationship estimated was W = 0.0038777*L3.3 (r2 = 0.99, n = 535, L=TL in cm, W in g). The fishes were found to be continuous spawners with peak spawning during January to August and November. The von Bertalanffy growth equation derived was Lt = 31.2 [1-e -1.3(t+t0)]. The species attained TL of 22.7 cm in 12 months and 28.9 cm by the end of second year. Longevity estimated was 2.3 years, Phi-prime index (ᴓ) was 7.143, while Z and M were 4.36 and 2.132 respectively. Thompson and Bell model showed continuous increase of yield even after considerable rise in F-factor. Spawning stock biomass (SSB) was 79% at an f-factor of 3.5. F0.1 using Beverton and Holt Y/R model was 3.4 whereas the present F was 2.23 indicating that the current level of fishing is not affecting the stock adversely.

Establishment of the Relationship Between Fathers and Premature Infants in Neonatal Units.

Parents and their preterm infants (born between 32-37 weeks of gestation) are often overlooked by the healthcare system. And very little attention is given to the relationship parents develop with their infants in the neonatal unit (NNU). Specifically, very few studies focused on fathers and how they establish a relationship with their infants. However, we know that the father-infant relationship is extremely important for their future social development and more. This article presents the results of a qualitative study of the establishment of the father-premature infant relationship in an NNU. The study's theoretical framework was Bell's model of the parent-infant relationship, which encompasses discovery, physical proximity, communication, involvement, and emotional attachment. Ten fathers of premature infants (gestational age: 32-37 weeks) participated in 2 semistructured interviews (1 individual and 1 "in situ," ie, at the infant's bedside) during the first week following the premature birth. The results confirm the emergence of different components of the relationship between fathers and their children from the first days of hospitalization in the NNU. The commitment component is the basis for the development of other components in the relationship with their children. Furthermore, involvement influences the deployment of emotional attachment, discovery, physical proximity, and communication toward premature infants. Similarly, the 5 themes of the model can be seen as forming a dynamic nexus in which each theme influences the others. For neonatal nurses, this model of the early father-child relationship helps the understanding of the deployment of that relationship according to 5 components. Similarly, it provides awareness of the experiences of fathers so that nurses can be better equipped to support and individualize interventions tailored to their specific needs, thus helping them develop and sustain the relationship with their children. This study allows us to better understand fathers' experience regarding the establishment of the relationship to their premature infants born between 32 and 37 weeks of gestation. However, there is little understanding about the early paternal experience and more research on this dyad is necessary in neonatology.

Investigating the effects of membrane deformability on artificial capsule adhesion to the functionalized surface

Understanding, manipulating and controlling cellular adhesion processes can be critical in developing biomedical technologies. Adhesive mechanisms can be used to the target, pattern and separate cells such as leukocytes from whole blood for biomedical applications. The deformability response of the cell directly affects the rolling and adhesion behavior under viscous linear shear flow conditions. To that end, the primary objective of the present study was to investigate numerically the influence of capsule membrane's nonlinear material behavior (i.e. elastic-plastic to strain hardening) on the rolling and adhesion behavior of representative artificial capsules. Specifically, spherical capsules with radius of [Formula: see text] were represented using an elastic membrane governed by a Mooney-Rivlin strain energy functions. The surfaces of the capsules were coated with P-selectin glycoprotein-ligand-1 to initiate binding interaction with P-selectin-coated planar surface with density of [Formula: see text] under linear shear flow varying from 100 to [Formula: see text]. The numerical model is based on the Immersed Boundary Method for rolling of deformable capsule in shear flow coupled with Monte Carlo simulation for receptor/ligand interaction modeled using Bell model. The results reveal that the mechanical properties of the capsule play an important role in the rolling behavior and the binding kinetics between the capsule contact surface and the substrate. The rolling behavior of the strain hardening capsules is relatively smoother and slower compared to the elastic-plastic capsules. The strain hardening capsules exhibits higher contact area at any given shear rate compared to elastic-plastic capsules. The increase in contact area leads to decrease in rolling velocity. The capsule contact surface is not in complete contact with the substrate because of thin lubrication film that is trapped between the capsule and substrate. This creates a concave shape on the bottom surface of the capsule that is referred to as a dimple. In addition, the present study demonstrates that the average total bond force from the capsules lifetime increases by 37% for the strain hardening capsules compared to elastic-plastic capsules at shear rate of [Formula: see text]. Finally, the model demonstrates the effect of finite membrane deformation on the coupling between hydrodynamic and receptor/ligand interaction.

Decision Principles for Routing Strategies: Games against Nature and Demons

In this paper the authors firstly review general decision principles under uncertainty and apply them to route choice decisions. Risk-averse behaviour leads to the description of route choice a game. The difference between games against demons and nature are pointed out by distinguishing when disruptions on the chosen route might be related to the traveller’s behaviour or not. It is argued that in many cases the traveller has some (limited) information about the connection between attack likelihood and routing, meaning that pure games against demons are rare for practical applications. The paper therefore extends the game theoretic literature on route choice by formulating a generalised model. The model allows for games against multiple demons and consideration that some links might be safer than others. It is shown that games against nature and the Bell (2007) model can be derived as limiting cases. Results are illustrated with an example network.

COMPUTATIONAL DETERMINATION OF THE DETACHMENT TIME OF THE LEUKOCYTE UNDER DIFFERENT KINETIC DISSOCIATION RATE PARAMETERS

Three-dimensional simulation of the leukocyte detachment subjected to blood flow is presented. The initially captured leukocyte is modeled as a sphere adhered to the bottom wall of a cylindrical vessel via receptor/ligand bonds (P-selectin/PSGL-1). Ansys Parametric Design Language is used to create the geometrical model and couple the Navier–Stokes flow solver with structural equations and the Monte Carlo equation to define the stochastic breakage of the bonds. The assumption of equal forces on bonds has been ignored and the force on each bond is obtained from the balance between hydrodynamic forces and cellular viscoelasticity at every time step. In this model, catch-slip behavior of the P-selectin/PSGL-1 is considered by using the two-pathway dissociation model instead of the Bell model to define the rate of dissociation of each bond. Detachment time of the leukocyte is the time elapsed until all the bonds break. The effects of various values of blood inlet velocities, bond stiffness and kinetic properties of the catch bonds on the detachment time of the leukocyte are studied.

Experimental verification of a hybrid dynamical model of the church bell

In this paper we present a hybrid model of church bell. The dynamical system of yoke-bell-clapper is nonlinear and discontinuous. We use the Lagrange equations of the second type to derive formulas that describe the system's motion. The energy between the bell and the clapper is transmitted via impacts, here modeled using a coefficient of energy restitution. The values of the system's parameters have been determined basing on the measurements of the biggest bell ‘‘The Heart of Lodz’’ in the Cathedral Basilica of St Stanislaus Kostka, Lodz, Poland. Using the same bell we also validate the model by comparing the results of numerical simulations with experimental data. The presented results show that the described model is a reliable predictive tool which can be used both to simulate the behavior of the existing yoke-bell-clapper systems as well as to design the yokes and predict the motion of new bells.

单分子拉伸力实验中DNA解链动力学无序效应的介观统计研究

Recent single molecule pulling experiments on DNA unzipping have revealed a heavy-tailed rupture force distribution, indicating dynamic disorder. Here we present a theoretical framework based on a generalized Langevin equation (GLE) with fractional Gaussian noise (fGn) and power-law memory kernel to study the kinetics of DNA unzipping to address the effects of dynamic disorder on barrier-crossing kinetics under external pulling force. Such a GLE-fGn strategy is associated with the slow conformational fluctuations of macromolecules. By using the Kramers rate theory, we have obtained analytical formulae for the time-dependent rate coefficient k ( t , F ), and the distribution of rupture force p ( F ) which demonstrates a fat tail at high force as functions of time t and force F . In addition, through fitting our results to data from single molecule pulling experiments on DNA unzipping, we estimate the kinetic parameters and qualify the extent of disorder. Our work provides a plausible interpretation for the evidence of dynamic disorder in force-induced DNA unzipping, compared to two other models based on Bell model and Langevin equation (LE) approach.

Facial Emotion Recognition and Disorganization in Subjects with Schizophrenia and Alcohol, Substance Use Disorder

Introduction Schizophrenia (SKZ) is a disease characterized by positive and negative symptoms, thoughts and behaviour disorganization with a progressive socio-cognitive impairment 1 ; deficits in facial emotion recognition (FER) represent one of the most serious problems linked to interpersonal problems 2 . In addition, these patients have often comorbid condition of alcohol and substances abuse 3 . Objectives to compare the ability of FER in patients with SKZ using alcohol and/or substances (SKZ+SUD) compared to schizophrenics without SUD (SUD-SKZ). Methods we enrolled 53 subjects (M=40, F=13) with a DSM-IV diagnosis of SKZ (SCID I). The sample was divided according to alcohol and/or substance abuse (AUS and DUS) into two groups, compared for socio-demographic and clinic characteristics (PANSS and Bell model 4 ). We analyzed the association between abuse condition and Ekman test performance. Results SKZ+SUD (n=20; M=16, F=4) and SKZ-SUD (n=33; M=24, F=9) show a statistically significant age difference with a mean (SD) of 38.4 years (10.5) and 46.0 years (8.7) respectively (p=0.006). SKZ+SUD Ekman test score (mean=43.1, SD=6.9) was statistically higher (p=0.006) than SKZ-SUD (mean=34.6, SD=12.0). The different performance was more evident in comparison with poly-abusers (44.94±7.05 vs 12.04±34.6; p=0.002). We further noticed the role of disorganization as a mediator of the relationship between abuse and FER score (p=0.017): the proportion of the effect of abuse on Ekman test score was 48%. Conclusions In subjects with SKZ, FER seems to be less impaired in abusers than non-abusers. We also showed an important role of thoughts and behavioral disorganization as a mediator between SKZ+SUD and FER.

A Smoluchowski Equation for Force-Modulated Chemistry in Single Molecule Pulling Experiments

Thioredoxins (Trx) are a class of enzymes, which catalyze the reduction of disulphide bonds between two cysteine residues, commonly found in proteins. An experimental investigation into the reaction mechanisms employed by various species of Trx was carried out by Perez-Jimenez et al. using single molecule force-clamp spectroscopy. The experiment involved applying a pulling force along the disulfide bond of the protein substrate, and measuring the rate of the Trx-catalyzed reduction as a function of the pulling force. One interesting finding of the experiment was that some forms of thioredoxin exhibit a biphasic relationship for reduction rate as a function of force magnitude. For this project, a mathematical model of this system was created, which employs a Smoluchowski formalism in the vein of Agmon-Hopfied or Sumi-Markus models. The model describes the time evolution of the probability distribution function of the protein's configuration within a space defined as the internal protein coordinate, as it diffuses over a potential which distorts under the applied force, while losing probability density to the Bell model type “sink” term, which is also a function of the applied force, representing reactants going to products (disulphide bond cleavage). By numerically solving the Smoluchowski equation and integrating the resulting surface over both time and the protein coordinate to calculate lifetime for increasing values of applied force, the model successfully reproduced the experimentally observed values for disulphide bond reduction rate as a function of applied force. Parameterizing the Smoluchowski equation to fit the experimentally measured data points provided a means of drawing insights into a physical interpretation of the model including the relationship between degree of biphasic behavior and the distance along the reaction coordinate from the bottom of the reactant well to the top of the transition state.

Involvement of MAPK ERK activation in upregulation of water channel protein aquaporin 1 in a mouse model of Bell's palsy.

The aim of this study is to immunolocalize the aquaporin 1 water channel protein (AQP1) in Schwann cells of idiopathic facial nerve and explore its possible role during the development of facial palsy induced by herpes simplex virus type 1 (HSV-1). HSV-1 was inoculated into the surface of posterior auricle of mouse to establish a paralyzed animal model. In HSV-1-induced facial palsy mice, protein levels of AQP1 significantly increased on the 9th to 16th day after inoculation of HSV-1. The upregulation of AQP1 was closely related to the intratemporal facial nerve edema in facial nerve canal, which was also consistent with the symptom of facial palsy in mice. In a hypoxia model of Schwann cells in vitro, we found that U0126, an ERK antagonist, inhibited not only morphological changes of cultures Schwann cells but also upregulation of both AQP1 and phosphorylated ERK. Combined with increased phosphorylated ERK in HSV-1-induced facial palsy mice, we inferred that ERK MAPK pathway might also be involved in increased AQP1 in mouse model of Bell's palsy. Although the precise mechanism needs to be further explored, our findings suggest that AQP1 in Schwann cells of intratemporal facial nerve is involved in the evolution of facial palsy induced by HSV-1 and may play an important role in the pathogenesis of this disease. AQP1 might be a potential target, and the ERK antagonist U0126 could be a new drug for the treatment of HSV-1-induced Bell's palsy in an early stage.

Factors affecting hydrogen-tunneling contribution in hydroxylation reactions promoted by oxoiron(IV) porphyrin π-cation radical complexes.

Hydrogen atom transfer with a tunneling effect (H-tunneling) has been proposed to be involved in aliphatic hydroxylation reactions catalyzed by cytochrome P450 and synthetic heme complexes as a result of the observation of large hydrogen/deuterium kinetic isotope effects (KIEs). In the present work, we investigate the factors controlling the H-tunneling contribution to the H-transfer process in hydroxylation reaction by examining the kinetics of hydroxylation reactions at the benzylic positions of xanthene and 1,2,3,4-tetrahydronaphthalene by oxoiron(IV) 5,10,15,20-tetramesitylporphyrin π-cation radical complexes ((TMP(+•))Fe(IV)O(L)) under single-turnover conditions. The Arrhenius plots for these hydroxylation reactions of H-isotopomers have upwardly concave profiles. The Arrhenius plots of D-isotopomers, clear isosbestic points, and product analysis rule out the participation of thermally dependent other reaction processes in the concave profiles. These results provide evidence for the involvement of H-tunneling in the rate-limiting H-transfer process. These profiles are simulated using an equation derived from Bell's tunneling model. The temperature dependence of the KIE values (k(H)/k(D)) determined for these reactions indicates that the KIE value increases as the reaction temperature becomes lower, the bond dissociation energy (BDE) of the C-H bond of a substrate becomes higher, and the reactivity of (TMP(+•))Fe(IV)O(L) decreases. In addition, we found correlation of the slope of the ln(k(H)/k(D)) - 1/T plot and the bond strengths of the Fe═O bond of (TMP(+•))Fe(IV)O(L) estimated from resonance Raman spectroscopy. These observations indicate that these factors modulate the extent of the H-tunneling contribution by modulating the ratio of the height and thickness of the reaction barrier.

Single Lipid Extraction: The Anchoring Strength of Cholesterol in Liquid-Ordered and Liquid-Disordered Phases

Cholesterol is important for the formation of microdomains in supported lipid bilayers and is enriched in the liquid-ordered phase. To understand the interactions leading to this enrichment, we developed an AFM-based single-lipid-extraction (SLX) approach that enables us to determine the anchoring strength of cholesterol in the two phases of a phase-separated lipid membrane. As expected, the forces necessary for extracting a single cholesterol molecule from liquid-ordered phases are significantly higher than for extracting it from the liquid-disordered phases. Interestingly, application of the Bell model shows two energy barriers that correlate with the head and full length of the cholesterol molecule. The resulting lifetimes for complete extraction are 90 s and 11 s in the liquid-ordered and liquid-disordered phases, respectively. Molecular dynamics simulations of the very same experiment show similar force profiles and indicate that the stabilization of cholesterol in the liquid-ordered phase is mainly due to nonpolar contacts.