Energy transfer from adenosine triphosphate

We suggest a direct molecular mechanism of energy transfer from adenosine triphosphate (ATP) in hydrolysis and phosphorylation reactions, from chemical energy into mechanical energy. Upon hydrolysis of ATP, say bound to a protein, the electrostatic energy of Coulombic repulsion of the ions adenosine diphosphate and phosphate is available to assert a force on a neighboring molecular group in the protein and can do work on that group, or as the ions recede from each without asserting such a force, they gain relative kinetic energy, which, in the absence of dissipative collisions that turn this kinetic energy into heat, can be converted into any other form of energy and work by an impulse, a collision with a neighboring group, without restrictions. Either possibility can be used as a source of activation energy for reactions, as a source of energy to surmount energy barriers in conformational changes, and as a source of work to be done, as in muscle. In some systems where the Gibbs free energy change is fully utilized, all of this energy is turned into mechanical energy, and we suggest a similar mechanism. From the literature we cite some experimental evidence and several quotations indicative of the possibility of our suggestion.     

外电场下氮化铝分子结构和光谱研究

以6-311＋G(2DF)为基函数, 采用密度泛函B3P86的方法研究了外电场作用下氮化铝(AlN)基态分子的几何结构、HOMO能级、LUMO能级、能隙及谐振频率. 结果表明, 外电场的大小和方向对AlN分子基态的这些性质有明显影响. 在所加的电场范围内, 随着外电场的增大分子键长减小, 谐振频率增大, 总能量升高, 在F＝0.02 a.u.时能量达到最大, 为－297.4217 a.u., 此后继续增大电场强度, 系统总能量则开始降低; EH 和EL 随着电场的增加均逐渐增大, 在 F＝0.01 a.u.时, EH 和EL均取得最大值, 分别为－0.2776和－0.0828 a.u., 随着电场的继续增大, 能级EH和EL均逐渐减小, 而能隙在外电场增大的过程中始终处于减小趋势.     

Energy transfer of highly vibrationally excited naphthalene. I. Translational collision energy dependence

Energy transfer between highly vibrationally excited naphthalene and Kr atom in a series of translational collision energies (108-847 cm(-1)) was studied separately using a crossed-beam apparatus along with time-sliced velocity map ion imaging techniques. Highly vibrationally excited naphthalene in the triplet state (vibrational energy: 16,194 cm(-1); electronic energy: 21,400 cm(-1)) was formed via the rapid intersystem crossing of naphthalene initially excited to the S(2) state by 266 nm photons. The collisional energy transfer probability density functions were measured directly from the scattering results of highly vibrationally excited naphthalene. At low collision energies a short-lived naphthalene-Kr complex was observed, resulting in small amounts of translational to vibrational-rotational (T-->VR) energy transfer. The complex formation probability decreases as the collision energy increases. T-->VR energy transfer was found to be quite efficient at all collision energies. In some instances, nearly all of the translational energy is transferred to vibrational-rotational energy. On the other hand, only a small fraction of vibrational energy is converted to translational energy. The translational energy gained from vibrational energy extend to large energy transfer (up to 3000 cm(-1)) as the collision energy increases to 847 cm(-1). Substantial amounts of large V-->T energy transfer were observed in the forward and backward directions at large collision energies.     

Electron kinetic energies from vibrationally promoted surface exoemission: evidence for a vibrational autodetachment mechanism

We report kinetic energy distributions of exoelectrons produced by collisions of highly vibrationally excited NO molecules with a low work function Cs dosed Au(111) surface. These measurements show that energy dissipation pathways involving nonadiabatic conversion of vibrational energy to electronic energy can result in electronic excitation of more than 3 eV, consistent with the available vibrational energy. We measured the dependence of the electron energy distributions on the translational and vibrational energy of the incident NO and find a clear positive correlation between final electron kinetic energy and initial vibrational excitation and a weak but observable inverse dependence of electron kinetic energy on initial translational energy. These observations are consistent with a vibrational autodetachment mechanism, where an electron is transferred to NO near its outer vibrational turning point and ejected near its inner vibrational turning point. Within the context of this model, we estimate the NO-to-surface distance for electron transfer.     

Comparison of energy‐loss functions from REELS spectra with surface and bulk energy loss functions for Ag

Effective energy‐loss functions were derived from the reflection electron energy‐loss spectroscopy (REELS) spectra of Ag by an extended Landau approach. The effective energy‐loss functions obtained are close to the surface energy‐loss function in the low‐energy‐loss region, but tend to be closer to the bulk energy‐loss function in the higher energy‐loss region for higher primary energy. The REELS spectra incorporating the effective energy‐loss function are also reproduced in a Monte‐Carlo simulation model and confirm that the simulation reproduces the experimental REELS spectra with considerable success. Copyright © 2003 John Wiley & Sons, Ltd.     

Surface induced dissociation of chromium hexacarbonyl on fluorinated alkanethiolate surface in ion cyclotron resonance mass spectrometer: studies of energetics of the process using recursive internal energy distribution search method

Energy transfer in ion-surface collisional activation is characterized for 0–30 eV collisions of chromium hexacarbonyl molecular cations with a monolayer of fluorinated alkanethiolate self-assembled onto a solid gold surface. This surface was mounted on the back trapping plate of the Infinity® cell of a Bruker BioApex 7T ion cyclotron resonance mass spectrometer on the B-field axis orthogonal to the ion beam direction. Internal energy deposition was deduced from fragmentation spectra using a recursive internal energy distribution search method. The efficiency of energy transfer into the ion slowly increases with incident ion energy to a maximum value of 20% at about 23 eV collision energy. Approximate kinetic energy distributions of the fragments were measured by deducing the dependence of ion abundance on trapping potential. From the kinetic energy dependence on mass we infer that rapid decomposition of the molecular cation occurs after it recoils from the surface. Knowledge of both internal and kinetic energy distributions of collisionally activated ions enabled us to deduce the energy deposited into the self-assembled monolayer as a function of collision energy.     

精确固定节面量子Monte：Carlo差值法

本文提出了精确固定节面量子Monte Carlo差值法，这个新算法能够在精确固定节面量子Monte Carlo方法的基础上直接计算两个体系之间的能量差，且使计算结果的统计误差达到10-2 kJ/mol 数量级，获得电子相关能90%以上。我们把这个新算法应用于分子势能面的研究中，使用一个“刚性移动”模型，利用Jacobi变换使分子两个几何构型的能量计算具有很好的正相关性，因而能得到准确的能量差值，于是精确的分子势能面就可以得到。这个新算法已经被使用到BH分子基态势能曲线和H₃分子势能面的研究。这个算法还可应用于分子光谱、化学反应能量变化值等领域的研究。     

The divide-expand-consolidate family of coupled cluster methods: numerical illustrations using second order Møller-Plesset perturbation theory

Previously, we have introduced the linear scaling coupled cluster (CC) divide-expand-consolidate (DEC) method, using an occupied space partitioning of the standard correlation energy. In this article, we show that the correlation energy may alternatively be expressed using a virtual space partitioning, and that the Lagrangian correlation energy may be partitioned using elements from both the occupied and virtual partitioning schemes. The partitionings of the correlation energy leads to atomic site and pair interaction energies which are term-wise invariant with respect to an orthogonal transformation among the occupied or the virtual orbitals. Evaluating the atomic site and pair interaction energies using local orbitals leads to a linear scaling algorithm and a distinction between Coulomb hole and dispersion energy contributions to the correlation energy. Further, a detailed error analysis is performed illustrating the error control imposed on all components of the energy by the chosen energy threshold. This error control is ultimately used to show how to reduce the computational cost for evaluating dispersion energy contributions in DEC.     

Energiebestimmung von Alphateilchen mit Festkörperspurdetektoren

Recently a method using solid state track detectors for the energy determination of alpha-particles has been developed in the Central Institute for Nuclear Research at Rossendorf. The method shows a good accuracy and has an energy resolution which is sufficient for the application in several disciplines. The method is based on a determination of the particle ranges in the detector material. The particle energy can be calculated by the known energy—range relationship. In the energy range from 3 to 6 MeV, which is the energy region of the most alpha-emitters, the energy resolution is 50 keV. The accuracy under optimum conditions is about ±50 keV. The efficiency of the method depends on the particle energy and the energy resolution desired. The method can be used for the energy determination of alpha-particles above 2.7 MeV.     

Energy transfer of highly vibrationally excited phenanthrene and diphenylacetylene

The energy transfer between Kr atoms and highly vibrationally excited, rotationally cold phenanthrene and diphenylacetylene in the triplet state was investigated using crossed-beam/time-of-flight mass spectrometer/time-sliced velocity map ion imaging techniques. Compared to the energy transfer between naphthalene and Kr, energy transfer between phenanthrene and Kr shows a larger cross-section for vibrational to translational (V → T) energy transfer, a smaller cross-section for translational to vibrational and rotational (T → VR) energy transfer, and more energy transferred from vibration to translation. These differences are further enlarged in the comparison between naphthalene and diphenylacetylene. In addition, less complex formation and significant increases in the large V → T energy transfer probabilities, termed supercollisions in diphenylacetylene and Kr collisions were observed. The differences in the energy transfer between these highly vibrationally excited molecules are attributed to the low-frequency vibrational modes, especially those vibrations with rotation-like wide-angle motions.     

Energy transfer of highly vibrationally excited azulene. III. Collisions between azulene and argon

The energy transfer dynamics between highly vibrationally excited azulene molecules (37 582 cm(-1) internal energy) and Ar atoms in a series of collision energies (200, 492, 747, and 983 cm(-1)) was studied using a crossed-beam apparatus along with time-sliced velocity map ion imaging techniques. The angular resolved collisional energy-transfer probability distribution functions were measured directly from the scattering results of highly vibrationally excited azulene. Direct T-VR energy transfer was found to be quite efficient. In some instances, nearly all of the translational energy is transferred to vibrational/rotational energy. On the other hand, only a small fraction of vibrational energy is converted to translational energy (V-T). Significant amount of energy transfer from vibration to translation was observed at large collision energies in backward and sideway directions. The ratios of total cross sections between T-VR and V-T increases as collision energy increases. Formation of azulene-argon complexes during the collision was observed at low enough collision energies. The complexes make only minor contributions to the measured translational to vibrational/rotational (T-VR) energy transfer.     

Intramolecular and intermolecular energy transfers in donor-acceptor linear porphyrin arrays

We present highly time-resolved spontaneous fluorescence spectra of a porphyrin array system that consists of an energy donor and an acceptor linked by a phenyl group. The donors are meso-meso directly linked zinc(II) porphyrin arrays and the acceptor is a zinc(II) 5,15-di(phenylethynyl)porphyrin. The spectra over the entire Q (S1) emission band following the excitation of the donor B (S2) state have been measured directly without the conventional spectral reconstruction method. The time-resolved fluorescence spectra revealed detailed energy relaxation processes within the donor and subsequent energy transfer to the acceptor. The observed energy transfer rates to the acceptor are consistent with the Forster energy transfer rates calculated on the assumption that the energy is localized in the Q state of each porphyrin unit of the donor prior to the energy transfer. The passage of the energy deposited initially on one porphyrin unit of the donor to the acceptor illustrates a sequence of energy delocalization and localization processes before it finally reaches the acceptor.     

Synergistic approach to improve "alchemical" free energy calculation in rugged energy surface

The authors present an integrated approach to "alchemical" free energy simulation, which permits efficient calculation of the free energy difference on rugged energy surface. The method is designed to obtain efficient canonical sampling for rapid free energy convergence. The proposal is motivated by the insight that both the exchange efficiency in the presently designed dual-topology alchemical Hamiltonian replica exchange method (HREM), and the confidence of the free energy determination using the overlap histogramming method, depend on the same criterion, viz., the overlaps of the energy difference histograms between all pairs of neighboring states. Hence, integrating these two techniques can produce a joint solution to the problems of the free energy convergence and conformational sampling in the free energy simulations, in which lambda parameter plays two roles to simultaneously facilitate the conformational sampling and improve the phase space overlap for the free energy determination. Specifically, in contrast with other alchemical HREM based free energy simulation methods, the dual-topology approach can ensure robust conformational sampling. Due to these features (a synergistic solution to the free energy convergence and canonical sampling, and the improvement of the sampling efficiency with the dual-topology treatment), the present approach, as demonstrated in the model studies of the authors, is highly efficient in obtaining accurate free energy differences, especially for the systems with rough energy landscapes.     

Transfer of photoenergy in pi-conjugated polymers. Two types of photoluminescence that involve energy transfer along a polymer chain

Two types of energy transfer in pi-conjugated polymers have been investigated using time-resolved photoluminescence (PL) techniques: type i, perpendicular-type energy transfer from the 2,3-di(p-tolyl)quinoxaline unit to the pi-conjugated main chain of poly[2,3-di(p-tolyl)quinoxaline-5,8-diyl], and type ii, parallel-type energy transfer from the oligo(pyridine-2,5-diyl) (O-Py) unit to the oligo(selenophene-2,5-diyl) (O-Se) unit in a block-type copolymer of O-Py and O-Se. Both types of energy transfer were very fast with a time constant shorter than approximately 0.1 ns; in particular, the type ii energy transfer took place with a time constant of approximately 5 ps. Both pi-conjugated polymers were considered to contain segments with various effective pi-conjugation lengths, and the energy transfer to the segment with a larger effective pi-conjugation length and a smaller pi-pi* transition energy required a longer transition time. A polarizing film was obtained by utilizing the perpendicular-type energy transfer.     

Electrostatic energy of vacancy formation in crystals of polar molecules

An exact expression is derived for the electrostatic energy of a crystal of polar polarizable molecules containing an unrelaxed vacancy. The energy exceeds twice the electrostatic binding energy per molecule L by a polarization energy term, when changes in dielectric response due to the vacancy are ignored. The electrostatic energy of a molecule at a crystal surface is estimated from surface and bulk polarization energy measurements. It can be as high as 1.5 L. making the electrostatic energy of vacancy formation significantly less than L. the value for non-polarizable molecules. This may help to explain anomalous results for certain plastic crystals.     

Conversion of surface energy and manipulation of a single droplet across micropatterned surfaces

To clarify a driving mechanism for the self-movement of a droplet across hydrophobic textured surfaces in series and to develop applications for a microfluidic device, we report a theoretical model, a microfabrication technique, and experimental measurements. The contact angle of a droplet on a composite surface, the stable surface energy level, and the energy barrier caused by hysteresis were investigated. With increasing patterned density of the microstructure, the contact angle and stable surface energy decreased gradually, but the energy barrier increased. Both the analytical results and the experimental measurements show that the surface energy for a suspended status is greater than that for a collapsed status, which produces increased energy to generate the movement of a droplet. An analysis of interactions between actuation force, resistive force, and viscous force during the motion of a droplet is based on the equilibrium between forces. From the perspective of energy conversion, the difference in surface energy between a higher state and a lower state would drive a single droplet and make it move spontaneously if it could overcome the static friction force resulting from hysteresis and the kinetic friction force under droplet movement. The mean velocity in the present device, measured to be 62.5 mm s (-1), agrees satisfactorily with the theoretical prediction. The model developed for the energy levels enables us to assess the contact mode of a droplet placed on the patterned surface. For a prediction of the transport capability of the designed devices, a theoretical interpretation of the conversion between the surface energy and the kinetic energy of the droplet establishes a criterion that the pattern density of a textured surface should be less than 0.76. The effective rate of energy conversion is estimated to be 20.6%.     

An empirical scheme for evaluating in situ bond energy from MNDO data

The in situ bond energy is evaluated from the resonance integral contribution to energy with a correction term of monatomic energy obtained from MNDO calculation. The sum of the in situ bond energies in a molecule is expected to be equal to its atomization energy. Root-mean-square error of heat of formation calculated from in situ bond energy for seventy nine molecules containing hydrogen, carbon, nitrogen, oxygen, and fluorine amounts to 5.5 kcal/mol. Correlations of in situ bond energy with contributional bond energy, bond dissociation energy, isolated stretching frequency, and bond length are performed and discussed.     

Non‐Radiative Energy Transfer Mediated by Hybrid Light‐Matter States

We present direct evidence of enhanced non‐radiative energy transfer between two J‐aggregated cyanine dyes strongly coupled to the vacuum field of a cavity. Excitation spectroscopy and femtosecond pump–probe measurements show that the energy transfer is highly efficient when both the donor and acceptor form light‐matter hybrid states with the vacuum field. The rate of energy transfer is increased by a factor of seven under those conditions as compared to the normal situation outside the cavity, with a corresponding effect on the energy transfer efficiency. The delocalized hybrid states connect the donor and acceptor molecules and clearly play the role of a bridge to enhance the rate of energy transfer. This finding has fundamental implications for coherent energy transport and light‐energy harvesting.     

高分子链通过机械化学反应的信息、能量协同激发实现化学能直接转换为机械能研究的新进展

机械化学反应是指将化学能与机械能直接相互转换的过程。由于机械化学反应可将化学能和机械能直接相互转换,并且有无污染、无噪音、无废物排放和能量转换高等特点,因而正日趋受到世界各国,尤其是发达国家的关注。信息文明的时代一定会有与之相应的物质和能量与信息状态的转换相伴,掌握信息和使用信息是这个时代发展的必然要求。为此,作者通过对高分子物质激发态的分析,从物质、能量和信息三者协同的角度对机械化学反应的原理进行了探讨,并试图用孤子激发来阐明化学能和机械能相互直接转换的原因。随着高分子合成技术的不断发展,我们有可能通过用机械化学反应的手段来为信息文明的时代找到并提供一种新的能源和能量转换方式,并且有可能会导致新的产业革命。     

Miniaturized Salinity Gradient Energy Harvesting Devices

Harvesting salinity gradient energy, also known as “osmotic energy” or “blue energy”, generated from the free energy mixing of seawater and fresh river water provides a renewable and sustainable alternative for circumventing the recent upsurge in global energy consumption. The osmotic pressure resulting from mixing water streams with different salinities can be converted into electrical energy driven by a potential difference or ionic gradients. Reversed-electrodialysis (RED) has become more prominent among the conventional membrane-based separation methodologies due to its higher energy efficiency and lesser susceptibility to membrane fouling than pressure-retarded osmosis (PRO). However, the ion-exchange membranes used for RED systems often encounter limitations while adapting to a real-world system due to their limited pore sizes and internal resistance. The worldwide demand for clean energy production has reinvigorated the interest in salinity gradient energy conversion. In addition to the large energy conversion devices, the miniaturized devices used for powering a portable or wearable micro-device have attracted much attention. This review provides insights into developing miniaturized salinity gradient energy harvesting devices and recent advances in the membranes designed for optimized osmotic power extraction. Furthermore, we present various applications utilizing the salinity gradient energy conversion.