In vivo multimode Raman imaging reveals concerted molecular composition and distribution changes during yeast cell cycle

In vivo time-lapse Raman imaging reveals highly dynamic and concerted changes in concentration and distribution of phospholipids and proteins during and after cell division of a single living Schizosaccharomyces pombe cell.     

Surface abundance change in vacuum ultraviolet photodissociation of CO2 and H2O mixture ices

Photodissociation of amorphous ice films of carbon dioxide and water co-adsorbed at 90 K was carried out at 157 nm using oxygen-16 and -18 isotopomers with a time-of-flight photofragment mass spectrometer. O((3)P(J)) atoms, OH (v = 0) radicals, and CO (v = 0,1) molecules were detected as photofragments. CO is produced directly from the photodissociation of CO(2). Two different adsorption states of CO(2), i.e., physisorbed CO(2) on the surface of amorphous solid water and trapped CO(2) in the pores of the film, are clearly distinguished by the translational and internal energy distributions of the CO molecules. The O atom and OH radical are produced from the photodissociation of H(2)O. Since the absorption cross section of CO(2) is smaller than that of H(2)O at 157 nm, the CO(2) surface abundance is relatively increased after prolonged photoirradiation of the mixed ice film, resulting in the formation of a heterogeneously layered structure in the mixed ice at low temperatures. Astrophysical implications are discussed.     

A theoretical and experimental study on translational and internal energies of H2O and OH from the 157 nm irradiation of amorphous solid water at 90 K

The photodesorption of H(2)O in its vibrational ground state, and of OH radicals in their ground and first excited vibrational states, following 157 nm photoexcitation of amorphous solid water has been studied using molecular dynamics simulations and detected experimentally by resonance-enhanced multiphoton ionization techniques. There is good agreement between the simulated and measured energy distributions. In addition, signals of H(+) and OH(+) were detected in the experiments. These are inferred to originate from vibrationally excited H(2)O molecules that are ejected from the surface by two distinct mechanisms: a direct desorption mechanism and desorption induced by secondary recombination of photoproducts at the ice surface. This is the first reported experimental evidence of photodesorption of vibrationally excited H(2)O molecules from water ice.     

Operation of micro and molecular machines: a new concept with its origins in interface science

A landmark accomplishment of nanotechnology would be successful fabrication of ultrasmall machines that can work like tweezers, motors, or even computing devices. Now we must consider how operation of micro- and molecular machines might be implemented for a wide range of applications. If these machines function only under limited conditions and/or require specialized apparatus then they are useless for practical applications. Therefore, it is important to carefully consider the access of functionality of the molecular or nanoscale systems by conventional stimuli at the macroscopic level. In this perspective, we will outline the position of micro- and molecular machines in current science and technology. Most of these machines are operated by light irradiation, application of electrical or magnetic fields, chemical reactions, and thermal fluctuations, which cannot always be applied in remote machine operation. We also propose strategies for molecular machine operation using the most conventional of stimuli, that of macroscopic mechanical force, achieved through mechanical operation of molecular machines located at an air-water interface. The crucial roles of the characteristics of an interfacial environment, i.e. connection between macroscopic dimension and nanoscopic function, and contact of media with different dielectric natures, are also described.     

Ab initio theoretical calculations of the electronic excitation energies of small water clusters

A direct ab initio molecular dynamics method has been applied to a water monomer and water clusters (H(2)O)(n) (n = 1-3) to elucidate the effects of zero-point energy (ZPE) vibration on the absorption spectra of water clusters. Static ab initio calculations without ZPE showed that the first electronic transitions of (H(2)O)(n), (1)B(1)←(1)A(1), are blue-shifted as a function of cluster size (n): 7.38 eV (n = 1), 7.58 eV (n = 2) and 8.01 eV (n = 3). The inclusion of the ZPE vibration strongly affects the excitation energies of a water dimer, and a long red-tail appears in the range of 6.42-6.90 eV due to the structural flexibility of a water dimer. The ultraviolet photodissociation of water clusters and water ice surfaces is relevant to these results.     

Exact ground-state correlation functions of one-dimensional strongly correlated electron models with resonating-valence-bond ground state

We investigate one-dimensional strongly correlated electron models which have the resonating-valence-bond state as the exact ground state. The correlation functions are evaluated exactly using the transfer matrix method for the geometric representations of the valence-bond states. In this method, we only treat matrices with small dimensions. This enables us to give analytical results. It is shown that the correlation functions decay exponentially with distance. The result suggests that there is a finite excitation gap, and that the ground state is insulating. Since the corresponding noninteracting systems may be insulating or metallic, we can say that the gap originates from strong correlation. The persistent currents of the present models are also investigated and found to be exactly vanishing.     

Out of Equilibrium Dynamics of the Toy Model with Mode Coupling and Trivial Hamiltonian

We extend our previous analysis of the toy model that mimics the mode coupling theory of supercooled liquids and glass transitions to the out of equilibrium dynamics. We derive a self-consistent set of equations for correlation and response functions.     

Palladium(O)-catalyzed allylic alkylation and amination of allylic phosphates

Allyl diethyl phosphates (1) can be easily substituted with malonates and amines in the presence of palladium(O) catalyst. Synthetic utility of the reaction is demonstrated by the sequential amination-amination and alkylation-amination of (Z)-4-acetoxybut-2-enyl diethyl phosphate (1b) with high regio- and stereoselectivity.     

Field desorption mass spectrometry of natural products—I: Steroid- and triterpene saponins

Field desorption mass spectra of underivatized oligoglycosides of spirostanol and its congeners and of hederagenin revealed the molecular weight and structural information. The basic predominance of the formation of stable ions of highly polar natural products (with 5–17 free OH functions) is clearly demonstrated. After the extraction and purification procedure from plant material the samples contained inorganic salts in concentrations between 0.01 and 0.1%. These salt impurities, mostly alkali halides, strongly promoted the attachment of alkali cations to the intact molecules and their fragments. The ions produced gave analytical information not only for the confirmation of the molecular weight but also for the identity of the aglycone and, to some extent, for the sequence of the sugars in the oligoglycosides. All spectra were recorded on photoplates at a resolution of better than 15000 and enabled the evaluation of the elemental composition of the ions generated. The drawbacks and merits of integrating ion recording using the photoplate for FD investigations of highly polar substances are discussed.