Mutations in the genes for amyloid precursor protein (APP) and presenilins (PS1, PS2) increase production of β-amyloid 42 (Aβ ) cause familial Alzheimer's disease (FAD). Transgenic mice that express FAD mutant APP PS1 overproduce Aβ exhibit plaque pathology similar to found AD, but most transgenic models develop plaques slowly. To accelerate development investigate effects very high cerebral levels, we generated APP/PS1 double coexpress five mutations (5XFAD mice) additively production....

β-Site amyloid precursor protein cleaving enzyme 1 (BACE1) (β-secretase) initiates generation of β-amyloid (Aβ), which plays an early role in Alzheimer's disease (AD). BACE1 levels are increased postmortem AD brain, suggesting elevation promotes Aβ production and AD. Alternatively, the increase may be epiphenomenon late-stage To distinguish between these possibilities, we analyzed using a highly specific antibody, BACE-Cat1, made BACE1−/− mice, mount robust anti-BACE1 immune response....

The absorption spectrum of gaseous fluoride ion has been observed in shock-heated vapors CsF, RbF, and KF. is a continuum with two sharp thresholds at 3595 3542 Å, similar to those the other halide ions. electron affinity determined from low-energy threshold 3.448±0.005 eV. cross-section for photodetachment 3565 Å about 2.5±2×10−18 cm2 3525, 3.3±2×10−18 cm2. affinities chlorine, bromine iodine are revised, respectively, 3.613, 3.363, 3.063 eV, all uncertainties 0.003

A general formal theory is developed for the autoionization of molecules at energies within a few electron volts or less threshold, specifically to include effects interaction an excited Rydberg with rotating, vibrating molecule—ion which it bound. The dominant coupling mechanism involves conversion vibrational energy electronic and most efficient when core can undergo single quantum jump. number simplifications approximations are discussed. Some these used in application H2. Autoionization...

The nonrelativistic differential cross sections for photo-ionization of molecules are derived and worked out in detail systems with random orientation. more important contributions due to electric dipole, quadrupole, magnetic two-photon (nonresonant) absorption have been included. Processes such as vibrationally induced auto-ionization discussed. significance these results regard the design interpretation experiments is also considered. angular distribution photoelectrons from...

A model is presented for the melting and freezing behavior of finite clusters. The has property---and suggests that some real clusters may so behave---that rigid, solidlike form only thermodynamically stable below a "freezing" temperature ${T}_{f}$, coexist with nonrigid, liquidlike within sharply-bounded range temperatures between ${T}_{f}$ higher "melting" ${T}_{m}$, above cluster stable. ${T}_{m}$ are functions $N$, number particles in cluster; it suggested traditional point common to...

We explore the distance fluctuation criterion (“Lindemann criterion”) for melting transitions. Distances from average positions in accord with Lindemann, or interparticle distances, Jellinek and Berry Etters Kaelberer, are examined. The primary goal is to determine which of these offers more useful criterion. choice origin can sometimes effect significance index. study three systems two kinds potentials. They all composed 64 particles: (a) (b), a homopolymer cluster that consist beads...

Multidimensional potential energy surfaces for systems larger than about 15 atoms are so complex that interpreting their topographies and the consequent dynamics requires statistical analyses of minima saddles. Sequences minimum-saddle-minimum points provide a characterization such surfaces. Two examples, Ar 19 (KCI) 32 , illustrate how govern tendencies to form glasses or “focused” structures, example, crystals folded proteins. Master equations relate dynamics. The balance between...

Radiationless transitions in isolated molecules are examined from the point of view breakdown Born–Oppenheimer approximation and nature decay coherently excited states. The problem intramolecular vibronic coupling between zero-order states an molecule seems amenable now to a new approach both terms interpretation experimental investigation. We have classified exhibiting mixing into two extreme cases, which we call resonant case statistical case, characterized by low high densities molecular...

A comparison is made of the applicability two limiting models for describing mobility excess charges in molecular organic solids. Anthracene principal solid examined, but similar calculations are also given naphthalene. critical re-evaluation transfer integrals (which have been calculated from orbital wavefunctions), and an approximate method by which one may include effects electronic polarization. These then used to discuss mobilities (1) terms simple band theory, a delocalized,...

A treatment is developed to interpret the observation that in corresponding regions of ultraviolet absorption spectra sodium iodide and potassium show a band system continuum, respectively. The former results from bound excited state which form electronic wave function changes drastically with internuclear distance. latter arises because nuclear motion can no longer be considered adiabatic respect motion, so noncrossing rule does not apply.

Aliphatic N-oxides as cosolvents with water play an important role in stabilizing and destabilizing the structure of biopolymers such cellulose proteins. To allow for detailed microscopic investigations, empirical force field to be used molecular simulations is developed two N-oxide species, N,N,N-trimethylamine-N-oxide (TMAO) N-methylmorpholine-N-oxide (NMMO). The intra- intermolecular parametrized mainly on basis quantum-chemical calculations tested against available experimental...

Approximate partition functions are constructed from approximate quantum mechanical models of near-rigid, solidlike and nonrigid, liquidlike clusters. The Helmholtz free energies evaluated for these clusters as temperature T cluster size N. thermodynamic temperatures melting, at which the two forms equal, match well with melting determined classical simulations Ar Moreover, effective coexistence ranges solid- approximately same range ‘‘supercooling’’ ‘‘superheating’’ found in molecular...

Configuration-interaction wave functions are calculated for all intrashell doubly excited states of the $N=2$ shell He and isoelectronic ions ${\mathrm{Li}}^{+}$, ${\mathrm{Be}}^{2+}$, ${\mathrm{Ne}}^{8+}$ with use a basis Sturmian functions. The density function $\ensuremath{\rho}({r}_{1},{\ensuremath{\theta}}_{12}|{r}_{2}=\ensuremath{\alpha})$, which is conditional probability that one electron will be found at distance ${r}_{1}$ from nucleus interelectronic angle...

The primary dissociation step for alkali halide diatomics in argon has been studied order to determine whether collisional produces ions, atoms, or a mixture of both types products. method is based on time-resolved absorption spectroscopy shock-heated vapors. Results show that the cesium halides, and rubidium potassium with exception two iodides, dissociate essentially completely ions; lithium salts NaI NaBr atoms; other halides (KI, RbI, NaCl, probably NaF) mixtures atoms at least under...

Vibrationally induced autoionization and one class of predissociation electronically excited ${\mathrm{H}}_{2}$ its isotopes are treated by a perturbed-stationary-state theory. Autoionization rates given for number states ${\mathrm{H}}_{2}$, HD, ${\mathrm{D}}_{2}$. In addition to direct bound-continuum coupling, consideration is effects higher-order coupling; these cause order-of-magnitude changes in isolated cases. The auto-ionization vary with principal quantum $n$ as...

A general formalism is described for treating diabatic coupling processes in highly excited molecular states. The method treats electronic and nuclear motion quantum mechanically, uses the adiabatic Born-Oppenheimer states as basis function. present paper concentrates on diagnoses of vibronic matrix elements, with Rydberg continuum ${\mathrm{H}}_{2}$ test cases. principal contributions come from electron's interactions oscillating finite monopole ion-molecule core. factors transition...

We report a study of the thermodynamic properties indium clusters on $\mathrm{SiN}{}_{x}$ surface during early stages thin film growth using sensitive nanocalorimetry technique. The measurements reveal presence abnormal discontinuities in heat melting below $100\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$. These discontinuities, for which temperature separation corresponds to spatial periodicity equal thickness an monolayer, are found be related atomic ``magic numbers,'' i.e., number atoms...

A statistically based characterization of the topography a multidimensional potential surface classifies not only local minima and saddles but entire basins containing many minima, divides separating monotonic sequences within each basin. The data fold readily into formalisms chemical kinetic isomerization theory master equations to provide connection between that dynamics on surface. This analysis permits an interpretation glass-forming or ``focusing'' character method is illustrated with...

A statistically based method of characterizing the topography a multidimensional potential surface classifies not only local minima and saddles but entire basins containing many minima, divides separating monotonic sequences within each basin. The data, so classified, fold readily into formalisms chemical kinetic isomerization theory master equations to provide connection between that dynamics on surface. This analysis, in particular, permits an interpretation glass-forming or ‘‘focusing’’...