Practical choice of ¹H-¹H decoupling schemes in through-bond ¹H-{X} HMQC experiments at ultra-fast MAS

Three (1)H-(1)H homonuclear dipolar decoupling schemes for (1)H indirect detection measurements at very fast MAS are compared. The sequences require the following conditions: (i) being operable at very fast MAS, (ii) a long T(2)(') value, (iii) a large scaling factor, (iv) a small number of adjustable parameters, (v) an acquisition window, (vi) a low rf-power requirement, and (vii) a z-rotation feature. To satisfy these conditions a modified sequence named TIlted Magic-Echo Sandwich with zero degree sandwich pulse (TIMES(0)) is introduced. The basic elements of TIMES(0) consist of one sampling window and two phase-ramped irradiations, which realize alternating positive and negative 360° rotations of (1)H magnetization around an effective field tilted with an angle θ from the B(0) axis. The TIMES(0) sequence benefits from very large chemical shift scaling factors at ultra-fast MAS that reach κ(cs)=0.90 for θ=25° at ν(r)=80kHz MAS and only four adjustable parameters, resulting in easy setup. Long κ(cs)T(2)(') values, where T(2)(') is a irreversible proton transverse relaxation time, greatly enhance the sensitivity in (1)H-{(13)C} through-bond J-HMQC (Heteronuclear Multiple-Quantum Coherence) measurements with (1)H-(1)H decoupling during magnetization transfer periods. Although similar sensitivity can be obtained with through-space D-HMQC sequences, in which (13)C-(1)H dipolar interactions are recoupled, J-HMQC experiments incorporating (1)H-(1)H decoupling benefit from lower t(1)-noise, more uniform excitation of both CH, CH(2) and CH(3) moieties, and easier identification of through-bond connectivities.     

A dual-tuned quadrature volume coil with mixed λ/2 and λ/4 microstrip resonators for multinuclear MRSI at 7 T

In this work, an eight-element by eight-element dual-tuned quadrature volume coil with a mix of capacitor terminated half-wavelength (λ/2) and quarter-wavelength (λ/4) microstrip resonators is proposed for multinuclear magnetic resonance imaging/spectroscopy studies at 7 T. In the proton channel, λ/2 microstrip resonators with capacitive terminations on both ends are employed for operation at higher frequency of 298.1 MHz; in the heteronucleus channel, capacitor-terminated λ/4 resonators, suitable for low frequency operations, are used to meet the low frequency requirement. This mixed structure design is particularly advantageous for high field heteronuclei magnetic resonance applications with large difference in Larmor frequency of the nuclei in question. The proposed design method makes it much easier to perform frequency tuning for heteronucleus channel using a variable capacitor with a practical capacitance range. As an example, a dual-tuned volume coil for (1)H/(13)C mouse spectroscopic imaging was proposed to demonstrate the feasibility of this method. The finite-difference time-domain method is first used to model this dual-tuned volume coil and calculate the B(1) field distributions at two frequencies. Transmission parameters (S(21)) measured between the proton channel and the carbon channel are -50 dB at 75 MHz and -35 dB at 298 MHz, showing the excellent isolation between the two channels at 7 T. The proton image and (13)C FIDCSI image of a corn oil phantom on the axial plane at 7 T demonstrate the feasibility of the proposed method. A preliminary proton image of a mouse on the sagittal plane is also acquired using the proposed dual-tuned volume coil at 7 T, illustrating a fairly uniform B(1) field and sufficient image coverage for imaging in mice.     

A high resolution FTIR spectroscopic study of the hydrogen-bonded heterodimer H3N−HCN

The spectrum of the symmetric top, hydrogen-bonded heterodimer H₃N?HCN has been recorded between 2900 and 3200cm^?1 using a high resolution FTIR spectrometer. The more intense bands are associated with the ν₂ (H?CN stretch) vibration and include hot bands associated with the low frequency modes ν₅, ν₂ and ν₁₀. Weaker difference bands of the type ν₂+(n?1) ν5?nν₅ are also observed. Analysis of the bands yields values for the band origins: ν2/0=3110·5±0·2cm^?1 and ν5/0=140±5cm^?1 and the anharmonicity constants: x _2,10=12·7±0·5cm^?1, x _2,9≈x _2,5=23±3cm^?1 and x _5,10=?5±2cm^?1. The lifetime in ν₂ with respect to vibrational predissociation, estimated from the width of the sharpest observed feature, is 100?200 ps but there is some indication that this lifetime may decrease at high J.     

A Fast Algorithm for the First-Passage Times of Gauss-Markov Processes with Hölder Continuous Boundaries

Even for simple diffusion processes, treating first-passage problems analytically proves intractable for generic barriers and existing numerical methods are inaccurate and computationally costly. Here, we present a novel numerical method that is faster and has more tightly controlled accuracy. Our algorithm is a probabilistic variant of dichotomic search for the computation of first passage times through non-negative homogeneously Hölder continuous boundaries by Gauss-Markov processes. These include the Ornstein-Uhlenbeck process underlying the ubiquitous “leaky integrate-and-fire” model of neuronal excitation. Our method evaluates discrete points in a sample path exactly, and refines this representation recursively only in regions where a passage is rigorously estimated to be probable (e.g. when close to the boundary).As a result, for a given temporal accuracy in the location of the first passage time, our method is orders of magnitude faster than direct forward integration such as Euler or stochastic Runge-Kutta schemata. Moreover, our algorithm rigorously bounds the probability that such crossings are not true first-passage times.     

Molecular potential energy surface constructed from ab initio interpolation for HCN− + H reaction and deuterated analogues

A classical study for constructing potential energy surface from ab initio electronic energy of molecular fragments was presented for HCN^? + H reaction and deuterated analogues. The classical trajectory was studied on this surface to determine the reaction probability. Reaction probability was used to calculate others observable properties like rate constant and cross section. Rate constants expressions were reported for all reactions. Influence of translation energy of fragments on the reaction probability and reaction cross section was also studied. Nonlinear least-squares fitting was also used to calculate the rate constants expressions. Deuterium was used instead of hydrogen atom to observe the effect of mass of attacking atoms and target molecule on the reaction probability and reaction rate.     

A measure for non-stationarity with applications to gearbox noise

From the evolutionary vector deacription of slowly sime-varyingnoise process,a measure for non-stationarity is developed.It includesboth the non-stationarities of power and of spectrum shape.As a singleparameter,it is a comparable quantity for different processes.Applicationto the analysis of precise gearbox is prescnted.     

Cooling-down of thermal thick probes after flash excitation – A measure for the real energy density?

Though flash lamps are one of the most applied heat sources in the field of Thermographic Testing (TT) using active thermography, only little is known about the actually achieved energy input into test objects. In this paper, an easy to realize sensor concept is proposed and experimentally evaluated. The concept is based on the measurement of the surface temperature of a thermal thick probe after flash excitation. After considering the sensor concept with FEM simulations the experimental investigation of four materials (two polymer and two building materials) is described. It will be shown that a suited coating is essential for the realization of the sensor concept. The experimental results prove the suitability of black rigid PVC as the most promising material. Using a coated PVC sample the energy density of short laser pulses, similar to flashes of flash lamps, could be determined exactly with an estimated relative uncertainty of only a few percent.     

A Procedure for Modelling Shallow Dislocation Sources with Tensional Component

The source terms of a tensile dislocation are presented in terms of the wavenumber and circular frequency.Expressions for displacements on the surface of a half-space due to an arbitrary oriented dislocation are also obtained by using the generalized ray method.The result shows that the far-field waveforms contributed by tensile source are different from other sources.Considering that not all large earthquakes can be explained with the shear dislocation model,these expressions may be efficient in analysing some earthquakes.     

A Simple Method for Measuring Tensile Force with Piezoelectric Patch

We propose a simple method for monitoring the axial tensile and compressive force in a structure by using a piezoelectric patch with the piezoelectric impedance based measurement. A simple approximate equation for estimating the tensile force in two different conditions, which can be calculated easily if the naturM frequencies in two different states are measuredt is explained in detail. On another front, the natural frequency can be very easily measured by a piezoelectric element by bonding it on the measuring subject structure, because its electric impedance of piezoelement is related to the structural mechanical impedance. Furthermore, an experiment for measuring a tensile force in a simple supported beam is carried out for validating the proposed method. The results show a good accuracy in estimating the tensile force variation by the natural frequency change measured from the piezoelement.     

Level densities for nuclei with 47 ≤ A ≤ 59

Nuclear level densities of ⁴⁷V, ⁴⁸V, ⁴⁹V, ⁵³Mn, ⁵⁴Mn, ⁵⁷Co, ⁵⁹Ni and their energy dependences are determined from measurements of the neutron evaporation spectra in the (p, n) reaction. Neutron spectra from the (p, n) reaction on nuclei of ⁴⁷Ti, ⁴⁸Ti, ⁴⁹Ti, ⁵³Cr, ⁵⁴Cr, ⁵⁷Fe, and ⁵⁹Co are measured at proton energies between 7 and 11 MeV. The data are analyzed in terms of statistical equilibrium and pre-equilibrium models of nuclear reactions.     

A text-to-speech system with high intelligibility and naturalness for Chinese

I.IntroductionResearchesonChinesesynthesisdisclosethatonlywhenboththesegmentalandsupraseg-melltalfeaturesofthesyntheticspeecharesimilartothoseofthellaturalone,thesyntheticspeechwillsoundintelligibleandnatural[1].Amongekistingsynthetictechniques,theapproachbasedonacousticparametersca-nadustboththesegmentalandsuprasegmentalfeaturesofsyntheticunitsfiekiblyandcanbeconsideredasthemostreasonablesynthetictechniqueintheory.However,theparameterbasedsynthesizerisoverAfependentonthedevelopmentsofparamet…     

A Modified Mean Field Theory for Spin Systems with Orbital Degeneracy

In order to understand the ground state of spin systems with orbital degeneracy,we present a modified mean-field theory that includes four order parameters.Our mean-field results suggest that for a small Hund interaction,the flavour liquid state is still stable against the solid state,but long-range orders may be attained in the system with sufficient deviation from the SU(4) limit.Finally,the implications for the experimental observations on the system LaMnO3 are discussed.     

A New Method with Sandwiched Composite Films for Encapsulating Flexible OLEDs

We introduce a novel method for sandwiched-composite-film encapsulation that successfully extends the lifetime of flexible organic light-emitting diodes (FOLEDs). The encapsulation layers include two parts: one is a thin multilayer barrier coating, which is made up of two applications of alternating layers composed of a polymer layer (consisting of UV capable resins) and a ceramic layer (consisting of titanium nitride with excellent barrier performance), and the other is a thick polymer film of approximately 70μm in thickness fabricated by a doctor blade onto the thin encapsulation film described above. FOLEDs encapsulated by this novel method have a longer lifetime, and this lifetime is 74 times as much as the lifetime of unencapsulated ones.     

A approach for generating high precision digitaltime-delay with low computational load

I.IntroductionTherearethrcctraditionalmethodsforaccomplishingdigitaldc1ay:over-sampling,digital(time-domain)interpo1ation['landfrcquencydomain1inearphaseweightingt'l.Theircommonshortcomingisthattheycannotprovideprecisede1aywhichmaybccontinuouslyvaried.Inotherwords,thebasicprincipleoftheabovemethodsisdelayquantization,i.c.,thediscretede-layratherthanthccontinuousdclay.Inordcrtoobtainthenccdedpreciscde1ay,moreopcra-hons,hardwareandsoftwarearenccded,nomattertheimp1ementationisinthetimedomainorfr…     

A novel technique for wireless optical communications with lenslet array processor

A novel communication technique is proposed, which utilizes a set of mutually distinguishable optical patterns instead of convergent facula to transmit information. Then the capacity is increased by exploiting the optical spatial bandwidth resources. At last, we experimentally demonstrate the proposed communication technique based on four 8×8 spatial pattern signals by using lenslet array processor.     

A Bijection Theorem for Domino Tilings with Diagonal Impurities

We consider the dimer problem on a planar non-bipartite graph G, where there are two types of dimers one of which we regard as impurities. Computer simulations reveal a reminiscence of the Cheerios effect, that is, impurities are attracted to the boundary, which is the motivation to study this particular graph. Our main theorem is a variant of the Temperley bijection: a bijection between the set of dimer coverings and the set of spanning forests with certain conditions. We further discuss some implications of this theorem: (1) the local move connectedness yielding an ergodic Markov chain on the set of all possible dimer coverings, and (2) a rough bound for the number of dimer coverings and that for the probability of finding an impurity at a given edge, which is an extension of a result in (Nakano and Sadahiro in ).     

A Resonance Theory for Open Quantum Systems with Time-Dependent Dynamics

We develop a resonance theory to describe the evolution of open systems with time-dependent dynamics. Our approach is based on piecewise constant Hamiltonians: we represent the evolution on each constant bit using a recently developed dynamical resonance theory, and we piece them together to obtain the total evolution. The initial state corresponding to one time-interval with constant Hamiltonian is the final state of the system corresponding to the interval before. This results in a non-Markovian dynamics. We find a representation of the dynamics in terms of resonance energies and resonance states associated to the Hamiltonians, valid for all times t≥0 and for small (but fixed) interaction strengths. The representation has the form of a path integral over resonances. We present applications to a spin-fermion system, where the energy levels of the spin may undergo rather arbitrary crossings in the course of time. In particular, we find the probability for transition between ground- and excited state at all times.     

A combined error calibration technique with experiment for frequency-space spectrum estimation

1 IntroductionDirection-finding technique based on the characteristic-value decompose of array covariancematrix is sensitive to the model errors and makes it difficult to realize a precise system. Themodel errors are dominatly composed of chan-nel ndsmatching, sensor coupling and locationerror. And each of them will bring great affection to the whole system. Some analyses of theseaspects have beed made ajnd a few results attai.ed[1--ic]. But all of these methods are basedon traditional MUSI…