A new PET fluorescent sensor for Zn

A new Zn²⁺ fluorescent sensor NIDPA, with 1,8-naphthalimide as reporting group and di-2-picolylamine (DPA) as recognizing group, has been synthesized via simple steps. Based on photo-induced electron transfer (PET) mechanism, NIDPA has a five-fold fluorescent enhancement and 10 nm absorption blue-shift under simulated physiological conditions corresponding to the binding of Zn²⁺. Apparent dissociation constant for Zn²⁺ (K_d) is 0.83 nM, and Ca²⁺, Mg²⁺, Fe²⁺, Ni²⁺ and Cr³⁺have little influence on fluorescent enhancement. These results suggest that NIDPA can be used to quantitatively and selectively measure the concentration of Zn²⁺ around sub-nanomolar range.     

A new class of quantum states generated by m-fold application of Bogoliubov＇s transformation

By applying higher powers of the Bogoliubov transformation operator b^{\dagger }=ν^*a+μ^*a^{\dagger } to the two-photon coherent states (or minimum uncertainty squeezed states) we construct a new type of quantum state which we call the generalized excited two-photon coherent states. Analytic expressions for the quantum statistical properties are derived, and through numerical computation the phase space quasi-probability distributions are found. These states can exhibit highly nonclassical behaviour depending on the degree of excitation m and other parameters. For particular values of two parameters λ and ρ, these generalized states reduce to other classes of coherent states formerly reported. Our theory thus presents a much broader approach to these types of quantum states.     

相关哈特曼-夏克波前传感器波前重构新方法

对相关哈特曼-夏克波前传感器的波前重构方法进行了研究,提出了一种基于相邻子图像间相对平移量的波前重构新方法。与常用的基于单一参考子图像的波前重构方法相比,新方法的动态范围有了很大提高。在8×8去4角的子孔径划分下,测量离焦波面时,新方法的动态范围可提高约16倍,子孔径数目越多,动态范围提高的倍数也越高。精度分析表明,两种波前重构方法在8×8去4角的子孔径划分下精度相近,在子孔径数目更多时,相邻子图像处理法的波前重构精度低于单一参考子图像法。     

A new class of ideal clocks

We have found a new class of ideal clocks within general relativity. They are self-gravitating systems such as rotating stars, rotating black holes, and binary star systems. The gravitational red shift of the observed period of rotation of such clocks in a given, weak external gravitational field is shown to be the same as that of an ideal atomic clock. Because the clocks have structure and dynamics determined by gravitational interactions, the full nonlinear machinery of general relativity must be used. This result is important for the binary pulsar PSR 1913+16, where the gravitational red shift of the pulsar's frequency caused by the companion's gravitational field is an observable effect.Supported in part by the National Science Foundation Grant Nos. PHY81-15800 and PHY83-13545.This essay received the third award from the Gravity Research Foundation for 1984-Ed.     

Study of magnetization reversal of Co/Pd bit-patterned media by micro-magnetic simulation

Bit-patterned media based on a single-bit-per-island may be a promising candidate for perpendicular magnetic recording at the Tb/in² level because they could provide a lower noise and higher density. The understanding of magnetization reversal processes in such patterned media is important. In this work, the range of single domain island size based on Co/Pd bit-patterned media was determined. Demagnetization effect, dipolar interactions and switching field distribution (SFD) for bit-patterned media were quantitatively studied by the simulation based on Landau-Lifshitz-Gilbert equation. The total hysteresis loops and SFD were comparable with the experiment ones. The SFD increased from 2σ=1.2 kOe (as the calculated intrinsic SFD) to the experimental value of 1.9 kOe due to dipolar interactions which is in a good agreement with the experimental results (2.0 kOe). Optimized patterned structure with a minimized SFD and maximized data storage densities was found to have an island size of 10 nm and islands separation of 20 nm. The calculated ratio of SFD/H_c (H_c: the coercivity) is 9.2%, which is below the threshold of 10% for 1 Tb/in² pattern media.     

A new subdivision method for grating-based displacement sensor using imaging array

A new subdivision method for grating-based displacement sensor was proposed in the present study, which takes advantages of imaging array's high resolution and pixels’ good uniformity in the space. In this method, the magnified grating image is received by imaging array and grating pitch is directly subdivided by pixels, which is quite different from that moiré fringe is subdivided by complex subsequent circuits in moiré-type displacement sensor. The displacement is statistically calculated by using the whole grating image, which greatly eliminates the errors arising from illumination, electrical signals’ fluctuation, grating defect, and so on. Therefore, the subdivision method is easy to obtain signal with high signal-to-noise ratio, insensitive to some external factors, and able to attain high measurement precision with low cost. In this paper, the principle of subdivision method was illuminated, the systemic resolution was theoretically discussed, the measurement precision was experimentally checked, and the uncertainty of measurement was analyzed. The subdivision system consisted of the grating with 20-μm pitch and the CMOS image sensor with the pixels of 1280×1024 had the resolution of 0.04 μm, and the maximum displacement error was less than 0.4 μm, which has been tested in the Abbe comparator platform.     

一种可提高压电复合材料d33和dh值的新型结构传感器

原理分析和实验结果证明了：通过一种含有空腔的金属电极与压电复合材料的界面作用，发迹了应力的作用式，提高了ｄ３３值；并使数值符号相反的ｄ３３和ｄ３１均对ｄｈ值起加大作用。     

A hypothetical new class of superhard materials

Summary By means of topological arguments we predict a new class of 4-coordinated covalent carbon lattices having a hollow structure (hollow diamonds (HDs)). A calculation of their structural and elastic properties based on the Tersoff potential indicates a stability and hardness very close to, albeit smaller than diamond. However, the intercalation of the smallest HDs with either mono- or divalent ions is estimated to give newnanocomposite materials which are harder than diamond. Work first reported at the LXXX National Conference of the Italian Physical Society, Lecce, Italy, Sept. 26–Oct. 1, 1994.     

A new class of optimum amplitude filters

This paper presents a new class of optimum amplitude filters for the maximization of the factor of encircled energy within a pre-specified central core area of the far-field diffraction pattern. The filters are composed of finite uniformly transmitting zones with variations between them. The analysis is based on the known technique of indirect search for the optimum filter by “the method of sets of screens” utilising the complete set of normal orthogonal Walsh functions as a system of base functions. Some numerical results are presented.     

A new class of plane symmetric solution

A new class of static plane symmetric solution of Einstein field equation generated by a perfect fluid source is put forward. A special family of this new solution is investigated in detail. The constraints on the parameters by different energy conditions are studied. The classical stability of this solution is discussed. The junction conditions matching to Minkowski metric and Taub metric are analyzed respectively.     

A new class of long-tailed pausing time densities for the CTRW

We present some asymptotic results for the family of pausing time densities having the asymptotic (t) property(t) [t ln¹⁺(t/T)]^–1. In particular, we show that for this class of pausing time densities the mean-squared displacement r ²(t) is asymptotically proportional to ln(t/T), and the asymptotic distribution of the displacement has a negative exponential form.     

A new laser displacement sensor based on triangulation for gauge real-time measurement

A new laser displacement sensor has been designed, constructed, and used in a train running at a speed of 64 km/h. The laser displacement sensor is insensitive to ambient light and to temperature. The parameters of the laser displacement sensor are as follows: the measurement range is 20 mm, and the laser displacement sensor resolution is 0.3 mm. All the results show that this new displacement sensor meets the requirement for real-time gauge measurement.     

MuMax: A new high-performance micromagnetic simulation tool

We present MuMax, a general-purpose micromagnetic simulation tool running on graphical processing units (GPUs). MuMax is designed for high-performance computations and specifically targets large simulations. In that case speedups of over a factor 100 × can be obtained compared to the CPU-based OOMMF program developed at NIST. MuMax aims to be general and broadly applicable. It solves the classical Landau-Lifshitz equation taking into account the magnetostatic, exchange and anisotropy interactions, thermal effects and spin-transfer torque. Periodic boundary conditions can optionally be imposed. A spatial discretization using finite differences in two or three dimensions can be employed. MuMax is publicly available as open-source software. It can thus be freely used and extended by community. Due to its high computational performance, MuMax should open up the possibility of running extensive simulations that would be nearly inaccessible with typical CPU-based simulators.     

A new class of anisotropic nonexchange spin waves

It is shown, using a thin magnetic film of a tetragonal antiferromagnet as an example, that indirect spin-spin exchange via the long-range field of quasi-static magnetoelastic deformations with allowance for the magnetocrystalline anisotropy results in qualitatively new types of nonexchange propagating spin waves, both surface and bulk. The case of an isolated magnetic film and a magnetic film with a one-sided or two-sided coating is studied.