Theoretical and Experimental Study of the Conformation and Vibrational Frequencies of N‐Acetyl‐L‐alanine and N‐Acetyl‐L‐alaninate

The vibrational frequencies of N‐acetyl‐L‐alanine (NAAL), its potassium salt (NAALK) and its free anionic form (NAAL^?) are calculated using density functional theory (B3LYP) combined with the 6‐311 + + G(d,p) basis set. The experimental Raman spectrum of solid NAALK and the scaling factors for calculated values are discussed as well. The three species are characterized by intramolecular NH…O hydrogen bonds leading to the formation of a five‐membered ring. As indicated by the intramolecular (N)H…O distances and by the ν(NH) frequencies, the strength of the intramolecular hydrogen bond is ordered as follows: NAAL^? < NAALK < NAAL^?. Owing to their difference in the coupling with other vibrational modes, the in‐plane and out‐of‐plane vibrations do not reflect the strength of the hydrogen bond.     

Experimental and Theoretical Study of Carnosine in THz Range

The characteristic fingerprints of carnosine from 0.2 to 2.6 THz are first measured by terahertz time-domain spectroscopy at room temperature. For the pure carnosine, the refractive index varies between 1.79 and 1.85 with the average value 1.84, while for the carnosine-polyethylene mixture, four absorption peaks centred at 1.37, 1.56, 1.85 and 2.49 THz are detected. A comparison of the theoretical predictions using the density functional theory with the experimental results shows satisfactory agreement except somewhat blue shift.     

Theoretical and Experimental Study of Time Reversal in Cubic Crystals

The self-adaptive focusing of the time reversal in anisotropic media is studied theoretically and experimentally. It is conducted for the compressional wave field in the cubic crystal silicon. The experimental result is in agreement with our theoretical analysis. The focusing gain and the displacement distributions of the time reversal field are analysed in detail. It is shown that the waves from different elements of the transducer array arrive at the original place of the source simultaneously after the time reversal operation. The waveform distortions caused by the velocity anisotropy can automatically be compensated for after the time reversal processing.     

Theoretical and Experimental Study of Singly－resonant Optical Parametric Oscillator

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Theoretical and Experimental Study of Scattering of a Plane Wave by an Inhomogeneous Plasma Sphere

Scattering of electromagnetic waves by an inhomogeneous plasma sphere has been studied theoretically and experimentally. The offset angles of electromagnetic waves caused by the plasma sphere have been observed experimentally. The effects of the electromagnetic wave frequency and plasma density on the offset angle are discussed. The plasma density is estimated with the offset angle.     

Theoretical results concerning the influence of non‐random‐field defects

We shall focus on extended defect systems and review their critical behavior. Primarily, with two aims, one of which is to understand phase transitions and how to derive effective dimension of extended defects with various structures, and the other is to propose a new research-method for defect systems, we let extended defects grow on a triangular lattice with frustration in a similar fashion to diffusion-limited aggregation, and discuss the situation. The existence of phase transitions, phase diagram, effective defect dimension, etc. will be shown. Furthermore, we shall summarize theoretical studies of extended defect systems on phase diagrams, critical behavior, tricritical behavior, and crossover behavior as static properties, and on nonconserved systems and conserved systems as dynamic properties.     

A Theoretical Study of Clusters： Realizing Differences between the Second-Row and the Third-Row Elements

Based on the characteristics of valence bonds and the first-principle molecular dynamics simulation we present an optimum valence bond scheme to study properties of important critical clusters with limited computational effort. The differences between the second-row and the third-row elements belonging to the same families can be understood by examining electronic structures and geometric structures even for small size clusters.     

Influence of Thermal Treatment on the Thermal Behavior of Poly‐L‐lactide

The influences of thermal treatment on cold crystallization and the thermal behavior of poly‐L‐lactide (PLLA) were investigated by DSC and polarizing microscopy. Both the cooling and heating rates had effects on cold crystallization. Double peaks were observed for the samples on subsequently heating at 10°C min^?1 after cooling between 5 and 20°C min^?1. The degrees of crystallinity dramatically increased with decreasing cooling rate, and the size of PLLA spherulites increased with a decrease in the cooling rate. Double cold crystallization peaks were also observed during heating traces at higher rates for this material after fast cooling (20°C min^?1) from the melt. The competition between the crystallization from the nuclei formed during cooling, and that from spontaneous nucleation might be responsible for the appearance of double peaks.     

Theoretical and Experimental Investigation of Ultrasonic Focusing with Annular Phased Array

The focused acoustic field generated by an annular array interface are investigated theoretically and experimentally. transducer and its reflection field on a solid-liquid Theoretically, the concise analytic expressions about the radiation and reflection acoustic fields of the annular phased array are obtained by the ray approach method （saddle-point method）. In experiment, an annular transducer with 8 equal-area elements is designed and fabricated, and a series of experiments about the radiation acoustic field and its reflection on the liquid-solid interface are carried out. The experimental characteristics of the transducer are in good agreement with the numerical ones. It shows the correctness of the theoretical result and the feasibility of dynamic focusing of the experiment system. With the maximum amplitude and its emergence time of the reflection wave, we can acquire the information and the imaging of the reflection interface by the annular phased array dynamic focusing.     

Experimental and Theoretical Evidence for the Existence of Broad Forbidden Gaps in the Three—Component Composite

The influence of localized resonance on the properties of band-gaps of the two-dimensional periodic composite are analysed numerically and experimentally by comparing the two-component phononic crystal with the three-component one. The three-component composite which exhibits localized resonance in the elastically soft coating ring is composed of a square array of coated cylinders embedded in an epoxy resin. The coated cylinders consist of a steel inner core and a rubber coating, which has much smaller wave velocity and mass density than the matrixand tile inner material. Tile measured transmission power of tile three-component composite drops to the noise level in a broad ultrasonic frequency interval in contrast to the binary composite, which is in good agreement with the calculation using the finite element method.     

Experimental Study of High Temperature Fracture Behavior of A286 Superalloy at 650°C

In this paper an experimental work is done for investigation of high temperature fracture properties of A286 superalloy at 650°C. Stress intensity factor K and parameter C* for this superalloy are determined experimentally. For estimation of these parameters, an instrument is developed for investigation of high temperature fracture properties. For estimation of stress intensity factor, compliance method is used. For this purpose four different compact tension specimens are tested and the parameter K is estimated. Creep tests are done for the selected specimens and parameter C* is determined by semiempirical relationships at 650°C. In these tests it is concluded that the specimens are placed near the plane stress condition. Crack growth behavior of this alloy is also studied. High incubation time (600 h) leads to overaging and therefore this alloy after this time showed very ductile creep properties, and fast creep crack growth was the major result of this overaging phenomenon. Finally the obtained results are compared with well-known nonexperimental methods for determination of these parameters. The obtained results showed that the results are in good agreement with each other.     

Theoretical Analysis and Experimental Study on Generation of a Dark Hollow Beam by a Micron-sized Hollow Optical Fiber

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Electrochemical Synthesis and Structure of Poly(2‐methyl‐1‐naphthylamine) Films

A novel polymer, poly(2‐methyl‐1‐naphthylamine), which was synthesized electrochemically at various temperatures from a solution containing 2‐methyl‐1‐naphthylamine, acetic acid and sodium acetate, was characterized by IR spectroscopy. The structural conclusions were based on comparisons of polymer spectra with the IR‐spectrum of the monomer, 2‐methyl‐1‐naphthylamine. IR spectroscopy indicates that the electropolymerization proceeds via the –NH₂ groups and that the poly(2‐methyl‐1‐naphthylamine) structure consists of imine (–N?C) and amine (–NH–C) links between naphthalene rings as well as a free methyl groups in the chains. An analysis of the “substitution pattern” region in the polymer's spectra suggests that the polymer molecules were formed via mixed N–C(4), N–C(5) and N–C(7) linkages between repeated units. The ratio of between the 1645 and 1620 cm^? 1 peak areas decreases with increased temperature during synthesis, indicating that 25°C is the best temperature to obtain higher molecular weights.     

Power Analysis and Experimental Study of the Fiber Null Coupler with an Acousto-optic Device

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｈｉｇｈ ｐｅｒｆｏｒｍａｎｃｅ ｏｐｔｉｃａｌｓｗｉｔｃｈｉｎｇｔｅｃｈｎｏｌｏｇｉｅｓａｒｅｃｕｒｒｅｎｔｌｙｏｆｅｎｏｒｍｏｕｓｉｎｔｅｒｅｓｔｆｏｒｔｈｅｃｏｍｍｕｎｉｃａｔｉｏｎｓｉｎｄｕｓｔｒｙ .Ｔｏｄａｔｅｍａｎｙｔｅｃｈｎｏｌｏｇｉｅｓｈａｖｅ ｐｒｏｄｕｃｅｄｈｉｇｈ ｐｅｒｆｏｒｍａｎｃｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓ[1,2 ] .Ｔｈｅｒｅｑｕｉｒｅｍｅｎｔｆｏｒｔｈｅｓｕｃｃｅｓｓｆｕｌｔｅｃｈｎｏｌｏｇｉｅｓｗｉｌｌｂｅｌｏｗｉｎｓｅｒｔｉｏｎｌｏ…     

Approximate Theoretical Study on the Characteristic of a Femtosecond KLM Laser

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｗｉｔｈｉｎｃｅｓｓａｎｔａｐｐｅａｒａｎｃｅｏｆｎｅｗｌａｓｅｒｃｒｙｓｔａｌｓｗｉｔｈｅｖｅｒｗｉｄｅｒｆｌｕｏｒｅｓｃｅｎｃｅｓｐｅｃｔｒｕｍ,ｓｕｃｈａｓＴｉ∶ｓａｐｐｈｉｒｅ,Ｃｒ4 ∶ＹＡＧ,ｔｈｅｐｒｅｌｉｍｉ...     

Theoretical Study of the Opacity for Mixture Materials at High Temperatures

Using a detailed configuration accounting model with term structures treated by the umresolved transition array model,we have extensively investigated the opacitiesof mixture materials.For plasmas at the temperature of 250 eV and density of 1 g/cm^3,our calculated Rosseland mean opacities are in good agreement with other theoretical results.A high increase in the Rosseland mean opacity to 2944cm^2/g is achieved for a multi-element mixture compared to the value of 1729cm^2/g for pure gold.Various mixtures at other plasma conditions are also studied.     

Thermal Behavior of Polyamide‐12 and Poly (Styrene‐Co‐Acrylonitrile) Blend

In this work, an unusual morphology of a mixture of polyamide‐12 (PA‐12) with a series of poly (styrene‐co‐acrylonitrile) (SAN) was obtained by solution casting and fast solvent evaporation. The prepared film was transparent although it contained many crystals. These crystals apparently prevented phase separation despite the instability of the PA‐12 and SAN mixtures below 180°C. In isothermal experiments, once the crystals were melted, phase separation began and the scattered intensity fit the Cahn–Hilliard theory. When the AN content in the SAN copolymer was less than 5%, the phase separation took place when only part of the crystals were melted at 180°C. However, due to the constraint of unmelted crystals, the growth rate of phase separation at this temperature was much slower.     

Synthesis and Thermal Behavior of Silica‐Graft‐Polypropylene Nanocomposites Studied by Step‐Scan DSC and TGA

Silica graft poly(propylene) (silica‐g‐PP) nanocomposites were successfully prepared by radical grafting copolymerization and ring‐opening reaction. Their thermal properties were studied by step‐scan differential scanning calorimetry (SDSC) and thermogravimetric analysis (TGA). The exothermic peaks in the IsoK baseline (C_p,IsoK, nonreversing signal) of SDSC reveal that PP and silica‐g‐PP nanocomposites undergo melting‐recrystallization‐remelting during heating. The peak temperatures of recrystallization and remelting shift upward with the existence of nanoparticles in the PP matrix. The thermal degradation kinetics of silica‐g‐PP nanocomposites were investigated using nonisothermal TGA and the Flynn‐Wall‐Ozawa method. The results indicate that the thermal stability was significantly improved with increasing silica content, mainly because of the physical‐chemical adsorption of the volatile degradation products on the nanoparticles that delays their volatilization during decomposition, and the covalent interaction between nanoparticles and PP chains, which will also reduce the breakage of PP backbone chains.     

Experimental Study of the Intensity Spatial Distribution Uniformity of the Output Field from Multimode Fibers

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Experimental and Theoretical Analysis of Gradient—Index Lens Diffraction by Matrix Optics

We Present the diffraction patterns observed in the gradient-index(GRIN) lens sensor experiment.Then the diffraction pattern of radial GRIN lens is explored by using matrix optics,The theoretical results agree with the experimental results of 27.9-long GRIN lens with 2-mm diameter diffraction patterns.