Effect of low level laser irradiation on the proliferation of myoblasts—the skeletal muscle precursor cells: an experimental in vitro study

The aim of this paper is to study the effect of low-level laser irradiation (LLLI) on proliferation of myoblasts in culture. Myoblasts derived from rat skeletal muscle were irradiated by He-Ne laser with different doses. Compared with nonirradiated control group, the number of myoblasts increased when the cells in normal culture conditions were exposed to the laser of specific energy density. The amount of cells with proliferating cell nuclear antigen (PCNA) positive expression and the 5-bromo-2′-deoxyuridine (BrdU) incorporation rate after laser irradiation were also higher than that of the control group, suggesting that LLLL at certain doses can effectively enhance myoblasts growth activity in vitro. This study firstly demonstrated that stimulating myoblasts to enter into proliferative stage from initial resting state was an important mechanism of regeneration and repair of injured skeletal muscle promoted by LLLI in clinical treatment.     

High slope efficiency and low threshold in a laser-diode-pumped passively Q-switched ion-implanted Nd:YVO<Subscript>4</Subscript> planar waveguide laser with GaAs saturable absorber

A passively Q-switched waveguide laser, to our knowledge, has been firstly demonstrated in Nd: YVO₄ crystal formed by 3 MeV Si⁺ ion implantation at a dose of 1 × 10¹⁵ ions/cm² at room temperature, in which GaAs was used as saturable absorber. The dependences of the average output power, pulse width, pulse repetition rate on absorbed pump power have been measured at different output plane mirror transmissions. At an absorbed pump power of 78.8 mW and output transmission of 20%, the shortest pulse width of 3.88 ns was obtained, corresponding to the peak power and single pulse energy of 212 W and 0.82 μJ, respectively. The threshold pump power was as low as 40 mW, and the slope efficiency was about 64.5% when the absorbed pump power was lower than 70 mW.     

The magnetic properties of nanosized La<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Ca<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>MnO<Subscript>3</Subscript> (0.5 ≤ <Emphasis Type="Italic">x</Emphasis> ≤ 0.8)

Magnetic properties of La_1−x Ca _x MnO₃ (0.5 ≤ x ≤ 0.8) samples with an equivalent average particle size ~50 nm prepared by a sol–gel method were investigated. The charge ordering (CO) transition that is observed in the bulks disappears and the ferromagnetic (FM) transition occurs in all the prepared samples. For all the samples, the spontaneous magnetization (M _S) value is much lower than the corresponding theoretic value, which shows that the majority of the sample is antiferromagnetic (AFM). However, the M _S value is much larger than the corresponding value reported by some other groups. The invisible of CO transition and the large M _S value can be attributed to the good connection among the adjacent particles. Moreover, the exchange bias (EB) phenomenon is observed except the x = 0.5 sample. With x increasing, the M _S value decreases and the EB field increases, which can be understood by considering the coexistence of FM phase with Mn³⁺–Mn⁴⁺ spin clusters in the shell and the AFM phase in the core of the nanoparticles.     

Electronic structures of alloy quantum dots with nonuniform composition

In this study, the significant effect of the nonuniform composition in alloy quantum dots (QDs) on electronic structure is analyzed in depth. The equilibrium composition profiles in experimentally observed dome and barn shaped GeSi/Si QDs are determined by combining the finite element method and the method of moving asymptotes. Due to the composition variation, the total band edge of heavy hole is dominated by the band offset and spin-orbit coupling rather than the strain effect. The numerical results reveal that the wave function of heavy hole trends to be localized in the Ge-rich region at the top of the large QD. Moreover, the size effect gradually compensates the composition effect as the size of QD decreases.     

Magnetocaloric effect in La(Fe<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>)<Subscript>13</Subscript> ferromagnets

The isothermal changes in the magnetic entropy and the lattice entropy and the adiabatic temperature change in La(Fe_0.88Si_0.12)₁₃ and La(Fe_0.86Si_0.14)₁₃ ferromagnets in a magnetic field are calculated. The calculations are performed with a generalized magnetostriction model of a ferromagnet; the calculation results are compared to experimental data. It is shown that the change in the lattice entropy decreases the magnetocaloric effect and makes it possible to explain the experimental data obtained for La(Fe _x Si_{1 − x} )₁₃ (x = 0.86, 0.88) ferromagnets. The temperature dependences of the bulk compression moduli of these ferromagnets are calculated, and these dependences indicate a strong lattice softening in the vicinity of the magnetic phase transition in them. The thermal expansion coefficient and some magnetic properties of the ferromagnet with x = 0.86 are measured to determine the numerical values of the parameters entering into calculation formulas.     

Electronic structure of p-type La1 ? xM x2+ MnO3 manganites in the ferromagnetic and paramagnetic phases in the LDA + GTB approach

The band structure, spectral intensity, and position of the Fermi level in doped p-type La_{1 − x} M _x/2+MnO₃ manganites (M = Sr, Ca, Ba) is analyzed using the LDA + GBT method for calculating the electronic structure of systems with strong electron correlations, taking into account antiferro-orbital ordering and using the Kugel-Khomskii ideas and real spin S = 2. The results of the ferromagnetic phase reproduce the state of a spin half-metal with 100% spin polarization at T = 0, when the spectrum is of the metal type for a quasiparticle with one spin projection and of the dielectric type for the other. It is found that the valence band becomes approximately three times narrower upon a transition to the paramagnetic phase. For the paramagnetic phase, metal properties are observed because the Fermi level is located in the valence band for any nonzero x. The dielectrization effect at the Curie temperature is possible and must be accompanied by filling of d _x orbitals upon doping. The effect itself is associated with strong electron correlations, and a complex structure of the top of the valence band is due to the Jahn-Teller effect in cubic materials.     

Efficient intracavity second-harmonic generation at 1063 nm in a GdCOB crystal

We report an efficient intracavity second-harmonic generation (SHG) at 1063 nm in a non-linear optical crystal, GdCa₄O(BO₃)₃ (GdCOB), performed with a diode end pumped continuous-wave (CW) Nd:GdVO₄ laser. In the case of a laser with an a-cut 0.4 at % Nd:GdVO₄ crystal frequency-doubled with a GdCOB crystal cut for Type I frequency doubling. A CW SHG output power of 2.25 W has been obtained using a 15 mm long GCOB crystal. The optical conversion efficiency with respect to the incident pump power was 12.4%.     

Laser based fabrication of chitosan mediated silver nanoparticles

We report fabrication of silver nanoparticles (Ag NPs) by laser ablation technique in different concentrations of aqueous chitosan solution. The ablation process of silver plate was carried out by using a nanosecond Q-switched Nd:YAG pulsed laser and the characterization of Ag NPs was done by Transmission electron microscopy, UV-Vis spectroscopy, and X-ray diffraction. UV-visible plasmon absorption spectra revealed that the formation efficiency as well as the stability of nanoparticles was increased by addition of chitosan. On the other hand, the size decrement of nanoparticles was more remarkable in the higher chitosan concentration.     

Optical properties of PMN–PT thin films prepared using pulsed laser deposition

(1 ? x)Pb(Mg_1/3Nb_2/3)O₃–xPbTiO₃ (PMN–PT) thin films have been deposited on quartz substrates using pulsed laser deposition (PLD). Crystalline microstructure of the deposited PMN–PT thin films has been investigated with X-ray diffraction (XRD). Optical transmission spectroscopy and Raman spectroscopy are used to characterize optical properties of the deposited PMN–PT thin films. The results show that the PMN–PT thin films of perovskite structure have been formed, and the crystalline and optical properties of the PMN–PT thin films can be improved as increasing the annealing temperature to 750 °C, but further increasing the annealing temperature to 950 °C may lead to a degradation of the crystallinity and the optical properties of the PMN–PT thin films. In addition, a weak second harmonic intensity (SHG) has been observed for the PMN–PT thin film formed at the optimum annealing temperature of 750 °C according to Maker fringe method. All these suggest that the annealing temperature has significant effect on the structural and optical properties of the PMN–PT thin films.     

Preparation of chemically deposited thin films of CdS/PbS solar cell

The present paper reports the preparation of a solar cell which has a cross-sectional scheme: ITO/CdS/PbS, containing a commercially transparent conductive ITO; chemically deposited n-type CdS (340 nm) and absorbed layer of p-type PbS (1400 nm). The structural and optical properties of the constituent films are presented. X-ray diffraction showed that all of the thin films are polycrystalline. Using scanning electron microscopy, the present study revealed that the films have uniform surface morphology over the substrate. The solar cell was characterized by determining the open circuit voltage, short-circuit current density, and J–V under 40 mW/cm² solar radiation. The efficiency of the solar cells was 1.35%, which is much higher (0.041, 0.5 and 0.1–0.4%) and slightly smaller (1.65%) than some solar cells reported in the literature.