Alleviation of pre-exposure of mouse brain with low-dose C-12(6+) ion or Co-60 gamma-ray on male reproductive endocrine damages induced by subsequent high-dose irradiation

Irradiation has been widely reported to damage organisms by attacking on proteins, nucleic acid and lipids in cells. However, radiation hormesis after low-dose irradiation has become the focus of research in radiobiology in recent years. To investigate the effects of pre-exposure of mouse brain with low-dose C-12(6+) ion or Co-60 gamma (gamma)-ray on male reproductive endocrine capacity induced by subsequent high-dose irradiation, the brains of the B6C3F(1) hybrid strain male mice were irradiated with 0.05 Gy of C-12(6+) ion or Co-60 gamma-ray as the pre-exposure dose, and were then irradiated with 2 Gy as challenging irradiation dose at 4 h after pre-exposure. Serum pituitary gonadotropin hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), testosterone, testis weight, sperm count and shape were measured on the 35th day after irradiation. The results showed that there was a significant reduction in the levels of serum FSH, LH, testosterone, testis weight and sperm count, and a significant increase in sperm abnormalities by irradiation of the mouse brain with 2 Gy of C-12(6+) ion or Co-60 gamma-ray. Moreover, the effects were more obvious in the group irradiated by C-12(6+) ion than in that irradiated by Co-60 gamma-ray. Pre-exposure with low-dose C-12(6+) ion or Co-60 gamma-ray significantly alleviated the harmful effects induced by a subsequent high-dose irradiation.

Adaptive hormetic response of pre-exposure of mouse brain with low-dose C-12(6+) ion or Co-60 gamma-ray on growth hormone (GH) and body weight induced by subsequent high-dose irradiation

The brain of the Kun-Ming strain mice were irradiated with 0.05 Gy of C-12(6+) ion or Co-60 gamma-ray as the pre-exposure dose, and were then irradiated with 2 Gy of 12C6+ ion or Co-60 gamma-ray as challenging irradiation dose at 4 h after per-exposure. Body weight and serum growth hormone (GH) concentration were measured at 35th day after irradiation. The results showed that irradiation of mouse brain with 2 Gy of C-12(6+) ion or Co-60 gamma-ray significantly diminished mouse body weight and level of serum GH. The relative biological effectiveness values of a 2 Gy dose of C-12(6+) ion calculated with respect to Co-60 gamma-ray were 1.47 and 1.34 for body weight and serum GH concentration, respectively. Pre-exposure with a low-dose (0.05 Gy) of C-12(6+) ion or Co-60 gamma-ray significantly alleviated reductions of mouse body weight and level of serum GH induced by a subsequent high-dose (2 Gy) irradiation. The data suggested that low-dose ionizing irradiation can induce adaptive hormetic responses to the harmful effects of pituitary by subsequent high-dose exposure.

Study on variable capacitance diode of (p)nc-Si : H/(n)c-Si heterojunction

Hydrogenated nanocrystalline silicon (nc-Si:H) layers of boron-doped increasing step by step was deposited on n-type crystalline silicon substrate using Plasma Enhanced Chemical Vapor Deposition (PECVD) system. After evaporating Ohm contact electrode on the side of substrate and on the side of nc-Si:H film, a structure of electrode/ (p)nc-Si:H/(n)c-Si/electrode was obtained. It is confirmed by electrical measurement such as I-V curve, C-V curve and DLTS that this is a variable capacitance diode. (C) 2003 Elsevier Science Ltd. All rights reserved.

Nonlinear optical properties and thermal stability of the poled polymer NTAB/PEK-c

Films of high glass' transition temperature polymer polyetherketone doped with chromophore 2,2'[4-[(5-nitro-2-thiazolyl)azophenyl]-amino]-bisethanol NTAB) were prepared, poled by the corona-onset poling setup which includes a grid voltage making the surface-charge distribution uniform at elevated temperature. The thickness of the films was measured by the Model 2010 Prism Coupler system. Second harmonic generation d(33) was measured by the second harmonic generation method, and the d33 is 38.12 pm/V at 1064 nm under the absorption correction. The nonlinear optical activity maintains is 80% of its initial value. (C) 2002 Elsevier Science B.V. All rights reserved.

Electro-optical properties and temporal stability of the guest-host DCNP/PEK-c polymer thin film

The polyetherketone (PEK-c) guest-host system thin films in which the range of the weight percent of 3-(1,1-dicyanothenyl)-1-phenyl-4, 5- dihydro-1H-pryazole (DCNP) is from 20% to 50% were prepared. The predicted high value of electro-optical (EO) coefficient gamma(33) = 48.8 pm/V by using two-level model was obtained when the weight percent of DCNP in the polymer system is 40%, whereas EO coefficients are attenuated at higher chromophore loading then 40%. The temporal stability of the EO activity of the guest-host polymer was evaluated by probing the decay of the orientational order of the chromophores in the polymer system.