Correspondence between the electronic structure and phase separation in a K-doped FeSe system.

Phase separated potassium intercalated FeSe thin films have been synthesized by pulsed laser deposition. The coexistence of FeSe phase and 245 phase was investigated both by x-ray photoemission spectroscopy (XPS) and x-ray diffraction. The volume ratio of these two phases is sensitive to temperatures and amount of extra potassium dosing. The XPS and ultraviolet photoelectron spectroscopy results indicated that these two phases shows the different hybridization strength between adjacent Fe layer and Se layer. We infer that the layered electronic structure is the necessary condition of superconductivity in potassium-doped FeSe system, and the phase separation is driven by competition between quasi-2D and 3D bonding mode within FeSe layer. Similar competition may also be able to interpret the phase seperation in K x Fe2-y Se2 bulk single crystal.

Prognostic factor from MR spectroscopy in rat with astrocytic tumour during radiation therapy.

OBJECTIVE: To investigate the relationship between the tumour volume and metabolic rates of astrocytic tumours using MR spectroscopy (MRS) during radiation therapy (RT). METHODS: 12 healthy male Sprague-Dawley® rats (Sprague-Dawley Animal Company, Madison, WI) were used, and a tumour model was created through injecting C6 tumour cells into the right caudate nuclei of the rats. Tumours grew for 18 days after the injection and before the imaging study and radiation treatment. MRS was performed with two-dimensional multivoxel point-resolved spectroscopy sequence using a GE Signa VH/i 3.0-T MR scanner (GE Healthcare, Milwaukee, WI) equipped with rat-special coil. RT was given on the 19th day with a dose of 4 Gy in one single fraction. The image examinations were performed before RT, and on the 4th, 10th, 14th and 20th days after treatment, respectively. GE FuncTool software package (GE Healthcare) was used for post-processing of spectrum. RESULTS: Metabolic ratios of serial MRS decrease progressively with time after RT. Choline-containing components (Cho)/creatine and creatine phosphate (Cr) ratios immediately prior to RT differed significantly from those on the 10th, 14th and 20th days after RT; both Cho/N-acetyl aspartate (NAA) ratios and NAA/Cr ratios immediately prior to RT differed significantly from those on the 14th and 20th days after RT. A positive correlation between changes of tumour volume and changes of Cho/Cr, lipid and lactate/Cr and glutamate plus glutamine/Cr ratio was observed on the 4th day after RT. CONCLUSION: MRS provides potential in monitoring tumour response during RT, and the imaging biomarkers predict the response of astrocytic tumours to treatment. ADVANCES IN KNOWLEDGE: MRS is combined with both tumour size and Ki-67 labelling index to access tumour response to radiation.

Generating ultrabroadband terahertz radiation based on the under-compression mode of velocity bunching.

We propose and analyze a scheme to generate enhanced ultrabroadband terahertz (THz) radiation through coherent transition radiation emitted by ultrashort electron beams based on a 10.5 m beamline at Tsinghua University. The proposed scheme involves the initial compression of the electron beam with a few hundred pC charges using a velocity bunching scheme (i.e., RF compression) in an under-compression mode instead of the usual critical-compression mode in order to maintain a positive energy chirp at the exit of the traveling wave accelerator. After a long drift segment, the particles in the tail catch up with the bunch head. More than 80% of the particles are distributed in a spike with an rms length less than 20 fs. Such beams correspond to an ultrabroadband coherent transition radiation (CTR) spectrum of 0.1 THz to 25 THz, with the single-pulse THz radiation energy of up to 50 µJ. The principle of CTR and under-compression mode of velocity bunching are introduced in this paper. And the ASTRA simulation parameters and the stability of the system are also discussed.

Cold ischemia time influences spermatogenesis in a testicular ischemia/reperfusion injury model.

OBJECTIVE: To evaluate the influence of cold ischemia time on spermatogenesis in a rabbit model of testicular ischemia-reperfusion (I/R) injury. MATERIAL AND METHODS: The testicular I/R model was established in 24 male white rabbits. The left testes were preserved using HC-A solution at 0 degrees C to 4 degrees C. Cold ischemia time was 1, 2, 4, and 6 hours. The right testes without vascular occlusion were used as autologous controls. Twenty-four hours after reperfusion, the animals were sacrificed, and samples were obtained at bilateral orchiectomy. Another 8 normal testes were used as normal controls. Testicular tissue Johnsen score, malondialdehyde concentration, and apoptosis index were used to evaluate spermatogenesis. RESULTS: The Johnsen score decreased and the apoptosis index increased with the duration of cold ischemia time in the I/R groups. The malondialdehyde concentration in the I/R groups was significantly higher than the sham and normal groups, and was highest at 4 hours of cold ischemia time. CONCLUSION: Testicular I/R injury is highly related to cold ischemia time. In rabbit models, testis transplantation is best performed within 4 hours of cold ischemia with traditional hypothermic protection.

Body-centered-cubic Ni and its magnetic properties.

The body-centered-cubic (bcc) phase of Ni, which does not exist in nature, has been achieved as a thin film on GaAs(001) at 170 K via molecular beam epitaxy. The bcc Ni is ferromagnetic with a Curie temperature of 456 K and possesses a magnetic moment of 0.52+/-0.08 micro(B)/atom. The cubic magnetocrystalline anisotropy of bcc Ni is determined to be +4.0x10(5) ergs x cm(-3), as opposed to -5.7x10(4) ergs x cm(-3) for the naturally occurring face-centered-cubic (fcc) Ni. This sharp contrast in the magnetic anisotropy is attributed to the different electronic band structures between bcc Ni and fcc Ni, which are determined using angle-resolved photoemission with synchrotron radiation.

[A study on the inheritance of dried tofu output of soybean].

The P1, P2, F1, F2 and F2:3 in plant generation of three crosses of Liuhexiaoyeqing x Xinyixiaohedou, Shangraoganbusi x Huaiyinqiuhedou and Liuhexiaoyeqing x Nannong 73-935 were used to study the inheritance of dried tofu output. The results of the joint analyses of multiple plant generations showed a consistant one major gene plus polygene mixed inheritance model. The heritability values for dried tofu output were as high as 87.84%-99.98%. In plant generation F2:3 of these crosses, the heritabilities of major gene were 51.80%-61.85%, and those of polygene were 36.12%-48.03%. Therefore, both major gene and polygene effects were important and should be utilized in breeding program.

[Tumor necrosis factor and interleukin 6 in acute leukemia].

In order to clarify the role of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF alpha) in the pathogenesis of acute leukemia, IL-6 and TNF alpha level was determined in patients with various types of acute leukemia. In comparison with normal subjects, IL-6 activity was significantly elevated in patients with ALL and ANLL (P < 0.01) and TNF alpha level increased in patients with ANLL (P < 0.05). The effect of IL-6 and TNF alpha on leukemia cell in vitro was also observed. The results indicated that IL-6 can promote the proliferation of leukemia cells, while TNF alpha can inhibit proliferation of leukemia cell in vitro. It is suggested that abnormal level of TNF alpha and IL-6 in patients with acute leukemia is probably related to the pathogenesis of acute leukemia.