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We theoretically investigate the dwell time for electrons in an antiparallel double $\delta $ -magnetic-barrier nanostructure, which is constructed on the surface of the InAs/Al x In1- x As heterostructure by patterning two ferromagnetic (FM) stripes. It is shown that the dwell time is dependent on electron spins due to the spin–field interaction between spins and magnetic fields. It is also shown that both magnitude and sign of the spin polarization in the dwell time can be modulated by the structural width or magnetic-strength difference between two magnetic barriers, which may give rise to a controllable temporal spin splitter for spintronics device applications.

The dwell time of electrons in a parallel double δ-magnetic-barrier (MB) nanostructure constructed by patterning an asymmetric ferromagnetic stripe on both the top and bottom of an InAs/AlxIn1−xAs heterostructure is calculated. Because the electron spins interact with the structural magnetic fields, the dwell time depends on the electron spins. Moreover, both the magnitude and sign of the spin-polarized dwell time can be modified by changing the magnetic field, the applied voltage, and the separation between the two δ-MBs. The electron spins can thus be separated in the time dimension, and such a magnetic nanostructure could serve as a controllable temporal spin splitter for use in spintronics device applications.

We report a theoretical investigation on wave-vector filtering (WVF) effect in a magnetic nanostructure, which can be experimentally realized by depositing ferromagnetic (FM) stripes on the surface of GaAs/AlxGa1-xAs heterostructure. An appreciable WVF effect appears in this nanosystem. The WVF efficiency is associated with structural parameters of magnetic nanostructure. Therefore, such a device can be employed as a momentum filter for nanoelectronics device applications.

Based on a magnetically confined GaAs/Al x Ga1– x As microstructure modulated by spin-orbit coupling (SOC), we propose a controllable electron-spin filter for spintronics applications. This device operates due to both Zeeman interaction and Rashba or Dresselhaus SOC. Its spin polarization can be tuned by changing interfacial confining electric field or engineering strain.

We report a theoretical investigation on Goose-Hänchen (GH) effect for spin electrons across a magnetically confined GaAs/AlxGa1-xAs microstructure modulated by spin-orbit coupling [(SOC), including Rashba and Dresselhaus types]. An intrinsic symmetry in the device is broken by SOC, which gives rise to a considerable spin polarization effect in GH shifts of electrons. Both magnitude and direction of spin polarization can be manipulated by Rashba or Dresselhaus SOC, i.e., interfacial confining electric field or strain engineering. Based on such a semiconductor microstructure, a controllable spatial spin splitter can be proposed for spintronics applications.

This study aimed to investigate the effects of SPAR signaling pathway on the restoration of motor function in ischemic stroke (IS). Sprague-Dawley male rats were separated into the control and sham groups, as well as the group for middle cerebral artery occlusion (MCAO) model establishment. Successfully established rat ischemic models were randomly divided into model, SNKMCAO-del and pcDNA3.1-SNK groups. The evaluation of motor function among the rats in each group was assessed using a balance beam, a screen test and the Garcia scoring method. CatWalk gait analysis was employed to evaluate the effect of the SNK signaling pathway on rat motor function. Triphenyltetrazolium chloride (TTC) and TUNEL staining were techniques were utilized for cerebral infarction (CI) area as well for hippocampal neuron apoptosis. The quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting methods were performed to detect mRNA and protein expressions of SNK and SPAR. When compared with the model group, the SNKMCAO-del group displayed decreased motor function score and CI area, while contrasting results were observed in the pcDNA3.1-SNK group. According to the results obtained from the CatWalk gait analysis, the SNKMCAO-del group showed a clear improvement compared to the model group whereas the pcDNA3.1-SNK group exhibited poorer results than the model group in the objective parameters of the study, such as movement, speed, running duration, print area, maximal contact area, maximal, mean intensity, and stride length. These findings suggested that SNK gene silencing promotes motor function by inhibiting the SNK-SPAR signaling pathway in rats with ischemic stroke.

The magnetically confined semiconductor heterostructure (MCSH) is often used as the momentum filter due to an essentially 2-D process for the electronic tunneling. Taking a typical MCSH into account, we theoretically investigate how to manipulate such momentum filters by the $\delta $ -doping technique. The momentum-filtering efficiency can be tuned because of the $\delta $ -doping dependence of the electron transmission. The involved MCSH can be employed as a controllable momentum filter.

We report on a theoretical study of giant magnetoresistance (GMR) effect in a δ -doped GaAs / Al x Ga 1 − x As heterostructure modulated by two stripes of ferromagnetic metal and a stripe of Schottky metal in parallel configuration. The δ -doping dependent transmission and conductance of the device are calculated. It is shown that a considerable giant magnetoresistance (GMR) effect exists in this structure. It is also shown that the magnetoresistance ratio ( MR ) can be switched by the δ -doping. The underlying physical mechanism of the results is analysed in light of δ -doping-dependent tunneling process in the device.

We report a theoretical study of spin-dependent transport in a magnetic nanostructure, which can be experimentally realized by depositing a ferromagnetic metal (FM) stripe and a Schottky metal (SM) stripe on the top and at the bottom of the semiconductor heterostructure. Theoretical analysis reveals that the intrinsic symmetry in a single FM-stripe magnetic system can be broken by the SM stripe placed at the bottom of the heterostructure, and thus a sizeable spin polarization effect appears. Numerical calculation shows that not only amplitude of the spin polarization but also its sign varies with the width and/or the position of the SM stripe.

We theoretically investigate Goos-Hänchen (GH) displacement by modelling the spin transport in an archetypal device structure-a magnetically confined GaAs/Al

OBJECTIVE: To explore the effect of recombinant human erythropoietin (rhEPO) on expression of brain-derived neurotrophic factor (BDNF) in different brain regions of aging rats. METHODS: Forty male SD rats were randomized equally into negative control group, D-galactose group, EPO treatment group, and positive control group. Rat models of subacute aging were established by continuous subcutaneous injection of 5% D-galactose. Immunohistochemical staining was used to analyze the variation of BDNF expressions in different brain regions of the aging rats with different treatments. RESULTS: Significant brain region-specific differences in BDNF expression were found among the rats in different groups. Compared with those in the negative control group, the numbers of BDNF-positive cells in the hippocampal CA1 region, CA3 region, dentate gyrus (DG) and frontal cortex were all decreased obviously in D-galactose group (P < 0.05) but increased in both EPO group and the positive control group (P < 0.05) without significant differences between the latter two groups. In the rats in the same group, the number of BDNF-positive cells varied markedly in different brain regions (P < 0.05), and the expression level of BDNF was the highest in the frontal cortex followed by the hippocampal CA3 region and the dentate gyrus, and was the lowest in the hippocampal CA1 region. CONCLUSION: Treatment with rhEPO enhances the expression of BDNF in rat neural cells, suggesting that rhEPO may protect the nervous system from aging by regulating the BDNF pathway.

We theoretically explore the control of the wave-vector filtering (WVF) effect in a hybrid magnetic-electric-barrier nanostructure, which can be experimentally realized by depositing a ferromagnetic (FM) stripe and a Schottky-metal (SM) stripe on top and bottom of a GaAs/Al $$_{\text {x}}$$ Ga $$_{1-x}$$ As heterostructure, respectively. It is shown that an obvious WVF effect appears in such a device. It is also shown that the degree of the WVF effect is related to the width and position of the SM stripe. In particular, the WVF effect can be tuned by the applied voltage to the SM stripe, and thus a manipulable momentum filter can be obtained for nanoelectronics applications.

We report a theoretical study on spin-polarized lateral displacement for the electron across a magnetic nanostructure with a zero average magnetic field, which can be experimentally realized by depositing a ferromagnetic stripe with a plumb magnetization on the top of a semiconductor heterostructure. It is shown that, the lateral displacement depends strongly on the electron spins due to the Zeeman coupling and the intrinsic symmetry, though the average magnetic field is vanishing in the nanostructure. It is also shown that the spin-polarized lateral displacement is related closely to the structural parameters. Therefore, such a novel magnetic nanostructure may be used as a spin spatial splitter for spintronics applications.

We study how the transmission properties of a two-dimensional electron gas, modulated by a ferromagnetic stripe and a Schottky metal (SM) stripe in a parallel configuration, can be modified by manipulating the voltage applied to the SM stripe. Both the transmission coefficient and conductance of the device are found to be strongly dependent on the electric-barrier height induced by an applied voltage under the SM stripe. Thus, transmission properties of electrons in the device can be conveniently tailored by means of tuning this applied voltage.

We investigate the Goos–Hanchen (GH) effect of spin electron beams in a magnetic-barrier (MB) nanostructure consisting of antiparallel double δ - MBs , which can be experimentally realized by depositing two ferromagnetic (FM) stripes on top and bottom of the semiconductor heterostructure. GH shifts for spin electron beams across this type of MB nanostructures, is derived exactly, with the help of the stationary phase method. It is shown that GH shifts depend strongly on the spin directions for double δ - MBs with unidentical magnetic strengths, giving rise to a considerable spin polarization effect. It also is shown that spin polarization of GH shifts is closely relative to the separation and magnetic-strength difference of two δ - MBs . These interesting properties may provide an alternative scheme to spin-polarize electrons into the semiconductor, and the devices can serve as tunable spin beam splitters.

In this study, we demonstrate that tumor-derived exosome-loaded dendritic cells can elicit a specific CD8(+) cytotoxic T-lymphocyte (CTL) response against autologous tumor cells in patients with malignant glioma. Exosomes were purified by ultrafiltration centrifugation and sucrose gradient ultracentrifugation. Exosomes had antigen-presenting molecules (MHC-I, HSP70), tumor antigen (MAGE-1) and adherent molecule (ICAM-1). After incubation with exosomes, the dendritic cells (DCs) could activate the T lymphocytes to become glioma-specialized CTL. The CTL had vigorous cytotoxicity to glioma cells as opposed to autologous lymphoblast cells. These data demonstrate that tumor exosome-loaded DC can be an effective tool in inducing glioma-specific CD8(+) CTLs able to kill autologous glioma cells in vitro. In conclusion, exosomes are a natural and new source of tumor-rejection antigens, opening up new avenues for immunization against glioma.

Recently, an electron-spin filter was proposed by depositing a nanosized ferromagnetic metal stripe and a Schottky normal metal stripe on the top of the semiconductor heterostructure [F. Zhai, H. Q. Xu and Y. Guo, Phys. Rev. B70 (2004) 085308]. This device has a considerable electron-spin polarization and potential application in spintronics. Here we apply a bias to this device and theoretically demonstrate how to manipulate its electron-spin polarization. By numerical simulations, we found that not only the amplitude of the electron-spin polarization but also its sign varies with the bias, giving rise to a bias-tunable spin filter device.

We theoretically investigate Goos-Hanchen (GH) displacement by modelling the spin transport in an archetypal device structure-a magnetically confined GaAs/Al x Ga1-x As nanostructure modulated by spin-orbit coupling (SOC). Both Rashba and Dresselhaus SOCs are taken into account. The degree of spin-polarized GH displacement can be tuned by Rashba or Dresselhaus SOC, i.e. interfacial confining electric field or strain engineering. Based on such a semiconductor nanostructure, a controllable spatial spin splitter can be proposed for spintronics applications.

The GMR effect in magnetic–electric barrier nanostructure, which can be realized experimentally by depositing two parallel metallic ferromagnetic strips with an applied voltage on the top of heterostructure, is investigated theoretically. It is shown that a considerable GMR effect can be achieved in such nanosystems due to the significant transmission difference for electrons tunneling through parallel and antiparallel magnetization configurations. It is also shown that the magnetoresistance ratio is strongly dependent upon the applied voltage to metallic ferromagnetic strips in nanosystems, thus may leading to voltage-tunable GMR devices.

We theoretically investigate the giant magnetoresistance (GMR) effect in general magnetically modulated semiconductor nanosystems, which can be realized experimentally by depositing two parallel ferromagnetic strips on the top of a heterostructure. Here the exact magnetic profiles and arbitrary magnetization direction of ferromagnetic strips are emphasized. It is shown that a considerable GMR effect can be achieved in such nanosystems due to the significant transmission difference for electrons tunneling through parallel and antiparallel magnetization configurations. It is also shown that the magnetoresistance ratio is strongly influenced by the magnetization direction of ferromagnetic strips in nanosystems, thus possibly leading to tunable GMR devices.

TREE submodel affiliated with TREEDYN was used to simulate biomass dynamics of Masson pine (Pinus massoniana) forest under different managements (including thinning, clear cutting, combining thinning with clear cutting). The purpose was to represent biomass dynamics involved in its development, which can provide scientific arguments for management of Masson pine forest. The results showed the scenario that 10% or 20% of biomass of the previous year was thinned every five years from 15 to 40 years made total biomass of pine forest increase slowly and it took more time to reach a mature community; If clear cutting and thinning were combined, the case C (clear cutting at 20 years of forest age, thinning 50% of remaining biomass at 30 years of forest age, and thinning 50% of remaining biomass again at 40 years of forest age) was the best scenario which can accelerate speed of development of Masson pine forest and gained better economic values.

The model TREEDEV is developed based on the TREEDYN and TREEGROW models. In TREEDEV model the characteristics and available data of Masson pine (Pinus massoniana) forest in Dinghushan Biosphere Reserve are taken into account as a demonstration. The model was validated by plantation forest and natural forest data. Calculation of tree growth is based on carbon and nitrogen balance, which depends on the photoproduction of its needles, respiration, nitrogen content of all organisms and that in soil, and other losses due to respiration, litterfall and renewal of stem, branch, needle and root. The model includes four aspects: (1) Exogenous driving force solar radiation, which is a function of latitude, specific meteorological conditions and seasonal time. (2) Canopy photoproduction, in this submodel the influence of temperature, solar radiation, seasonal time and nitrogen content of the soil are taken into account. (3) Biomass compartment into needles, fine roots, coarse roots, branches and stems, enabling us to calculate the appropriate respiration demands for the maintenance of the living biomass fractions, fine roots and needles renewal more accurately. (4) The cycle of carbon and nitrogen in soil, which is related to the decomposition and humification of soil organic matter and litter, nitrogen mineralization from litter, and nitrogen leaching. The dynamics of nitrogen include nitrogen uptake demand of the tree, the loss of nitrogen, and nitrogen relocation before litter shedding and the nitrogen supply from soil. Combined with field condition, scenarios involving litter removal and protective fencing were taken into account. Sensitivity analysis was performed in which 43 model independent variables were varied and analyzed in respect to their influence on 22 dependent variables describing forest state. Simulation results showed that litter removal has an influence on the growth of vegetation, which changes the environment, and retards the renewal of litter and reduces the uptake and fixation of available nitrogen, especially to needle and fine root. The forest with low intensity disturbance can be restored if it is fenced within an appropriate time (30 years in this paper), but this retards the maturation time of stands and depreciates the economic value of the wood. In this paper carbon and nitrogen cycles are analyzed in view of physiological processes with the goal of improving forest management planning.

Bothriochloa ischaemum grasslands cover a large area of central China. A total of 81 grassland quadrats of 2 m × 2 m were established randomly in nine counties of central China. Data for species composition, abundance, coverage and height, plus several environmental variables were measured and recorded in each quadrat. Dry biomass and productivity for three associations within three counties were also determined. Species data of importance values were used in the two-way indicator species analysis (TWINSPAN) and the detrended correspondence analysis (DCA) ordination. A total of 11 main grassland associations were distinguished by the TWINSPAN classification; all of them being secondary vegetation. Each association had its own characteristics in composition, structure, productivity and environment. The results of DCA show that the distribution of B. ischaemum grasslands and associated species are closely related to longitude, that is, related to a moisture gradient. Precipitation was one of the most important factors affecting the distribution of the studied grasslands. In addition, topographic factors, such as elevation, aspect, slope and soil types, were also correlated to grassland vegetation. The distribution of grassland associations was consistent to that of their dominant species. TWINSPAN and DCA revealed the same ecological gradients in this study. These grasslands are important for regional development of animal husbandry and economy, although their productivity is not very high. Effective protocols for the conservation and management of B. ischaemum grasslands are needed.

To study whether erythropoietin ( EPO) has the anti-aging effect and the mechanisms of how it effects.5% D-galactose hypodermic injection for 6 weeks to establish the aging model. Divided rats into 5 groups randomly: the normal control (group A), the aging model (group B), the low dosage (1 000 U/ (kg x d)) of recombinant human erythropoietin (rhEPO) intervene (group C), the middle dosage (3 000 U/(kg x d)) of rhEPO intervene (group D) and the high dosage (5 000 U/(kg x d)) of rhEPO intervene (group E), 10 rats in each group. Morris water maze was used to comparing the behavioral indexes. After decapitating the rats, the malonaldehyde (MDA), Na(+)-K+ ATPase, total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) of brain tissue were tested. One rat from each group was selected randomly to observe the hippocampal ultramicrostructure.(1) Compared with group A, the learning and memory ability of group B reduced, the level of MDA, the Na(+)-K+ ATPase, T-AOC and the SOD activities of brain tissue decreased (P0.05), besides, a series of aging changes were observed in the hippocampal ultramicro-structure in group B. (2) Compared with group B, an improved learning and memory ability of group D, a reduced MDA content and an increased activity of Na(+)-K+ ATPase, T-AOC and the SOD activities of brain tissue in group D were also observed with a improved hippocampal ultramicro-structure. (3) The low dosage of rhEPO intervention could against the decrease of the activities of brain Na(+)-K+ ATPase, SOD of aging rat (P0.05), but had no significant effects on the rest of the indicators. The high dosage of rhEPO intervention had no significant improvements on various indicators of aging rats in high dosage of rhEPO intervention group was noticed (P0.05).The middle dosage of EPO has the anti-aging effect, and its mechanisms may be related to enhancing the antioxidant enzymes activity and increasing the antioxidant capacity.

To investigate the effect of Helicobacter pylori (Hp) on platelet activation and coagulation function in patients with acute cerebral infarction.Sixty-six patients with acute cerebral infarction and 50 health individuals were enrolled in the study. Hp antibody,expression of CD62p on platelets and clotting indexes were measured and compared between two groups.The positive rate of Hp-IgG and Hp-CagA in cerebral infarction patients were higher than that in controls (P0.05). The positive rate of CD62p in patients with positive Hp-IgG and Hp-CagA was significantly higher than that in negative patients and also controls (P0.05). The APTT and TT were lower and FIB was higher in patients with positive Hp antibody than those in patients with negative Hp antibody (P0.05),but there was no difference in PT,PTR and INR (P0.05).Hp infection can activate platelets and affect coagulation function,which may be involved in the development of cerebral infarction.

To investigate the characteristics of microglial activation of hippocampus in experimental epileptic rats.Morphological changes and proliferation of OX-42 positive cells were compared at different time points after status of epilepticus (SE) in lithium-pilocarpine induced epileptic rats.OX-42 positive cells were activated after SE, which increased to a peak at 3-7 d and in a relatively stable state at 7-14 d; then gradually decreased after 14d and returned to slightly higher level than previously at 21 d.Inflammatory injury, microglial activation and cell proliferation are closely related after seizures, microglial activation may be an important mechanism in the inflammatory injury of epilepsy.

Objective To investigate the safety and efficacy of recanalization with a broadened therapeutic window for acute occlusion of large cerebral arteries. Methods We assessed 38 patients who underwent the hyper-selective intra-arterial administration of low-dose urokinase, along with mechanical thrombus disruption or mechanical thrombus disruption recanalization (34 stents in 33 patients) of occluded vessels, 20 with onset time-to-treatment (OTT) >6 h (observation group; mean OTT, 20.10 ± 15.67 h) and 18 with OTT ≤6 h (control group). NIHSS scores, mRS scores (≤2) at 3 months, recanalization rates, severe cerebral infarctions on CT, and symptomatic hemorrhagic conversions after surgery were compared. Results Postoperative recanalization rates were 100% in both groups, and other results were equivalent. Conclusions Recanalization at longer OTT was safe and effective with acute occlusions of large cerebral arteries. Time to recanalization could be safely prolonged for up to 20 h in these patients.

To observe the changes in the expression of glucose transporter-3 (GLUT3) in the cerebral cortex of rats during aging and investigate the role of GLUT3 in the aging process of the nervous system.The cerebral tissues were collected from rats of 3, 18, 24, and 30 months old (10 in each age group), and the expression of GLUT3 in the cerebral cortex was detected by immunohistochemistry.Under optical microscope, GLUT3-positive cells were found in every group. Within the age range of 3 to 8 months, GLUT3-positive cells increased significantly with age (P0.01), but at 24-30 months of age, the number of GLUT3-positive cells reduced significant with age (P0.01).The expression changes of GLUT3 ir the cerebral cortex of rats during aging indicate that GLUT3 plays an important role in the maturation and aging of the nervous system.

To investigate the expression of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in hippocampus of rats with aging.Paraffin sections of brain tissue of rats at the age of 3, 18, 24, 30 months were stained by immunohistochemistry, the expression of VEGF and MVD was quantitatively analyzed.Innunohistochemical staining showed that the VEGF-positive cells were mainly pyramidal neuron in hippocampus; the intensity of VEGF-positivity in neuron cells was decreased with the aging (P0.05). The MVD in hippocampus was also decreased with the aging of rats (P0.05).Increasing VEGF contents and improving blood circulation in brain tissue may prevent or treat vascular dementia and cerebrovascular diseases.

To examine the distribution of glucose transport 3 (GLUT 3) in different brain regions of aged rats and to investigate its role in ageing process of the nervous system.The GLUT 3 expression in different brain regions was examined with immunohistochemical method in rats aged 3, 18 and 30 months, respectively.The number of GLUT 3-positive cells varied in the different brain regions in rats of all age groups (P0.01); the CA1 region contained the greatest number of positive cells,and fewer in the motor cortex and cerebellum. The number of GLUT 3-positive cells was reduced in the brain of aged rats (P0.01); and the neural cells in 4 different brain regions presented with large cell body and loose alignment.The expression of GLUT 3 decreased in aged rats, which suggests that GLUT 3 may be involved in the ageing process of nervous system.

To identify the changes of expression of p38MAPK in the olfactory bulb (OB) of rats with Alzheimer's Disease (AD) and to explore the functional mechanism of p38MAPK in the pathological changes of AD.AD animal model was established by injecting amyloid-beta peptide 25-35 into the lateral cerebral ventricle of rats. The learning and memory abilities of rats were measured by Y-maze experiment. The expressions of p38MAPK in the OBs of rats in the AD group, saline control group, p38MAPK inhibitor group and inhibitor control (con-inhibitor) group were examined by immunohistochemistry.(1) The capabilities of learning and memory of the rats were impaired significantly at day 7 and day 14 after the induction of AD. Significant learning and memory differences were found (P0.05) between the AD group and the other groups. (2) The expression of p38MAPK in the OBs of rats was found at day 4 after the induction of AD. The expression increased with time. The AD rats had more positive p38MAPK cells than those in the saline controls (P0.05). The expression of phospho-p38MAPK in the rats with AD increased significantly (P0.01) compared with those in the saline group. The AD rats treated with p38MAPK inhibitor had less expression of phospho-p38MAPK than those in the AD group and the inhibitor control (P0.01). CONCLUSIONS; Abeta25-35 can activate p38MAPK signal transduction pathway. p38MAPK may play a role in the formation of dysosmia in AD. SB203580, a p38MAPK inhibitor, can reduce the neurotoxicity evoked by p38MAPK.

To reveal the expression trends of HIF-1alpha in hippocampus of different age rats, investigate the role of HIF-1alpha in the aging process of nervous system.The cerebral tissues was collectd from rats of different age, including 3, 18, 24, 36 months old. There were 6 rats in each age group. The expressions of nissl body and HIF-1alpha in different part of hippocampus were observed by nissl staining and immunohistochemical technique.(1) With the increase of rat age, nerve cells appeared to be bigger and to arrange sparsely, while the nissl body decreased; (2) The positive HIF-1alpha staining cells in CA1, CA3 region of hippocampus increased along with the increase of rat age. The difference between any two age groups showed statistical significance (P0.05).The function of protein synthesis weakened in nerve cells but the expression of HIF-1alpha increased with the age increasing, which may play an important role in aging of nervous system.

To investigate the expression of Redox factor-1(Ref-1) in rats with Alzheimer's disease (AD).AD rat model was established by a single injection of beta-amyloid peptide (Abeta25-35) into the lateral cerebral ventricle of rats. Y-shape maze task was conducted to check the ethology. At 4th, 7th and 14th day after injection, Ref-1 expression in hippocampus CA1 area was detected by immunohistochemistry.The numbers of repeated learning and error and the total reaction time in AD group were significantly higher than those in control group at 7th and 14th day after injection of Abeta25-35 (P0.05). At 4th day after injection of Abeta25-35, the Ref-1 expression was increased with time prolongation in AD group(P0.01).Injection of Abeta25-35 in lateral cerebral ventricle can decrease the learning and memory abilities of rats, and results also indicate that Ref-1 expression in hippocampus may be involved in the development of AD.

To observe the distribution of hypoxia inducible factor-1alpha (HIF-1alpha) in different brain regions in aged rats and investigate the role of HIF-1alpha in the aging process of the nervous system.The Nissl bodies and HIF-1alpha expression in different brain regions were observed in rats aged 3 and 30 months using Nissl staining and immunohistochemical method, respectively.In the 30-month-old rats, the neural cells in 4 different brain regions presented with large cell body and loose alignment, containing reduced Nissl bodies in the cytoplasm. Compared with the 3-month-old rats, the aged rats showed greater number of HIF-1alpha-positive cells in the brain (P0.01), and the number varied significantly between the different brain regions (P0.01). The CA3 region contained the greatest number of positive cells, which were fewer in the motor cortex and cerebellum.The capacity for protein synthesis in the neural cells is weakened but the expression of HIF-1alpha increased in aged rats, suggesting the important role that HIF-1alpha may play in the aging process of the nervous system, especially in hypomnesis.

To observe the effect of puerarin on the learning-memory disorder after global cerebral ischemia-reperfusion injury in rats, and to explore its mechanism of action.The global cerebral ischemia-reperfusion injury model was established using the modifified Pulsinelli four-vessel occlusion in Sprague-Dawley rats. Rats were intraperitoneally injected with puerarin (100 mg/kg) 1 h before ischemia and once every 6 h afterwards. The learning-memory ability was evaluated by the passive avoidance test. The dynamic changes of the cell counts of apoptosis and positive expression of Bcl-2 in the hippocampus CA1 region were determined by the TUNEL and immunohistochemical methods, respectively.(1) Compared with the reperfusion group, the step through latency (STL) in the passive avoidance test in the puerarin group was prolonged signifificantly (P0.01). (2) The apoptotic neurons were injured most severely on the 3rd day in the hippocampal CA1 region after global ischemia and reperfusion. In the puerarin group, the number of apoptotic cells decreased at respective time points after ischemia-reperfusion (P0.01). (3) The level of positive expression of Bcl-2 varied according to the duration of reperfusion and the peak level occurred on day 1 in the hippocampal CA1 region after global cerebral ischemia. Compared with the reperfusion group, the expression of Bcl-2 in the puerarin group was up-regulated at the respective time points after ischemia reperfusion (P0.01), reaching the peak on day 1.Puerarin could improve the learning-memory ability after global cerebral ischemia and reperfusion in rats. The protective mechanism might be related to the effect of inhibiting or delaying the cell apoptosis through up-regulating the expression of Bcl-2 after ischemia and reperfusion.

To observe the expression rule of hypoxia inducible factor-1 (HIF-1alpha) and erythropoietion (EPO) in the formation of vascular dementia (VD) and investigate the possible pathogenesis of VD.Rats of experimental group were treated with a permanent bilateral common carotid arteries (CCA) occlusion (2-VO) for establishing vascular dementia model. Rats were evaluated on learning-memory ability by Y-type water maze test. The dynamic expression of HIF-1alpha and EPO in hippocampal CA1 region were measured by immunohistochemical assay method.(1) The learning-memory ability of rats in VD groups was progressively decreased as the ischemic duration prolonged (P0.05); (2) In VD group, the expression of HIF-1alpha and EPO in hippocampal CA1 region were most obvious at 1 w, and then declined progressively but still above the normal level (P0.01); (3) In VD group, the expression of HIF-1alpha and EPO at each ischemic point and their corresponding learning-memory ability were in significant correlation at the 0.01 level.Both HIF-1alpha and EPO contribute to the formation of VD, and HIF-1/EPO anoxic signal transduction may play a protecting role in this process.

With the help of stationary phase method, we investigate the Goos-Hanchen (GH) effect of electrons in nanostructures consisting of realistic magnetic barriers (MB) created by lithographic patterning of ferromagnetic (FM) or superconducting films. Due to intrinsic symmetry, only nanostructures with symmetric magnetic field possess a considerable spin-dependent GH effect, and GH shifts of transmitted spin beams are found to depend upon the incident angle and the incident energy of electrons as well as the size and position of the FM stripe. These interesting properties may provide an effective scheme to realize spin injection into semiconductor and also give rise to a type of spin beam splitters based on MB nanostructures.

We propose a giant magnetoresistance (GMR) device by depositing nanosized ferromagnetic (FM) and Schottky normal metal (SM) stripes on the top of the GaAs heterostructure. It is shown that this device possesses a considerable GMR effect, whose magnetoresistance (MR) ratio can be up to 106% at a certain energy. It is also shown that the MR ratio depends strongly on the structural parameters and the electrical barrier height induced by the applied voltage to the SM stripe, and thus this device can be used as a tunable GMR device.

The giant magnetoresistance (GMR) effect in a device, composed of nanosized ferromagnetic (FM)-Schottky metals (SM) and semiconductor heterostructure, is investigated theoretically. Experimentally, this GMR device can be realized by the deposition of two parallel FM strips and a SM stripe on the top of a GaAs heterostructure. It is shown that the GMR effect ascribes a significant electron transmission difference between the parallel and antiparallel magnetization configurations of two FM stripes in the device. It is also shown that the magnetoresistance (MR) ratio depends strongly on the magnetic intensity of the magnetic barrier (MB) and the electric-barrier (EB) height induced by an applied voltage to the SM stripe. Thus, this device can be used as a tunable GMR one, whose MR ratio can be switched by adjusting the applied voltage under the SM stripe or by changing the magnetic strength of the MB.