Residual stress, microstructure, and structure of tungsten thin films deposited by magnetron sputtering Sputter-deposited W films with nominal thicknesses between 5 and 180 nm were prepared by varying the base pressure prior to film deposition and by including or not including sputtered SiO 2 encapsulation layers. X-ray and electron diffraction studies showed that single phase, polycrystalline a-W could be achieved in as-deposited films as thin as 5 nm. The stress state in the as-deposited films was found to be inhomogeneous. Annealing resulted in stress relaxation and reduction of resistivity for all films, except the thinnest, unencapsulated film, which agglomerated. In-plane film grain sizes measured for a subset of the annealed films with thicknesses between 5 and 180 nm surprisingly showed a near constant value (101-116 nm), independent of film thickness. Thick-film (!120 nm) resistivity values as low as 8.6 lX cm at 301 K were obtained after annealing at 850 C for 2 h. Film resistivities were found to increase with decreasing film thicknesses below 120 nm, even for films which are fully A2 a-W with no metastable, A15 b-W evident.
To further investigate and improve upon current stroke models in nonhuman primates, infarct size, neurologic function and survival were evaluated in two endovascular ischemic models in sixteen rhesus monkeys. The first method utilized a micro-catheter or an inflatable balloon to occlude the M1 segment in six monkeys. In the second model, an autologous clot was injected via a micro-catheter into the M1 segment in ten monkeys. MRI scanning was performed on all monkeys both at baseline and 3 hours after the onset of ischemia. Spetzler neurologic functions were assessed post-operatively, and selective perfusion deficits were confirmed by DSA and MRI in all monkeys. Animals undergoing micro-catheter or balloon occlusion demonstrated more profound hemiparesis, larger infarct sizes, lower Spetzler neurologic scores and increased mortality compared to the thrombus occlusion group. In animals injected with the clot, there was no evidence of dissolution, and the thrombus was either near the injection site (M1) or flushed into the superior division of the MCA (M2). All animals survived the M2 occlusion. M1 occlusion with thrombus generated 50% mortality. This study highlighted clinically important differences in these two models, providing a platform for further study of a translational thromboembolic model of acute ischemic stroke.
We demonstrate an angular high-harmonic spectroscopy (HHS) method to probe the spinning dynamics of molecular rotational wave packet (RWP) in real time. With the excitation of two timedelayed, polarization-skewed pump pulses, the molecular ensemble is impulsively kicked to rotate unidirectionally, which is subsequently irradiated by another delayed probe pulse for high-order harmonic generation (HHG). The spatiotemporal evolution of the molecular RWP is visualized from the time-dependent angular distributions of the HHG yields and frequency shift measured at various polarization directions and time delays of the probe pulse. The observed frequency shift in HHG is demonstrated to arise from the nonadiabatic effect induced by molecular spinning. Different from the previous spectroscopic and Coulomb explosion imaging techniques, the angular HHS method can reveal additionally the electronic structure and multiple orbitals of the sampled molecule. All the experimental findings are well reproduced by numerical simulations. Further extension of this method would provide a powerful tool for probing complex polyatomic molecules with HHG spectroscopy.
Local infusion of ice-cold lactated Ringer's solution via micro-catheter is a safe and effective method for selective cerebral hypothermia. This cooling method could potentially be developed as a new treatment in acute ischemic stroke.
Electron migration in molecules is the progenitor of chemical reactions and biological functions after light-matter interaction. Following this ultrafast dynamics, however, has been an enduring endeavor. Here we demonstrate that, by using machine learning algorithm to analyze high-order harmonics generated by two-color laser pulses, we are able to retrieve the complex amplitudes and phases of harmonics of single fixed-in-space molecules. These complex dipoles enable us to construct movies of laser-driven electron migration after tunnel ionization of N2 and CO2 molecules at time steps of 50 attoseconds. Moreover, the angular dependence of the migration dynamics is fully resolved. By examining the movies, we observe that electron holes do not just migrate along the laser polarization direction, but may swirl around the atom centers. Our result establishes a general scheme for studying ultrafast electron dynamics in molecules, paving a way for further advance in tracing and controlling photochemical reactions by femtosecond lasers.
Artesunate is a semi-synthetic derivative of artemisinin that is used in the treatment of patients with malaria. Artesunate has also been reported to exert immune‑regulatory, antitumor, hepatoprotective, anti‑inflammatory and smooth muscle relaxing functions. The present study aimed to investigate the putative protective effects of artesunate against cerebral ischemia/reperfusion injury (CIRI), and to elucidate the molecular mechanisms underlying its effects. A CIRI mouse model was created via middle cerebral artery occlusion for 2 h, followed by 22 h of reperfusion. Mice were treated with 10‑40 mg/kg artesunate. The present results demonstrated that treatment with artesunate significantly reduced the cerebral infarct volume and potentiated the recovery of neurological function in CIRI mice. Oxidative stress and inflammation markers were revealed to be significantly downregulated following treatment with artesunate in CIRI mice. Furthermore, artesunate was demonstrated to activate nuclear factor erythroid 2‑related factor 2 (Nrf2), inhibit caspase‑3 activity, reduce the apoptosis regulator BAX/apoptosis regulator Bcl‑2 expression ratio and suppress the phosphorylation of the mitogen‑activated protein kinase (MAPK) p38 in CIRI mice. In conclusion, the present findings suggested that artesunate may exert protective effects against CIRI through the suppression of oxidative and inflammatory processes, via activating Nrf2 and downregulating ROS‑dependent p38 MAPK in mice.
Supramolecular hydrogels derived from natural biomolecules have promising applications for drug delivery due to their inherent biocompatibility and tunable responsiveness to various stimuli. However, conventional hydrogels only modulate the release...
Abstract. The aim of this study was to investigate whether the SIRT1 exerts neuroprotective effects by attenuating cerebral ischemia/reperfusion-induced injury (CIRI) via targeting p53/microRNA-22. We found that the overexpression of sirtuin 1 (SIRT1) decreased the infarct volume, suppressed p53 protein expression and activated microRNA-22 expression following CIRI. An injection of lipopolysaccharide (LPS, 1 mg/ml; Sigma, St. Louis, MO USA) into the corpus callosum was used to induce CIRI in rats. The infarct volume and neurological deficit score were used to examine the effects of SIRT1 on CIRI. Furthermore, the overexpression of SIRT1 was found to suppress caspase-3 activity, inhibit the activation of the Bax signaling pathway, reduce tumor necrosis factor-α (TNF-α) and interleukin (IL)-6) activity, decrease cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) protein expression, and increase IL-10 activity following CIRI. Following the downregulation of SIRT1, p53 protein expression was significantly increased, microRNA-22 expression was inhibited, caspase-3 activity was increased and the Bax signaling pathway was activated. In addition, the activity of TNF-α and IL-6 was was enhanced, COX-2 and iNOS protein expression was increased, and IL-10 activity was reduced following CIRI. Thus, the data from our study suggest that SIRT1 attenuates CIRI by targeting the p53/microRNA-22 axix, while suppressing apoptosis, inflammation, COX-2 and iNOS expression.
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