Electronic-dimensionality reduction of bulk MoS2 by hydrogen treatment.

A reduction in the electronic-dimensionality of materials is one method for achieving improvements in material properties. Here, a reduction in electronic-dimensionality is demonstrated using a simple hydrogen treatment technique. Quantum well states from hydrogen-treated bulk 2H-MoS2 are observed using angle resolved photoemission spectroscopy (ARPES). The electronic states are confined within a few MoS2 layers after the hydrogen treatment. A significant reduction in the band-gap can also be achieved after the hydrogen treatment, and both phenomena can be explained by the formation of sulfur vacancies generated by the chemical reaction between sulfur and hydrogen.

Electron Number-Based Phase Diagram of Pr_{1-x}LaCe_{x}CuO_{4-δ} and Possible Absence of Disparity between Electron- and Hole-Doped Cuprate Phase Diagrams.

We performed annealing and angle resolved photoemission spectroscopy studies on electron-doped cuprate Pr_{1-x}LaCe_{x}CuO_{4-δ} (PLCCO). It is found that the optimal annealing condition is dependent on the Ce content x. The electron number (n) is estimated from the experimentally obtained Fermi surface volume for x=0.10, 0.15 and 0.18 samples. It clearly shows a significant and annealing dependent deviation from the nominal x. In addition, we observe that the pseudo-gap at hot spots is also closely correlated with n; the pseudogap gradually closes as n increases. We established a new phase diagram of PLCCO as a function of n. Different from the x-based one, the new phase diagram shows similar antiferromagnetic and superconducting phases to those of hole doped ones. Our results raise a possibility for absence of disparity between the phase diagrams of electron- and hole-doped cuprates.

Preoperative evaluation of venous systems with 3-dimensional contrast-enhanced magnetic resonance venography in brain tumors: comparison with time-of-flight magnetic resonance venography and digital subtraction angiography.

BACKGROUND: Recent developments in magnetic resonance (MR) technology now enable the use of MR venography, providing 3-dimensional (3D) images of intracranial venous structures. The purpose of this study was to assess the usefulness of 3D contrast-enhanced MR venography (CE MRV) in the evaluation of intracranial venous system for surgical planning of brain tumors. METHODS: Forty patients underwent 3D CE MRV, as well as 25 patients, 2-dimensional (2D) time-of-flight (TOF) MR venography in axial and sagittal planes; and 10 patients, digital subtraction angiography. We determined the number of visualized sinuses and cortical veins. Degree of visualization of the intracranial venous system on 3D CE MRV was compared with that of 2D TOF MR venography and digital subtraction angiography as a standard. We also assessed the value of 3D CE MRV in the investigation of sinus occlusion or localization of cortical draining veins preoperatively. RESULTS: Superficial cortical veins and the dural sinus were better visualized on 3D CE MRV than on 2D TOF MR venography. Both MR venographic techniques visualized superior sagittal sinus, lateral sinus, sigmoid sinus, straight sinus, and internal cerebral vein and provided more detailed information by showing obstructed sinuses in brain tumors. Only 3D CE MRV showed superficial cortical draining veins. However, it was difficult to accurately evaluate the presence of cortical collateral venous drainage. CONCLUSION: Although we do not yet advocate MR venography to replace conventional angiography as the imaging standard for brain tumors, 3D CE MRV can be regarded as a valuable diagnostic method just in evaluating the status of major sinuses and localization of the cortical draining veins.

Assessment of cerebrocortical regions associated with sexual arousal in premenopausal and menopausal women by using BOLD-based functional MRI.

PURPOSE: The aim of this study was to compare the cerebral regions associated with sexual arousal between premenopausal and menopausal women by using functional magnetic resonance imaging (f MRI). MATERIALS AND METHODS: Ten premenopausal and 10 menopausal women underwent fMRI on a 1.5T MR scanner using the blood oxygen level dependent technique. To identify the activated brain regions associated with sexual response, brain activation was assessed during 1 minute of a nonerotic film, followed by 4 minutes of an erotic film. RESULTS: The overall activation ratios of the premenopausal women were greater than those of the menopausal women by approximately 8% on average. The limbic, temporal association areas, and parietal lobe showed greater enhancement of signal intensities in premenopausal women. However, signal enhancement in the genu of the corpus callosum and superior frontal gyrus was dominant in menopausal women. CONCLUSIONS: The activated brain center associated with visually evoked sexual arousal showed qualitative and quantitative differences between premenopausal and menopausal women.

Prognostication of recovery in patients with acute ischemic stroke through the use of brain SPECT with Technetium-99m--labeled metronidazole.

BACKGROUND AND PURPOSE: We hypothesized that technetium-99m-ethylene dicysteine-metronidazole (99mTc-EC-MN) localizes to brain tissue that is hypoxic but viable. This study prospectively evaluated the relationship between neurological outcome and uptake of 99mTc-EC-MN in peri-infarcted regions of the brain. METHODS: Eight patients with acute ischemic stroke in the territory of the left middle cerebral artery underwent 99mTc-EC-MN and 99mTc-ethyl cysteinate dimer (ECD) brain SPECTs on the same day during the subacute stage (10.3+/-2.5 days). The infarct volumes from 99mTc-ECD images (IV(ECD)), infarct volumes from diffusion-weighted MRI images (IV(DW)), and hypoxic volume (HV) from 99mTc-EC-MN images were calculated. The net infarct volume (NIV(ECD)) was defined as IV(ECD) minus HV. The National Institutes of Health Stroke Scale scores were measured on admission and days 1, 3, 7, and 30. RESULTS: IV(ECD) was greater than IV(DW). The lesion-to-normal count-density ratios of 99mTc-EC-MN ranged from 1.80 to 5.96. HV was 60.2+/-65.2 cm3, and the mean percent HV was 24.5+/-28.1% of IV(ECD). NIV(ECD) was 162.6+/-133.4 cm3 and was significantly smaller than IV(ECD). NIV(ECD) was significantly correlated with National Institutes of Health Stroke Scale score at 1 month and was a significant predictor of neurological deficit at 1 month. CONCLUSIONS: 99mTc-EC-MN brain SPECT can detect hypoxic tissue after acute ischemic stroke and, in combination with 99mTc-ECD brain SPECT, is useful in predicting neurological outcome in ischemic stroke patients.

Neovascular glaucoma associated with cilioretinal artery occlusion combined with perfused central retinal vein occlusion.

BACKGROUND: Cilioretinal artery occlusion rarely results in neovascular glaucoma, especially in cases of extensive cilioretinal infarction and combined retinal vascular occlusion. CASE: A 62-year-old man with diabetes mellitus and essential hypertension showed a visual acuity of counting fingers, retinal whitening temporal to the optic disc with mild dilation and tortuosity of the retinal veins, and retinal hemorrhages in four quadrants of his right eye. Fluorescein angiography demonstrated a delayed filling of the central retinal vein and cilioretinal artery. OBSERVATIONS: Two months later, neovascular glaucoma developed and retinal ablation was performed using an argon laser. Trabeculectomy was also performed due to the intractability of the glaucoma, and central artery occlusion was found. On magnetic resonance angiography, the right distal common carotid artery was irregularly narrowed and the right ophthalmic artery was almost entirely occluded. CONCLUSIONS: In cases of cilioretinal artery occlusion and perfused central retinal vein occlusion with multiple risk factors, close follow-up is advised.