Effects of incorporation of Ag into a kesterite Cu2ZnSnS4 thin film on its photoelectrochemical properties for water reduction.

Kesterite Cu2ZnSnS4 (CZTS) thin films in which the Cu site was partially replaced with Ag were prepared by spray deposition on an Mo-coated glass substrate. Successful replacement of Cu components in the CZTS lattice with Ag up to an Ag/(Cu + Ag) ratio of 0.20 was achieved. Samples with relatively low contents of Ag (Ag/(Cu + Ag) ratios of 0.05 and 0.10) showed obvious grain growth compared to that of bare CZTS, whereas samples with higher Ag contents showed an appreciable decrease in grain sizes. Photoelectrochemical properties for water reduction (H2 production), which was examined after surface modifications with an In2S3/CdS double layer and Pt catalyst for H2 evolution, depended strongly on such morphological differences; a maximum conversion efficiency, i.e., half-cell solar to hydrogen efficiency, of 2.4% was achieved by the photocathode based on the film with an Ag/(Cu + Ag) ratio of 0.10. Minority carrier dynamics examined by photoluminescence measurements indicated that such an active sample of PEC H2 production had a relatively long carrier lifetime, suggesting that the suppression of carrier recombination at grain boundaries in the bulk of these kesterite films is one of the important factors for enhancing PEC functions.

Differences in Hemodynamic Alteration between Atherosclerotic Occlusive Lesions and Moyamoya Disease: A Quantitative 15O-PET Study.

To clarify the differences in hemodynamic status between atherosclerotic steno-occlusive lesions (SOL) and moyamoaya disease (MMD), hemodynamic parameters were compared using 15O-PET. Twenty-four patients with unilateral SOL (67 ± 11 y) and eighteen with MMD (33 ± 16 y) were assigned to this study. MMD patients were divided into twelve unilateral and six bilateral lesions. All patients underwent 15O-PET to measure cerebral blood flow (CBF), blood volume (CBV), oxygen extraction fraction (OEF), and metabolic rate (CMRO2). Acetazolamide was administered after the baseline scan and the second 15O-water PET was performed to evaluate cerebrovascular reactivity (CVR). For the CBF calculation in 15O-water PET, the three-weighted integral method was applied based on a one-tissue compartment model with pixel-by-pixel delay correction to measure precise CBF and arterial-to-capillary blood volume (V0). Baseline hemodynamic parameters showed significantly lower CBF, V0, and CMRO2, but greater CBV, OEF, and delay (p < 0.01) in the affected hemispheres than in the unaffected hemispheres. After ACZ administration, both hemispheres showed a significant increase in CBF (p < 0.0001), but not in V0. CVR differed significantly between the hemispheres. The arterial perfusion pressure of the functioning arterial part tended to be reduced after acetazolamide administration in patients with past neurologic events caused by hemodynamic impairment. MMD patients showed greater inactive vascular and venous volumes compared with common atherosclerotic SOL patients. The hemodynamic status of cerebral circulation may vary according to the chronic process of steno-occlusive change and the development of collateral circulation. In order to evaluate physiologic differences between the two diseases, 15O-PET with an acetazolamide challenge test is useful.

A Novel Automatic Approach for Calculation of the Specific Binding Ratio in [I-123]FP-CIT SPECT.

A fully automatic method for specific binding ratio (SBR) calculation in [123I]ioflupane single-photon emission computed tomography (SPECT) studies was proposed by creating volumes of interest of the striatum (VOIst) and reference region (VOIref) without manual handling to avoid operator-induced variability. The study involved 105 patients (72 ± 10 years) suspected of parkinsonian syndrome (PS) who underwent [123I]ioflupane SPECT. The 200 images from our previous study were used for evaluation and validation of the new program. All patients were classified into PS and non-PS groups according to the results of clinical follow-up. A trapezoidal volume of interest (VOIt) containing all striatal intensive counts was created automatically, followed by VOIst setting using the previous method. SBR values were calculated from the mean values of VOIst and VOIref determined by the whole brain outside of VOIt. The low count voxels in the VOIref were excluded using an appropriate threshold. The SBR values from the new method were compared with the previous semi-automatic method and the Tossici-Bolt (TB) method. The SBRs from the semi- and fully automatic methods showed a good linear correlation (r > 0.98). The areas under the curves (AUCs) of receiver operating characteristic analysis showed no significant difference between the two methods for both our previous (AUC > 0.99) and new (AUC > 0.95) data. The diagnostic accuracy of the two methods showed similar results (>92%), and both were better than the TB method. The proposed method successfully created the automatic VOIs and calculated SBR rapidly (9 ± 1 s/patient), avoiding operator-induced variability and providing objective SBR results.

Count-based method for specific binding ratio calculation in [I-123]FP-CIT SPECT analysis.

OBJECTIVE: To calculate the specific binding ratio (SBR) appropriately in dopamine transporter (DAT) imaging, a method for extracting the striatal volume of interest (VOI) was developed. METHODS: This study included 200 patients (72 ± 10 years) who were suspected of parkinsonian syndromes (PS) or dementia with Lewy body (DLB). The patients were divided into three groups of PS with dopaminergic degeneration, DLB and non-PS after [123I]ioflupane (FP-CIT) SPECT and clinical follow-up. The image data were reconstructed with CT attenuation correction and scatter correction, and with only CT attenuation correction (CTAC). The new method extracted striatal VOI according to the high-level counts and the average striatum volume, and calculated SBR using the reference occipital counts. The SBR values for each patient were obtained using the Tossici-Bolt method (SBRBolt) and our method. Reproducibility of SBR calculation using our method was compared by two operators. RESULTS: The mean SBR values for the PS and DLB groups were significantly different from that of the non-PS group with both methods. The coefficients of variation of the SBR were significantly smaller with the proposed method compared with those of SBRBolt (p < 0.001), except for the CTAC images. There were no differences in SBR between the two operators using our method. The diagnostic accuracies with our method for the PS and DLB groups were 98.4 and 96.0%, respectively. CONCLUSION: Our new method for SBR calculation in the FP-CIT SPECT showed less coefficients of variation with high reproducibility, which would be useful for clinical diagnosis and in assessing the severity of diseases in follow-up studies.

Effects of Zirconium Doping Into a Monoclinic Scheelite BiVO4 Crystal on Its Structural, Photocatalytic, and Photoelectrochemical Properties.

Effects of zirconium (Zr) doping into BiVO4 powder on its structural properties and photocatalytic activity for O2 evolution were examined. The formation of BiVO4 powder crystallized in a monoclinic scheelite structure (ms-BiVO4) was achieved when the sample was doped with a relatively small amount of Zr. The photocatalytic activity of Zr-doped ms-BiVO4 powder was much higher than that of non-doped ms-BiVO4. However, further doping caused a reduction of photocatalytic activity for O2 evolution due to the occurrence of structural alterations into tetragonal scheelite and tetragonal zircon structures. Similar effects of Zr doping were also observed for the photoelectrochemical (PEC) system based on BiVO4 thin films doped with various amounts of Zr. Thus, Zr doping was confirmed to be effective for improvements of photocatalytic and PEC functions of BiVO4 for water oxidation.

Pixel-by-pixel precise delay correction for measurement of cerebral hemodynamic parameters in H215O PET study.

OBJECTIVE: A new method of delay time estimation was proposed to measure precise cerebral blood flow (CBF) and arterial-to-capillary blood volume (V 0) using 15O-water PET. METHODS: Nineteen patients with unilateral arterial stenoocclusive lesions were studied to evaluate hemodynamic status before treatment. The delay time of each pixel was calculated using least squares fitting with an arterial blood input curve adjusted to the internal carotid artery counts at the skull base. Pixel-by-pixel delay estimation provided a delay map image that could be used for precise calculation of CBF and V 0 using a one-tissue compartment model, and the values from this method were compared with those from the slice-by-slice correction method. RESULTS: The affected side showed a longer delay time than the contralateral cerebral hemisphere. Although the mean cortical CBF values were not different between the two methods, the slice-by-slice delay correction overestimated CBF in the hypo perfused area. The scatter plot of V 0 pixel values showed significant difference between the two correction methods where the slice-by-slice delay correction significantly overestimated V 0 in the whole brain (P < 0.05). CONCLUSION: Pixel-by-pixel delay correction provides delay images as well as better estimation of CBF and V 0, thus offering useful and beneficial information for the treatment of cerebrovascular disease.

Peptides mimicking Vibrio cholerae O139 capsular polysaccharide elicit protective antibody response.

Vibrio cholerae is the etiological agent of cholera. V. cholerae serogroup O1 had been, until 1992, the only serogroup responsible for large epidemics and pandemics of cholera. In 1992, a new serotype of V. cholerae emerged in South-East Asia that caused a massive outbreak of cholera in India and neighboring countries. The new serotype was named V. cholerae O139. The main differences between V. cholerae O139 and O1 are that the former possesses a capsular polysaccharide and different lipopolysaccharide. Capsular polysaccharides are, in general, T-independent antigens giving rise to poor immune responses lacking immunological memory. In order to overcome this, monoclonal antibodies against the capsular polysaccharide of V. cholerae O139 were used to screen different phage-displayed random peptide libraries. Eight different phage clones were selected and characterized using enzyme immunoassay with the monoclonal antibodies, and then tested for specificity by competition with V. cholerae O139 capsular polysaccharide. Selected peptides were sequenced, synthesized and conjugated to bovine serum albumin (BSA) and keyhole limpet hemocyanin (KLH). The conjugated peptides were used to immunize mice. It is evident that the anti-peptide mouse antibodies bind to the V. cholerae O139 capsular polysaccharide. In addition, the anti-peptide antibodies are protective in a suckling mouse model. The protective efficacy is both specific and dose-dependent. A PCT (PCT/IT2003/000489) with the publication number WO 2004/056851 has been filed for the sequences of the eight peptides.