Comparative Studies of Effects of Vapor- and Liquid-Phase As2O3 on Catalytic Behaviors of V2O5-WO3/TiO2 Catalysts for NH3-SCR.

The role of vapor- and liquid-phase As2O3 in deactivating commercial V2O5-WO3/TiO2 catalyst during the NH3-selective catalytic reduction (SCR) process was explored and compared. As2O3 was loaded via vapor deposition (As(vap)) and the wet impregnation (As(imp)) method, respectively. Results demonstrated that the poisoning extent of vapor arsenic was much stronger than in the liquid state. Differences in As distribution on the catalyst surface was one of the main causes. Most vapor As2O3 could be oxidized to As2O5, which underwent stacking and formed a dense covering layer on the catalyst surface. In comparison, liquid As2O3 could also be oxidized but distributed uniformly and did not change the catalyst pore structure. Loading arsenic would destroy the V-OH and V=O active sites of the catalyst, and less reactive As5+-OH was generated. Catalyst oxidizability was also enhanced, resulting in NH3 oxidation enhancement, decreased N2 selectivity, and a decline in SCR activity. Importantly, the intermediate of NH3 oxidation, NH2-amide, also could react with NO + O2, and more N2O was generated on the poisoned catalyst during the SCR process, especially on As(imp). Finally, two mechanisms of arsenic poisoning were proposed, in which the role of vapor and liquid As2O3 over the V2O5-WO3/TiO2 catalyst was compared.

Predictive Value of Preoperative Multidetector-Row Computed Tomography for Axillary Lymph Nodes Metastasis in Patients With Breast Cancer.

Introduction: Axillary lymph nodes (ALN) status is an essential component in tumor staging and treatment planning for patients with breast cancer. The aim of present study was to evaluate the predictive value of preoperative multidetector-row computed tomography (MDCT) for ALN metastasis in breast cancer patients. Methods: A total of 148 cases underwent preoperative MDCT examination and ALN surgery were eligible for the study. Logistic regression analysis of MDCT variates was used to estimate independent predictive factors for ALN metastasis. The prediction of ALN metastasis was determined with MDCT variates through receiver operating characteristic (ROC) analysis. Results: Among the 148 cases, 61 (41.2%) cases had ALN metastasis. The cortical thickness in metastatic ALN was significantly thicker than that in non-metastatic ALN (7.5 ± 5.0 mm vs. 2.6 ± 2.8 mm, P < 0.001). Multi-logistic regression analysis indicated that cortical thickness of >3 mm (OR: 12.32, 95% CI: 4.50-33.75, P < 0.001) and non-fatty hilum (OR: 5.38, 95% CI: 1.51-19.19, P = 0.009) were independent predictors for ALN metastasis. The sensitivity, specificity and AUC of MDCT for ALN metastasis prediction based on combined-variated analysis were 85.3%, 87.4%, and 0.893 (95% CI: 0.832-0.938, P < 0.001), respectively. Conclusions: Cortical thickness (>3 mm) and non-fatty hilum of MDCT were independent predictors for ALN metastasis. MDCT is a potent imaging tool for predicting ALN metastasis in breast cancer. Future prospective study on the value of contrast enhanced MDCT in preoperative ALN evaluation is warranted.

Spatial working memory impairment in subclinical hypothyroidism: an FMRI study.

OBJECTIVE: Using a block-designed BOLD-fMRI to explore the neural basis of spatial working memory impairment in patients with subclinical hypothyroidism (SCH) performing an n-back task. METHODS: Sixteen patients with SCH before and after being treated with levothyroxine (LT4) for 6 months and 16 matched euthyroid subjects were scanned by fMRI under the n-back task. RESULTS: The fMRI scan found that a neural network consisting of bilateral dorsolateral prefrontal cortex (DLPFC), bilateral premotor area (PreMA), supplementary motor area/anterior cingulate cortex, bilateral parietal lobe (PA) and right caudate nucleus/thalamus was activated, with right hemisphere dominance. In euthyroid subjects, all these regions of interest (ROIs) showed load effect; however, only left DLPFC, left PA, bilateral PreMA and right caudate nucleus/thalamus showed the same effect in Pre-SCH patients. Furthermore, activation intensities of most ROIs (especially DLPFC and right PA) for Pre-SCH patients were lower than those in the euthyroid subjects (F <3.046, p > 0.062). Importantly, after a 6-month treatment with LT4, the load effect in SCH patients appeared the same as in the euthyroid subjects in all the ROIs (F >13.176, p < 0.0001). CONCLUSION: Our previous study shows that verbal working memory of SCH patients is impaired with abnormal activity in bilateral frontal areas. In this study, the results indicated that SCH patients may also have spatial working memory impairments, and the altered activities of right DLPFC and right posterior parietal lobe may be one of the underlying neural mechanisms. Most importantly, this study shows that LT4 replacement therapy can improve the memory impairment and reverse the altered neural activity network.

Functional magnetic resonance imaging of methamphetamine craving.

The study aimed to explore the abnormal activation of special brain areas associated with methamphetamine craving using functional magnetic resonance imaging (fMRI) and to reveal the neurobiological basis of addiction. Twenty-six methamphetamine addicts and 26 healthy subjects were scanned by brain fMRI while watching pictures of happy, sad, or methamphetamine to acquire resource data. SPM5 was used to analyze fMRI data to get related brain activation map, and it was found that methamphetamine addicts had high brain activation in cingulate and low activation in frontal lobe when watching methamphetamine-cue pictures. This study demonstrated that methamphetamine addicts had emotion-related brain activation abnormalities.