Activating lattice oxygen of single-layer ZnO for the catalytic oxidation reaction.

Tuning an oxide/metal interface is of critical importance for the performance enhancement of many heterogeneous catalytic reactions. However, catalytic oxidation occurring at the interface between non-reducible oxide and metal has been challenging, since non-reducible oxides hardly lose their lattice oxygen (OL) or dissociate O2 from the gas phase. In this work, a ZnO monolayer film on Au(111) is used as an inverse catalyst to investigate CO oxidation occurring at the ZnO/Au(111) interface via high pressure scanning tunneling microscopy. Surface science experiments indicate that oxygen intercalation under the ZnO monolayer film, termed ZnO/O/Au(111), can be achieved via a surface reaction with 1 × 10-6 mbar O3. Subsequent exposure of the formed ZnO/O/Au(111) surface to mbar CO at room temperature leads to the recovery of the pristine ZnO/Au(111) surface. Theoretical calculations reveal that OL adjacent to intercalated oxygen (Oint) is activated due to the OL-Zn-Oint bonding and surface corrugation, which can be directly involved in CO oxidation. Subsequently, Oint migrates to the formed oxygen vacancy from the subsurface resuming the pristine ZnO structure. These results thus reveal that oxygen intercalation underneath single-layer ZnO will strongly boost the oxidation reaction via activating adjacent lattice oxygen atoms.

Direct observation of accelerating hydrogen spillover via surface-lattice-confinement effect.

Uncovering how hydrogen transfers and what factors control hydrogen conductivity on solid surface is essential for enhancing catalytic performance of H-involving reactions, which is however hampered due to the structural complexity of powder catalysts, in particular, for oxide catalysts. Here, we construct stripe-like MnO(001) and grid-like Mn3O4(001) monolayers on Pt(111) substrate and investigate hydrogen spillover atop. Atomic-scale visualization demonstrates that hydrogen species from Pt diffuse unidirectionally along the stripes on MnO(001), whereas it exhibits an isotropic pathway on Mn3O4(001). Dynamic surface imaging in H2 atmosphere reveals that hydrogen diffuses 4 times more rapidly on MnO than the case on Mn3O4, which is promoted by one-dimension surface-lattice-confinement effect. Theoretical calculations indicate that a uniform and medium O-O distance favors hydrogen diffusion while low-coordinate surface O atom inhibits it. Our work illustrates the surface-lattice-confinement effect of oxide catalysts on hydrogen spillover and provides a promising route to improve the hydrogen spillover efficiency.

Diagnostic value of dynamic 18F-FDG PET/CT imaging in non-small cell lung cancer and FDG hypermetabolic lymph nodes.

Background: We aimed to investigate the diagnostic value of dynamic 2-deoxy-2-[18F]-fluoro-D-glucose positron emission tomography-computed tomography in non-small cell lung cancer and fluoro-D-glucose hypermetabolic lymph nodes. Methods: Patients who made an active appointment for positron emission tomography-computed tomography were randomly enrolled by referring to previous imaging data and clinical information. Finally, 34 histopathologically confirmed non-small cell lung cancers (18 adenocarcinoma and 16 squamous cell carcinoma cases) were prospectively studied using dynamic and static 2-deoxy-2-[18F]-fluoro-D-glucose positron emission tomography-computed tomography imaging (the diagnostic study has not yet been registered on a clinical trial platform). In dynamic positron emission tomography images, a volume of interest, defined by the thoracic aorta, was selected for estimating the arterial input function. Patlak and irreversible two-tissue compartment model analyses were performed based on the pixel points to obtain first-order characteristic kinetic parameters for each lesion and hypermetabolic lymph node. The first-order characteristic kinetic parameters were obtained based on the basic data of dynamic positron emission tomography images in the corresponding model and the lesion delineation of region-of-interest based on computed tomography images, such as V_Median (the median gray intensity of V), k3_Entropy, VB_Entropy, K1_Uniformity, and ki_Uniformity. The first-order characteristic kinetic parameters were also modeled by logistic regression for the differential diagnosis of non-small cell lung cancer and hypermetabolic lymph nodes. Maximum and mean standard uptake values (SUVmax and SUVmean, respectively) were obtained from static positron emission tomography images. The diagnostic efficacy of the parameters was evaluated using the receiver operating characteristic curve and the DeLong test. Results: There was a significant difference in the V_Median values of adenocarcinoma and squamous cell carcinoma. The regression models for K1, k3, and V provided good predictions of adenocarcinoma and squamous cell carcinoma typology. Significant differences were observed in k3_Entropy, VB_Entropy, K1_Uniformity, and ki_Uniformity between benign and malignant lymph nodes. The regression model of Ki, VB, and k3 could make a good prediction for identifying benign and malignant lymph nodes. Conclusions: Dynamic 2-deoxy-2-[18F]-fluoro-D-glucose positron emission tomography-computed tomography imaging showed high diagnostic value in the staging of non-small cell lung cancer and fluoro-D-glucose hypermetabolic lymph nodes, and can be of great use in non-small cell lung cancer lymph node staging and surgical decision-making.

A study on aviation supply chain network controllability and control effect based on the topological structure.

The present paper focuses on the controllability of the aviation supply chain network and establishes the judgment criterion for structural controllability of the aviation supply chain network. We determine the control effect by applying the control input to different nodes in the aviation supply chain network. These control nodes include the core enterprises of the aviation supply chain network, the upstream suppliers, and the downstream distributors. It is observed that the control effect is better when the control input is applied to the upstream suppliers of the aviation supply chain network than to the core enterprises of the aviation supply chain network. It is also more desirable to apply the control input to the core enterprises than to the distributors. That is, the control effect is the weakest when the control input is applied to the distributors, whereas the effect is best on application of the control to the upstream suppliers in the supply chain (that is, by choosing the upstream suppliers as the controlled nodes in the aviation supply chain network).

In vivo preclinical PET/CT imaging of carbon-11-labeled aminoglycerol probe for the diagnosis of liver fibrosis.

OBJECTIVE: As an important membrane protein, aquaglyceroporin involves liver glycerol metabolism, which can be used to stage liver fibrosis. In this study, we synthesized a novel molecular probe carbon-11-labeled AR ([11C]AR) with aminoglycerol (AR), and evaluated its preclinical performance for liver fibrosis diagnosis by positron emission tomography/computed tomography (PET/CT) imaging in vivo. METHODS: We developed a fully automatic synthesis procedure for the preparation of [11C]AR by radiolabeling glycerol analogue precursor AR with carbon-11. The liver uptake kinetics of [11C]AR was investigated using a rat model by the PET/CT scanner. The dynamic PET/CT scans were performed between the control group (n = 5) and experimental group (n = 25), which was divided into three subgroups (S1, S2 + S3, S4) based on the stages of liver fibrosis. The regions of interest (ROIs) of 20 pixels were drawn in the liver area on the reconstructed images. One-way analysis of variance and independent sample t test were used to analyze the statistical difference of the maximum standardized uptake value (SUVmax) among the groups at series of scanning time points (20 s, 60 s, 90 s, 150 s, 5 min, 10 min, 20 min and 25 min). RESULTS: The fully automatic synthesis of [11C]AR was successfully achieved with high synthesis efficiency (above 50%). The uptake of [11C]AR in progressive liver fibrosis tissues was significantly lower than that in healthy livers at all the imaging time points (P < 0.05), especially at early time points (before 10 min p.i.). A cut-off SUVmax value (1.1) at 150 s p.i. was set for discrimination progressive fibrosis from healthy liver. More experimental and healthy rats were tested with this new threshold to evaluate fibrosis situation. The sensitivity of detecting progressive fibrosis with [11C]AR was 100% in the second cohort. CONCLUSION: We demonstrated a new carbon-11-radiolabeled aminoglycerol PET/CT imaging probe [11C]AR for liver fibrosis diagnosis and staging, which may allow potential assessment of liver fibrosis stages in a rapid and noninvasive method.

Effect of different segmentation algorithms on metabolic tumor volume measured on 18F-FDG PET/CT of cervical primary squamous cell carcinoma.

BACKGROUND AND PURPOSE: It is known that fluorine-18 fluorodeoxyglucose PET/computed tomography (CT) segmentation algorithms have an impact on the metabolic tumor volume (MTV). This leads to some uncertainties in PET/CT guidance of tumor radiotherapy. The aim of this study was to investigate the effect of segmentation algorithms on the PET/CT-based MTV and their correlations with the gross tumor volumes (GTVs) of cervical primary squamous cell carcinoma. MATERIALS AND METHODS: Fifty-five patients with International Federation of Gynecology and Obstetrics stage Ia∼IIb and histologically proven cervical squamous cell carcinoma were enrolled. A fluorine-18 fluorodeoxyglucose PET/CT scan was performed before definitive surgery. GTV was measured on surgical specimens. MTVs were estimated on PET/CT scans using different segmentation algorithms, including a fixed percentage of the maximum standardized uptake value (20∼60% SUVmax) threshold and iterative adaptive algorithm. We divided all patients into four different groups according to the SUVmax within target volume. The comparisons of absolute values and percentage differences between MTVs by segmentation and GTV were performed in different SUVmax subgroups. The optimal threshold percentage was determined from MTV20%∼MTV60%, and was correlated with SUVmax. The correlation of MTViterative adaptive with GTV was also investigated. RESULTS: MTV50% and MTV60% were similar to GTV in the SUVmax up to 5 (P>0.05). MTV30%∼MTV60% were similar to GTV (P>0.05) in the 50.05) in the 100.05) in the SUVmax of at least 15 group. MTViterative adaptive was similar to GTV in both total and different SUVmax groups (P>0.05). Significant differences were observed among the fixed percentage method and the optimal threshold percentage was inversely correlated with SUVmax. The iterative adaptive segmentation algorithm led to the highest accuracy (6.66±50.83%). A significantly positive correlation was also observed between MTViterative adaptive and GTV (Pearson's correlation r=0.87, P<0.0001). CONCLUSION: MTViterative adaptive is independent of SUVmax, more accurate, and correlated with GTV. Iterative adaptive algorithm segmentation may be more suitable than the fixed percentage threshold method to estimate the tumor volume of cervical primary squamous cell carcinoma.

99mTc-3PRGD2 scintigraphy to stage liver fibrosis and evaluate reversal after fibrotic stimulus withdrawn.

OBJECTIVE: Scintigraphy using 99mTc-3PRGD2 targeting integrin αvß3 could assess activation of hepatic stellate cells (HSCs). Liver fibrogenesis is intimately associated with activation of HSCs, and the fibrolytic process is accompanied by the reduction of the activated HSCs. In this study, we aimed to evaluate the feasibility of this method to assess the severity of liver fibrosis and the reversal after the fibrotic stimulus withdrawal. METHODS: Liver fibrosis of different stages was induced by thioacetamide (TAA) injection for 2, 4 and 6 weeks (n = 6 for each time point). Another 6 rats with 8-week TAA administration (the 8-week group) and 6 rats which were injected with TAA for 6 weeks, and then withdrawn of TAA for 2 weeks (spontaneous recovery rats, SRR) were designed. The ratios of radioactivity detected in the liver vs. the heart at 30 min post-injection of 99mTc-3PRGD2 (L/H30min), the collagen proportionate area (CPA), the protein and mRNA levels of integrin αv, integrin ß3 were analyzed and compared among groups. RESULTS: The Ishak stage scores of the livers in the control and 2, 4, 6-week groups increased when the TAA administration period was extended. L/H30min increased with the upgrading of liver fibrosis and the differences between each pair of groups were statistically significant (p 30 min in the 8-week group was similar to that in the 6-week group (p > 0.05), but was significantly higher than that in the SRR group (p = 0.005). CONCLUSIONS: Scintigraphy using 99mTc-3PRGD2 may provide a non-invasive method for grading liver fibrosis and assessing liver fibrosis reversal.

PET/MRI with diagnostic MR sequences vs PET/CT in the detection of abdominal and pelvic cancer.

OBJECTIVE: Integrated positron emission tomography/magnetic resonance imaging (PET/MRI) scanners provide combined MR-based anatomic and metabolic image information. The aim of this study was to evaluate qualitative and quantitative diagnostic performance of PET/MR with (18)fluoro-2-deoxyglucose ((18)F-FDG) using a diagnostic MR sequence in patients with abdominal and pelvic tumors, compared to positron emission tomography/computed tomography (PET/CT). MATERIALS AND METHODS: Forty five patients underwent a single-injection ((18)F-FDG), dual-imaging protocol including whole-body PET/CT and subsequent regional PET/MR hybrid imaging. A regional PET/MR scan followed the PET/CT. Images from both modalities were analyzed using a 3-point scale for PET/CT and PET/MR image quality, image alignment, and lesion visibility on PET images. PET-CT/PET-MR functional and anatomical correlation was analyzed. RESULTS: A total of 66 lesions were studied, from which 63 were identified using PET/CT and 59 were identified using PET/MR. The (18)F-FDG PET images had good diagnostic quality (P<0.001); alignment was found to be excellent in PET/MR data as well as PET/CT data (P=0.102), and there was no difference in lesion visibility (P=0.18). The average rating score regarding anatomical correlation for PET-positive lesions was 2.75 for combined MR sequence images and 2.04 for CT, with a significant difference (P=0.317), Standard uptake value (SUV) for focal lesions had excellent correlation (SUVmax/mean: R=0.948/0.948); furthermore, the SUVmean of background organs combined, bone marrow and the muscle tissue showed good correlation (R=0.329/0.398/0.298). No correlations were found in the liver and spleen. CONCLUSIONS: PET/MR with diagnostic MR sequence was able to detect abdominal and pelvic lesions and had good image quality compared to PET/CT. SUVmax and SUVmean values in focal lesions, and the SUVmean of background organs generally correlated well in abdominal and pelvic oncology patients examined using PET/CT and PET/MRI.

Assessing activation of hepatic stellate cells by (99m)Tc-3PRGD2 scintigraphy targeting integrin αvß3: a feasibility study.

OBJECTIVE: Hepatic stellate cell (HSC) activation, which is accompanied by increased expression of integrin αvß3, is an important factor in liver fibrogenesis. Molecular imaging targeting the integrin αvß3 could provide a non-invasive method for evaluating the expression and the function of the integrin αvß3 on the activated HSCs (aHSCs) in the injured liver, and then provide important prognostic information. (99m)Tc-3PRGD2 is such a radiotracer specific for integrin αvß3. In this study, we aimed to compare the differences in liver uptake and retention of the (99m)Tc-3PRGD2 between normal liver and injured liver to evaluate the feasibility of (99m)Tc-3PRGD2 scintigraphy for this purpose. METHODS: We used planar scintigraphy to assess changes in integrin αvß3 binding of intravenously-administered (99m)Tc-3PRGD2 in the livers of rats with thioacetamide (TAA)-induced liver fibrosis compared with the controls. We co-injected cold c(RGDyK) with (99m)Tc-3PRGD2 to assess the specific binding of the radiotracer. We performed Sirius red staining to assess liver fibrosis, immunofluorescent colocalization to identify the location of integrin αvß3 expressed in the fibrotic liver, and we measured protein and messenger RNA expression of integrin αvß3 and alpha smooth muscle actin (α-SMA) in the control and fibrotic livers. RESULTS: The fibrotic livers showed enhanced (99m)Tc-3PRGD2 uptake and retention. The radiotracer was demonstrated to bind specifically with the integrin αvß3 mainly expressed on the aHSCs. The liver-to-heart ratio at 30 min post-injection was higher in the fibrotic livers than in the control livers (TAA, 1.98±0.08 vs. control, 1.50±0.12, p<0.01). The liver t1/2 was longer than in the controls (TAA, 27.07±10.69 min vs. control, 12.67±4.10 min, p<0.01). The difference of heart t1/2 between the two groups was not statistically significant (TAA, 3.13±0.63 min vs. control, 3.41±0.77 min, p=0.94). CONCLUSIONS: (99m)Tc-3PRGD2 molecular imaging can provide a non-invasive method for assessing activation of HSCs.

Calibration-free gaze tracking for automatic measurement of visual acuity in human infants.

Most existing vision-based methods for gaze tracking need a tedious calibration process. In this process, subjects are required to fixate on a specific point or several specific points in space. However, it is hard to cooperate, especially for children and human infants. In this paper, a new calibration-free gaze tracking system and method is presented for automatic measurement of visual acuity in human infants. As far as I know, it is the first time to apply the vision-based gaze tracking in the measurement of visual acuity. Firstly, a polynomial of pupil center-cornea reflections (PCCR) vector is presented to be used as the gaze feature. Then, Gaussian mixture models (GMM) is employed for gaze behavior classification, which is trained offline using labeled data from subjects with healthy eyes. Experimental results on several subjects show that the proposed method is accurate, robust and sufficient for the application of measurement of visual acuity in human infants.

Value of ¹8F-FDG PET/CT in the diagnosis of primary gastric cancer via stomach distension.

OBJECTIVE: To clarify the usefulness of (18)F-FDG PET/CT for detecting primary gastric cancer via gastric distention using a mixture of milk and Diatrizoate Meglumine. MATERIALS AND METHODS: A total of 68 patients (male: 47, female: 21; age: 41-87 years) suspected of gastric carcinoma underwent (18)F-FDG PET/CT imaging. After whole-body PET/CT imaging in a fasting state, the patients drank a measured amount of milk with Diatrizoate Meglumine. Local gastric district PET/CT imaging was performed 30 min later. The imaging was analyzed by semi-quantitative analysis, standardized uptake value (SUV) of the primary tumor was measured in a region of interest. The diagnosis results were confirmed by gastroscopy, pathology, and follow-up results. RESULTS: Of the 68 patients, 56 malignant gastric neoplasm patients (male: 37, female: 19) were conformed. The sensitivity, specificity, positive predictive value and negative predictive value of fasting whole-body PET/CT imaging for a primary malignant tumor were 92.9%, 75.0%, 94.5%, and 69.0%, respectively. The values for distension with a mixture of milk and Diatrizoate Meglumine were 91.1%, 91.7%, 98.1%, and 68.8%, respectively. The area under the curve was 0.919 ± 0.033 and 0.883 ± 0.066 for the diagnosis of gastric cancer with SUVmax in a fasting state and after intake of mixture respectively, the differences were not statistically significant (P=0.359). Using gastric distension with a mixture of milk and Diatrizoate Meglumine, the mean ratio of the lesion's SUVmax to the adjacent gastric wall SUVmax increased significantly from 3.30 ± 3.05 to 13.50 ± 15.05, which was statistically significant (P<0.001). CONCLUSIONS: (18)F-FDG PET/CT imaging is highly accurate for the diagnosis of primary gastric carcinoma. Gastric distention can display the lesions more clearly, however, it cannot significantly improve diagnostic accuracy.