Identification of Alkoxy Radicals as Hydrogen Atom Transfer Agents in Ce-Catalyzed C-H Functionalization.

The intermediacy of alkoxy radicals in cerium-catalyzed C-H functionalization via H-atom abstraction has been unambiguously confirmed. Catalytically relevant Ce(IV)-alkoxide complexes have been synthesized and characterized by X-ray diffraction. Operando electron paramagnetic resonance and transient absorption spectroscopy experiments on isolated pentachloro Ce(IV) alkoxides identified alkoxy radicals as the sole heteroatom-centered radical species generated via ligand-to-metal charge transfer (LMCT) excitation. Alkoxy-radical-mediated hydrogen atom transfer (HAT) has been verified via kinetic analysis, density functional theory (DFT) calculations, and reactions under strictly chloride-free conditions. These experimental findings unambiguously establish the critical role of alkoxy radicals in Ce-LMCT catalysis and definitively preclude the involvement of chlorine radical. This study has also reinforced the necessity of a high relative ratio of alcohol vs Ce for the selective alkoxy-radical-mediated HAT, as seemingly trivial changes in the relative ratio of alcohol vs Ce can lead to drastically different mechanistic pathways. Importantly, the previously proposed chlorine radical-alcohol complex, postulated to explain alkoxy-radical-enabled selectivities in this system, has been examined under scrutiny and ruled out by regioselectivity studies, transient absorption experiments, and high-level calculations. Moreover, the peculiar selectivity of alkoxy radical generation in the LMCT homolysis of Ce(IV) heteroleptic complexes has been analyzed and back-electron transfer (BET) may have regulated the efficiency and selectivity for the formation of ligand-centered radicals.

Photocatalytic Aerobic Oxidative Ring Expansion of Cyclic Ketones to Macrolactones by Cerium and Cyanoanthracene Catalysis.

We describe a cerium-catalyzed aerobic oxidative ring expansion for the expedient construction of synthetically challenging macrolactones under visible-light conditions. Cyanoanthracene has been employed as co-catalyst to accelerate the turnover of the cerium cycle leading to a fast conversion within 20 min of irradiation. Taking advantage of the high efficiency and operationally simple conditions, a collection of over 100 macrolactones equipped with ring systems ranging from 9- to 19-membered macrocycles have been prepared from simple building blocks. Moreover, the enabling potential of this strategy to simplify the generation of molecular complexity has been demonstrated through the concise synthesis of sonnerlactone.

Image processing for GEO object with 3D rotation based on ground-based InISAL with orthogonal baselines.

While imaging geosynchronously orbiting objects with ground-based inverse synthetic aperture LADAR (ISAL), target rotation and vibration will introduce phase errors into the echo and cause the two-dimensional imaging result to be defocused. To solve this problem, one layout of the ISAL receiving channels is designed, combining the orthogonal short baselines in the inner field with the orthogonal long baselines in the external field. On this basis, an imaging method based on orthogonal interferometry processing is proposed. The proposed method estimates and compensates for the phase errors introduced by the rotation and vibration of the target such that the focus of the two-dimensional image is improved, and three-dimensional imaging results with high accuracy are obtained. The effectiveness of the proposed method is verified by simulation data.

Interleukin-1 receptor antagonist inhibits angiogenesis in gastric cancer.

BACKGROUND: Interleukin-1 alpha (IL-1α) plays an important role in tumorigenesis and angiogenesis of gastric cancer. The interleukin-1 receptor antagonist (IL-1RA) inhibits IL-1 selectively and specifically through IL-1R type I (IL-1RI). However, the underlying mechanism by which IL-1RA modulates the interactions of tumor cells and their micro-environment is poorly understood. We have evaluated the role of IL-1RA in the metastatic process as well as the mutual or reciprocal actions between gastric cancer cells and stromal cells. MATERIALS AND METHODS: The expressions of IL-1α, vascular endothelial growth factor (VEGF), and IL-1RI mRNA were determined by reverse transcriptase-PCR. The regulatory effect of IL-1RA on the secretion of VEGF in human gastric cancer cells and human umbilical vein endothelial cells (HUVECs) was detected by enzyme-linked immunosorbent assay. The effect of IL-1RA on metastatic potential was evaluated using proliferation, invasion, and angiogenesis assays, respectively, including in vitro co-culture system models consisting of tumor cells and stromal cells that were used to detect invasion and angiogenesis. RESULTS: Interleukin-1α mRNA was detected in the higher liver metastatic gastric cell line MKN45. IL-1α protein was expressed in MKN45 cells and in HUVECs. VEGF mRNA and protein were detected in the three gastric cancer cell lines (MKN4, NUGC-4, and AGS). Levels of VEGF secreted by gastric cancer cells and HUVECs appeared to be reduced through the action of IL-1RA via IL-1RI in a dose-dependent manner (P < 0.01). IL-1RA significantly inhibited the proliferation and migration of HUVECs (P < 0.01) and tube formation by HUVECs (P < 0.01), both in a dose-dependent manner. Compared with HUVECs grown without cancer cells (control) or with NUGC-4 cells, tube formation by HUVECs was significantly enhanced by co-culture with MKN45 cells (P < 0.01). The enhanced tube formation in the presence of MKN45 cells was inhibited by the addition of IL-1RA (P < 0.01). CONCLUSIONS: The IL-1RA downregulated the metastatic potential of gastric cancer through blockage of the IL-1α/VEGF signaling pathways. IL-1RA has the potential to play a role in the treatment of gastric cancer.

Interferometric inverse synthetic aperture ladar target detection method.

To improve the target detection performance of inverse synthetic aperture ladar (ISAL) under the situation that there is Doppler bandwidth ambiguity, we consider energy accumulation of echo signals along a range through matched illumination. However, since the target impulse responses change with the target aspect angle, the phase shifts along slow-time between range cells are different, and the output of matched illumination fluctuates along slow-time. To reduce the slow-time fluctuation of matched illumination under additive white Gaussian noise assumption, we have proposed an interferometric ISAL (InISAL) target detection method based on interferometry processing and principal component analysis (PCA) in this paper. After the interferometry processing, the interferometric phase shifts along slow-time of all range cells are approximately the same. Then PCA is introduced to reduce the impact of noise, interference, and cross-terms of interferometry processing. Thus, the slow-time fluctuation of matched illumination can be decreased, and the target detection performance is improved. The proposed method has been validated with both simulated data of InISAL and real data of millimeter-wave interferometric synthetic aperture radar.

Fracture Conductivity Prediction Based on Machine Learning.

Hydraulic fracturing technology is the main method to develop low-permeability reservoirs. Fracture conductivity is not only the basis of fracture optimization design but also one of the key parameters to determine the effect of hydraulic fracturing. However, current methods of calculating fracture conductivity require a lot of time and labor cost. This research proposes a fracture conductivity prediction model based on machine learning. The main controlling factors of fracture conductivity are determined using the Pearson coefficient method and gray correlation analysis. Example application shows that the R2 values of the BP neural network model based on a genetic algorithm for predicting the fracture conductivity of block A and block B are 0.981 and 0.975, respectively, indicating that the machine learning model can accurately predict fracture conductivity.

Obstructive sleep apnea and cardiovascular events in acute coronary syndrome: a meta-analysis.

OBJECTIVE: Obstructive sleep apnea (OSA) in patients with the acute coronary syndrome (ACS) were at high risk for cardiovascular events, but the results are currently inconclusive. We aimed to conduct a systematic review to determine the incidence of cardiovascular events among ACS patients with OSA by a meta-analysis of observational studies. METHODS: PubMed, Embase, and Cochrane Library were searched for studies related to the association between OSA and the risk of cardiovascular events in patients with ACS. Risk of bias in observational studies was assessed according to the Risk Of Bias In the Non-randomized Studies-Of Interventions tool.We performed a meta-analysis using a random-effects model to calculate estimates of pooled hazard ratios (HR) with 95% confidence intervals (CI), and heterogeneity was assessed using the statistics. RESULTS: A total of 12 studies evaluating ACS patients with OSA were included in the meta-analysis. OSA was related to the increased risk of MACE (HR = 2.2; 95% CI, 1.274-3.805, I2 = 76.1%). The effect of OSA on MACCE (HR = 1.921; 95% CI, 1.45-2.546; I2 = 19.1%) and readmission for unstable angina (HR = 3.137, 95% CI, 1.06-9.283; I2 = 52.4%) were statistically significant in the pooled analysis. All of the outcomes in the included studies had a serious risk of bias and the Grading of Recommendation, Assessment, Development, and Evaluation evidence level of all the evaluation results were very low. CONCLUSIONS: OSA was associated with a significant increase in the risk of cardiovascular events for patients with ACS. Additional randomized controlled trial studies are required to confirm the results and to prove the treatment of OSA can change the prognosis.

The quantification and assessment of depression and anxiety in patients with postoperative gastroparesis syndrome.

BACKGROUND: This study aimed to analyze the stage-situation depression and anxiety as well as independent influential factors in patients with postsurgical gastroparesis syndrome (PGS) and to provide dependent indications for treatment. PATIENTS AND METHODS: The self-rating depression scale (SDS) and self-rating anxiety scale (SAS) were used to test the depression and anxiety of 53 patients with PGS, who were treated in the Department of Gastroenterological Surgery of Gansu Provincial Hospital from January 2012 to October 2016. A comparison between the SDS or SAS scores of patients with PGS and without PGS was undertaken; then, we retrospectively analyzed the factors influencing depression and anxiety in PGS patients. RESULTS: The patients with PGS' mean scores of depression and anxiety were 49.92±11.37 and 50.91±6.57, respectively, which were higher than that of patients without PGS in the Chinese population (P<0.05). The results of multivariate logistic regression analysis indicated that the independent influential factors of depression and anxiety in patients with PGS included course of disease, pancreatic juice leakage, preoperative outflow tract obstruction, postoperative abdominal infection, and anastomotic complication (P<0.05). Patients with a disease course longer than 30 days; with pancreatic juice leakage; and who suffered from preoperative outflow tract obstruction, postoperative abdominal infection, and anastomotic complication had higher ratios of depression and anxiety. CONCLUSION: Depression and anxiety are clearly evident in patients with PGS, and we should pay attention to this phenomenon and provide appropriate treatment.