Maximum likelihood synchronization algorithm correction for photon-counting communications with blocking loss.

To realize deep space optical communications with high capacity and sensitivity, synchronization of pulse-position modulation (PPM) signals is crucial. In this study, the maximum likelihood synchronization algorithm based on inter-symbol guard times was generalized to the scenario with strong blockage of single-photon detectors, where higher PPM slot frequency and signal-noise ratio could be adopted. Furthermore, a slot frequency offset compensation method was proposed, and simulations and experiments were performed to verify the performance improvement of the proposed corrected synchronization algorithm under blockage. The results indicated that the deadtime-corrected synchronization scheme could effectively overcome the performance degradation of the original model under high photon flux, provide estimation (0.02749 slots @ root-mean-square error) close to the Cramér-Rao Bound, and error rates close to ideal synchronization in the experiment.

Regulating oxygen vacancies and hydroxyl groups of α-MnO2 nanorods for enhancing post-plasma catalytic removal of toluene.

Although nonthermal plasma (NTP) technology has high removal efficiency for volatile organic compounds (VOCs), it has limited carbon dioxide (CO2) selectivity, which hinders its practical application. In this study, α-MnO2 nanorods with tunable oxygen vacancies and hydroxyl groups were synthesized by two-step hydrothermal process to enhance their activity for deep oxidation of toluene. Hydrochloric acid (HCl) was used to assist in synthesis of α-MnO2 nanorods with tunable oxygen vacancies, furtherly, more hydroxyl groups were introduced to HCl-assisted synthesized α-MnO2 by K+ supplement. The results showed that the as-synthesized nanorods exhibited superior activity, improved by nearly 30% removal efficiency of toluene compared to pristine MnO2 at SIE = 339 J/L, and reaching high COx selectivity of 72% at SIE = 483 J/L, successfully promoting the deep oxidation of toluene. It was affirmed that oxygen vacancies played an important role in toluene conversion, improving the conversion of ozone (O3) and resulting in higher mobility of surface lattice oxygen species. Besides, the enhancement of deep oxidation performance was caused by the increase of hydroxyl groups concentration. In-situ DRIFTS experiments revealed that the adsorbed toluene on catalyst surface was oxidized to benzyl alcohol by surface lattice oxygen, and hydroxyl groups were also found participating in toluene adsorption. Overall, this study provides a new approach to designing catalysts for deep oxidation of VOCs.

PicassoNet: Searching Adaptive Architecture for Efficient Facial Landmark Localization.

Since recent facial landmark localization methods achieve satisfying accuracy, few of them enable fast inference speed, which, however, is critical in many real-world facial applications. Existing methods typically employ complicated network structure and predict all the key points through uniform computation, which is inefficient since individual facial part might take different computation to obtain the best performance. Taking both accuracy and efficiency into consideration, we propose the PicassoNet, a lightweight cascaded facial landmark detector with adaptive computation for individual facial part. Different from the conventional cascaded methods, PicassoNet integrates refinement submodules into a single network with group convolution, where each convolution group predicts landmarks from an individual facial part. Note that the groups' structures are flexible in the training process. Then, a novel grouping search algorithm is proposed to optimize the group division. With formulating the optimization as a network architecture search (NAS) problem, the grouping search adaptively allocates computation to each group and obtains an efficient structure. In addition, we propose a boundary-aware loss to optimize along tangent and normal of facial boundaries, instead of optimizing along horizontal and vertical as the conventional loss (L2, SmoothL1, WingLoss, and so on) do. The novel loss improves the joint locations of predicted keypoints. Experiments on three benchmark datasets AFLW, 300W, and WFLW show that the proposed method runs over 6× times faster than the state of the arts and meanwhile achieves comparable accuracy.

Insights into the influence of water molecules on selective catalytic ozonation of gaseous ammonia into nitrogen on cryptomelane-type manganese oxide using in-situ DRIFTS.

Catalytic ozonation is an environmentally friendly technology for the removal of gaseous NH3 due to high NH3 conversion and high N2 selectivity at ambient temperature. However, the influence mechanism of ubiquitous water vapor on catalytic ozonation of NH3 is unclear. In this study, cryptomelane-type manganese oxide (OMS-2) catalyst was prepared and tested for catalytic ozonation of NH3 in different relative humidity. The results showed that water vapor significantly decreased the catalytic activity, which was due to the inhibition of water on NH3 adsorption on Lewis acid sites and O3 decomposition on oxygen vacancies, as well as the combination of water with active oxygen species (O22- and Oatom). And the effect of water vapor on NH3 conversion was more significant than O3 decomposition because more Mn-OH were involved in the O3 decomposition under humid conditions. Combining in-situ DRIFTS results with the performance of NH3 oxidation, it is found that L-2 acid sites (the peak of NH3 adsorption on Lewis acid sites at 1188 cm-1) were the main active sites for adsorption and activation of NH3 in the early stage of catalytic reaction; as the reaction progressed, L-2 acid sites were gradually occupied by water and more Brønsted acid sites participated in the catalytic reaction. This work deepened the understanding of the reaction process for selective catalytic ozonation of NH3, and provided theoretical guidance for the design of efficient hydrophobic catalysts to eliminate gaseous NH3 pollution.

Tuning the Micro-coordination Environment of Al in Dealumination Y Zeolite to Enhance Electron Transfer at the Cu-Mn Oxides Interface for Highly Efficient Catalytic Ozonation of Toluene at Low Temperatures.

The development of stable, highly active, and inexpensive catalysts for the ozone catalytic oxidation of volatile organic compounds (VOCs) is challenging but of great significance. Herein, the micro-coordination environment of Al in commercial Y zeolite was regulated by a specific dealumination method and then the dealuminated Y zeolite was used as the support of Cu-Mn oxides. The optimized catalyst Cu-Mn/DY exhibited excellent performance with around 95% of toluene removal at 30 °C. Besides, the catalyst delivered satisfactory stability in both high-humidity conditions and long-term reactions, which is attributed to more active oxygen vacancies and acidic sites, especially the strong Lewis acid sites newly formed in the catalyst. The decrease in the electron cloud density around aluminum species enhanced electron transfer at the interface between Cu-Mn oxides. Moreover, extra-framework octahedrally coordinated Al in the support promoted the electronic metal-support interaction (EMSI). Compared with single Mn catalysts, the incorporation of the Cu component changed the degradation pathway of toluene. Benzoic acid, as the intermediate of toluene oxidation, can directly ring-open on Cu-doped catalysts rather than being further oxidized to other byproducts, which increased the rate of the catalytic reaction. This work provides a new insight and theoretical guidance into the rational design of efficient catalysts for the catalytic ozonation of VOCs.

Mesoporous poorly crystalline α-Fe2O3 with abundant oxygen vacancies and acid sites for ozone decomposition.

In this work, mesoporous poorly crystalline hematite (α-Fe2O3) was prepared using mesoporous silica (KIT-6) functionalized with 3-[(2-aminoethyl)amino]propyltrimethoxysilane as a hard template (SMPC-α-Fe2O3). The disordered atomic arrangement structure of SMPC-α-Fe2O3 promoted the formation of oxygen vacancies, which was confirmed using X-ray photoelectron spectroscopy (XPS), O2-temperature-programmed desorption (TPD), H2-temperature-programmed reduction (TPR), and in situ diffuse reflectance infrared Fourier transform (DRIFT) analyses. Density functional theory calculations (DFT) also proved that reducing the crystallinity of α-Fe2O3 decreased the formation energy of oxygen vacancies. TPD and in situ DRIFT analyses of NH3 adsorption suggested that the surface acidity of SMPC-α-Fe2O3 was considerably higher than those of mesoporous poorly crystalline α-Fe2O3 (MPC-α-Fe2O3) and highly crystalline α-Fe2O3 (HC-α-Fe2O3). The oxygen vacancies and acid sites formed on α-Fe2O3 surface are beneficial for ozone (O3) decomposition. Compared with MPC-α-Fe2O3 and HC-α-Fe2O3, SMPC-α-Fe2O3 exhibited a higher removal efficiency for 200-ppm O3 at a space velocity of 720 L g-1 h-1 at 25 ± 2 °C under dry conditions. Additionally, in situ DRIFT and XPS results suggested that the accumulation of peroxide (O22-) and the conversion of O22- to lattice oxygen over the oxygen vacancies caused catalyst deactivation. However, O22- could be desorbed completely by continuous N2 purging at approximately 350 °C. This study provides significant insights for developing highly active α-Fe2O3 catalysts for O3 decomposition.

Efficacy and safety of Brucea javanica oil emulsion for liver cancer: A protocol for systematic review and meta-analysis.

BACKGROUND: Brucea javanica oil emulsion (BJOE), extracted from the Chinese herb Bruceae Fructus (Yadanzi), is a broad-spectrum anti-tumor drug and has been widely used for the treatment of liver cancer in China. The aim of this study is to systematically investigate the efficacy and safety of BJOE for the treatment of liver cancer. METHODS: Seven electronic databases including the Cochrane Library, PubMed, Excerpt Medica Database, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, China Scientific Journal Database, and Wanfang Database will be systematically retrieved for data extraction from their inceptions to September 2020. Cochrane Risk of Bias tool will be used to assess the risk of bias of included studies. The RevMan 5.4 and Stata 16.0 software will be applied for statistical analyses. Statistical heterogeneity will be computed by I tests. Sensitivity analysis will be conducted to evaluate the stability of the results. The publication bias will be evaluated by funnel plots and Egger test. The quality of evidence will be assessed by the GRADE system. RESULTS: The results of our research will be published in a peer-reviewed journal or presenting the findings at a relevant conference. CONCLUSION: The conclusion of this study will provide helpful evidence of the effect and safety of BJOE for the treatment of liver cancer in clinical practice. OSF REGISTRATION NUMBER: 10.17605/OSF.IO/UC8XQ.

Pre-ozonation for the mitigation of reverse osmosis (RO) membrane fouling by biopolymer: The roles of Ca2+ and Mg2.

Despite plenty of literatures focused on the application of pre-ozonation prior to membrane, it was still unclear about the role of divalent cations (Ca2+ and Mg2+) in reverse osmosis (RO) membrane fouling mitigation. In this study, ozone pre-treatment (0.10, 0.25 and 0.50 mg O3/mg DOC (dissolved organic carbon)) was employed to oxidize model biopolymer, which was represented by bovine serum albumin (BSA) and sodium alginate (SA) in the presence of Ca2+ and Mg2+ (0.5, 1.0 and 2.0 mM). Cross-flow filtration was conducted to investigate RO membrane fouling by concentration mode. The results showed that at appropriate ozone dose there were measurable changes in physicochemical properties of BSA and SA, including increases in particle size, hydrophilicity, density of negative charge and carboxylic groups. Pre-ozonation markedly alleviated RO fouling by BSA at ozone dose of 0.25 mg O3/mg DOC when Ca2+ and Mg2+ concentrations raised from 0.5 to 2.0 mM since the increase in electrostatic (EL) repulsion and decrease in hydrophobic (HP) interaction compensated the increase in divalent cation bridging. Similar results were obtained for SA fouling in the presence of Mg2+. In contrast, the effect of pre-ozonation on SA fouling strongly depended on the concentration of Ca2+. In brief, it mitigated SA fouling at 0.5 mM Ca2+, whereas accelerated irreversible fouling at higher Ca2+ concentration (1.0 and 2.0 mM) due to the overwhelming effect of divalent cation bridging compared to EL and HP interactions, as revealed by adsorption experiments (in-situ streaming potential measurement). Pre-ozonation shifted the fouling layer from compact to porous and weakened the adhesion forces between foulants and membrane (foulants) except for SA containing 1.0 and 2.0 mM Ca2+. This study may provide the guidance for the application of pre-ozonation prior to RO filtration.