Knowledge-based adaptive polarimetric detection in heterogeneous clutter

The detection performance and the constant false alarm rate behavior of the conventional adaptive detectors are severely degraded in heterogeneous clutter. This paper designs and analyses a knowledge-based （KB） adaptive polarimetric detector in het-erogeneous clutter. The proposed detection scheme is composed of a data selector using polarization knowledge and an adaptive polarization detector using training data. A polarization data selector based on the maximum likelihood estimation is proposed to remove outliers from the heterogeneous training data. This selector can remove outliers effectively, thus the training data is purified for estimating the clutter covariance matrix. Consequently, the performance of the adaptive detector is improved. We assess the performance of the KB adaptive polarimetric detector and the adaptive polarimetric detector without a data selector using simulated data and IPIX radar data. The results show that the KB adaptive polarization detector outperforms its non-KB counterparts.

The Mechanism of Lipofectamine 2000 Mediated Transmembrane Gene Delivery

In this paper, the relatived mechanism between lipofectamine 2000 mediated transmembrane gene delivery and endocytic pathway were investigated. Clathrin and caveolae-mediated endocytic pathway contributions to transfection efficiency were studied. The inhibitors of endocytosis were used to treat HEp-2 cells before lipofectamine 2000/pGFP-N2 transfection. Transfection efficiency was evaluated with green fluorescence protein (GFP) expression assays. Cell viability and cytotoxicity were evaluated with MTT method. The results indicated that inhibitors of clathrin (chlorpromazine or wortmannin) and caveolin (genistein) could reduce the cell transfection efficiency observably. Both clathrin and caveolae-mediated endocytic pathways play important roles in transmembrane gene delivery.

In Vitro Study of Carbamate-Linked Cationic Lipid for Gene Delivery Against Cervical Cancer Cells

Design and synthesis of a carbamate-linked cationic lipid DDCTMA (N-[1-(2,3-didodecylcarbamoyloxy)propyl]-N,N,N-trimethylammonium iodide)? as gene delivery carriers was described in this work. The transfection efficiency of cationic liposome increased dramatically with the increase in the content of DOPE. In addition, the transfection efficiency of some of cationic lipoplexes was superior or parallel to that of two commercial transfection agents, Lipofectamine2000 and DOTAP. The carbamate-linked cationic lipid DDCTMA/DOPE may be a promising gene carrier that has high transfection efficiency as well as low cytotoxicity.

O-Alkylation of Chitosan for Gene Delivery by Using Ionic Liquid in an in- situ Reactor

An in-situ reactor was elaborately designed for O-alkylation of chitosan in an ionic liquid ([BMIM]Cl) solvent, using N, N'-carbonyldiimidazole? as bonding agent. The original chitosan and the modified chitosan were characterized by FT-IR and XRD analysis. FT-IR spectra revealed that the alkylation of chitosan selectively occurred at hydroxyl groups, with unprotected amino groups untouched. It was proposed that the particular properties of the ionic liquid solvent should be responsible for the selectively alkylation. The result from X-ray diffraction showed that the crystallinity of O-alkylation of chitosan decreases, most likely due to the decomposition of CS in the ionic liquid. The solubility test of O-alkylated chitosan in aqueous HAc solution (w/w: 0.1%) confirmed that the product could be easily dissolved in aqueous HAc solution because of its abundant free amino groups. It was suggested that the O-alkylated chitosan was suitable for the coming cell transfection test in vitro.

A Novel Method for the Protection and Activation of Histidine

The yield and purity of synthetic peptides were greatly related to the amino acid protection and activation during the synthesis process. Therefore, the amino acid protection and activation are the most important steps in peptide synthesis. By using tetrahydrofuran as the solvent, 9-fluorenylmethoxycarbonyl as protection group, 2-(7-azobenzotri- azol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (HATU) as condensation reagent an amino protected histidine ester was given. In this article a novel synthesis method for N-(9- fluorenylmethoxycarbonyl)-histidine active ester was established. The reaction conditions for preparing this active ester were optimized. The experimental results indicated that solvents and active reagents had remarkable effects on the yield of active ester. The best conditions for preparing the active ester was a ratio of n (Fmoc-His-OH): n (HATU) = 1:1.2 with THF used as the solvent at room temperature. The yield of the final product was about 80% with a purity of over 85%. This simple method would provide fundamentals for the synthesis of other protected amino acid active esters.

Low-temperature selective synthesis of metastableα-MoC with electrochemical properties:Electrochemical co-reduction of CO_(2)and MoO_(3)in molten salts

Metastable molybdenum carbide(α-MoC),as a catalyst and an excellent support for metal catalysts,has been widely used in thermo/electro-catalytic reactions.However,the selective synthesis ofα-MoC remains a great challenge.Herein,a simple one-pot synthetic strategy for the selective preparation of metastableα-MoC is proposed by electrochemical co-reduction of CO_(2)and MoO_(3)in a low-temperature eutectic molten carbonate.The synthesizedα-MoC shows a reed flower-like morphology.By controlling the electrolysis time and monitoring the phase and morphology of the obtained products,the growth process ofα-MoC is revealed,where the carbon matrix is deposited first followed by the growth ofα-MoC from the carbon matrix.Moreover,by analyzing the composition of the electrolytic products,the formation mechanism forα-MoC is proposed.In addition,through this one-pot synthetic strategy,S-dopedα-MoC is successfully synthesized.Density functional theory(DFT)calculations reveal that S doping enhanced the HER performance ofα-MoC by facilitating water absorption and dissociation and weakening the bond energy of Mo-H to accelerate H desorption.The present work not only highlights the valuable utilization of CO_(2) but also offers a new perspective on the design and controllable synthesis of metal carbides and their derivatives.

Transformation of postsynthesized F-MOF to Fe/N/F-tridoped carbon nanotubes as oxygen reduction catalysts for high power density Zn-air batteries

The oxygen reduction reaction(ORR),an important process in Zn-air batteries(ZABs),shows sluggish reaction kinetics,which significantly impairs the further improvement of battery performance.Thus,rationally designing cathodic catalysts for ZABs has drawn sufficient attention.We herein synthesize and characterize Fe/N/F-tridoped CNTs(FeNFCs)by annealing the postsynthesized trifluoroacetic anhydridemodified Fe-MIL-88B-NH_(2)nanocrystals with melamine at high temperature in a N_(2)atmosphere.Benefiting from the Fe/N/F element doping,high specific surface area,and CNT structure,the FeNFC800 catalyst prepared at 800℃exhibits a preferable half-wave potential of 0.829 V vs.RHE.The Zn-air battery equipped with Fe NFC800 shows a high open-circuit voltage of 1.47 V,a gratifying peak power density of196 mW/cm^(2),and extraordinary long-term stability,outperforming the benchmark 20%Pt/C.

Deletion of Gab2 in mice protects against hepatic steatosis and steatohepatitis:a novel therapeutic target for fatty liver disease

Fatty liver disease is a serious health problem worldwide and is the most common cause for chronic liver disease and metabolic disorders.The major challenge in the prevention and intervention of this disease is the incomplete understanding of the underlying mechanism and thus lack of potent therapeutic targets due to multifaceted and interdependent disease factors.In this study,we investigated the role of a signaling adaptor protein,GRB2-associated-binding protein 2(Gab2),in fatty liver using an animal disease model.Gab2 expression in hepatocytes responded to various disease factor stimulations,and Gab2 knockout mice exhibited resistance to fat-induced obesity,fat-or alcohol-stimulated hepatic steatosis,as well as methionine and choline deficiency-induced steatohepatitis.Concordantly,the forced expression or knockdown of Gab2 enhanced or diminished oleic acid(OA)-or ethanol-induced lipid production in hepatocytes in vitro,respectively.During lipid accumulation in hepatocytes,both fat and alcohol induced the recruitment of PI3K or Socs3 by Gab2 and the activation of their downstream signaling proteins AKT,ERK,and Stat3.Therefore,Gab2 may be a disease-associated protein that is induced by pathogenic factors to amplify and coordinate multifactor-induced signals to govern disease development in the liver.Our research provides a novel potential target for the prevention and intervention of fatty liver disease.

Repurposing of Antazoline Hydrochloride as an Inhibitor of Hepatitis B Virus DNA Secretion

Hepatitis B virus(HBV) belongs to Hepadnaviridae family and mainly infects hepatocytes, which can cause acute or chronic hepatitis. Currently, two types of antiviral drugs are approved for chronic infection clinically: interferons and nucleos(t)ide analogues. However, the clinical cure for chronic infection is still rare, and it is a huge challenge for all researchers to develop high-efficiency, safe, non-tolerant, and low-toxicity anti-HBV drugs. Antazoline hydrochloride is a first-generation antihistamine with anticholinergic properties, and it is commonly used to relieve nasal congestion and in eye drops. Recently, an in vitro high-throughput evaluation system was constructed to screen nearly 800 compounds from the Food and Drug Administration(FDA)-approved Drug Library. We found that arbidol hydrochloride and antazoline hydrochloride can effectively reduce HBV DNA in the extracellular supernatant in a dose-dependent manner, with EC_(50) of4.321 lmol/L and 2.910 lmol/L in HepAD38 cells, respectively. Moreover, the antiviral effects and potential mechanism of action of antazoline hydrochloride were studied in different HBV replication systems. The results indicate that antazoline hydrochloride also has a significant inhibitory effect on HBV DNA in the extracellular supernatant of Huh7 cells,with an EC_(50) of 2.349 lmol/L. These findings provide new ideas for screening and research related to HBV agents.