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The resolution of multiple targets at the same range cell but different angles in the forward-looking direction is of great trouble for active radar. Based on compressive sensing (CS) framework, a sparse scenario imaging approach using joint angle-Doppler representation basis is proposed, which employs multisensor and single-receiver channel hardware architecture. Firstly, the joint angle-Doppler representation basis is formulated using the Doppler dictionary, and then the radar returns during multiple pulse repetition periods are modeled as the measurements with respect to a stationary sparse target scenario via the joint representation basis; in the end, the image of sparse target scenario is recovered using the single-receiver echoes. Numerical experiments demonstrate that the proposed method can provide an image of the spatial sparse scenario at the same range for active radar in the forward-looking direction.

A novel series of carbamate-linked cationic lipids containing hydroxyl headgroup were synthesized and included in formulations for transfection assays. The DNA–lipid complexes were characterized for their ability to bind DNA, their size, ζ-potential and cytotoxicity. Compared with our previously reported cationic transfection lipid DDCDMA lacking the hydroxyl group and the commercially available, these cationic liposomes exhibited relatively higher transfection efficiency.

Cationic lipids are one of the most widely used nonviral vectors for gene delivery and are especially attractive because they can be easily synthesized and extensively characterized. Additionally, they can best facilitate the elucidation of structure-activity relationships by modifying each of their constituent domains. The polar hydrophilic headgroups enable the condensation of nucleic acids by electrostatic interactions with the negatively charged phosphate groups of the genes, and further govern transfection efficiency. The headgroups of cationic lipids play a crucial role for gene delivery; they can be quaternary ammoniums, amines, aminoacids or peptides, guanidiniums, heterocyclic headgroups, and some unusual headgroups. This review summarizes recent research results concerning the nature (such as the structure and shape of cationic headgroup) and density (such as the number and the spacing of cationic headgroup) of head functional groups for improving the design of efficient cationic lipids to overcome the critical barriers of in vitro and in vivo transfection.

Strong spectral softening has been revealed in the late X-ray afterglows of some gamma-ray bursts (GRBs). The scenario of X-ray scattering around circum-burst dusty medium has been supported by previous works due to its overall successful prediction of both the temporal and spectral evolution of some X-ray afterglows. To further investigate the observed feature of spectral softening, we now systematically search the X-ray afterglows detected by X-Ray Telescope (XRT) of Swift and collect twelve GRBs with significant late-time spectral softening. We find that dust scattering could be the dominant radiative mechanism for these X-ray afterglows regarding their temporal and spectral features. For some well observed bursts with high-quality data, their time-resolved spectra could be well produced within the scattering scenario by taking into account the X-ray absorption from circum-burst medium. We also find that during spectral softening the power-law index in the high energy end of the spectra does not vary much. The spectral softening is mainly manifested by the spectral peak energy continually moving to the soft end., Accepted for publication in ApJ; 25 pages, 2 figures

In order to study the efficiency of small interfering RNA (siRNA) transfer mediated by cationic liposome, we used luciferase siRNA to evaluate the gene silencing activity in the Hep-2 cells, which were stably transduced with a luciferase gene. The pDNA transfection was studied, and siRNA arrearage assay was conducted to determine the capability of cationic liposome with siRNA. Different concentrations of siRNA was used to silence luciferase gene' activity, and then the result was examined by microplate reader. Cell viability was analyzed after transfection by MTT assay. The results suggested that Lipofectamine 2000 could transfer the pDNA efficiently, and have strong binding capacity with siRNA. The silencing efficiency of luciferase was obtained with low concentration of siRNA. The cell viability was influenced by RNA interference (RNAi) very slightly, but the cell survival rate decreased with the increase of siRNA concentrations. It was well concluded that by optimizing the experimental conditions, cationic liposome can transfer low concentration siRNA to silence target gene's activity efficiently.

The all-fiber optical current transformer (A-FOCT) is based on the Faraday magnetic rotation effect for current measurement, and utilize closed-loop digital control which is to adapt the demand of future smart grid development. In this paper, the origin of linear birefringence in sensing coil was analyzed. The effect of linear birefringence on the measurement system error was investigated. The mathematical model was established, based on which, the simulation was performed to discuss the correlation among the sensing coil sizes, linear birefringence and fiber optical materials, and the size of sensing coil was optimized.

The principle of Pockels effect optical voltage sensor has been introduced. Review of some optical voltage transducer based on Pockels electro-optic effect has been presented, and their disadvantages have been pointed out, else. A voltage transducer with capacitive divider has been designed based on Pockels effect. The results of type test show that it can be used as the electronic voltage transducer for measurement in level 0.2 and protection in level 3P, according to the IEC60044-7 standards.

As an important type of nonviral gene delivery vector, peptide-based cationic liposomes have shown many advantages over other cationic liposomes, such as good biodegradability, excellent biocompatibility and targeting ability to cells, and great potential application in improving the delivery of gene therapeutics.This article reviews the research progress on peptide-based cationic liposomes for gene delivery, including the structure characteristics of peptide lipids, the development of peptide cationic liposomes and three special types of peptide cationic liposomes: peptide-based Gemini lipids, lipitoids and lipids with cholesterol hydrophobic group. This review hopes to provide some suggestions on the design of peptide cationic lipids and insight into their development trend in the field of gene delivery.As peptide-based cationic liposomes still hold some limitations, future research needs to select suitable peptide heads and investigate the surface modification of peptide cationic liposomes, in order to facilitate targeting and reduce cytotoxicity.

Over the last few decades, as a promising strategy for the treatment of many refractory diseases, such as inherited diseases (Martin-Rendon & Blake, 2003) and acquired immunodeficiency syndrome (AIDS) (Fanning et al., 2003), gene therapy, the objective to allow a gene to express the protein coded in the target cells and consequently to treat disease by the protein secreted from cells transfected, has become an invaluable experimental tool to study gene function and its regulation (El-Aneed, 2004). The success of gene therapy critically depends on suitable transfection vectors, which have the high efficiency transfer of genes to target cells as well as a favorable safety profile. Broadly, these vectors are mainly classified into two categories: viral and non-viral (Liu & Huang, 2002). Currently, viral vectors based on many different viruses such as adenovirus and retrovirus have achieved some success particularly in cancer gene therapy (Williams et al., 2010), and their performance and pathogenicity have been evaluated in animal models. However, several issues including difficulty in production, limited opportunity for repeated administrations due to acute inflammatory response, and delayed humeral or cellular immune responses need to be addressed, so that their clinical potential can be fully realized (Love et al., 2010). Thus it is necessary to develop more efficient and flexible security system in the category of vectors for gene delivery. Synthetic non-viral vectors are potential alternatives to viral vectors, and may help to overcome some of these problems (Zhang et al., 2010). Among these, cationic compounds (mainly including cationic lipids and cationic polymers) are believed to cause less safety problems due to their relative simplicity, and have been the most extensively studied. Since the first description of successful in vitro transfection with cationic lipid by Felgner et al. in 1987 (Felgner et al., 1987), numerous cationic lipids have been synthesised and used for delivery of nucleic acids into cells during the last 20 years. Cationic liposomes are composed of lipid constituents, and have improved the gene delivery efficacy owing to their typical bilayer structure. Some helper lipids such as dioleylphosphatidyl choline (DOPC) or dioleylphosphatidyl ethanolamine (DOPE), typically neutrally lipids (Zuhorn et al., 2005), are often employed with cationic lipids, and play very important role during the formation of lipoplexes by combining cationic liposomes and genes, as they could determine the morphologies of lipoplexes.

We have introduced a convenient synthesis method for carbamate-linked cationic lipids. Two cationic lipids N-[1-(2,3-didodecylcarbamoyloxy)propyl]-N,N,N-trimethylammonium iodide (DDCTMA) and N-[1-(2,3-didodecyl carbamoyloxy)propyl]-N-ethyl-N,N-dimethylammonium iodide (DDCEDMA), with identical length of hydrocarbon chains, alternative quaternary ammonium heads, carbamate linkages between hydrocarbon chains and quaternary ammonium heads, were synthesized for liposome-mediated gene delivery. Liposomes composed of DDCEDMA and DOPE in 1:1 ratio exhibited a lower zeta potential as compared to those made of pure DDCEDMA alone, which influences their DNA-binding ability. pGFP-N2 plasmid was transferred by cationic liposomes formed from the above cationic lipids into Hela and Hep-2 cells, and the transfection efficiency of some of cationic liposomes was superior or parallel to that of two commercial transfection agents, Lipofectamine2000 and DOTAP. Combined with the results of the agarose gel electrophoresis and transfection experiment, the DNA-binding ability of cationic lipids was too strong to release DNA from complex in the transfection, which could lead to relative low transfection efficiency and high cytotoxicity.

The structure of cationic lipids is a major factor for their transfection activity. A cationic lipid generally contains four functional domains: a hydrophilic headgroup, a linker, a backbone domain, and a hydrophobic domain. The structure of the hydrophobic domain determines the phase transition temperature and the fluidity of the bilayer and influences the stability of liposomes, the DNA protection from nucleases, the endosomal escape, the DNA release from complex, and the nuclear penetration. Also, toxicity of the lipids is influenced by the hydrophobic domain. The compounds used for gene delivery are classified according to the structure of the hydrophobic domain as follows: aliphatic chains, steroid domain, and fluorinated domain. In this review, we summarized recent research results concerning the structures of the hydrophobic domain, in order to find the effect of the hydrophobic domain on transfection efficiency. Understanding these would be very important for scientists to prepare novel cationic lipids and design novel formulations with high transfection efficiency.

Characteristics of practical logarithmic detectors are investigated and the moments and cumulants of this type detector are determined. The integration PDF for n pulses at the output of this type detector in Rayleigh interference is approximated with Edgeworth series expansion. The accuracy of this series expansion can be controlled because of its convergence property.

Modifying chitosan (CS) with polyethylenimine (PEI) grafts is an effective way to improve its gene transfection performance. However, it is still a challenge to conduct the grafting with fine control and high efficiency, particularly for the modification of water-insoluble CS. Herein, a novel method to graft CS with PEI (1.8 kDa, PEI-1.8) was developed by using ionic liquid 1-butyl-3-methyl imidazolium acetate ([BMIM]Ac) as a reaction solvent, water-insoluble CS as a reaction substrate and 1,1-carbonyldiimidazole (CDI) as a linking agent. The grafting reaction was greatly accelerated and the reaction time was largely shortened to 4 h by taking advantages of the good solubility of CS, the enhanced nucleophilicity of amino groups and the preferential stability of the activated complexes in the ionic liquid. The chitosan-graft-polyethylenimine (CS-g-PEI) products were characterized by 1H NMR, FTIR and GPC. PEI-1.8 was quantitatively grafted to CS through urea linkages, and the grafting degree (GD) was conveniently tuned by varying the molar ratios of PEI-1.8 to D-glucosamine units of CS in the range of 9.0 × 10(-3) to 9.0 × 10(-2). Compared with CS, the synthesized CS-g-PEI copolymers showed higher pDNA-binding affinity, which increased with the GD as shown in Agarose gel electrophoresis. The dynamic light scattering (DLS) experiment demonstrated that the CS-g-PEI/pDNA polyplexes had suitable particle sizes and proper ζ-potentials for cell transfection. The CS-g-PEI copolymer with a medium GD of 4.5% conferred the best gene transfection, with the efficiency 44 times of CS and 38 times of PEI-1.8 in HEp-2 cells. The cytotoxicity of CS-g-PEI was tested and found nearly as low as that of CS and much lower than that of PEI.

The Lowest Unique Bid Auction (LUBA) booms recently through the Internet. A typical distribution pattern of bid price in this reverse auction has been found and needs to be interpreted. The distribution curve is a decreasing one whose slope has a close relationship with the number of agents participating in the auction. To explain this stylized fact, we develop a model assuming that agents prefer to bid on the price at which the probability of winning is higher. The bid distributions of actual auctions with the number of agents less than 200 can be fitted very well using the parameters for the value of items and the number of bids. When this number becomes larger, however, a deviation occurs between prediction and empirical data, which can be adjusted by introducing cognitive illusion of the bid number.