International audienceLocal Binary Patterns (LBP) is a non-parametric descriptor whose aim is to efficiently summarize the local structures of images. In recent years, it has aroused increasing interest in many areas of image processing and computer vision, and has shown its effectiveness in a number of applications, in particular for facial image analysis, including tasks as diverse as face detection, face recognition, facial expression analysis, demographic classification, etc. This paper presents a comprehensive survey of LBP metho-dology including several more recent variations. As a typical ap-plication of the LBP approach, LBP-based facial image analysis is extensively reviewed, while its successful extensions in dealing with various tasks of facial image analysis are also highlighted

In this review, we focus on the types of smart supramolecular gels whose self-assembly processes are affected or even triggered by physical forces including sonication and mechanical stress (mechanical force). The types of gels that are responsive to sonication and mechanical stress are examined and summarised. The gels exhibit non-covalent interactions among the gelator molecules and show dynamic and reversible properties controlled by the stimuli. Upon stimulation, the gelators cause instant and in situ gelation of organic solvents or water with different modes and outcomes of self-assembly. On the other hand, sonication and mechanical stress, as external factors, can give rise to dynamic changes in microscopic morphology, optical properties, etc. Certain thixotropic supramolecular gels exhibit perfect self-healing characteristics. The driving forces and the mechanism of the self-assembly process and the responsive outcome of morphological and spectroscopic changes are discussed. Those supramolecular gels responding to sonication and mechanical stress offer a wide range of applications in fields such as smart and adaptive materials, switches, drug control and release, and tissue engineering.

Two low molecular weight gelators containing 4-ethynyl-1,8-naphthalimide groups with large conjugated structure via different length of alkyl chains were synthesized and fully characterized. The gelation properties, structural character, and fluorescence of the gels were investigated via methods of scanning electron microscopy, X-ray diffraction, and spectral studies. The gelators have high fluorescence quantum yields in both solution and solid state. Interestingly, the wavelength of the fluorescent emission in the reversible sol-gel transition process of the gels has a large red-shift of 80 nm in DMF, which is extremely sparse for 1,8-naphthalimide derivatives in the literature. The intermolecular π-π stacking between naphthalimide is suggested to be the main driving force for the gel formation and fluorescent variation by means of temperature-dependent (1)H NMR study and theoretical calculation.

Two new peptide-based isomers containing cholesterol and naphthalic groups have been designed and synthesized. We found that the position of L-alanine in the linker could tune the gelation properties and morphologies. The molecule with the L-alanine residue positioned in the middle of the linker (1b) shows better gelation behavior than that with L-alanine directly linked to the naphthalimido moiety (1a). As a result, a highly thermostable organogel of 1b with a unique core-shell structure was obtained at high temperature and pressure in acetonitrile. Moreover, the gels of 1a and 1b could undergo an instantaneous gel-to-gel transition triggered by sonication. Ultrasound could break the core-shell microsphere of 1b and the micelle structure of 1a into entangled fibers. By studying the mechanism of the sonication-triggered gel-to-gel transition process of these compounds, it can be concluded that ultrasound has a variety of effects on the morphology, such as cutting, knitting, unfolding, homogenizing, and even cross-linking. Typically, ultrasound can cleave and homogenize pi-stacking and hydrophobic interactions among the gel molecules and then reshape the morphologies to form a new gel. This mechanism of morphology transformation triggered by sonication might be attractive in the field of material storage and controlled release.

No abstract

No abstract

It is important to detect hydrogen peroxide (H2O2) near mitochondrial DNA (mtDNA) because mtDNA is more prone to oxidative attack than nuclear DNA (nDNA). In this study, a mitochondria-targeted fluorescence probe, pep3-NP1, has been designed and synthesized. The probe contains a DNA-binding peptide, a H2O2 fluorescence reporter, and a positively charged red emissive styryl dye to facilitate accumulation in mitochondria. Due to groove binding of the peptide with DNA, the styryl dye of pep3-NP1 intercalated into the bases of DNA, leading to an increase in red fluorescence intensity (centered at 646 nm) and quantum yield. In this case, pep3-NP1 was a turn-on probe for labeling DNA. Subcellular locations of pep3-NP1 and MitoTracker suggested that pep3-NP1 mostly accumulated in the mitochondria of live cells. Namely, as an intracellular DNA marker, pep3-NP1 bound to mtDNA. In the presence of H2O2, pep3-NP1 emitted green fluorescence (centered at 555 nm). Thus, the ratio of green with red fluorescence of pep3-NP1 was suitable to reflect the change of the H2O2 level near mtDNA in living cells. The detecting limit for H2O2 was estimated at 2.9 and 5.0 μM in vitro and in cultured cells, respectively. The development of pep3-NP1 could help in studies to protect mtDNA from oxidative stress.

No abstract