Sensing polymer/DNA polyplex dissociation using quantum dot fluorophores

We characterized the dissociation of polymer/DNA polyplexes designed for gene delivery using water-soluble quantum dots (QDs). A pH-responsive pentablock copolymer was designed to form stable complexes with plasmid DNA via tertiary amine segments. Dissociation of the polyplex was induced using chloroquine where the efficiency of this process was sensed through changes in QD fluorescence. We found that increasing concentrations of pentablock copolymer and DNA led to quenching of QD fluorescence, while chloroquine alone had no measurable effect. The mechanism of quenching was elucidated by modeling the process as the combination of static and dynamic quenching from the pentablock copolymer and DNA, as well as self-quenching due the bridging of QDs. Tertiary amine homopolymers were also used to study the effect of chain length on quenching. Overall, these QDs were found to be highly effective at monitoring the dissociation of pentablock copolymer/DNA polyplexes in vitro and may have potential for studying the release of DNA within cells

Sr and Mn co-doped LaCuSO: A wide band gap oxide diluted magnetic semiconductor with TC around 200K

Here we report the synthesis of a bulk oxide diluted magnetic semiconductor (DMS) system La1-xSrxCu0.925Mn0.075SO (x=0, 0.025, 0.05, 0.075, and 0.1). As a wide band gap p-type oxide semiconductor, LaCuSO satisfies all the conditions forecasted theoretically to be a room temperature DMS. The Curie temperature (TC) is around 200K as x>0.05, which is among the highest TC record of known bulk DMS materials up to now. The system provides a rare example of oxide DMS system with p-type conduction, which is important for formation of high temperature spintronic devices.Comment: 10 pages, 3 figure

Magnetic property and crystalline electric field effect in ThCr2_2Si2_2-type CeNi2_2As2_2

Millimeter sized ThCr$_2$Si$_2$-type CeNi$_2$As$_2$ single crystal was synthesized by NaAs flux method and its physical properties were investigated by magnetization, transport and specific heat measurements. In contrast to the previously reported CaBe$_2$Ge$_2$-type CeNi$_2$As$_2$, the ThCr$_2$Si$_2$-type CeNi$_2$As$_2$ is a highly anisotropic uniaxial antiferromagnet with the transition temperature $T_N$=4.8 K. A field induced spin flop transition was seen below $T_N$ when the applied $\textbf{B}$ is parallel to the $\textbf{c}$-axis, the magnetic easy axis, together with a huge frustration parameter $f=\theta_W/T_N$. A pronounced Schottky-like anomaly in specific heat was also found around 160 K, which could be attributed to the crystalline electric field effect with the excitation energies being fitted to $\Delta_1=$325 K and $\Delta_2=$520 K, respectively. Moreover, the in-plane resistivity anisotropy and low temperature X-ray diffractions suggest that this compound is a rare example exhibiting a possible structure distortion induced by the $4f$-electron magnetic frustration.Comment: 10 pages, 9 figures, 2 table

A Two-Habit Ice Cloud Optical Property Parameterization for GCM Application

We present a novel ice cloud optical property parameterization based on a two-habit ice cloud model that has been proved to be optimal for remote sensing applications. The two-habit ice model is developed with state-of-the-art numerical methods for light scattering property calculations involving individual columns and column aggregates with the habit fractions constrained by in-situ measurements from various field campaigns. Band-averaged bulk ice cloud optical properties including the single-scattering albedo, the mass extinction/absorption coefficients, and the asymmetry factor are parameterized as functions of the effective particle diameter for the spectral bands involved in the broadband radiative transfer models. Compared with other parameterization schemes, the two-habit scheme generally has lower asymmetry factor values (around 0.75 at the visible wavelengths). The two-habit parameterization scheme was widely tested with the broadband radiative transfer models (i.e. Rapid Radiative Transfer Model, GCM version) and global circulation models (GCMs, i.e. Community Atmosphere Model, version 5). Global ice cloud radiative effects at the top of the atmosphere are also analyzed from the GCM simulation using the two-habit parameterization scheme in comparison with CERES satellite observations

Self-assembled pentablock copolymers for selective and sustained gene delivery

The poly(diethylaminoethyl methacrylate) (PDEAEM) - Pluronic F127 - PDEAEM pentablock copolymer (PB) gene delivery vector system has been found to possess an inherent selectivity in transfecting cancer cells over non-cancer cells in vitro, without attaching any targeting ligands. In order to understand the mechanism of this selective transfection, three possible intracellular barriers to transfection were investigated in both cancer and non-cancer cells. We concluded that escape from the endocytic pathway served as the primary intracellular barrier for PB-mediated transfection. Most likely, PB vectors were entrapped and rendered non-functional in acidic lysosomes of non-cancer cells, but survived in less acidic lysosomes of cancer cells. The work highlights the importance of identifying intracellular barriers for different gene delivery systems and provides a new paradigm for designing targeting vectors based on intracellular differences between cell types, rather than through the use of targeting ligands. The PB vector was further developed to simultaneously deliver anticancer drugs and genes, which showed a synergistic effect demonstrated by significantly enhanced gene expression in vitro. Due to the thermosensitive gelation behavior, the PB vector packaging both drug and gene was also investigated for its in vitro sustained release properties by using polyethylene glycol diacrylate as a barrier gel to mimic the tumor matrix in vivo. Overall, this work resulted in the development of a gene delivery vector for sustained and selective gene delivery to tumor cells for cacner therapy

Geomorphological Evolution and Palaeoenvironmental Change in the Western Alashan Plateau, China

Although neotectonic activity is considered to be the main factor of theterrain evolution of the Qinghai Tibet Plateau and its surrounding high-altitude areas, further geomorphological analysis and literature analysis areneeded for the understanding of the geomorphic evolution and the Quaternary environment change of the western area of the Alxa Plateau nearthe northern Tibet Plateau. The purpose of this study is to investigate thedistribution of site-specific geomorphic units of the landforms developedin the vast topography of Ejina Basin (Western Alxa), in order to identifythe geostructural and climatic causes of the geomorphic landscape and itsimpact on the change of paleoenvironment. At present, the climate andhydrological conditions in Ejina are relatively monotonous and stable. Inaddition to tectonic dynamic factors, the most widely distributed landform in the basin is climate landform. There are both geomorphologicaland sedimentological anomalies of Aeolian landforms occurred in thewhole basin, indicating that the underlying surface effect (retention effect) of river (Ejina River) and its related uneven ground and weak winderosion (deflation) process in the nearby area may be the important factors controlling the formation of Ejina dunes, rather than the arid climate.It is believed that the extensive interaction between the aeolian and fluvialprocesses is the main mechanism of the regional geomorphic difference inEjina Basin. According to the comparability of regional geomorphologyand sedimentology, the period of the formation of relic geomorphologyin the edge of Ejina Basin can be reasonably attributed to the local glacialmaximum of the last glacial. The geomorphic transformation from quasiplain and desert valley to desert plain, the appearance of widely movingsand dunes and the presence of large ancient lake geomorphology allindicate that the drought index of Ejina Basin is increasing on the scaleof geomorphic formation. Paleogeomorphological and chronological evidences show that the climatic and hydrological conditions of the basin inthe last glacial period and the early Holocene are much better than thoseat present. For example, the average annual precipitation in the area before 39-23ka BP is between 60-350 mm (about 36 mm today), but thereare large waves in the Holocene. The coexistence of various climates andlandforms in Ejina Basin and the resulting geomorphic diversity shouldbe the composite result of various geomorphic processes and surface processes besides glaciation. The low aridity (relative humidity) in the EjinaRegion in the late Pleistocene may be the result of the enhancement of thewesterly rain belt and the weakening of the Asian Winter Monsoon in thearid region of Central Asia

Impact of Radiatively Interactive Dust Aerosols in the NASA GEOS-5 Climate Model: Sensitivity to Dust Particle Shape and Refractive Index

We investigate the radiative effects of dust aerosols in the NASA GEOS-5 atmospheric general circulation model. GEOS-5 is improved with the inclusion of a sectional aerosol and cloud microphysics module, the Community Aerosol and Radiation Model for Atmospheres (CARMA). Into CARMA we introduce treatment of the dust and sea salt aerosol lifecycle, including sources, transport evolution, and sinks. The aerosols are radiatively coupled to GEOS-5, and we perform a series of multi-decade AMIP-style simulations in which dust optical properties (spectral refractive index and particle shape distribution) are varied. Optical properties assuming spherical dust particles are from Mie theory, while those for non-spherical shape distributions are drawn from a recently available database for tri-axial ellipsoids. The climatologies of the various simulations generally compare well to data from the MODIS, MISR, and CALIOP space-based sensors, the ground-based AERONET, and surface measurements of dust deposition and concentration. Focusing on the summertime Saharan dust cycle we show significant variability in our simulations resulting from different choices of dust optical properties. Atmospheric heating due to dust enhances surface winds over important Saharan dust sources, and we find a positive feedback where increased dust absorption leads to increased dust emissions. We further find that increased dust absorption leads to a strengthening of the summertime Hadley cell circulation, increasing dust lofting to higher altitudes and strengthening the African Easterly Jet. This leads to a longer atmospheric residence time, higher altitude, and generally more northward transport of dust in simulations with the most absorbing dust optical properties. We find that particle shape, although important for radiance simulations, is a minor effect compared to choices of refractive index, although total atmospheric forcing is enhanced by greater than 10 percent for simulations incorporating a spheroidal shape distribution versus ellipsoidal or spherical shapes

Información y complejidad: el papel de la comunicación según el pensamiento complejo de Edgar Morin

La presente investigación se centra en las ideas desarrolladas por el filósofo, epistemólogo y sociólogo, Edgar Morin. Hemos tratado de establecer las articulaciones del pensamiento del autor alrededor de la idea de comunicación a lo largo de su obra (especialmente en su primera época de pensamiento sobre el método). En la primera parte se recogen las principales ideas que definen el Pensamiento Complejo para organizarlas de forma operativa para poder llegara la segunda parte, la aplicación al análisis y descripción de un sistema representado, es decir, la organización de un sistema textual en sus niveles que van desde el lenguaje a las manifestaciones de la Historia, la Política o la Economía..