Showing papers by "Di Li published in 2016"

Toward Efficient Orange Emissive Carbon Nanodots through Conjugated sp(2) -Domain Controlling and Surface Charges Engineering.

Abstract: A strategy of achieving efficient orange emissive carbon nanodots (CNDs) with large sized conjugated sp(2) -domain is achieved in a solvothermal synthetic route using dimethylformamide as solvent, which is the basis of orange bandgap emission; enhanced orange emission with photoluminescent quantum yield of 46% is realized through surface charges engineering by surface metal-cation-functionalization.

Supra-(carbon nanodots) with a strong visible to near-infrared absorption band and efficient photothermal conversion

Abstract: A novel concept and approach to engineering carbon nanodots (CNDs) were explored to overcome the limited light absorption of CNDs in low-energy spectral regions. In this work, we constructed a novel type of supra-CND by the assembly of surface charge-confined CNDs through possible electrostatic interactions and hydrogen bonding. The resulting supra-CNDs are the first to feature a strong, well-defined absorption band in the visible to near-infrared (NIR) range and to exhibit effective NIR photothermal conversion performance with high photothermal conversion efficiency in excess of 50%.

Hierarchically Structured Porous Nitrogen-Doped Carbon for Highly Selective CO2 Capture

Abstract: Nitrogen-doping has proven to be an effective strategy for enhancing the CO2 adsorption capacity of carbon-based adsorbents. However, it remains challenging to achieve a high doping level of nitrogen (N) and a significant porosity in a carbon material simultaneously. Here we report a facile method that enables the fabrication of ordered macroporous nitrogen-doped carbon with the content of N as high as 31.06 wt %. Specifically, we used poly(EGDMA-co-MAA) microspheres as a template to fabricate the structure which can strongly interact with melamine (the precursor of nitrogen-doped carbon framework), self-assemble into three-dimensionally ordered structure, and be easily removed afterward. Upon chemical activation, significant microporosity is generated in this material without degrading its ordered macroporous structure, giving rise to a hierarchically structured porous nitrogen-doped carbon in which a remarkable N content (14.45 wt %) is retained. This material exhibits a moderate CO2 adsorption capacity...

Evolution of oh and co-dark molecular gas fraction across a molecular cloud boundary in taurus

Abstract: We present observations of (CO)-C-12 J = 1-0, (CO)-C-13 J = 1-0, H I, and all four ground-state transitions of the hydroxyl (OH) radical toward a sharp boundary region of the Taurus molecular cloud. Based on a photodissociation region (PDR) model that reproduces CO and [C I] emission from the same region, we modeled the three OH transitions, 1612, 1665, and 1667 MHz successfully through escape probability non-local thermal equilibrium radiative transfer model calculations. We could not reproduce the 1720 MHz observations, due to unmodeled pumping mechanisms, of which the most likely candidate is a C-shock. The abundance of OH and CO-dark molecular gas is well-constrained. The OH abundance [OH]/[H-2] decreases from 8 x 10(-7) to 1 x 10(-7) as A, increases from 0.4 to 2.7 mag following an empirical law:

The Five-hundred-meter Aperture Spherical Radio Telescope project

Abstract: The Five-hundred-meter Aperture Spherical Radio Telescope (FAST) is a Chinese megascience project funded by the National Development and Reform Commission (NDRC) of the People's Republic of China The National Astronomical Observatories of China (NAOC) is in charge of its construction and subsequent operation Upon its expected completion in September 2016, FAST will surpass the 305 m Arecibo Telescope and the 100 m Green Bank Telescope in terms of absolute sensitivity in the 70 MHz to 3 GHz bands In this paper, we report on the project, its current status, the key science goals, and plans for early science

Evolution of OH and CO-dark Molecular Gas Fraction Across a Molecular Cloud Boundary In Taurus

Abstract: We present observations of 12CO J=1-0, 13CO J=1-0, HI, and all four ground-state transitions of the hydroxyl (OH) radical toward a sharp boundary region of the Taurus molecular cloud. Based on a PDR model that reproduces CO and [CI] emission from the same region, we modeled the three OH transitions, 1612, 1665, 1667 MHz successfully through escape probability non-LTE radiative transfer model calculations. We could not reproduce the 1720 MHz observations, due to un-modeled pumping mechanisms, of which the most likely candidate is a C-shock. The abundance of OH and CO-dark molecular gas (DMG) are well constrained. The OH abundance [OH]/[H2] decreases from 8*10-7 to 1*10-7 as Av increases from 0.4 to 2.7 mag, following an empirical law [OH]/[H2]= 1.5 * 10^{-7} + 9.0 * 10^{-7} * exp(-Av/0.81), which is higher than PDR model predictions for low extinction regions by a factor of 80. The overabundance of OH at extinctions at or below 1 mag is likely the result of a C-shock. The dark gas fraction (DGF, defined as fraction of molecular gas without detectable CO emission) decreases from 80% to 20%, following a gaussian profile DGF= 0.90 * exp(-( Av -0.79 )/0.71)^2) This trend of the DGF is consistent with our understanding that the DGF drops at low visual extinction due to photodissociation of H2 and drops at high visual extinction due to CO formation. The DGF peaks in the extinction range where H2 has already formed and achieved self-shielding but 12CO has not. Two narrow velocity components with a peak-to-peak spacing of ~ 1 km s-1 were clearly identified. Their relative intensity and variation in space and frequency suggest colliding streams or gas flows at the boundary region.

Cloud structure of galactic OB cluster-forming regions from combining ground- and space-based bolometric observations

Abstract: We have developed an iterative procedure to systematically combine the millimeter and submillimeter images of OB cluster-forming molecular clouds, which were taken by ground-based (CSO, JCMT, APEX, and IRAM-30 m) and space telescopes (Herschel and Planck). For the seven luminous (L > 10(6) L-circle dot) Galactic OB cluster-forming molecular clouds selected for our analyses, namely W49A, W43-Main, W43-South, W33, G10.6-0.4, G10.2-0.3, and G10.3-0.1, we have performed single-component, modified blackbody fits to each pixel of the combined (sub) millimeter images, and the Herschel PACS and SPIRE images at shorter wavelengths. The similar to 10 '' resolution dust column density and temperature maps of these sources revealed dramatically different morphologies, indicating very different modes of OB cluster-formation, or parent molecular cloud structures in different evolutionary stages. The molecular clouds W49A, W33, and G10.6-0.4 show centrally concentrated massive molecular clumps that are connected with approximately radially orientated molecular gas filaments. The W43-Main and W43-South molecular cloud complexes, which are located at the intersection of the Galactic near 3 kpc (or Scutum) arm and the Galactic bar, show a widely scattered distribution of dense molecular clumps/cores over the observed similar to 10 pc spatial scale. The relatively evolved sources G10.2-0.3 and G10.3-0.1 appear to be affected by stellar feedback, and show a complicated cloud morphology embedded with abundant dense molecular clumps/cores. We find that with the high angular resolution we achieved, our visual classification of cloud morphology can be linked to the systematically derived statistical quantities (i.e., the enclosed mass profile, the column density probability distribution function (N-PDF), the two-point correlation function of column density, and the probability distribution function of clump/core separations). In particular, the massive molecular gas clumps located at the center of G10.6-0.4 and W49A, which contribute to a considerable fraction of their overall cloud masses, may be special OB cluster-forming environments as a direct consequence of global cloud collapse. These centralized massive molecular gas clumps also uniquely occupy much higher column densities than what is determined by the overall fit of power-law N-PDF. We have made efforts to archive the derived statistical quantities of individual target sources, to permit comparisons with theoretical frameworks, numerical simulations, and other observations in the future.

Planck Cold Clumps in the λ Orionis Complex. I : Discovery of an Extremely Young Class 0 Protostellar Object and a Proto-brown Dwarf Candidate in the Bright-rimmed Clump PGCC G192.32-11.88

Abstract: We are performing a series of observations with ground-based telescopes toward Planck Galactic cold clumps (PGCCs) in the lambda Orionis complex in order to systematically investigate the effects of stellar feedback. In the particular case of PGCC G192.32-11.88, we discovered an extremely young Class 0 protostellar object (G192N) and a proto-brown dwarf candidate (G192S). G192N and G192S are located in a gravitationally bound brightrimmed clump. The velocity and temperature gradients seen in line emission of CO isotopologues indicate that PGCC G192.32-11.88 is externally heated and compressed. G192N probably has the lowest bolometric luminosity (similar to 0.8 L-circle dot) and accretion rate (6.3 x 10(-7) M-circle dot yr(-1)) when compared with other young Class 0 sources (e.g., PACS Bright Red Sources) in the Orion complex. It has slightly larger internal luminosity (0.21 +/- 0.01 L-circle dot) and outflow velocity (similar to 14 km s(-1)) than the predictions of first hydrostatic cores (FHSCs). G192N might be among the youngest Class 0 sources, which are slightly more evolved than an FHSC. Considering its low internal luminosity (0.08 +/- 0.01 L-circle dot) and accretion rate (2.8 x 10(-8) M-circle dot yr(-1)), G192S is an ideal proto-brown dwarf candidate. The star formation efficiency (similar to 0.3%-0.4%) and core formation efficiency (similar to 1%) in PGCC G192.32-11.88 are significantly smaller than in other giant molecular clouds or filaments, indicating that the star formation therein is greatly suppressed owing to stellar feedback.

Discovery of two new pulsars in 47 Tucanae (NGC 104)

Abstract: We report the discovery of two new millisecond pulsars (PSRs J0024$-$7204aa and J0024$-$7204ab) in the globular cluster 47\,Tucanae (NGC 104). Our results bring the total number of pulsars in 47\,Tucanae to 25. These pulsars were discovered by reprocessing archival observations from the Parkes radio telescope. We reprocessed the data using a standard search procedure based on the PRESTO software package as well as using a new method in which we incoherently added the power spectra corresponding to $\sim$1100\,hr of observations. The newly discovered PSR~J0024$-$7204aa, has a pulse frequency of $\rm \sim$541\,Hz (corresponding to a $\rm \sim$1.84 ms period), which is higher than any other pulsars currently known in the cluster and ranks 12$^{\rm{th}}$ amongst all the currently known pulsars. The dispersion measure of this pulsar, 24.941(7)\,cm$^{-3}$ pc, is the highest in the cluster. The second discovered pulsar, PSR~J0024$-$7204ab, is an isolated pulsar with a pulse frequency of $\rm \sim$270\,Hz (corresponding to a period of $\rm \sim$3.70 ms).

Drug binding rate regulates the properties of polysaccharide prodrugs

Abstract: Three intracellular acid-degradable hydroxyethyl starch–doxorubicin (HESDOX) prodrugs with different drug binding rates (DBRs) were synthesized through the conjugation of oxidized HES and DOX with a pH-responsive Schiff base bond. The DBRs of HESDOX conjugates were determined to be 1.7, 3.3, and 5.9%, which could be facilely adjusted by the feeding molar amount of DOX. All HESDOX conjugates could spontaneously self-assemble into spherical micellar nanoparticles in phosphate-buffered saline. The hydrodynamic diameter decreased from 73.4 ± 5.3, 63.9 ± 5.5, to 51.9 ± 8.5 nm with the increase of the DBR from 1.7, 3.3, to 5.9%. The DOX release from HESDOX could be accelerated by the decrease of pH and the DBR, attributed to the acid-sensitive Schiff base bond and the loose core, respectively. Furthermore, the HESDOX micelle selectively released DOX in the endosome and/or lysosome after cellular uptake, and exhibited excellent proliferation inhibition toward murine melanoma B16F10 cells in vitro and in vivo. Furthermore, the antitumor efficacy was upregulated by the increase of the DBR, benefiting from the selective acidity-triggered DOX release in tumor cells. These results indicated that HESDOX exhibited great potential in the precise chemotherapy of malignancy.

Physical properties of CO-dark molecular gas traced by C$^+$

Abstract: Context. Neither Hi nor CO emission can reveal a significant quantity of so-called dark gas in the interstellar medium (ISM). It is considered that CO-dark molecular gas (DMG), the molecular gas with no or weak CO emission, dominates dark gas. Determination of physical properties of DMG is critical for understanding ISM evolution. Previous studies of DMG in the Galactic plane are based on assumptions of excitation temperature and volume density. Independent measurements of temperature and volume density are necessary. Aims. We intend to characterize physical properties of DMG in the Galactic plane based on C + data from the Herschel open time key program, namely Galactic Observations of Terahertz C+ (GOT C+) and Hi narrow self-absorption (HINSA) data from international Hi 21 cm Galactic plane surveys. Methods. We identified DMG clouds with HINSA features by comparing Hi, C + , and CO spectra. We derived the Hi excitation temperature and Hi column density through spectral analysis of HINSA features. The Hi volume density was determined by utilizing the on-the-sky dimension of the cold foreground Hi cloud under the assumption of axial symmetry. The column and volume density of H 2 were derived through excitation analysis of C + emission. The derived parameters were then compared with a chemical evolutionary model. Results. We identified 36 DMG clouds with HINSA features. Based on uncertainty analysis, optical depth of Hi τ Hi of 1 is a reasonable value for most clouds. With the assumption of τ Hi = 1, these clouds were characterized by excitation temperatures in a range of 20 K to 92 K with a median value of 55 K and volume densities in the range of 6.2 × 10 1 cm -3 to 1.2 × 10 3 cm -3 with a median value of 2.3 × 10 2 cm -3 . The fraction of DMG column density in the cloud ( f DMG ) decreases with increasing excitation temperature following an empirical relation f DMG =−2.1 × 10 -3 T ex ,( τ Hi = 1) + 1.0. The relation between f DMG and total hydrogen column density N H is given by f DMG = 1.0−3.7 × 10 20 / N H . We divided the clouds into a high extinction group and low extinction group with the dividing threshold being total hydrogen column density N H of 5.0 × 10 21 cm -2 ( A V = 2.7 mag). The values of f DMG in the low extinction group ( A V ≤ 2.7 mag) are consistent with the results of the time-dependent, chemical evolutionary model at the age of ~10 Myr. Our empirical relation cannot be explained by the chemical evolutionary model for clouds in the high extinction group ( A V > 2.7 mag). Compared to clouds in the low extinction group ( A V ≤ 2.7 mag), clouds in the high extinction group ( A V > 2.7 mag) have comparable volume densities but excitation temperatures that are 1.5 times lower. Moreover, CO abundances in clouds of the high extinction group ( A V > 2.7 mag) are 6.6 × 10 2 times smaller than the canonical value in the Milky Way. Conclusions. The molecular gas seems to be the dominate component in these clouds. The high percentage of DMG in clouds of the high extinction group ( A V > 2.7 mag) may support the idea that molecular clouds are forming from pre-existing molecular gas, i.e., a cold gas with a high H 2 content but that contains a little or no CO content.

Gas Kinematics and Star Formation in the Filamentary IRDC G34.43+0.24

Abstract: We performed a multiwavelength study toward infrared dark cloud (IRDC) G34.43+0.24. New maps of 13CO $J$=1-0 and C18}O J=1-0 were obtained from the Purple Mountain Observatory (PMO) 13.7 m radio telescope. At 8 um (Spitzer - IRAC), IRDC G34.43+0.24 appears to be a dark filament extended by 18 arcmin along the north-south direction. Based on the association with the 870 um and C18O J=1-0 emission, we suggest that IRDC G34.43+0.24 should not be 18 arcmin in length, but extend by 34 arcmin. IRDC G34.43+0.24 contains some massive protostars, UC H II regions, and infrared bubbles. The spatial extend of IRDC G34.43+0.24 is about 37 pc assuming a distance of 3.7 kpc. IRDC G34.43+0.24 has a linear mass density of 1.6*10^{3} M_{sun} pc^{-1}, which is roughly consistent with its critical mass to length ratio. The turbulent motion may help stabilizing the filament against the radial collapse. Both infrared bubbles N61 and N62 show a ringlike structure at 8 um. Particularly, N61 has a double-shell structure, which has expanded into IRDC G34.43+0.24. The outer shell is traced by 8 um and 13}CO J=1-0 emission, while the inner shell is traced by 24 um and 20 cm emission. We suggest that the outer shell (9.9*10^{5} yr) is created by the expansion of H II region G34.172+0.175, while the inner shell (4.1-6.3*10^{5} yr) may be produced by the energetic stellar wind of its central massive star. From GLIMPSE I catalog, we selected some Class I sources with an age of 10^{5} yr. These Class I sources are clustered along the filamentary molecular cloud.

Star formation laws in both galactic massive clumps and external galaxies: extensive study with dust coninuum, hcn (4-3), and cs (7-6)

Abstract: We observed 146 Galactic clumps in HCN (4-3) and CS (7-6) with the Atacama Submillimeter Telescope Experiment 10 m telescope. A tight linear relationship between star formation rate and gas mass traced by dust continuum emission was found for both Galactic clumps and the high redshift (z > 1) star forming galaxies (SFGs), indicating a constant gas depletion time of similar to 100 Myr for molecular gas in both Galactic clumps and high z SFGs. However, low z galaxies do not follow this relation and seem to have a longer global gas depletion time. The correlations between total infrared luminosities (L-TIR) and molecular line luminosities (L-mol') of HCN (4-3) and CS (7-6) are tight and sublinear extending down to clumps with L-TIR similar to 10(3) L-circle dot. These correlations become linear when extended to external galaxies. A bimodal behavior in the L-TIR-L-mol' correlations was found for clumps with different dust temperature, luminosity-to-mass ratio, and sigma(line)/sigma(vir). Such bimodal behavior may be due to evolutionary effects. The slopes of L-TIR-L-mol' correlations become more shallow as clumps evolve. We compared our results with lower J transition lines in Wu et al. (2010). The correlations between clump masses and line luminosities are close to linear for low effective excitation density tracers but become sublinear for high effective excitation density tracers for clumps with L-TIR larger than L-TIR similar to 10(4.5) L-circle dot. High effective excitation density tracers cannot linearly trace the total clump masses, leading to a sublinear correlations for both M-clump-L-mol' and L-TIR-L-mol' relations.

Discovery of an extremely wide-angle bipolar outflow in afgl 5142

Abstract: Most bipolar outflows are associated with individual young stellar objects and have small opening angles. Here we report the discovery of an extremely wide-angle (similar to 180 degrees) bipolar outflow ("EWBO") in a cluster forming region AFGL 5142 from low-velocity emission of the HCN (3-2) and HCO+ (3-2) lines. This bipolar outflow is along a north-west to south-east direction with a line of sight flow velocity of about 3 km s(-1) and is spatially connected to the high-velocity jet-like outflows. It seems to be a collection of low-velocity material entrained by the high-velocity outflows due to momentum feedback. The total ejected mass and mass loss rate due to both high-velocity jet-like outflows and the "EWBO" are similar to 24.5 M-circle dot and similar to 1.7 x 10(-3)M(circle dot) yr(-1), respectively. Global collapse of the clump is revealed by the " blue profile" in the HCO+ (1-0) line. A hierarchical network of filaments was identified in NH3 (1, 1) emission. Clear velocity gradients of the order of 10 km s(-1) pc(-1) are found along filaments, indicating gas inflow along the filaments. The sum of the accretion rate along filaments and mass infall rate along the line of sight is similar to 3.1 x 10(-3) M-circle dot yr(-1), which exceeds the total mass loss rate, indicating that the central cluster is probably still gaining mass. The central cluster is highly fragmented and 22 condensations are identified in 1.1 mm continuum emission. The fragmentation process seems to be determined by thermal pressure and turbulence. The magnetic field may not play an important role in fragmentation.

Star formation laws in both Galactic massive clumps and external galaxies: An extensive study with dust continuum, HCN (4-3), and CS (7-6)

Abstract: We observed 146 Galactic clumps in HCN (4-3) and CS (7-6) with the Atacama Submillimeter Telescope Experiment (ASTE) 10-m telescope. A tight linear relationship between star formation rate and gas mass traced by dust continuum emission was found for both Galactic clumps and the high redshift (z>1) star forming galaxies (SFGs), indicating a constant gas depletion time of ~100 Myr for molecular gas in both Galactic clumps and high z SFGs. However, low z galaxies do not follow this relation and seem to have a longer global gas depletion time. The correlations between total infrared luminosities (L_TIR) and molecular line luminosities (L'_mol) of HCN (4-3) and CS (7-6) are tight and sublinear extending down to clumps with LTIR~10^{3} L_sun. These correlations become linear when extended to external galaxies. A bimodal behavior in the LTIR--L'mol correlations was found for clumps with different dust temperature, luminosity-to-mass ratio, and sigmaline/sigmavir. Such bimodal behavior may be due to evolutionary effects. The slopes of LTIR--L'mol correlations become more shallow as clumps evolve. We compared our results with lower J transition lines in wu et al. (2010). The correlations between clump masses and line luminosities are close to linear for low effective excitation density tracers but become sublinear for high effective excitation density tracers for clumps with LTIR larger than LTIR~10^4.5 Lsun. High effective excitation density tracers cannot linearly trace the total clump masses, leading to a sublinear correlations for both Mclump-L'mol and LTIR-L'mol relations.

Enhanced thermoelectric figure of merit in p-type β-Zn4Sb3/Bi0.4Sb1.6Te3 nanocomposites

Abstract: The thermoelectric properties of Bi0.4Sb1.6Te3-based composites incorporated with β-Zn4Sb3 nanoparticles are investigated in the temperature range from 300 K to 500 K. The results show that ∼5% increase in Seebeck coefficient and ∼32% reduction of lattice thermal conductivity at 443 K are concurrently realized in the nanocomposite system with 1.3 vol% of β-Zn4Sb3, which originates from energy filtering effect as well as enhanced phonon scattering at dispersed nanoparticles and phase boundaries, respectively. As a result, the largest figure of merit ZT = 1.43 is achieved at 443 K for the sample with 1.3 vol% of β-Zn4Sb3 nanoinclusions, which is ∼18% larger than that (=1.21) of the Bi0.4Sb1.6Te3 matrix.

Cloud Structure of Galactic OB Cluster Forming Regions from Combining Ground and Space Based Bolometric Observations

Abstract: We have developed an iterative procedure to systematically combine the millimeter and submillimeter images of OB cluster-forming molecular clouds, which were taken by ground based (CSO, JCMT, APEX, IRAM-30m) and space telescopes (Herschel, Planck). For the seven luminous ($L$$>$10$^{6}$ $L_{\odot}$) Galactic OB cluster-forming molecular clouds selected for our analyses, namely W49A, W43-Main, W43-South, W33, G10.6-0.4, G10.2-0.3, G10.3-0.1, we have performed single-component, modified black-body fits to each pixel of the combined (sub)millimeter images, and the Herschel PACS and SPIRE images at shorter wavelengths. The $\sim$10$"$ resolution dust column density and temperature maps of these sources revealed dramatically different morphologies, indicating very different modes of OB cluster-formation, or parent molecular cloud structures in different evolutionary stages. The molecular clouds W49A, W33, and G10.6-0.4 show centrally concentrated massive molecular clumps that are connected with approximately radially orientated molecular gas filaments. The W43-Main and W43-South molecular cloud complexes, which are located at the intersection of the Galactic near 3-kpc (or Scutum) arm and the Galactic bar, show a widely scattered distribution of dense molecular clumps/cores over the observed $\sim$10 pc spatial scale. The relatively evolved sources G10.2-0.3 and G10.3-0.1 appear to be affected by stellar feedback, and show a complicated cloud morphology embedded with abundant dense molecular clumps/cores. We find that with the high angular resolution we achieved, our visual classification of cloud morphology can be linked to the systematically derived statistical quantities (i.e., the enclosed mass profile, the column density probability distribution function, the two-point correlation function of column density, and the probability distribution function of clump/core separations).

l-Cystine-Crosslinked Polypeptide Nanogel as a Reduction-Responsive Excipient for Prostate Cancer Chemotherapy

Abstract: Smart polymer nanogel-assisted drug delivery systems have attracted more and more attention in cancer chemotherapy because of their well-defined morphologies and pleiotropic functions in recent years. In this work, an l-cystine-crosslinked reduction-responsive polypeptide nanogel of methoxy poly(ethylene glycol)-poly(l-phenylalanine-co-l-cystine) (mPEG-P(LP-co-LC)) was employed as a smart excipient for RM-1 prostate cancer (PCa) chemotherapy. Doxorubicin (DOX), as a regular chemotherapy drug, was embedded in the nanogel. The loading nanogel marked as NG/DOX was shown to exhibit glutathione (GSH)-induced swelling and GSH-accelerated DOX release. Subsequently, NG/DOX showed efficient cellular uptake and proliferation inhibition. Furthermore, NG/DOX presented enhanced antitumor efficacy and security in an RM-1 PCa-grafted mouse model in vivo, indicating its great potential for clinical treatment.

Ch as a molecular gas tracer and c-shock tracer across a molecular cloud boundary in taurus

Abstract: We present new observations of all three ground-state transitions of the methylidyne (CH) radical and all four ground-state transitions of the hydroxyl (OH) radical toward a sharp boundary region of the Taurus molecular cloud. These data were analyzed in conjunction with existing CO and dust images. The derived CH abundance is consistent with previous observations of translucent clouds (0.8 <= A(v) <= 2.1 mag). The X(CH)-factor is nearly a constant (1.0 +/- 0.06) x 10(22) cm(-2) K-1 km(-1) s in this extinction range, with less dispersion than that of the more widely used molecular tracers CO and OH. CH turns out be a better tracer of total column density in such an intermediate extinction range than CO or OH. Compared with previous observations, CH is overabundant below 1 mag extinction. Such an overabundance of CH is consistent with the presence of a C-shock. CH has two kinematic components, one of which shifts from 5.3 to 6 km s(-1), while the other stays at 6.8 km s(-1) when moving from outside toward inside of the cloud. These velocity behaviors exactly match previous OH observation. The shifting of the two kinematic components indicates colliding streams or gas flow at the boundary region, which could be the cause of the C-shock.

Self-Targeted Polysaccharide Prodrug Suppresses Orthotopic Hepatoma.

Abstract: Self-targetability is an emerging targeting strategy for polymer nanocarriers with facile preparation and high targeting efficiency An acid-sensitive dextran–doxorubicin prodrug (Dex-g-DOX) has been synthesized and used as a self-targeted drug delivery system for the treatment of orthotopic hepatoma The polysaccharide prodrug exhibits ultraselective accumulation in cancerous liver tissue, acid-sensitive DOX release within cells, and high antitumor efficacy in vitro and in vivo Therefore, Dex-g-DOX demonstrates great potential for chemotherapy of orthotopic hepatoma

Intensity Distribution Function and Statistical Properties of Fast Radio Bursts

Abstract: Fast Radio Bursts (FRBs) are intense radio flashes from the sky that are characterized by millisecond durations and Jansky-level flux densities We carried out a statistical analysis on FRBs discovered Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be $\sim 660\,\rm pc\,cm^{-3}$, supporting their being from cosmological origin Their energy released in radio band spans about two orders of magnitude, with a mean value of $\sim 10^{39}$ ergs More interestingly, although the FRB study is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function For the 16 non-repeating FRBs detected by Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as $dN/dF_{\rm obs} = (41 \pm 13) \times 10^3 \, F_{\rm obs}^{-11\pm02} \; \rm sky^{-1}\,day^{-1}$, where $F_{\rm obs}$ is the observed radio fluence in units of Jy~ms Here the power-law index is significantly flatter than the expected value of 25 for standard candles distributed homogeneously in a flat Euclidean space Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) will be able to detect about 5 FRBs for every 1000 hours of observation time

Observations of solar flares with IRIS and SDO

Abstract: Flare kernels brighten simultaneously in all Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) channels making it difficult to determine their temperature structure. The Interface Region Imaging Spectrograph (IRIS) is able to spectrally resolve Fe xxi emission from cold chromospheric brightenings, so it can be used to infer the amount of Fe xxi emission in the 131 A AIA channel. We use observations of two small solar flares seen by IRIS and SDO to compare the emission measures (EMs) deduced from the IRIS Fe xxi line and the AIA 131 A channel to determine the fraction of Fe xxi emission in flare kernels in the 131 A channel of AIA. Cotemporal and cospatial pseudo-raster AIA images are compared with the IRIS results. We use multi-Gaussian line fitting to separate the blending chromospheric emission so as to derive Fe xxi intensities and Doppler shifts in IRIS spectra. We define loop and kernel regions based on the brightness of the 131 A and 1600 A intensities. In the loop regions the Fe xxi EMs are typically 80% of the 131 A values, and range from 67% to 92%. Much of the scatter is due to small misalignments, but the largest site with low Fe xxi contributions was probably affected by a recent injection of cool plasma into the loop. In flare kernels the contribution of Fe xxi increases from less than 10% at the low-intensity 131 A sites to 40−80% in the brighter kernels. Here the Fe xxi is superimposed on bright chromospheric emission and the Fe xxi line shows blueshifts, sometimes extending up to the edge of the spectral window, 200 km s-1 . The AIA 131 A emission in flare loops is due to Fe xxi emission with a 10−20% contribution from continuum, Fe xxiii, and cooler background plasma emission. In bright flare kernels up to 52% of the 131 A is from cooler plasma. The wide range seen in the kernels is caused by significant structure in the kernels, which is seen as sharp gradients in Fe xxi EM at sites of molecular and transition region emission.

Gas Kinematics and Star Formation in the Filamentary IRDC G34.43+0.24

Abstract: We performed a multiwavelength study toward infrared dark cloud (IRDC) G34.43+0.24. New maps of 13CO $J$=1-0 and C18}O J=1-0 were obtained from the Purple Mountain Observatory (PMO) 13.7 m radio telescope. At 8 um (Spitzer - IRAC), IRDC G34.43+0.24 appears to be a dark filament extended by 18 arcmin along the north-south direction. Based on the association with the 870 um and C18O J=1-0 emission, we suggest that IRDC G34.43+0.24 should not be 18 arcmin in length, but extend by 34 arcmin. IRDC G34.43+0.24 contains some massive protostars, UC H II regions, and infrared bubbles. The spatial extend of IRDC G34.43+0.24 is about 37 pc assuming a distance of 3.7 kpc. IRDC G34.43+0.24 has a linear mass density of 1.6*10^{3} M_{sun} pc^{-1}, which is roughly consistent with its critical mass to length ratio. The turbulent motion may help stabilizing the filament against the radial collapse. Both infrared bubbles N61 and N62 show a ringlike structure at 8 um. Particularly, N61 has a double-shell structure, which has expanded into IRDC G34.43+0.24. The outer shell is traced by 8 um and 13}CO J=1-0 emission, while the inner shell is traced by 24 um and 20 cm emission. We suggest that the outer shell (9.9*10^{5} yr) is created by the expansion of H II region G34.172+0.175, while the inner shell (4.1-6.3*10^{5} yr) may be produced by the energetic stellar wind of its central massive star. From GLIMPSE I catalog, we selected some Class I sources with an age of 10^{5} yr. These Class I sources are clustered along the filamentary molecular cloud.

Stereocomplex-Reinforced PEGylated Polylactide Micelle for Optimized Drug Delivery.

Abstract: The instability of PEGylated polylactide micelles is a challenge for drug delivery. Stereocomplex interaction between racemic polylactide chains with different configurations provides an effective strategy to enhance the stability of micelles as the nanocarriers of drugs. In this work, a stereocomplex micelle (SCM) self-assembled from the amphiphilic triblock copolymers comprising poly(ethylene glycol) (PEG), and dextrorotatory and levorotatory polylactides (PDLA and PLLA) was applied for efficient drug delivery. The spherical SCM showed the smallest scale and the lowest critical micelle concentration (CMC) than the micelles with single components attributed to the stereocomplex interaction between PDLA and PLLA. 10-Hydroxycamptothecin (HCPT) as a model antitumor drug was loaded into micelles. Compared with the loading micelles from individual PDLA and PLLA, the HCPT-loaded SCM exhibited the highest drug loading efficiency (DLE) and the slowest drug release in phosphate-buffered saline (PBS) at pH 7.4, indicating its enhanced stability in circulation. More fascinatingly, the laden SCM was demonstrated to have the highest cellular uptake of HCPT and suppress malignant cells most effectively in comparison to the HCPT-loaded micelles from single copolymer. In summary, the stereocomplex-enhanced PLA–PEG–PLA micelle may be promising for optimized drug delivery in the clinic.

Mesomeric configuration makes polyleucine micelle an optimal nanocarrier.

Abstract: Micelle with mesomeric polyleucine (PDLLeu) core demonstrated the most uniform morphology, the smallest diameter and the highest drug loading capability compared to those with dextrorotatory (PDLeu), levorotatory (PLLeu) and racemic PLeu (PD/LLeu) cores. In addition, the modification with c(RGDfC) endowed the optimal PDLLeu micelle with enhanced intracellular drug release and cytotoxicity, indicating its great potential for targeted drug delivery.

Thermoelectric transport properties of PbTe-based composites incorporated with Cu2Se nano-inclusions

Abstract: Thermoelectric transport properties of Lead telluride (PbTe)-based composites incorporated with Cuprous selenide (Cu2Se) nano-inclusions were investigated from 300 K to 800 K. Here, except for the transition from p-type to n-type conduction that occurs in pristine PbTe at ~530 K due to the difference of mobility between thermally electron and hole at high temperature, another transition from p-type to n-type conduction at 300 K with an increasing proportion of Cu2Se could be due to the donor levels introduced by defects and unsaturated bonds at the interfaces. Moreover, by incorporating a small proportion (5 vol.%) of Cu2Se nanoparticles into the PbTe matrix to form nano-composites, both a reduction (~55%) in lattice thermal conductivity and an enhanced electrical conductivity compared with that of pristine PbTe are obtained, which allows the thermoelectric power factor to reach a larger value (~11.2 μW cm−1 K−2). Consequently, a maximum value ZT = 0.91 is obtained at 760 K in the PbTe-5 vol.% Cu2Se sample.

Dual-encryption based on facilely synthesized supra-(carbon nanodots) with water-induced enhanced luminescence

Abstract: A series of low cost and easily prepared supra-(carbon nanodots (CNDs)) were developed by injecting CND ethanol solutions into toluene under vigorous stirring to induce nano-sized aggregates. Water-jet printing of luminescent patterns and mapping of human sweat pore patterns can be realized on the supra-CND-coated paper. With the application of two kinds of supra-CNDs, dual-encrypted luminescence information was constructed through water-jet printing and hand writing. We found that the low-cost and easily prepared supra-CNDs can be expected to show considerable potential to achieve multi-level encryption in anti-counterfeiting and information security.

CH as a Molecular Gas Tracer and C-Shock Tracer Across a Molecular Cloud Boundary in Taurus

Abstract: We present new observations of all three ground-state transitions of the methylidyne (CH) radical and all four ground-state transitions of the hydroxyl (OH) radical toward a sharp boundary region of the Taurus molecular cloud. These data were analyzed in conjunction with existing CO and dust images. The derived CH abundance is consistent with previous observations of translucent clouds ($0.8\le A_{v} \le 2.1$ mag). The $X({\rm CH})$-factor is nearly a constant at $(1.0\pm0.06)\times 10^{22}$ $\rm {cm^{-2}~K^{-1}~km^{-1}~s}$ in this extinction range, with less dispersion than that of the more widely used molecular tracers CO and OH. CH turns out be a better tracer of total column density in such an intermediate extinction range than CO or OH. Compared with previous observations, CH is overabundant below 1 mag extinction. Such an overabundance of CH is consistent with the presence of a C-shock. CH has two kinematic components, one of which shifts from 5.3 to 6 km s$^{-1}$, while the other stays at 6.8 km s$^{-1}$ when moving from outside toward inside of the cloud. These velocity behaviors exactly match with previous OH observation. The shifting of the two kinematic components indicates colliding streams or gas flow at the boundary region, which could be the cause of the C-shock.

Massive quiescent cores in orion. vi. the internal structures and a candidate of transiting core in ngc 2024 filament

Abstract: We present a multiwavelength observational study of the NGC 2024 filament using infrared to submillimeter continuum and the NH3 (1, 1) and (2, 2) inversion transitions centered on FIR-3, the most massive core therein. FIR-3 is found to have no significant infrared point sources in the Spitzer/IRAC bands. But the NH3 kinetic temperature map shows a peak value at the core center with T-k = 25 K, which is significantly higher than the surrounding level (T-k = 15-19 K). Such internal heating signature without an infrared source suggests an ongoing core collapse possibly at a transition stage from first hydrostatic core (FHSC) to protostar. The eight dense cores in the filament have dust temperatures between 17.5 and 22 K. They are much cooler than the hot ridge (T-d similar to 55 K) around the central heating star IRS-2b. Comparison with a dust heating model suggests that the filament should have a distance of 3-5 pc from IRS-2b. This value is much larger than the spatial extent of the hot ridge, suggesting that the filament is spatially separated from the hot region along the line of sight.