Phenylboronic acid-diol crosslinked 6-<i>O</i>-vinylazeloyl-d-galactose nanocarriers for insulin delivery

A new block polymer named poly 3-acrylamidophenylboronic acid-b-6-O–vinylazeloyl-d-galactose (p(AAPBA-b-OVZG)) was prepared using 3-acrylamidophenylboronic acid (AAPBA) and 6-O-vinylazeloyl-D-galactose (OVZG) via a two-step procedure involving S-1-dodecyl-S-(α', α'-dimethyl-α″-acetic acid) trithiocarbonate (DDATC) as chain transfer agent, 2,2-azobisisobutyronitrile (AIBN) as initiator and dimethyl formamide (DMF) as solvent. The structures of the polymer were examined by Fourier transform infrared spectroscopy (FT-IR) and 1H NMR and the thermal stability was determined by thermal gravimetric analysis (TG/DTG). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were utilized to evaluate the morphology and properties of the p(AAPBA-b-OVZG) nanoparticles. The cell toxicity, animal toxicity and therapeutic efficacy were also investigated. The results indicate the p(AAPBA-b-OVZG) was successfully synthesized and had excellent thermal stability. Moreover, the p(AAPBA-b-OVZG) nanoparticles were submicron in size and glucose-sensitive in phosphate-buffered saline (PBS). In addition, insulin as a model drug had a high encapsulation efficiency and loading capacity and the release of insulin was increased at higher glucose levels. Furthermore, the nanoparticles showed a low-toxicity in cell and animal studies and they were effective at decreasing blood glucose levels of mice over 96 h. These p(AAPBA-b-OVZG) nanoparticles show promise for applications in diabetes treatment using insulin or other hypoglycemic proteins

Protostellar Accretion Flows Destabilized by Magnetic Flux Redistribution

Magnetic flux redistribution lies at the heart of the problem of star formation in dense cores of molecular clouds that are magnetized to a realistic level. If all of the magnetic flux of a typical core were to be dragged into the central star, the stellar field strength would be orders of magnitude higher than the observed values. This well-known "magnetic flux problem" can in principle be resolved through non-ideal MHD effects. Two dimensional (axisymmetric) calculations have shown that ambipolar diffusion, in particular, can transport magnetic flux outward relative to matter, allowing material to enter the central object without dragging the field lines along. We show through simulations that such axisymmetric protostellar accretion flows are unstable in three dimensions to magnetic interchange instability in the azimuthal direction. The instability is driven by the magnetic flux redistributed from the matter that enters the central object. It typically starts to develop during the transition from the prestellar phase of star formation to the protostellar mass accretion phase. In the latter phase, the magnetic flux is transported outward mainly through advection, by strongly magnetized low-density regions that expand against the collapsing inflow. The tussle between the gravity-driven infall and magnetically driven expansion leads to a filamentary inner accretion flow, more disordered than previously pictured. The efficient outward transport of magnetic flux by advection lowers the field strength at small radii, making the magnetic braking less efficient and the formation of rotationally supported disks easier in principle. However, we find no evidence for such disks in any of our rotating collapse simulations. We conclude that the inner protostellar accretion flow is shaped to a large extent by this magnetic interchange instability. How disks form in such an environment is unclear.Comment: 14 pages, 8 figures, submitted to Ap

The absence of jets in cataclysmic variable stars

We show that the recently developed thermal model which successfully describes how jets are launched by young stellar objects, when applied to system containing disk-accreting white dwarfs naturally explain the otherwise surprising absence of jets in cataclysmic variable stars. Our main argument uses the crucial element of the thermal model, namely that the accreted material is strongly shocked due to large gradients of physical quantities in the boundary layer, and then cools on a time scale longer than its ejection time from the disk. In our scenario the magnetic fields are weak, and serve only to recollimate the outflow at large distances from the source, or to initiate the shock, but not as a jet-driving agent. Using two criteria in that model, for the shock formation and for the ejection of mass, we find the mass accretion rate above which jets could be blown from accretion disks around young stellar objects and white dwarfs. We find that these accretion mass rates are ~10^{-7} Mo/yr, and ~10^{-6} Mo/yr for young stellar objects and white dwarfs respectively. Considering the uncertainties of the model, these limits could overestimate the critical value by a factor of ~10.Comment: Submitted to Astronomy and Astrophysic

EXPERIMENTAL STUDY OF TWO LARGE-SCALE MODELS’ SEAKEEPING PERFORMANCE IN COASTAL WAVES

Actual sea waves and vessel motion are an unsteady nonlinear random process. The currently adopted test to simulate wave impact of vessel models in tank can\u27t fully reveal the impact of real sea waves on vessel swing motion. In this paper the buoy wave height meter is adopted to carry out measurements and analyses of the coastal wave environment. The correlation between the coastal wave spectra and the ocean wave spectra is analyzed. The test system is established for remote control and telemetry self-propelled vessel models suitable for the experiment conducted in the coastal areas. The seakeeping performance test is conducted for the same tonnage of round bilge vessel model and the deep-V hybrid monohull of large-scale vessel model under the coastal wave conditions. The experimental results are compared with the test results of small-scale vessel model in the towing tank. The experimental results show that the seakeeping performance of the deep-V hybrid monohull is improved by a wide margin in contrast to that of the round bilge model, and there is a marked difference between the motion characteristics of large-scale vessel models in the coastal wave environment and that of small-scale vessel models in tank

EVALUATION OF WIND AND WAVE ENVIRONMENT ADAPTABILITY OF SHIPS

The environment adaptability especially integrated sailing performance in rough sea of ships is very important. In this paper the evaluation index system and method of wind and wave environment adaptability were proposed. Then the relative importance of the given indices was analyzed, and the weighting coefficients of the indices were given by estimation matrixes. Besides this the evaluation equation was built. And the AHP method and the method based on fuzzy theory were used for evaluating the environment adaptability of a hybrid monohull and a round bilge monohull. Furthermore, the effect of different models and weighting coefficients given by different matrixes for evaluation results were analyzed. The research indicated that the choice of evaluating parameters had great influence on the evaluation results, and the weighting coefficients were the difficult point but critical point for environment adaptability evaluation of ships