The China Academy of Space Technology (CAST) designs and builds a new world-class Assembly, Integration and Test Center (AITC) at Tianjin, China. Modal, vibration and acoustic test facilities are ...built to support the future environmental testing needs of China space station program. The Reverberation Acoustic Test Facility (RATF) is about 4000 m
3
in volume and can achieved an empty chamber acoustic overall sound pressure level (OASPL) higher than 156 dB. It is the largest acoustic facility in Asia. Beijing Institute of spacecraft Environment Engineering (BISEE) started its design and construction work from 2012 and put it into use at October of 2015. The RATF will provide an efficient support for environment testing needs of China and world’s space program in the future.
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•Thermodynamic properties of KBr in PEG 4000 + H2O were studied at (288.2, 298.2, and 308.2) K.•Experimental data were fitted to the extended Debye-Hückel and Pitzer models.•Good ...agreement between experimental and correlated data was obtained by both models.•Activity coefficients, the standard free energy of transference, and primary hydration number were reported.
The goal of this research is to evaluate the mean ion activity coefficients (γ±) of the mixtures containing KBr + PEG 4000 + H2O (PEG stands for poly(ethylene glycol)) as well as some other thermodynamic quantities including solvent osmotic coefficients (φ), excess Gibbs energies (GE), standard Gibbs energies of transference (ΔGt0), and primary hydration number (nhydr). The experiment was employed by potentiometric measurement using the cell with two ion-selective electrodes (abbreviated as ISE) at (288.2, 298.2, and 308.2) K, and the mass fraction of PEG 4000 ranged from w = (0 to 0.20) with an increment of 0.05. The type of the cell is as follows:
K–ISE | KBr (m), PEG 4000 (w), H2O (1-w) | Br–ISE.
Nernst's equation was used to combine the Debye-Hückel and Pitzer models with potentiometric values. Pitzer ion interaction parameters (β0, β1, and Cφ) and Debye-Hückel model parameter (a) were evaluated. Moreover, the Bjerrum parameter (q) was calculated.
We utilize Kepler data to study the precision differential photometric variability of solar-type and cooler stars at different timescales, ranging from half an hour to three months. We define a ...diagnostic that characterizes the median differential intensity change between data bins of a given timescale. We apply the same diagnostics to Solar and Heliospheric Observatory data that has been rendered comparable to Kepler. The Sun exhibits similar photometric variability on all timescales as comparable solar-type stars in the Kepler field. The previously defined photometric "range" serves as our activity proxy (driven by starspot coverage). We revisit the fraction of comparable stars in the Kepler field that are more active than the Sun. The exact active fraction depends on what is meant by "more active than the Sun" and on the magnitude limit of the sample of stars considered. This active fraction is between a quarter and a third (depending on the timescale). We argue that a reliable result requires timescales of half a day or longer and stars brighter than M sub(Kep) of 14, otherwise non-stellar noise distorts it. We also analyze main sequence stars grouped by temperature from 6500 to 3500 K. As one moves to cooler stars, the active fraction of stars becomes steadily larger (greater than 90% for early M dwarfs). The Sun is a good photometric model at all timescales for those cooler stars that have long-term variability within the span of solar variability.
Letrozole (LZ) is an aromatase inhibitor, which inhibits the formation of estrogens from androgens. Nanoemulsion is a liquid emulsion formulation utilized to increase solubility, bioavailability, and ...drug delivery to cancer cells. This study aims to improve LZ oral delivery through formulating solid nanoemulsion (SNE). Peppermint oil, tween 80, and transcutol P were used as an oil, surfactant, and co-surfactant, respectively. The optimized nanoemulsion (NE-3) was then incorporated into solid polyethylene glycol (PEG) to formulate (SNE). The optimized (NE-3), SNE-2, and the available marketed tablet have been compared. The optimized (NE-3) was selected according to specific parameters of optimum small nano-size 80 nm, PDI of 0.181, the zeta potential of-98.2, high transmittance (99.78%), optimum pH (5.6), a high percent of LZ content (99.03 ± 1.90), the relatively low viscosity of 60.2 mPa.s, and a rapid release of LZ within 30 min. NE-3 was selected to be formulated as SNE. LZ's best release rate was 80% in 5 min with a content homogeneity of 99.85 ± 0.04 for SNE-2. Zero-order kinetics is determined to have the greatest R2 values. Field emission scanning electron microscopy (FE-SEM) detected that SNE-2 was (36.75–96.64 nm) with a spherical form and no adhesion or aggregation. FT-IR showed no significant variations in position and shape of the absorption peaks between the pure drug and optimal formulation diagrams. This novel nanoemulsion technology aids in improving the solubility of poorly water-soluble drugs, particularly the SNE delivery method, which has a higher in-vitro release rate and expiration date of LZ than others.
Objective: The goal of this study was to use a solid dispersion approach to improve the aqueous solubility and dissolution rate of Telmisartan.
Methods: Design of experiment trials was conducted ...following a central composite design with different combinations of polymers and stirrer rpm and the selected responses (drug release, entrapment efficiency) were determined. The selected optimized formulation was characterized by Fourier-transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, and X-ray diffraction, which reflected the changes that occurred in API and excipients after conversion in to the formulation.
Results: In the design of experiments, central composite design was implemented and it was observed that polymers concentration (polyvinyl pyrrolidine K25, polyethylene glycol 4000) and stirrer rpm were having a significant impact on the responses (drug release, entrapment efficiency), and variables were having p-value<0.05 which reflected the significant impact. The results of stability study showed a significant no decrease in drug assay values, which reflected the stability behavior of the formulation. The results of comparative dissolution studies revealed that the optimized formulation have improved the drug solubility and dissolution rate.
Conclusion: It can be concluded that optimized telmisartan-loaded solid dispersion improved the solubility and dissolution rate of Telmisartan. The optimized formulation was having release>85% release within 30 min. Further, the stability of the formulation was also assessed under the accelerated condition as per ICH which reflected their stability. So, this approach can be employed for improving dissolution rate of other BCS II class drugs.
ION-BY-ION COOLING EFFICIENCIES Gnat, Orly; Ferland, Gary J
The Astrophysical journal. Supplement series,
03/2012, Letnik:
199, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We present ion-by-ion cooling efficiencies for low-density gas. We use Cloudy (version 10.00) to estimate the cooling efficiencies for each ion of the first 30 elements (H-Zn) individually. We ...present results for gas temperatures between 10 super(4) and 10 super(8) K, assuming low densities and optically thin conditions. When nonequilibrium ionization plays a significant role the ionization states deviate from those that obtain in collisional ionization equilibrium (CIE), and the local cooling efficiency at any given temperature depends on specific nonequilibrium ion fractions. The results presented here allow for an efficient estimate of the total cooling efficiency for any ionic composition. We also list the elemental cooling efficiencies assuming CIE conditions. These can be used to construct CIE cooling efficiencies for non-solar abundance ratios or to estimate the cooling due to elements not included in any nonequilibrium computation. All the computational results are listed in convenient online tables.
We point out that the existence of metastable, tau>10(3) s, negatively charged electroweak-scale particles (X-) alters the predictions for lithium and other primordial elemental abundances for A>4 ...via the formation of bound states with nuclei during big bang nucleosynthesis. In particular, we show that the bound states of X- with helium, formed at temperatures of about T=10(8) K, lead to the catalytic enhancement of 6Li production, which is 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X- does not lead to large nonthermal big bang nucleosynthesis effects, this directly translates to the level of sensitivity to the number density of long-lived X- particles (tau>10(5) s) relative to entropy of nX-/s less, approximately <3x10(-17), which is one of the most stringent probes of electroweak scale remnants known to date.
In the present work, PEG4000 as a hydrophilic polymer was conjugated to the surface of graphene oxide (GO) for effective drug loading and targeting release of doxorubicin. The synthesized nanohybrid ...was characterized with scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD) and Fourier-transformed infrared spectroscopy (FTIR). Doxorubicin as an anticancer drug was immobilized on the nanohybrid surface, and the release profile at two diverse pH besides the MTT assay was investigated. The IC
50
value for the nanohybrid obtained was 0.31 μg/mL. In this work, PEG4000 as a biocompatible polymer grafted on the GO surface to increase the biodispersibility of the drug carrier in a biological environment, but it is the first report of PEG 4000-GO nanohybrid-based drug carrier.
Natural lignocellulose is used as raw material to produce chemicals through biological transformation. The accessibility of cellulase to substrate was also one of the limiting factors of industrial ...production. Polyethylene glycol (PEG) can be used as additive in enzymatic hydrolysis of lignocellulose. In this study, enzymatic activity on simultaneous or non-simultaneous addition of PEG 4000 was investigated, and the partly delignified rice straw, the rice straw and filter paper were used as substrates, respectively. Enzyme activity was characterized by reducing sugar concentration in supernatant which was quantified through 3,5-dinitrosalicylic acid (DNS) method. Addition of PEG has been proven to facilitate enzymatic hydrolysis of lignocellulosic materials. Furthermore, PEG had the positive effect on hydrolytic enzyme activity of pure cellulose materials without lignin. Changes in lignocellulose materials have been observed by inverted microscope and Scanning electron microscope (SEM), and no chemical changes were shown by Fourier transform infrared spectroscopy (FTIR). The promotion of PEG on enzymatic hydrolysis of pure cellulose materials may be due to its loose physical structure and similar phenomenon in natural lignin materials. PEG loosens the physical structure of lignocellulose, thus facilitating enzymatic hydrolysis. This may be a new idea to optimize the lignocellulosic enzymatic hydrolysis process.
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