ABSTRACT We report the multi-epoch detections of water ice in 2.8-4.2 spectra of two Herbig Ae stars, PDS 144N (A2 IVe) and PDS 453 (F2 Ve), which have an edge-on circumstellar disk. The detected ...water ice absorption is found to originate from their protoplanetary disks. The spectra show a relatively shallow absorption of water ice of around 3.1 for both objects. The optical depths of the water ice absorption are ∼0.1 and ∼0.2 for PDS 144N and PDS 453, respectively. Compared to the water ice previously detected in low-mass young stellar objects with an edge-on disk with a similar inclination angle, these optical depths are significantly lower. It suggests that stronger UV radiation from the central stars effectively decreases the water ice abundance around the Herbig Ae stars through photodesorption. The water ice absorption in PDS 453 shows a possible variation of the feature among the six observing epochs. This variation could be due to a change of absorption materials passing through our line of sight to the central star. The overall profile of the water ice absorption in PDS 453 is quite similar to the absorption previously reported in the edge-on disk object d216-0939, and this unique profile may be seen only at a high inclination angle in the range of 76°-80°.
pH-sensitive amphiphilic diblock polyphosphoesters containing lactic acid units were synthesized by multistep one-pot polycondensation reactions. They comprise acid-labile P(O)-O-C and C(O)-O-C ...bonds, the cleavage of which depends on the pH of the medium. The structure of these copolymers was characterized by
H,
C {H},
P NMR, and size exclusion chromatography (SEC). The newly synthesized polymers self-assembled into the micellar structure in an aqueous solution. The effects of the molecular weight of the copolymer and the length of the hydrophobic chain on micelle formation and stabilityand micelle size were studied via dynamic light scattering (DLS). Drug loading and encapsulation efficiency tests using doxorubicin revealed that hydrophobic drugs can be delivered by copolymers. It was established that the molecular weight of the copolymer, length of the hydrophobic chain and content of lactate units affects the size of the micelles, drug loading, and efficiency of encapsulation. A copolymer with 10.7% lactate content has drug loading (3.2 ± 0.3) and efficiency of encapsulation (57.4 ± 3.2), compared to the same copolymer with 41.8% lactate content (1.63%) and (45.8%), respectively. It was demonstrated that the polyalkylpoly(ethylene glycol) phosphate-
-alkylpoly(ethylene glycol)lactate phosphate DOX system has a pH-sensitive response capability in the result in which DOX was selectively accumulated into the tumor, where pH is acidic. The results obtained indicate that amphiphilic diblock polyphosphoesters have potential as drug carriers.
Abstract
We report unique two-phase anisotropy in the tunnel magnetoresistance (TMR) of a GaMnAs-based magnetic tunnel junction, obtained by investigating the magnetic-field-direction dependence with ...various applied bias voltages. The TMR shows two-fold symmetry about the
1
¯
10
axis at a low bias voltage, while at higher bias voltages, it shows four-fold symmetry about the 〈100〉 axis in the large magnetic field
H
region. Considering modified Jullière’s model and multiple bands with different anisotropic features, we can well reproduce the experimental TMR characteristics. Our results will lead to novel functionalities using TMRs with different symmetries in multi-orbital materials.
The presence of radionuclides at five water purification plants was investigated after an explosion at a nuclear power plant hit by the Great East Japan Earthquake on 11 March 2011. Radioactive ...iodine (131I) and cesium (134Cs and 137Cs) were detected in raw water in Fukushima and neighboring prefectures. 131I was not removed by coagulation–flocculation–sedimentation. 131I was removed by granular activated carbon (GAC) and powdered activated carbon (PAC) at a level of about 30%–40%, although 131I was not removed in some cases. This was also confirmed by laboratory-scale experiments using PAC. The removal percentages of 131I in river and pond waters by 25 mg dry/L of PAC increased from 36% to 59% and from 41% to 48%, respectively, with chlorine dosing before PAC. 134Cs and 137Cs were effectively removed by coagulation at both a water purification plant and in laboratory-scale experiments when turbidity was relatively high. In contrast, 134Cs and 137Cs in pond water with low turbidity were not removed by coagulation. This was because 134Cs and 137Cs in river water were present mainly in particulate form, while in pond water they were present mainly as cesium ions (134Cs+ and 137Cs+). However, the removal of 134Cs and 137Cs in pond water by coagulation increased markedly when 134Cs and 137Cs were mixed with sediment 24 h before coagulation.
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► Profiles of 131I, 134Cs and 137Cs at water purification plants were investigated. ► At laboratory-scale experiments, removal of 131I, 134Cs and 137Cs was examined. ► 131I removal in waters was increased by a combination of chlorine and PAC. ► Removal of 134Cs and 137Cs in water with high turbidity by coagulation was high.
Multistep one-pot polycondensation reactions synthesized amphiphilic diblock polyphosphoesters containing lactic acid units in the polymer backbone. At the first step was synthesized ...polypoly(ethylene glycol) H-phosphonate-
-poly(ethylene glycol)lactate H-phosphonate was converted through one pot oxidation into polyalkylpoly(ethylene glycol) phosphate-
-alkylpoly(ethylene glycol)lactate phosphates. They were characterized by
H,
C {H},
P NMR, and size exclusion chromatography (SEC). The effects of the polymer composition on micelle formation and stability, and micelle size were studied via dynamic light scattering (DLS). The hydrophilic/hydrophobic balance of these polymers can be controlled by changing the chain lengths of hydrophobic alcohols. Drug loading and encapsulation efficiency tests using Sudan III and doxorubicin revealed that hydrophobic substances can be incorporated inside the hydrophobic core of polymer micelles. The micelle size was 72-108 nm when encapsulating Sudan III and 89-116 nm when encapsulating doxorubicin. Loading capacity and encapsulation efficiency depend on the length of alkyl side chains. Changing the alkyl side chain from 8 to 16 carbon atoms increased micelle-encapsulated Sudan III and doxorubicin by 1.6- and 1.1-fold, respectively. The results obtained indicate that these diblock copolymers have the potential as drug carriers.
Purpose of the present work was to study
in vitro permeation of gold nanoparticles (NPs) through isolated rat skin and intestine. Another objective was to see the effect of particle size on ...permeation of the gold NP.
Gold NP of 15
nm, 102
nm and 198
nm were synthesized and used for study. Franz diffusion cells were used to evaluate permeation of gold NP from rat skin whereas ‘intestinal sac’ method was used for assessing intestinal permeation. Number density of gold NP was analyzed by UV–vis spectroscopy whereas amount of gold permeated was measured by ICP mass spectrometry. The absorption and localization of gold NP through rat skin was studied by TEM. Qualitative analysis of gold inside of the rat skin was performed by energy dispersive X-ray spectroscopy (EDS).
Gold NP showed negative zeta potential. UV–vis absorption spectra of 15
nm, 102
nm and 198
nm gold NP showed
λ
max at 520
nm, 535
nm and 577
nm, respectively. SEM study revealed spherical morphology of NP. Gold NP showed size dependent permeation through rat skin and intestine. 15
nm gold NP showed higher permeation compared to 102
nm and 198
nm gold NP. Interestingly, 102
nm and 198
nm gold NP showed lag time of 3
h and 6
h in case of rat skin only. As the size of the gold NP increased, permeability coefficient and diffusion coefficient was found to be decreased. The permeation of gold NP through intestine was higher than that of skin. TEM study of rat skin revealed accumulation of smaller size gold NP in deeper region of skin whereas larger particles were observed mainly in epidermis and dermis. Presence of gold inside of rat skin was confirmed by EDS.
Gold NP would be an interesting carrier for transdermal as well as for oral delivery. The study demonstrated initial proof of concept of percutaneous permeation of smaller size gold particles.
Using a novel strategy, amphiphilic polyphosphoesters based on poly(oxyethylene H-phosphonate)s (POEHP) with different poly(ethylene glycol) segment lengths and aliphatic alcohols with various alkyl ...chain lengths were synthesized using polycondensation reactions. They were characterized by 1H NMR, 13C {H} NMR 31P NMR, IR, and size exclusion chromatography (SEC). The effects of the polymer structure on micelle formation and stability, micelle size, and critical micelle temperature were studied via dynamic light scattering (DLS). The hydrophilic/hydrophobic balance of these polymers can be controlled by changing the chain lengths of hydrophilic PEG and hydrophobic alcohols. A solubilizing test, using Sudan III, revealed that hydrophobic substances can be incorporated inside the hydrophobic core of polymer associates. Loading capacity depends on the length of alkyl side chains. The results obtained indicate that these structurally flexible polymers have the potential as drug carriers.
In this study, we analyzed the properties of amphiphilic alkyldi(methoxy poly(ethylene glycol) (MePEG)350-lactate) phosphates based on ethyl lactate, the monomethyl ether of poly(ethylene glycol)350, ...and alkyldichloro phosphates. Interestingly, these triesters combine two biodegradable bonds, -P(O)-O-C and -C(O)-O-C-, and include hydrophilic (MePEG350-lactate) and hydrophobic (R-aliphatic chain of alcohols) moieties. The properties of these esters resemble those of phospholipids. After being placed in an aqueous solution, they self-assembled. We also determined the effects of ester composition on micelle formation, stability, and size using dynamic light scattering. Solubilization tests using Sudan III or doxorubicin hydrochloride (Dox·HCl) revealed that they could be incorporated into the hydrophobic cores of dodecyl di(MePEG350-lactate) phosphate and hexadecyl di(MePEG350-lactate) phosphate. Notably, dodecyl di(MePEG350-lactate) phosphate was stable for five days, whereas hexadecyl di(MePEG350-lactate) phosphate was stable for seven days in phosphate-buffered saline. Moreover, Dox·HCl release rates from the micelles were approximately 30-40, 70-80, and 90-100% after 1, 5, and 28 d, respectively.
Certain combinations of acidic and basic drugs can cause significant changes in physicochemical properties through the formation of ionic liquids, eutectic mixtures, or deep eutectic solvents. In ...particular, combining indomethacin and lidocaine is known to result in apparent increases in both the partition coefficients (hydrophobicity) and aqueous solubilities (hydrophilicity). The physicochemical interactions between drugs change the water solubility of the drugs and affect the bio-availability of active pharmaceutical ingredients. Therefore, we need to clarify the mechanism of changes of water solubility of drugs through the physicochemical interactions. In the present study, we identified a thermodynamic factor that regulates the dissolution of a basic drug, in the presence of various acidic nonsteroidal anti-inflammatory drugs. The results demonstrated that enthalpy–entropy compensation plays a key role in the dissolution of drug mixtures and that relevant thermodynamic conditions should be considered.
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