Abstract
In the present study, a method for the synthesis of gelatin-stabilized copper oxide nanoparticles was developed. Synthesis was carried out by direct chemical precipitation. Copper sulfate, ...chloride, and acetate were used as precursors for the copper oxide synthesis. Gelatin was used as a stabilizer. It was found that the formation of monophase copper oxide II only occurred when copper acetate was used as a precursor. Our results showed that particles of the smallest diameter are formed in an aqueous medium (18 ± 6 nm), and those of th largest diameter—in an isobutanol medium (370 ± 131 nm). According to the photon correlation spectroscopy data, copper oxide nanoparticles synthesized in an aqueous medium were highly stable and had a monomodal size distribution with an average hydrodynamic radius of 61 nm. The study of the pH effect on the colloidal stability of copper oxide nanoparticles showed that the sample was stable in the pH range of 6.8 to 11.98. A possible mechanism for the pH influence on the stability of copper oxide nanoparticles is described. The effect of the ionic strength of the solution on the stability of the CuO nanoparticles sol was also studied, and the results showed that Ca
2+
ions had the greatest effect on the sample stability. IR spectroscopy showed that the interaction of CuO nanoparticles with gelatin occurred through the hydroxyl group. It was found that CuO nanoparticles stabilized with gelatin have a fungicidal activity at concentration equivalent 2.5 · 10
−3
mol/L and as a material for food nanopackaging can provide an increase in the shelf life of products on the example of strawberries and tomatoes. We investigated the possibility of using methylcellulose films modified with CuO nanoparticles for packaging and storage of hard cheese “Holland”. The distribution of CuO nanoparticles in the methylcellulose film was uniform. We found that methylcellulose films modified with CuO nanoparticles inhibited the growth and development of QMAFAM, coliforms, yeast and mold in experimental cheese sa mples. Our research has shown that during the cheese storage in thermostat at 35 ± 1 °C for 7 days, CuO nanoparticles migrated to the product from the film. Nevertheless, it is worth noting that the maximum change in the concentration of copper in the experimental samples was only 0.12 µg/mg, which is not a toxic concentration. In general, the small value of migration of CuO nanoparticles confirms the high stability of the developed preparation. Our results indicated that the CuO nanoparticles stabilized with gelatin have a high potential for use in food packaging – both as an independent nanofilm and as part of other packaging materials.
We present a multiwavelength study of the W40 star-forming region using infrared (IR) observations in the UKIRT JHK bands, Spitzer Infrared Array Camera bands, and Herschel PACS bands, 2.12 mu m H ...sub(2) narrowband imaging, and radio continuum observations from GMRT (610 and 1280 MHz), in a field of view (FoV) of ~34' x 40'. Archival Spitzer observations in conjunction with near-IR observations are used to identify 1162 Class II/III and 40 Class I sources in the FoV. The nearest-neighbor stellar surface density analysis shows that the majority of these young stellar objects (YSOs) constitute the embedded cluster centered on the high-mass source IRS 1A South. Radio continuum analysis shows that this region has a blister morphology, with the radio peak coinciding with a protostellar source.
The motion of atoms in a solid always responds to cooling or heating in a way that is consistent with the symmetry of the given space group of the solid to which they belong. When the atoms move, the ...electronic structure of the solid changes, leading to different physical properties. Therefore, the determination of where atoms are and what atoms do is a cornerstone of modern solid-state physics. However, experimental observations of atomic displacements measured as a function of temperature are very rare, because those displacements are, in almost all cases, exceedingly small. Here we show, using a combination of diffraction techniques, that the hexagonal manganites RMnO3 (where R is a rare-earth element) undergo an isostructural transition with exceptionally large atomic displacements: two orders of magnitude larger than those seen in any other magnetic material, resulting in an unusually strong magneto-elastic coupling. We follow the exact atomic displacements of all the atoms in the unit cell as a function of temperature and find consistency with theoretical predictions based on group theories. We argue that this gigantic magneto-elastic coupling in RMnO3 holds the key to the recently observed magneto-electric phenomenon in this intriguing class of materials.
Use of polyacrylate-polyalcohol copolymer (PPC) after endoscopic correction (EC) of vesico-ureteral reflux (VUR) is highly effective but is associated with a higher risk of obstructive complications ...(OC) compared with other implants. We undertook a STROBE compliant retrospective investigation and studied the OC risk factors to increase the practical safety of PPC.Overall, 798 patients (464 58.1% girls and 334 41.9%) boys) from 5 hospitals in whom PPC was routinely used were evaluated retrospectively. The patients were subdivided into 2 groups. Group I consisted of 754 (94.5%) children (449 59.5% girls and 305 40.5% boys) without OC. Median age was 41 months Q1: 18.0; Q3: 81.0. Group II comprised 44 (5.5%) patients (29 65.9% boys and 15 34.1% girls) experiencing OC, and their median age was 21.5 months Q1: 12.0; Q3: 43.0. Clinical and renal ultrasound examinations were carried out 1 day and 1 month after EC, and then every 6 months after EC. At the follow-up examination approximately 6 months after EC, voiding cysto-urethrography (VCUG) was performed. All patients with OC underwent diuretic renography.OC occurred in 44 (5.5%) of 798 children, in some cases as late as 60 months after endoscopic injection of the bulking agent PPC for correction of VUR. Univariate analysis revealed that younger age (P < .001), higher grade of VUR (P < .001), male gender (P < .001), second injection (P = .003), and EC injection using hydrodistension implantation technique (HIT; P < .001) represented significant risk factors. At multivariate analysis, only male gender (P = .0078), younger age (P = .0044), HIT technique (P < .0001), and second injection (P = .04) represented significant risk factors for the occurrence of OC.We identified young age, male gender, high reflux grade, HIT technique, and second endoscopic injections as factors associated with the risk of OC after EC of VUR using PPC as a bulking agent. Thus, patients who have undergone EC with PPC must be monitored sonographically for occurrence of OC for at least 60 months after the intervention.
Formation of tissue-specific transcriptional programs underlies multicellular development, including dorsoventral (DV) patterning of the Drosophila embryo. This involves interactions between ...transcriptional enhancers and promoters in a chromatin context, but how the chromatin landscape influences transcription is not fully understood.
Here we comprehensively resolve differential transcriptional and chromatin states during Drosophila DV patterning. We find that RNA Polymerase II pausing is established at DV promoters prior to zygotic genome activation (ZGA), that pausing persists irrespective of cell fate, but that release into productive elongation is tightly regulated and accompanied by tissue-specific P-TEFb recruitment. DV enhancers acquire distinct tissue-specific chromatin states through CBP-mediated histone acetylation that predict the transcriptional output of target genes, whereas promoter states are more tissue-invariant. Transcriptome-wide inference of burst kinetics in different cell types revealed that while DV genes are generally characterized by a high burst size, either burst size or frequency can differ between tissues.
The data suggest that pausing is established by pioneer transcription factors prior to ZGA and that release from pausing is imparted by enhancer chromatin state to regulate bursting in a tissue-specific manner in the early embryo. Our results uncover how developmental patterning is orchestrated by tissue-specific bursts of transcription from Pol II primed promoters in response to enhancer regulatory cues.
The results of spectral observations in the
GHz frequency range of six objects in the southern sky containing dense cores and associated with regions of formation of massive stars and star clusters ...are presented. The observations were carried out with the MOPRA-22m radio telescope. Within the framework of the local thermodynamic equilibrium (LTE) approximation, the column densities and abundances of the H
13
CN, H
13
CO
+
, HN
13
C, HC
3
N, c-C
3
H
2
, SiO, CH
3
C
2
H and CH
3
CN molecules were calculated. Estimates of kinetic temperatures (
K), sizes of emission regions (
pc) and virial masses (
) were obtained. The linewidths in the three cores decrease with increasing distance from the center. In four cores, asymmetry in the profiles of the optically thick lines HCO
+
(1–0) and HCN(1–0) is observed, indicating the presence of systematic motions along the line of sight. In two cases, the asymmetry can be caused by contraction of gas. The model spectral maps of HCO
+
(1–0) and H
13
CO
+
(1–0), obtained within the framework of the non-LTE spherically symmetric model, were fitted into the observed ones. The radial profiles of density (
), turbulent velocity (
), and contraction velocity (
) in the G268.42–0.85 core have been calculated. The contraction velocity profile differs from that expected both in the case of free fall of gas onto a protostar (
), and in the case of global core collapse (contraction velocity does not depend on distance). A discussion of the obtained results is provided.
III–V planar semiconductor heterostructures based on GaPN alloy with a nitrogen concentration up to 2.12% were grown on Si(001) by plasma assisted molecular beam epitaxy. Dependence of nitrogen ...incorporation on the growth conditions and its effect on the crystal structure were investigated via analysis of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy data. Continuous redshift and a substantial increase in intensity of the photoluminescence emission spectra were observed upon increase of nitrogen content. The effect of antiphase disorder in GaP buffer on the GaPN epilayer properties was studied. It was found that antiphase boundaries, protruding from the GaP/Si to the GaPN/GaP heterointerface, change their orientation and self-annihilate in the dilute nitride layer even with a low (0.5%) nitrogen content.
Heterostructures with strongly-coupled multiple quantum wells, such as super-multiperiod superlattices with high perfection, may contain hundreds of layers, whose thicknesses can vary by orders of ...magnitude. The proposed method of characterization, consisting of the matched application of high-resolution X-ray diffractometry and reflectometry, makes it possible to study super-multiperiod structures of various types, including those with long periods and thin layers, and with high accuracy to determine the thicknesses of layers and roughness/diffuseness of boundaries. The difference between the expected and resulting thicknesses of the layers was 2–7% and 1–3% for the type I (InAs/GaAs) and type II (GaAs/Al
0.3
Ga
0.7
As) samples, respectively. Both types of structures are characterized by sharp interfaces with the RMS width of the transition layers of the order of several Å. Based on the best solution of inverse scattering problems, it is possible to determine with high accuracy both the morphology of the layers and their composition. That can be considered as the first step in the analysis of structures with a very large number of periods.
Polycrystalline orthophosphates LiNi
1−
x
Co
x
PO
4
(
x
= 0, 0.1, 0.2, 0.3, 0.4, and 0.5) have been prepared by the glycerol-nitrate synthesis method and used to study by the scanning electron ...microscopy, X-ray fluorescence analysis, X-rays diffraction and Raman scattering. All the LiNi
1−
x
Co
x
PO
4
polycrystalline samples contain particles having average crystallite size of less than 10 μm. According to X-ray fluorescence analysis the cobalt content in the LiNi
1−
x
Co
x
PO
4
samples does not exceed 1 at% comparing to a nominal concentration. In LiNi
1−
x
Co
x
PO
4
(
x
= 0–0.5) doping with cobalt at the nickel position leads to the increase in lattice constants of the olivine crystal structure (
Pnma
space group). The deformation vibrations in the LiNi
1−
x
Co
x
PO
4
crystals were observed in two types of vibrations of PO
4
deformations such as
ν
2
(437.7 cm
−1
) and
ν
4
(582.0 cm
−1
, 591.1 cm
−1
, and 641.2 cm
−1
). Two peaks observed around 400–500 cm
−1
range correspond to NiO
6
or CoO
6
and PO
4
bending (
ν
2
) deformation. Peaks observed around 585 cm
−1
and 635 cm
−1
, correspond to LiO
6
and PO
4
bending (
ν
4
) deformation, respectively. As the concentration of dopant (Co ions) increases, the A
g
mode is gradually shifting toward higher wavenumber (949–950 cm
−1
). Changes in the wavenumber and intensity of the peak corresponding to the dopant element reveal that the dopant ions are occupying corresponding host lattice positions. The P–O3 bond length increased up to
x
= 0.2 and then decreased without a noticeable change in the crystal structure.
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