Structural and Magnetic Characteristics of Gadolinium Manganite Modified with Barium Gd0.9Ba0.1MnO3

Journal of Superconductivity and Novel Magnetism - The synthesis conditions for the gadolinium manganite doped with barium (x = 0.1) are determined. The sequence and typical features of phase...     

Adsorption of β-glucuronidase and estrogens on pectin/lignin hydrogel particles

The objective of this study was to generate supramolecular complexes of pectin and lignin with properties necessary to interrupt the enterohepatic circulation (EHC) of estrogens. Three types of pectin hydrogel particles were prepared from citrus pectin (PHP), citrus pectin/wheat lignin (PL_WHP), or citrus pectin/oak lignin (PL_OHP). The surface of PHP was smooth, whereas the surface of PL_WHP had irregularly arranged structures and PL_OHP contained pores. PHP actively adsorbed microbial β-glucuronidase and moderately adsorbed estrogens. PL_WHP had moderate and PL_OHP high affinity for estrogens. Thus, PL_OHP meets the requirements of a complex capable of interrupting the EHC of estrogens.     

Subchronic Toxicity of Copper Oxide Nanoparticles and Its Attenuation with the Help of a Combination of Bioprotectors

In the copper metallurgy workplace air is polluted with condensation aerosols, which a significant fraction of is presented by copper oxide particles <100 nm. In the scientific literature, there is a lack of their in vivo toxicity characterization and virtually no attempts of enhancing organism’s resistance to their impact. A stable suspension of copper oxide particles with mean (±SD) diameter 20 ± 10 nm was prepared by laser ablation of pure copper in water. It was being injected intraperitoneally to rats at a dose of 10 mg/kg (0.5 mg per mL of deionized water) three times a week up to 19 injections. In parallel, another group of rats was so injected with the same suspension against the background of oral administration of a “bio-protective complex” (BPC) comprising pectin, a multivitamin-multimineral preparation, some amino acids and fish oil rich in ω-3 PUFA. After the termination of injections, many functional and biochemical indices for the organism’s status, as well as pathological changes of liver, spleen, kidneys, and brain microscopic structure were evaluated for signs of toxicity. In the same organs we have measured accumulation of copper while their cells were used for performing the Random Amplification of Polymorphic DNA (RAPD) test for DNA fragmentation. The same features were assessed in control rats infected intraperitoneally with water with or without administration of the BPC. The copper oxide nanoparticles proved adversely bio-active in all respects considered in this study, their active in vivo solubilization in biological fluids playing presumably an important role in both toxicokinetics and toxicodynamics. The BPC proposed and tested by us attenuated systemic and target organs toxicity, as well as genotoxicity of this substance. Judging by experimental data obtained in this investigation, occupational exposures to nano-scale copper oxide particles can present a significant health risk while the further search for its management with the help of innocuous bioprotectors seems to be justified.     

Reversible Switching of Block Copolymer Nanopatterns by Orthogonal Electric Fields

It is demonstrated that the orientation of striped patterns can be reversibly switched between two perpendicular in‐plane orientations upon exposure to electric fields. The results on thin films of symmetric polystyrene‐block‐poly(2‐vinyl pyridine) polymer in the intermediate segregation regime disclose two types of reorientation mechanisms from perpendicular to parallel relative to the electric field orientation. Domains orient via grain rotation and via formation of defects such as stretched undulations and temporal phase transitions. The contribution of additional fields to the structural evolution is also addressed to elucidate the generality of the observed phenomena. In particular solvent effects are considered. This study reveals the stabilization of the meta‐stable in‐plane oriented lamella due to sequential swelling and quenching of the film. Further, the reorientation behavior of lamella domains blended with selective nanoparticles is addressed, which affect the interfacial tensions of the blocks and hence introduce another internal field to the studied system. Switching the orientation of aligned block copolymer patterns between two orthogonal directions may open new applications of nanomaterials as switchable electric nanowires or optical gratings.     

Composites “binary salts in porous matrix” for adsorption heat transformation

A family of Composites “Salt inside Porous Matrix” (CSPM) has been considered as promising for adsorption heat transformation (AHT) due to their high sorption capacity, steep sorption isobars and opportunity to harmonize CSPM properties with boundary conditions of the AHT cycle. In this communication, we extend the harmonizing tools by confinement of one more salt to the matrix pores. Novel CSPMs based on a binary mixture of lithium, calcium, and barium halides inside various mesoporous matrices were synthesized with wide variation of the relative salts content. Their phase composition and sorption equilibrium with water, methanol and ammonia vapour were studied by XRD and TG techniques. It was shown that the formation of a homogeneous solid solution of the salts led to changing the equilibrium temperature (pressure) of the solvation. Thus, the confinement of binary salt systems to the matrix pores can be an effective tool for designing innovative materials with predetermined sorption properties adapted to particular AHT cycles.     

H NMR study of thermotropic phase transitions in D2O solutions of poly(N-isopropylmethacrylamide)/poly(vinyl methyl ether) mixtures

¹H NMR spectroscopy was used to investigate thermotropic phase transitions in D₂O solutions of poly(N-isopropylmethacrylamide) (PIPMAm)/poly(vinyl methyl ether) (PVME) mixtures. In all studied solutions (polymer concentrations c=0.1-10 wt%) two phase transitions were detected at temperatures roughly corresponding to different lower critical solution temperatures of PIPMAm and PVME. While the phase transition of PVME component (located at lower temperatures) is not affected by the presence of PIPMAm in the mixture, the phase transition temperatures of PIPMAm component (located at higher temperatures) are affected by the phase separation of the PVME component. Measurements of ¹H spin-spin relaxation of residual water (HDO) molecules revealed that above the phase transition, a certain portion of water molecules is bound to polymer globular structures. A major part of bound water is present in globular structures of predominating polymer component in the mixture.     

The Robot Scientist Adam

Despite science's great intellectual prestige, developing robot scientists will probably be simpler than developing general AI systems because there is no essential need to take into account the social milieu.     

Ge quantum dot arrays grown by ultrahigh vacuum molecular-beam epitaxy on the Si(001) surface: nucleation,morphology, and CMOS compatibility

Issues of morphology, nucleation, and growth of Ge cluster arrays deposited by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface are considered. Difference in nucleation of quantum dots during Ge deposition at low (≲600°C) and high (≳600°C) temperatures is studied by high resolution scanning tunneling microscopy. The atomic models of growth of both species of Ge huts--pyramids and wedges-- are proposed. The growth cycle of Ge QD arrays at low temperatures is explored. A problem of lowering of the array formation temperature is discussed with the focus on CMOS compatibility of the entire process; a special attention is paid upon approaches to reduction of treatment temperature during the Si(001) surface pre-growth cleaning, which is at once a key and the highest-temperature phase of the Ge/Si(001) quantum dot dense array formation process. The temperature of the Si clean surface preparation, the final high-temperature step of which is, as a rule, carried out directly in the MBE chamber just before the structure deposition, determines the compatibility of formation process of Ge-QD-array based devices with the CMOS manufacturing cycle. Silicon surface hydrogenation at the final stage of its wet chemical etching during the preliminary cleaning is proposed as a possible way of efficient reduction of the Si wafer pre-growth annealing temperature.     

Food composition databases for effective quality nutritional care

Background and objectives

The main aim of this study was to validate a nutrient-estimation method applied using OPEN, a Slovenian platform for clinical nutrition. As the most desirable validation is a direct comparison of the calculated values with the values obtained from a chemical analysis of the same food, we performed a chemical analysis and a calculation for a representative set of daily meals (n = 20) and compared the data. The secondary aim was to evaluate the usability of the OPEN for dietary assessment.

Methods

We used a Student’s t test to observe any differences between the analysed and calculated nutrient-content data, considering the 0.01 significance level.

Results

No statistically significant differences were observed in the mean contents of energy, total dietary fibre, water, macro-nutrients, and selected essential minerals: Ca, Fe, Mg, Zn, Na, P, Cu and I. We notice statistically significant difference in the mean calculated and analytical values of selenium.

Conclusions

We noticed remarkable, but not statistically significant, difference in the mean values of iodine (−11%). The present study also indicates that the OPEN is a useful and cost-effective tool for both dieticians and patients.     

Multiplexed dot immunoassay using Ag nanocubes,Au/Ag alloy nanoparticles,and Au/Ag nanocages

We report the first application of Ag nanocubes, Au/Ag alloy nanoparticles, and Au/Ag nanocages in a multiplexed dot immunoassay. The assay principle is based on the staining of analyte drops on a nitrocellulose membrane strip by using multicolor nanoparticles conjugated with biospecific probing molecules. Nanoparticles were prepared by a galvanic replacement reaction between the Ag atoms of silver nanocubes and Au ions of tetrachloroauric acid. Depending on the Ag/Au conversion ratio, the particle plasmon resonance was tuned from 450 to 700 nm and the suspension color changed from yellow to blue. The particles of yellow, red, and blue suspensions were functionalized with chicken, rat, and mouse immuno gamma globulin (IgG) molecular probes, respectively. The multiplex capability of the assay was illustrated by a proof-of-concept experiment involving simultaneous one-step determination of target molecules (rabbit anti-chicken, anti-rat, and anti-mouse antibodies) with a mixture of fabricated conjugates. Under naked eye examination, no cross-colored spots or nonspecific bioconjugate adsorption were observed, and the low detection limit was about 20 fmol.