Structure and swelling-release behaviour of poly(vinyl pyrrolidone) (PVP) and acrylic acid (AAc) copolymer hydrogels prepared by gamma irradiation

Copolymer network hydrogels were prepared by gamma irradiation of aqueous solutions of poly(vinyl pyrrolidone) (PVP) and acrylic acid monomer (AAc). The composition of the final hydrogels compared to the composition of the initial preparation solutions of hydrogels was determined. The chemical structure and nature of bonding was characterized by IR spectroscopy analysis, while the thermal durability of the prepared hydrogels was assessed by thermogravimetric analysis (TGA). The kinetic swelling in water and the pH-sensitivity of PVP/AAc copolymer hydrogels was studied. The drug release properties of PVP/AAc hydrogels taking methyl orange indicator as a drug model was investigated. The IR spectra indicate the formation of copolymer networks, whereas the TGA study showed that the PVP/AAc hydrogels possess higher thermal stability than pure PAAc and lower than PVP hydrogels. The kinetic swelling in water showed that all the hydrogels reached equilibrium after 24 h and that the degree of swelling increases with increasing the ratio of AAc in the initial feeding solutions. It was found that the degree of swelling of PVP/AAc hydrogels increases greatly within the pH range 4-7 depending on composition.     

Resolution limits in magic-angle rotation NMR spectra of polycrystalline solids

Dependence of linewidth in porton-decoupled ¹³C NMR spectra of diamagnetic polycrystalline samples on external magnetic field strength is studied. Spectral resolution is limited by magnetic heterogencity of powder samples. It is suggested that in magic-angle rotation spectra, the linewidth is determined by the amsotropy of the magnetic susceptibility Δ_xυ rather than _xυ of the crystallites.     

A novel methodology for the synthesis of complexes containing long carbon chains linking metal centres: molecular structures of [Ru(dppe)Cp*]2(mu-C14) and [Co3(mu-dppm)(CO)7]2(mu3:mu3-C16)

Elimination of AuX(PR3)(X = halogen, R = Ph, tol) occurs readily in reactions between compounds containing C(sp)- or C(sp2)-X bonds and alkynyl or polyynyl gold(I) complexes; this reaction has been applied to the syntheses of complexes containing a variety of metal centres linked by C(n) chains (n up to 16).     

2-Alkyl-3-chloro(bromo)tetrahydrofurans

The reaction ofRS(SR)-2,3-dibromo- and 2,3-dichlorotetrahydrofurans with ethylmagnesium bromide in ether was investigated. It was shown that the main reaction products are 2-ethyl-3-bromotetrahydrofuran (27%) and 3-bromo-2-(2-ethyl-3-tetrahydrofuryl)tetrahydrofuran (65%) in the first case and 2-ethyl-3-chlorotetrahydrofuran (33%) and 3-chloro-2-(3-chloro-2-tetrahydrofuryl)tetrahydrofuran (65%) in the second.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. I. M. Gubkin Moscow Institute of Petroleum and Gas, 111917 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1430–1434, June, 1992.     

Effect of acidity of the medium and polarization of the surface on albumin adsorption by carbon fibers

Adsorption of bovine serum albumin (BSA) was studied at different acidities of the medium on the non-charged and titanium hydroxide-modified surfaces of the carbon fibers (ACF and ACF-B (Ti)). The fiber covered with titanium hydroxide was shown to have the highest adsorption capacity at pH = 4.7, which is close to the isoelectric point of BSA. The cathodic polarization has the greatest effect on the BSA desorption ability, which enabled the determination of conditions for recovering the adsorption capacity of the fibrous sorbent.     

Vibrational spectra and conformational isomerism of calixarene building blocks: 2-benzylphenol

The conformations and vibrational spectra of 2-benzylphenol have been analysed within the framework of scaled quantum mechanics. It is shown that the solid-state conformation of the 2-benzylphenol molecule corresponds to one of four potential energy minima predicted by non-empirical quantum chemical calculations for the isolated molecule. In the molten state and in diluted CCl4 solutions of the title compound this conformer coexists with another two spectroscopically detected conformations. The presence of several conformers gives rise to the observation of the corresponding number of vsCH2 and vasCH2 bands in the IR spectra, thus providing experimental evidence of the conformational sensitivity of the vCH2 frequencies. It is shown that vCH2 wavenumbers of different kinds of molecules, containing diphenylmethane fragments, are determined by the dihedral angles between the planes of the aromatic rings and the plane of the connecting methylene bridges, except for the case of short intramolecular contacts with the participation of the methylene protons.     

Chemical synthesis of the innate immune modulator – bacterial d-glycero-β-d-manno-heptose-1,7-bisphosphate (HBP)

The bacterial metabolite and potent innate immune modulator d-glycero-β-d-manno-heptose-1,7-bisphosphate (HBP) and its α-configured counterpart d-glycero-α-d-manno-heptose-1,7-bisphosphate were synthesized via stereoselective anomeric phosphorylation of the peracetylated d,d-heptose 7-dibenzylphosphate by exploiting different nucleophilicity of equatorial and axial lactols in the d-manno-series. We also report a novel approach for anomeric phosphorylation using modified Mitsunobu reaction conditions and provide the first full structural characterization of HBP. The first chemical synthesis of HBP offers access to an anomerically pure structurally defined probe for biological studies and to a lead compound operating as a powerful stimulator of intracellular signaling for possible therapeutic immunomodulation.     

A Framework for Comparative Evaluation of Dosimetric Methods to Triage a Large Population Following a Radiological Event

BACKGROUND: To prepare for a possible major radiation disaster involving large numbers of potentially exposed people, it is important to be able to rapidly and accurately triage people for treatment or not, factoring in the likely conditions and available resources. To date, planners have had to create guidelines for triage based on methods for estimating dose that are clinically available and which use evidence extrapolated from unrelated conditions. Current guidelines consequently focus on measuring clinical symptoms (e.g., time-to-vomiting), which may not be subject to the same verification of standard methods and validation processes required for governmental approval processes of new and modified procedures. Biodosimeters under development have not yet been formally approved for this use. Neither set of methods has been tested in settings involving large-scale populations at risk for exposure. OBJECTIVE: To propose a framework for comparative evaluation of methods for such triage and to evaluate biodosimetric methods that are currently recommended and new methods as they are developed. METHODS: We adapt the NIH model of scientific evaluations and sciences needed for effective translational research to apply to biodosimetry for triaging very large populations following a radiation event. We detail criteria for translating basic science about dosimetry into effective multi-stage triage of large populations and illustrate it by analyzing 3 current guidelines and 3 advanced methods for biodosimetry. CONCLUSIONS: This framework for evaluating dosimetry in large populations is a useful technique to compare the strengths and weaknesses of different dosimetry methods. It can help policy-makers and planners not only to compare the methods' strengths and weaknesses for their intended use but also to develop an integrated approach to maximize their effectiveness. It also reveals weaknesses in methods that would benefit from further research and evaluation.     

Quantum Dot-Antibody Conjugates for Immunofluorescence Studies of Biomolecules and Subcellular Structures

Journal of Fluorescence - Quantum dots, or nanoscale semiconductors, are one of the most important materials for various research and development purposes. Due to their advantageous...     

The system of self-consistent QSPR-models for refractive index of polymers

Structural Chemistry - Quantitative structure–property/activity relationships (QSPRs/QSARs) are a component of modern natural science. The system of self-consistent models is a specific...