Synthesis and properties of amphiphilic maleic acid copolymers

New amphiphilic polymers derived from maleic acid copolymers and containing stearyl or oleyl residues were prepared. Their physicochemical properties were studied, and the possibility of using them as carriers for antifungal agents was examined with Amphotericin B as example.     

Hydration of Strontium Chloride and Rare-Earth Element Oxychlorides

Hydration and dehydration (on calcination) of SrCl₂, YOCl, and HoOCl powders were studied.     

On the Viscous Drag of a Plate with Spherical Recesses

The drag of flat plates with spherical recesses was measured using the direct balance method. The experiments were run in a low-turbulence wind tunnel with a cross-section measuring 1000 × 1000 mm and a length of 400 mm. Three surfaces with recesses 7.0, 3.9, and 1.3 mm in diameter and 0.5, 0.3, and 0.2 mm deep, respectively, were tested. It is shown that on the Reynolds and Mach number ranges Re= (3–9)· 10⁶ and M 0.3 the spherical recesses add to the drag of a flat plate in turbulent flow. The recesses have almost no effect on the location of laminar-turbulent transition, which occurs at Re_t 3· 10⁶.     

Synthesis of 3-(p-methoxyphenyl)-1, 3-dimethylspiro (indoline-2,2′- [2H-1]-benzopyrans) and investigation of the electronic absorption spectra of their merocyanine forms

Photochromic indoline spiropyrans containing a p-methoxyphenyl substituent in the 3-position were synthesized, and the electronic absorption spectra of their merocyanine forms were measured.     

Preparation of aliphatic diketones by hydrogenolysis of difurylalkanes and difurylalkenes

Conclusions The hydrogenolysis of di-(2-furyl)alkanes or di-(2-furyl)alkenes in the vapor phase over Pt/C is a new and general method for the preparation of aliphatic diketones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2382–2384, October, 1973.     

Evolution of dislocation structure during deformation of γ-irradiated LiF crystals

The effect of γ irradiation on the mechanical characteristics and dislocation structure of slip bands in LiF crystals is studied at doses D⩽7.3×10⁸ R. Irradiation causes a substantial increase (up to a factor of 30) in the yield stress τ _y of the crystals, with τ _y ∝ D ^0.4 in the first approximation. The deformation shear increases in the slip bands of irradiated crystals, as do the densities of the screw and edge dislocation components, while the dislocation mean free paths decrease. Irradiation also raises the probability of twinning cross slip for screw dislocations. The observed effects are assumed to be related to the formation of a different kind of defects in the irradiated crystals, primarily clusters of implanted atoms. Fiz. Tverd. Tela (St. Petersburg) 39, 1072–1075 (June 1997)     

The conversion of 4, 7-diketocaprylic acid and its ester into cyclic compounds

Conclusions 4,7-Diketocaprylic acid and its ethyl ester are converted into carbonyl or carboxyl derivatives of cyclopentenone, pyrrole, or -lactone by the action of various dehydrating agents.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1630–1631, July, 1968.     

Microwave noise of a thin-film YBa2Cu3O7−x bridge in the resistive state

The effective input noise temperature T _e of a bridge made from a highly oriented YBaCuO film is measured at a frequency of 4.6 GHz. The bridge is brought to a weakly resistive state by a dc current, by microwave radiation at a frequency of 9.4 GHz, or by a combination of the two. Along with the noise temperature, the current-voltage characteristics and impedance of the bridge are also measured at a frequency of 4.6 GHz. At T=78 K the value of T _e does not exceed 120 K. Analysis of the results allows one to compare the experimental values of T _e with the values determined by the equilibrium Nyquist noise of overheated normal domains and indicates the presence of excess noise at a level comparable to the Nyquist noise. Zh. Tekh. Fiz. 67, 89–93 (February 1997)     

ENDOR/HYSCORE studies of the common intermediate trapped during nitrogenase reduction of N2H2, CH3N2H, and N2H4 support an alternating reaction pathway for N2 reduction

Enzymatic N(2) reduction proceeds along a reaction pathway composed of a sequence of intermediate states generated as a dinitrogen bound to the active-site iron-molybdenum cofactor (FeMo-co) of the nitrogenase MoFe protein undergoes six steps of hydrogenation (e(-)/H(+) delivery). There are two competing proposals for the reaction pathway, and they invoke different intermediates. In the 'Distal' (D) pathway, a single N of N(2) is hydrogenated in three steps until the first NH(3) is liberated, and then the remaining nitrido-N is hydrogenated three more times to yield the second NH(3). In the 'Alternating' (A) pathway, the two N's instead are hydrogenated alternately, with a hydrazine-bound intermediate formed after four steps of hydrogenation and the first NH(3) liberated only during the fifth step. A recent combination of X/Q-band EPR and (15)N, (1,2)H ENDOR measurements suggested that states trapped during turnover of the α-70(Ala)/α-195(Gln) MoFe protein with diazene or hydrazine as substrate correspond to a common intermediate (here denoted I) in which FeMo-co binds a substrate-derived [N(x)H(y)] moiety, and measurements reported here show that turnover with methyldiazene generates the same intermediate. In the present report we describe X/Q-band EPR and (14/15)N, (1,2)H ENDOR/HYSCORE/ESEEM measurements that characterize the N-atom(s) and proton(s) associated with this moiety. The experiments establish that turnover with N(2)H(2), CH(3)N(2)H, and N(2)H(4) in fact generates a common intermediate, I, and show that the N-N bond of substrate has been cleaved in I. Analysis of this finding leads us to conclude that nitrogenase reduces N(2)H(2), CH(3)N(2)H, and N(2)H(4) via a common A reaction pathway, and that the same is true for N(2) itself, with Fe ion(s) providing the site of reaction.