Young's modulus of polyelectrolyte multilayers from microcapsule swelling

We measure Young's modulus of a free polyelectrolyte multilayer film by studying osmotically induced swelling of polyelectrolyte multilayer microcapsules filled with the polyelectrolyte solution. Different filling techniques and core templates were used for the capsule preparation. Varying the concentration of the polyelectrolyte inside the capsule, its radius and the shell thickness yielded an estimate of an upper limit for Young's modulus of the order of 100 MPa. This corresponds to an elastomer and reflects strong interactions between polyanions and polycations in the multilayer

Structure of reaction products of some α, β-unsaturated carbonyl compounds with trimethyl phosphite and tri(dimethylamino)phosphine

1. Trimethyl phosphite adds to 1,3-diphenyl-5-benzalbarbituric acid at -14°C to give a 1:1 adduct with a bipolar structure, which isomerizes to the methyl ether of the enolic form of the dimethyl ester of α-(1,3-diphenyl-5-barbituryl)benzylphosphonic acid. The latter is also formed when the reaction is run at room temperature. 2. The hydrolysis of the methyl ether of the enolic form of α-(1,3-diphenyl-5-barbituryl)benzylphosphonic acid leads to the formation of the enolic form of the dimethyl ester of α-(1,3-diphenyl-5-barbituryl)·benzylphosphonic acid. 3. The reaction of tri(dimethylamino)phosphine with 1,3-diphenyl-5-benzalbarbituric acid gave the crystalline 1:1 adduct, which had the structure of a bipolar ion containing the P-C bond. 4. The values of the dipole moments, as well as the parameters of the UV spectra, are given for a number of bipolar ions that were obtained using tri(dimethylamino)phosphine. © 1972 Consultants Bureau

Optical echo in photonic crystals

The dynamics of photonic wavepacket in the effective oscillator potential is studied. The oscillator potential is constructed on a base of one dimensional photonic crystal with a period of unit cell adiabatically varied in space. The structure has a locally equidistant discrete spectrum. This leads to an echo effect, i.e. the periodical reconstruction of the packet shape. The effect can be observed in a nonlinear response of the system. Numerical estimations for porous-silicon based structures are presented for femtosecond Ti:Sapphire laser pump.Comment: 4 page

Structure and properties of reaction products of benzylidenebenzoylacetone with trimethyl phosphite and dimethylphosphorous acid

1. Trimethyl phosphite reacts with benzylidenebenzoylacetone to give the 1:1 adduct, which contains a pentacoordinated phosphorus atom. 2. In solution the obtained 1,2-oxaphospholene represents a mixture of two isomers, while in the solid state it has the structure of 2,2,2-trimethoxy-3,5-diphenyl-4-acetyl-1,2-oxa-4-phospholene. 3. The spectral and some of the chemical properties of the obtained phosphorane were studied. 4. Dimethylphosphorous acid adds to benzylidenebenzoylacetone to give the dimethyl ester of 1-phenyl-2-acetyl-2-benzoylethylphosphonic acid. Its keto-enol tautomerism was studied employing UV spectroscopy. © 1975 Plenum Publishing Corporation

Nonlinear acoustic waves in channels with variable cross sections

The point symmetry group is studied for the generalized Webster-type equation describing non-linear acoustic waves in lossy channels with variable cross sections. It is shown that, for certain types of cross section profiles, the admitted symmetry group is extended and the invariant solutions corresponding to these profiles are obtained. Approximate analytic solutions to the generalized Webster equation are derived for channels with smoothly varying cross sections and arbitrary initial conditions.Comment: Revtex4, 10 pages, 2 figure. This is an enlarged contribution to Acoustical Physics, 2012, v.58, No.3, p.269-276 with modest stylistic corrections introduced mainly in the Introduction and References. Several typos were also correcte

Quaternionic factorization of the Schroedinger operator and its applications to some first order systems of mathematical physics

We consider the following first order systems of mathematical physics. 1.The Dirac equation with scalar potential. 2.The Dirac equation with electric potential. 3.The Dirac equation with pseudoscalar potential. 4.The system describing non-linear force free magnetic fields or Beltrami fields with nonconstant proportionality factor. 5.The Maxwell equations for slowly changing media. 6.The static Maxwell system. We show that all this variety of first order systems reduces to a single quaternionic equation the analysis of which in its turn reduces to the solution of a Schroedinger equation with biquaternionic potential. In some important situations the biquaternionic potential can be diagonalized and converted into scalar potentials

On discretization in time in simulations of particulate flows

We propose a time discretization scheme for a class of ordinary differential equations arising in simulations of fluid/particle flows. The scheme is intended to work robustly in the lubrication regime when the distance between two particles immersed in the fluid or between a particle and the wall tends to zero. The idea consists in introducing a small threshold for the particle-wall distance below which the real trajectory of the particle is replaced by an approximated one where the distance is kept equal to the threshold value. The error of this approximation is estimated both theoretically and by numerical experiments. Our time marching scheme can be easily incorporated into a full simulation method where the velocity of the fluid is obtained by a numerical solution to Stokes or Navier-Stokes equations. We also provide a derivation of the asymptotic expansion for the lubrication force (used in our numerical experiments) acting on a disk immersed in a Newtonian fluid and approaching the wall. The method of this derivation is new and can be easily adapted to other cases

Crosstalk between Mitochondrial and Sarcoplasmic Reticulum Ca2+ Cycling Modulates Cardiac Pacemaker Cell Automaticity

Mitochondria dynamically buffer cytosolic Ca(2+) in cardiac ventricular cells and this affects the Ca(2+) load of the sarcoplasmic reticulum (SR). In sinoatrial-node cells (SANC) the SR generates periodic local, subsarcolemmal Ca(2+) releases (LCRs) that depend upon the SR load and are involved in SANC automaticity: LCRs activate an inward Na(+)-Ca(2+) exchange current to accelerate the diastolic depolarization, prompting the ensemble of surface membrane ion channels to generate the next action potential (AP).To determine if mitochondrial Ca(2+) (Ca(2+) (m)), cytosolic Ca(2+) (Ca(2+) (c))-SR-Ca(2+) crosstalk occurs in single rabbit SANC, and how this may relate to SANC normal automaticity.Inhibition of mitochondrial Ca(2+) influx into (Ru360) or Ca(2+) efflux from (CGP-37157) decreased [Ca(2+)](m) to 80 ± 8% control or increased [Ca(2+)](m) to 119 ± 7% control, respectively. Concurrent with inhibition of mitochondrial Ca(2+) influx or efflux, the SR Ca(2+) load, and LCR size, duration, amplitude and period (imaged via confocal linescan) significantly increased or decreased, respectively. Changes in total ensemble LCR Ca(2+) signal were highly correlated with the change in the SR Ca(2+) load (r(2) = 0.97). Changes in the spontaneous AP cycle length (Ru360, 111 ± 1% control; CGP-37157, 89 ± 2% control) in response to changes in [Ca(2+)](m) were predicted by concurrent changes in LCR period (r(2) = 0.84).A change in SANC Ca(2+) (m) flux translates into a change in the AP firing rate by effecting changes in Ca(2+) (c) and SR Ca(2+) loading, which affects the characteristics of spontaneous SR Ca(2+) release

Evaluating methane inventories by isotopic analysis in the London region

A thorough understanding of methane sources is necessary to accomplish methane reduction targets. Urban environments, where a large variety of methane sources coexist, are one of the most complex areas to investigate. Methane sources are characterised by specific δ13C-CH4 signatures, so high precision stable isotope analysis of atmospheric methane can be used to give a better understanding of urban sources and their partition in a source mix. Diurnal measurements of methane and carbon dioxide mole fraction, and isotopic values at King’s College London, enabled assessment of the isotopic signal of the source mix in central London. Surveys with a mobile measurement system in the London region were also carried out for detection of methane plumes at near ground level, in order to evaluate the spatial allocation of sources suggested by the inventories. The measured isotopic signal in central London (−45.7 ±0.5‰) was more than 2‰ higher than the isotopic value calculated using emission inventories and updated δ13C-CH4 signatures. Besides, during the mobile surveys, many gas leaks were identified that are not included in the inventories. This suggests that a revision of the source distribution given by the emission inventories is needed

Значение информированности пациентов с ревматическими заболеваниямио наличии у них коморбидных инфекционных заболеваний

Subjects and methods. Four hundred and ninety-five patients with various RDs were interviewed by a questionnaire. A comparison group comprised 250 patients with non-RDs and 150 physicians. Results. The patients with RD frequently reported to have nasopharyngeal infection. The latter was accompanied by an exacerbation of articular syndrome in more than half of the patients with RD. The rate of pneumonias experienced by patients with systemic lupus erythematosus (SLE) (10/55) engages our attention. Urogenital tract infections (mainly cystitis and pyelonephritis) are more typical of patients with rheumatic arthritis (RA) and those with osteoarthrosis (OA), respectively. The clinical manifestations of herpes simplex virus type 1 (HSV-1) recurred most frequently in patients with SLE and those with OA and less in patients with RA. The percentage of HSV-1 recurrences was high in the medical staff. Conclusion. The findings suggest that it is necessary to thoroughly collect medical history data especially in patients who need aggressive immunosuppressive therapy as activation of latent infection makes management of these patients difficultЦель исследования - уточнить информированность больных ревматическими заболеваниями (РЗ) о наличии у них коморбидных заболеваний, обусловленных инфекцией. Материал и методы. Проведено анкетирование 495 пациентов с различными РЗ. В группу сравнения включено 250 пациентов с неревматическими заболеваниями и 150 врачей. Результаты исследования. Пациенты с РЗ часто отмечали наличие носоглоточной инфекции. Более чем у половины пациентов с РЗ эта инфекция сопровождалась обострением суставного синдрома. Обращает на себя внимание частота перенесенной пневмонии у больных системной красной волчанкой - СКВ (у 10 из 55). Инфекция мочеполовой системы более характерна для пациентов с ревматоидным артритом - РА (преимущественно цистит) и остеоартрозом - ОА (пиелонефрит). Клинические проявления вируса простого герпеса 1-го типа (ВПГ 1) наиболее часто рецидивировали у больных СКВ и ОА, реже РА. Высок процент рецидивов ВПГ 1 у медицинского персонала. Заключение. Полученные результаты свидетельствуют о необходимости тщательного сбора анамнеза, особенно у пациентов, нуждающихся в агрессивной иммуносупрессивной терапии, так как активация латентной инфекции осложняет ведение этих больных