Вивчення процесу синтезу нанокристалічних плівок двооксиду титану в розряді магнетронного типу за його оптичними та плазмодинамічними характеристиками

Наведено результати експериментального дослiдження плазмодинамiчних i оптичних характеристик цилiндричного газового розряду магнетронного типу в умовах безперервного контролю спектра, випромiнюваного плазмою в дiапазонi 350–820 нм. Визначено умови для синтезу бiнарної сполуки TiО₂, якi забезпечуються пiдтримкою величини iнтенсивностi спектральних лiнiй реагуючих компонентiв i плазмоутворюючого газу. Розглянуто можливiсть контролю умов одержання плiвок TiО₂ як по спектральних характеристиках плазми розряду, так i по змiнi розрядної напруги. Елiпсометричнi дослiдження нанокристалiчних плiвок двооксиду титану показали наявнiсть залежностi показника переломлення вiд товщини плiвки.We present the results of experimental researches of plasmodynamic and optical characteristics of a magnetron-type cylindrical gas discharge. The study was carried out provided a permanent monitoring of the spectrum emitted by plasma in the range 350–820 nm. For the synthesis of binary compound TiO₂, we have determined conditions which can be ensured by a support of the intensity of spectral lines emitted by reacting components and plasma-forming gas. A possibility to control the conditions of the fabrication of a TiO₂ film with the use of both the spectral characteristics of a discharge plasma and a variation of the discharge voltage has been analyzed. Ellipsometric and spectral studies of nanocrystalline titanium dioxide films revealed the dependence of the refractive index of a film on the film thickness.Приведены результаты экспериментального исследования плазмодинамических и оптических характеристик цилиндрического газового разряда магнетронного типа в условиях непрерывного контроля спектра, излучаемого плазмой в диапазоне 350–820 нм. Определены условия для синтеза бинарного соединения TiО₂, которые обеспечиваются поддержанием величины интенсивности спектральных линий реагирующих компонент и плазмообразующего газа. Рассмотрена возможность контроля условий получения пленок TiO₂ как по спектральным характеристикам плазмы разряда, так и по изменению разрядного напряжения. Эллипсометрические и спектральные исследования нанокристаллических пленок диоксида титана показали наличие зависимости показателя преломления от толщины пленки

Intercapsomeric disulfide bonds in papillomavirus assembly and disassembly.

In order to analyze bonding contacts that stabilize the virion or promote capsid assembly, bovine papillomavirus (BPV) virions were subjected to buffer conditions known to disrupt polyomavirus virions. At physiologic ionic strength, incubation with dithiothreitol (DTT), EGTA, or DTT plus EGTA did not disrupt BPV virions as determined by electron microscopy. However, incubation of virions with DTT rendered the BPV L1 protein susceptible to trypsin cleavage at its carboxy terminus and rendered the genome susceptible to digestion with DNase I. When DTT-treated BPV virions were analyzed by analytical ultracentrifugation, they sedimented at 230S compared with 273S for untreated virions, suggesting a capsid shell expansion. Incubation with EGTA had no effect on trypsin or DNase I sensitivity and only a small effect upon the virion S value. A single cysteine residue conserved among BPV and human papillomavirus (HPV) L1 proteins resides within the trypsin-sensitive carboxy terminus of L1, which is required for capsid assembly. A recombinant HPV type 11 L1 protein, which was purified after expression in Escherichia coli and which has a Cys-to-Gly change at this position (Cys424), formed pentamers; however, unlike the wild-type protein, these mutant pentamers could no longer assemble in vitro into capsid-like structures. These results indicate an important role for interpentamer disulfide bonds in papillomavirus capsid assembly and disassembly and suggest a mechanism of virus uncoating in the reducing environment of the cytoplasm

Grain size, composition, porosity and permeability contrasts within cross-bedded sandstones in Tertiary fluvial deposits, central Spain

Permeability measured with a portable probe pcrmcflmeter on outcrops of cross·bcdded sandstones ranges betwecn 0·9 and 19 O. The highest pcrmeability (2-19 0 with an avcrage of8·5 D) occurs in thc coarsest grained foresct laminae (CFL). intermediate values (2-120 with an average of 5·3 D) occur in fincr grained foreset laminac (FFL) and thc lowest values (0·9-1 0 0 with un avcrage of 4·8 D) occur in boltomsct laycrs (BL). In the cross·bcds the uverage grain sizc rangcs from medium graincd sand in the CFL to finc grained s,lnd in thc FFL and BL. In all three subf'lcies. the average size of the primary pores is approximately It/> unit smaller than the averagc grain size. The abundance of unstablc carbonatc clasts correlatcs with incrcasing avcrage grain size, micritic clasts being most abundant in the CFL. Converscly. quartz content incrcascs with decreasing grain size and is highest in the FFL and BL. Oiagenetic destruction of primary porosity by compact ion and cementation. as well �IS generation of sccondary porosity through dissolution, were controlled by the original mineralogical composition of the sand. Contrasts in grain size detcrmine the primary pore size contrasts and differences in composition bctwecn CFL. FFL and BL. Permeability contrasts reflect variations in averagc primary pore size rather than differenccs in total porosity. Probe permeability contrasts between eFL. FFL and BL depend on contrasts in llverage pore size and contrasts in mineralogical composition between the subfacies