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The spectrum ω ( G ) of a finite group G is the set of orders of elements of G. We present a polynomial-time algorithm that, given a finite set M of positive integers, outputs either an empty set or a finite simple group G. In the former case, there is no finite simple group H with M = ω ( H ) , while in the latter case, M ⊆ ω ( G ) and M ≠ ω ( H ) for all finite simple groups H with ω ( H ) ≠ ω ( G ) .

Gas-phase collisions of Gly and Ala with free electrons were employed to form positive ions at well determined energies. At elevated molecular vapor pressure, protonated [Gly+H]+ and [Ala+H]+ ions were also observed. The appearance energies of [Gly+H]+ and [Ala+H]+ were both determined as 0.30 ± 0.14 eV higher than the ionization energies of their M + congeners. Quantum chemical calculations predict proton transfer reactions rather than hydrogen atom abstraction reactions as the likely [M+H]+ forming method in our experiment. Microcanonical rate coefficient calculations using B3LYP/6-311++G(2d,p) frequencies and rotational constants, support abstraction of a Calpha proton for glycine, whereas the C-terminal proton abstraction mechanism was found as being more favorable for alanine. Additionally, substantial immonium ion formation was observed at experimental energies identical to either the protonated product or cation radical for glycine and alanine, respectively. Theoretical barriers to M + cation radical fragmentation to HRCNH2+ indicate that they are product-limited and that the glycine barriers are generally larger than those for alanine.

Metal–insulator–semiconductor structures based on n -Hg 1− x Cd x Te ( x = 0.19–0.25) were grown by molecular-beam epitaxy on the GaAs (0 1 3) substrates. Near-surface graded-gap layers with high CdTe content were formed on both sides of the epitaxial HgCdTe. Admittance of these structures was studied experimentally in a wide temperature range (8–150) K. It is shown that an increase in the composition of the working layer and a decrease in temperature lead to a decrease in the frequency of transition to high-frequency behavior of the capacitance–voltage characteristics. The differential resistance of space charge region in the strong inversion increases with the composition of the working layer and for x = 0.22 and 0.25, the differential resistance is limited by the Shockley-Read generation. The values of the differential resistance of space charge region at different frequencies and temperatures were found.

The characteristics of SWIR (1.6–3 μm) 320 × 256 and 1024 × 1024 focal plane arrays (FPA’s) based on n-type In-doped HgCdTe heteroepitaxial layers are reported. The HgCdTe layers were grown by molecular beam epitaxy on silicon substrates with ZnTe and CdTe buffer layers. p–n junctions were formed by arsenic ion implantation into HgCdTe film. Reverse current in the temperature range from 210 to 330 K was found to be limited by the diffusion mechanism. At the same time in the temperature range from 140 to 210 K the reverse current was dominated by the thermal generation of charge carriers through deep traps located in the middle of the band gap. At 170 K NETD was less than 40 mK.

A specialized architecture based on peer servers is suggested for the development of distributed control systems with advanced reliability and operating speed; implementation is used in the Novosibirsk subway automated traffic control system.

Resonant electron capture by C 2 Cl 4 , C 2 HCl 3 , cis -, trans - and geminal-C 2 H 2 Cl 2 , C 2 HBr 3 , cis - and trans -C 2 H 2 Br 2 and C 2 H 3 Br has been studied. A new method for the measurements of absolute electron attachment cross-sections based on the interface of a gas-chromatography and a reflectron-time-of-flight-mass spectrometer has been developed and the method was applied for these compounds.

The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) cascade plays an important role in gene expression regulation during memory formation in both vertebrates and invertebrates. MAPK/ERK regulates gene expression through phosphorylation of transcription factors binding to the regulatory elements SRE and CRE of target genes. Previously we reported that juvenile snails Helix lucorum differ from adult animals in a spectrum of transcription factors binding to DNA regulatory elements SRE and AP-1. In this study we analyzed the expression and activation of MAPK/ERK in CNS of H. lucorum during formation of the conditioned avoidance reflex at different stages of postnatal ontogenesis. Under conditions of learning, juvenile snails (aged 2-3 months) possessing immature mechanisms of avoidance reflex plasticity showed dramatically low level of phosphorylation and, correspondingly, low activation of MAPK/ERK in comparison to adult animals. Beside this, the MAPK/ERK cascade was not activated after 10 and 60 min after learning in juvenile snails in contrast to adults, while basal expression level of this kinase was similar in juveniles and adults. Low activation of MAPK/ERK cascade can cause a deficiency in phosphorylation of downstream transcription factors binding to SRE and thereby influence the expression of early response genes (particularly, of the family AP-1) and late response genes necessary for cellular and synaptic plasticity. These observations suggest that the MAPK/ERK regulatory cascade plays an essential role in the formation of conditioned avoidance reflexes in Helix. Low activation of this cascade might be one of the reasons for deficiency of long-term memory formation during avoidance learning in juvenile animals.

Cycloaddition reactions of fluorinated 1,3,4-oxadiazoles with conjugated and unconjugated dienes was studied. The reactions resulted in the formation of products of double cycloaddition (7-oxabicycloheptane type compounds), along with products of intramolecular cycloaddition (oxatricyclic and oxatetracyclic compounds). The structure of 4-(trifluoromethyl)-2-ethoxycarbonyl-1,6-dimethyl-3-oxatricyclo[2.2.1.0 2,6 ]heptane was confirmed by single crystal X-ray diffraction analysis.

Modification of a method for processing positive ion ionization efficiency curves of polyatomic molecules, as developed earlier by Mark and coworkers, has been described. Based on the method, the first, second, and third ionization energies of C 60 have been re-examined and found to be in excellent agreement with the most reliable literature data. The ionization energies for C 60 H 18 and C 60 H 36 have been measured for the first time and were established as 7.3±0.3 eV and 7.01±0.25 eV, respectively. Although the appearance energy of C 60 H 36 2+ (18.7±0.2 eV) has been determined to be lower than that of C 60 2+ (18.98±0.35 eV), the reverse scenario is true for the second ionization energies of C 60 H 36 and C 60 .

Fullerenodendrimers have been studied by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (ToF) mass spectrometry. The compounds under investigation included the first-, second- and slightly modified second-generation phenylacetylene dendritic C 60 monoligands. The bimodal structure of these fullerenodendrimers is reflected in the charge localisation and ion formation during MALDI mass spectrometry. While metal ion (Ag + ) attachment occurs through interaction with the dentritic ligand, electron-transfer ionization seems to involve predominately the fullerene moiety. The latter conclusion is particularly evident for the formation of the negatively charged molecular ions. In direct laser ablation experiments, the coalescence reactivity has been compared with methano[60]fullerene derivatives featuring smaller ligands that display enhanced formation of larger carbon clusters. However, the presence of the dendritic phenylacetylene ligand hindered reactive interactions between the fullerene entities, thereby completely preventing coalescence. © 2003 Elsevier B.V. All rights reserved.

Chlorinated [60]fullerenes which have been prepared by a variety of different synthetic methods have been studied by means of direct laser desorption/ionisation (LDI), matrix-assisted laser desorption/ionisation (MALDI) and desorption electron ionisation (DEI) mass spectrometry. The aim of this investigation has been the elucidation of the unusual signal sequence observed in earlier positive-ion MALDI experiments, which featured a spacing of 77 Da between the signals of fullerene-containing ions. Circumstantial evidence has been provided, which strongly indicates that the 77 Da correspond to a C6H5 (phenyl) ligand. The findings reveal that phenylated by-products that result from the use of benzene during synthesis may be of strong influence on the physico-chemical characterisation of chlorinated C60.

The distribution of small carbon clusters derived by laser ablation (laser desorption/ionization) of thin films of derivatised fullerenes has been studied. The production of positive and negative ions has been monitored by time-of-flight (ToF) mass spectrometry. The materials under investigation included the [60]fullerene (C 60 ), hydrogenated and deuterated [60]fullerenes (C 60 X 36 where X=H and D), fluorinated [60]fullerenes (C 60 F x where x =46 and 48) and the aza[60]fullerene dimer ((C 59 N) 2 ). Following laser ablation using a nitrogen laser, the efficient formation of small, negatively charged carbon clusters has been observed, while the corresponding positively charged clusters were not formed. Derivatised fullerenes display the co-formation of small binary carbon clusters of the type C n X − , where n shows odd/even alternation depending on X which represents the heteroatom initially linked to or networked with the fullerene cage. Although binary carbon clusters C n X − were formed where X=H, D and N, the ablation of fluorofullerene targets would not lead to the formation of C n F − clusters under the applied conditions, as confirmed by ablation experiments with chloro/fluoroalky-polymers. The formation of the binary carbon clusters has been also studied by laser fluence-dependent production of C n D − ions from C 60 D 36 , and by the production of C n P − ions using a composite C 60 /P 4 target. Possible pathways leading to small binary carbon clusters are addressed.

The cationic complexes of Pt(II), Pd(II) and Rh(III) with two water-soluble porphyrins: meso -tetrakis (4- N -methylpyridyl) porphyrin and meso -tetrakis (4- N , N , N -trimethylaminophenyl) porphyrin are easily and irreversibly immobilized in ion-exchange membranes (e.g. Nafion ® ). The phosphorescence of the metalloporphyrins inside the membrane is effectively quenched by molecular oxygen. The Stern–Volmer plots ( I 0 / I versus [O 2 ]) are linear over the entire range of oxygen concentrations (0–100%). High photostability, sensitivity and good response times indicate that cationic platinum metals porphyrins immobilized in Nafion ® membranes are promising sensing materials for oxygen analysis.

The results of in situ measurements of supercooling of the interface during the growth of Bi 4 Ge 3 O 12 single crystal from melt are presented. Supercooling was determined by measuring the intensity of intrinsic thermal radiation from the interface, which was recorded with an optical pyrometer through the growing crystal. The dependence of growth rate on supercooling was determined from the experimental data on supercooling versus the cooling rate for a thin layer of melt. The features of the determination of supercooling during the formation of macrosteps on the facet are considered. Experimental data are obtained concerning the dependence of growth rate on supercooling for crystal growth in the [2 1 1] direction. ( 2000 Elsevier Science B.V. All rights reserved.

The paper describes the results of experimental study of real time dynamic holographic correction of lens distortions in a model telescope, imaging a remote object in incoherent non-monochrome radiation in the visible range of the spectrum. Dynamic correction in the scheme of one-way imaging was provided by the thin dynamic hologram of the lens distortions, recorded in the optically addressed liquid crystal spatial light modulator.

Resonant electron capture spectra of C60F48 and its oxy-analogue C60F48O have been studied and interpreted. Long-lived parent negative ions are formed within a 0–8 eV energy range with a maximum yield at approximately 0.14 eV. Going from thermal energy and up to 8 eV, these parent anions undergo fragmentation with generation of even-numbered fluorine negative ions due to sequential loss of F2 down to C60F36− and C60F36O−, respectively; the yield of fragment anions at thermal energy rises with the degree of fragmentation. At approximately 8 eV and above, the odd-numbered fluorine fragment anions were registered. The formation of these anions in the energy range 17–45 eV was associated with the resonant state where the excitation of σ-plasmons is supposed to occur. The appearance energies of positive parent and fragment ions from C60F48 as well as parent C60F36+ have been measured. The parent ion C60F48− undergoes electron autodetachment at 3–4 eV with a mean lifetime in the millisecond scale. Estimations for CF bond dissociation energy and electron affinity of C60F47 are reported. Published by Elsevier Science B.V.

Imines 3–6 containing fluorinated N-substituents were prepared by reactions of fluorinated sulfinylamines 1, 2 with hexafluoro-acetone and ethyl trifluoropyruvate; trifluoromethylsulfonylimines 3, 5 exothermically reacted with dienes at –50 °C to form cycloaddition products 7, 9 and α-aminoalkylation products 8, 10.

Butadiene, cycloocta-1,5-diene and cycloheptatriene were found to form cycloaddition products with 2,5-bis(perfluoroalkyl)-1,3,4-oxadiazoles: 3-oxatricyclo[2.2.1.02,6]heptane, 7-oxatetracyclo[6.3.0.02,6.05,9]undecane and 6-oxatetracyclo[5.3.0.02,5.04,8]dec-9-ene, respectively. The structure of the last compound was confirmed by single crystal X-ray diffraction.

Correlations between the intersections of a film with a random plane are related by an integral transform to the film orientational correlations. For a wide class of the film orientational correlation functions we have derived the inverse transform, which determines corresponding weight functions for the statistical analysis of random sections. The inverse transform is found to be the Weyl fractional integral transform.

The picosecond transient absorption spectrum of C 60 in toluene was obtained in the region 420-1100 nm and a new transient absorption band near 1000 nm was discovered. This band was attributed to the S 1 —S x transition, probably between configurations (h u ) 9 (t 1g ) 1 ← (h u ) 9 (t 1u ) 1 . The intersystem crossing time τ= 830±190 ps was estimated from the S 1 —S x absorption decay and from the creation of the T 1 -T x absorption band.

The change in the optical absorption by a solute S when an admixture is added to the solvent is considered for a weak long-range interaction between S and the admixture particles S A . In the case of an approximately two-level absorption a closed formula of the variation of the optical absorption intensity due to the admixture is obtained. It can be directly used to deduce some information on the SS A interaction and also on the absorption mechanism.

A thermodynamic theory of the solvated electron in a strong electrolyte dilute solution is presented. A model of an electron state localized due to inertia polarization and Debye screening, is studied in various approximations. The effects of the ion-induced localization mechanism are discussed, involving in particular a blue shift of the solvated electron's absorption band with an increase in the ionic strength of solution.

A situation in which a finite set of players can obtain certain payoffs by cooperation can be described by a cooperative game with transferable utility, or simply a TU-game. A solution for TU-games assigns a set of payoff vectors to every TU-game. Some solutions that are based on distributing dividends are the Shapley value (being the single-valued solution distributing the dividends equally among the players in the corresponding coalitions) and the Selectope or Harsanyi set (being the set-valued solution that contains all possible distributions of the dividends among the players in the corresponding coalitions). In this paper we assume the players to be hierarchically ordered. We modify the concept of Harsanyi set to this context by taking into account this hierarchical order when distributing the dividends of the game. We show that the resulting new solution concept for games with ordered players, called the Restricted Harsanyi set, is fully characterized by a collection of seven logically independent properties. We also discuss an alternative modification of the Harsanyi set and a solution concept resulting from adapting the concept of Selectope to games with ordered players. Some applications show the usefulness of the Restricted Harsanyi set.

This paper reports on the realization of small area long-wavelength infrared (LWIR) photodiodes based on CdHgTe films grown by molecular beam epitaxy (MBE). The composition of the ternary compound is controlled in situ by a single-wave ellipsometer that offers the possibility to grow epilayers with a desirable composition profile across the film thickness. Photodiodes have a vertical configuration and have been fabricated using planar technology by annealing under an anodic oxide film.

In this paper we describe the extreme points of two closely related polytopes that are assigned to a digraph. The first polytope is the set of all sharing vectors (elements from the unit simplex) such that each node gets at least as much as each of its successors. The second one is the set of all fuzzy vectors (elements of the unit cube) with participation rates of players subordinated to the relationships prescribed by the digraph. We also discuss some applications in cooperative game theory.

The way the excess electron e s − or solvated halide ion X s − absorption band is transformed with an increase in the ionic strength of a dilute electrolyte solution is found. This transformation can give information about the mean charge densities of the e s − or X s − initial and final states.

Localized electron states in condensed media get stabilized when the concentration of movable ions increases. This effect may occur in liquid and solid electrolytes, as well as in biomacromolecules. We associate it with the solvated electron blue shift under increased ionic strength of the solution. We can suppose the existence of an electron state (“ionon”) localized only, or mainly, due to the atmosphere of movable ions.

A study has been made of the effect on the molecular weight and yield of polyesters of the chemical structure, concentration and order of introduction into the reaction zone of the reactants, and of the temperature and time of acceptor-catalytic polycondensation.

A study has been made of the extent to which low-temperature polyesterification reactions in the presence of triethylamine may be influenced by the type of solvent being used. It was found that while the solvent nature has no marked effect on the shape of ηred vs. T plots, it does influence the molecular weight of the polymer. High-molecular polyarylates were obtainable when the polyesterification was carried out in a metastable solution (a binary mixture of solvent and precipitant).

THE development of new methods for synthesizing new types of heat-resis tant p o l y m e r s t h e polyaryla tes (PA)-requires detailed s tudy of these s tructures and of the effects of var ious factors on them. One of the impor t an t elements of po lymer s t ructure is the porosity; it has a considerable effect on the mechanical , thermophys ica l properties, the water and gas permeat ion, etc. The work which is described here deals wi th the porous s t ructure of P A and the clarification of the effects of synthesis t empera ture and molecular weight (mol.wt.) on it.

A NUMBER of the basic re la t ionships in the synthesis of po lya ry l a t e F-2 t}om t e r e p h t h a l y l chloride a n d pheno lph tha le in in the presence of t r i e thy l amine arc now known [1, 2]. I t m a y be a s sumed t h a t the na tu r e of the correlat ions in lowt e m p e r a t u r e polyester i f ica t ion will va ry , depending on the chemical s t ruc ture of the reac tan t s . The purpose of the presen t work was to s t udy some correlat ions in the lowt e m p e r a t u r e po lycondensa t ion of t e r eph tha ly l chloride wi th b is (4-hydroxy-3ch lorophenyl ) -2 ,2-propane(d ich lorodiphenylo lpropane) , carr ied out in the presence of t r i e thy l amine , unde r bo th homogeneous and he terogeneous conditions. For the fo rmer the reac t ion m e d i u m was dichlorocthane, which dissolves the r e a c t a n t s and the po lyary la te . I n the la t te r case the organic med ium was acetone, in which only the r e a c t a n t s are soluble, the po lya ry l a t e being prec ip i ta ted .

In this work, Mossbauer spectra of wustite are studied in the temperature interval 600–910°C. Owing to self-diffusion of iron atoms in the defect wustite lattice, a pronounced broadening of the spectrum is observed. The values of the energy of activation and of the preexponential factor computed from the Mossbauer spectra amount respectively to 25 ± 3 kcal/g-atom and 0.6 × 10 −4 cm 2 /sec. The error for log D 0 equals ±0.8. These magnitudes are in satisfactory agreement with the values found by isotopic methods.