Mutual Transfer Research Articles

Luminescence in Na Ln(SO 4) 2H 2O: A host lattice with high-energy vibrations

The luminescence of Ce 3+, Sm 3+, Eu 3+, Gd 3+, Tb 3+, and Dy 3+ in Na Ln(SO 4) 2H 2O ( Ln = lanthanide) is reported. Only Ce 3+, Gd 3+, and Tb 3+ show efficient emission. This is explained in terms of an energy-gap law. Energy transfer is studied in several codoped compositions. The mutual transfer between Gd 3+ ions is the only one encountered with high probability. The several transfers are discussed and where possible their rates are calculated.

Investigation of Oxides Formed in the Corrosion of SUS-304 in High-Temperature Water Through the Measurement of Evolved Hydrogen and Radiochemical Analyses

Corrosion behavior of SUS-304 at 280/sup 0/C in deaerated water has been traced both through measuring H/sub 2/ gas, concomitantly formed with corrosion, and through radiochemical analysis of the corrosion layers. The calculated H/sub 2/ yield based on the reaction, M + x.H/sub 2/O = MO /sub x/ + x.H/sub 2/ (M: iron, chromium, nickel, manganese, and cobalt), agreed reasonably well with the observed H/sub 2/ yields, showing that iron is mainly in a magnetite form and chromium is in a Cr(III) state. More than 85% of the corrosion layers were recovered by repeating ultrasonic cleaning and electrostripping processes. The residual fraction was rich in chromium and dissolved in the subsequent electropolishing process. The total corrosion increases with the reaction time, although the ''inner layer'' tends to stay almost constant at a longer reaction time. In some cases, both neutron irradiated and nonirradiated SUS coexisted. Mutual transfer of the elements from one SUS to the other has been examined.

Luminescence and mutual energy transfer between erbium(III) and manganese(II) in fluoride glasses

Glasses of mixed fluorides, contrary to the glasses formed by more conventional anions(such as silicate, phosphate and borate) have much greater propensity for luminescence of the excited J-levels of trivalent lanthanides. A major reason is the low vibrational frequencies (attenuating the competing non-radiative de-excitation). The composition ranges of stable glasses are quite narrow, and found pragmatically. They are wider in the presence of small amounts of Al(PO 3) 3 but this decreases the life-times of Er(III). The two main types used for spectroscopic studies contain GaF 3 PbF 2 and ZnF 2 (which can be replaced by MnF 2); or ZrF 4 and BaF 2. Here, incorporated erbium(III) is discussed. The narrow emission bands at 550 nm( 4S 3/2) and 668 nm( 4F 9/2) have life-times above 0.05 ms. Energy transfer from the former level to the lowest quartet level of manganese(II), and back transfer of energy stored in Mn(II) to Er(III) providing long-lived components of the 668 nm emission, are also described. Such fluoride glasses containing Nd(III) or Er(III) may be important for lasers, fiber optics communication, and luminescent solar concentrators based on total internal reflection of emitted photons travelling to the edge of a transparent plate.

Friction, metallic transfer and debris analysis of sliding surfaces

The variation in the coefficient of friction with sliding distance for different sliding conditions for both similar and dissimilar metals in a crossed-cylinder geometry is presented. Metallic transfer due to adhesion at the early stage of sliding controls the coefficient of friction of a soft metal sliding on a hard metal. Debris generated in the wear process are formed of the soft metal only. For a hard metal sliding on a soft metal friction is influenced by the ploughing action. There is mutual transfer of metals between the sliding surfaces and the generated debris in this case are formed of both metals. These observations are confirmed by scanning electron microscopy and electron probe microanalysis.

Topographical features observed in a scanning electron microscopy study of aluminium alloy surfaces in sliding wear

Abstract Extensive examination of sliding wear surfaces was undertaken on various Al-Si alloys using the scanning electron microscope in an attempt to elucidate the prevailing mechanism or mechanisms of wear. Recurring surface features were noted which gave a positive indication of diverse mechanisms operating across the range of material composition and contact stresses involved. It is postulated that mutual transfer across the wear interface is an extremely significant feature of all regimes of sliding wear, becoming more prevalent in materials whose yield stresses are low or where normal contact stresses are high. Asperity interaction, gross layering and ductile fracture constitute the predominant mode for conditions bordering on seizure, whereas a shear transfer mechanism operates in regimes between those of mild and severe wear. Delamination producing wear craters is a predominant feature of mild wear regimes in eutectic and hypereutectic alloys, but primary and secondary modes dependent on subsurface and surface failure respectively can be recognized. The concept of mutual transfer suggests that pin surface topography is a function of material back transfer such that a new delamination mode can be recognized where failure results from surface-initiated cracks extending down to interlayer zones. Work on asperity macromodels using wax as the simulative medium provides strong evidence for an almost universal transfer mechanism.

An energy transfer equilibrium between two identical copies of a ribosome-bound fluorescent transfer RNA analogue: Implications for the possible structure of codon-anticodon complexes

When yeast tRNA Pf Phe, a derivative of tRNA Phe in which proflavine replaces the Y base, is bound simultaneously to both the peptidyl and aminoacyl sites of a 70 S Escherichia coli ribosome, there is a rapid mutual energy transfer between the two bound tRNAs. Analysis of this energy transfer yields an upper limit for the proflavine-proflavine distance of 20 Å. It also allows an unequivocal measurement of the emission spectrum of tRNA Pf Phe bound at the aminoacyl site. In the presence of message this spectrum is very different from that seen in the peptidyl site, implying that in the two sites the hypermodified bases exist in significantly different environments. The rapid energy transfer leads to some loss of fluorescence anisotropy. This can be analyzed to obtain an estimate of the angle between the two proflavines: 28 ° ± 10 ° or 152 ° ± 10 °. Taken together all of these results place severe constraints on possible models of codon-anticodon complexes. The mutual energy transfer seen and analyzed on the ribosome is a convenient aspect of fluorescence spectroscopy, and it is one that should see broad application where multiple copies of a fluorescent ligand interact on a macromolecular substrate.

Ce3+ Luminescence in Hexagonal Aluminates Containing Large Divalent or Trivalent Cations

By analogy with earlier studies on Eu2+ phosphors the luminescence of the Ce3+‐doped hexagonal aluminates, containing large, divalent or trivalent cations, was also studied in relation to the crystal structure of the host lattices. The u.v. band ascribed to the luminescence of Ce3+ ions is found at a relatively short wavelength in the magnetoplumbites Ca‐, Sr‐, and aluminate: Ce and at a relatively long wavelength in the β‐aluminas Ba‐ and aluminate. The distorted magnetoplumbites which include La‐ and aluminate and Ce‐ and aluminates themselves occupy an intermediate position in between the above‐mentioned groups. The existence of various types of host lattices is also reflected in the shape and position of the excitation spectra of the Ce3+ luminescence. Differences in bond strength between Ce3+ ions and its surrounding oxygen ions, however, complicate the discussion of the position of the excited 5d levels of the Ce3+ ion. Apart from the u.v. band, a blue luminescence band was found in several Ce‐activated aluminates. This band occurs in phosphors where oxygen ions are thought to have partially replaced the large cations of the host lattice and is ascribed to Ce‐O associates. Next to direct excitation of these centers, the u.v.‐emitting Ce3+ ions transfer part of their energy of the associates. If Mg2+ ions are present in the lattice, the oxygen ions at large cation sites seem to be “screened” and no blue luminescence is found. The quantum efficiency of most Ce‐activated aluminate phosphors is 50–70%. Due to ineffective mutual energy transfer between u.v. emitting Ce3+ ions and between Ce‐O associates no concentration quenching occurs in the systems considered. For the same reason the influence of the preparation method on the luminescence properties is generally less drastic than that of the corresponding Eu2+ phosphors.

Pendular and rotatory vestibular habituation

The present investigations demonstrate in animals (rabbits) the existence of a habituation to the vestibular pendular stimulation comparable to the rotatory habituation by constant angular acceleration. There is no mutual transfer, however, between the two habituations. This confirms that the two modes of stimulation are not equivalent. All the tests have been made by ENG recording in total darkness.

The reactivity of organophosphorus compounds. Part XXIX. Deoxygenation of nitroxyl radicals by trialkyl phosphites: a new route to nitrenium ions via electron transfer reactions of aminyl radicals

A convenient and mild route to arylnitrenium ions is described: deoxygenation of diphenylnitroxyl by triethyl phosphite in boiling ethanol under nitrogen gives diphenylamine and p-ethoxydiphenylamine. Thermolysis of tetraphenylhydrazine in ethanol gives the same product, thus pointing to the formation of diphenylaminyl radicals which, in part, undergo mutual electron transfer to give diphenylnitrenium ions. In accord with this phenyl-t-butylnitroxyl reacts with triethyl phosphite in methanol to give o- and p-methoxy-N-t-butylanilines in the same ratio as that produced via the authentic nitrenium ion route from N-chloro-N-t-butylaniline in methanol. Diphenylnitroxyl readily dehydrogenates 9,10-dihydroanthracene, the efficiency of the reaction being improved several fold by a cycle involving in situ regeneration of diphenylnitroxyl by aerial oxidation.

Partial reversions of a proline auxotroph of Salmonella Typhimurium Cross-feeding associated with cell-to-cell contact

• From the partial reversions of the proB401 auxotroph of Salmonella typhimurium, strains can be isolated which grow slowly in the presence or absence of proline. The slw phenotype (pro-S) cannot be transfered into proB401 either by transduction, or by conjugation from an Hfr pro-S donor, and when a pro-S strain is used as recipient with an Hfr donor all the recombinants are either proB401 or pro +. When pro-S trp − (tryptophan-requiring) and pro − trp + bacteria are plated together on minimal medium, on which neither strain will grow, colonies form which are a mixture of the two strains plated. The ability of the pro-S strains to participate in this mixed colony formation is genetically determined, can be selected, and is not influenced by the presence of F′ episomes. Wild-type, pro +, reversions do not behave in these ways. • It is proposed that the pro-S phenotype is due to a plasmid-linked suppressor mutation, and that the ability to form mixed colonies is due to a further mutation, also probably plasmid-linked, which can only act in combination with the suppressor and by itself has no observed effect; together, these mutations promote cell-to-cell associations and enable the mutual transfer of gene products, so permitting growth.

Diffusion phenomena on rubbing surfaces in relation to wear resistance

When steel parts are working under heavy-duty conditions, there is always a possibility of the formation of carbides on their rubbing surfaces as a result of decomposition of lubricants and subsequent reaction of carbon with the metal. This process is inevitably associated with local seizing and mutual material transfer. As a result, the carbide phase formed during friction betwen two steels of a different composition may differ from the adjacent material in respect to its content of carbide-forming elements. When strong carbide-forming elements are present in a steel with a friction-induced surface carbide layer, heating such a steel to relatively low temperatures leads to localized decarburization which, under certain circumstances, may reduce the wear resistance of steel. In a simple case of a binary alloy, the rate of decarburization depends on the affinity of the alloying element to carbon.

Some relationships between the emissivities of volumes and the coefficients of mutual radiative heat transfer between them

Formulas connecting the emissivities of contiguous volumes and the coefficients of mutual radiative heat transfer between them ate obtained. The formulas can be used in calculations of radiative heat transfer by zonal methods.

Space-time correlation theory for information-carrying signals

A theory is presented for the analysis and optimization of systems which process electromagnetic fields carrying information. The theory is thus intended for use primarily by communications and radar engineers. The definitions are motivated by a fundamental requirement that the input-output space-time mutual information transfer be a maximum. The theory can be applied to problems involving nonstationary and nonergodic processes in space and time. The technique proposed is particularly useful in the analysis and optimization of controlled systems carrying man-made information, such as radar and communications. System optimization is carried out by maximization of the trans-correlation function with respect to the variable parameters of the system. The transcorrelation function is a space- and time-averaged correlation function between the desired and the actual system outputs. The optimization technique is applied to the problem of an antenna embedded in a nonstationary medium, such as a hot plasma. The amplitude and phase shading of the array are the variable parameters chosen for optimization of the system, and medium effects, background (object) noise, receiver noise, etc., are considered.

Studies on the Binding and Function of Flavin Phosphates with Flavin Mononucleotide-dependent Enzymes

Abstract The binding and function of FMN, 3,6,7-trimethyl-9-(1'-d-ribityl)isoalloxazine 5'-phosphate (3-methyl-FMN),6,7-dichloro-9-(1'-d-ribityl)isoalloxazine 5'-phosphate (6,7-dichloro-FMN), and 6,7-dimethyl-9-(5'-hydroxypentyl)isoalloxazine 5'-phosphate (5'-hydroxypentyl-FMN) has been investigated with reduced nicotinamide adenine dinucleotide phosphate dehydrogenase and NADPH cytochrome c reductase from yeast, NADH oxidase from a pseudomonad, pyridoxamine phosphate oxidase from liver, and glycolate oxidase from spinach. Considerable variation has been observed in the quantitative behavior of the flavin phosphates with the differing apoenzymes through measurements of Vmax and Km or Ki. The earlier postulation that the 3-imino group of the isoalloxazine is primary point of attachment of the flavin phosphate to an FMN-dependent apoenzyme must now be modified, especially for the NADPH dehydrogenase (old yellow enzyme) which has been considered to be the prototype of flavin coenzyme-apoenzyme interaction. Present observations with 3-methyl-FMN indicate a lack of absolute dependence on the 3-imino group and suggest a rather diffuse interaction through mutual polarization or partial charge transfer between relatively large portions of the isoalloxazine structure and perhaps aromatic amino acid residues in the proteins. The generally better binding than function of 6,7-dichloro-FMN indicates that the relatively poor function of similar analogues may be expected with substituent changes in position 6 and 7 which are of the approximate size of methyl groups but through contribution to the electromeric structure of the isoalloxazine markedly change the oxidation-reduction potential. The optimal requirement for a full complement of secondary hydroxyl groups in d configuration on the side chain in position 9 is apparent from the generally decreased coenzymatic activity seen with 5'-hydroxypentyl-FMN. However, there is no absolute dependence on interaction of the enzymes with each secondary hydroxyl group of a flavin phosphate, but rather a steric relationship which favors proper disposition of coenzyme to apoenzyme.

A study of heavy metal-to-plastic friction duties and of the wear of hardened steel in the presence of polymers

Under heavy polymer-to-metal friction duties, modification of the contacting surfaces is of great importance. The first reason for this modification is transfer of the metal to the polymer surface and of the polymer on to the metal surface. The intensity of this process depends mainly on the relative hardness of the contacting materials, and on the natures of the gas phase and the liquid medium. Frictional copper plating of reinforced thermosetting plastics may occur with glycerin as the lubricant. In the absence of mutual transfer, passing from friction in the air to friction in a vacuum of about 10 −5 torr does not affect the friction duty. Therefore, when there is no transfer, the oxide layers on the metal surface do not play the determinative role they do in metal-to-metal friction. The second cause of modification of the metal and polymer surfaces are the thermal processes which, in the case of thermosetting resins and high-melting polymers, may be accompanied by thermal or thermo-oxidative degradation of the polymers with the formation of highly reactive low-molecular compounds. In the case of thermoplastics a surface film of the melt may form. This sets up conditions for fluid instead of dry friction, makes the friction coefficient vs. load dependence extreme in character, and renders the friction force independent of the load at high values of the latter. Some powdered thermoplastics display high anti-wear action under heavy steel-to-steel friction duties, this being related not only to their ability to withstand being squeezed out of the friction zones at high specific loads, but also to tribochemical processes.

大腸菌と赤痢菌の間に発現する線毛発現能の伝達について

Mutual transfer of the fimbriation from the fimbriate donor cells to the non-fimbriate recipient cells was demonstrated in the selected recipient hybrids from the crosses between E. coli and Sh. flexneri.In the recipient hybrids which have been transferred the ability of the fimbriation, there were shown some biological characteristics different from the parent recipient cells, from which the hybrids were originated, in addition to the alteration of the antigenic structure and the modification of sugar fermentation, which were transferred from the parent donor cells, the dissociation of the colony form was clearly observed.Further observations on the segregations of the hybrids presented an evidence suggesting that the transfer of the ability of fimbriation might be due to the genetic recombination of fimbriation controlling gene(s), probably episome-like in nature, and that the recipient fimbriate hybrids seemed to be heterogenous in genotype.

Statistical Characteristics of the Atmospheric Disturbances

The periods of the atmospheric phenomena are supposed to differ from each other according to their scales, e. g., there may be a positive correlation between the magnitude of scales and length of periods in the atmosphere.The purpose of this paper is to investigate the statistical characteristics of the atmospheric disturbances of various scales and further to find out the mechanism of mutual transfer of vorticity and kinetic energy of mean flow and disturbances. If we succeed in this attempt, the results obtained from are expected to be useful also for such a forecasting problem as numerical prediction. In the present study the following characteristics of the atmospheric phenomena are dealt with, that is, (1) the so-called “width of perturbations ”, (2) the stationarity of variations, (3) the spectral distribution of pressure and (4) the kinetic energy spectra, employing the 36 term harmonic coefficients calculated from the values of 500 mb level along 50°N, 45°N and 30°N latitude circles in the Historical Weather Maps. The periods subjected to analysis are January (1946,1949), May, June and July (1951).The results obtained are as follows. First the component waves of disturbances can be classified into three (or four) parts. Then let n and F(n) denote wave number and spectral function respectively. The motion of waves of small wave number is non-isotropic, oscillatory and moreover F(n)=const. Meanwhile the motion of waves of great wave number is isotropic, progressive and F(n) ∝ n-7/3 as expected. Further it may be concluded that the mean flow and the component waves of n=1,2 belong to the former and component waves of n=≤6 belong to the latter region. Accordingly the components of n=3, 4, 5 are considered to constitute the region of middle wave number in our case.Next, the energy spectra indicate three sources of kinetic energy in the atmosphere, i. e., mean flow, component wave of n=3 and of n=6 or 7.