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The curve connecting a librational frequency with temperature consists of two parts. The first, linearly dependent on temperature, is assigned to the ν 1-0 librational transition, which may be regarded, in first approximation, as a harmonic vibration. The second non-linear one, lies near the fusion point and is assumed to be the superposition of two effects; (1) anharmonicity of the 1-0 transition, and (2) the existence of a “multitransitional” process. In each of these two cases, a method for computing the anharmonicity coefficient x e of the molecular libration is suggested, and applied to the ν 5 Ag ( u ) librational mode of paradibromobenzene.

Excitation functions for the reactions 40Ar + 144Sm → Pt and 40Ar + 166Er → Po radionuclides, in which the observed nuclei have two protons less than the product of the complete fusion of projectile and target, have been found to be characterized by two peaks. Independent of whether the target was Sm or Er, and independent of the mass of the product, the two peaks were consistently found to be separated by ≈ 40 MeV of excitation energy. Consideration of other experiments with 40Ar ions, and with lighter projectiles, leads us to the conclusion that the two peaks are due to different compound-nuclear de-excitation processes: the first peak involves the evaporation of an α-particle, (Ar, α(x − 2)n), and the second peak, the emission of nucleons only, (Ar, 2pxn).

Fission and complete-fusion cross sections are presented for four entrance channels leading to $^{170}\mathrm{Yb}$ compound nuclei excited to 107 MeV: $^{11}\mathrm{B}$ + $^{159}\mathrm{Tb}$, $^{12}\mathrm{C}$ + $^{158}\mathrm{Gd}$, $^{16}\mathrm{O}$ + $^{154}\mathrm{Sm}$, and $^{20}\mathrm{Ne}$ + $^{150}\mathrm{Nd}$. The measured fission cross sections are 5.9 \ifmmode\pm\else\textpm\fi{} 0.6, 16. \ifmmode\pm\else\textpm\fi{} 2., 40. \ifmmode\pm\else\textpm\fi{} 4., and 89. \ifmmode\pm\else\textpm\fi{} 9. mb for the $^{11}\mathrm{B}$, $^{12}\mathrm{C}$, $^{16}\mathrm{O}$, and $^{20}\mathrm{Ne}$ entrance channels, respectively. The completefusion cross sections for these same entrance channels are 980 \ifmmode\pm\else\textpm\fi{} 150, 1100 \ifmmode\pm\else\textpm\fi{} 160, 1260 \ifmmode\pm\else\textpm\fi{} 190, and 1450 \ifmmode\pm\else\textpm\fi{} 220 mb. The data are combined using a technique which yields the dependence of fission probability over three relatively narrow ranges of angular momentum. The results of the analysis just described are compared to a calculation based on the Bohr-Wheeler formalism for fission widths and the Weisskopf formalism for neutron and charged-particle widths. The calculations include the effects of multiple chance fission but assume that second and higher chance fission is nonnegligible only if preceded by neutron emission rather than charged particle emission. Agreement between the experimental results and the theoretical calculations is found for a ratio of level density parameters for the compound nucleus and the saddle point equal to 1.2 \ifmmode\pm\else\textpm\fi{} 0.1. Fission-fragment angular distributions for the four entrance channels are presented and compared to calculationsNUCLEAR REACTIONS, COMPLETE FUSION, FISSION $^{159}\mathrm{Tb}$($^{11}\mathrm{B}$, $^{170}\mathrm{Yb}$*), $E=115$ MeV; $^{158}\mathrm{Gd}$($^{12}\mathrm{C}$, $^{170}\mathrm{Yb}$*), $E=126$ MeV; $^{154}\mathrm{Sm}$($^{16}\mathrm{O}$, $^{170}\mathrm{Yb}$*), $E=137$ MeV; $^{150}\mathrm{Nd}$($^{20}\mathrm{Ne}$, $^{170}\mathrm{Yb}$*), $E=144$ MeV; measured $\ensuremath{\sigma}(\ensuremath{\theta})$ for evaporation residues and fission fragments, deduced ${J}_{\mathrm{CRIT}}$, ${\ensuremath{\Gamma}}_{f}$.

In an earlier work [l] we have demonstrated the local nature of fusion of elements in a Sylow p-subgroup P of a group G. We showed that if x and y are elements of P which are conjugate in G then there is a sequence of elements x1 ,... , e~‘n of P such that x = x1 , y = x, and each pair xi, xifl is contained in a subgroup Hi of P and are conjugate in N(H,). The elements xi, xifl are said to be “locally conjugate” and so every conjugation is the result of a sequence of local conjugations. Previously, we gave great details about the nature of the subgroups Hi that could be used and of the elements of N(H,) which performed the actual conjugation of xi to X~+~ . However, in this sequel, it is the actual sequence xi ,..., x,~ that we shall see can be chosen in a very special way. This result is of use in proving that certain elements of P are not conjugate in G. We shall give an example of this at the end of this paper but the main applications will come in later work. Let us now state the main theorem in its simplest form. After proving this version of it we shall examine our proof and be able to state and digest the final form of our main result.

This is a survey of the work done at Orsay on the accelerator ALICE, on reactions induced by very heavy ions. (Ar to Kr). It deals mainly with the questions of complete fusion and very inelastic exchanges of nucleons which are relevant to the problem of nuclear viscosity. New results are presented on the very inelastic processes which produce light fragments in Ar-induced reactions on Ni and Th targets. The angular and mass correlation has been verified between the light and the heavy partner, and it is now entirely proven that a large amount of energy is dissipated into intrinsic excitations. Measured cross sections for complete fusion are compiled and a number of comments are given on the limitation for fusion in relation to critical angular momenta and critical distances of approach. For reactions induced by krypton and copper ions, the fusion barrier is higher than the interaction barrier. Below the fusion barrier, peculiar phenomena occur, named “quasi-fission“. The fusion barrier is explained in terms of a cut-off in the low Ifi population for partial waves of the incoming ion, due to friction forces. 1. Partial wave decomposition. Complete and incomplete fusion In the frame of the well known description of nuclear collisions in terms of partial waves, heavy ion induced reactions may be classified [l] in three categories, as shown in Fig. 1. The magnitudes of the categories vary strongly with the incoming energy and with the mass of the projectile. (i) For the few highest I values, i.e., for soft grazing trajectories corresponding to the “rainbow angle” of the semi-classical theory, a quasi-elastic process induces transfer reactions in which a small number of well defined nucleons are exchanged with typical selection rules. This mechanism provides a good tool for microscopic studies of nuclear structure and has been exploited extensively.

1. Within the framework of the model presuming a triangular cross section of the drop, the kinetic equation of the fusion of two drops on a solid surface was obtained, satisfactorily describing the experimental data, and the best agreement is observed for low temperatures, low values of the initial height of the drops, and high values of the height of the neck z, i.e., for low rates of fusion. 2. The ratios of the surface tension to the viscosity of the substance σ/η calculated from the equation of fusion for all temperatures are close to the values of σ/η obtained on the basis of the literature data. 3. The rate of fusion increases with increasing temperature and initial height of the drop, and this effect is manifested to the greatest degree in the initial period of the process. 4. The close values of the apparent activation energy of fusion and viscous flow show that fusion proceeds according to a mechanism of viscous flow.

The use of intense laser light to bring about thermonuclear reactions in a plasma is of considerable current interest. We present detailed analytical and computational studies which show the feasibility of laser-driven fusion. The required laser technology and the presently anticipated practical difficulties are discussed in outline.

It is shown how Lawson criterion for controlled fusion might be achieved by magnetic compression of intense ion rings to field reversal.

The lineariled eluations describing non-isothermal, steadl-state dendritic grolth are solved numericalll, and the grolth rate-supercooling relation ascertained. For small supercoolings, the grolth rate-supercooling relation is sholn to be V = 0.064( 2α l ΔS f L γ sl c l )( ΔT/L c l ) 2.65 lhere V is the grolth rate; ΔT is the supercooling: ΔS f is the entropl of fusion per unit volume: L is the latent heat of fusion; γ sl is the solid-liluid interfacial free energl; and α l and c l are the thermal diffusivitl and specific heat of the liluid, respectivell. The theoreticalll predicted grolth rates agree lith those predicted bl the “modified Ivantsov” anallsis at high supercoolings and are higher than those predicted bl the Bolling-Tiller-Temkin approach (bl a factor of 2.3 at lol supereoolings).

Summary Cell fusion of Ehrlich ascites tumour cells caused by antigen-antibody complexes of Sendai virus was studied by electron microscopy. The fusion process was similar to that produced by virus. The fusion of envelopes of virus particles aggregated by antibodies and cell membranes was not observed under the conditions employed, though cell fusion was enhanced. This finding supported the hypothesis that the formation of cell-cell bridges but not of cell-envelope-cell bridges is involved in the initiation of cell fusion.

A method of preparation of homogeneous glass beads by direct fusion of bulk rock powders on an iridium-strip heater, and the quantitative analysis of these glasses using an electron microprobe fitted with an Si(Li) detector, are described. Major element concentrations obtained for international geochemical reference standards are of high precision, and agree well with recommended values obtained by other methods.

The fragmentation of a nuclear system is described by a dynamical coordinate, the fragmentation coordinate η=A1−A2/A1+A2 The total Hamiltonian describing a binary heavy ion encounter includes a part H(R, α,η) which describes the fragmentation and its coupling to other degrees of freedom. It is a collective Hamiltonian which is calculated from the microscopic Asymmetric Two-Center Shell Model (ATCSM). The properties of this Hamiltonian are extensively discussed and methods for its solution are described. Formulae for cross sections of specific nuclear fragmentations including fusion are derived.

Fusion from within (FFWI) by Newcastle disease virus occurs optimally in medium maintained at pH 8.2, whereas fusion from without is relatively insensitive to the pH of the medium in the range of 7.0 to 8.3. The pH-sensitive events in FFWI take place in the synthesis of the hypothetical fusion factor rather than in the response to it. pH pulse and pH shift experiments have localized the pH-sensitive events between 4 and 6.5 h postinfection (a period of synthesis of proteins required for FFWI), but before the fusion process. The pH sensitivity is not due to a pH-sensitive interference phenomenon. Virus production and the appearance of hemadsorbing cell surfaces are also pH sensitive, but for these functions the pH optima depend upon the virus strains tested. The independence of FFWI, hemadsorption, and virus production is discussed. Also discussed are the possible roles of virus-specific proteins in the fusion process.

Summary An assay system for fusion activity of envelope particles of Sendai virus, reassembled from NP40-solubilized envelopes, was established and conditions for the artificial assembly of NP40-solubilized Sendai virus envelope particles with haemolytic and fusion activities were investigated. Large (GP1) and small (GP2) glycoproteins and lipids seemed to be required for the expression of haemolytic and fusion activities of envelope particles. Potential haemolysin activity was associated with GP2. A relatively high proportion of GP1 was required for formation of envelope particles with a high fusion activity. When the top lipid fraction (Hosaka & Shimizu, 1972a) was used for reassembly, the envelope particles usually exhibited both fusion and haemolytic activities but the optimal concentrations of the lipid for the two activities were different. An unidentified factor extractable with NP40 seemed to be necessary for fusion activity but not for haemolytic activity.

The decreased growth rate observed in older muscle cultures has been attributed to the withdrawal of cells from the proliferative pool by fusion. The possibility was examined that this decrease reflects changes in the cell cycle as well. Before fusion, the cycle is relatively short and uniform (10.0 ± 2.7 hr) becoming greatly extended and more variable (19.2 ± 8.5 hr) in cultures undergoing fusion. Most of the increase in generation time is introduced by a long, variable G 1 phase, that phase to which fusion is restricted. These stage-specific cycle characterstics are a function of changes occurring in the medium, rather than of time in culture. Older cultures, refed fresh medium acquire the cell cycle characteristics of younger cultures, and conversely, early cultures fed medium collected from older cultures exhibit cycle measurements typical of older cultures. Although the mean G 1 time almost doubles at the time of fusion, there is no evidence that cells actually withdraw from the cycle prior to fusion. Continuous labeling before and after the initiation of fusion indicate that at all stages virtually 100% of the mononucleated cells incorporate 3 H-TdR. Since fusion occurs in G 1 , it seems reasonable to assume that some preparation for fusion occurs during this phase and the probability of fusion increases with protraction of G 1 .

The fusion of heavy nuclei is analyzed in a classical potential model. A quasi-elastic two-body potential is derived from the liquid drop model with inclusion of a finite range of interaction. Energy and angular momentum dissipation by friction are considered in the limit of strong localisation at the point of contact. The model suggests a classification of fragment pairs in terms of the parameter x = (e 2 /r 0 a s )Z 1 Z 2 /A 1 1 3 A 2 1 3 (A 1 1 3 +A 2 1 3 ) . The conseque of the model are discussed in detail. It is shown that a large body of data on fusion barriers and fusion cross sections can be reproduced. Predictions are made for heavier systems and higher energies than have been accessible so far.

Dynamic differential calorimetry has been employed to evaluate the heats of formation, heats and entropies of fusion of REIn 3 and RETl 3 compounds. The results obtained have been estimated to be corrected to within ±5–6%. The general trend, for both these series, is a decrease in the heat of formation from La to Lu which is correlated with the magnitude of the lanthanide contraction in these compounds. A simple correlation has been found between the heats of formation of REX 3 compounds and the ionic radii of the elements involved.

A system has been developed for the in vitro development of chick skeletal muscle monolayers, in which a burst of synchronous fusion occurs, such that some 40% of the spindle-shaped cells fuse in a 10-hr period. Cells inhibited from synthesizing DNA by ara-C do fuse, but at a later time than the normal burst. If ara-C is added to cultures 6 hr or more before the normal fusion time, fusion is delayed, but no delay results when the drug is added after this time. A medium change will delay the fusion if done 4 hr or more before fusion, but gives no delay if done later. Cells grown in conditioned medium fuse some 10 hr earlier than controls, even in the presence of ara-C, as do cultures prepared at higher than normal cell densities. The data suggest that muscle cell fusion is independent of DNA synthesis in vitro , but depends upon a modification of the culture medium to a sufficient degree required for initiating the synthetic program for fusion.

Summary: Fusion of Plasmodia of strains 15 and 29 of the myxomycete Physarum polycephalum under appropriate conditions results in a lethal reaction visible to the naked eye. Examination by autoradiography and electron microscopy of areas in which the reaction is occurring shows that most of the nuclei derived from strain 29 (the sensitive strain) are enclosed in vesicles and are disintegrating, but that almost all those originating from strain 15 (the killer) are healthy. At this stage other organelles appear to be undamaged. These results support the view that the essential feature of the reaction is the elimination of the nuclei of the sensitive strain and that the ultimate destruction of large areas which occurs under a limited range of experimental conditions is a secondary effect which may not occur in nature.

The growth rate of anorthite crystals from the melt is studied as a function of temperature with undercooling in the ranges 52-152 and 402-652 degrees C. The triclinic form is invariably observed as the crystallization product, growth is preferentially in the c direction, and the interface morphology is faceted. Significant growth rate anisotropy is indicated. The maximum growth rate of anorthite from the melt is higher than for anorthite-rich lunar compositions. Recent computer studies are combined with experimental data to estimate the heat of fusion of anorthite as 28000-45000 cal/mol; the corresponding range for entropy of fusion is (7.8-12)R (where R is the gas constant). The observations and kinetic data support Jackson's predictions concerning materials with large entropies of fusion and his suggestion that entropy of fusion is an important parameter for characterizing the crystal-liquid interface and the nature of the crystallization process.

In freeze fracture of the Tetrahymena fusion rosetts, the fracture can pass to either side of an intercalated particle by a stochastic process, dependent only on relative bond strength to either side of the intercalation. Any given freeze fracture particle can be found on either the A or B fracture face, with a chance measured by the particle partition co-efficient (Kp).

Description of a semiquantitative technique for predicting the segregation characteristics of smooth interfaces between binary solid and liquid solutions in terms of readily available thermodynamic parameters of the bulk solutions. A lattice-liquid interfacial model and a pair-bonded regular solution model are employed in the treatment with an accommodation for liquid interfacial entropy. The method is used to calculate the interfacial segregation and the free energy of segregation for solid-liquid interfaces between binary solutions for the (111) boundary of fcc crystals. The zone of compositional transition across the interface is shown to be on the order of a few atomic layers in width, being moderately narrower for ideal solutions. The free energy of the segregated interface depends primarily upon the solid composition and the heats of fusion of the component atoms, the composition difference of the solutions, and the difference of the heats of mixing of the solutions.

An analysis of the influence of the batch composition on the fusion and the spinel properties showed that fusion of alumina—magnesite mixtures proceeds satisfactorily with 35–50% magnesite but is troublesome with a larger or smaller proportion of magnesite.

It is known that the fusion rate of rigid PVC in an extruder partly depends upon the lubricants that are used. In the present study it is shown that different stabilizers have a great influence upon the rate of fusion of rigid PVC. Results from extrusion experiments and the Brabender Plastograph strongly indicate that a correlation exists between rapid melting in the extruder and the melt viscosity-temperature relation of the polymer blend. The reason why certain stabilizers cause a more rapid fusion of the PVC is attributed to the chemical structure of the stabilizers.

During Sendai virus-mediated fusion of mouse ascites cells, there is a loss of intracellular metabolites; at the same time accumulation from the medium is inhibited. This failure to maintain selective permeability does not occur at 0°C; it is unaffected by cytochalasin B, which inhibits fusion. It therefore represents a discrete, temperature-dependent event and may result from a weakening in membrane architecture necessary to achieve fusion.

The kinetics and shape of crystal growth from melt were studied for some organic substances (cyclohexanol, succinonitrile) and metals (Fe, Ni) with low entropies of fusion ( L / kT

Summary A method for induction of high aggregation and fusion frequency is described. About 10% dinucleated fused protoplast were obtained if Daucus carota protoplasts from a normally dividing cell suspension in protoplast growth medium were treated in a final concentration of 28% (w/w) polyethylene glycol at 25°C. The influence of salt composition and concentration on protoplast aggregation and fusion was studied as well as effects of different temperatures, pH and protoplast age and condition. Light- and electron micrographs show the strong adhesion and fusion of cell membranes and the osmotic changes in the protoplasts induced by polytehylene glycol.

Fusion excitation functions for /sup 32/S induced reactions on /sup 24/ Mg, /sup 27/Al, /sup 40/Ca and /sup 58/Ni are reported at incident /sup 32/S ion ene rgies of 65 to 132.5 MeV. Measurements were made using counter-telescopes with beams from Van de Graaff accelerators. From these data barrier heights and radii for fusion are extracted. These results are interpreted in terms of the nuclear diffuseness, and the nuclear attractive potentials at the fusion radii are deduced. Relative density overlaps at the fusion radius are estimated from electron scattering denslty distributions. Several parameterizations for the fusion radii and barrier heights are presented. Fusion cross sections are compared with reaction cross sections based on elastic scattering measurements coupled with optical model analysis. It is found that for the systems investigated, 90 plus or minus 10% of the reaction cross section results in fusion. (auth)

The equilibrium spreading pressures (πe) of a series of glycerides and phospholipids have been determined at various temperatures. Pure mono, di- and triglycerides and phosphatidylethanolamines can spread spontaneously from the crystal to form monomolecular films at the air—water interface, whereas phosphatidylcholines (lecithins) only spread from the liquid-crystal (i.e., at temperatures above the crystal or gel to liquid crystal transition temperature, Tc). Film pressures of up to 50 mN m−1 can be attained. Glycerides and phosphatidylcholines form liquid expanded monolayers in equilibrium with the bulk lipid while phosphatidylethanolamines can form both condensed and liquid expanded films. Liquid expanded monolayers are stable with respect to the bulk, lipid phase when π πe leads to collapse and formation of bulk, lipid phase without significant overcompression. Condensed monolayers of phosphatidylcholine are metastable (πe = 0 when T < Tc) and significant overcompression is observed before collapse to the gel or the monohydrate occurs. The equilibrium spreading pressures increase linearly with temperature until changes in physical state of the bulk lipid occur. On fusion or transition to a liquid crystalline state, the temperature coefficient of the equilibrium spreading pressure changes sign. The enthalpies and entropies of spreading are used to gain information on the structure of the lipid monolayers. The entropy of spreading and thus the order in the resulting monolayer is about midway between that of the crystal and the melt, depending on whether the compound spreads to a condensed or liquid expanded monolayer.

For a laser-driven fusion plasma dense enough to absorb the fusion particles, the slowing down of the reaction products and of their cascade of recoils is calculated (treating discrete energy loss in a collision correctly). The occurrence of reactions between the slowing-down particles and ambient ions is also calculated. The products of these reactions are in turn followed, through as many iterations as necessary. Illustrations are given.

The high temperature enthalpies of high purity ScF3, CeF3, SmF3, GdF3 (redetermined), TbF3, DyF3, ErF3, TmF3, and YbF3 were measured from 100 to 1600°C and EuF3 from 100 to 975°C. The thermal data for the other fluorides in the rare earth series were reported earlier from this laboratory. The heat capacity, enthalpies of transition and fusion, and related thermodynamic functions were calculated. The smoothed values of H°T−H°298.15, Cp, S°T−S°298.15, and −(F°T−H°298.15)/T are tabulated at 100° intervals. The melting points, transition temperatures, and lattice parameters of the high purity fluorides prepared in this study were determined.

Results are given for measurements of complete fusion cross sections in 40Ar and 84Kr induced reactions on medium and heavy targets. After complete fusion, composite nuclei decay by particle and gamma ray emission and also, in large proportions, by binary fission. Cross sections were measured on the residual nuclei and on binary fissions following full momentum transfer. In the case of Ar ions, the fusion cross section is still a large part of the total reaction cross section and the restriction due to high angular momentum is not severe. With krypton projectiles there is also a large proportion of complete fusion if the compound nucleus is in the medium masses. On the other hand with targets of bismuth and uranium a very small cross section was observed for fission events following a fusion process. An intermediate situation was found in the case of holmium and tungsten targets. Most of the reaction cross section goes into incomplete fusion channels, with a large loss of kinetic energy. A discussion is given on the dynamical aspects of the collision between two heavy nuclei.

The nucleoli are assumed to be originally of negligible size and located at random in the nucleus, considered as a sphere. They increase to a maximum size during interphase. Fusion occurs if the nucleoli touch during the size increase process. The probability of this event is calculated for various values of the maximum size of the nucleolus as compared with the size of the nucleus. A set of experimental data is analysed, using the results obtained. It turns out that the frequency of fusion is significantly higher than the assumption of initial random location would indicate. For further details on experimental material and methods, see Darvey & Driscoll (1972).

The catalytic decomposition of KClO4 by Fe2O3, obtained by calcination of Fe(II) salts at different temperatures, was investigated by DTA, TG, X-ray and IR. A sample without catalyst was found to begin fusion and decomposition simultaneously, and to form an intermediate, KClO3. Addition of catalysts resulted in solid-phase decomposition before fusion of KClO4, and in a small amount of KClO3. The difference in catalytic effect observed for different catalysts was less in the molten-phase decomposition than in the solid phase. The initial decomposition temperature (T i) increased with the temperature of preparation of the catalyst and showed a definitive relationship with the crystallite size of the catalyst. The change ofT i is discussed on the basis of then-type semiconductive properties of the catalyst.

The physics problems remaining to be solved to achieve practical fusion power by magnetic confinement techniques are believed to be well posed and soluble. A programme plan recently developed in the United States calls for progressively larger plasma confinement experiments to address these physics questions in line with a serious programme in fusion power engineering. Implementation of the plan is expected to lead to the first production of power from a deuterium–tritium-fuelled system in 1980. Thereafter, three progressively larger experimental electrical power reactors are planned, leading to fusion power commercialization in the later 1990s.The environmental characteristics of fusion reactors have been estimated by analyzing conceptual reactor designs. It is projected that the only volatile radioactive material in a fusion power-plant will be the tritium fuel. Analyses indicate that tritium leakage can be held to very low levels and accordingly should not pose a significant environmental hazard.Careful selection of the materials of construction of a fusion reactor core will minimize radioactivity induced by neutron activation. This activity will be nonvolatile, and it can be isolated from the environment by the use of existing techniques. Because this induced activity is short-lived, it does not represent a long-term storage problem.Anticipated thermal efficiencies of fusion powerplants range from present-day levels (30–40%) using standard conversion systems to about 50% when more exotic techniques (such as liquid-metal topping cycles) are utilized.