ALBERT

Notes: Summary A number of cut-off processes are investigated, with the Alpine region in most cases lying at the margins of these upper lows. Our aim was to determine whether the thermal front parameter (TFP) can be used to objectively define the areas of bad weather from analysis charts and prognostic charts. An attempt is made to formulate two synoptic “guidelines”, for the eastern Alpine region, on front-sides and northern margins of upper lows, into objective synoptic rules.

Notes: Summary This study examined ECMWF operational analyses of the outflow layer of two tropical cyclones (Allen, 1980; Elena, 1985) during their passage across the Atlantic and Caribbean. Wind fields and related derived quantities were compared to those from objective analyses of specialized data sets. Errors in center position and storm motion from the ECMWF analyses were also evaluated. Analyses of wind and angular momentum flux in 1985, subsequent to upgrading of the operational model, were superior to those from 1980. High-resolution, uninitialized analyses from 1985, however, provided no advantages over lower resolution, initialized analyses for the same time period. For all ECMWF analyses, azimuthally averaged (mean) tangential velocity, and thus mean vorticity, were well represented. Mean radial velocity and mean divergence were poorly represented. Problems with the latter arose primarily due to underestimation of outflow, especially in the 1980 analyses. Azimuthaleddy fluxes of angular momentum in the ECMWF analyses quantitatively differed from but qualitatively resembled, the control analyses. Vorticity maxima at 850 mb in the operational analyses most accurately defined the center position of the storms, with a mean error less than or equal to one grid point. In contrast, surface pressure minima failed to provide reliable estimates. Over open ocean and at early stages of storms, analysis quality was uneven, with occasional large position errors and widely varying locations of vorticity maxima in the vertical. Nevertheless, in regions surrounded by even a few rawinsondes, such as the Caribbean or Gulf of Mexico, ECMWF analyses contained sufficient information to allow individual case studies of the tropical cyclone environment. In the same regions, estimates of the eddy flux convergence of angular momentum were found to be accurate enough to aid in operational hurricane intensity prediction. Enhancements in resolution and model initialization at ECMWF since 1985 should further improve operational analyses of the tropical cyclone environment.

Notes: Summary This paper describes the evolution of two thunderstorms which developed over northeastern Colorado on 23 July 1983, and more significantly discusses the possible causal relationship between them. In particular, a disturbance apparently created by the first thunderstorm, which developed over the eastern slopes of the Rocky mountains, seems to have triggered the second thunderstorm, which developed further east over the high plains. We present evidence that suggests that the disturbance is a rapidly propagating gravity wave (possibly a solitary wave of depression) that occupied most of the troposphere and was generated by the explosive convective development of the first thunderstorm. Detailed observations of the interactions between these two storms were possible because both storms developed over a dense network of automated weather stations that provided high temporal and spatial resolution surface measurements of pressure, temperature, precipitation, and horizontal wind velocity. Also located within this mesonetwork was a high power 915 MHz wind profiler that provided radial velocities throughout most of the troposphere. These measurements were supplemented with GOES visible and infrared satellite imagery and operational data from National Weather Service rawinsondes and weather radars.

Notes: Summary Problems of turbulent dissipation of a cold air lake (CAL) and the inversion layer bordering CAL on the upper boundary are presented and studied with the compound model. In wintertime such cold air lakes can persist for days even if rather strong winds are blowing above them. The required conditions for CAL dissipation are removed processes of its formation or maintenance, as well as a sufficiently strong invasion of turbulence in the inversion layer from above down-wards. By this, the inversion layer at first becomes stronger and dissipation is stopped, until the increase of turbulent kinetic energy of the upper flow enables further dissipation. Such turbulent dissipation process is shown by the model for typical conditions and for different initial values of the relevent variables.

Notes: Summary THETAPLOT is a diagram useful for the display and analysis of atmospheric thermodynamic soundings, particularly in relation to conditionally and convectively instable summertime weather situations. The basic coordinates of THETAPLOT are the equivalent potential temperature and the negative logarithm of pressure. The body of the diagram contains families of curves of constant potential temperature, mixing ratio and temperature. From any given sounding, three curves are plotted on the diagram: 1) Theta-ed, the equivalent potential temperature of air saturated at its dew point temperature; 2) Theta-e, equivalent potential temperature; and 3) Theta-es, the saturated equivalent potential temperature. The winds are plotted along the margin of the diagram.

Notes: Summary This paper is concerned with the simulation of deep convection for the CCOPE 19 July 1981 case study. Clark's three-dimensional (3D) cloud model modified to use the bulk water parameterization scheme of Lin et al. has been used in the simulation of the CCOPE 19 July 1981 case in coarse mesh, fine mesh, and interactive grid nested schemes, respectively. Comparisons with observations show this 3D grid nested cloud model is capable of both capturing both the dynamic and microphysical properties of the cloud. In the nested grid fine mesh model simulation, the timing and mode of cloud growth, the diameter of liquid cloud, the cloud top rate of rise, the maximum cloud water content, and the altitude of first radar echo are consistent with observations. The simulated thunderstorm begins to dissipate, after precipitation reaches the ground as indicated by the decreasing values of maximum updraft and maximum liquid cloud water content, and ends as a precipitating anvil as was observed in the actual thunderstorm. The model precipitation developed through ice phase processes consistent with the analysis of observations from the actual thunderstorm. Qualitative comparisons of the actual radar RHIs with simulated reflectively patterns from the 3D model show remarkable similarity, especially after the mature stage is reached. Features of the actual RHI patterns, such as the weak echo region, upshear anvil bulge, strong upwind reflectivity gradients, and the upwind outflow region near the surface are reproduced in the simulation. Comparison of the actual radar PPIs with horizontal cross sections of radar reflectivity simulated by the 3D model, however, show modest differences in the storm size with the 3D simulated thunderstorm being 1–2 km longer in the west-east direction than the actual thunderstorm. The model-predicted maximum updraft speed is smaller than the 2D model-predicted maximum updraft speed, but still greater than what was observed. Comparisons among the nested grid fine mesh model (MB), nested grid coarse mesh model (MA), fine mesh model (FM), coarse mesh model (CM), and 2D model results previously published show that the nested grid fine mesh model (MB) gives the best simulation result. The various 3D model simulation results are generally similar to each other except for the difference in the domain maximum values. The domain maximum values in the fine mesh models (MB and FM) are generally higher than the coarse mesh models as a result of averaging over a smaller area.

Notes: Summary The Penn State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model is a widely used research tool that has been applied in a wide variety of real-data, mesoalpha-scale applications. Recently a nonhydrostatic version of this model has been developed by Dudhia (1993). It is the purpose of this paper to illustrate the capabilities of this modeling system by describing four examples of mesobeta-scale simulations: two of the cases involve maritime processes and two deal with continental weather events. All utilize fully three-dimensional sets of initial conditions that are based on real data, both standard data and from special measurements programs. One case employs the model in a data-assimilation configuration, wherein Newtonian relaxation terms are used in the equations to assimilate data from a variety of platforms. This example of nonhydrostatic four-dimensional data assimilation (FDDA) is performed for the purpose of generating a dynamically consistent four-dimensional data-set, however the same procedure can be used for model initialization. The first case, described in section 2, involves the simulation of a coastal front that forms offshore near the western edge of the Gulf Stream. In the second case, described in section 3, the model is used in the FDDA mode to define the mesobeta-scale windfield over the complex terrain of the region around Grand Canyon, Arizona. In sections 4 and 5 will be described the mesobeta-scale structure of cold fronts, one within a marine cyclone, and another near the Rocky Mountains.

Notes: Summary Hydrostatic and nonhydrostatic simulation models are employed to study the intensification of a terrain drag-induced dryline. The study develops a multi-stage theory for the evolution of the dryline including the concentration of potential vorticity accompanying meso-gamma scale dryline “bulges”. The numerical simulations indicate three fundamental stages of dryline intensification all of which are either directly or indirectly a result of the terrain-drag on the mid/upper-tropospheric jet stream by the Front Range of the Colorado Rocky Mountains. The first stage involves the downward momentum flux accompanying a large amplitude hydrostatic mountain wave which induces a downslope windstorm along the lee slopes. The surge of momentum (i.e., the dry, warm air associated with the downslope windstorm) propagates down the leeslope and modifies an existing weak dryline boundary. As the downslope windstorm initiates an undular bore along the lee slopes, the high momentum gradient which propagates downstream accompanying the bore, as well as the strong lower tropospheric sinking motions ahead of the bore, contract the scale of the surface moisture boundary between the dry air from above the leeslope and the moist air over the High Plains. This process further strengthens the dryline. The second stage involves the coupling of the terrain drag-induced along-stream ageostrophic front within the midtroposphere to the boundary layer through a thermally-indirect circulation. As the along-stream ageostrophic circulation intensifies within the middle troposphere down-stream from the mountain wave, sinking air parcels originating above 40 kPa descend to below 60 kPa over the High Plains where surface pressures are, only ∼85 kPa. These descending air parcels within the upstream branch of the along-stream ageostrophic thermally-indirect circulation contain high values of momentum and very low dewpoint values. As the planetary boundary layer (PBL) deepens due to surface warming during the morning hours, momentum and dry air from the midtropospheric along-stream ageostrophic front are entrained into the PBL. This process amplifies the bore-induced hydrostatic dryline bulge via low-level ageostrophic confluence. Finally, regions of low Richardson number (arising from strong vertical shears) within the amplifying midtropospheric along-stream ageostrophic thermally-indirect circulation become preferred regions for the development of non-hydrostatic evanescent internal gravity waves. These waves are embedded within the hydrostatic along-stream front above the low-level dryline and are accomapanied by very significant values of vertical momentum flux which act to focus the meso-gamma scale structure of the dryline into smaller scale bulges where low-level winds and vorticities are very high. This meso-gamma scale process follows the hydrostatic tilting and vortex tube stretching which creates meso-beta scale maxima of mid-lower tropospheric vorticity. The turbulent momentum fluxes accompanying wavebreaking within the nonhydrostatic dryline bulge create very large (i.e., stratospheric values of) potential vorticity near 70 kPa due to the nonconservation of potential vorticity on isentropic surfaces.

Notes: Summary A nonhydrostatic numerical simulation of a tropical cyclone is performed with explicit representation of cumulus on a meso-β scale grid and for a brief period on a meso-γ scale grid. Individual cumulus plumes are represented by a combination of explicit resolution and a 1.5 level closure predicting turbulent kinetic energy (TKE). The results demonstrate a number of expected and unexpected important scale interaction processes. Within the central core of the developing cyclone, meso-β convective regions grow and breakdown into propagating inertiagravity waves throughout the lifecycle of the cyclone. In the early stages, the amplitude of pressure fluctuations associated with the meso-β scale convection exceed the central pressure of the cyclone and strongly modulate its intensity. With each meso-β scale pulsation, the cyclone core increases in strength, measured by the central pressure deficit. The increasingly strong inertial frequency of the storm core acts to increasingly trap the convection induced heating within the core by balancing the tangential wind against the low central pressure, before the meso-β scale convection breaks down and sends the warmth away as a propagating wave. Eventually, the slow manifold's amplitude exceeds the amplitude of the meso-β scale oscillations and a stable eye region is formed. As inertial instability increases, increasingly high thermal warmth can be protected in the core, allowing persistent subsidence to form and to clear out the cyclone eye. On the outside of the eye wall, strong inertial stability gradients in the troposphere cause convective warming to split the inflow to the eye wal! and spawn outwardly propagating inertia gravity waves. These waves carry away all of the heating forced by convection that is not inertially trapped by the eye wall and act as a moderating influence on storm intensity. Inertia gravity waves are also spawned in the stratosphere at the top of the eye wall by the revolution of asymmetric cumulus structures. In all instances, the tropospheric waves are coupled to the propagating stratospheric waves which both move at 35 ms−1, although there are many instances where the stratospheric waves seem to have no tropospheric counterpart. Hence the anvil top forcing and low level breakdown are linked. The outwardly propagating inertia gravity waves act to initiate outer bands of convection. This initiation is with the assistance of low level boundary layer variations of density related to previous convection and to virga falling from the anvil which moistens and destabilizes the mid levels ofθ e minimum. The convection initiated by these waves does not move substantially outward with the wave, although may appear to develop outward discontinuously.

Notes: Summary The set of fully compressible nonhydrostatic equations governing a broad spectrum of atmospheric motion was transformed fromz coordinates to sigma coordinates under a hydrostatic base state. The hydrostatic base state may be either time-independent, such as a hydrostatic balance with-out motion or with motion such as a thermal wind balance, or time-dependent such as might be obtained from the result of integrating a hydrostatic model. The transformed set of equations can be used to predict and study all scales of at mospheric phenomena. The set of perturbation equations was also derived under the same condition. The computational sensitivity in computation of pressure gradient force in sigma coordinate can be improved by computing the pressure gradient interms of perturbations under a certain hydrostatic state. The hydrostatic regional spectral model developed by Juang and Kanamitsu (1991) was modified to be a nonhydrostatic spectral model based on the nonhydrostatic equations in sigma coordinates with time-dependent hydrostatic base states. A semi-implicit time integration scheme was used. Two experiments were performed to test this nonhydrostatic spectral model with acceptable results.

Notes: Summary Most finite-difference numerical weather prediction models employ vertical discretizations that are staggered, and are low-order (usually second-order) approximations for the important terms such as the derivation of the geopotential from the hydrostatic equation, and the calculation of the vertically integrated divergence. In a sigma-coordinate model the latter is used for computing both the surface pressure change and the vertical velocity. All of the above-mentioned variables can diminish the accuracy of the forecast if they are not calculated accurately, and can have an impact on related quantities such as precipitation. In this study various discretization schemes in the vertical are compared both in theory and in practice. Four different vertical grids are tested: one unstaggered and three staggered (including the widely-used “Lorenz” grid). The comparison is carried out by assessing the accuracy of the grids using vertical numerics that range from second-order up to sixth-order. The theoretical part of the study examines how faithfully each vertical grid reproduces the vertical modes of the governing equations linearized with a basic state atmosphere. The performance of the grids is evaluated for 2nd, 4th and 6th-order numerical schemes based on Lagrange polynomials, and for a 6th-ordercompact scheme. Our interpretation of the results of the theoretical study is as follows. The most important result is that the order of accuracy employed in the numerics seems to be more significant than the choice of vertical grid. There are differences between the grids at second-order, but these differences effectively vanish as the order of accuracy increases. The sixth-order schemes all produce very accurate results with the grids performing equally well, and with the compact scheme significantly outperforming the Lagrange scheme. A second major result is that for the number of levels typically used in current operational forecast models, second-order schemes (which are used almost universally) all appear to be relatively poor, for other than the lowest modes. The theoretical claims were confirmed in practice using a large number (100) of forecasts with the Australian Bureau of Meteorology Research Centre's operational model. By comparing “test” model forecasts using the four grids and the different orders of numerics with very high resolution “control” model forecasts, the results of the theoretical study seem to be corroborated.

Notes: Summary Convective to planetary scale processes govern the motion and structure of tropical storms. A model with a high resolution and a large domain is required for accurate prediction of a storm's track and intensity. A series of integrations are performed using a primitive equation model and an initial state that defines a tropical storm that later developed into a hurricane in the real atmosphere. Increasing the horizontal resolution or domain of the model improves the forecast track. However only the increase in the horizontal resolution produces a better hurricane structure. Banded structure in the vertical motion field, asymmetries in the low tropospheric winds similar to those observed and upper tropospheric cyclonic outflow develop in high horizontal resolution experiments. It is shown that horizontal advection and pressure gradient terms produce wind tendencies in the low troposphere that displace the vortex in the observed direction. A high pressure area surrounding the central low pressure area appears in the upper troposphere. Around this high pressure area large pressure gradients develop that induce outflow winds in the distal storm area.

Notes: Summary In this paper we present some recent work on typhoon prediction with a high resolution global model. The emphasis of this paper is on typhoon recurvature. Here we include examples of successful typhoon recurvature track forecasts made from a very high resolution global spectral model. The main objective of this study however is to go beyond the forecasts, i.e. to interrogate the history tapes and to diagnose residue-free budgets of the divergence and vorticity. The premise of this paper is that the recurvature of the typhoons depends on both the usual advection of vorticity by the layer mean winds and the advection of divergence in the outflow layers of the storm. The region immediately outside the heavy rain area of the storm experiences large values of divergent outflows which contribute a significant advection of divergence. Through the Dine's compensation this region must, in consort, experience an enhancement of low level convergence and of deep convection, thus contributing to the storm motion. We distinguish two facets of storm motion and recurvature, one based on the conventional steering that invokes the advection of vorticity by a vertical integrated flow, the other is the generation mechanism proposed here. During recurvature the storm appears to move in a direction which is influenced by the rotational and the divergent flow dynamics. Increased vertical resolution in the outflow layer is shown to resolve stronger amplitudes in the outflow layer divergence and thus to contribute to improved forecasts of recurvature. A number of processes seem to simultaneously evolve, these include the strong advection of divergence part of the wind, enhancement of cumulus convection over this region, an enhancement of lower tropospheric convergence, generation of vorticity of the lower troposphere and the attendant recurvature.

Notes: Summary A number of forecast experiments were performed in order to assess the capability of reproducing, by means of a limited-area numerical model, the highly structured mesoscale circulations occurring in the Po Valley of Northern Italy during a north-westerly cold front passage across the Alpine chain, with particular attention to the modelling of the effects of organized convection. The case-study occurred during summer 1987 and the model used throughout was the 1989 version of the UB/NMC Limited Area Model (University of Belgrade, National Meteorological Centre of Washington). The model was integrated both with eta, η, and sigma, ϑ, as vertical coordinates and ECMWF initialized analyses were always used as initial conditions. ECMWF initialized analysis or operational forecast fields were also used for updating in time the lateral boundary conditions. Experiments show qualitative and quantitative agreement with observations, both in upper-air geopotential height fields, in MSLP and in cumulated precipitation. Several modelling issues were also investigated, e.g. sensitivity of the results to horizontal and vertical model resolution and to the influence of the lateral boundaries poitioning, finding large effects of the latter on quantitative precipitation fields. Difficulties in modelling very localized mesoscale phenomena, e.g. organized convective thunderstorms in the Po Valley and Alpine North Foehn in the Milan area, were generally encounted.

Notes: Summary In this paper we present a methodology for evaluating rain rates from a mix of satellite and surface based observations. The component data sets include the outgoing longwave radiation (OLR), microwave radiometric data from the special sensor microwave imager (SSM/I) and surface raingauge data from the World Weather Watch. We have noted some deficiencies in the SSM/I algorithm-based rain rate over land areas; the OLR-based rain rates exhibit a larger lateral spread and lower intensities than the observed rainfall structures. The proposed combined method assimilates these three data sets to provide improved fields of global tropical rainfall.

Notes: Summary The Kuo-type cumulus parameterization and rainfall rate scheme is extended by including the outgoing longwave radiation (OLR), the local time rate of change of OLR, and the horizontal Laplacian of OLR to include the additional source of mesoscale moisture supply. The extended scheme remains simple and efficient. A series of 5-day forecasts of the 1979 monsoon for the tropical belt between the Arabian Sea and the western Pacific Ocean show improvement in the 3-day forecast in the daily accumulated precipitation in both the amount and location. Further RMS error analyses indicate that using OLR and the Laplacian of OLR also produces a significant improvement in a 3-day forecast. Additional tests of the extended scheme for the 1987 and 1988 monsoons produced consistent and characteristic areal rainfall rates in the tropics. The improvement in the “OLR model” forecasts is attributed to the improved skill of OLR forecast in the forecast model as the RMS errors for 5 consecutive days in the 6 experimental forecasts are smaller than those of the 3 control forecasts.

Notes: Summary A special analytical solution is derived for the classical orographic configuration of two-dimensional, stratified, linear, non-hydrostatic and dry model (without friction and Coriolis force). The well-known differential equation for the vertical velocity involves the vertical distribution of the Scorer parameterl 2(z) and in this casel 2 is specified such that the lower atmosphere has a stable duct near the surface and is capped by a layer which acts as a good reflector. Examination of the solution for the vertical amplitude in the vicinity of singularities indicates the dominant lee wavelength and observations confirm that in comparable settings resonant trapped gravity waves develop in the lee of mountains. Comparison with a real atmospheric lee-wave events gives good predictions for the wavelength and wave drag, but, as in other linear models, the amplitude is underestimated.

Notes: Summary In this paper we combine chaotic theory with statistics to present three forecast models: a model of equal distance ind-dimensional phase space, a mode regression model of twelve units and a model of neighborhood model regression. Many experiments show that all these models can generate accurate forcasts.

Notes: Summary Substituted poly(cyclohexene)s, used as poly(phenylene) precursors, have been prepared by radical polymerization of cyclohexadiene-1,2-diol derivatives containing various leaving groups. The precursors were converted into poly(phenylene) either by curing at elevated temperatures or by deep-UV exposure in the presence of a photoacid generator. These reactions were investigated by both IR and UV analysis. Our results with the conversion of precursors into poly(phenylene) via photoaromatization suggest that polyphenylene precursors can be imaged by deep-UV microlithography (as a new class of photoimageable thermally stable polymers).

Notes: Summary The cationic polymerization of various α- and β-substituted vinyl ethers, initiated by 1-iodo-1-(2-methylpropyloxy)ethane 1 and tetrabuty lammonium perchlorate (TBAP) was investigated. The polymerization of 2,3-dihydrofuran (DHF, 3a) in CH2Cl2 at -40°C proceeds via opening of the ethylenic double bond and yields polymers with narrow molar mass distributions and high glass transitions. The number average of molar mass increased linearly with conversion. Under these conditions, a controlled polymerization of two propenyl ethers (1-ethoxypropene 2a and 2-methoxypropene 2b) and two other cyclic unsaturated ethers (3,4-dihydro-2H-pyran 3b and 5-methyl-2,3-dihydrofuran 3c) could not be achieved. Either transfer reactions or the decomposition of 1 prevented the formation of high molar mass polymers of these vinyl ethers.

Notes: Summary 3-Vinylbenzothiophene was synthesized and its copolymerization with methyl methacrylate and n-butyl acrylate was investigated. The copolymerizations were performed according to an experimental design scheme and the results were analyzed using a nonlinear error-in-variables method. The 3-vinylbenzothiophene was found to be a reactive monomer with reactivity ratio values similar to those of 2-vinyl thiophene.

Notes: Summary Isotactic (it-) and syndiotactic (st-) MMA oligomers from 19-mer to 29-mer could be isolated efficiently from it-PMMA ( $$\overline {DP}$$ = 28.6) and st-PMMA ( $$\overline {DP}$$ = 28.6) (sample load: 50 mg) by the SFC using a 10 mm i. d. x 250 mm column packed with silica gel. DP of each isolated oligomer was determined by FD mass spectroscopy, and the values agreed well with those calculated from the relative intensity of 1H NMR signals due to CH3O- and the terminal t-C4H9-groups. Glass transition temperature (T g) of the it-28-mer measured by DSC was 34.5°C, which was higher than that of the it-PMMA by 6.5°C. T g of both the it-and st-oligomers increased linearly with DP in the range of DP=20∼29. A 1: 1 mixture of the it- and st-27-mers annealed at 140°C showed an endothermic transition at 102.3°C which was attributable to melting of stereocomplex, whereas an annealed 1: 1 mixture of the it- and st-PMMAs had a much broader endotherm around 80∼140°C.

Notes: Summary The coordination structures of Cu(II) complexes of amino functions supported on polyacrylamides with varying extents of NNMBA-crosslinks were followed by EPR techniques. The geometry of the Cu(II) complexes changes with increasing crosslinking. The covalency of the Cu-N bond also depends on the extent of the NNMBA-crosslinking in the polymer-support.

Notes: Summary The sorption behaviour of copper (II) and uranium (VI) ions on branched poly(ethylenimine) (BPEI) bridged with bifunctional crosslinkers (CR), 1-chloro-2,3-epoxypropane, 1,3-dibromopropane and 1,2-dibromoethane with various degress of crosslinks has been examined. The effect of crosslinking on the extent of sorption and thermal stability is reported.

Notes: Summary The mesophase formation was observed from the system of mixed organic polymer (hydroxypropyl cellulose) and inorganic polymer (imogolite) in acetic acid aqueous solution. The phase diagram of the mesophase formation was drawn as a function of imogolite content. The mesophase structure was found to change from the helicoidall arrangement of nematic sheets to the pile of pleated nematic sheets with increasing imogolite content.

Notes: Summary First unsaturated polyester fibers were prepared starting from stereoregular, macromolecular poly(octamethylene fumarate). Fibers obtained from octamethylene copolyesters of fumaric and terephthalic acids manifested improved mechanical properties and higher melting points. All unsaturated polyester fibers prepared in the study, based on the homopolymer and on copolymers of fumaric acid, even those containing as low as 10% of fumaric acid residues, are able to be covalently bonded to an unsaturated polyester matrix.

Notes: Summary Propylene oligomers containing isopropenyl end group have been prepared by thermolysis of atactic polypropylene. The chain-end structures and the number-avarage isopropenyl chain end functionality was determined in the product by C-13 NMR spectroscopy. Molecular weight of the oligomers were between 300 and 1000, as characterized by GPC. Conditions leading to the formation of propylene oligomers with number-average isopropenyl chain end functionality of 1.0, have been worked out.

Notes: Summary The photoaddition of aromatic dithiols (1) onto aliphatic alkenes (2a-2c) yielding polysulfides is studied. Polysulfides having anti-Markownikow and Markownikow moieties in the main chain are obtained by the reaction of dithiols (1) with ethyleneglycoldivinylether (2a). The unusual Markownikow orientation is explained on the basis of a radical cation intermediate.

Notes: Summary Radical polymerizations of vinyl monomers using a initiator of 2,2′-azobis(2-amidinopropane) dihydrochloride on monodispersed silica colloid led to formation of spherical polymer/SiO2 composites, retained particle size. Addition of hydroxypropyl cellulose to the reaction system resulted in yielding excellent dispersible composites into ethanol by short period ultrasonic irradiation. The polymerization of styrene in the presence of mercapto-amine or carboxylic acid derivatives could successfully introduce amino or carboxyl group on the Poly(styrene)/SiO2 composite.

Notes: Summary The interrelation between the electrical conductance, σ and some chemically modified cellulose molecule produced through partial substitution of the hydroxyl groups by different groups namely, acetate, methoxyl, carboxymethyl and sodium carboxymethyl has been studied in the temperature ranges 283–333 k. The results show that σ of the examined samples change in the descending order: sodium carboxymethyl cellulose 〉carboxymethyl cellulose 〉methyl cellulose〉cotton cellulose〉cellulose acetate. The variable response of σ to the chemical modification and the physical changes of cellulose accompanying such modification has been discussed in terms of the molecular structure, chain flexibility and degree of polymerization of the examined samples.

Notes: Summary Acidic parameters according to the GUTMANN's acceptor numbers (AN) of cellulose acetates and unmodified cellulose have been determined by means of the negatively solvatochromic probe dye Fe(phen)2(CN)2. Unmodified cellulose possesses a relatively high acceptor strength due to cooperative hydrogen bonds while increasing acetate contents in the polymer chain lower the acceptor strength. The dependence of AN on the acetate content can be used to estimate the degree of substitution (DS). Pecularities in the substitution interval (DS=0 to DS=1.5) are discussed.

Notes: Summary The complex forming poly[(ethylene glycol-co-proplene glycol)-g-acrylamide]: polyacrylic acid interpenetrating polymer network hydrogel is able to bend under electric field “stimuli”. pH, ionic strength gradients and voltage can influence it's bending degree. So we may improve the sample' “responsive” speed through manipulating those factor in the further study in order to put it into the biomedical application.

Notes: Summary An original way of reducing composition heterogeneity has been proposed for copolymers obtained at high conversions. The main idea underlying this method consists in application as initiators of special compounds (iniferters) leading to alteration of the mechanism of polymer chain growth.

Notes: Summary A reaction scheme based on propagation and intramolecular chain transfer steps is proposed for the anionic homopolymerization of epoxides initiated by tertiary amines. Chain transfer regenerates a living chain and gives a dead chain with terminal vinilydene unsaturations and hydroxy groups. The possibility of generating phenols or substituted phenols is also considered. Molecular-mass distributions were predicted as a function of conversion by both kinetic and Monte Carlo methods. Predictions were compared with experimental results reported in the literature. The evolution of the number-average degree of polymerization could be reasonably predicted.

Notes: Summary The coefficient of thermal expansion is measured for irradiated Polyvinyl Chloride (PVC) from 10K to 340K. The samples of PVC are irradiated, up to 500 Mrad in steps of 100 Mrad, in air at room temperature by using Co gamma rays with a dose rate of 0.3 Mrad/h. The PVC is an amorphous sample which is confirmed by X-ray diffraction. The coefficient of thermal expansion is found to decrease with radiation dose from 10K to 110K and it increaseswith radiation dose from 110K to 340K. The results are explained on the basis of radiation induced degradation of the sample.

Notes: Summary The synthesis of telechelic monodispersed diols produced from the radical telomerization of an excess of undecylenol with commercialy available α, ω-dithiols HSC2H4XC2H4SH (X=0, S or CH2) initiated by peroxides is presented. In each case, the diols were obtained selectively and quantitatively and they were characterized by both 1H and 13C NMR. Their physical characteristics (Tg, Tm and decomposition temperatures) were determined. Such compounds are thermally more stable than polydispersed telechelic commercially available diols.

Notes: Summary The anionic polymerization of dimethylphenylvinylsilane with sec-butyllithium/N,N,N′,N′-tetramethylethylenediamine (TMEDA) was investigated. The polymerization proceeded up to 100% yield and afforded the polymer having isomerized-structure units. The polymerization was accompanied by chain transfer reaction to the monomer and the polymerization rate in the presence of TMEDA was much lower than in the absence of TMEDA.

Notes: Summary Methacrylation of triglycidyl triphenyl methane (via methacrylic acid) has been done using three catalysts: dimethyl dodecyl amine (DMDA), tetrabutyl ammonium bromide (TBAB) and chromium (III) diisopropyl salicylate (Cr Dips). The reaction has been followed by epoxy colorimetric titration, CPG and 1H NMR. This study has shown the superiority of chromium catalysis because of its rapidity and ease of process. Then, these cured products (TACTIX and methacrylated TACTIX) show homogeneous Tg values which are higher than 200°C.

Notes: Summary Polyesters from 3,3′-bis(chloromethyl)oxacyclobutane and dipotassium isophthalate were obtained by phase transfer catalysis using different catalysts and solvents. The products were characterised by IR,1H-NMR and DSC.

Notes: Summary Polycarbonates, polythiocarbonates, and polyesters from 1,1,3-trimethyl-3-(4′-hydroxy-phenyl)-4-indanol were synthesized using phase transfer conditions. THe effects of several catalysts and reactions times were evaluated by the yields and inherent viscosities. Phase transfer catalysis was not an efficient technique due to the rigid structure of the diphenol with the indanic group. The results were compared with that obtained with a diphenol having the same number of carbon atoms but forming an aliphatic side chain.

Notes: Summary 1,2,3-Triphenylcyclopropene (TPCP) is a powerful retarder for polymerizations of methyl methacrylate (MMA) and styrene initiated by benzoyl peroxide or azobisisobutyronitrile. End-groups in polymers of MMA were studied by 13C-NMR spectroscopy and also, in the case of the peroxide, by using radioactive initiator. It was shown that, towards the benzoyloxy and 1-cyano-1-methylethyl radicals, the reactivity of TPCP exceeds that of MMA by factors of about 60 and three respectively at 60°C. TPCP can be used to introduce into polymers end-groups of special types.

Notes: Summary The influence of solvent on polyvinylpyrrolidone (PVP) and polyitaconic acid monomethylester (PMMI) sterecomplex formation was studied by means of laser light scattering and viscometry. Several phase changes were observed, from homogeneous solution to precipitates and gels. Responsible of this behaviour are hydrogen bonding, Coulombic forces, or hydrophobic interaction in aqueous medium.

Notes: Summary The Lewis and Mayo's rule, used so far for the determination of r1 and r2, is presently applied for the simultaneous determination of partial monomers conversions α1 and α2; whereas the integration of the Skeist's rule gave global conversion α only. An experimental verification is performed for the cotelomerization of MMA and maleic anhydride with dodecyl mercaptan as telogen, and it gives a very good correlation.

Notes: Abstract An anomalous effect on the twisted intramolecular charge transfer (TICT) phenomenon of 4-(N,N-dimethylamino) benzonitrile (DMABN) dissolved in elastomers such as poly(propylene oxide), poly(ethylene oxide) has been observed. Under irradiation, the normal fluorescence of DMABN in these matrices has been found to increase strongly while the emission arising from the TICT state decreases slightly.

Notes: Summary In this paper, the polymerisation of a conjugated liquid crystalline diacetylene is reported. The structure of the polymer is discussed in relation to results from spectroscopic studies and molecular weight determinations. The polymer has a backbone structure analogous to that of other polydiacetylenes.

Notes: Summary The preparation of a novel family of “liquid-crystalline” polyamide network gels is described. In these networks, the segments are stiff and longer than the critical axial ratio for mesomorphic behavior. The junctions are trifunctional and flexible. The gels are intensely birefringent in the relaxed nascent state, unlike fully rigid or fully flexible gels. The birefringence of the present gels is clearly associated with the coexistence in them of both long, stiff mesogenic segments and flexible trifurcated junctions. Thermal studies of the gels indicate very strong attractive interactions between the networks and the solvent.

Notes: Abstract Novel poly(acenaphtylene-b-isobutylene-b-acenaphtylene) (PAc-PIB-PAc) triblock copolymers exhibiting thermoplastic elastomer (TPE) properties have been prepared. The synthesis involved the addition of acenaphtylene (Ac) to living polyisobutylene dications (⊕PIB⊕) obtained by living isobutylene (IB) polymerization induced by the dicumyl methyl ether (DiCumOMe)/TiCl4 initiating system at-80°C. The triblocks contain very short polyacenaphtylene (PAc) blocks (Mn≈9,000) and consequently yield very soft, low modulus TPEs. Efforts to develop conditions for the living carbocationic polymerization (LC⊕Pzn) of Ac have failed.

Notes: Summary The cyanoethylation of cyclopentadiene was examined under a variety of reaction conditions. Approximately 9% of cyclopentadiene was converted to the desired hexa(β-cyanoethyl)cyclopentadiene when the amount of acrylonitrile to cyclopentadiene was increased from 2 to 7 equivalents under phase transfer conditions. The low conversion is due to competitive formation of various unreactive side-products. For example, termination leading to less-highly substituted products was confirmed by isolation of crystalline 1,1,2,3,4-penta(β-cyanoethyl)cyclopentadiene. Another side product isolated and characterized by 13C NMR was an oligomer of acrylonitrile attached to hexa(β-cyanoethyl)cyclopentadiene; the anion (at a β-alkyl position) of the latter apparently acted as anionic initiator. Attempts to induce thermal polymerization and cyclotrimerization of the pendent cyano groups of hexa(β-cyanoethyl)cyclopentadiene were unsuccessful even with added Lewis acid catalysts. Reduction to the hexaamine was only partially successful.

Notes: Summary Ternary catalyst systems for the polymerisation of 1,3-butadiene to high cis content were studied. The systems Nd(carboxylate)3/tert-butyl chloride/diisobutylaluminium hydride (carboxylate = naphthenate, versatate) were studied with respect to the order of catalyst component addition on catalyst activity and polymer characteristics. Stable catalysts which give relatively narrow molecular weight distribution are give by component addition order Nd(carboxylate)3+diisobutylaluminium hydride+tert-butyl chloride. Less stable systems giving broader polymer molecular weight distributions are given by addition orders tert-butyl chloride+diisobutylaluminium hydride+Nd(carboxylate)3 and Nd(carboxylate)3 +tert-butyl chloride+diisobutylaluminium hydride.

Notes: Summary The present study describes the preparation of polyorganosiloxanes containing dialkylaminopyridines in their side chains (POS-DAAPs) and the use of them as catalysts for esterolyses of p-nitrophenyl esters of CH3(CH2) n COOH (n=0–5). The POS-DAAPs (4, 5) were prepared from poly[(3-chlorocarbonylpropyl)methylsiloxane] (PCCPMS, 1) and two pyridine derivatives, such as 4-[(2-hydroxyethyl)methylamino]pyridine (HEMAP, 2) and 4-[4-(2-hydroxyethyl)piperidino]pyridine (HEPP, 3). Pyridyl groups of POS-DAAPs 4 and 5 were partially quaternized with dimethylsulfate (6, 7) in order to carry out esterolysis in homogenious systems. The esterolyses were examined in methanol/tris(hydroxymethyl)-aminomethane-hydrochloric acid buffer solution (vol. ratio 2/1, pH of buffer solution: 7.5) and analyzed following Michaelis-Menten like kinetics. The second-order rate constants (k 2/K m) of the esterolyses catalyzed by POSs 6 and 7 were 22–38 fold values of those catalyzed by the corresponding monomolecular catalysts 2 and 3. In addition, the effects of POSs were discussed from the kinetic, thermodynamic, and activation parameters.

Notes: Summary Copolymerizations of styrene and methyl methacrylate (MMA) have been carried out with azo-bis-(methyl isobutyrate-α-13C) (AIBMe-α-13C) as initiator and in the presence of ethyl aluminium sesquichloride (EASC). The specificity of the 1-methyl-1-(methoxycarbonyl)ethyl radical (I) for reaction with styrene over MMA is substantially enhanced by the presence of very low concentrations of EASC. This behaviour is consistent with the involvement of a complexes radical and suggests that such species may play an important role in Lewis acid induced alternating copolymerization.

Notes: Summary The model compound 1,4-bis(anisylimido)benzene has been characterized by solution and CP/MAS 13C NMR to assist in the characterization of liquid crystalline polyazomethines (PAM) based on the same mesogenic structure. Thermal behavior of several homologs of this PAM series have been compared before and after treatment with the end capping agent benzaldehyde. The results suggest that PAM oligomers containing large quantities of amine termination can strongly effect thermal behavior at constant oligomer molecular weight.

Notes: Summary A low temperature ESR technique has been developed for the observation of free radical intermediates generated in clear polymer films during photolysis by UV light under nitrogen. The technique is simple and reproducible, and can be used for polymers having glass transition temperatures at or about room temperature without the need to employ spin traps. The generation of free radicals can be monitored and quantified during exposure, and the radical yields obtained can then be correlated with the chemical structure of the polymer to provide a rapid predictive evaluation of the exterior durability of the polymer.

Notes: Summary Electrical conductivities and ESR spectra were obtained for polyaniline salts that contained different counter anions. The electrical properties were markedly different from one salt to another, although the concentrations of counteranions were almost identical. The ESR spectra showed that different types of unpaired electrons were created upon protonation. There was a close correlation between the charge-transport property and the nature of unpaired electrons created upon protonation.

Notes: Summary Multicomponent intermacromolecular complexes have been prepared from some typical phenolic copolymers with a non-ionic polymer (e.g. PVP), and a polyelectrolyte (e.g. PAA). Some transition metal ions (e.g. Cu(II) and Ni (II)) have been incorporated in the complex through its unreacted co-ordinating groups. The formation of these complexes has been studied by several techniques, such as viscometry, conductometry, potentiometry, IR and UV spectrophotometry. A scheme has been presented to explain the mode of interaction of the various components.

Notes: Summary The swelling and mechanical behaviour of networks of copolymers of acrylamide, methylenebisacrylamide and sodium 2-(2-carboxybenzoyloxy)ethylmethacrylate (mole fraction of salt x s =0–0.2) in water-acetone mixtures was investigated. In the range x s ≥0.01 phase transition (collapse) was observed, with both the extent of the collapse and the critical acetone concentration in the mixture at collapse, a c , increasing with increasing concentration of the salt. A comparison between these results and those obtained for networks with a quaternary ammonium salt led to a conclusion that an exchange of the positive charge of the ammonium salt (N⊕Cl⊖) for the negative charge of the sodium salt (COO⊖Na⊕) in the side chain decreases the critical content of salt necessary for the collapse, X s c , from 0.03 to 0.01, and the collapse takes place at lower concentrations of acetone. The collapse may also take place in a mixed solvent waterethanol; the dependence of network swelling on the concentration of ethanol is roughly the same as that on the concentration of acetone.

Notes: Summary Polysilanes containing cyclodisilazane units in the backbone were synthesized by the modified Wurtz-type coupling of available dichlorosilanes with N,N′-bis (chlorodimethylsilyl)tetramethylcyclodisilazane in the mixture of solvents. The effect of solvent additives on the polymerization process was examined. These polymers are soluble in common solvents and very easily handled by molding or casting.

Notes: Summary A triblock copolymer of isotactic(it)-poly(methyl methacrylate) (PMMA) and polyisobutylene (PIB), it-PMMA-block-PIB-block-it-PMMA, was prepared by anionic polymerization of triphenylmethyl methacrylate initiated with α, ω-dilithiated PIB diisobutyrate in tetrahydrofuran at -78°C, and subsequntt hydrolysis and methylation with diazomethane. Molecular weight distribution of the triblock copolymer was narrow, and the stereoregularity of the PMMA block was highly isotactic. Proton spin-lattice relaxation times of the block copolymer in acetone-d6, which is non-solvent for PIB but dissolves the block copolymer, indicate the aggregation of the copolymer through PIB block. Stereocomplex formation between the it-block copolymer and syndiotactic(st)-PMMA-block-PIB-block-st-PMMA was also studied.

Notes: Summary The synthesis and thermal degradability of poly (DL-lactide) were investigated. Key factors affecting the polymer molecular weight were found to be monomer recrystallization, initiator concentration and the vacuum level during drying/sealing of the polymerization reaction ampoule. It was found that poly (DL-lactide) is thermally unstable above its melting temperature. Monomer recrystallization, polymer precipitation and a low initiator content of the polymer significantly inhibited the rate and extent of thermal degradation.

Notes: Abstract The living carbocationic polymerization (LC⊕ Pzn) of p-methylstyrene (pMeSt) was achieved by the use of the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl4 initiating system in the presence of triethylamine (Et3N) electron donor in CH3Cl/nC6H14 mixed solvent at-80°C. Next, the synthesis, characterization, and some physical-mechanical characteristics of a series of poly (p-methylstyrene-b-isobutylene-b-p-methylstyrene) (PpMeSt-PIB-PpMeSt) triblocks is described. The latter synthesis involved two steps in one reactor: 1) The generation of diliving polyisobutylene dications (⊕PIB⊕) by the dicumyl chloride (DiCumCl)/TiCl4 system under similar conditions followed by 2) The addition of pMeSt and growth of living PpMeSt⊕ cations. The PpMeSt-PIB-PpMeSt triblocks are soft thermoplastic elastomers (TPEs).

Notes: Summary Polysquaraines and polycroconaines have been synthesized. They form a new class of polymers with a small band gap, down to 0.5 eV. The small gap arises from the regular alternation of strong donor and acceptor-like moieties in a conjugated backbone.

Notes: Summary Propylene oligomers with primary-OH, tertiary-0H andα,β-di-OH end groups have been prepared by converting the isopropenyl-ended oligomers with hydroboration-oxydation, oxymercuration-demercuration and performic acid hydroxylation reactions, respectively.

Notes: Summary Kinetics of polymerization has been studied in the system isobutylene/dicumylmethylether/BCl3 (CH2Cl2, −80°C) in the presence of dimethyl sulphoxide added as electron donor in a broad concentration range. The apparent propagation rate constant showed a DMSO concentration dependence typical for complex equilibria. At a given DMSO concentration, the apparent rate constant decreases with increasing initial monomer concentration showing a seemingly zero-order propagation. A possible explanation of this phenomenon is the formation of a chain-end/monomer complex. Equilibrium and propagation rate constants have been determined.

Notes: Summary In this technique, a relatively unreactive substance is transformed into a catalytically-active one within a protective environment. In this illustrative case, nickel formate was dissolved in a solution of poly(ethylene oxide) (PEO) in ethylene glycol, and then thermally decomposed in-situ to form finely-divided nickel particles. The mixture was dried, thereby protecting the nickel by encapsulating it in the polymer matrix. The distribution and the dispersity of nickel particles were investigated by electron microscopy. Upon adding portions of the catalyst-containing polymer to a reaction medium, the protective polymer dissolves, which releases the nickel particles and permits them to catalyze the reaction. In this particular case, the Ni-PEO sample was evaluated for the hydrogenation of an olefin, and found to be a highly efficient catalyst.

Notes: Summary The substitution patterns of methyl cellulose as well as of a thexyldimethylsilyl cellulose after permethylation were determined by hydrolysis and separation of the resulting partially methylated glucoses without further derivatization by h.p.l.c.. On an amine-modified silica column the solutes get separated into glucose, 2,3,6-tri-O-methyl glucose and the groups of mono-O-methyl-and di-O-methyl glucoses. A chromatographic run on a reversed-phase column enables the identification of the single mono-O-methyl- and di-O-methyl glucoses. In this way, a determination of both the average degree of substitution and the substitution pattern of cellulose derivatives is possible. Comparison of the results with those obtained by standard methylation analysis including g.l.c.-m.s. proves the correctnes of the method employed.

Notes: Summary The kinetics of the reaction between a styrene-maleic anhydride copolymer (SMA) and amines was investigated in tetrahydrofuran solution between 0°C and 40°C. This reaction converts the maleic anhydride (MA) into the corresponding amide-acid, while the consecutive reaction of the generated acid with amine forming a diamide or transformation of the acid-amide into the imide was not observed. The amine reactivity follows the order: 1-octylamine〉 〉1-methyl hexylamine〉 〉1,1-dimethyl propylamine or dibutylamine, demonstrating that the amine reactivity depends, to a large extent, upon its steric hindrance. This reaction is reversible as shown by IR at high temperatures, but the reverse reaction was undetectable between 0 and 40°C. The overall reaction involves spontaneous and autocatalytic reactions, and the overall reaction rate can be written as:-d[MA]/dt=k0[MA][-NH2]+k1[MA][-NH0]2. In the case of 1-octylamine below 0.02 M, the spontaneous reaction dominates (i.e, k0〉 〉k1[-NH2]).

Notes: Summary The chemiluminescence (CL) of polyethylene (PE) film induced by UV irradiation was investigated. CL parameter, I0, which indicates the oxidation rate under UV irradiation was obtained from a kinetic analysis. The I0 was found to be valuable to evaluate the durability of PE films.

Notes: Summary The effect of side chain length on intramolecular triplet energy migration of naphthalene containing polymers was investigated by a delayed fluorescence (DF) spectroscopy for the solid solution of the polymers. The degree of triplet energy migration depends strongly on whether the chromophores are directly attached to the main chain or not.

Notes: Summary The 300 MHz1H-nmr spectra of poly(5-bromo-2-vinylthiophene) and poly(4-bromo-2-vinylthiophene) are presented and analyzed in terms of polymer stereochemistry. In both cases, the spectra could be explained in terms of the polymers having a Bernoullian, atactic stereochemistry.

Notes: Summary The absolute rate constant of propagation (kp) in styrene polymerization was determined on the basis of ESR detection of the polymer radical in the temperature range of 0 to 130°C. The Arrhenius plot of kp gave a good linear relationship and the activation energy of the propagation was evaluated to be 39.7 KJ/mol. The termination rate constants over the same temperature range were also obtained by using the kp values according to the standard kinetics of radical polymerization. Apparent activation energy of the termination was estimated to be 15.6 KJ/mol.

Notes: Summary The elastic modulus of polyacrylamide-acrylic acid hydrogels is studied in a wide range of swelling degrees. The modulus does not follow the concentration dependence predicted by the rubber elasticity theory. At low swelling degrees this can be attributed to the constrained state (non-phantom behaviour) of the network chains. The reason for the increase of modulus at nigh swelling degrees is seen in the finite extensibility and topological entanglements of the chains. A theory including these effects is proposed and verified by experiment.

Notes: Summary Dehalogenation polycondensation of 1,4-diiodo-1,3-cyclohexadiene with zerovalent nickel complex gives a new π-conjugated polymer, poly(1,3-cyclohexadiene-1,4-diyl) PCyh. A copolymer constituted of 1,3-cyclohexadiene-1,4-diyl and 1,4-cyclohexadiene-1,4-diyl is also obtained by a similar method. The black color of PCyh indicates the presence of extensive π-conjugation along the polymer chain presumably due to takings-trans conformation of PCyh. PCyh is unstable and oxidized under air. IR and CP-MAS13C-NMR spectra of PCyh are reasonable for the structure.

Notes: Summary A fluorinated maleimide has been prepared from fluorinated diol with monofluoronitrobenzene. All the intermediates have been perfectly characterized by N.M.R. The study also describes the synthesis of a copolymer from a commercial vinyl ether and this maleimide. Copolymerization is not perfectly alternated as we could expect but the copolymer exhibits a glass transition equal to 165°C.

Notes: Summary Organoboron polymers were prepared by hydroboration polymerization between various dienes and thexylborane. These polymers were reacted with α-furyllithium followed by the treatment with acetic acid and then by the oxidative treatment to give the corresponding polyalcohols having primary and tertiary hydroxyl groups. The structures of the polyalcohols obtained were characterized by1H-NMR compared with that for model compound, which was prepared by the reaction of dioctylthexylborane with α-furyllithium. These conversions from organoboron polymers to polyalcohols include the migrations of two polymeric chains from boron atom to carbon and the ring-opening of furan ring.

Notes: Summary We describe the synthesis of monodisperse prepolymers containing one or two blocked isocyanate groups on the chain extremities. The prepolymers containing blocked isocyanate in one end and hydroxyl group in the other end are obtained by chemical transformation of undecylenic acid to acid chloride. This later was converted to the isocyanate by the CURTIUS reaction and blocked with nonyl-phenol. Finally the blocked isocyanate was telomerized with mercapto-ethanol. The resulting product is deblocked at T=105°C. By action of pure 2.4 T.D.I. (Tolylene diisocyanate) on the later product, we obtain a product containing blocked isocyanate end groups. The removal of the blocking agent could be effected at 100°C or less depending on the compound used to remove the blocking agent (amine).

Notes: Summary Cyclopolymerization was carried out by various catalyst systems. MoCl5-based catalyst systems are more effective for the polymerization of 4,4-diphenoxy-1,6-heptadiyne than WCl6-based catalyst systems. Polymerization of 4,4-diphenoxy-1,6-heptadiyne leads to soluble, purple colored polymer with number average molecular weight (Mn) of 3.6x104-5.2x104.1H- and13C-MNR, IR,and UV-visible spectra of the resulting polymer indicated that poly(4,4-diphenoxy-1,6-hepatadiyne) possesses a polyene structure presumably with cyclic recurring units in the polymer backbone. Poly(4,4-diphenoxy-1,6-heptadiyne) had good thermal and oxidative stability, and good solubility in organic solvents. The electrical conductivity of iodine-doped polymer was 10−3-10−2 S/cm.

Notes: Summary PET oligomers with different degrees of polymerization containing PHB as end groups were synthesized by melt condensation of bis(2-hydroxyethyl) terephthalate (BHET) in the presence of ethylp-hydroxybenzoate (EtPHB). Coupling the oligomers with terephthaloyl chloride, a series of block copolymers with identical triad aromatic ester “hard” segments as mesogen and different lengths of PET “soft” segments as spacer were obtained. Observation with a cross-polarized optical microscope shows that these copolymers are thermotropic in a certain range of the spacer length (n). Asn increases, the melting point (Tm) of the copolymer also increases, following the increasing molecular weight. The isotropic transition temperature (Ti) and the LC phase range (ΔT), on the other hand, decrease with the increasingn. Whenn exceeds a critical value, the LC phase disappears.

Notes: Summary A method is described for determining the absolute rate constants for the first few propagation steps in radical polymerization. The procedure involves a product analysis of the oligomeric alkoxyamines formed when an initiator is decomposed in monomer containing a very low concentration of a nitroxide radical scavenger. The method is illustrated with analysis of data for methyl acrylate. The rate constants for the first two propagation steps for polymerization of this monomer,k p(1) andk p(2), are at least an order of magnitude greater thank p(average). Values of the absolute rate constants for reactions of phenyl and primary alkyl radicals with methyl acrylate are also estimated.

Notes: Summary Ethylene and propylene co-polymerization and sequential polymerization with high activity supported titanium catalysts were studied. Specific rate of homopolymerization and copolymerization constants for ethylene and propylene were determined by using the derived values of the solubility constants for monomers in nascent polymers. The reason of the increased rate of co-polymerization upon enriching the monomers mixture with propylene, the effect of activation of ethylene polymerization upon preliminary polymerization of propylene may be in the increasing number of active sites due to enlarged content of amorphous phase in the nascent polymer product.

Notes: Abstract Correlations between positive pions are investigated in the target fragmentation region of 200A GeV16O+nucleus collisions. The pions are measured with the Plastic Ball detector in the WA80 experiment at the CERN SPS. The target mass dependence of the radii and the correlation strength extracted by interferometry is studied. A new approach to the fit of the correlation function is introduced. The correlation strength and both invariant and transverse radii increase with decreasing target mass. The transverse radius for16O+C reactions appears to be much larger than the geometrical radius of the nuclei involved. For the Au target only a small fraction of the measured pions contributes to the apparent correlation. Hints for a much larger second component in16O+Au reactions are observed. Rescattering phenomena may provide a clue to understand these phenomena.

Notes: Abstract We present results of a computer analysis of euclidean solutions of the SU(2) lattice gauge theory Hamiltonian for constant fields. The accumulation of tunneling solutions in a certain region of phase space is investigated because it is expected to give a strong contribution to the path integral. Our analysis shows, that an infinite set of classical trajectories with finite action exists, and describes how they cluster.

Notes: Abstract Corrected scaled-factorial-moments are calculated for the multiplicity distributions of shower particles in different phase spaces. An intermittency power-law is observed in the central collisions of32S and16O at 200A GeV,16O at 60A GeV and28Si at 14.5A GeV in nuclear emulsion.

Notes: Abstract We study scaling properties of the diffraction dissociation of virtual photons in a deep inelastic scattering. We concentrate on the total diffraction dissociation rate, diffraction excitation mass spectrum and the pomeron structure function to the lowest order in perturbative QCD. We calculate the valence structure function and the strangeness and charm content of the pomeron and estimate the ocean structure function using the pomeron factorization property. We find that quarks carry ≈ 10% of pomeron's momentum. Differential cross section of the (virtual) photon-pomeron scattering is found to exhibit features typical of the hadronic two-body reactions, supporting a treatment of the Pomeron as a particle, whereas the flavor dependence of structure functions does not support the particle treatment of the pomeron. Diffraction dissociation of photons is predicted to make ≈ 15% of the total deep inelastic scattering rate at smallx and largeQ 2. Detailed predictions for the mass spectrum and angular distribution of jets produced on the valence component of the pomeron are presented.

Notes: Abstract We use a recently developed numerical technique in order to evaluate the renormalized effective action of a spin 1/2 field with a chiral mass term, the chiral angle being given by a static hedgehog configuration. The method is based on the use of Euclidean Green's functions. The divergent parts are regularized and renormalized analytically. For the sum over all convergent contributions we obtain an exact expression that can be evaluated numerically. A precarious numerical subtraction of the divergent parts is avoided by making use of integral equations for the partial waves.

Notes: Abstract We report on the absolute luminosity measurement performed with the ALEPH detector at LEP. The systematic errors of the measurements in 1990 are estimated to be 0.6% (experimental) and 0.3% (theoretical).

Notes: Abstract The possible presence of hairpin diagrams is analyzed in th model-independent quark-diagram scheme for two-body decays of charmed mesons. Current experimental data do not require the presence of hairpin diagrams inD→VP (V: vector meson,P: pseudoscalar meson), in accordance with the OZI rule. However, there is a possible indication that they are important in the decay ofD→PP. The measurement ofD s + →π+η′ is crucial to test the mechanism of hairpin diagrams.

Notes: Abstract The quark cluster model has been previously shown to give a good description of the EMC effect and Drell-Yan dimuon pair production on nuclear targets at all values of the momentum fractionx. Here, we extend the quark cluster model in order to predictR G (x), the ratio of gluon structure functions in nuclei and nucleons. We find an increase in the average gluon momentum fraction as a function of the nucleon numberA, which agrees with recent results of the New Muon Collaboration (NMC) experiment.

Notes: Abstract A technique to sum up the regular corrections appearing under the analytical continuation from the space like momentum region to the time like one is proposed. A perturbative part of the inclusive semileptonic decay width of the τ-lepton in analyzed in detail.

Notes: Abstract The solutions of Lipatov-Fadin-Kuraev equation (LFK) within LLX approximation for gluon distributions are studied. The results are based on the semiphenomenological boundary conditions taken from LLQ2 analysis. We find, that pure theoretical LLX approach can reproduce the form of singular small-x behaviour of gluon and sea-quark distributions obtained within LLQ2A with singular input parametrizations. Some remarks about shadowing corrections are presented.

Notes: Abstract Transverse-momentum distributions of π andK have been analyzed within a framework of the hydrodynamical model to obtain the $$\sqrt s $$ dependence of the collective transverse flow and the dissociation temperatureT d inpp- and $$\bar pp$$ -induced multiparticle production reactions. The main outcomes are the steadily increasing transverse flow and a slowly decreasingT d as the incident energy increases. This behavior is in excellent agreement with early Landau's estimate. An extension of this to nucleus-nucleus collisions correctly gives account of the very soft component which has been observed in heavyion experiments.

Notes: Abstract We calculate the masses of the Higgs scalars and the lightest chargino for a large number of parameters of the supersymmetric standard model extended by a singlet. This allows us to estimate in which range we have to expect these masses naturally, and which region has to be covered experimentally in order to rule out a large fraction of the parameter space of low energy supersymmetry.

Notes: Abstract We present an analysis of multiplicity distributions of charged particles produced inZ 0 hadronic decays. The results are based on the analysis of 82941 events collected within 100 MeV of theZ 0 peak energy with the OPAL detector at LEP. The charged particle multiplicity distribution, corrected for initial-state radiation and for detector acceptance and resolution, was found to have a mean 〈n ch〉=21.40±0.02(stat.)±0.43(syst.) and a dispersionD=6.49±0.02(stat.)±0.20(syst.). The shape is well described by the Lognormal and Gamma distributions. A negative binomial parameterisation was found to describe the shape of the multiplicity distribution less well. A comparison with results obtained at lower energies confirms the validity of KNO(-G) scaling up to LEP energies. A separate analysis of events with low sphericity, typically associated with two-jet final states, shows the presence of features expected for models based on a stochastic production mechanism for particles. In all cases, the features observed in the data are well described by the Lund parton shower model JETSET.

Notes: Abstract The inclusive production of ρ0 mesons was measured in γp andh ± p collisions at beam energies of 65 GeV≦E γ≦175 GeV andE h =80, 140 GeV, respectively, whereh is π orK. Cross sections were determined for all beams and energies as functions ofx F (−0.1≦x F≦1.0),p T (0≦p T≦3.5 GeV/c) and the polar decay angle of the ρ0 by fitting the ρ0 signal in π+π- mass distributions. The ρ0 line shape is found to be distorted from a pure Breit-Wigner distribution throughout most of thex F−p T plane for both photon and hadron beams and a simple explanation is suggested. Throughout the paper emphasis is put on the comparison of photon and hadron beam data. The comparison of cross sections of γp andhp data provides a measure of the Vector Meson Dominance factor throughout thex F−p T range of the ρ0. The ρ0 production at lowp T can be described for both photon and hadron beams by a triple regge model at largex F. Similarly central production is well described by the quark-antiquark fusion model. At largep T there is an excess of ρ0 photoproduction which is consistent with the expected onset of pointlike photon interactions.

Notes: Abstract It is shown that in nucleus-nucleus collisions at 4.2 GeV/c per nucleon exists scaling of multiplicity of charged secondaries. The ratio of densities in the central region ρ n (y)/〈ρ(y)〉 is equal to the ratio of charged secondariesn/〈n〉. Deviation from this may be used for the description of collective effects (the quark-gluon plasma, etc.).

Notes: Abstract We consider an extension of the standard model with an extra neutral gauge bosonV which does not couple to the usual fermions or mix with the standardZ boson. A new fermion, which is either a color-triplet (Q) or a color-singlet (L), and a singlet Higgs scalar (X) are generic particles required for the extension group.V can be produced copiously by the process $$gg \to Q\bar QV$$ . We find 0760 0712 V 3 that there will be at least a few hundredV's produced at the SSC per year if the masses ofV andQ are less than 1 and 0.3 TeV respectively. Although the mixing of the standard and new Higgs scalars is small, the decay of the standard model Higgs scalar,H 1→2V, is comparable to the corresponding standard processes,H 1→2Z. A heavy standard model Higgs may open an important channel for the study of a new neutral gauge boson.