Phase behaviour and separation kinetics of polymer blends.

The liquid-liquid phase separation kinetics and phase behaviour of hydrogenated polyethylene and deuterated polypropylene blends have been systematically studied by optical microscope. Phase diagram was constructed from the phase transition temperature. The hydrogenated polyethylene/deuterated polypropylene blend exhibits upper critical solution temperature in the melt. The time evolution of the characteristics morphology for liquid-liquid phase separation is determined for the hydrogenated polyethylene/deuterated polypropylene blend at various compositions and following a quench from initial homogenous melts at higher temperature to various lower temperatures. Liquid-liquid phase separation kinetics follows nucleation and growth mechanism. The experimental results from optical microscope measurement at various conditions are all consistent with the nucleation and growth mechanism.

Photoionization of CH(3)I mediated by the C state in the visible and ultraviolet regions.

Three/two-photon resonant multiphoton ionization (MPI) of the CH3I monomer has been studied in the gas phase at 532 and 355 nm using time-of-flight mass spectrometry. Under low laser intensity (approximately 10(9) W/cm2) the mass spectra showed peaks at m/z 15, 127 and 142, corresponding to [CH3]+, [I]+ and [CH3I]+ species, at both these wavelengths. The laser power dependence for [CH3I]+, [I]+ and [CH3]+ ions showed a three-photon dependence at 532 nm. For the same three ions, photoionization studies at 355 nm gave a power dependence of 2. Both these results suggest that a vibronic energy level at approximately 7 eV, lying in the Rydberg C state, acts as a resonant intermediate level in ionization of CH3I. In the case of 355 nm, with increasing intensity additional peaks at m/z 139 and 141 were observed which could be assigned to [CI]+ and [CH2I]+ fragments. In contrast, for high intensity radiation at 532 nm ( approximately 2 x 10(10) W/cm2), only the [CI]+ fragment was observed. At these wavelengths, fragment ions observed in mass spectra mainly arise from photodissociation of the parent ion. Experiments at another wavelength in the visible region (564.2 nm) confirmed the results obtained at 532 nm. In order to assess the role of the A state in these MPI experiments, additional experiments were performed at 266 and 282.1 nm, which access the A state directly via a one-photon transition, and showed absence of a surviving precursor ion. Reaction energies for various possible dissociation channels of CH3I/[CH3I]+/[CH2I]+ were calculated theoretically at the MP2 level using the GAMESS electronic structure program.

Characterization of a multilayer highly reflecting mirror by spectroscopic phase-modulated ellipsometry.

The characterization of optical multilayer coatings has been a challenging task for thin-film scientists and engineers because of the various complex, interdependent layer parameters that exist in the system. Spectroscopic phase-modulated ellipsometry has some advantages in the postanalysis of the layer parameters of such multilayer coatings because it suitably models the layer structure with respect to the ellipsometric measurements. An algorithm to characterize multilayer optical coatings with large numbers of layers has been described by spectroscopic ellipsometry by use of a discrete spectral zone fitting approach. A 23-layer multilayer highly reflecting mirror has been characterized by this technique in the wavelength range 280-1000 nm. The ellipsometric spectra (? and D versus wavelength) have been fitted separately in three wavelength regimes. Fitting the ellipsometric spectra in the wavelength regime of 700-1000 nm permitted the sample structure to be determined. The data were then fitted in the wavelength range 280-340 nm, i.e., near the fundamental absorption edge of TiO(2), to yield the dispersion relation for the optical constants of TiO(2). Finally, the data were fitted in the wavelength range 340-700 nm, and the true dispersion of the refractive index of TiO(2), along with the best-fitting sample structure, was obtained.

Image Evaluation of the High Resolution VUV Spectrometer at SURF II by Ray Tracing.

A high resolution VUV spectroscopic facility has been in use for several years at SURF II, the Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology in Gaithersburg, Maryland. At this facility, a combination of three cylindrical mirrors is utilized to focus the light originating in the storage ring onto the horizontal entrance slit of the spectrometer. The spectrometer uses a 6.65 m concave grating having a groove density of 4800 lines/mm in the off-plane Eagle mounting. In preparation for the installation of an array detector in the exit image plane, a ray tracing program has been formulated and spot diagrams have been constructed by plotting the coordinates of the points of intersection of the diffracted rays with the image plane, which is tangent to the Rowland circle. In creating the spot diagrams, we have considered both parallel and tilted configurations of the entrance slit with respect to the grating grooves. It is shown that the line widths of the spectral images can be reduced when the entrance slit is properly tilted. Finally, we have estimated the spectral widths of the images when they are recorded on an array detector placed tangent to the Rowland circle. We conclude that an image spectral width of 0.41 pm to 0.88 pm in first order can be achieved over the wavelength region of 40 nm to 120 nm.

A design of a vermiculite column adsorber for the removal of lead from water.

Mini-column techniques were employed to determine the mass transfer coefficient for lead adsorption onto vermiculite. Variation of the mass transfer coefficient with flow rate, particle size of sorbent, and influent lead concentration were studied. Multiple linear regression (MLR) analysis showed that the mass transfer coefficient varied as the 0.43 power of the liquid flow rate and inversely as the 0.272 power of particle diameter of the vermiculite, but was independent of the influent concentration of lead. Different parameters of a fixed bed column design for the removal of lead by vermiculite were determined using the data from the batch sorption study. The performance of the liquid bed column in removing lead was in close agreement with predicted performance using the batch isotherm data.

Vital rates of India for intercensal period with declining fertility and declining mortality.

PIP: This paper presents estimation of vital rates of the population of the 1981 census in quasi-stable state by adjusting estimates based on the stable population model for effects of declining fertility as suggested in the U.N. Manual IV. The decadal growth rate of population and the age distribution from the 1921 census through the 1971 census makes it evident that mortality has been improving since 1921 while fertility remained constant over the 1921-71 period in India. the decadal growth rate of the population and the age distribution for the 1981 census indicate that the destabilization of the population during the 1971-81 intercensal period was brought out by declining fertility and declining mortality. The rise in the proportion of population aged 60 years and above from 4.1% in the 1931 census to 6.49% in the 1981 census indicates a steady improvement in mortality during the period of 1931-1981. The Sample Registration System (SRS) was launched in India in the mid-1960s to furnish plausible estimates of annual rates of vital events. The SRS estimate of birth rate for 1980-82 was 35.4 for the rural population, 27.6 for the urban population, and 33.6 for the whole population, as opposed to the quasi-stable estimates of 37.5, 30.8, and 36, respectively. Thus, the birth rate for 1980-82 was underestimated in the SRS by a margin of 6%, 10%, and 7% for the respective populations. The SRS estimate of death events for 1980-82 was 13.5 for the rural population and 7.7 for the urban population. By weighing proportions of rural and urban population to total population in the 1981 census, the death rate for the whole population for 1980-82 was estimated at 12.2 as opposed to the quasi-stable estimate of 14.5. Thus, the death rate was underestimated in the SRS by a margin of 16%. In sum, the rate for quasi-stable state for 1981 was estimated at 36 for birth events, representing a 7% underestimation by SRS and at 14.5 for death events, representing a 16% underestimation by SRS.^ieng

Theoretical evaluation of the high-resolution vacuum ultraviolet spectrometer on SURF II.

The high-resolution vacuum-ultraviolet spectroscopic facility at SURF II, the Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology in Gaithersburg, Md., consists of a fore-optics system of three cylindrical mirrors and a 6.65-m concave grating spectrometer using the off-plane Eagle mounting. To prepare for the evaluation of the actual performance of this nationalfacility spectrometer against theoretical expectations, we computed scanning parameters, spectral resolution, and the optimum curvature and tilt of both entrance and exit slits. It is planned eventually to replace the exit slit of this instrument with a two-dimensional array detector to increase data collection efficiency. Therefore a major motivation for this work is that the results on the tilt and curvature of the exit slit can be used to maximize the resolution obtainable with the array detector through data processing.

Aberration properties of a Czerny-Turner spectrograph using plane-holographic diffraction grating.

In this paper I discuss the construction and the aberration properties of plane-holographic diffraction gratings in a Czerny-Turner mounting. A ray-tracing scheme has been formulated for computing the aberrations of the system. It has been found that in the area near the recording wavelength for the holographic grating, the system has better resolution than does a conventional grating system. The design parameters of a medium-sized holographic grating spectrograph are specified. The performance of the spectrograph is evaluated by plotting spot diagrams, which show that astigmatic defects are much reduced.

A note on the estimation of marriage rate from census data.

"The level and trend in nuptiality for the developing countries can not be studied because necessary data are not available. A broad idea of the trend is obtained by examining the never-married proportion for different age cohorts at different censuses. In this paper, a methodology for estimating age-specific marriage rates from census data is presented." (SUMMARY IN FRE AND ITA)

Cohort fertility by age at marriage and marriage duration.

PIP: The data presented here on cohort fertility by age at marriage and marriage duration were collected in the 19th round (July 1964-July 1965) of India's National Sample Survey. The data on fertility history collected in rounds 17 through 19 were tabulated by age at effective marriage. The couples were classified by wife's age at effective marriage below 15 years, 15-19 years, and 20-24 years. If age at effective marriage was recorded at an age lower than 12 years, age at effective marriage was treated as 12 years. From data of the 19th round, cohorts of married women were tabulated by parity and age at effective marriage. The said distributions refer to those by parity and wife's age at effective marriage for different marriage duration groups. The study is based on the assumption of natural fertility over age range between age at effective marriage and that at marriage duration of 15-19 years for women married at age below 20 years and between age at effective marriage and that at marriage duration of 10-14 years for women married at ages 20-24 years. The estimate of proportion having no child birth within a period of 15-19 years after effective marriage came out to be close to that of the corresponding proportion at marriage duration of 30 years and older for urban women married at ages below 20 years. In case of urban women married at ages 20-24 years, estimates of proportion having no child birth within a 10-14 year period after effective marriage and that of the corresponding proportion at marriage duration of 20-29 years are not close estimates as in cases of women married at ages below 20 years. Yet, the estimate came out to be almost of the same order of magnitude. For rural women married at ages 15-19 years, estimate of proportion having no child birth at marriage duration of 30 years and above came out to be nearly 20% higher than that of the corresponding proportion at marriage duration of 15-19 years. The estimate of proportion having no child birth at marriage duration of 30 years and above came out to be nearly 70% higher than that of the corresponding proportion at marriage duration of 15-19 years for rural women married at ages younger than 15. The women married at ages 20-24 years and remaining without child birth within a period of 10-14 years after effective marriage and those married at ages below 20 years and remaining without child birth within a period of 15-19 years after effective marriage may be treated as sterile. The proportion having realtive parity 5 and above among women married at ages 20-24 years came out at 36%: the corresponding proportion among women married at ages below 20 years came out as 46%.^ieng