Sorption selectivity of NaY- and KY- zeolites for xylene and toluene

The selective adsorption capacities of NaY- and KY-zeolites for xylene isonners and toluene were investigated by measuring the rate of unidirectional diffusion in a batch adsorber and the breakthrough behavior in a fixed-bed column. The sequence of sorption selectivity was found as m-xylene> toluene > p-xylene with NaY-zeolites and as the converse with KY-zeolites. The reversal of selectivity could not be explained by the molecular sieving effects but by the interactions between adsorbing molecules and cation as well as among adsorbing molecules themselves.     

A quad 0.6-3.2 Gb/s/channel interference-free CMOS transceiver for backplane serial link

A quad-channel 0.6-3.2 Gb/s/channnel transceiver using eight independent phase-locked loops (PLLs) shows a 1-ps rms random jitter performance without interchannel interference. The PLL employs a folded starved inverter with high supply/substrate noise immunity and an analog coarse-tuning scheme for both seamless frequency acquisition and N-fold voltage-controlled-oscillator (VCO) gain reduction. A fixed-interval charge pumping is adopted for wide pumping-current range and large jitter tolerance. A wide-range delayed-locked loop (DLL) is utilized as a clock and reset generator for an elastic buffer. The transceiver, implemented in a 0.18-/spl mu/m CMOS technology, operates across a 30-in FR-4 backplane up to 3.2 Gb/s/ch with a bit-error rate of less than 10/sup -13/.     

An experimental study of critical heat flux in non-uniformly heated vertical annulus under low flow conditions

An experimental study on critical heat flux (CHF) has been performed in an internally heated vertical annulus with non-uniform heating. The CHF data for the chopped cosine heat flux have been compared with those for uniform heat flux obtained from the previous study of the authors, in order to investigate the effect of axial heat flux distribution on CHF. The local CHF with the parameters such as mass flux and critical quality shows an irregular behavior. However, thetotal critical power with mass flux and theaverage CHF with critical quality are represented by a unique curve without the irregularity. The effect of the heat flux distribution on CHF is large at low pressure conditions but becomes rapidly smaller as the pressure increases. The relationship between the critical quality and the boiling length is represented by a single curve, independent of the axial heat flux distribution. For non-uniform axial heat flux distribution, the prediction results from Doerffer et al.’s and Bowring’s CHF correlations have considerably large errors, compared to the prediction for uniform heat flux distribution. KeyWords : Critical Heat Flux, Heated Vertical Annulus, Low Mass Flux, Wide Range Pressure, Non-uniform Heating, Effect of Axial Heat Flux Distribution, Boiling Length     

AIDS in older people. A literature review for clinical nursing research and practice

Older Americans, 50 years of age and older, account for 10% of the 400,000 reported cases of AIDS nationwide (Centers for Disease Control and Prevention, 1994). the integrated literature review format in this article examines the published literature on HIV/AIDS in older adults. Most articles are case studies and reports, with only 17% having a research basis. The information reviewed indicates that older adults have different risk factors than younger populations for contracting HIV disease and a different pattern of disease progression. These differences create a need for knowledge of HIV infection and AIDS and its parameters in aging populations so nurses may provide both timely and appropriate care.