REMOVED: Reverse Solute Diffusion and its Adverse Effect on Osmotic Power Production in Pressure Retarded Osmosis

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A critical force constant of the structural phase transition in quartz

Long wavelength optical phonons of quartz were analyzed by a Born-Von Karman model not previously used. It was found that only one force constant associated with the turning of the Si-O bonds has a critical effect on the soft-mode frequency and the α-β transition in quartz. The square of the soft-mode frequency was found to depend linearly on this force constant which has the temperature dependence K(T)= -5.33+225.3x10-4(851-T)2/3 in units of 104 dyn/cm2

Universally valid reformulation of the Heisenberg uncertainty principle on noise and disturbance in measurement

The Heisenberg uncertainty principle states that the product of the noise in a position measurement and the momentum disturbance caused by that measurement should be no less than the limit set by Planck's constant, hbar/2, as demonstrated by Heisenberg's thought experiment using a gamma-ray microscope. Here I show that this common assumption is false: a universally valid trade-off relation between the noise and the disturbance has an additional correlation term, which is redundant when the intervention brought by the measurement is independent of the measured object, but which allows the noise-disturbance product much below Planck's constant when the intervention is dependent. A model of measuring interaction with dependent intervention shows that Heisenberg's lower bound for the noise-disturbance product is violated even by a nearly nondisturbing, precise position measuring instrument. An experimental implementation is also proposed to realize the above model in the context of optical quadrature measurement with currently available linear optical devices.Comment: Revtex, 6 page

Complementarity and the uncertainty relations

We formulate a general complementarity relation starting from any Hermitian operator with discrete non-degenerate eigenvalues. We then elucidate the relationship between quantum complementarity and the Heisenberg-Robertson's uncertainty relation. We show that they are intimately connected. Finally we exemplify the general theory with some specific suggested experiments.Comment: 9 pages, 4 figures, REVTeX, uses epsf.sty and multicol.st

Evidence of a gravity wave breaking event and the estimation of wave characteristics from sodium lidar observations over Fort Collins CO (41°N

Geophys. Res. Lett., 34, LO5815The article of record as published may be located at http://dx.doi.org/10.1029/2006GL02898

Osmotic power production from salinity gradient resource by pressure retarded osmosis: effects of operating conditions and reverse solute diffusion

Pressure retarded osmosis (PRO) is a potential technology to harvest the renewable osmotic power from the salinity-gradient resources. This study systematically investigated the effects of operating conditions (feed and draw solution concentration, membrane type, membrane orientation, and temperature) and reverse solute diffusion on PRO performance using commercially available osmotic membranes. The PRO performance was improved by decreasing the feed solution concentration, increasing the draw solution concentration, orientating the membrane with active layer facing draw solution (AL-DS), and increasing temperature. The membrane with higher water permeability, lower solute permeability and lower structure parameter performed better in PRO process. However, the experimentally obtained power densities for all the membranes used in this study were lower than the predictions from conventional ICP model that assumes membrane separation parameters are constant in PRO process. It was found that this was mainly caused by the severe reverse solute diffusion and thus the enhanced internal concentration polarization (ICP) in PRO. The specific reverse solute flux was found to increase with increasing the applied hydraulic pressure, but the increase of experimental results was much more drastic than the theoretic prediction especially under higher hydraulic pressure, probably due to the increased solute permeability caused by membrane deformation

Removal of boron and arsenic by forward osmosis membrane: influence of membrane orientation and organic fouling

The potential application of forward osmosis (FO) membranes in water treatment and desalination requires an improved understanding of the factors that govern the rejection of trace contaminants. This study investigated the influence of membrane orientation and organic fouling on the performance of FO membrane in removing boron and arsenic. Results of laboratory-scale crossflow membrane filtration experiments showed that the inorganic contaminants were rejected at a much lower rate when membrane active layer was facing draw solution (AL-DS) compared to the active layer-facing feed water (AL-FW) orientation, as a result of the more severe concentrative internal concentration polarization (ICP) in the latter orientation. The difference in boron rejection between the two membrane orientations was greater due to its higher permeability through the FO membrane. In the AL-FW orientation, the formation of an alginate fouling layer on the membrane surface could enhance the sieving effect and thus improve the rejection of arsenious acid with relatively larger molecular size. In the AL-DS orientation, alginate fouling in the membrane support layer had adverse effect on boron rejection at water flux below 4.2 μm/s (15.3 L/m<sup>2</sup>/h), attributed to the foulant enhanced concentrative ICP effect. Findings have important implications in the performance and applicability of FO membrane processes

Relating reverse and forward solute diffusion to membrane fouling in osmotically driven membrane processes

Osmotically driven membrane processes, such as forward osmosis (FO) and pressure retarded osmosis (PRO), are attracting increasing interest in research and applications in environment and energy related fields. In this study, we systematically investigated the alginate fouling on an osmotic membrane during FO operation using four types of draw solutions (NaCl, MgCl<sub>2</sub>, CaCl<sub>2</sub> and Ca(NO<sub>3</sub>)<sub>2</sub>) to elucidate the relationships between reverse (from draw solution to feed solution) and forward (from feed solution to draw solution) solute diffusion, and membrane fouling. At the same water flux level (achieved by adjusting the draw solution concentration), the greatest reverse solute diffusion rate was observed for NaCl draw solution, followed by Ca(NO<sub>3</sub>)<sub>2</sub> draw solution, and then CaCl<sub>2</sub> draw solution and MgCl<sub>2</sub> draw solution, the order of which was consistent with that of their solute permeability coefficients. Moreover, the reverse solute diffusion of draw solute (especially divalent cation) can change the feed solution chemistry and thus enhance membrane fouling by alginate, the extent of which is related to the rate of the reverse draw solute diffusion and its ability to interact with the foulant. The extent of fouling for the four types of draw solution followed an order of Ca(NO<sub>3</sub>)<sub>2</sub> > CaCl<sub>2</sub> >> MgCl<sub>2</sub> > NaCl. On the other hand, the rate of forward diffusion of feed solute (e.g., Na+) was in turn promoted under severe membrane fouling in active layer facing draw solution orientation, which may be attributed to the fouling enhanced concentration polarization (pore clogging enhanced ICP and cake enhanced concentration polarization). The enhanced concentration polarization can lead to additional water flux reduction and is an important mechanism governing the water flux behavior during FO membrane fouling. Findings have significant implications for the draw solution selection and membrane fouling control in osmotically driven membrane processes