Comparison of fouling propensity between reverse osmosis, forward osmosis, and membrane distillation

Resistance to fouling is often cited as an advantage of emerging desalination technologies such as forward osmosis and membrane distillation over the widely-used reverse osmosis process. However, the nature and magnitude of differences in fouling behavior between these three processes are not well characterized. This study directly compares the fouling and scaling behavior of reverse osmosis (RO), forward osmosis (FO), and direct contact membrane distillation (MD) in the same membrane module under identical hydrodynamic conditions (flux and cross-flow velocity). Fouling experiments were conducted using calcium sulfate as a model inorganic foulant and alginate as a model organic foulant. Although all three processes tolerated some degree of feed supersaturation for 36 h without inorganic fouling (scaling), FO exhibited the greatest scaling resistance, withstanding a feed of 33 ± 2 mM CaSO₄ (approximately twice saturation) without significant flux decline. Scaling occurred at similar concentrations at the membrane between MD and RO; however, while MD tolerated a more concentrated bulk feed due to reduced concentration polarization, flux decline after fouling was considerably more severe in MD. In contrast, MD tolerated organic fouling much better than FO or RO: despite accumulating a similar quantity of alginate gel over 18 h of operation, flux declined only 14% in MD versus 46–47% in RO and FO. These results are explained with respect to differences in temperature, membrane materials, and transport mechanisms between the three processes. Although FO and MD each exhibited superior resistance to one type of foulant, neither process outperformed RO in resistance to both organic and inorganic fouling. These findings inform a more nuanced approach to process selection for the treatment of complex water sources. Keywords: Desalination; Forward osmosis; Fouling resistance; Membrane distillation; Reverse osmosi

Mutant screen reveals the Piccolo's control over depression and brain-gonad crosstalk

Successful sexual reproduction involves a highly complex, genetically encoded interplay between animal physiology and behavior. Here we developed a screen to identify genes essential for rat reproduction based on an unbiased methodology involving mutagenesis via the Sleeping Beauty transposon. As expected, our screen identified genes where reproductive failure was connected to gametogenesis (Btrc, Pan3, Spaca6, Ube2k) and embryogenesis (Alk3, Exoc6b, Slc1a3, Tmx4, Zmynd8). In addition, our screen identified Atg13 (longevity) Dlg1 and Pclo (neuronal disorders), previously not associated with reproduction. Dominant Pclo traits caused epileptiform activity and affected genes supporting GABAergic synaptic transmission (Gabra6, Gabrg3), and animals exhibited a compromised crosstalk between the brain and gonads via disturbed GnRH signaling. Recessive Pclo traits disrupted conspecific recognition required for courtship/mating and were mapped to allelic markers for major depressive disorder (Grm5, Htr2a, Sorcs3, Negr1, Drd2). Thus, Pclo-deficiency in rats link neural networks controlling sexual motivation to Pclo variants that have been associated with human neurological disorders

Is alcohol beneficial or harmful for cardioprotection?

While the effects of chronic ethanol consumption on liver have been well studied and documented, its effect on the cardiovascular system is bimodal. Thus, moderate drinking in many population studies is related to lower prevalence of coronary artery disease (CAD). In contrast, heavy drinking correlates with higher prevalence of CAD. In several other studies of cardiovascular mortalities, abstainers and heavy drinkers are at higher risk than light or moderate drinkers. The composite of this disparate relation in several population studies of cardiovascular mortality has been a “U-” or “J-”shaped curve. Apart from its ability to eliminate cholesterol from the intima of the arteries by reverse cholesterol transport, another major mechanism by which HDL may have this cardioprotective property is by virtue of the ability of its component enzyme paraoxonase1 (PON1) to inhibit LDL oxidation and/or inactivate OxLDL. Therefore, PON1 plays a central role in the disposal of OxLDL and thus is antiatherogenic. Furthermore, PON1 is a multifunctional antioxidant enzyme that can also detoxify the homocysteine metabolite, homocysteine thiolactone (HTL), which can pathologically cause protein damage by homocysteinylation of the lysine residues, thereby leading to atherosclerosis. We demonstrated that moderate alcohol up regulates liver PON1 gene expression and serum activity, whereas heavy alcohol consumption had the opposite effects in both animal models and in humans. The increase in PON1 activity in light drinkers was not due to preferential distribution of high PON1 genotype in this group. It is well known that wine consumption in several countries shows a remarkable inverse correlation to local rates of CAD mortality. Significantly, apart from its alcohol content, red wine also has polyphenols such as quercetin and resveratrol that are also known to have cardioprotective effects. We have shown that quercetin also up regulates PON1 gene in rats and in human liver cells. The action of quercetin seems to be mediated via the active form of the nuclear lipogenic transcription factor, sterol-regulatory element-binding protein 2 (SREBP2) that is translocated from endoplasmic reticulum to the nucleus. However, the mechanism of action of ethanol-mediated up-regulation of PON1 gene remains to be elucidated. We conclude that both moderate ethanol and quercetin, the two major components of red wine, exhibit cardioprotective properties via the up-regulation of the antiatherogenic gene PON1