Optimal performance of an immersed membrane bioreactor equipped with a draft tube for domestic wastewater reclamation.

One of the options to prevent membrane fouling is to implement air lifting that can improve the cake removal from the membrane surface. This study presents the results of tests that were carried out at the Institutes for Desert Research, Kiryat Sde-Boker, Israel, and focused on the influence of hydrodynamic conditions on fouling in a pilot-scale immersed membrane bioreactor (IMBR) using a hollow fiber membrane module of ZW-10 (Zenon Environmental, Canada) under ambient conditions. In this system, the cross-flow velocities across the membrane surface were induced by one conical and four cylindrical draft-tubes. The relationship between the crossflow velocity and the aeration intensity, the influence of the crossflow on fouling rate under various hydrodynamic conditions were investigated and optimal operating conditions were obtained. Optimal operating conditions were reached during the long-term experiment period (70 days) for the treatment of domestic wastewater. The system was stable without external chemical cleaning. The results showed that the permeate was of high quality, and the removal of COD and BOD was 94.0% and 98.8%, respectively.The crossflow near the membrane surface reveals a major contribution for minimizing membrane fouling, and could offer guidelines for future design of similar systems.     

Determination of grain size in uranium-chromium alloys by ultrasonic attenuation

Ultrasonic attenuation was measured in cylindrical samples of uranium-chromium alloys used for nuclear fuel elements. The grain structure of the samples was previously refined by proper heat-treatment and the grain size in the range of 50 to 200 μm was determined by conventional metallographic methods. The attenuation coefficient,γ, was correlated with the mean grain diameter,ˉD, for three ultrasonic frequencies: 4, 6 and 12 MHz. The experimental results were compared with existing theories and good agreement was found with the curves based on Merkulov's analysis for cubic metals. A more practical result of this work was the development of a non-destructive testing procedure for grain-size determination in nuclear fuel elements cast from these alloys. The highest frequency (12 MHz) is normally used as it is more sensitive in the lower grain-size limit (50 to 100 μm) and only in border-line cases would one switch to the other frequencies (6 and 4 MHz) which are more applicable to the higher grain-size limit (100 to 200 μm).     

Membrane technology for advanced wastewater reclamation for sustainable agriculture production

Treated domestic secondary effluent is a valuable water source that can be reused for diverse purposes. However, in order to minimize health and environmental risks and to maintain adequate levels of sustainable agriculture production on a long range time scale, advanced treatment is required. Advanced effluent quality maintaining minimal risks can be primarily attained by implementing the membrane technology. Field experiments are in progress for secondary wastewater polishing for unrestricted reuse for sustainable agricultural production. The two stage membrane treatment system for the secondary effluent polishing consists of combining two main stages: ultrafiltration (UF) and reverse osmosis (RO) membrane treatment. The UF stage is efficient in the removal of the organic matter and the pathogens while the RO provides the dissolved solids (salinity) removal. Effluent of various qualities is applied for irrigation along with continuous monitoring of the membrane components performance. The experimental data was obtained in the ongoing pilot studies carried out near the City of Arad (Israel) wastewater treatment system (the pilot plant performs in a feed and bleed operation mode). The results indicate the importance of maintaining high quality effluent for sustainable agriculture production. The management modeling gives an idea of the importance in maintaining adequate UF flushing policy in order to minimize expenses due to fouling.     

The Vitality of Matter and the Instrumentalisation of Life

Artists and researchers Oron Catts and Ionat Zurr of SymbioticA, based at the School of Anatomy, Physiology and Human Biology at the University of Western Australia, are internationally renowned as pioneers in the field of biological arts, challenging audiences with their tissue engineering projects. Catts and Zurr discuss how synthetic biology has increasingly become ‘the new frontier for exploitation’ and why there is currently ‘a resurgence of the application of engineering logic in the fields of the life sciences’ in which life itself becomes a raw material.     

Tapered waveguide InGaAs/InGaAsP multiple-quantum-well lasers

The use of ultrathin etch-stop techniques to expand the vertical optical mode size adiabatically in 1.5-μm InGaAs/InGaAsP MQW lasers using a tapered-core passive intracavity waveguide structure is discussed. 30% differential quantum efficiency out the tapered facet, far-field FWHM of ~12° and a butt-coupling efficiency into a cleaved fiber of -4.2 dB, with -1-dB alignment tolerances of ~±3 μm, were achieved     

Y-junction power divider in InGaAsP-InP photonic integratedcircuits

A demonstration is presented of an InGaAsP-InP asymmetric waveguide Y junction with a power dividing ratio which is independent of the polarization of the input light. The Y junction is monolithically integrated with an active optical gain section by metalorganic chemical vapor deposition (MOCVD). The integrated chip represents a fundamental building block for photonic integrated circuits. Experimental results are in agreement with a theoretical analysis of the Y junction. The theory shows a low radiation loss (0.4 dB) and negligible power reflection (-63 dB) at the Y junction, which is ideal for monolithic integration with active devices. They also report on an integrated optical amplifier Y-junction-monitoring detector chip as an example of a photonic integrated circuit that employs the new Y-junction design. The estimated excess loss of the Y junction was 1.4 dB for the integrated chip, and the Y-junction reflectivity was found to be negligible     

Galpha14 and Galphaq mediate the response to trypsin in Xenopus oocytes

Xenopus oocytes respond to trypsin with a characteristic chloride current, virtually indistinguishable from responses mediated by a large number of native and expressed G protein-coupled receptors. We studied the involvement of G proteins of the Galphaq family as possible mediators of this and other G protein-coupled receptor-mediated responses in Xenopus oocytes. We have cloned the third member of the Galphaq family, Xenopus Galpha14, in addition to the previously cloned Xenopus Galphaq and Galpha11 (Shapira, H., Way, J., Lipinsky, D., Oron, Y., and Battey, J. F. (1994) FEBS Lett. 348, 89-92). Amphibian Galpha14 is 354 amino acids long and is 93% identical to its mammalian counterpart. Based on the Galpha14 cDNA sequence, we designed a specific antisense DNA oligonucleotide (antiGalpha14) that, together with antiGalphaq and antiGalpha11, was used in antisense depletion experiments. 24 h after injection into oocytes, either antiGalphaq or antiGalpha14 reduced the response to 1 microg/ml trypsin by 70%, whereas antiGalpha11 had no effect. A mixture of antiGalphaq and antiGalpha14 virtually abolished the response. These data strongly suggest that Galphaq and Galpha14 are the exclusive mediators of the trypsin-evoked response in Xenopus oocytes. Similar experiments with the expressed gastrin-releasing peptide receptor and muscarinic m1 receptor revealed the coupling of Galphaq and Galpha11, but not Galpha14, to these receptors in oocytes. These results confirm the hypothesis that endogenous members of the Galphaq family discriminate among different native receptors in vivo.     

Effect of cadmium on bone repair in young rats

The effect of cadmium (Cd) in drinking water on repair of bone at a site of hole injury to the tibia of young rats was followed using quantitative methods. The rats (3-4 wk old) were given 20 ppm and 200 ppm Cd for 5 wk and compared to a control group. A slight reduction (about 10%) in body weight and water and food consumption was observed in cadmium-exposed rats as compared to control rats. Clinical chemistry tests in the blood and histology of kidney, liver, and bone did not indicate changes related to Cd toxicity. A significant reduction (43%) in alkaline phosphatase (ALP) and tartarate-resistant acid phosphatase (TRAP) (46%) enzymatic activity was observed at 4 and 7 d postinjury respectively, in the site of injury in the rats receiving 200 ppm Cd in drinking water as compared to control rats. Calcium accumulation in the newly formed repair tissue at the site of injury was also significantly reduced (53%) at 13 d postinjury in the Cd-treated (200 ppm) rats as compared to control rats. It is concluded that Cd probably exhibits an effect on the bone repair process as reflected by reduction in ALP activity (osteoblastic cells) and mineralization at the site of injury in the tibia of young rats.     

Epitaxial 2D PbS Nanosheet-Formamidinium Lead Triiodide Heterostructure Enabling High-Performance Perovskite Solar Cells

Nanomaterials such as quantum dots and 2D materials have been widely used to improve the performance of perovskite solar cells due to their favorable optical properties, conductivity, and stability. Nevertheless, the interfacial crystal structures between perovskites and nanomaterials have always been ignored while large mismatches can result in a significant number of defects within solar cells. In this work, cubic PbS nanosheets with (200) preferred crystal planes are synthesized through anisotropy growth. Based on the similar crystal structure between cubic PbS (200) and cubic-phase formamidinium lead triiodide (α-FAPbI₃) (200), a nanoepitaxial PbS nanosheets-FAPbI₃ heterostructure with low defect density is observed. Attribute to the epitaxial growth, PbS nanosheets-FAPbI₃ hybrid polycrystalline films show decreased defects and better crystallization. Optimized perovskite solar cells perform both improved efficiency and stability, retaining 90% of initial photovoltaic conversion efficiency after being stored at 20 °C and 20% RH for 2500 h. Notably, the significantly improved stability is ascribed to the interfacial compression strain and chemical bonding between (200) planes of PbS nanosheets and α-FAPbI₃ (200). This study provides insight into high-performance perovskite solar cells achieved by manipulating nanomaterial surfaces.