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Following the events of September 11, 2001, in the United States, world public awareness for possible terrorist attacks on water supply systems has increased dramatically. Among the different threats for a water distribution system, the most difficult to address is a deliberate chemical or biological contaminant injection, due to both the uncertainty of the type of injected contaminant and its consequences, and the uncertainty of the time and location of the injection. An online contaminant monitoring system is considered as a major opportunity to protect against the impacts of a deliberate contaminant intrusion. However, although optimization models and solution algorithms have been developed for locating sensors, little is known about how these design algorithms compare to the efforts of human designers, and thus, the advantages they propose for practical design of sensor networks. To explore these issues, the Battle of the Water Sensor Networks (BWSN) was undertaken as part of the 8th Annual Water Distribution Systems Analysis Symposium, Cincinnati, Ohio, August 27–29, 2006. This paper summarizes the outcome of the BWSN effort and suggests future directions for water sensor networks research and implementation. [ABSTRACT FROM AUTHOR]

• Novel rotational plate viscosity method was proposed for asphalt viscosity testing. • The method can be set up and performed using existing DSR machine. • The method provided reasonable construction temperatures for modified asphalt. • The method was more efficient, programmable, and accurate than traditional methods. The traditional method for determining mixing and compaction temperatures of asphalt binders, such as Brookfield viscosity test, often yields excessively high temperatures when used in many modified asphalts, and underestimates the temperature decreasing effect of the additives when used in warm-mixing asphalts. This study proposed a new viscosity measurement method, namely rotational plate viscosity (RPV) testing, to overcome these issues. The new method uses a Dynamic Shear Rheometer (DSR) with a 25-mm-diameter parallel plate geometry and a fixed shear rate 40 s−1 to measure the viscosity-temperature curve of modified asphalts, which minimizes the effect of the shear-thinning behavior. In addition, there are two main advantages of this new method. First, it can be carried out using an existing standard DSR machine typically used in most asphalt binder laboratories. Second, it can greatly improve the accuracy and efficiency of testing with sophisticated sensors and programmed settings. [ABSTRACT FROM AUTHOR]

• Investigation of performance degradation of three waste-oil-rejuvenated asphalts. • Underlying cause of performance degradation identified by SARA fractions analysis. • TLC-FID is introduced as an efficient SARA fractions analysis method for asphalt. In this study, the underlying causes of the performance degradation of three typical waste-oil-rejuvenated asphalts (i.e., asphalts rejuvenated by waste cooking oil (WCO), waste bio-oil (WBO), and waste engine oil (WEO)) after secondary aging are explored via SARA fractions analysis. The rejuvenation provided by WCO is found to be mainly based on supplementing aged asphalt with saturates, which causes the newly formed colloids to easily lose light components and exhibit low stability. Further, WEO contains some metal residues that catalyze the oxidation and polycondensation process of asphalt. Consequently, the performance of the asphalts rejuvenated separately by WCO and WEO is severely degraded during aging. By contrast, WBO has a stable colloidal structure and lacks ashes; thus, WBO-rejuvenated asphalt exhibits the most stable and reasonable performance degradation in the aging process. Our research suggests that the effect of rejuvenation on aged asphalt cannot be judged only by the difference between the performances of the rejuvenated asphalt and the original asphalt. The performance maintenance of the rejuvenated asphalt during the secondary aging process requires further investigation. [ABSTRACT FROM AUTHOR]

Hydrophobic membranes suffer from wetting and scaling when treating hypersaline brine using membrane distillation (MD). Thus omniphobic membranes with re-entrant surfaces have been developed by diverse modifications to enhance anti-wetting/scaling properties. However, those post-modifications usually sacrifice membrane permeability in spite of improved stability. In this work, omniphobic membranes were fabricated by decorating polyvinylidene fluoride (PVDF) nanofibrous membranes with different silica nanoparticles (SiNPs) followed by fluorination. Compared to unmodified nanofibrous and commercial PVDF membranes, both smaller SiNPs coated membrane #P-Min and larger SiNPs coated membrane #P-Max can perfectly sustain liquids with low surface tensions on their surfaces without wetting. In contrast to #P-Max with an oil contact angle of 136 ± 1°, #P-Min exhibited better oleophobicity with an oil contact angle of 152 ± 1°. In addition, the rigidity of their omniphobic properties was confirmed by testing in harsh conditions. Moreover, #P-Min successfully overcame the trade-off relation between membrane permeability and rejection with an enhanced MD flux due to more effective water evaporation area on membrane surface and a higher membrane porosity. While #P-Max was wetted by a hypersaline feed solution composed of 25 wt% NaCl, #P-Min could maintain a stable flux of 15 L m−2h−1 in a continuous 7-h MD operation, which proved its excellent performance for brine treatment. Furthermore, #P-Min exhibited less scaling tendency when feed was a saturated gypsum solution. Compared to #P-Max , the better anti-scaling properties of #P-Min should be due to its higher surface energy barrier, better slippery property and less solid-liquid contact area, which effectively impede crystal nucleation and attachment. Image 1 • Effects of nano-scaled roughness on membrane omniphobicity were studied. • As-prepared omniphobic membranes were stable under harsh conditions. • Omniphobic membrane coated with smaller NPs exhibited better performance. • It should be due to high surface energy barrier, slippery property and less solid-liquid contact area. [ABSTRACT FROM AUTHOR]

In this work, carbonyl-modified g-C 3 N 4 (CO-C 3 N 4) is prepared through one-step calcination of the melamine-oxalic acid aggregates. The visible light-assisted photocatalytic degradation efficiency of the tetracycline hydrochloride (TCH) for CO-C 3 N 4 is significantly enhanced by introducing the peroxymonosulfate (PMS), and the apparent rate constant is greatly increased from 0.01966 min−1 in CO-C 3 N 4 /vis system to 0.07688 min−1 in CO-C 3 N 4 /PMS/vis system. It is found that carbonyl for CO-C 3 N 4 might offer possible reactive sites for PMS activation and collection sites of photo-generated electrons, greatly accelerating carrier's separation for PMS activation. The favorable conditions, such as the higher catalyst dosage, higher PMS amount and alkaline pH, contribute to TCH degradation. The deleterious effects of co-existing anions on the TCH degradation efficiency are ranked in a decline: H 2 PO 4 − > SO 4 2− > HCO 3 − > NO 3 − > Cl−, and it may be affected by the type and amounts of anions and active radicals generated. The radical trapping tests and electron spin resonance (ESR) detection display that the O 2 −, h+, 1O 2 , OH and SO 4 − all contribute to TCH degradation. Meanwhile, possible degradation mechanism, intermediates and degradation pathway of TCH are revealed in CO-C 3 N 4 /PMS/vis system. This study will offer a new insight for constructing PMS activation with carbonyl modified g-C 3 N 4 photocatalysis system to achieve effective treatment of organic wastewater. Unlabelled Image • The carbonyl-modified g-C 3 N 4 is synthesized via one-step calcination. • The introduction of carbonyl accelerates carrier's separation and PMS activation. • The CO-C 3 N 4 possesses higher photocatalytic activity than g-C 3 N 4. • The performance of CO-C 3 N 4 is largely promoted with the addition of PMS. • O 2 −, h+ and 1O 2 mainly contribute to TCH degradation relative to •OH and SO 4 −. [ABSTRACT FROM AUTHOR]

Azobenzene (AB) units were successfully introduced into poly(1,6-heptadiyne)s in order to ensure smooth synthesis of double- and single-stranded poly(1,6-heptadiyne)s (P1 and P2) and simultaneously realize the self-assembly by Grubbs-III catalyst-mediated metathesis cyclopolymerization (CP) of AB-functionalized bis(1,6-heptadiyne) and 1,6-heptadiyne monomers (M1 and M2). Monomers and polymers were characterized by 1H NMR, mass spectroscopy, and GPC techniques. The double-stranded poly(1,6-heptadiyne)s exhibited a large scale of ordered ladder nanostructure. This result was attributed to the π−π attractions between end groups along the longitudinal axis of the polymers and van der Waals interactions between the neighboring polymeric backbones. While the Azo chromophore connected in the side chain of P2 induced conformation of micelles nanostructure during the CP process without any post-treatment. Furthermore, the photoisomerization of Azo units had an obviously different regulatory effect on the conjugated degree of the polymer backbone, especially for the single-stranded P2, which was attributed to the structural differences and the interaction between AB chromophores in the polymers. [ABSTRACT FROM AUTHOR]

Phased energy storage technologies are highly advantageous and feasible for storing and utilizing clean renewable energy resources, for instance, solar energy and waste heat, and it is an effective method to improve energy efficiency and save energy. However, phase change energy storage has some problems, for example, low thermal conductivity and phase change leakage, which lead to limited application. In this paper, anisotropic graphene aerogels were prepared by ice crystal template method with high thermal conductivity of graphene, and silver was attached to the pore wall graphene sheets and the graphene sheet boundaries of the aerogels. The results show that anisotropic graphene aerogels were successfully prepared, and SEM and EDS indicate that up to 9.14 at % silver was successfully attached to the graphene sheets and boundaries. The anisotropic thermal conductivity of the PArGO phase change composites after adsorption of the paraffin is significant, with a maximum axial thermal conductivity of PArGO of 1.20 W/(mK) and radial thermal conductivity of 0.54 W/(mK), compared to the pure paraffin (0.26 W/(mK)) increased by 362% and 108%, respectively. The enthalpy of the composite has been reduced to 149.6 J/g due to the silver particles attached, but the thermal properties have been greatly improved. In experiments simulating real temperature changes, PArGO achieves phase transitions very fast, with a 74% improvement on thermal efficiency of storage and discharge over the pure paraffin. [ABSTRACT FROM AUTHOR]

• The microbial community in wastewater play an important role in current generation. • The presence of aerobic bacteria in the sample reduces the current generation. • The anode needs to be cultured by the same source of water a prior measurement. • Pretreatment of bacteria before testing may improve the accuracy and reliability. • Two ways to reduce the systemic error in testing wastewater were firstly proposed. Microbial fuel cells (MFCs) based sensors had been studied in measuring biochemical oxygen demand (BOD) or the equivalent chemical oxygen demand (COD) recently. Limited attention has been paid to the effect of the microbial communities in wastewater on the responses of these sensors. This study systematically evaluated, for the first time, the effect of wastewater samples from a variety of sources on the electrical response of a micro-fabricated double-chamber MFC device. It was found that the response of the MFC is positively correlated with the bacterial composition, in particular electroactive bacteria. The presence of aerobic bacteria in the sample reduces the current generation. These findings indicated that the bacterial content of the water sample could be a significant interference source and must be considered in the use of µMFC-based sensors. Filtering samples may be effective in improving the reliability of these microsensors. [ABSTRACT FROM AUTHOR]