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Gravitational waves from precessing binary black holes exhibit new features that are absent in non-precessionary systems. All current waveform models take into account only the modulation of the signal due to precession. In this letter, we find that this effect has its own signature, by gravitational emission of a short and transient signal, or burst. The frequency of the burst is comparable to that of the late stage of the inspiral. We show that under certain conditions, this signal is strong enough to be detected by Advanced LIGO. For third-generation detectors like the Einstein telescope, the calculated signal-to-noise ratio can reach higher values. Measurements of precession would provide valuable insights into the intrinsic structure of black holes, and therefore into astrophysical binary formation mechanisms., Comment: 5 pages, 2 figures

The cross-laminated timber and glulam structural members could be used as structural members for mid- and high-rise buildings. Reliability of wood buildings designed following Canadian practice and...

This work aimed to improve sludge disintegration and nutrient solubility using synergism of a surfactant (sodium dodecylbenzene sulfonate (SDBS)) and ultrasound. The results illustrated that the critical micelle concentration (CMC) of the surfactant (0.025 g SDBS/g total solid (TS)) was significantly related to the cost-effective pre-treatment performance. The particle sizes of Dx(10) and Dx(50) were decreased from 16.4 μm and 55.4 μm to 3.69 μm and 12.9 μm, respectively, under a 600 W ultrasound input with the CMC of SDBS. As the surfactant dosage was further increased (0.05 SDBS g/g TS), the maximum increment rates of total nitrogen (TN) and total phosphorus were obtained at 1250.1% and 197.1%, respectively. However, higher pre-treatment efficiency could be achieved when SDBS was below the CMC. It related to the decrease of surface tension. Based on the economic evaluation, the total cost significantly increased when the amount of surfactant was greater than the CMC.

Rapid single flux quantum (RSFQ) circuits are a kind of superconducting digital circuits, having properties of a natural gate-level pipelining synchronous sequential circuit, which demonstrates high energy efficiency and high throughput advantage. We find that the high-throughput and high-speed performance of RSFQ circuits can take the advantage of a hardware implementation of the encryption algorithm, whereas these are rarely applied to this field. Among the available encryption algorithms, the advanced encryption standard (AES) algorithm is an advanced encryption standard algorithm. It is currently the most widely used symmetric cryptography algorithm. In this work, we aim to demonstrate the SubByte operation of an AES-128 algorithm using RSFQ circuits based on the SIMIT Nb03 process. We design an AES S-box circuit in the RSFQ logic, and compare its operational frequency, power dissipation, and throughput with those of the CMOS-based circuit post-simulated in the same structure. The complete RSFQ S-box circuit costs a total of 42237 Josephson junctions with nearly 130 Gbps throughput under the maximum simulated frequency of 16.28 GHz. Our analysis shows that the frequency and throughput of the RSFQ-based S-box are about four times higher than those of the CMOS-based S-box. Further, we design and fabricate a few typical modules of the S-box. Subsequent measurements demonstrate the correct functioning of the modules in both low and high frequencies up to 28.8 GHz.

Sulfate radicals produced by ultrasonic activation of persulfate (PS) or sulfate were applied to disintegrate sludge flocs and extracellular polymeric substances (EPSs). The pretreatment facilitated the production of volatile fatty acids (VFAs) and hydrogen from subsequent anaerobic fermentation, yielding a potential method for improving the utilization of sulfate-containing waste-activated sludge (WAS). Sulfate radicals produced using ultrasound (US) in the presence of PS/sulfate showed a synergetic effect of advanced oxidation on WAS pretreatment. Among the three types of pretreatment (US, US + Sulfate, and US + PS), US + PS pretreatment was the most favoured for chemical oxygen demand (COD) solubilization, protein release, and sludge disintegration under a US density of 1.5 W/mL. Tightly bound EPS (TB-EPS) could be effectively disintegrated, and organic compounds were transformed into loosely bound EPS and soluble EPS. Unexpected COD consumption by excessive free radicals was also observed, when increasing the ultrasonic energy input (e.g. to 12 W/mL), towards a positive role for sludge disintegration and subsequent anaerobic fermentation. It was found that small particles (0.1–0.5 μm) from released organics could be preferentially overoxidized. An appropriate low ultrasonic strength initiated attack on the polymeric substances in WAS by the produced radicals, which TB-EPS could be primary target.

Vinyl (–CHCH2) is a functional group in chlorophyll molecules that are essential in natural photosynthesis, which is crucial for tuning the electronic properties and the interaction between chlorophyll and other biological cofactors. Approaches to apply a vinyl group in artificial photosynthesis have been reported to improve the electron transfer from an iridium complex photosensitizer (PS) to a colloidal platinum catalyst likely by chemical adsorption. However, versatile molecular design of Ir-PSs utilizing a vinyl group is still very important to further develop photocatalytically active compounds. Here we report two new Ir-PSs with a phenylvinyl (styrenyl) moiety in two different positions. Their hydrogen-generation performance was assessed in the presence of a triethylamine electron donor and a colloidal platinum catalyst. As expected, both the Ir-PSs show much higher turnover numbers than the non-styrenylic Ir-PS, and interestingly, the H2 generation longevity was clearly observed to be dependent on the styrenyl position.

RDX and HMX are widely used energetic materials and they are recognized as environmental contaminants at numerous locations. The present study investigated the biotransformation of RDX and HMX by anaerobic granular sludge under sulfate- and nitrate-enriched conditions. The results showed that RDX and HMX could be transformed by anaerobic granular sludge when nitrate was present. However, the biotransformation of RDX and HMX was negatively influenced, especially with high nitrate concentrations. Sulfate-enriched conditions were more favorable for the removal of ammunition compounds by anaerobic granular sludge than nitrate-enriched conditions. The removal of RDX and HMX under both nitrate- and sulfate-enriched conditions was facilitated by the use of glucose as additional substrate. This knowledge may help identify factors required for rapid removal of RDX and HMX in high-rate bioreactors. These results can also be applied to devise an appropriate and practical biological treatment strategy for explosive contaminated wastewater.

Calcium carbonate often precipitates in anaerobic reactors treating wastewater with high calcium content. The aim of this paper is to study the effect of wastewater composition on calcium carbonate precipitation in upflow anaerobic sludge blanket (UASB) reactors. Two laboratory-scale UASB reactors were operated with calcium-containing influents using acetate and carbohydrate as substrate, respectively. There was an obvious accumulation of inorganic precipitate observed in the biogranules. Observations via scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) showed that the acclimated biogranules in the two reactors differed in microstructure. Calcium carbonate was found to have precipitated on the surface of acetate-degrading biogranules, but precipitated at the core of the carbohydrate-degrading biogranules. The results indicated that substrates had significant influence on the location of calcium carbonate precipitation in anaerobic granular sludge, which was expected due to the different methanogens distribution and pH gradient within the granular sludge degrading various substrates. Moreover, the location of calcium carbonate precipitation substantially affected the specific methanogenic activity (SMA) of the granular sludge. The SMA of the acetate-degrading biogranules dropped from \( 1.96 gCOD_{CH_4 } \cdot gVSS^{ - 1} \cdot d^{ - 1} \) to \( 0.61 gCOD_{CH_4 } \cdot gVSS^{ - 1} \cdot d^{ - 1} \) after 180-d of operation in the reactor. However, the SMA of the carbohydrate-degrading biogranules was not adversely affected by calcium carbonate precipitation.

BACKGROUND: This study investigated the performance of anaerobic mesophilic granular sludge for the degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Batch tests were conducted to investigate the effects of different supplements on the RDX degradation ability of anaerobic granular sludge, as well as the contributions of both physicochemical and biological processes involved in RDX removal from aqueous solution. RESULTS: Anaerobic granular sludge exhibited good performance in treating RDX as the sole substrate. Biodegradation was the main mechanism responsible for RDX removal. Ammonium had no significant promoting effect on the degradation process. The presence of glucose was found to enhance the degradation of RDX by anaerobic granular sludge, while the addition of sulfate and nitrate had adverse effects on the reductive transformation of RDX. CONCLUSIONS: Anaerobic granular sludge is capable of removing RDX from aqueous solution with high efficiency. This study showed good prospects for high-rate anaerobic processes in the treatment of munition wastewater. The results can be used for the design and optimization of high rate anaerobic systems for the elimination of RDX. Copyright © 2010 Society of Chemical Industry

The filtration performances of submerged membrane bioreactors (SMBR) with and without the addition of powdered activated carbon (PAC) were investigated respectively under the same feed and operation conditions. A series of experiments were conducted to analyze near-critical flux, effect of air-scouring rate and time of stable filtration operation of both systems. The experimental results demonstrated that pronounced flux enhancement was achieved by adding 1.2 g/L PAC. The near-critical flux for the biological powdered activated carbon (BPAC) system was about 32% higher than that for the activated sludge (AS) system. Increasing the air-scouring rate led to a more significant flux improvement for the BPAC system compared to the AS system. Long-term operation indicated that, at constant flux, the TMP increasing rate of the BPAC system could be lagged and thus cause the extension of operating intervals about 1.8 times compared to the AS system. Quantitative calculations showed the total hydraulic resistance of the BPAC system was about 44% lower than that of the AS system, and this decrease was mainly caused by the reduction in cake resistance. Analyses were then made from various aspects such as floc size distribution and apparent viscosity of the mixed liquor to elucidate the major factors giving rise to different filtration characteristics.

Two lab scale upflow anaerobic sludge bed (UASB) reactors were operated at an organic loading rate of COD 9 kg x (m3 x d)(-1) to treat two kinds of calcium containing wastewaters, one of which took acetic acid as substrate and for the other, glucose and soluble starch were the substrate. Both the wastewaters contained 800 mg x L(-1) Ca+. Precipitation of calcium carbonate in the reactors was observed. The results showed that the kind of substrate had great influence on calcium carbonate precipitation. In the reactor treating acetic acid containing wastewater, a maximum calcium precipitation rate of 65% was achieved and an average rate of about 25% was then maintained. In contrast, the calcium precipitation rate for the glucose and soluble starch containing wastewater was only about 7.5%. It was also found that substantial precipitation only occurred 30 days after the reactor were operated for both of the wastewaters. After 180 days of operation, the ash content of the sludge in the reactors increased from about 10% to 70% for the acetic acid containing wastewater and 30% for the other. However, the increase of ash content had no negative influence on the COD removal efficiency, which was kept at about 90% throughout the experimental period. By the SEM it was inferred that the different substrates caused the differences of the granular sludge microstructure, leading to the diversity of calcium carbonate precipitation in the two reactors.

In this study, the expansion characteristics of an anaerobic granular bed in EGSB reactors based on terminal settling velocity study of the granules and the Richardson-Zaki equation (1954) have been investigated. The settling velocity study shows that the mean settling velocity of the granules is in accordance with the Allen formula because the settling process falls within the intermediate flow regime range (1 Water SA Vol.32 (4) 2006: pp.555-560

Mean settling velocity of granular sludge in full-scale UASB (upflow anaerobic sludge blanket) and EGSB (expanded granular sludge bed) reactors was evaluated by settling column tests, and a settling velocity model based on the experimental results and available literature data was developed. It is concluded that the settling velocity should be calculated by the Allen formula, because the settling process of the granules is in the category of intermediate flow regime rather than in the laminar flow one. The comparison between calculated and measured values of the settling velocity shows an excellent agreement, with an average relative error of 4.04%. A simple but reliable mathematical method to determine the settling velocity is therefore proposed.