Inverse design of metasurface based off-axis image relay.

The rapid advancement of portable electronics has created enormous demand for compact optical imaging systems. Such systems often require folded optical systems with beam steering and shaping components to reduce sizes and minimize image aberration at the same time. In this study, we present a solution that utilizes an inverse-designed dielectric metasurface for arbitrary-angle image-relay with aberration correction. The metasurface phase response is optimized by a series of artificial neural networks to compensate for the severe aberrations in the deflected images and meet the requirements for device fabrication at the same time. We compare our results to the solutions found by the global optimization tool in Zemax OpticStudio and show that the proposed method can predict better point-spread functions and images with less distortion. Finally, we designed a metasurface to achieve the optimized phase profile.

Achieving Carbon Mitigation with Economic Benefits through High-Resolution Analysis of Renewable Resource Integration in Global Coastal Cities.

Coastal regions, home to more than half of the global population and contributing over 50% to the global economy, possess vast renewable resources, such as seawater and solar energy. The effective utilization of these resources, through the seawater-cooled district cooling system (SWDCS), seawater toilet flushing (SWTF), and rooftop solar photovoltaic system (RTPV), has the potential to significantly reduce carbon emissions. However, implementing these technologies in different geographic contexts to achieve the desired carbon and economic outcomes at the city level lacks a clear roadmap. To address this challenge, we comprehensively analyzed 12 coastal megacities worldwide by integrating geospatial building data. Our study evaluated the potential energy savings, carbon mitigation, and levelized carbon abatement costs (LCACs) from a life cycle perspective. The results revealed that using seawater and solar energy within urban boundaries can reduce electricity consumption from 1 to 24% across these cities. The spatial distribution of the LCAC for seawater-based systems exhibited more variation compared to the RTPV. By applying specific LCAC thresholds ranging from 0 to 225 USD/tCO2e, all cities could achieve both carbon reductions and economic benefits. These thresholds resulted in up to 80 million tonnes of carbon emission reductions and 5 billion USD of economic benefits, respectively. Our study provides valuable insights into integrating renewable resource systems, enabling coastal cities to achieve carbon and economic advantages at the city scale simultaneously.

Contributions of Pharmaceuticals to DBP Formation and Developmental Toxicity in Chlorination of NOM-containing Source Water.

Pharmaceuticals have been considered a priority group of emerging micropollutants in source waters in recent years, while their role in the formation and toxicity of disinfection byproducts (DBPs) during chlorine disinfection remains largely unclear. In this study, the contributions of natural organic matter (NOM) and pharmaceuticals (a mixture of ten representative pharmaceuticals) to the overall DBP formation and toxicity during drinking water chlorination were investigated. By innovatively "normalizing" chlorine exposure and constructing a kinetic model, we were able to differentiate and evaluate the contributions of NOM and pharmaceuticals to the total organic halogen (TOX) formation for source waters that contained different levels of pharmaceuticals. It was found that at a chlorine contact time of 1.0 h, NOM (2 mg/L as C) and pharmaceuticals (total 0.0062-0.31 mg/L as C) contributed 79.8-99.5% and 0.5-20.2%, respectively, of TOX. The toxicity test results showed that the chlorination remarkably increased the toxicity of the pharmaceutical mixture by converting the parent compounds into more toxic pharmaceutical-derived DBPs, and these DBPs might contribute significantly to the overall developmental toxicity of chlorinated waters. This study highlights the non-negligible role of pharmaceuticals in the formation and toxicity of overall DBPs in chlorinated drinking water.

Flushing Toilets and Cooling Spaces with Seawater Improve Water-Energy Securities and Achieve Carbon Mitigations in Coastal Cities.

Exploring alternative water sources and improving the efficiency of energy uses are crucial approaches to strengthening the water-energy securities and achieving carbon mitigations in sub(tropical) coastal cities. Seawater use for toilet flushing and district cooling systems is reportedly practical for achieving multiaspect benefits in Hong Kong. However, the currently followed practices are yet to be systematically evaluated for scale expansions and system adaptation in other coastal cities. The significance of using seawater to enhance local water-energy securities and carbon mitigations in urban areas remains unknown. Herein, we developed a high-resolution scheme to quantify the effects of the large-scale urban use of seawater on a city's reliance on non-local and non-natural water and energy supplies and its carbon mitigation goals. We applied the developed scheme in Hong Kong, Jeddah, and Miami to assess diverse climates and urban characteristics. The annual water and energy saving potentials were found to be 16-28% and 3-11% of the annual freshwater and electricity consumption, respectively. Life cycle carbon mitigations were accomplished in the compact cities of Hong Kong and Miami (2.3 and 4.6% of the cities' mitigation goals, respectively) but not in a sprawled city like Jeddah. Moreover, our results suggest that district-level decisions could result in optimal outcomes supporting seawater use in urban areas.

Nomograms for predicting survival in patients with micropapillary bladder cancer: a real-world analysis based on the surveillance, epidemiology, and end results database and external validation in a tertiary center.

BACKGROUND: The present study aimed to construct and validate nomograms that can be used to predict cancer-specific survival (CSS) and overall survival (OS) in patients with micropapillary bladder cancer. METHODS: The data of 627 patients diagnosed with micropapillary bladder cancer between 2000 and 2018 were obtained from the surveillance, epidemiology, and end results database. Patients were randomly divided into the training and internal validation sets (7:3). The Cox proportional hazards regression model was applied to evaluate the association between variables and survival and then nomograms were constructed to predict the survival of an individual patient. The performance of nomograms was validated by using calibration curves, concordance index, receiver operating characteristic curves with the calculated area under the curve and decision curve analysis in the training and internal validation set. Data from 41 micropapillary bladder cancer patients at Qilu Hospital of Shandong University from 2000 to 2022 were collected for external validation. RESULTS: Several independent risk factors were taken into the two nomograms (CSS and OS), including age, marital status, AJCC TMN stage, surgical approach, lymph node ratio, and tumor size while the OS nomogram additionally contained race. The concordance index of the training set, internal validation set, and external verification set were all over 0.7. The calibration curve indicated good consistence between the nomogram prediction and actual survival. Area under the curve and decision curve analysis results indicated great clinical usefulness of nomograms. CONCLUSIONS: The nomograms predicting the survival outcome of patients with micropapillary bladder cancer would provide a valuable tool to help clinicians to evaluate the risk of patients and make individual treatment strategies.

Fourier Optical Spin Splitting Microscopy.

In this Letter, we propose a new quantitative phase imaging methodology named Fourier optical spin splitting microscopy (FOSSM). FOSSM relies on a metasurface located at the Fourier plane of a polarized microscope to separate the object image into two replicas of opposite circularly polarized states. The bias retardation between the two replicas is tuned by translating the metasurface or rotating the analyzer. Combined with a polarized camera, FOSSM can easily achieve single-shot quantitative phase gradient imaging, which greatly reduces the complexity of current phase microscope setups, paving the way for the next generation high-speed real-time multifunctional microscopy.

Hydrazine Detection during Ammonia Electro-oxidation Using an Aggregation-Induced Emission Dye.

Ammonia electro-oxidation is an extremely significant reaction with regards to the nitrogen cycle, hydrogen economy, and wastewater remediation. The design of efficient electrocatalysts for use in the ammonia electro-oxidation reaction (AOR) requires comprehensive understanding of the mechanism and intermediates involved. In this study, aggregation-induced emission (AIE), a robust fluorescence sensing platform, is employed for the sensitive and qualitative detection of hydrazine (N2H4), one of the important intermediates during the AOR. Here, we successfully identified N2H4 as a main intermediate during the AOR on the model Pt/C electrocatalyst using 4-(1,2,2-triphenylvinyl)benzaldehyde (TPE-CHO), an aggregation-induced emission luminogen (AIEgen). We propose the AOR mechanism for Pt with N2H4 being formed during the dimerization process (NH2 coupling) within the framework of the Gerischer and Mauerer mechanism. The unique chemodosimeter approach demonstrated in this study opens a novel pathway for understanding electrochemical reactions in depth.

Comparative metabolic modeling of multiple sulfate-reducing prokaryotes reveals versatile energy conservation mechanisms.

Sulfate-reducing prokaryotes (SRPs) are crucial participants in the cycling of sulfur, carbon, and various metals in the natural environment and in engineered systems. Despite recent advances in genetics and molecular biology bringing a huge amount of information about the energy metabolism of SRPs, little effort has been made to link this important information with their biotechnological studies. This study aims to construct multiple metabolic models of SRPs that systematically compile genomic, genetic, biochemical, and molecular information about SRPs to study their energy metabolism. Pan-genome analysis was conducted to compare the genomes of SRPs, from which a list of orthologous genes related to central and energy metabolism was obtained. Twenty-four SRP metabolic models via the inference of pan-genome analysis were efficiently constructed. The metabolic model of the well-studied model SRP Desulfovibrio vulgaris Hildenborough (DvH) was validated via flux balance analysis (FBA). The DvH model predictions matched reported experimental growth and energy yields, which demonstrated that the core metabolic model worked successfully. Further, steady-state simulation of SRP metabolic models under different growth conditions showed how the use of different electron transfer pathways leads to energy generation. Three energy conservation mechanisms were identified, including menaquinone-based redox loop, hydrogen cycling, and proton pumping. Flavin-based electron bifurcation (FBEB) was also demonstrated to be an essential mechanism for supporting energy conservation. The developed models can be easily extended to other species of SRPs not examined in this study. More importantly, the present work develops an accurate and efficient approach for constructing metabolic models of multiple organisms, which can be applied to other critical microbes in environmental and industrial systems, thereby enabling the quantitative prediction of their metabolic behaviors to benefit relevant applications.

Biofilm development in a pilot-scale gravity sewer: Physical characteristics, microstructure, and microbial communities.

The existence of abundant biofilms on sewer pipeline walls can lead to negative environmental impacts, such as poisonous gas release and pipe corrosions through transforming various pollutants. Investigating the formation process of sewer biofilms is of importance in advancing knowledge of sewer operation and maintenance. In this study, the changes in physical characteristics, microstructure, and microbial communities of sewer biofilm were analyzed in-depth in a pilot-scale gravity sewer during a 45-day operation. The results show that a high specific surface area at the early stage could channel the substrates for stimulating the primary colonizers (e.g., Cytophagia, Sphingobacteriia, Alpha-, and Betaproteobacteria), which could excrete an extracellular matrix to facilitate biofilm growth. The sewer biofilms were gradually formed with 62 g VS/m2 organic content, 1.2 mm biofilm thickness, and 89 mg/cm3 dry density after 45 days operation. Moreover, the biofilm growth promoted the emergence of facultative bacteria and anaerobes (affiliated with Flavobacteriia, Gemmatimonadetes, Deltaproteobacteria, and Epsilonproteobacteria). Microelectrode analysis further verified that an anaerobic zone existed in mature biofilm with a negative oxidation-reduction potential (-105 mV), where approximately 0.1 µmol/L of sulfide was produced. Our results suggest that the migration of the microbial community correlated with the changes in the evolved physical characteristics and microstructure of sewer biofilm, and this can contribute to the strategies for sulfide control for improving sewer maintenance.

Single-chip holographic beam steering for lidar by a digital micromirror device with angular and spatial hybrid multiplexing.

A digital micromirror device (DMD) based holographic beam steering technique is reported that multiplexes fine-steering binary amplitude gratings with a coarse-steering programmable blazed grating. The angular spatial light modulation (ASLM) technique encodes the spatial pattern of the binary amplitude grating at the same plane as the angular modulation set by a phase map of the DMD-based beam steering technique. The beam steering technique is demonstrated at 532 nm and implemented into a 905 nm lidar system. The results of the lidar system tests are presented, achieving a 44° field-of-view, 0.9°×0.4° (H×V) angular resolution, 1 m max distance, 1.5 kHz sampling, and 7.8 FPS video. Scalability techniques are proposed, including max distance increases to over 100 m.

Wide-angle MEMS-based imaging lidar by decoupled scan axes.

We present an optical architecture for a scanning lidar in which a digital micromirror device (DMD) is placed at an intermediate image plane in a receiver to decouple the trade-offs between scan angle, scan speed, and aperture size of the lidar's transmitter and receiver. In the architecture, the transmitter with a galvo mirror and the receiver with a DMD scan the horizontal and vertical fields of view, respectively, to enable an increased field of view of 50°, centimeter transmitter beam diameter, and video frame rate range finding captures. We present our optimized system and discuss the adjustable parameter trade-offs.

Test of transformation mechanism of food waste and its impacts on sulfide and methane production in the sewer system.

Food waste (FW) management has become an important issue worldwide. Diverting FW into the sewer system is considered promising to tackle the FW issue. However, the transformation of FW in sewers and its impact on the sewer process have not received adequate attention due to the overlooked sewer networks. In this study, a laboratory-scale sewer reactor system was established to investigate the transformation of FW and the production of sulfide and methane under anaerobic conditions. The transformation of FW in the sewer reactor could result in an increase in the substrate level through hydrolyzing and converting biodegradable substances into preferred substrates. Moreover, the generated substrates from the addition of FW were preferable for the metabolism of key microbes in sewer biofilms. As a result, methane production from the sewer reactor could be enhanced from the addition of FW, whereas sulfide production was not affected at a low sulfate concentration. The findings of this study suggest that the diversion of FW may exert an adverse impact on sewers and the environment in terms of greenhouse gas emission. Hence, more research is necessary to clarify the detailed impacts on FW management and wastewater treatment.

Electrochemical Pretreatment for Sludge Sulfide Control without Chemical Dosing: A Mechanistic Study.

Sulfide is a toxic and corrosive odorant generated in various sludge treatment and disposal systems. We developed an electrochemical pretreatment (EPT) approach to eliminate sludge sulfide production without adding chemicals. Biochemical sulfide potential (BSP) test was used to evaluate the effectiveness of EPT on sludge sulfide production. The sulfide control was effective with EPT, and we determined the underlying mechanism of EPT. EPT which was operated at 12 V for 720 s eliminated 99% of dissolved sulfide and 100% of gaseous H2S(g). In comparison, the dissolved sulfide reached 104 ± 1 mg S/L in the control BSP test. A sulfur mass balance analysis in the BSP test showed that 90% of the produced sulfide was removed via metal precipitation. Metal distribution results confirmed that metals (i.e., Fe, Mn, and Ni) in the sludge became soluble after EPT and were released from their residual and organically bound fractions. EPT which was operated at 15 V solubilized around 73, 92, and 72% of Fe, Mn, and Ni, and these metals precipitated the sulfide that was produced from biological sulfate reduction. Sludge analysis revealed that EPT disintegrated sludge flocs and disrupted metal-binding functional groups. Specifically, reduction of 17% C═O functional groups in the sludge was found, which could be associated with metal release. The impact of oxidants (e.g., chlorine) generated from EPT on sulfide oxidation was minimal. The findings of this study broadened up our understanding of the electrochemical process for sulfide control during saline sludge digestion.

Biological nitrogen removal from wastewater using sulphur-driven autotrophic denitrification.

Biological denitrification process in mainstream wastewater treatment often needs dosing supplemental electrons, consequently adding a remarkable operating cost. Organic carbon compounds are nowadays the most intensively used electron sources in full-scale wastewater treatment, corresponding with the well-understood carbon-nitrogen biogeochemistry for heterotrophic denitrification process. In the twenty-first century, the low-carbon technology is on calling to reduce the carbon footprint and relieve climate changing threatens. Autotrophic denitrification is highly recommended for mainstream wastewater treatment. The reduced-sulphur compounds (such as sulphide, elemental sulphur, and thiosulphate) could be utilised as electron donors, to drive sulphur cycle reactions to reduce nitrate and nitrite to dinitrogen gas. Based on the literature review and our own research experiences, this paper presents our perspectives on sulphur-driven autotrophic denitrification. It particularly focuses on the functional enzymes, sulphur bioreactors, and influential operating factors. Overall, this paper provides new insights on sulphur-nitrogen biogeochemistry and application as a low-carbon technology for nitrogen removal during municipal wastewater treatment.

Long-Term Feeding of Elemental Sulfur Alters Microbial Community Structure and Eliminates Mercury Methylation Potential in Sulfate-Reducing Bacteria Abundant Activated Sludge.

This study reported a novel observation that the long-term cultivation of sulfur-reducing bacteria (S0RB) from a sulfate-reducing bacteria (SRB)-abundant seeding sludge with elemental sulfur feeding significantly shaped the microbial community structure and eliminated the mercury methylation potential in the S0RB-enriched sludge. In this study, the enrichments of SRB and S0RB from activated sludge were obtained through long-term cultivations. Subsequently, the batch tests showed that approximately 5000 µg/L Hg (II) was completely removed from the solution by both the SRB-enriched and S0RB-enriched sludge. Extremely low or no MeHg production was observed in the S0RB-enriched sludge (less than the limit of detection, 0.01 µg/L), while 1.49 µg/L MeHg accumulated in the SRB-enriched sludge. Other batch tests using the sludge samples from a replication of the cultivation showed that the methylation capability of the S0RB-enriching sludge gradually diminished to a negligible level over a 6 month cultivation time. However, some mercury-methylation-related bacteria were present in the enrichment of S0RB such as Geobacter. The absence of MeHg in the S0RB-enriched sludge may be attributed to the dissolved organic matter (DOM) instead of the sulfur- and sulfate-reduction pathway or MeHg demethylation when exposed to Hg (II). The cultivated S0RB could be used for mercury-contaminated wastewater treatment without MeHg concern.

Sludge flotation, its causes and control in granular sludge upflow reactors.

Sludge flotation is a commonly reported and long-standing issue hindering not only the widespread implementation of upflow anaerobic sludge bed (UASB)-type bioreactors in wastewater treatment but also the development of novel anaerobic/anoxic treatment processes such as anammox, partial denitrification, and biological sulfate reduction. This review attempts to address the instability of UASB-type bioreactors due to sludge flotation. Possible causes of sludge flotation are classified into intrinsic and extrinsic ones. Extrinsic causes include substrate overloading, inappropriate carbon source, overloading of proteins or oils, insufficient reactor mixing, a low temperature, and a low pH. These unfavorable extrinsic conditions can lead to unexpected intrinsic changes in sludge granules, including high gas production, formation of hollow space inside the granules, filamentous bacterial overgrowth, inappropriate production of extracellular polymeric substances, and development of an adhesive granule surface. These intrinsic changes can increase the flotation potential of sludge through reducing the granule density and promoting gas entrapment. To control the sludge flotation problem, both preventive and corrective strategies are summarized. Preventive strategies include maintaining a temperature of 30-35 °C and a pH of 7-9, preventing substrate overloading, providing sufficient nutrients and multiple carbon sources in the influent, applying pre-acidification, and enhancing reactor mixing. If the causes of a sludge flotation incident cannot be identified quickly, corrective strategies including breaking up floating granules and dosing with chemicals such as Fe2+ and surfactants can be applied to suppress the flotation problem.

Application of a moving-bed biofilm reactor for sulfur-oxidizing autotrophic denitrification.

Sulfur-oxidizing autotrophic denitrification (SO-AD) was investigated in a laboratory-scale moving-bed biofilm reactor (MBBR) at a sewage temperature of 22 °C. A synthetic wastewater with nitrate, sulfide and thiosulfate was fed into the MBBR. After 20 days' acclimation, the reduced sulfur compounds were completely oxidized and nitrogen removal efficiency achieved up to 82%. The operation proceeded to examine the denitrification by decreasing hydraulic retention time (HRT) from 12 to 4 h in stages. At steady state, this laboratory-scale SO-AD MBBR achieved the nitrogen removal efficiency of 94% at the volumetric loading rate of 0.18 kg N·(mreactor3·d)-1. The biofilm formation was examined periodically: the attached volatile solids (AVS) gradually increased corresponding to the decrease of HRT and stabilized at about 1,300 mg AVS·Lreactor-1 at steady state. This study demonstrated that without adding external organic carbon, SO-AD can be successfully applied in moving-bed carriers. The application of SO-AD MBBR has shown the potential for sulfur-containing industrial wastewater treatment, brackish wastewater treatment and the upgrading of the activated sludge system. Moreover, the study provides direct design information for the full-scale MBBR application of the sulfur-cycle based SANI process.

A novel approach to quantifying elemental sulfur (S0) in environmental samples.

The quantification of elemental sulfur (S0) is an important part of monitoring and controlling sulfur-involving processes. Existing methods of S0 detection either require significant time or involve the use of toxic chemicals. We have developed and validated a new method to determine S0 in environmental samples using calorimeter-ion chromatography (IC), in which S0 is fully oxidized to sulfur trioxide (SO3) with pure oxygen at 20 atm in a calorimeter. The resulting SO3 is then absorbed by a sodium bicarbonate (NaHCO3) solution and analyzed using IC. To verify this method, standard samples with various sulfur contents (5-200 mg S), possible interfering substances (SO42-, SO32-, S2O32- and S2-), and mixed environmental samples were tested and compared. The high correlation of R2 = 0.999 between the examined and theoretical values was obtained with a high recovery rate of ≥95% and a low relative standard deviation (RSD) of ≤1%. Samples containing at least 25 mg of S0 were accurately measured (recovery error < 5%). Thiosulfate was identified as the main interfering substance, and pretreatment was needed to eliminate it. This new method is more efficient, cost-effective, easier to operate, and more secure and accurate than existing methods.

Investigation on the anaerobic co-digestion of food waste with sewage sludge.

In this laboratory-scale investigation on the applicability of the co-digestion of food waste with sewage sludge, evaluated were the effects of the single-stage versus two-stage operating modes at the hydraulic retention time (HRT) of 15 days, and the impact of HRTs: 15 days vs. 25 days, on the single-stage operation. An average volatile solid reduction (VSR) of 61% and methane yield of 314 ml/g-VS were achieved in the two-stage operation (HRT 15 days), while comparable VSR of 57% and the methane yield of 325 ml CH4/g-VS could only be detected at a longer HRT at 25 days in the single-stage operation. The difference in the operating modes showed much higher influence on shaping the overall bacterial structures than the two HRTs of the single-stage operation. The one operational taxonomic unit (OTU) annotatable at the family level of Thermotogaceae was most abundant (> 10%) in all the methanogenic co-digestion consortia, and its dominant role was recognized to be independent of other OTU lineages in the community. OTUs in the phylum Proteobacteria were much more common as the persistent OTUs in the single-stage co-digestion consortia, while in the two-stage consortia, they were in the phylum Firmicutes. Annotation on the functional genes suggested that the phylum Firmicutes hosted the majority of pilus genes and hydrogenase genes that were reported to be essential for the syntrophic conversion of the high concentrations of alcohols and reduced fatty acids in the methanogenic reactor operated under the two-stage mode.

Characterization and Performance of Hollow Silica for Adsorption of Amoxicillin in Aqueous Solutions.

Two kinds of hollow silica materials, namely H-SiS1 and H-SiS2, were synthesized using the yeast template method and the Pickering emulsion polymerization method, respectively. The adsorbents were synthesized to adsorb amoxicillin (AMX) from an aqueous environment. Characterization results indicated that hollow silica adsorbents exhibited excellent thermal stability even at temperatures above 700 °C. Several batches of static adsorption experiments were prepared to analyze the adsorption performance on AMX. Isotherm data on different adsorbents fitted well with the Langmuir model (from 15 °C to 35 °C), indicating a monolayer molecular adsorption mechanism for AMX. The maximum adsorption capacities of H-SiS1 and H-SiS2 were 8.40 and 3.46 mg/g at 35 °C, respectively. The adsorption kinetics was described well by the pseudo-second-order model, which indicated that chemical interactions were primarily responsible for AMX adsorption and could be the rate-limiting step during adsorption. These results suggested that H-SiS1 could be significantly useful as adsorbents for removal of AMX residuals from aqueous solution.