Validity, feasibility, and effectiveness of a voice-recognition based digital cognitive screener for dementia and mild cognitive impairment in community-dwelling older Chinese adults: A large-scale implementation study.

INTRODUCTION: We investigated the validity, feasibility, and effectiveness of a voice recognition-based digital cognitive screener (DCS), for detecting dementia and mild cognitive impairment (MCI) in a large-scale community of elderly participants. METHODS: Eligible participants completed demographic, cognitive, functional assessments and the DCS. Neuropsychological tests were used to assess domain-specific and global cognition, while the diagnosis of MCI and dementia relied on the Clinical Dementia Rating Scale. RESULTS: Among the 11,186 participants, the DCS showed high completion rates (97.5%) and a short administration time (5.9 min) across gender, age, and education groups. The DCS demonstrated areas under the receiver operating characteristics curve (AUCs) of 0.95 and 0.83 for dementia and MCI detection, respectively, among 328 participants in the validation phase. Furthermore, the DCS resulted in time savings of 16.2% to 36.0% compared to the Mini-Mental State Examination (MMSE) and Montral Cognitive Assessment (MoCA). DISCUSSION: This study suggests that the DCS is an effective and efficient tool for dementia and MCI case-finding in large-scale cognitive screening. HIGHLIGHTS: To our best knowledge, this is the first cognitive screening tool based on voice recognition and utilizing conversational AI that has been assessed in a large population of Chinese community-dwelling elderly. With the upgrading of a new multimodal understanding model, the DCS can accurately assess participants' responses, including different Chinese dialects, and provide automatic scores. The DCS not only exhibited good discriminant ability in detecting dementia and MCI cases, it also demonstrated a high completion rate and efficient administration regardless of gender, age, and education differences. The DCS is economically efficient, scalable, and had a better screening efficacy compared to the MMSE or MoCA, for wider implementation.

2D Ruthenium-Chromium Oxide with Rich Grain Boundaries Boosts Acidic Oxygen Evolution Reaction Kinetics.

Ruthenium oxide is currently considered as the promising alternative to Ir-based catalysts employed for proton exchange membrane water electrolyzers but still faces the bottlenecks of limited durability and slow kinetics. Herein, a 2D amorphous/crystalline heterophase ac-Cr0.53 Ru0.47 O2-δ substitutional solid solution with pervasive grain boundaries (GBs) is developed to accelerate the kinetics of acidic oxygen evolution reaction (OER) and extend the long-term stability simultaneously. The ac-Cr0.53 Ru0.47 O2-δ shows a super stability with a slow degradation rate and a remarkable mass activity of 455 A gRu -1 at 1.6 V vs RHE, which is ≈3.6- and 5.9-fold higher than those of synthesized RuO2 and commercial RuO2 , respectively. The strong interaction of Cr-O-Ru local units in synergy with the specific 2D structural characteristics of ac-Cr0.53 Ru0.47 O2-δ dominates its enhanced stability. Meanwhile, high-density GBs and the shortened Ru-O bonds tailored by amorphous/crystalline structure and Cr-O-Ru interaction regulate the adsorption and desorption rates of oxygen intermediates, thus accelerating the overall acidic OER kinetics.

Synergistic Effect of Grain Boundaries and Oxygen Vacancies on Enhanced Selectivity for Electrocatalytic CO2 Reduction.

Dual-engineering involved of grain boundaries (GBs) and oxygen vacancies (VO ) efficiently engineers the material's catalytic performance by simultaneously introducing favorable electronic and chemical properties. Herein, a novel SnO2 nanoplate is reported with simultaneous oxygen vacancies and abundant grain boundaries (V,G-SnOx /C) for promoting the highly selective conversion of CO2 to value-added formic acid. Attributing to the synergistic effect of employed dual-engineering, the V,G-SnOx /C displays highly catalytic selectivity with a maximum Faradaic efficiency (FE) of 87% for HCOOH production at -1.2 V versus RHE and FEs > 95% for all C1 products (CO and HCOOH) within all applied potential range, outperforming current state-of-the-art electrodes and the amorphous SnOx /C. Theoretical calculations combined with advanced characterizations revealed that GB induces the formation of electron-enriched Sn site, which strengthens the adsorption of *HCOO intermediate. While GBs and VO synergistically lower the reaction energy barrier, thus dramatically enhancing the intrinsic activity and selectivity toward HCOOH.

Cost-benefit and discriminant validity of a stepwise dementia case-finding approach in an Asian older adult community.

Background: Case-finding is a recommended approach for dementia early detection in the community. Aims: To investigate the discriminant validity and cost-effectiveness of a stepwise dementia case-finding approach in a Singaporean older adult community. Methods: The two-phase study was conducted in the community from 2009 to 2015 in Singapore. A total of 3780 participants (age ≥60 years) completed phase I (a brief cognitive screening); 918 completed phase II and were included in the final analysis. In phase I, all participants were administered the Abbreviated Mental Test (AMT) and the Progressive Forgetfulness Question (PFQ). Those who screened positive on either test were invited to phase II, whereby the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA) and a formal neuropsychological battery were administered, followed by the research diagnosis of no cognitive impairment, cognitive impairment no dementia (CIND)-Mild (≤2 impaired cognitive domains), CIND-Moderate (>2 impaired domains) or dementia. Receiver operating characteristic curve analyses were conducted for the different cognitive instruments. All discriminant indices were calculated, including sensitivity, specificity, positive and negative predictive values (NPV) and accuracy. Cost-effectiveness analysis was conducted by estimating the amount of screening time needed and the number of older adults requiring re-evaluation in two case-finding scenarios, ie, with or without preselection by the PFQ. Results: The stepwise case-finding approach (preselection by the PFQ, then MMSE or MoCA or AMT) showed an excellent NPV (>99%) and accuracy (>86%) for excluding dementia-free cases. Without preselection by the PFQ, screening time for the three cognitive tools were 317.5, 317.5 and 254 hours, with 159, 302 and 175 screen-positive older adults involved in further evaluation. By adopting the stepwise case-finding approach, total screening time were 156.5, 156.5 and 126.2 hours, which decreased by 50.7%, 50.7% and 50.3% as compared with those without preselection. Furthermore, after preselection, only 98, 167 and 145 screen-positive older adults required further evaluation, corresponding to a reduction of 38.4%, 44.7% and 17.1% in the numbers compared with those without preselection. Conclusions: A stepwise approach for dementia case-finding should be implemented in the community to minimise the time and resources needed for large-scale early detection of dementia.

Associations Between Abdominal Obesity, Chewing Difficulty and Cognitive Impairment in Dementia-Free Chinese Elderly.

OBJECTIVE: To investigate the independent and synergistic associations between abdominal obesity, chewing difficulty and cognitive impairment in a community-dwelling older adults sample in China. METHODS: Cognitive function was measured by the 5 min- Montreal Cognitive Assessment (5 min-MoCA) and abdominal obesity was measured by A Body Shape Index (ABSI) in 572 participants recruited from local communities. Chewing difficulty was assessed via a self-report questionnaire. Linear regression and general logistic regression were performed to investigate the association of chewing difficulty and abdominal obesity with cognition. RESULTS: Chewing difficulty score [ß (95% CI) = -.30 (-.49, -.11)] and ABSI [ß (95%CI) = -.30 (-.55, -.05)] were independently associated with worse performance on the 5 min-MoCA. Whilst ABSI was not associated with cognitive impairment, the co-existence of chewing difficulty and abdominal obesity [OR (95% CI) = 2.22 (1.18, 4.17)] was found associated with the presence of cognitive impairment. CONCLUSION: Chewing difficulty and abdominal obesity were independently associated with cognition. Abdominal obesity and chewing may have an additive effect on cognitive function.

Design and experimental demonstration of a beam scanning lens antenna.

A beam scanning antenna based on an all-metal lens is presented for high-power microwave (HPM) application in this paper. This design includes a feed antenna and two layers of different all-metal lenses, whose prototypes operating at 14.25 GHz have been successfully designed and fabricated with an aperture radius of 300 mm. A full transmission phase range of 360° can be achieved with a transmission efficiency of over 99% by rotating the cross-slot on the lens elements. The results of the low-power tests depict that the designed antenna can realize a beam scanning range of 120° revolving cone angle with the side lobe below -10 dB and the reflection coefficient less than -16 dB. The high-power tests demonstrate that the power handling capacity of the antenna is higher than 350 MW in sulfur hexafluoride (SF6). In addition, both the designed lenses have a bandwidth of more than 100 MHz. All the merits show that our designed all-metal lens antenna has a great potential to be applied in HPM systems.

The discriminant validity of single-question assessments of subjective cognitive complaints in an Asian older adult population.

Objective: To compare the discriminant validity of three different single-question assessments of subjective cognitive complaints (SCC) for dementia in a community-based older adult population in Singapore. Methods: Eligible older adults aged ≥60 were recruited into phase I for identifying those who require further assessment using the Abbreviated Mental Test (AMT) and progressive forgetfulness question (PFQ). Participants who failed either tests entered phase II and were administered various single-question assessments of SCC, such as the 8th question on the patient Ascertain Dementia 8 (AD8-8pt), informant AD8 (AD8-8info), and the 10th item on the Geriatric Depression Scale (GDS-10), followed by the Montreal Cognitive Assessment (MoCA) and a formal neuropsychological battery to identify the participant's cognitive status by a research diagnosis and DSM-IV criteria. Differences in characteristics among diagnostic groups were compared. All discriminatory indices (sensitivity, specificity, positive, and negative predictive values, overall accuracy) for these single-question assessments and their combinations with the MoCA were calculated and reported to confirm their discriminant validity in identifying the existence of subjective complaints and objective impairment. Results: A total of 3,780 participants were assessed at phase I, of which 957 entered and completed phase II. Of whom, 911 were dementia-free and 46 had dementia. The MoCA (13/14) displayed good sensitivity (95.6%), specificity (81.5%), and overall accuracy (82.1%) for dementia detection. The GDS-10 and AD8-8pt showed poor discriminant validity, while the AD8-8info had the highest specificity (83.2%) and the greatest overall accuracy (82.5%) for dementia. Compensatory combination of the AD8-8info with MoCA, the sensitivity and positive predictive values were optimized (100%), while the conjunctive combination of two tools achieved excellent specificity (96.3%) and overall accuracy (94.8%) in discriminating dementia patients. Conclusion and implications: Combining a reliable single-question SCC assessment with an objective tool can efficiently discriminate dementia patients from healthy older adults in the community.

Prevalence, Clinical Correlates, Cognitive Trajectories, and Dementia Risk Associated With Mild Behavioral Impairment in Asians.

Objective: Mild behavioral impairment (MBI) is characterized as later-life-emergent and persistent neuropsychiatric symptoms (NPS). The symptom persistence criterion of MBI has shown to increase the signal-to-noise ratio of the syndrome, decreasing the likelihood of false-positive NPS. However, the long-term cognitive and prognostic impact of MBI remains to be evaluated against the traditional framework of NPS, especially in Asian cohorts. This study investigated the epidemiologic characteristics of MBI in a prospective clinical cohort of Singaporean elderly.Methods: A total of 304 dementia-free individuals (mean [SD] age = 72.2 [8.0] years, 51.6% female) were recruited between August 2010 and October 2019. All participants underwent annual neuropsychological, neuropsychiatric, and clinical assessments for 4 consecutive years and were diagnosed as having no cognitive impairment (NCI) or cognitive impairment-no dementia (CIND). MBI was ascertained using both baseline and year-1 Neuropsychiatric Inventory assessments. Cognitive Z-scores and Clinical Dementia Rating Sum-of-Boxes (CDR-SoB) scores were calculated.Results: The prevalence of MBI was 14.5% (7.1% of NCI, 12.9% of CIND-mild, and 24.7% of CIND-moderate patients). MBI patients showed poorer cognitive function at baseline (F1,295 = 8.13 [SE = 0.47], P = .005), primarily in memory and executive function domains. MBI was associated with accelerated decline in global cognition (ß = -0.15; 95% CI, -0.23 to -0.07) along with faster increase in CDR-SoB (ß = 0.92; 95% CI, 0.62 to 1.21) as compared to individuals without symptoms or transient NPS. A total of 38.6% of MBI patients developed dementia as compared to 12.3% of non-MBI elderly (χ2 = 19.29, P < .001). MBI increased risk of incident dementia by 2.56-fold as compared to no symptoms or transient NPS, regardless of cognitive impairment.Conclusions: MBI is a neurobehavioral risk factor for dementia, representing a potential target for dementia risk modeling, preventive intervention, and disease management.

A voice recognition-based digital cognitive screener for dementia detection in the community: Development and validation study.

Introduction: To facilitate community-based dementia screening, we developed a voice recognition-based digital cognitive screener (digital cognitive screener, DCS). This proof-of-concept study aimed to investigate the reliability, validity as well as the feasibility of the DCS among community-dwelling older adults in China. Methods: Eligible participants completed demographic, clinical, and the DCS. Diagnosis of mild cognitive impairment (MCI) and dementia was made based on the Montreal Cognitive Assessment (MoCA) (MCI: MoCA < 23, dementia: MoCA < 14). Time and venue for test administration were recorded and reported. Internal consistency, test-retest reliability and inter-rater reliability were examined. Receiver operating characteristic (ROC) analyses were conducted to examine the discriminate validity of the DCS in detecting MCI and dementia. Results: A total of 103 participants completed all investigations and were included in the analysis. Administration time of the DCS was between 5.1-7.3 min. No significant difference (p > 0.05) in test scores or administration time was found between 2 assessment settings (polyclinic or community center). The DCS showed good internal consistency (Cronbach's alpha = 0.73), test-retest reliability (Pearson r = 0.69, p < 0.001) and inter-rater reliability (ICC = 0.84). Area under the curves (AUCs) of the DCS were 0.95 (0.90, 0.99) and 0.77 (0.67, 086) for dementia and MCI detection, respectively. At the optimal cut-off (7/8), the DCS showed excellent sensitivity (100%) and good specificity (80%) for dementia detection. Conclusion: The DCS is a feasible, reliable and valid digital dementia screening tool for older adults. The applicability of the DCS in a larger-scale community-based screening stratified by age and education levels warrants further investigation.

A Time-of-Flight Estimation Method for Acoustic Ranging and Thermometry Based on Digital Lock-In Filtering.

Accurate ranging and real-time temperature monitoring are essential for metrology and safety in electrical conduit applications. This paper proposes an acoustic time-of-flight (TOF) estimation method based on the digital lock-in filtering (DLF) technique for conduit ranging and thermometry. The method establishes the relationship between the frequency and the time domain by applying a linear frequency modulated Chirp signal as the sound source and using the DLF technique to extract the first harmonic of the characteristic frequencies of the transmitted and received signals. Acoustic TOF estimation in the conduit is then achieved by calculating the mathematical expectation of the time difference between each characteristic frequency in the time-frequency relationship of the two signals. The experimental results with enhanced noise interference on different conduit lengths and various temperature conditions, proved that the proposed DLF method can establish a robust linear time-frequency relationship according to the characteristics of the Chirp signal, and the measurement accuracy of TOF has also been confirmed. Compared to the conventional method, the DLF method provides the lowest absolute error and standard deviation for both distance and temperature measurements with an enhanced robustness.

A dielectric embedded reflectarray for high-power microwave application.

To solve the problem of the large axial size of high-power microwave (HPM) reflectarray antenna and difficulty in vacuum packaging, a dielectric is introduced in the design of the antenna element. On this basis, a dielectric embedded metasurface reflectarray antenna (DEMRA) with high power handling capacity and wide-range beam scanning capability is proposed and fabricated. Compared with traditional HPM antennas, the DEMRA does not need to be sealed and can work directly in open-air conditions. The DEMRA can realize free regulation of the radiation beam within a cone angle of 90° and has a power handling capacity of 1 GW/m2. As verification, a protype working at 10 GHz is fabricated and low-power experiments are carried out. Experimental results are consistent with the simulation, proving that the DEMRA has a bandwidth exceeding 600 MHz. During the scanning process, the aperture efficiency is always higher than 48.98%, and the side lobe level remains below -15 dB. At the same time, the cross-polarization component is less than -15 dB, while the main lobe-axis ratio remains within 4.5 dB, confirming its beam scanning capability.

Enhanced Biodesulfurization with a Microbubble Strategy in an Airlift Bioreactor with Haloalkaliphilic Bacterium Thioalkalivibrio versutus D306.

Biodesulfurization under haloalkaline conditions requires limiting oxygen and additional energy in the system to deliver high mixing quality control. This study considers biodesulfurization in an airlift bioreactor with uniform microbubbles generated by a fluidic oscillation aeration system to enhance the biological desulfurization process and its hydrodynamics. Fluidic oscillation aeration in an airlift bioreactor requires minimal energy input for microbubble generation. This aeration system produced 81.87% smaller average microbubble size than the direct aeration system in a bubble column bioreactor. The biodesulfurization phase achieved a yield of 94.94% biological sulfur, 84.91% biological sulfur selectivity, and 5.06% sulfur oxidation performance in the airlift bioreactor with the microbubble strategy. The biodesulfurization conditions of thiosulfate via Thioalkalivibrio versutus D306 are revealed in this study. The biodesulfurization conditions in the airlift bioreactor with the fluidic oscillation aeration system resulted in the complete conversion of thiosulfate with 27.64% less sulfate production and 10.34% more biological sulfur production than in the bubble column bioreactor. Therefore, pleasant hydrodynamics via an airlift bioreactor mechanism with microbubbles is favored for biodesulfurization under haloalkaline conditions.

Domain-Specific Cognitive Trajectories Among Patients with Minor Stroke or Transient Ischemic Attack in a 6-Year Prospective Asian Cohort: Serial Patterns and Indicators.

BACKGROUND: Long-term post-stroke cognitive impairment (PSCI) has often been overlooked, especially among patients with minor stroke or transient ischemic attack (TIA). OBJECTIVE: To assess 6-year domain-specific cognitive trajectories among survivors of minor stroke or TIA and to identify possible indicators associated with cognitive trajectories, as well as long-term and incident PSCI. METHODS: Eligible participants completed cognitive and clinical assessments at baseline (2 weeks after stroke) and up to 5 follow-up visits in 6 years. Mixed linear models and generalized estimating equations were adopted to analyze longitudinal data and survival analysis to explore incident PSCI, controlling for demographic, clinical, and vascular indicators. RESULTS: The prevalence of PSCI and mortality rate ranged from 34.6% to 53.7%, and 0 to 7.7% respectively, among 244 patients. Incidence of PSCI was 21.9%. While visual memory demonstrated a significant improvement (p < 0.05), other cognitive domains showed a fluctuating yet stable pattern across visits (all ps > 0.05). Besides age, baseline IQCODE (attention: -0.218 SD/y, executive function: -0.238 SD/y, visual memory: -0.266 SD/y), and MoCA improvement within 1 year (visuoconstruction: 0.007 SD/y, verbal memory: 0.012 SD/y) were associated with longitudinal cognitive changes. Baseline MoCA (OR = 0.66, 95% CI = [0.59-0.74]), MoCA improvement within 3-6 months (OR = 0.79, 95% CI = [0.71-0.89], and within 1 year (OR = 0.86, 95% CI = [0.76-0.96]) were associated with long-term PSCI, while baseline MoCA (OR = 0.76, 95% CI = [0.61-0.96]) was also associated with incident PSCI. CONCLUSION: While most domains remained stable across-time, visual memory demonstrated an overall improvement. Short-term cognitive improvement could be an early indicator of long-term cognitive trajectory to identify individuals who may be resilient to PSCI.

A novel high-power waveguide phase shifter with continuous linear phase adjustment.

A novel all-metal phase shifter with continuous linear phase adjustment for high-power microwave applications is presented and tested in this paper. The phase adjustment is achieved through the rotation of a phase reverser for a circularly polarized wave, and the output phase accomplishes a phase adjustment range of 360° by rotating the phase reverser for 180°. Due to the symmetrical characteristics, its position after rotating 180° is the same as the initial position, which can achieve continuous phase adjustment and avoid phase mutation. Simulation results indicate that the phase shifter achieves the transmission efficiency greater than 99.90% at a center frequency of 8.4 GHz, and the bandwidth of transmission efficiency greater than 98.00% is up to 50 MHz. Experiments are carried out and the measured results are in good agreement with simulation. To sum up, the power capacity of this phase shifter is estimated to be more than 80 MW under vacuum conditions (<10-3 Pa), and it can be applied to fast continuous high-power beam-steerable antenna arrays or mode conversion systems.

[Determination of sulfur compounds in biological desulfurization system by high performance liquid chromatography].

Biological desulfurization is a process in which sulfur compounds are removed from gas and oil using microorganisms. It is a simple process that has mild operating conditions, high desulfurization efficiency, low energy consumption and less environmental pollution. However, there is still a lack of simple and efficient analytical methods for quantitatively analyzing the sulfur compounds in the biological desulfurization process. In order to solve this problem, the analytical method for the simultaneous determination of sulfite, thiosulfate and sulfide in biological desulfurization solutions by pre-column fluorescence derivation using high performance liquid chromatography (HPLC) was developed. The standard curves of sulfur species in this analytical method had good linear relationships with correlation coefficients of 0.999 5, 0.999 7, and 0.999 7 for sulfite, thiosulfate and sulfide, respectively. The detection limits of these sulfur compounds were 0.000 6, 0.000 7 and 0.001 1 µmol/L; the range of recovery rates were 98.17 to 101.9%, 100.9 to 102.6%, and 101.1 to 104.2%; which had good repeatability and stability. The analytical method was simple, efficient and accurate, and could be used to simultaneously determine the sulfur compounds in different biological desulfurization systems.

High-power waveguide phase shifters for phased array applications.

Two kinds of high-power waveguide phase shifters targeting the application of phased arrays are proposed in this paper. To enhance the power handling capacity, both linear phase shifters are designed to be mechanically tunable without the introduction of a dielectric and a semiconductor. For the waveguide-inserting-fin phase shifter, the phase shifting function is achieved by adjusting the length of the inserting metal fin. As for the narrow-side slot-waveguide phase shifter, the regulation of the position of the metal choke plunger placed at the end of the 3-dB power divider is used to adjust the output phase. The simulation results show that both phase shifters can realize 2π phase shift, and the transmission efficiencies are over 99% at the central frequency of 9.5 GHz. Meantime, the power handling capacity of the designed shifters is expected to be over 100 MW, which can be applied in the high-power microwave region. The slot-waveguide phase shifter is fabricated and tested along with the slotted array antenna. The experimental results coincide well with the simulations, which demonstrates the feasibility and the power capacity of the designed shifter.

Compact circular polarizer based on cross-shaped slot for high-power microwave applications.

A compact high-power waveguide circular polarizer working at the C-band is presented in this paper. By introducing a split-ring slot and an orthogonally crossed rectangular slot into a circular waveguide, high transmission efficiency and 90° phase difference of two linearly polarized orthogonal TE11 modes are achieved by using the polarizer within a half wavelength. In the meantime, the power handling capacity of the designed polarizer is expected to be over 120 MW, which can be applied in the high-power microwave region. The designed circular polarizer is fabricated and measured by the cold test; the results of experiments and simulations agree well with each other. It is shown in the experiments that the axial ratio is less than 0.9 dB, the voltage standing-wave ratio is less than 1.2, and the conversion efficiency is over -0.15 dB at 4.2-4.4 GHz.

An aperture coupled microstrip antenna array for high power microwave application.

A three-layer aperture coupled microstrip antenna array (ACMA) is designed and fabricated for wideband high-power microwave (HPM) application, which has not been reported in the field of HPM. In this paper, the proposed antenna array overcomes the disadvantage of low power capacity of traditional microstrip antenna arrays. Moreover, based on the H-shaped aperture coupled structure, it enhances the relative bandwidth up to more than 50%. Compared with traditional HPM antennas, it has advantages of being low-profile (less than 0.2λ), wideband, lightweight, and easy to manufacture. The proposed antenna array consists of 60 elements; each element has four aperture coupled patch antennas fed by a four-way microstrip line power divider. In order to realize the modular design, the antenna array is divided into 10 identical modules; benefiting from this design, machining and assembling become easier. Additionally, cold tests and high-power tests are carried out, and the experimental results show that the ACMA achieves a relative bandwidth of 51.2% for voltage standing-wave ratio < 2 from 1.52 to 2.57 GHz. Consistent with simulation results, the measured gain is more than 28.8 dB in the whole bandwidth and it reaches a maximum of 32.1 dB. Finally, the high-power tests show that the power capacity of the proposed ACMA is greater than 140 MW, which proves the feasibility of the design in wideband HPM application.

Distributed fibre optofluidic laser for chip-scale arrayed biochemical sensing.

Optofluidic lasers (OFLs) are an emerging technological platform for biochemical sensing, and their good performance especially high sensitivity has been demonstrated. However, high-throughput detection with an OFL remains a major challenge due to the lack of reproducible optical microcavities. Here, we introduce the concept of a distributed fibre optofluidic laser (DFOFL) and demonstrate its potential for high-throughput sensing applications. Due to the precise fibre geometry control via fibre drawing, a series of identical optical microcavities uniformly distributed along a hollow optical fibre (HOF) can be achieved to obtain a one-dimensional (1D) DFOFL. An enzymatic reaction catalysed by horseradish peroxidase (HRP) can be monitored over time, and the HRP concentration is detected by DFOFL-based arrayed colorimetric detection. Experimentally, five-channel detection in parallel with imaging has been demonstrated. Theoretically, spatial multiplexing of hundreds of channels is achievable with DFOFL-based detection. The DFOFL wavelength is tuned over hundreds of nanometers by optimizing the dye concentration or reconfiguring the liquid gain materials. Extending this concept to a two-dimensional (2D) chip through wavelength multiplexing can further enhance its multi-functionality, including multi-sample detection and spectral analysis. This work opens the door to high-throughput biochemical sensing.

Iron Robustly Stimulates Simultaneous Nitrification and Denitrification Under Aerobic Conditions.

Simultaneous nitrification and denitrification (SND) is a promising single-reactor biological nitrogen-removal method. Activated sludge with and without iron scrap supplementation (Sludge-Fe and Sludge-C, respectively) was acclimated under aerobic condition. The total nitrogen (TN) content of Sludge-Fe substantially decreased from 25.0 ± 1.0 to 11.2 ± 0.4 mg/L, but Sludge-C did not show the TN-removal capacity. Further investigations excluded a chemical reduction of NO3--N by iron and a decrease of NH4+-N by microbial assimilation, and the contribution of SND was verified. Moreover, the amount of aerobic denitrifiers, such as bacteria belonging to the genera Thauera, Thermomonas, Rhodobacter, and Hyphomicrobium, was considerably enhanced, as observed through Miseq Illumina sequencing method. The activities of the key enzymes ammonia monooxygenase (AMO) and nitrite oxidoreductase (NXR), which are associated with nitrification, and periplasmic nitrate reductase (NAP) and nitrite reductase (NIR), which are related to denitrification, in Sludge-Fe were 1.23-, 1.53-, 3.60-, and 1.55-fold higher than those in Sludge-C, respectively. In Sludge-Fe, the quantity of the functional gene NapA encoding enzyme NAP, which is essential for aerobic denitrification, was significantly promoted. The findings indicate that SND is the primary mechanism underlying the removal of TN and that iron scrap can robustly stimulate SND under aerobic environment.