Carrier-free immobilized enzymatic reactor based on CipA-fused carbonyl reductase for efficient synthesis of chiral alcohol with cofactor self-sufficiency.

In this study, based on the self-assembly strategy, we fused CipA with carbonyl reductase LXCARS154Y derived from Leifsonia xyli by gene coding, and successfully performed the carrier-free immobilization of LXCARS154Y. The immobilized enzyme was then characterized using scanning electron microscope (SEM), dynamic light scattering (DLS) and fourier transform infrared spectroscopy (FTIR). Compared with the free enzyme, the immobilized LXCARS154Y exhibited a 2.3-fold improvement in the catalytic efficiency kcat/km for the synthesis of a chiral pharmaceutical intermediate (R)-3,5-bis(trifluoromethyl)phenyl ethanol ((R)-BTPE) by reducing 3,5-bis(trifluoromethyl)acetophenone (BTAP). Moreover, the immobilized enzyme showed the enhanced stability while maintaining over 61 % relative activity after 18 cycles of batch reaction. Further, when CipA-fused carbonyl reductase was employed for (R)-BTPE production in a continuous flow reaction, almost complete yield (97.0 %) was achieved within 7 h at 2 M (512.3 g/L) of BTAP concentration, with a space-time yield of 1717.1 g·L-1·d-1. Notably, we observed the retention of cofactor NADH by CipA-based enzyme aggregates, resulting in a higher total turnover number (TTN) of 4815 to facilitate this bioreductive process. This research developed a concise strategy for efficient preparation of chiral intermediate with cofactor self-sufficiency via continuous flow biocatalysis, and the relevant mechanism was also explored.

Self-Powered and Self-Recovered Mechanoluminescent Electronic Skins for Detecting and Distinguishing Diverse External Stimuli.

The concept of simulating external mechanical stimuli to generate luminescence has been a long-standing aspiration in real-time dynamic visualization. However, creating self-power and self-restoring mechanoluminescent electronic skins for artificial sensors poses significant challenges. In this study, we introduce a cutting-edge triboelectric-mechanoluminescent electronic skin (TMES) that exhibits a remarkable response to multiple external stimuli. This advancement is achieved by integrating a mechanoluminescent intermediate layer within a triboelectric nanogenerator (TENG). When pressure is applied to TMES, the maximum detection voltage can reach hundreds of volts and the maximum correlation sensitivity is 11.76 V/N. Moreover, we incorporate luminescence materials into mechanoluminescence layer, and the maximum absolute sensitivity SR can reach 1.41%. The device can not only distinguish between external stimuli such as pressing and bending but also continuously track external mechanical stimuli. A 4 × 4 matrix and motion prediction of 8 different postures were established to further demonstrate the significant advantages of the developed device in spatial detection. The versatility and performance of the TMES hint at its vast potential in areas such as human-computer interaction and wearable electronics, paving the way for more intuitive and dynamic technological interfaces.

Multi-Mode Luminescence in Smart Near-Infrared Cr3+/Pr3+ Codoped SrGa12O19 Phosphors Induced by Three Distinct Excitation Mechanisms.

Near-infrared (NIR) phosphors have emerged as novel luminescent materials across various fields due to their unique advantages of high penetration and invisibility. However, there is currently a lack of intelligent NIR phosphors that can achieve multimode stimuli responsive for sensing applications. In this study, we employed a high-temperature solid-phase reaction to incorporate Pr3+ into Cr3+-doped gallate magnetite SrGa12O19 phosphor, yielding a multimode luminescent intelligent NIR phosphor. Also, due to the inherent cation vacancies and defects in the matrix, the material not only exhibits brighter photoluminescence but also exhibits distinct NIR mechanoluminescence at a lower load. Notably, Pr3+-doped SrGa12O19:Cr3+ also demonstrates extended persistent luminescence and thermoluminescence effects. Finally, we combined the phosphor with the blue LED chip to develop a new multifunctional NIR pc-LED. Leveraging NIR's unique penetrating ability, it can persist in biological tissues for prolonged periods, enabling optical inspection and offering a novel approach to password protection for anticounterfeiting measures. This intelligent NIR phosphor solution significantly expands the application potential of NIR light in food quality assessment and analysis.

Analysis and Comparison of New-Born Calf Standing and Lying Time Based on Deep Learning.

Standing and lying are the fundamental behaviours of quadrupedal animals, and the ratio of their durations is a significant indicator of calf health. In this study, we proposed a computer vision method for non-invasively monitoring of calves' behaviours. Cameras were deployed at four viewpoints to monitor six calves on six consecutive days. YOLOv8n was trained to detect standing and lying calves. Daily behavioural budget was then summarised and analysed based on automatic inference on untrained data. The results show a mean average precision of 0.995 and an average inference speed of 333 frames per second. The maximum error in the estimated daily standing and lying time for a total of 8 calf-days is less than 14 min. Calves with diarrhoea had about 2 h more daily lying time (p < 0.002), 2.65 more daily lying bouts (p < 0.049), and 4.3 min less daily lying bout duration (p = 0.5) compared to healthy calves. The proposed method can help in understanding calves' health status based on automatically measured standing and lying time, thereby improving their welfare and management on the farm.

Tri-enzyme fusion of tryptophan halogenase achieves a concise strategy for coenzyme self-sufficiency and the continuous halogenation of L-tryptophan.

The halogenase-based catalysis is one of the most environmentally friendly methods for the synthesis of halogenated products, among which flavin-dependent halogenases (FDHs) have attracted great interest as one of the most promising biocatalysts due to the remarkable site-selectivity and wide substrate range. However, the complexity of constructing the NAD+-NADH-FAD-FADH2 bicoenzyme cycle system has affected the engineering applications of FDHs. In this work, a coenzyme self-sufficient tri-enzyme fusion was constructed and successfully applied to the continuous halogenation of L-tryptophan. SpFDH was firstly identified derived from Streptomyces pratensis, a highly selective halogenase capable of generating 6-chloro-tryptophan from tryptophan. Then, using gene fusion technology, SpFDH was fused with glucose dehydrogenase (GDH) and flavin reductase (FR) to form a tri-enzyme fusion, which increased the yield by 1.46-fold and making the coenzymes self-sufficient. For more efficient halogenation of L-tryptophan, a continuous halogenation bioprocess of L-tryptophan was developed by immobilizing the tri-enzyme fusion and attaching it to a continuous catalytic device, which resulted in a reaction yield of 97.6% after 12 h reaction. An FDH from S. pratensis was successfully applied in the halogenation and our study provides a concise strategy for the preparation of halogenated tryptophan mediated by multienzyme cascade catalysis.

Preparation of Co-Ni-Ce/TiC alloy coatings by double-pulse under a sulfamic acid system and a process mechanism study.

To enhance the protective ability of copper crystallizers and extend their service life, this study explores the use of double pulse co-deposition under a sulfamic acid system to create protective coatings such as Co-Ni. The hardness test and friction wear analysis compare Co-Ni, Co-Ni-Ce, and Co-Ni-Ce/TiC coatings, revealing that the Co-Ni-Ce/TiC coating exhibits the most outstanding protective performance. SEM and XRD techniques are employed to characterize the three protective coatings, demonstrating that the incorporation of rare-earth cerium and nanoparticles improves the coating morphology and modifies their crystalline phase structure. Furthermore, cyclic voltammetry tests on the plating solutions of the three protective coatings indicate that the addition of Ce3+ and nanoparticles influences the deposition potentials. The deposition of Co2+ and Ni2+ follows a two-step, two-electron process, while the deposition of Ce3+ follows a one-step, three-electron process. It is observed that the deposition of all three ions is irreversible. To gain further insights into the nucleation mechanism of Ce3+, a chronoamperometry test is conducted, revealing that the nucleation of Ce3+ is a transient process controlled by diffusion.

Simcryocluster: a semantic similarity clustering method of cryo-EM images by adopting contrastive learning.

BACKGROUND: Cryo-electron microscopy (Cryo-EM) plays an increasingly important role in the determination of the three-dimensional (3D) structure of macromolecules. In order to achieve 3D reconstruction results close to atomic resolution, 2D single-particle image classification is not only conducive to single-particle selection, but also a key step that affects 3D reconstruction. The main task is to cluster and align 2D single-grain images into non-heterogeneous groups to obtain sharper single-grain images by averaging calculations. The main difficulties are that the cryo-EM single-particle image has a low signal-to-noise ratio (SNR), cannot manually label the data, and the projection direction is random and the distribution is unknown. Therefore, in the low SNR scenario, how to obtain the characteristic information of the effective particles, improve the clustering accuracy, and thus improve the reconstruction accuracy, is a key problem in the 2D image analysis of single particles of cryo-EM. RESULTS: Aiming at the above problems, we propose a learnable deep clustering method and a fast alignment weighted averaging method based on frequency domain space to effectively improve the class averaging results and improve the reconstruction accuracy. In particular, it is very prominent in the feature extraction and dimensionality reduction module. Compared with the classification method based on Bayesian and great likelihood, a large amount of single particle data is required to estimate the relative angle orientation of macromolecular single particles in the 3D structure, and we propose that the clustering method shows good results. CONCLUSIONS: SimcryoCluster can use the contrastive learning method to perform well in the unlabeled high-noise cryo-EM single particle image classification task, making it an important tool for cryo-EM protein structure determination.

Engineered the Active Site of ω-Transaminase for Enhanced Asymmetric Synthesis Towards (S)-1-[4-(Trifluoromethyl)phenyl]ethylamine.

ω-Transaminase (ω-TA) is a promising biocatalyst for the synthesis of chiral amines. In this study, a ω-TA derived from Vitreoscilla stercoraria DSM 513 (VsTA) was heterologous expressed in recombinant E. coli cells and applied to reduce 4'-(trifluoromethyl)acetophenone (TAP) to (S)-1-[4-(trifluoromethyl)phenyl]ethylamine ((S)-TPE), a pharmaceutical intermediate of chiral amine. Aimed to a more efficient synthesis of (S)-TPE, VsTA was further engineered via a semi-rational strategy. Compared to wild-type VsTA, the obtained R411A variant exhibited 2.39 times higher activity towards TAP and enhanced catalytic activities towards other prochiral aromatic ketones. Additionally, better thermal stability for R411A variant was observed with 25.4% and 16.3% increase in half-life at 30 °C and 40 °C, respectively. Structure-guided analysis revealed that the activity improvement of R411A variant was attributed to the introduction of residue A411, which is responsible for the increase in the hydrophobicity of substrate tunnel and the alleviation of steric hindrance, thereby facilitating the accessibility of hydrophobic substrate TAP to the active center of VsTA. This study provides an efficient strategy for the engineering of ω-TA based on semi-rational approach and has the potential for the molecular modification of other biocatalysts.

Parenthood, spatial temporal environmental exposure, and leisure-time physical activity participation: Evidence from a micro-timescale retrospective longitudinal study.

Parents with dependent children are at a high risk of physical inactivity. While previous studies have mostly focused on how parents' time constraints and changing social network may inhibit leisure time physical activity (LTPA) over the long-term, less is known about the integrated effects of parenting and spatial-temporal environmental exposure on the execution of LTPA during certain episodes of a day. By adopting an integrated social-spatiotemporal-environmental model (ST-ISEM) based on micro-timescale retrospective longitudinal analysis, we examine the association between LTPA participation and spatial-temporal environmental exposure at a micro-timescale, i.e., at the episode-level in working adults' workday, and specifically how parenting integrated with spatial-temporal environmental exposure can jointly influence episode-level LTPA participation. Using data from the day reconstruction method from 701 individuals in Shenzhen, China, we find that parenting may affect the participation of LTPA on workdays not only by shaping temporal environmental factors (time constraint path and social network path), but also by interacting with built environmental exposures (spatial path), both at the episode-level. This study contributes to the theorizing of an integrated social-environmental model for health and wellbeing by extending the ISEM from the life span to the micro-timescale and also by highlighting the importance of temporality in environmental exposure and health studies. It also contributes to the spatial temporal behavioral perspective of time geography literature by clarifying multiple pathways through which social and spatiotemporal environmental factors could interact and jointly affect health behaviors at a micro-timescale. This study contributes to the literature on parenting and LTPA decline by enriching and deepening the understanding of the time constraint and social network pathways through which parenting leads to LTPA change at the micro-timescale. While time constraints may decrease parents' LTPA at long-term, increasing physical activities related to childcare after work may strongly obstruct moderate-to-vigorous LTPA at a micro-timescale. This study also identifies a spatial pathway by which parenting hinders LTPA due to changing understanding and usage of urban spaces. This pathway warrants attention from social epidemiologists, health geographers, and urban planners since existing interventions promoting physical activity in urban spaces may be ineffective for parents.

Repair of soft magnetic properties of wasted silicon steel and Co7Fe3 alloy deposition mechanism.

In order to repair the soft magnetic properties of wasted silicon steel, a theoretical process of co-depositing Co-Fe soft magnetic alloy on the surface of wasted silicon steel is proposed. The results show that the co-deposited Co-Fe alloy coatings can serve to repair the soft magnetic properties of wasted silicon as detected by the vibrating sample magnetometer, and the alloy coatings with Co7Fe3 as the main phase structure can provide surface protection for silicon steel. Subsequently, the mechanism of co-deposited Co-Fe alloys was investigated, and it was concluded that Co2+ and Fe2+ undergo a one-step two-electron co-deposition reaction, as studied using cyclic voltammetry. The chronoamperometric analysis and its fitting results indicated that the deposition of Co2+ and Fe2+ was a diffusion-controlled transient nucleation process, and the AC impedance indicated that higher voltages were favorable for the deposition of Co-Fe alloys but were accompanied by hydrogen precipitation reactions.

Efficient asymmetric synthesis of ethyl (R)-3-hydroxybutyrate by recombinant Escherichia coli cells under high substrate loading using eco-friendly ionic liquids as cosolvent.

Ionic liquids (ILs) which synthesized from bio-renewable materials have recently attracted much attention for their applications in biocatalysis. Ethyl (R)-3-hydroxybutyrate ((R)-EHB) as a versatile chiral intermediate is of great interest in pharmaceutical synthesis. This study focuses on evaluating the performances of choline chloride (ChCl)-based and tetramethylammonium (TMA)-based neoteric ILs in the efficient synthesis of (R)-EHB via the bioreduction of ethyl acetoacetate (EAA) at high substrate loading by recombinant Escherichia coli cells. It was found that choline chloride/glutathione (ChCl/GSH, molar ratio 1:1) and tetramethylammonium/cysteine ([TMA][Cys], molar ratio 1:1) as eco-friendly ILs not only enhanced the solubility of water-insoluble EAA in the aqueous buffer system, but also appropriately improved the membrane permeability of recombinant E. coli cells, thus boosting catalytic reduction efficiency of EAA to (R)-EHB. In the developed ChCl/GSH- or [TMA][Cys]-buffer systems, the space-time yields of (R)-EHB achieved 754.9 g/L/d and 726.3 g/L/d, respectively, which are much higher than neat aqueous buffer system (537.2 g/L/d space-time yield). Meanwhile, positive results have also been demonstrated in the bioreduction of other prochiral ketones in the established IL-buffer systems. This work exhibits an efficient bioprocess for (R)-EHB synthesis under 325 g/L (2.5 M) substrate loading, and provides promising ChCl/GSH- and [TMA][Cys]-buffer systems employed in the biocatalysis for hydrophobic substrate.

Enhanced permeate flux by air micro-nano bubbles via reducing apparent viscosity during ultrafiltration process.

Micro-nano bubbles (MNBs) play important roles in the reduction of membrane fouling during membrane separation; however, such improvements are always attributed to the reduced concentration polarization on the surface of membranes and little attention has been paid on the variations of physicochemical properties of the feed caused by MNBs. In this study, the separation efficiencies of the feed containing humic acid (HA), bovine serum albumin (BSA), sodium alginate (SA) or dyes can be improved by MNBs during ultrafiltration, and the normalized fluxes can be maximally increased to 139% and 127% in the dead-end and cross-flow modes, respectively in the treatment of HA solution. We further reveal that the decreased apparent viscosity of the feed in the presence of MNBs is the key factor that enhances the normalized flux during ultrafiltration. This study gives new insight on the importance of MNBs in membrane separation and provides valuable clues for other chemical processes.

Effect of Polyethylene Glycol on Preparation of Magnesium Hydroxide by Electrodeposition.

The current research focuses on the mechanism of the surfactant polyethylene glycol (PEG) in the preparation of magnesium hydroxide by electrolysis of a salt lake bischite aqueous solution. The samples were analyzed by a scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR) and laser particle size analyzer. The characterization results show that PEG plays an important role in adjusting the growth mode and morphology of Mg(OH)2 crystals. The ether group of the PEG molecular chain and the hydroxyl group of Mg(OH)2 can be combined by a hydrogen bond, which provides a "template" for the growth of Mg(OH)2. At the same time, the difference in growth mode and morphology will also affect the economic performance of electrolytic reactions. When the PEG content reaches 0.4 g/L, the particle size of the product is uniform, which can well reduce the polarization of the electrode plate. The cell potential of electrolytic reaction is small, and the economic benefit is high. When the content of PEG is low, it has a low impact on the product and the economic benefits of electrolytic reaction. When the PEG content is higher than 0.4 g/L, the electrode reaction is hindered, resulting in an increase in cell potential.

Effect of highly efficient substrate modifier, super-absorbent polymer, on the performance of the green roof.

Green roofs are commonly used in sponge city construction. However, the limitations of substrate thickness and strong sunlight have caused water retention to become the primary problem in the promotion of this technology. Super-absorbent polymer (SAP) is a material with excellent water absorption capacity that is expected to improve the substrate to solve the problem of the insufficient water storage capacity of green roofs. In this study, the basic performances of two types of SAPs, namely polyacrylate sylvite and acrylic acid-attapulgite hybrid (P-SAP and A-SAP, respectively), were evaluated on a bench-scale. The results showed that both SAPs had good water absorption, reusability, and fertilizer protection ability. These SAPs could maintain high water absorption within a certain range of salinity, pH, and temperature. Although water absorption of P-SAP was higher than that of A-SAP, the latter showed a significant advantage in substrate modification. After adding A-SAP (application rate: 0.6%, particle size: 12 mesh), the water storage capacity of the substrate was significantly improved, with an increase in the saturation moisture content of 23.8% and a decrease in the infiltration rate of 48.5%. A simulator of green roof was constructed with A-SAP under optimal conditions. The enhancement of the water retention capacity increased the drought resistance of the plants, which improved their growth; in particular, the fresh weight was 98% higher than that of the control group. A-SAP increased the rate of building up the lawn by 25%. The average soil moisture of the A-SAP group was 63.3%, which was 10.0% higher than that of the control group. An increase of more than 26% in the runoff control capacity was found in the green roof with A-SAP. Overall, our study indicates that A-SAP is a practical and efficient modifier for green roofs.

[Clinical efficacy of Longjintonglin Capsules on chronic prostatitis with damp-heat stasis syndrome Re-evaluation based on multicenter real-world study].

OBJECTIVE: To re-evaluate the clinical efficacy of Longjintonglin Capsules (LJTL) in the treatment of chronic prostatitis with damp-heat stasis syndrome. METHODS: This multicenter real-world study included 1 352 cases of chronic prostatitis with damp-heat and stagnation syndrome treated with LJTL (3 capsules once, tid, 30 minutes after meals, for 2 four-week courses) in addition to routine treatment. Before and after treatment, we analyzed the NIH-CPSI scores, the scores of Chinese medicine symptom quantitative classification and changes in individual symptom scores, and observed adverse reactions to medication. RESULTS: The total effectiveness rate of LJTL was 93.64%. Compared with the baseline, the NIH-CPSI scores were significantly decreased after treatment (ï¼»24.27 ± 6.04ï¼½ vs ï¼»8.17 ± 4.21ï¼½, P < 0.05), and so were the scores on the pain symptoms (ï¼»9.63 ± 3.65ï¼½ vs ï¼»3.02 ± 2.23ï¼½, P < 0.05), voiding symptoms (ï¼»5.65 ± 2.15ï¼½ vs ï¼»1.62 ± 1.36) and quality of life (ï¼»8.96 ± 2.32ï¼½ vs ï¼»3.16 ± 1.89ï¼½, P < 0.05). The effectiveness rate of LJTL was 95.9% on the Chinese medicine symptom frequent urination, 90.4% on painful urination, and 91.4% scanty dark urine, with a total effectiveness rate of 82.4% － 95.9%, all with statistically significant difference in comparison with the baseline (P < 0.05). CONCLUSION: Longjintonglin Capsules combined with routine treatment can significantly improve the clinical symptoms of chronic prostatitis with damp-heat stasis syndrome, especially effective on the symptoms of frequent urination, painful urination and scanty dark urine. Besides, it recommendable for its antidepressant and antianxiety effects, and the effect of improving the quality of life of the chronic prostatitis patients with damp-heat stasis.

Extraction of Al from Coarse Al-Si Alloy by The Selective Liquation Method.

A selective liquation process to extract Al from a coarse Al-Si alloy, produced by carbothermal reduction, was investigated on the laboratory scale. The products obtained by selective liquation-vacuum distillation were analyzed by X-ray diffraction, inductively coupled plasma optical emission spectrometry and scanning electron microscopy. During the selective liquation process with the use of zinc as the solvent, the pure aluminum in the coarse Al-Si alloy dissolved in the zinc melt to form an α-solid solution with zinc, and most of the silicon and iron-rich phases and Al-Si-Fe intermetallics precipitated and grew into massive grains that entered into the slag and separated with the Zn-Al alloy melt. However, some fine silicon particles remained in the Zn-Al alloy. Thus, Al-Si alloys conforming to industrial application standards were obtained when the Zn-Al alloys were separated by a distillation process.

Textiles/Metal-Organic Frameworks Composites as Flexible Air Filters for Efficient Particulate Matter Removal.

The health-threatening air pollution, especially from particulate matter (PM), has triggered increasing demands for developing low-cost and long-service-life air-cleaning technologies. In the present contribution, a range of high-efficiency textiles/metal-organic framework (MOF) composites (MOFs@textiles) air filters with excellent washable reusability is presented. By processing MOFs onto textile substrates via an eco-friendly solvent-free method to enable the microporous feature and also strong PM adhesion, we develop flexible, highly effective air filters with >95.00% PM removal efficiency (e.g., MiL-53(Al)@Aramid, PM2.5: 95.30%, PM10: 96.11%) under harmful air quality conditions (average PM2.5 mass concentration > 280 µg m-3 and PM10 > 360 µg m-3). Therefore, these MOFs@textiles are promising composites for producing efficient and recyclable out-/indoor air purifiers.

Microdeletion at 8q24.13 rather than multistep microsatellite mutation resulting in the genetic inconsistency at the D8S1179 locus in a true trio.

When using microsatellite loci for DNA paternity testing, genetic inconsistencies sometimes occur in true trios and duos and may be erroneously attributed to germline mutations of microsatellite alleles. Here, we reported a typical case and discussed the issue of how to find out the cause of a genetic inconsistency. In our case, a genetic inconsistency in a true trio was observed at the D8S1179 locus, where the father has only allele 10 as compared to only allele 16 of his son. A set of tests were then performed. The results showed that the inconsistency was not result from the germline mutation of allele 10 to allele 16, or from the presence of null alleles due to primer binding site mutations, but from the microdeletion at 8q24.13, about 2.99 to 49.76 kb, detected in both the father and his son, which revealed by deletion mapping using short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs). In conclusion, genetic inconsistencies observed in true trios or duos cannot be rashly attributed to germline STR mutations, especially multistep mutations, in the absence of verification or specification; otherwise, the reliability of the genetic proofs established will be challenged.

A novel multiplex assay of SNP-STR markers for forensic purpose.

Like DIP-STR markers (deletion/insertion polymorphism-short tandem repeat combinations), SNP-STR markers (single nucleotide polymorphism-STR combinations) are also valuable in forensic DNA mixture analysis. In this study, eight SNP-STRs were selected, and a stable and sensitive multiplex polymerase chain reaction (PCR) assay was developed for amplifying these SNP-STRs and the Amelogenin gender marker according to the principle of amplification refractory mutation system (ARMS). This novel multiplex set allows detection of the minor DNA contributor in a DNA mixture of any gender and cellular origin with high resolution (beyond a DNA ratio of 1:20). In addition, SNP-STR haplotype frequencies were estimated based on a survey of 350 unrelated individuals from Chinese Han population, and the combined power of discrimination (PD) and power of exclusion (PE) of the eight SNP-STRs were calculated as 0.99999999965 and 0.9996, which were obviously higher than that of the eight STR loci: 0.9999999954 and 0.9989 respectively. The results indicated that the SNP-STR compound markers have higher application value in forensic identification compared to standard autosomal STRs, especially in the analysis of imbalanced DNA mixtures.

Health and economic benefits of building ventilation interventions for reducing indoor PM2.5 exposure from both indoor and outdoor origins in urban Beijing, China.

China is confronted with serious PM2.5 pollution, especially in the capital city of Beijing. Exposure to PM2.5 could lead to various negative health impacts including premature mortality. As people spend most of their time indoors, the indoor exposure to PM2.5 from both indoor and outdoor origins constitutes the majority of personal exposure to PM2.5 pollution. Different building interventions have been introduced to mitigate indoor PM2.5 exposure, but always at the cost of energy expenditure. In this study, the health and economic benefits of different ventilation intervention strategies for reducing indoor PM2.5 exposure are modeled using a representative urban residence in Beijing, with consideration of different indoor PM2.5 emission strengths and outdoor pollution. Our modeling results show that the increase of envelope air-tightness can achieve significant economic benefits when indoor PM2.5 emissions are absent; however, if an indoor PM2.5 source is present, the benefits only increase slightly in mechanically ventilated buildings, but may show negative benefit without mechanical ventilation. Installing mechanical ventilation in Beijing can achieve annual economic benefits ranging from 200yuan/capita to 800yuan/capita if indoor PM2.5 sources exist. If there is no indoor emission, the annual benefits above 200yuan/capita can be achieved only when the PM2.5 filtration efficiency is no <90% and the envelope air-tightness is above Chinese National Standard Level 7. Introducing mechanical ventilation with low PM2.5 filtration efficiency to current residences in urban Beijing will increase the indoor PM2.5 exposure and result in excess costs to the residents.