| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Wang, Yuan, et al.
(författare)
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Half-spectrum OFDM to quadruple the spectral efficiency of underwater wireless optical communication with digital power division multiplexing
- 2024
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Ingår i: Applied Optics. - : Optica Publishing Group. - 1559-128X .- 2155-3165. ; 63:9, s. 2352-2361
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Tidskriftsartikel (refereegranskat)abstract
- Improving the spectrum efficiency (SE) is an effective method to further enhance the data rate of bandwidthmultiplexing (NOFDM) with a compression factor of 0.5 can save half of the bandwidth without introducing any inter-carrier-interference (ICI) only if the total number of subcarriers is large enough, and we termed it as half-spectrum OFDM (HS-OFDM). To the best of our knowledge, this is the first reported work on a closed-form HS-OFDM signal in the discrete domain from the perspective of a correlation matrix. Due to the special mathematical property, no extra complex decoding algorithm is required at the HS-OFDM receiver, making it as simple as the conventional OFDM receiver. Compared with traditional OFDM, HS-OFDM can realize the same data rate, but with a larger signal-to-noise ratio (SNR) margin. To fully use the SNR resource of the communication system, we further propose a digital power division multiplexed HS-OFDM (DPDM-HS-OFDM) scheme to quadruple the SE of conventional OFDM for the bandwidth-starved UWOCs. The experimental results show that HS-OFDM can improve the receiver sensitivity by around 4 dB as opposed to conventional 4QAM-OFDM with the same data rate and SE. With the help of the DPDM-HS-OFDM scheme, the data rate of multi-user UWOC can reach up to 4.5 Gbps under the hard-decision forward error correction (HD-FEC) limit of a bit error rate (BER) of 3.8 x 10-3. Although there is some performance degradation in comparison with single-user HS-OFDM, the BER performance of multi-user DPDM-HS-OFDM is still superior to that of conventional single-user 4QAM-OFDM. Both single-user HS-OFDM and multi-user DPDM-HS-OFDM successfully achieve 2 Gbps/75 m data transmission, indicating that the DPDM-HS-OFDM scheme is of great importance in bandwidth-limited UWOC systems and has guiding significance to underwater wireless optical multiple access.
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| 3. |
- Wang, Yuan, et al.
(författare)
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Three Gossiping Protocols in Three-Dimensional Underwater Optical Cellular Network
- 2023
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Ingår i: 2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- In this paper, three different low-complexity sector-based Gossiping routing protocols, namely Gossiping with probabilistic selection (Gossiping-PS), Gossiping with visibility priority (Gossiping-VP), and Gossiping with energy priority (Gossiping-EP), are evaluated through the three-dimensional underwater optical cellular network (UOCN). Comprehensive performance comparisons are made among the above three routing protocols in terms of the average hop, end-to-end delay, network lifetime, packet-loss rate, and energy utilization. Numerical analysis shows that Gossiping-PS significantly outperforms the other two schemes, while Gossiping-Vpand Gossiping-EP behave even worse than the standard Gossiping routing protocol under some circumstances, which is owing to the fact that the Greedy algorithm makes the best choice for the current moment instead of taking the global optimality into consideration.
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| 4. |
- Zhang, Tianyi, et al.
(författare)
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19.02Gbps/25m Underwater Wireless Optical Communication Adopting Probabilistic Constellation Shaping QAM-DMT Transmission
- 2023
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Ingår i: 2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrated probabilistic constellation shaping quadrature amplitude modulation discrete multitone (PCS QAM-DMT) for 25-m underwater wireless optical communication (UWOC) system with a net data rate of 19.02Gbps. 28.1% capacity improvement is achieved in comparison with conventional bit-power loading DMT scheme. To the best of our knowledge, this is the highest net data rate ever reported for a single LD in current UWOC.
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| 5. |
- Chong, Hui, et al.
(författare)
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Organo-ptii complexes for potent photodynamic inactivation of multi-drug resistant bacteria and the influence of configuration
- 2024
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Ingår i: Advanced Science. - : John Wiley & Sons. - 2198-3844. ; 11:14
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Tidskriftsartikel (refereegranskat)abstract
- PtII based organometallic photosensitizers (PSs) have emerged as novel potent photodynamic inactivation (PDI) reagents through their enhanced intersystem crossing (ISC) processes. Currently, few PtII PSs have been investigated as antibacterial materials, with relatively poor performances reported and with structure-activity relationships not well described. Herein, a pair of configurational isomers are reported of Bis-BODIPY (4,4-difluoro-boradizaindacene) embedded PtII PSs. The cis-isomer (cis-BBP) displayed enhanced 1O2 generation and better bacterial membrane anchoring capability as compared to the trans-isomer (trans-BBP). The effective PDI concentrations (efficiency > 99.9%) for cis-BBP in Acinetobacter baumannii (multi-drug resistant (MDR)) and Staphylococcus aureus are 400 nM (12 J cm−2) and 100 nM (18 J cm−2), respectively; corresponding concentrations and light doses for trans-BBP in the two bacteria are 2.50 µM (30 J cm−2) and 1.50 µM (18 J cm−2), respectively. The 50% and 90% minimum inhibitory concentration (MIC50 and MIC90) ratio of trans-BBP to cis-BBP is 22.22 and 24.02 in A. baumannii (MDR); 21.29 and 22.36 in methicillin resistant S. aureus (MRSA), respectively. Furthermore, cis-BBP displays superior in vivo antibacterial performance, with acceptable dark and photoinduced cytotoxicity. These results demonstrate cis-BBP is a robust light-assisted antibacterial reagent at sub-micromolecular concentrations. More importantly, configuration of PtII PSs should be an important issue to be considered in further PDI reagents design.
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| 6. |
- Wang, Yuan, et al.
(författare)
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Spectrally Efficient Non-Orthogonal Discrete Multi-Tone Transmission for Underwater Wireless Optical Communication With Low-Complexity High Performance ICI Mitigation
- 2023
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 41:19, s. 6288-6299
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Tidskriftsartikel (refereegranskat)abstract
- In this article, a novel spectrally efficient non-orthogonal discrete multi-tone (NODMT) system is proposed for the bandwidth-starved underwater wireless optical communication (UWOC) to compensate for the insufficient bandwidth of components. Different from other non-orthogonal systems with complex-valued correlation matrices, the designed NODMT system has a real-valued correlation matrix, which is significant in reducing the complexity of decoders, e.g., the complexity of the proposed NODMT with iterative detection (ID) algorithm can be reduced by 50% as compared to the conventional non-orthogonal system with ID. However, in circumstances of higher spectrum efficiency (SE), the non-orthogonality is intensified and inter-carrier interference (ICI) becomes severer, leading to the sharp deterioration of ID decoding capability. The traditional sphere decoding (SD) algorithm cannot solve this issue because Cholesky decomposition only works with the positive definite matrix. Therefore, we propose a novel SD algorithm based on QR decomposition, named QRSD, which effectively compensates for the insufficient decoding capability of the ID algorithm in the case of higher SE. By combining ID and QRSD methods, over 40% complexity reduction and nearly identical BER performance with QRSD are achieved. Through a proof-of-concept UWOC experiment, a 3.31-Gbps NODMT transmission with up to 24.44% data rate promotion is demonstrated, and the feasibility/effectiveness of the proposed ID-QRSD algorithm in different turbidity water is verified. Moreover, we have experimentally realized 75-m/2.66-Gbps and 60-m/3.02-Gbps underwater transmission with 15% and 25% bandwidth savings, respectively. This UWOC system with high SE shows great potential in the bandwidth-limited UWOC and underwater internet of things (UIoT).
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| 7. |
- Chen, Ruilin, et al.
(författare)
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Experimental demonstration of real-time optical DFT-S DMT signal transmission for a blue-LED-based UWOC system using spatial diversity reception
- 2023
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Ingår i: Applied Optics. - : Optica Publishing Group. - 1559-128X .- 2155-3165. ; 62:3, s. 541-551
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Tidskriftsartikel (refereegranskat)abstract
- Underwater wireless optical communication (UWOC) has broad prospects in underwater real-time applications. We design and experimentally demonstrate a real-time discrete Fourier transform spread discrete multi-tone (DFT-S DMT) signal transmission based on a field programmable gate array for a blue-LED-based UWOC system with a data rate of up to 30 Mbps over a 15-m underwater channel. The architecture and usage of an on-chip resource as well as power consumption are analyzed and discussed. To reduce the impacts of multipath fading and received intensity fluctuation, spatial diversity reception is also introduced. Furthermore, the receiver sensitivity at a speci-fied bit error rate (BER) threshold and the quality of the images are evaluated using three types of Reed-Solomon (RS) codes. At the BER threshold of 10-4, over 2.8-dB receiver sensitivity improvement is obtained by the DFT-S DMT scheme with the RS (64, 56) code as compared to the uncoded one at the data rate of 30 Mbps. The perform-ance of BER, color difference, and structural similarity in the image transmission of DFT-S DMT is superior to that of the conventional hard clipping quadrature amplitude modulation DMT in a high-data-rate region because of the low peak-to-average-power ratio and ability to mitigate high-frequency fading in a band-limited UWOC system. With schemes of the RS code, DFT-S, and diversity reception, error-free transmission of images is achieved over a 15-m water channel. The proposed UWOC system has the advantages of low power consumption and porta-bility, which foresees a bright future in underwater applications over short to moderate distances.
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| 8. |
- Chen, Tianyi, et al.
(författare)
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Maternal exposure to PM2.5/BC during pregnancy predisposes children to allergic rhinitis which varies by regions and exclusive breastfeeding
- 2022
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 165
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIncreasing prevalence of childhood allergic rhinitis(AR) needs a deeper understanding on the potential adverse effects of early life exposure to air pollution.ObjectivesThe main aim was to evaluate the effects of maternal exposure to PM2.5 and chemical constituents during pregnancy on preschool children’s AR, and further to explore the modification effects of regions and exclusive breastfeeding.MethodsA multi-center population-based study was performed in 6 cities from 3 regions of China in 2011–2012. Maternal exposure to ambient PM2.5 and main chemical constituents(BC, OM, SO42−, NO3−, NH4+) during pregnancy was assessed and a longitudinal prospective analysis was applied on preschool children’s AR. The modification effects of regions and exclusive breastfeeding were investigated.ResultsA total of 8.8% and 9.8% of children reported doctor-diagnosed allergic rhinitis(DDAR) and current hay fever, respectively, and 48.6% had less than 6 months of exclusive breastfeeding. The means of PM2.5 during pregnancy were 52.7 μg/m3, 70.3 μg/m3 and 76.4 μg/m3 in the east, north and central south of China, respectively. Multilevel log-binomial model regression showed that each interquartile range(IQR) increase of PM2.5 during pregnancy was associated with an average increase in prevalence ratio (PR) of DDAR by 1.43(95% confidence interval(CI): 1.11, 1.84) and current hay fever by 1.79(95% CI: 1.26, 2.55), respectively. Among chemical constituents, black carbon (BC) had the strongest associations. Across 3 regions, the eastern cities had the highest associations, followed by those in the central south and the north. For those equal to or longer than 6 months of exclusive breastfeeding, the associations were significantly reduced.ConclusionsChildren in east of China had the highest risks of developing AR per unit increase of maternal exposure to PM2.5 during pregnancy, especially BC constituent. Remarkable decline was found in association with an increase in breastfeeding for ≥6 months, in particular in east of China.
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| 9. |
- Liu, Yang, et al.
(författare)
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MiR-378a suppresses tenogenic differentiation and tendon repair by targeting at TGF-β2
- 2019
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Ingår i: Stem Cell Research and Therapy. - : Springer Science and Business Media LLC. - 1757-6512. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Tendons are a crucial component of the musculoskeletal system and responsible for transmission forces derived from muscle to bone. Patients with tendon injuries are often observed with decreased collagen production and matrix degeneration, and healing of tendon injuries remains a challenge as a result of limited understanding of tendon biology. Recent studies highlight the contribution of miR-378a on the regulation gene expression during tendon differentiation. Methods: We examined the tendon microstructure and tendon repair with using miR-378a knock-in transgenic mice, and the tendon-derived stem cells were also isolated from transgenic mice to study their tenogenic differentiation ability. Meanwhile, the expression levels of tenogenic markers were also examined in mouse tendon-derived stem cells transfected with miR-378a mimics during tenogenic differentiation. With using online prediction software and luciferase reporter assay, the binding target of miR-378a was also studied. Results: Our results indicated miR-378a impairs tenogenic differentiation and tendon repair by inhibition collagen and extracellular matrix production both in vitro and in vivo. We also demonstrated that miR-378a exert its inhibitory role during tenogenic differentiation through binding at TGFβ2 by luciferase reporter assay and western blot. Conclusions: Our investigation suggests that miR-378a could be considered as a new potential biomarker for tendon injury diagnosis or drug target for a possible therapeutic approach in future clinical practice.
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| 10. |
- Shi, Haonan, et al.
(författare)
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Prevalence, risk factors, impact and management of pneumonia among preschool children in Chinese seven cities : a cross-sectional study with interrupted time series analysis
- 2023
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Ingår i: BMC Medicine. - : BioMed Central (BMC). - 1741-7015. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pneumonia is a common disease worldwide in preschool children. Despite its large population size, China has had no comprehensive study of the national prevalence, risk factors, and management of pneumonia among preschool children. We therefore investigated the prevalence of pneumonia among preschool children in Chinese seven representative cities, and explore the possible risk factors of pneumonia on children, with a view to calling the world's attention to childhood pneumonia to reduce the prevalence of childhood pneumonia.Methods: Two group samples of 63,663 and 52,812 preschool children were recruited from 2011 and 2019 surveys, respectively. Which were derived from the cross-sectional China, Children, Homes, Health (CCHH) study using a multi-stage stratified sampling method. This survey was conducted in kindergartens in seven representative cities. Exclusion criteria were younger than 2 years old or older than 8 years old, non-permanent population, basic information such as gender, date of birth and breast feeding is incomplete. Pneumonia was determined on the basis of parents reported history of clearly diagnosed by the physician. All participants were assessed with a standard questionnaire. Risk factors for pneumonia, and association between pneumonia and other respiratory diseases were examined by multivariable-adjusted analyses done in all participants for whom data on the variables of interest were available. Disease management was evaluated by the parents' reported history of physician diagnosis, longitudinal comparison of risk factors in 2011 and 2019.Results: In 2011 and 2019, 31,277 (16,152 boys and 15,125 girls) and 32,016 (16,621 boys and 15,395 girls) preschool children aged at 2-8 of permanent population completed the questionnaire, respectively, and were thus included in the final analysis. The findings showed that the age-adjusted prevalence of pneumonia in children was 32.7% in 2011 and 26.4% in 2019. In 2011, girls (odds ratio [OR] 0.91, 95%CI [confidence interval]0.87-0.96; p = 0.0002), rural (0.85, 0.73-0.99; p = 0.0387), duration of breastfeeding & GE; 6 months(0.83, 0.79-0.88; p < 0.0001), birth weight (g) & GE; 4000 (0.88, 0.80-0.97; p = 0.0125), frequency of putting bedding to sunshine (Often) (0.82, 0.71-0.94; p = 0.0049), cooking fuel type (electricity) (0.87, 0.80-0.94; p = 0.0005), indoor use air-conditioning (0.85, 0.80-0.90; p < 0.0001) were associated with a reduced risk of childhood pneumonia. Age (4-6) (1.11, 1.03-1.20; p = 0.0052), parental smoking (one) (1.12, 1.07-1.18; p < 0.0001), used antibiotics (2.71, 2.52-2.90; p < 0.0001), history of parental allergy (one and two) (1.21, 1.12-1.32; p < 0.0001 and 1.33, 1.04-1.69; p = 0.0203), indoor dampness (1.24, 1.15-1.33; p < 0.0001), home interior decoration (1.11, 1.04-1.19; p = 0.0013), Wall painting materials (Paint) (1.16, 1.04-1.29; p = 0.0084), flooring materials (Laminate / Composite wood) (1.08, 1.02-1.16; p = 0.0126), indoor heating mode(Central heating)(1.18, 1.07-1.30, p = 0.0090), asthma (2.38, 2.17-2.61; p < 0.0001), allergic rhinitis (1.36, 1.25-1.47; p < 0.0001), wheezing (1.64, 1.55-1.74; p < 0.0001) were associated with an elevated risk of childhood pneumonia; pneumonia was associated with an elevated risk of childhood asthma (2.53, 2.31-2.78; p < 0.0001), allergic rhinitis (1.41, 1.29-1.53; p < 0.0001) and wheezing (1.64, 1.55-1.74; p < 0.0001). In 2019, girls (0.92, 0. 87-0.97; p = 0.0019), duration of breastfeeding & GE; 6 months (0.92, 0.87-0.97; p = 0.0031), used antibiotics (0.22, 0.21-0.24; p < 0.0001), cooking fuel type (Other) (0.40, 0.23-0.63; p = 0.0003), indoor use air-conditioning (0.89, 0.83-0.95; p = 0.0009) were associated with a reduced risk of childhood pneumonia. Urbanisation (Suburb) (1.10, 1.02-1.18; p = 0.0093), premature birth (1.29, 1.08-1.55; p = 0.0051), birth weight (g) < 2500 (1.17, 1.02-1.35; p = 0.0284), parental smoking (1.30, 1.23-1.38; p < 0.0001), history of parental asthma (One) (1.23, 1.03-1.46; p = 0.0202), history of parental allergy (one and two) (1.20, 1.13-1.27; p < 0.0001 and 1.22, 1.08-1.37; p = 0.0014), cooking fuel type (Coal) (1.58, 1.02-2.52; p = 0.0356), indoor dampness (1.16, 1.08-1.24; p < 0.0001), asthma (1.88, 1.64-2.15; p < 0.0001), allergic rhinitis (1.57, 1.45-1.69; p < 0.0001), wheezing (2.43, 2.20-2.68; p < 0.0001) were associated with an elevated risk of childhood pneumonia; pneumonia was associated with an elevated risk of childhood asthma (1.96, 1.72-2.25; p < 0.0001), allergic rhinitis (1.60, 1.48-1.73; p < 0.0001) and wheezing (2.49, 2.25-2.75; p < 0.0001).Conclusions: Pneumonia is prevalent among preschool children in China, and it affects other childhood respiratory diseases. Although the prevalence of pneumonia in Chinese children shows a decreasing trend in 2019 compared to 2011, a well-established management system is still needed to further reduce the prevalence of pneumonia and reduce the burden of disease in children.
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| 11. |
- Tian, Jiahan, et al.
(författare)
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Wide-field-of-view auto-coupling optical antenna system for high-speed bidirectional optical wireless communications in C band
- 2023
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Ingår i: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 31:20, s. 33435-33448
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Tidskriftsartikel (refereegranskat)abstract
- Due to a great many superior features of infrared light communication (ILC), like high capacity and strong privacy, ILC is considered a potential candidate for serving the high demands of beyond fifth-generation/sixth-generation (B5G/6 G) communication systems. However, the terminal's limited field-of-view (FOV) induces great difficulty in establishing line-of-sight (LoS) link between the transceiver and the terminal. In this paper, we propose a wide-FOV auto-coupling optical antenna system that utilizes a wide-FOV telecentric lens to collect incident infrared beams and automatically couple them into a specific single-mode-fiber (SMF) channel of fiber array and optical switch. The performance of this optical antenna system is assessed through simulation and manual alignment operation, and validated by automatic alignment results. A coupling loss of less than 10.6 dB within a FOV of 100(degrees )for both downstream and upstream beams in C band is demonstrated by the designed system. Furthermore, we establish a bidirectional optical wireless communications (OWC) system employing this antenna and a fiber-type modulating retro-reflector (MRR) system in the terminal. Both 10-Gbps on-off keying (OOK) downstream and upstream transmissions are successfully realized with the FOV of up to 100(degrees) in C band where the measured bit-error-rate (BER) is lower than 3.8 x 10-3. To the best of our knowledge, this is a brand-new auto-coupling optical antenna system with the largest FOV in ILC automatic alignment works in terminals that have ever been reported.
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| 12. |
- Tian, Jiahan, et al.
(författare)
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Wide-Field-of-View Modulating Retro-Reflector System Based on a Telecentric Lens for High-Speed Free-Space Optical Communication
- 2023
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Ingår i: IEEE Photonics Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0655. ; 15:5
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Tidskriftsartikel (refereegranskat)abstract
- Modulating retro-reflector (MRR) free-space optical (FSO) communication technology presents a bright future for realizing the small size, weight, and power (SWaP) design of one end of the optical link, facilitating the further application of the FSO communication to the small platforms. However, the limited field-of-view (FOV) of MRR impedes its wide employment. In this article, a novel wide-FOV MRR using an image space telecentric lens is proposed and a bidirectional FSO communication system is experimentally demonstrated using this MRR with a single light source. The performance of the telecentric lens between the transceiver and terminal is assessed by simulation and also validated by experimental results, with a coupling loss less than 9.1 dB within a FOV of 110 degrees. Both 10-Gbit/s on-off keying (OOK) downstream and upstream signals for free space communication at different incident angles are successfully realized using this designed wide-FOV MRR. The experimental results validate the proposed MRR has a FOV of up to 110 degrees where the measured bit error rate (BER) is lower than 3.8 x 10-3 for both downstream and upstream signals. To the best of our knowledge, this is the largest FOV ever reported for MRRs in high-speed bidirectional FSO communication systems.
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| 13. |
- Yang, Liu, et al.
(författare)
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Prenatal and postnatal early life exposure to greenness and particulate matter of different size fractions in relation to childhood rhinitis : A multi-center study in China
- 2024
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 938
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Tidskriftsartikel (refereegranskat)abstract
- The impact of early life exposure to residential greenness on childhood rhinitis and its interaction with particulate matter (PM) of different size fractions remain inconsistent. Herein, we recruited 40,486 preschool children from randomly selected daycare centers in 7 cities in China from 2019 to 2020, and estimated exposure to residential greenness by the normalized difference vegetation index (NDVI) with a 500 m buffer. Exposure to ambient PM (PM1, PM2.5, and PM10) was evaluated using a satellite-based prediction model (daily, at a resolution of 1 km × 1 km). By mixed-effect logistic regression, NDVI values during pregnancy, in the first (0–1 year old) and the second (1–2 years old) year of life were negatively associated with lifetime rhinitis (LR) and current rhinitis (CR) (P < 0.001). PM in the same time windows was associated with increased risks of LR and CR in children, with smaller size fraction of PM showing greater associations. The negative associations between prenatal and postnatal NDVI and LR and CR in preschool children remained robust after adjusting for concomitant exposure to PM, whereas the associations of postnatal NDVI and rhinitis showed significant interactions with PM. At lower levels of PM, postnatal NDVI remained negatively associated with rhinitis and was partly mediated by PM (10.0–40.9 %), while at higher levels of PM, the negative associations disappeared or even turned positive. The cut-off levels of PM were identified for each size fraction of PM. In conclusion, prenatal exposure to greenness had robust impacts in lowering the risk of childhood rhinitis, while postnatal exposure to greenness depended on the co-exposure levels to PM. This study revealed the complex interplay of greenness and PM on rhinitis in children. The exposure time window in prenatal or postnatal period and postnatal concomitant PM levels played important roles in influencing the associations between greenness, PM and rhinitis.
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| 14. |
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| 15. |
- Yuan, Jun, et al.
(författare)
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Enabling low voltage losses and high photocurrent in fullerene-free organic photovoltaics
- 2019
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Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Despite significant development recently, improving the power conversion efficiency of organic photovoltaics (OPVs) is still an ongoing challenge to overcome. One of the prerequisites to achieving this goal is to enable efficient charge separation and small voltage losses at the same time. In this work, a facile synthetic strategy is reported, where optoelectronic properties are delicately tuned by the introduction of electron-deficient-core-based fused structure into non-fullerene acceptors. Both devices exhibited a low voltage loss of 0.57 V and high short-circuit current density of 22.0 mA cm(-2), resulting in high power conversion efficiencies of over 13.4%. These unconventional electron-deficient-core-based non-fullerene acceptors with near-infrared absorption lead to low non-radiative recombination losses in the resulting organic photovoltaics, contributing to a certified high power conversion efficiency of 12.6%.
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| 16. |
- Chen, Min, et al.
(författare)
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Highly stable and efficient all-inorganic lead-free perovskite solar cells with native-oxide passivation
- 2019
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- There has been an urgent need to eliminate toxic lead from the prevailing halide perovskite solar cells (PSCs), but the current lead-free PSCs are still plagued with the critical issues of low efficiency and poor stability. This is primarily due to their inadequate photovoltaic properties and chemical stability. Herein we demonstrate the use of the lead-free, all-inorganic cesium tin-germanium triiodide (CsSn(0.5)Ge(0.5)l(3)) solid-solution perovskite as the light absorber in PSCs, delivering promising efficiency of up to 7.11%. More importantly, these PSCs show very high stability, with less than 10% decay in efficiency after 500 h of continuous operation in N-2 atmosphere under one-sun illumination. The key to this striking performance of these PSCs is the formation of a full-coverage, stable native-oxide layer, which fully encapsulates and passivates the perovskite surfaces. The native-oxide passivation approach reported here represents an alternate avenue for boosting the efficiency and stability of lead-free PSCs.
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| 17. |
- Dou, Tianyi, et al.
(författare)
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Nanoscale Structural Characterization of Individual Viral Particles Using Atomic Force Microscope Infrared (AFM-IR) and Tip-Enhanced Raman Spectroscopy (TERS)
- 2020
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 92:16, s. 11297-11304
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Tidskriftsartikel (refereegranskat)abstract
- Viruses are infections species that infect a large spectrum of living systems. Although displaying a wide variety of shapes and sizes, they are all composed of nucleic acid encapsulated into a protein capsid. After virions enter the host cell, they replicate to produce multiple copies of themselves. They then lyse the host, releasing virions to infect new cells. High proliferation rate of viruses is the underlying cause of their fast transmission among living species. Although many viruses are harmless, some of them are responsible for severe diseases such as AIDS, viral hepatitis and flu. Traditionally, electron microscopy is used to identify and characterize viruses. This approach is time and labor consuming, which is problematic upon pandemic proliferation of previously unknown viruses. Herein, we demonstrate a novel diagnosis approach for label-free identification and structural characterization of individual viruses that is based on a combination of nanoscale Raman and Infrared spectroscopy. Using atomic force microscopy infrared spectroscopy (AFM-IR), we were able to probe structural organization of the virions of herpes simplex type 1 viruses and bacteriophage MS2. We also showed that tip enhanced Raman spectroscopy could be used to reveal protein secondary structure and amino acid composition of the virus surface. Our results show that AFM-IR and TERS provide different but complimentary information about the structure of complex biological specimens. This structural information can be used for fast and reliable identification of viruses. This nanoscale bimodal imaging approach can be also used to investigate the origin of viral polymorphism and study mechanisms of virion assembly.
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| 18. |
- Lei, Yu, et al.
(författare)
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Graphene and Beyond: Recent Advances in Two-Dimensional Materials Synthesis, Properties, and Devices
- 2022
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Ingår i: ACS Nanoscience Au. - : American Chemical Society (ACS). - 2694-2496. ; 2:6, s. 450-485
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Forskningsöversikt (refereegranskat)abstract
- Since the isolation of graphene in 2004, two-dimensional (2D) materials research has rapidly evolved into an entire subdiscipline in the physical sciences with a wide range of emergent applications. The unique 2D structure offers an open canvas to tailor and functionalize 2D materials through layer number, defects, morphology, moiré pattern, strain, and other control knobs. Through this review, we aim to highlight the most recent discoveries in the following topics: theory-guided synthesis for enhanced control of 2D morphologies, quality, yield, as well as insights toward novel 2D materials; defect engineering to control and understand the role of various defects, including in situ and ex situ methods; and properties and applications that are related to moiré engineering, strain engineering, and artificial intelligence. Finally, we also provide our perspective on the challenges and opportunities in this fascinating field.
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| 19. |
- Qiao, Xinyu, et al.
(författare)
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Multi-objective optimization of building integrated photovoltaic windows in office building
- 2024
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Ingår i: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 318
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Tidskriftsartikel (refereegranskat)abstract
- Building-Integrated Photovoltaics (BIPV) offer a promising solution to enhance building energy efficiency and reduce building energy consumption. Among the various application of BIPV, BIPV windows stand out as an intriguing and notable example. This paper investigates an office building with BIPV windows in five different climatic cities in China. The study considers four variables, including building orientation (BO), window size (WZ), window visible light transmittance (VLT), and type of PV (TOPV). The objective is to minimize both the annual net electricity cost (ANEC) and the extra investment cost of BIPV windows. To simulate the design variables and objective functions, the jEPlus software is employed. Additionally, the jEPlus + EA software uses the SRC and Morris algorithms for sensitivity analysis of design parameters. The multi-objective problem is addressed using the NSGA-II. By conducting optimization, a set of Pareto optimal solutions were obtained. The results demonstrate that the building with BIPV windows can save a minimum of 6.83 % annual electricity costs. Moreover, the static investment payback period for all cities ranges from 7 to 14 years, indicating the economic feasibility of implementing BIPV windows.
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| 20. |
- Ren, Jiaying, et al.
(författare)
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RFI Mitigation for UWB Radar Via Hyperparameter-Free Sparse SPICE Methods
- 2019
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Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0196-2892 .- 1558-0644. ; 57:6, s. 3105-3118
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Tidskriftsartikel (refereegranskat)abstract
- Radio frequency interference (RFI) causes serious problems to ultrawideband (UWB) radar operations due to severely degrading radar imaging capability and target detection performance. This paper formulates proper data models and proposes novel methods for effective RFI mitigation. We first apply the single-snapshot Sparse Iterative Covariance-based Estimation (SPICE) algorithm to data from each pulse repetition interval for RFI mitigation and discuss the connection of SPICE to the l(1)-penalized least absolute deviation (l(1)-PLAD) approach. Then, we devise a modified group SPICE algorithm and we prove that it is equivalent to a special case of the l(1,2)-PLAD method. The modified group SPICE algorithm can be applied to data from a coherent processing interval for effective RFI mitigation. Both the single-snapshot SPICE and the modified group SPICE methods simultaneously exploit the sparsity properties of both RFI spectrum and UWB radar target echoes. Unlike the existing sparsity-based RFI suppression methods, such as the robust principal component analysis algorithm, the proposed methods are hyperparameter-free and therefore easier to use in practical applications. Furthermore, the fast implementation of the SPICE methods is considered by exploiting the special structures of both single-snapshot and multiple-snapshot covariance matrices. Finally, the results obtained from applying the SPICE methods to simulated data as well as measured data collected by the U.S. Army Research Laboratory synthetic aperture radar system are presented to demonstrate the effectiveness of the proposed methods.
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| 21. |
- Ren, Jiaying, et al.
(författare)
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Sinusoidal parameter estimation from signed measurements obtained via time-varying thresholds
- 2018
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Ingår i: Proc. 52nd Asilomar Conference on Signals, Systems, and Computers. - Piscataway, NJ : IEEE. - 9781538692189 ; , s. 1111-1115
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Konferensbidrag (refereegranskat)abstract
- We consider the problem of sinusoidal parameter estimation using signed observations obtained via one-bit sampling with time-varying thresholds. In a previous paper, a relaxation based algorithm, referred to as IbRELAX, has been proposed to iteratively maximize the likelihood function. However, IbRELAX can only he used in applications involving a small number of sinusoids due to the time-consuming exhaustive search procedure needed in each iteration. In this paper, we present a majorizalion-minimization (MM) based IbRELAX algorithm, referred to as IbMMRELAX, to enhance the computational efficiency of IbRELAX. Using the MM technique, IbMMRELAX maximizes the likelihood function iteratively using simple FFT operations to reduce the computational cost of IbRELAX while maintaining its excellent estimation accuracy. Numerical examples are presented to demonstrate the effectiveness of the proposed method.
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| 22. |
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| 23. |
- Wang, Meiyang, et al.
(författare)
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Alkali Metal Cations as Charge-Transfer Bridge for Polarization Promoted Solar-to-H2 Conversion
- 2023
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 33:9
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Tidskriftsartikel (refereegranskat)abstract
- Utilization of spontaneous polarization electric field of ferroelectric materials to realize the spatial separation and fast transfer of photogenerated charges has been regarded as a promising strategy to fabricate highly efficient photocatalysts. Herein, a novel heterostructure is constructed by coupling potassium poly(heptazine imide) (K-PHI) with ferroelectric BaxSr1-xTiO3 (BxST) through a facile electrostatic self-assembly strategy. The ionic species of K-PHI can neutralize the polarized charges in BxST to form intimate interfacial contact, substantially boosting the internal electric field. Notably, K+ cations intercalated into K-PHI act as charge-transfer bridge to promote migration and separation of photogenerated charge carriers. As a result, a significantly improved H2-evolution rate of 1087.4 µmol h−1 g−1 with an apparent quantum yield (AQY) of 8.05% at 420 nm is achieved over 5% K-PHI/B0.8ST, standing among the best polymeric carbon nitride-based photocatalysts reported up to date. Moreover, the extreme stability of the catalysts is evidenced by remaining outstanding catalytic performance even after storage for half a year. This strategy can be extended to other alkali metal (Na+ and Cs+) modified polymeric materials, highlighting the key role of the bridging ions in constructing polarized heterostructure, which sheds light on the design of ferroelectric-assisted photocatalysts.
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| 24. |
- Yang, Jianming, et al.
(författare)
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Extremely Low-Cost and Green Cellulose Passivating Perovskites for Stable and High-Performance Solar Cells
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 11:14, s. 13491-13498
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Tidskriftsartikel (refereegranskat)abstract
- The fast evolution of metal halide perovskite solar cells has opened a new chapter in the field of renewable energy. High-quality perovskite films as the active layers are essential for both high efficiency and long-term stability. Here, the perovskite films with enlarged crystal grain size and decreased defect density are fabricated by introducing the extremely low-cost and green polymer, ethyl cellulose (EC), into the perovskite layer. The addition of EC triggers hydrogen bonding interactions between EC and the perovskite, passivating the charge defect traps at the grain boundaries. The long chain of EC further acts as a scaffold for the perovskite structure, eliminating the annealing-induced lattice strain during the film fabrication process. The resulting devices with the EC additive exhibit a remarkably enhanced average power conversion efficiency from 17.11 to 19.27% and an improvement of all device parameters. The hysteresis index is found to decrease by three times from 0.081 to 0.027, which is attributed to suppressed ion migration and surface charge trapping. In addition, the defect passivation by EC significantly improves the environmental stability of the perovskite films, yielding devices that retain 80% of their initial efficiency after 30 days in ambient air at 45% relative humidity, whereas the pristine devices without EC fully degrade. This work provides a low-cost and green avenue for passivating defects that improves both the efficiency and operational stability of perovskite solar cells.
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| 25. |
- Zhang, Chao, et al.
(författare)
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All-trans retinoic acid prevents epidural fibrosis through NF-kappa B signaling pathway in post-laminectomy rats
- 2014
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Ingår i: Neuropharmacology. - : Elsevier BV. - 0028-3908 .- 1873-7064. ; 79C, s. 275-281
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Tidskriftsartikel (refereegranskat)abstract
- Laminectomy is a widely accepted treatment for lumbar disorders, and epidural fibrosis (EF) is a common complication. EF is thought to cause post-operative pain recurrence after laminectomy or discectomy. All-trans retinoic acid (ATRA) has shown anti-fibrotic, anti-inflammatory, and anti-proliferative functions. The object of this study was to investigate the effects of ATRA on the prevention of EF in post-laminectomy rats. In vitro, the anti-fibrotic effect of ATRA was demonstrated with cultured fibroblasts count, which comprised of those that were cultured with/without ATRA. In vivo, rats underwent laminectomy at the L1-L2 levels. We first demonstrated the beneficial effects using 0.05% ATRA compared to vehicle (control group). We found that a higher concentration of ATRA (0.1%) achieved dose-dependent results. Hydroxyproline content, Rydell score, vimentin-positive cell density, fibroblast density, inflammatory cell density and inflammatory factor expression levels all suggested better outcomes in the 0.1% ATRA rats compared to the other three groups. Presumably, these effects involved ATRA's ability to suppress transforming growth factor (TGF-β1) and interleukin (IL)-6 which was confirmed with reverse-transcriptase polymerase chain reaction (RT-PCR). Finally we demonstrated that ATRA down-regulated nuclear factor (NF)-κB by immunohistochemistry and western blotting for p65 and inhibition of κB (IκBα), respectively. Our findings indicate that topical application of ATRA can inhibit fibroblast proliferation, decrease TGF-β1 and IL-6 expression level, and prevent epidural scar adhesion in rats. The highest concentration employed in this study (0.1%) was the most effective. ATRA suppressed EF through down-regulating NF-κB signaling, whose specific mechanism is suppression of IκB phosphorylation and proteolytic degradation.
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| 26. |
- Zhang, Peili, et al.
(författare)
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A Molecular Copper Catalyst for Electrochemical Water Reduction with a Large Hydrogen-Generation Rate Constant in Aqueous Solution
- 2014
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 53:50, s. 13803-13807
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Tidskriftsartikel (refereegranskat)abstract
- The copper complex [(bztpen)Cu](BF4)(2) (bztpen=N-benzyl-N,N,N-tris(pyridin-2-ylmethyl)ethylenediamine) displays high catalytic activity for electrochemical proton reduction in acidic aqueous solutions, with a calculated hydrogen-generation rate constant (k(obs)) of over 10000s(-1). A turnover frequency (TOF) of 7000h(-1)cm(-2) and a Faradaic efficiency of 96% were obtained from a controlled potential electrolysis (CPE) experiment with [(bztpen)Cu](2+) in pH2.5 buffer solution at -0.90V versus the standard hydrogen electrode (SHE) over two hours using a glassy carbon electrode. A mechanism involving two proton-coupled reduction steps was proposed for the dihydrogen generation reaction catalyzed by [(bztpen)Cu](2+).
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| 27. |
- Zhang, Tianyi, et al.
(författare)
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Joint RFI mitigation and radar echo recovery for one-bit UWB radar
- 2022
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Ingår i: Signal Processing. - : Elsevier. - 0165-1684 .- 1872-7557. ; 193
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Tidskriftsartikel (refereegranskat)abstract
- A B S T R A C T Radio frequency interference (RFI) mitigation and radar echo recovery are critically important for the proper functioning of ultra-wideband (UWB) radar systems using one-bit sampling techniques. We re-cently introduced a technique for one-bit UWB radar, which first uses a majorization-minimization method for RFI parameter estimation followed by a sparse method for radar echo recovery. However, this technique suffers from high computational complexity due to the need to estimate the parameters of each RFI source separately and iteratively. In this paper, we present a computationally efficient joint RFI mitigation and radar echo recovery framework to greatly reduce the computational cost. Specifically, we exploit the sparsity of RFI in the fast-frequency domain and the sparsity of radar echoes in the fast -time domain to design a one-bit weighted SPICE (SParse Iterative Covariance-based Estimation) based framework for the joint RFI mitigation and radar echo recovery of one-bit UWB radar. Both simulated and experimental results are presented to show that the proposed one-bit weighted SPICE framework can not only reduce the computational cost but also outperform the existing approach for decoupled RFI mitigation and radar echo recovery of one-bit UWB radar.(c) 2021 Elsevier B.V. All rights reserved.
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| 28. |
- Zhang, Tianyi, et al.
(författare)
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RFI Mitigation for One-Bit UWB Radar Systems
- 2022
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Ingår i: IEEE Transactions on Aerospace and Electronic Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9251 .- 1557-9603. ; 58:2, s. 879-889
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Tidskriftsartikel (refereegranskat)abstract
- Radio frequency interference (RFI) mitigation is critical to the proper operation of ultrawideband (UWB) radar systems because RFI can severely degrade the radar imaging capability and target detection performance. In this article, we address the RFI mitigation problem for one-bit UWB radar systems. A one-bit UWB system obtains its signed measurements via a low-cost and high rate sampling scheme, referred to as the continuous time binary value (CTBV) technology. This sampling strategy compares the signal to a known threshold that varies with slow-time and can be used to achieve a high sampling rate and quantization resolution with simple and affordable hardware. This article establishes a proper data model for the RFI sources and proposes a novel RFI mitigation method for the one-bit UWB radar system that uses the CTBV sampling technique. Specifically, we model the RFI sources as a sum of sinusoids with frequencies fixed during the coherent processing interval (CPI) and we exploit the sparsity of the RFI spectrum. We use an extended majorization-minimization-based 1bRELAX algorithm, referred to as 1bMMRELAX, to estimate the RFI source parameters from the signed measurements obtained by using the CTBV sampling strategy. We also devise a new fast frequency initialization method for the extended 1bMMRELAX algorithm to improve its computational efficiency. Moreover, a sparse method is introduced to recover the desired radar echoes using the estimated RFI parameters. Both simulated and experimental results are presented to demonstrate that our proposed algorithm outperforms the existing digital integration method, especially for severe RFI cases.
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