Wildfire smoke exposure during pregnancy and perinatal, obstetric, and early childhood health outcomes: A systematic review and meta-analysis.

BACKGROUND: Maternal exposure to air pollution during pregnancy is associated with adverse birth outcomes, although less is known for wildfire smoke. This systematic review evaluated the association between maternal exposure to wildfire smoke during pregnancy and the risk of perinatal, obstetric, and early childhood health outcomes. METHODS: We searched CINAHL Complete, Ovid/EMBASE, Ovid/MEDLINE, ProQuest, PubMed, Scopus, Web of Science, and Google Scholar to identify relevant epidemiological observational studies indexed through September 2023. The screening of titles, abstracts, and full-texts, data extraction, and risk of bias assessment was performed by pairs of independent reviewers. RESULTS: Our systematic search yielded 28,549 records. After duplicate removal, we screened 14,009 studies, identifying 31 for inclusion in the present review. Data extraction highlighted high methodological heterogeneity between studies, including a lack of geographic variation. Approximately 56.5% and 16% originated in the United States and Brazil, respectively, and fewer in other countries. Among the studies, wildfire smoke exposure during pregnancy was assessed using distance of residence from wildfire-affected areas (n = 15), measurement of air pollutant concentration during wildfires (n = 11), number of wildfire records (n = 3), aerosol index (n = 1), and geographic hot spots (n = 1). Pooled meta-analysis for birthweight and low birthweight were inconclusive, likely due to low number of methodologically homogenous studies. However, the reviewed studies provided suggestive evidence for an increased risk of birthweight reduction, low birthweight, preterm birth, and other adverse health outcomes. CONCLUSIONS: This review identified 31 studies evaluating the impacts of maternal wildfire smoke exposure on maternal, infant, and child health. Although we found suggestive evidence of harm from exposure to wildfire smoke during pregnancy, more methodologically homogenous studies are required to enable future meta-analysis with greater statistical power to more accurately evaluate the association between maternal wildfire smoke and adverse birth outcomes and other health outcomes.

Ultrafast Antisolvent Growth of Single-Crystal CsPbBr3 Microcavity for Whispering-Gallery-Mode Lasing.

In recent years, all-inorganic cesium lead bromide (CsPbBr3) perovskites have garnered considerable attention for their prospective applications in green photonics and optoelectronic devices. However, the development of efficient and economical methods to obtain high-quality micron-sized single-crystalline CsPbBr3 microplatelets (MPs) has become a challenge. Here, we report the synthesis of CsPbBr3 MPs on Si/SiO2 substrate by optimizing the ultrafast antisolvent method (FAS). This technique is able to produce well-dispersed, uniformly sized, and morphologically regular tetragonal phase single crystals, which can give strong green emission at room temperature, with excellent stability and excitonic character. Moreover, the crystals demonstrated lasing with a whispering gallery mode with a low threshold. These results suggest that the single-crystalline CsPbBr3 MPs synthesized by this method are of high optical quality, holding vast potential for future applications in photonic devices.

Mid-infrared carbon isotope spectrum logging system combined with a thermostat of optical subsystem for high-precision detection of isotope ratio.

In the process of oil and gas exploration and development, carbon isotope ratio can reflect the maturity of oil and gas and predict the recovery factor, and the isotope ratio in the composition of shale gas is particularly important. Thus, a carbon isotope spectrum logging system was designed and exploited based on tunable diode laser absorption spectroscopy (TDLAS) technology under the fundamental frequency absorption band of 12CO2 and 13CO2 molecules, and a quantum cascade laser (QCL) with center wavelength of 4.35 µm was applied. For further detection sensitivity, wavelength modulation spectroscopy (WMS) technology was combined to suppress background noise through the modulation of QCL. A multi-pass gas cell (MPGC) with an optical path length of 41 m was utilized for lower limit of detection (LoD). In order to suppress the temperature dependence of the absorption spectrum, the optical subsystem was placed in a high-precision thermostat to maintain a stable temperature, so as to achieve high-precision and high-stability detection. Meanwhile, sparrow search algorithm-back propagation (SSA-BP) was applied for concentration prediction of 12CO2 and 13CO2. Taking advantage of the excellent optimization ability, fast convergence speed and high stability of SSA, the problem that BP neural network algorithm is highly dependent on initial value can be solved to some extent. Sensor performance was validated through calibration and stability experiments. The LoD of 12CO2 reached a minimum of 0.618 parts-per-billion (ppb) with an 88 s averaging time, and the LoD of 13CO2 reached 0.181 ppb when the averaging time was 96 s. Besides, the standard deviation of carbon isotope ratio obtained by this system was âˆ¼ 0.61 ‰. The results illustrate that this self-developed sensor has a bright prospect in the field of shale gas isotope detection.

CD44 Is Associated with Poor Prognosis of ccRCC and Facilitates ccRCC Cell Migration and Invasion through HAS1/MMP9.

BACKGROUND: In many solid tumors, CD44 has been identified as a cancer stem cell marker as well as an important molecular in cancer progression and metastasis, making it attractive for potential therapeutic applications. However, our knowledge of the biological function and mechanism of CD44 in clear cell renal cell carcinoma (ccRCC) is limited. METHODS: In this study, the expression, prognostic values and functional enrichment analysis of CD44 in ccRCC were analyzed using public databases. Quantitative real-time PCR (qRT-PCR), Western blotting, and immunohistochemical (IHC) assays were taken to detect CD44 expression in ccRCC tissues. The effects of CD44 on the proliferation, migration and invasion of ccRCC cells were investigated by gain-of-function and loss-of-function experiments. Subcutaneous models further confirmed the role of CD44 in tumor growth. The relationship between CD44, HAS1 and MMP9 was investigated to uncover the regulatory mechanism of CD44 in ccRCC. RESULTS: CD44 was significantly upregulated in ccRCC and associated with poor overall survival (OS). Based on the functional enrichment analysis and PPI network, we found that CD44 had associations with ECM interaction and focal adhesion pathway. Clinical ccRCC sample validation revealed that CD44 mRNA and protein expression were significantly increased in ccRCC tissues, and strong CD44 staining was observed in four metastatic ccRCC cases. In vitro experiments showed that CD44 overexpression promoted cell proliferation, migration and invasion. In vivo experiments also demonstrated that CD44 overexpression accelerated tumor formation in mice. Finally, we found that CD44 regulates the expression of HAS1 in ccRCC, which is essential for the secretion of MMP9 and cell migratory ability. CONCLUSION: The upregulation of CD44 mRNA and protein expressions in ccRCC is indicative of unfavorable clinical prognoses. The CD44/HAS1/MMP9 axis is believed to exert a significant influence on the regulation of ECM degradation and ccRCC metastasis.

ATAD2 promotes glycolysis and tumor progression in clear cell renal cell carcinoma by regulating the transcriptional activity of c-Myc.

Clear cell renal cell carcinoma (ccRCC) is a common malignant tumor of the urogenital tract. Given that ccRCC is often resistant to radiotherapy and traditional chemotherapy, the clinical treatment of patients with ccRCC remains a challenge. The present study found that ATAD2 was significantly upregulated in ccRCC tissues. In vitro and in vivo experiments showed that the inhibition of ATAD2 expression mitigated the aggressive phenotype of ccRCC. ATAD2 was also associated with glycolysis in ccRCC. Interestingly, we found that ATAD2 could physically interact with c-Myc and promote the expression of its downstream target gene, thereby enhancing the Warburg effect of ccRCC. Overall, our study emphasizes the role of ATAD2 in ccRCC. The targeted expression or functional regulation of ATAD2 could be a promising method to reduce the proliferation and progression of ccRCC.

Spatiotemporally continuous estimates of daily 1-km PM2.5 concentrations and their long-term exposure in China from 2000 to 2020.

Monitoring long-term variations in fine particulate matter (PM2.5) is essential for environmental management and epidemiological studies. While satellite-based statistical/machine-learning methods can be used for estimating high-resolution ground-level PM2.5 concentration data, their applications have been hindered by limited accuracy in daily estimates during years without PM2.5 measurements and massive missing values due to satellite retrieval data. To address these issues, we developed a new spatiotemporal high-resolution PM2.5 hindcast modeling framework to generate the full-coverage, daily, 1-km PM2.5 data for China for the period 2000-2020 with improved accuracy. Our modeling framework incorporated information on changes in observation variables between periods with and without monitoring data and filled gaps in PM2.5 estimates induced by satellite data using imputed high-resolution aerosol data. Compared to previous hindcast studies, our method achieved superior overall cross-validation (CV) R2 and root-mean-square error (RMSE) of 0.90 and 12.94 µg/m3 and significantly improved the model performance in years without PM2.5 measurements, raising the leave-one-year-out CV R2 [RMSE] to 0.83 [12.10 µg/m3] at a monthly scale (0.65 [23.29 µg/m3] at a daily scale). Our long-term PM2.5 estimates show a sharp decline in PM2.5 exposure in recent years, but the national exposure level in 2020 still exceeded the first annual interim target of the 2021 World Health Organization air quality guidelines. The proposed hindcast framework represents a new strategy to improve air quality hindcast modeling and can be applied to other regions with limited air quality monitoring periods. These high-quality estimates can support both long- and short-term scientific research and environmental management of PM2.5 in China.

L1CAM deployed perivascular tumor niche promotes vessel wall invasion of tumor thrombus and metastasis of renal cell carcinoma.

The survival of tumor cells in the bloodstream, and vasculature adhesion at metastatic sites are crucial for tumor metastasis. Perivascular invasion aids tumor cell self-renewal, survival, and formation of metastases by facilitating readily available oxygen, nutrients, and endothelial-derived paracrine factors. Renal cell carcinoma (RCC) is among the most prevalent tumors of the urinary system, and the formation of venous tumor thrombus (VTT) is a characteristic feature of RCC. We observed high expression of L1CAM in the VTT with vessel wall invasion. L1CAM promotes the adhesion, migration, and invasion ability of RCC and enhances metastasis by interacting with ITGA5, which elicits activation of signaling downstream of integrin α5ß1. L1CAM promotes ADAM17 transcription to facilitate transmembrane ectodomain cleavage and release of soluble L1CAM. In response to soluble L1CAM, vascular endothelial cells release several cytokines and chemokines. Endothelial-derived CXCL5 and its receptor CXCR2 promote the migration and intravasation of RCC toward endothelial cells suggesting that crosstalk between endothelial cells and tumor cells has a direct guiding role in driving the metastatic spread of RCC. LICAM plays a crucial role in the invasive ability of RCC, and regulation of L1CAM expression may contribute therapeutically to preventing RCC progression.

TPM2 attenuates progression of prostate cancer by blocking PDLIM7-mediated nuclear translocation of YAP1.

BACKGROUND: Prostate cancer (PCa) is a common malignant tumor of the genitourinary system. Clinical intervention in advanced PCa remains challenging. Tropomyosins 2 (TPM2) are actin-binding proteins and have been found as a biomarker candidate for certain cancers. However, no studies have explored the role of TPM2 in PCa and its regulatory mechanism. METHODS: TPM2 expression was assessed in Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) PCa patient dataset. The effect of TPM2 on PCa progression was assessed in vitro and in vivo by quantifying proliferation, migration, invasion and tumor growth assays, and the mechanism of TPM2 in PCa progression was gradually revealed by Western blotting, immunoprecipitation, and immunofluorescence staining arrays. RESULTS: TPM2 was found to be severely downregulated in tumor tissues of PCa patients compared with tumor-adjacent normal tissues. In vitro experiments revealed that TPM2 overexpression inhibited PCa cell proliferation, invasion and androgen-independent proliferation. Moreover, TPM2 overexpression inhibited the growth of subcutaneous xenograft tumors in vivo. Mechanistically, this effect was noted to be dependent on PDZ-binding motif of TPM2. TPM2 competed with YAP1 for binding to PDLIM7 through the PDZ-binding motif. The binding of TPM2 to PDLIM7 subsequently inhibited the nuclear transport function of PDLIM7 for YAP1. YAP1 sequestered in the cytoplasm phosphorylated at S127, resulting in its inactivation or degradation which in turn inhibited the expression of YAP1 downstream target genes. CONCLUSIONS: This study investigated the role of TPM2, PDLIM7, and YAP1 in PCa progression and castration resistance. TPM2 attenuates progression of PCa by blocking PDLIM7-mediated nuclear translocation of YAP1. Accordingly, targeting the expression or functional modulation of TPM2, PDLIM7, or YAP1 has the potential to be an effective therapeutic approach to reduce PCa proliferation and prevent the progression of castration-resistant prostate cancer (CRPC).

Neighborhood built environments and cognition in later life.

Objectives: Maintaining good cognition is crucial in later life. However, most existing research has focused on individual factors impacting cognition, and few studies have investigated the association between neighborhood built environment and older adults' cognition. This study examined the association between neighborhood built environment and cognition among community-dwelling older adults and identified variations in this association between different age groups in the older population.Methods: Data were derived from a cross-sectional survey of 1873 people aged 65 years and above in Hong Kong. We merged individual data from the survey with neighborhood built environment data based on community auditing and geographical information system. After controlling for individual covariates, we used multivariable linear regression to examine the association between neighborhood built environment and cognition.Results: Residents aged 80 and younger in neighborhoods with a higher land-use mix and more public transport terminals exhibited better cognition. Only the number of community centers in a neighborhood was positively associated with cognition for people older than 80.Conclusion: The built environment creates diverse impacts on different age groups among older adults. Our findings provide useful information for urban planners and policymakers for planning community facilities and built environments that consider the needs of different age groups within the older population.

Racial/Ethnic Inequity in Transit-Based Spatial Accessibility to COVID-19 Vaccination Sites.

With the ongoing spread of COVID-19, vaccination stands as an effective measure to control and mitigate the impact of the disease. However, due to the unequal distribution of COVID-19 vaccination sites, people can have different levels of spatial accessibility to COVID-19 vaccination. This study adopts an improved gravity-based model to measure the racial/ethnic inequity in transit-based spatial accessibility to COVID-19 vaccination sites in the Chicago Metropolitan Area. The results show that Black-majority and Hispanic-majority neighborhoods have significantly lower transit-based spatial accessibility to COVID-19 vaccination sites compared to White-majority neighborhoods. This research concludes that minority-dominated inner-city neighborhoods, despite better public transit coverage, are still disadvantaged in terms of transit-based spatial accessibility to COVID-19 vaccination sites. This is probably due to their higher population densities, which increase the competition for the limited supply of COVID-19 vaccination sites within each catchment area.

SOCS2-enhanced ubiquitination of SLC7A11 promotes ferroptosis and radiosensitization in hepatocellular carcinoma.

Radioresistance is a principal culprit for the failure of radiotherapy in hepatocellular carcinoma (HCC). Insights on the regulation genes of radioresistance and underlying mechanisms in HCC are awaiting for profound investigation. In this study, the suppressor of cytokine signaling 2 (SOCS2) were screened out by RNA-seq and bioinformatics analyses as a potential prognosis predictor of HCC radiotherapy and then were determined to promote radiosensitivity in HCC both in vivo or in vitro. Meanwhile, the measurements of ferroptosis negative regulatory proteins of solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4), intracellular lipid peroxidation and Fe2+ concentration suggested that a high level of ferroptosis contributed to the radiosensitization of HCC. Moreover, SOCS2 and SLC7A11 were expressed oppositely in HCC clinical tissues and tumour xenografts with different radiosensitivities. Mechanistically, the N-terminal domain of SLC7A11 was specifically recognized by the SH2-structural domain of SOCS2. While the L162 and C166 of SOCS2-BOX region could bind elongin B/C compound to co-form a SOCS2/elongin B/C complex to recruit ubiquitin molecules. Herein, SOCS2 served as a bridge to transfer the attached ubiquitin to SLC7A11 and promoted K48-linked polyubiquitination degradation of SLC7A11, which ultimately led to the onset of ferroptosis and radiosensitization of HCC. In conclusion, it was demonstrated for the first time that high-expressed SOCS2 was one of the biomarkers predicting radiosensitivity of HCC by advancing the ubiquitination degradation of SLC7A11 and promoting ferroptosis, which indicates that targeting SOCS2 may enhance the efficiency of HCC radiotherapy and improve the prognosis of patients.

Comparative analysis of surgical and oncologic outcomes of robotic, laparoscopic and open radical nephrectomy with venous thrombectomy: a propensity-matched cohort study.

OBJECTIVE: To provide insight into the surgical and oncological outcomes of robotic, laparoscopic and open radical nephrectomy with venous thrombectomy (RALRN-VT, LRN-VT, ORN-VT) in patients with renal tumor and venous thrombus. MATERIALS AND METHODS: A propensity-matched retrospective cohort study containing 324 patients with renal tumor and venous thrombus from January 2014 to August 2021 was analyzed. We compared surgical outcomes and we used the Kalan-Meier method to assess the overall survival (OS), tumor-specific survival (TSS), metastasis-free survival (MFS) and local recurrence-free survival (LRFS). The Pearson chi-square test and Fisher exact test, Wilcoxon rank sum test, Cox proportional hazards regression model and log-rank test were used. RESULTS: After matching, baseline characteristics were comparable in the RALRN-VT, LRN-VT and ORN-VT group. The RALRN-VT group had the least operative time (median 134 min vs 289 min vs 330 min, P < 0.001), the least blood loss (median 250 ml vs 500 ml vs 1000 ml, P < 0.001) and the fewest packed red blood cells transfusion (median 400 ml vs 800 ml vs 1200 ml, P < 0.001). The ORN-VT group had the highest complication rate (18.2 vs 22.7 vs 43.2%, P = 0.005), the highest Clavien grade (P = 0.001) and the longest postoperative hospital stay (median 7d vs 8d vs 10d, P < 0.001). No significant difference in OS, TSS and MFS between the minimally invasive procedures (MIP, including RALRN-VT and LRN-VT) group and ORN-VT group was found. The hazard ratio of LRFS for the MIP group was 0.20 (95% CI 0.06-0.70, P = 0.01) compared with ORN-VT group. CONCLUSIONS: RALRN-VT can result in the best surgical outcomes compared with LRN-VT and ORN-VT. The MIP group had a better LRFS compared with ORN-VT group.

Performance of a Mid-Infrared Sensor for Simultaneous Trace Detection of Atmospheric CO and N2O Based on PSO-KELM.

In this article, a field deployable sensor was developed using a self-developed 4.58-µm continuous wave quantum cascade laser (CW-QCL) for the simultaneous detection of carbon monoxide (CO) and nitrous oxide (N2O), both of which have strong fundamental absorption bands in this waveband. The sensor is based on tunable diode laser absorption spectroscopy (TDLAS) technology, which combined a multi-pass gas cell (MPGC) with a 41 m optical path length to achieve high-precision detection. Meanwhile, the particle swarm optimization-kernel extreme learning machine (PSO-KELM) algorithm was applied for CO and N2O concentration prediction. In addition, the self-designed board-level QCL driver circuit and harmonic signal demodulation circuit reduce the sensor cost and size. A series of validation experiments were conducted to verify the sensor performance, and experiments showed that the concentration prediction results of the PSO-KELM algorithm are better than those of the commonly used back propagation (BP) neural networks and partial least regression (PLS), with the smallest root mean square error (RMSE) and linear correlation coefficient closest to 1, which improves the detection precision of the sensor. The limit of detection (LoD) was assessed to be 0.25 parts per billion (ppb) for CO and 0.27 ppb for N2O at the averaging time of 24 and 38 s. Field deployment of the sensor was reported for simultaneous detection of CO and N2O in the air.

Contrasting inequality in human exposure to greenspace between cities of Global North and Global South.

The United Nations specified the need for "providing universal access to greenspace for urban residents" in the 11th Sustainable Development Goal. Yet, how far we are from this goal remains unclear. Here, we develop a methodology incorporating fine-resolution population and greenspace mappings and use the results for 2020 to elucidate global differences in human exposure to greenspace. We identify a contrasting difference of greenspace exposure between Global South and North cities. Global South cities experience only one third of the greenspace exposure level of Global North cities. Greenspace exposure inequality (Gini: 0.47) in Global South cities is nearly twice that of Global North cities (Gini: 0.27). We quantify that 22% of the spatial disparity is associated with greenspace provision, and 53% is associated with joint effects of greenspace provision and spatial configuration. These findings highlight the need for prioritizing greening policies to mitigate environmental disparity and achieve sustainable development goals.

Irradiation combined with PD-L1-/- and autophagy inhibition enhances the antitumor effect of lung cancer via cGAS-STING-mediated T cell activation.

Radiotherapy combined with immune checkpoint blockade has gradually revealed the superiority in the antitumor therapy; however, the contribution of host PD-L1 remains elusive. In this study, we found that the activation of CD8+ T cells was strikingly increased in both irradiated PD-L1-expressing primary tumor and distant non-irradiated syngeneic tumor in PD-L1-deficient mouse host, and thus enhanced radiation-induced antitumor abscopal effect (ATAE) by activating cGAS-STING pathway. Notably, the autophagy inhibitors distinctively promoted dsDNA aggregation in the cytoplasm and increased the release of cGAS-STING-regulated IFN-ß from irradiated cells, which further activated bystander CD8+ T cells to release IFN-γ and contributed to ATAE. These findings revealed a signaling cascade loop that the cytokines released from irradiated tumor recruit CD8+ T cells that in turn act on the tumor cells with amplified immune responses in PD-L1-deficient host, indicating a potential sandwich therapy strategy of RT combined with PD-L1 blockage and autophagy inhibition.

Beyond green environments: Multi-scale difference in human exposure to greenspace in China.

Greenspace exposure metrics can allow for comparisons of green space supply across time, space, and population groups, and for inferring patterns of variation in opportunities for people to enjoy the health and recreational benefits of nearby green environments. A better understanding of greenspace exposure differences across various spatial scales is a critical requirement for lessening environmental health disparities. However, existing studies are typically limited to a single city or across selected cities, which severely limits the use of results in measuring systemic national and regional scale differences that might need policy at above individual city planning level. To close this knowledge gap, our study aims to provide a holistic assessment of multi-scale greenspace exposure across provinces, cities, counties, towns, and land parcels for the whole of China. We mapped the nationwide fractional greenspace coverage at 10 m with Sentinel-2 satellite imagery, and then modeled population-weighted greenspace exposure to examine variation of greenspace exposure across scales. Our results show a prominent scaling effect of greenspace exposure across multi-scale administrative divisions in China, suggesting, as expected, an increase in heterogeneity with finer spatial scales. We also identify an asymmetric pattern of the difference between greenspace exposure and greenspace coverage, across a geo-demographic demarcation boundary (i.e., along the Heihe-Tengchong Line). In general, the greenspace coverage rate will overestimate more realistic human exposure to greenspace in East China while underestimating in West China. We further found that, in China, more recently urbanized areas have much better greenspace exposure than older urban areas. Our study provides a spatially explicit greenspace exposure metric for discovering multi-scale greenspace exposure difference, which will enhance governments' capacity to quantify environmental justice, detect vulnerable greenspace exposure risk hotspots, prioritize greenspace management at the supra-city scale, and monitor the balance between greenspace supply and demand.

Spatial uncertainty and environment-health association: An empirical study of osteoporosis among "old residents" in public housing estates across a hilly environment.

BACKGROUND: Built environment can influence physical conditions of older adults (e.g. osteoporosis). However, traditional methods using 2-dimensional circular buffer as a spatial structure to measure neighbourhood effect may create bias in health estimation, especially for the hilly and compact environment across low-income neighbourhoods (e.g. public housing estates). METHODS: We evaluated the environmental influences on self-reported osteoporosis among "old residents" (age≥65) in Hong Kong (n = 2077). Twelve public housing estates across hilly neighbourhoods in Hong Kong were selected as study sites. A cross-validated approach was developed to evaluate four spatial structures (2D circular, 2D service area, 3D circular, 3D service area). To determine problems of spatial uncertainty, we compared odds ratios (OR) and differences in effect sizes from models using different spatial structures. When all adjusted models achieve significant results based on 95% confidence intervals (CI) and with all positive/negative ORs, this study reported to have reached "a result with consistency". Results from the 3D service area were then used to explain the environment-health relationship. RESULTS: Different spatial structures can yield different results. Particularly, circular buffers overestimated environmental effects on self-reported osteoporosis. Overestimated measures were related to walkability and accessibility but not greenery. Specifically, results from the 3D service area showed that more public space and health facilities within a walkable distance (500 m) from a location of subject's residence were negatively associated with self-reported osteoporosis (adjusted ORs: 0.44 [0.29, 0.66]; 0.94 [0.90, 0.99]). However, more major transport facilities at the immediate distance from residence (200 m) was positively associated with self-reported osteoporosis (adjusted OR: 1.11 [1.01, 1.23]). CONCLUSIONS: Physical conditions (e.g. osteoporosis) of older adults living in a hilly neighbourhood could be driven by walking behaviours. It is necessary to include local terrain and road network to define a walkable neighbourhood for environment-health estimations to minimize spatial bias.

Realizing Single Chip White Light InGaN LED via Dual-Wavelength Multiple Quantum Wells.

Dual-wavelength multiple quantum wells (MQWs) have great potential in realizing high quality illumination, monolithic micro light-emitting diode (LED) displays and other related fields. Here, we demonstrate a single chip white light indium gallium nitride (InGaN) LED via the manipulation of the dual-wavelength MQWs. The MQWs contain four pairs of blue light-emitting MQWs and one pair of green light-emitting QW. The fabricated LED chips with nickel/gold (Ni/Au) as the current spreading layer emit white light with the injection current changing from 0.5 mA to 80 mA. The chromaticity coordinates of (0.3152, 0.329) closing to the white light location in the Commission International de I'Eclairage (CIE) 1931 chromaticity diagram are obtained under a 1 mA current injection with a color rendering index (CRI) Ra of 60 and correlated color temperature (CCT) of 6246 K. This strategy provides a promising route to realize high quality white light in a single chip, which will significantly simplify the production process of incumbent white light LEDs and promote the progress of high-quality illumination.

N-polar GaN Film Epitaxy on Sapphire Substrate without Intentional Nitridation.

High-temperature nitridation is commonly thought of as a necessary process to obtain N-polar GaN films on a sapphire substrate. In this work, high-quality N-polar GaN films were grown on a vicinal sapphire substrate with a 100 nm high-temperature (HT) AlN buffer layer (high V/III ratio) and without an intentional nitriding process. The smallest X-ray full width at half maximum (FWHM) values of the (002)/(102) plane were 237/337 arcsec. On the contrary, N-polar GaN film with an intentional nitriding process had a lower crystal quality. In addition, we investigated the effect of different substrate treatments 1 min before the high-temperature AlN layer's growth on the quality of the N-polar GaN films grown on different vicinal sapphire substrates.

Two-Step Deposition of an Ultrathin GaN Film on a Monolayer MoS2 Template.

Ultrathin gallium nitride (GaN) application can be profoundly influenced by its quality, especially the issue of amorphous interfacial layers formed on conventional substrates. Herein, we report a two-step deposition of an ultrathin GaN film via the plasma-enhanced atomic layer deposition (PEALD) technique on a mono-MoS2 template over a SiO2/Si substrate for quality improvement, by starting the deposition temperature at 260 °C and then ramping it to 320 °C. It was found that a lower initiating deposition temperature could be conducive to maintaining the mono-MoS2 template to support the subsequent growth of GaN. Compared to the control group of one-step high-temperature deposition at 320 °C, ideal layer-by-layer film growth is achieved at the low temperature of the two-step method instead of island formation, leading to the direct crystallization of GaN on the substrate with a rather sharp interface. Structural and chemical characterizations show that this two-step method produces a preferred [0001] orientation of the film originating from the interface region. Additionally, the improved two-step ultrathin GaN displays a smooth surface roughness as low as 0.58 nm, a low oxygen impurity concentration of 3.6%, and a nearly balanced Ga/N stoichiometry of 0.95:1. Our work paves a possible way to the feasible fabrication of ultrathin high-quality PEALD-GaN, and it is promising for better performance of relevant devices.