Ambient pollutants are associated with clinical and sub-clinical indicators of infertility, such as poor sperm quality. However, the link between the ambient fine particle (PM2.5) concentration and the fertility rate (FR) is unclear. In this epidemiological study, we examined the association between PM2.5 concentration and childlessness in the United States (US). We conducted a nationwide spatiotemporal study of ~29 million births in 520 US counties from 2003 to 2011. We obtained monthly numbers and demographic data of newborns from the Centers for Disease Control and Prevention, and PM2.5 estimates from a downscaling model of in situ observations and outputs from the Community Multiscale Air Quality Model. We evaluated the association between the mean PM2.5 concentration and the FR during the gestational (0–8 months before birth) and pre-gestational (9–11 months before birth) periods using a Poisson model with demographic and socioeconomic covariates. We found a significant association between the FR and PM2.5 exposure during pre-gestation but not gestation. Each 5 μg/m3 increase in pre-gestational PM2.5 exposure was associated with a 0.7% (0.0%, 1.4%) reduction in the FR. Nonlinear analysis suggested a sublinear association between the reduction in the FR and PM2.5 concentration without a safety threshold. Additionally, an annual mean reduction of 1.16 (1.15, 1.17) births per 1000 females aged 15–44 years was attributable to PM2.5. This study established, for the first time, an association in the US between the FR and PM2.5 concentration, a finding that adds to the extant epidemiological evidence of the effects of ambient pollutants on fertility, and extends the scope of the impact of low air quality on health.
Hypertensive disorders in pregnancy harm both maternal and infant health and have been linked to ambient particulate matter. However, existing studies are restricted to a local scale and remain inconsistent. A large-scale study is required to enrich the epidemiological evidence and explore the potential sources of the inconsistency. Making use of US birth certificates (1999-2004), and monitoring data from the environmental protection agency air quality networks, we associated hypertensive disorders in pregnancy with maternal exposure to fine particles or coarse particles using logistic regression analysis after adjusting for many covariates among >5 million subjects in the contiguous United States. Additional analyses were conducted to examine variations in the associations according to (1) census divisions; (2) individual-level factors; (3) a socioeconomic indicator, county-level poverty; and (4) the concentration of ambient particles. The results indicated that hypertensive disorders in pregnancy were robustly linked to maternal exposure to fine particles with an adjusted odds ratio of 1.10 (95% confidence intervals, 1.08-1.12) per 5 mu g/m(3) increment in terms of the entire pregnancy mean. Stronger associations were found among white mothers. There were also considerable variations in the association by census division or poverty level among counties. Nonlinear analysis indicated a sublinear dose-response function with a threshold concentration of 9 g/m(3). Based on the national study, we calculated the population attributable fractions and found that 8.1% (6.8%-9.4%) of hypertensive disorder cases were attributable to an entire pregnancy exposure of fine particles. These findings can help policymakers to plan related interventions.
In this review paper, we synthesize the current knowledges about bacteria in atmospheric waters, e.g., cloud, fog, rain, and snow, most of which were obtained very recently. First, we briefly describe the importance of bacteria in atmospheric waters, i.e., the essentiality of studying bacteria In atmospheric waters in understanding aerosol-cloud-precipitation-climate interactions in the Earth system. Next, approaches to collect atmospheric water samples for the detection of bacteria and methods to identify the bacteria are summarized and compared. Then the available data on the abundance, viability and community composition of bacteria in atmospheric waters are summarized. The average bacterial concentration in cloud water was usually on the order 10(4)-10(5) cells mL(-1), while that in precipitation on the order 10(3)-10(4) cells mL(-1). Most of the bacteria were viable or metabolically active. Their community composition was highly diverse and differed at various sites. Factors potentially influencing the bacteria, e.g., air pollution levels and sources, meteorological conditions, seasonal effect, and physicochemical properties of atmospheric waters, are described. After that, the implications of bacteria present in atmospheric waters, including their effect on nucleation in clouds, atmospheric chemistry, ecosystems and public health, are briefly discussed. Finally, based on the current knowledges on bacteria in atmospheric waters, which in fact remains largely unknown, we give perspectives that should be paid attention to in future studies.
Monolayer transition metal dichalcogenides (TMDs) have become essential two-dimensional materials for their perspectives in engineering next-generation electronics. For related applications, the controlled growth of large-area uniform monolayer TMDs is crucial, while it remains challenging. Herein, we report the direct synthesis of 6-inch uniform monolayer molybdenum disulfide on the solid soda-lime glass, through a designed face-to-face metal-precursor supply route in a facile chemical vapor deposition process. We find that the highly uniform monolayer film, with the composite domains possessing an edge length larger than 400 µm, can be achieved within a quite short time of 8 min. This highly efficient growth is proven to be facilitated by sodium catalysts that are homogenously distributed in glass, according to our experimental facts and density functional theory calculations. This work provides insights into the batch production of highly uniform TMD films on the functional glass substrate with the advantages of low cost, easily transferrable, and compatible with direct applications.
One challenge in merging community and ecosystem ecology is to integrate the complexity of natural multitrophic communities into concepts of ecosystem functioning. Here, we combine food‐web and allometry theories to demonstrate that primary production, as measured by the total nutrient uptake of the multitrophic community, is determined by vertical diversity (i.e. food web's maximum trophic level) and structure (i.e. distributions of species and their abundances and metabolic rates across trophic levels). In natural ecosystems, the community size distribution determines all these vertical patterns and thus the total nutrient uptake. Our model suggests a vertical diversity hypothesis (VDH) for ecosystem functioning in complex food webs. It predicts that, under a given nutrient supply, the total nutrient uptake increases exponentially with the maximum trophic level in the food web and it increases with its maximum body size according to a power law. The VDH highlights the effect of top–down regulation on plant nutrient uptake, which complements traditional paradigms that emphasised the bottom–up effect of nutrient supply on vertical diversity. We conclude that the VDH contributes to a synthetic framework for understanding the relationship between vertical diversity and ecosystem functioning in food webs and predicting the impacts of global changes on multitrophic ecosystems.
Chromium contamination can be remediated by catalytic reduction with precious metal palladium (Pd). Thus, enhancing Pd catalytic performance is of strong interest. An environmentally friendly and nontoxic approach for production of palladium nanoparticles (Pd-NPs) is to use microorganisms. Herein, the biosynthesis of Pd-NPs by Shewanella loihica PV-4 is reported for the first time. Both extracellular and intracellular bioreduction of Pd(II) has contributed this bio-fabrication, with the production of Pd0 particles in the size range of 4-10 nm. It was found that several factors including a higher initial Pd(II) concentration, weak acid medium condition, and a lager dosage of sodium formate and biomass amount could facilitate this synthesis process. The biosynthesized Pd-NPs exhibited excellent catalytic activities for chromium (VI) reduction, with complete removal of Cr(VI) after 3-h operation with a catalyst amount of 0.5 mg/mL, an initial Cr(VI) concentration of 0.5 mM, and formic acid as electron donor; these are significant advantages to chemically prepared Pd0. Cr(VI) reduction catalyzed by biosynthesized Pd-NPs was promoted with factors such as a higher dosage of formic acid, lower pH, and a lower initial Cr(VI) concentration. Density functional theory calculations of formic acid decomposition on Pd-NPs revealed that Pd-NPs facilitated formic acid to decompose into CO2 and H2. These results have collectively demonstrated the feasibility of the biosynthesis of Pd-NPs by Shewanella loihica PV-4 and its potential application as a promising catalyst for remediation of chromium contamination.
BACKGROUND/OBJECTIVES: Prenatal growth, which is widely marked by birthweight, may have a pivotal role in affecting the lifelong risk of cardiometabolic disorders; however, comprehensive evaluation of its relations with childhood cardiometabolic risk patterns and the ethnic and gender disparities in national representative populations is still lacking. The aim of this study was to evaluate the associations between birthweight and comprehensive patterns of cardiometabolic risk in a nationally representative sample of children and adolescents. SUBJECTS/METHODS: Prospective analyses were performed using data from 28 153 children 0 to 15 years in the National Health and Nutrition Examination Survey from 1999 through 2014. We defined childhood cardiometabolic disorders using standard definitions for obesity, high blood pressure, hyperglycemia and dyslipidemia. RESULTS: Five birthweight categories <2.5, 2.5-3.0, 3.0-3.5, 3.5-4.2 and 4.2 kg accounted for 8.2%, 17.9%, 35.7%, 27.9% and 10.4% of the population, respectively. In all children, with increasing birthweight, we observed significantly increasing trends of the risk of general and central obesity (P for trend <0.01) and significantly decreasing trends of the risk of high systolic blood pressure (SBP), high HbA1c and low high-density lipoprotein cholesterol (HDL-C) (P for trend <0.05). The associations were independent of current body mass index (BMI). In addition, we found that the relations of birthweight with high waist circumference in Black children showed U-shape, as well as high SBP in Mexican and Hispanic children. Moreover, we found that the associations of low birthweight with high SBP and low HDL-C appeared to more prominent significant in boys, whereas the inverse association with high HbA1c was more evident in girls. CONCLUSIONS: Our data indicate that birthweight is significantly related to childhood cardiometabolic risk, independent of current BMI, and the associations exhibit race and gender-specific patterns.
An all-optical scheme is proposed for studying laser plasma based incoherent photon emission from inverse Compton scattering in the quantum electrodynamic regime. A theoretical model is presented to explain the coupling effects among radiation reaction trapping, the self-generated magnetic field and the spiral attractor in phase space, which guarantees the transfer of energy and angular momentum from electromagnetic fields to particles. Taking advantage of a prospective ∼ 10 23 W cm −2 laser facility, 3D particle-in-cell simulations show a gamma-ray flash with unprecedented multi-petawatt power and brightness of 1.7 × 10 23 photons s −1 mm −2 mrad −2 /0.1% bandwidth (at 1 GeV). These results bode well for new research directions in particle physics and laboratory astrophysics exploring laser plasma interactions.