Microns In Diameter Research Articles

Specificfeatures of evolution of dense atomized superheated water plumes and peculiarities of its diagnostics

Experimental study of evolution of plumes of atomized metastable superheated water during its discharge through convergent-divergent nozzles is conducted. Dispersion characteristics of dense plumes in micron and submicron droplet diameter ranges are obtained. Theoretical and prediction analyses of different coagulation mechanisms in the considered two-phase flow are performed. The negligible effect of Brown-type coagulation is shown. It is also demonstrated that turbulent coagulation can change the fraction of micron-diameter droplets within 9%. In addition, for the first time, an “inertial” mechanism of coagulation is considered for the studied plumes under the conditions of plume baking in a cocurrent flow or in the ambient air. It can lead to a considerable decrease in the submicron-droplet mass fraction, which is observed in experiments even at a small distance from the nozzle cut. The predicted data are compared with experimental ones obtained at theexperimental setup.

Advanced Packaging Technology for Novel 1-dimensional and 2-dimensional VCSEL Arrays

Abstract In this paper we present an optimized manufacturing technique for special long-wavelength 1-dimensional and 2-dimensional Vertical Cavity Surface Emitting Laser Diode (VCSEL) arrays with focus on die bonding and a special wire bonding process as well as additional possibilities to make the manufacturing more productive and to increase the product quality, reliability, and life time. VCSEL arrays have a very broad application potential. Objective of this paper is the development of an assembly technology for long-wavelength VCSEL arrays with high positioning accuracy for automated production with high total yield, using gold-based conductive glue (because silver migration is a concern) securing high yield and extremely high reliability and lifetime. Due to special customer requirements, a final thickness of the conductive glue of 35 micron with low standard deviation is necessary. For highest reliability, gold wire bonding of the top side contact of the VCSEL to a silicon substrate with gold metallization has been a customer requirement. With the described technique we develop and produce customer specific products with dedicated wavelength, performance, and packaging options. Bases on our findings, very flexible and scalable solutions are possible, matching many different applications. Finally, we will present an overview of our results on the physical and electro-optical characterization of the VCSEL devices. This yielded a very productive manufacturing technique, meeting the requirements mentioned above. Special design features of the VCSEL ensure that the relatively high thermal resistance of the cured conductive glue layer does not impair the electro-optical properties or the lifetime of the VCSELs. For the interconnection of the top side contact we used gold wire with 20 microns diameter, using ball-wedge, Stand-Off Stich Bond process with special loop geometry, required by the customer. Due to the properties of the semiconductor material of the VCSELs a low bonding temperature is required, enabled by our special wire bonding process. Gold wire bonding delivered excellent results, by far exceeding the customer specification. The optical spectrum of the VCSELs and other measurements indicate that the assembly processes do not harm the laser diodes or their electro-optical properties. All customer requirements for the 1-dimensional and 2-dimensional VCSEL arrays have been met. The electro-optical and burn-in data furnished proof of the quality of the engineered assembly technology. The technologies developed for low current as well as high current laser arrays will enable new devices for a huge amount of new applications because of the novel manufacturing processes as well as innovative packaging of the VCSEL arrays.

Ambient particulate matter levels and health profile in residents of Choba and Mgbuoba areas of Rivers State: A cross-sectional study

ABSTRACT The study investigated the health profile of individuals exposed to particulate matter (Black) soot in Choba and Mgbuoba localities of Port Harcourt. The analysis was executed with the aid of 100 respondents (50 from Choba and 50 from Mgbuoba). A structured questionnaire with the outlined elements was utilized during data collection for the study: manner of living, type of occupation, environmental exposure, known health issues, fitness and cleanliness, and Key Informant Interviews (KII) were exploited to gain pertinent data from health professionals. A hand-held Kestrel weather tracker was employed to ascertain the wind speed, temperature, and relative humidity of the study areas while A Met One Instrument, Inc. Aerosol Mass Monitor Model GT–531 was utilized to estimate total suspended particulates. Biochemical parameters such as lipid profile, renal markers, and liver markers activities were analyzed from blood samples obtained from the subjects using spectrophotometric methods. The air quality profile of Mgbuoba showed significant (p < .05) increment in total suspended particulate matter, total suspended particulate matter (TSPM), particulate matter that is 10 microns in diameter or less (PM10), and particulate matter that is 2.5 microns in diameter or less (PM2.5) from 6 a.m. to 8 a.m. compared with Choba. The increment in Total suspended particulate matter, PM10, and PM2.5 levels were beyond the 24-hour PM10 and PM2.5 recommended level by the World Health Organization (WHO). The alanine transaminase (ALT) and low density lipoproptein (LDL) levels of Choba and Mgbuoba residents were beyond the reference limits set by the Medical Council of Canada. The study showed that residents in Mgbuoba in Port Harcourt may be more at risk and have higher vulnerability to the undesirable outcomes associated with exposures to these air contaminants. A rising and worrisome trend in respiratory and related conditions among less mobile residents call for emergency response to emission of black soot in the area. Implications: The study investigated the health profile of individuals exposed to particulate matter (Black) soot in Choba and Mgbuoba localities of Port Harcourt. This outcome clearly shows that these air pollutants are higher in concentrations early in the morning and their concentrations decreased as the day went by. Therefore, by implication, the residents in these areas may be at high risk of exposure to these air pollutants from 6 a.m. to 8 a.m. The present study has demonstrated that these air pollutants are more prominent very early in the mornings and variations in meteorological conditions at a particular time, and anthropogenic activities might have contributed to the elevations in the concentration of TSPM, PM10, and PM2.5 in Choba and Mgbuoba.

Dielectric and piezoelectric properties of PLZT x/40/60 (x = 5; 12) ceramics

The paper presents the results of studies of the structure, piezoelectric and dielectric properties of lead zirconate-titanate ceramics modified with lanthanum of various concentrations (PLZT). It was found that with an increase in the La content, the grain size and the average domain size increase. The PLZT 12/40/60 samples contain both labyrinth-like and periodic domains, as well as different lateral sizes from several hundred nanometers to 3 microns in diameter. It was found that the piezoelectric response signal increases with increasing domain sizes in samples with a high lanthanum content. The fact of the existence of areas on surface of PLZT x/40/60 ceramics having an internal displacement field is established, as evidenced by the asymmetry of the remnant piezoelectric hysteresis loops along the voltage axis. In the samples PLZT 5/40/60 and PLZT 12/40/60, a significant dispersion of the permittivity ε(f) and a maximum of the tangent of the dielectric loss angle were observed in the frequency range from 105 to 106 Hz. This is due to the presence of ionic relaxation polarization, as is the case in ionic dielectrics. It is established that the value of the dielectric constant increases markedly with increasing La, which confirms the occurrence of a rigid unipolar state in the PLZT 12/40/60 ceramic grains. In the samples under study, an increase in the tangent of the dielectric loss angle is observed at low frequencies of the measuring field, which is associated with the contribution of conductivity to tg δ. The dependences of the dielectric loss factor ε” on the dielectric permittivity ε’are constructed. They have the form of Cole-Cole diagrams, which indicates the presence of a relaxation time spectrum, while it was found that the spectrum width in PLZT 5/40/60 samples is about two times less than in PLZT 12/40/60 samples.

How to Avoid the Detachment of Threads of Varnish during Production, through Cutting and Drawing, in the Manufacture of Lids with a 'Twist-Off' Mechanism Used for the Closure of Glass Containers.

The lids of glass containers which have a ‘twist-off’ mechanism are manufactured from tinplate through a process of cutting and drawing. Previously, the tinplate was protected with a double layer of a certain epoxy-phenolic varnish. During cutting, the detachment of threads of varnish is produced, and these may reach more than 150 microns in diameter. These threads stick to the equipment, thus hindering the shaping process. After manufacturing thousands of lids, stops must inevitably be made in production in order to clean machinery. Through the application of a fractioned design of experiment (DoE) application, carried out on an industrial scale, the effect of a number of factors on the detachment of threads of varnish was studied. Some to these factors refer to coating, others to the substratum and others to the process of cutting and drawing. It is concluded that the detachment is greater in the disk areas which are parallel to the forward direction of the production line. This problem could be substantially reduced, and even eliminated, if the direction of the rolling of the sheet metal were perpendicular to that of the forward direction of the production line, if the blank-holder is situated at 4 bar, if the time between the curing process and cutting is no more than 3threedays, if the clearance in the cutting is situated at 0.06 mm, and if the grammage of the varnish and the grammage of the layer of tin are increased.

Lepidoptera demonstrate the relevance of Murray\u2019s Law to circulatory systems with tidal flow

BackgroundMurray’s Law, which describes the branching architecture of bifurcating tubes, predicts the morphology of vessels in many amniotes and plants. Here, we use insects to explore the universality of Murray’s Law and to evaluate its predictive power for the wing venation of Lepidoptera, one of the most diverse insect orders. Lepidoptera are particularly relevant to the universality of Murray’s Law because their wing veins have tidal, or oscillatory, flow of air and hemolymph. We examined over one thousand wings representing 667 species of Lepidoptera.ResultsWe found that veins with a diameter above approximately 50 microns conform to Murray’s Law, with veins below 50 microns in diameter becoming less and less likely to conform to Murray’s Law as they narrow. The minute veins that are most likely to deviate from Murray’s Law are also the most likely to have atrophied, which prevents efficient fluid transport regardless of branching architecture. However, the veins of many taxa continue to branch distally to the areas where they atrophied, and these too conform to Murray’s Law at larger diameters (e.g., Sesiidae).ConclusionsThis finding suggests that conformity to Murray’s Law in larger taxa may reflect requirements for structural support as much as fluid transport, or may indicate that selective pressures for fluid transport are stronger during the pupal stage—during wing development prior to vein atrophy—than the adult stage. Our results increase the taxonomic scope of Murray’s Law and provide greater clarity about the relevance of body size.

Imaging of Organic Samples with Megaelectron Volt Time-of-Flight Secondary Ion Mass Spectrometry Capillary Microprobe.

Time-of-flight Secondary Ion Mass Spectrometry (TOF SIMS) with MeV primary ions offers a fine balance between secondary ion yield for molecules in the mass range from 100 to 1000 Da and beam spot size, both of which are critical for imaging applications of organic samples. Using conically shaped glass capillaries with an exit diameter of a few micrometers, a high energy heavy primary beam can be collimated to less than 10 μm. In this work, imaging capabilities of such a setup are presented for some organic samples (leucine-evaporated mesh, fly wing section, ink deposited on paper). Lateral resolution measurement and molecular distributions of selected mass peaks are shown. The negative influence of the beam halo, an unavoidable characteristic of primary beam collimation with a conical capillary, is also discussed. A new start trigger for TOF measurements based on the detection of secondary electrons released by the primary ion is presented. This method is applicable for a continuous primary ion beam, and for thick targets that are not transparent to the primary ion beam. The solution preserves the good mass resolution of the thin target setup, where the detection of primary ions with a PIN diode is used for a start trigger, reduces the background, and enables a wide range of samples to be analyzed.

BLASTOCYST "PUMPING" IS A DETRIMENTAL FEATURE PREDICTING IMPLANTATION FAILURE: HIGHLY ACCURATE ASSESSMENT BY COMPUTER VISION ANALYSIS OF TIME-LAPSE VIDEOS

To determine for the first time, whether "pumping" or "weak contraction," defined as blastocoelic contraction by more than 8 microns in diameter, is associated with poor implantation rates, independent of other morphokinetic features. We analyzed 148,441 images from time-lapse sequences of 317 expanded blastocysts, chosen for transfer, with known implantation data. Using a computer vision algorithm, we were able to measure the blastocyst diameter, approximated to a best-fit circle, in steps of 8 microns. We defined a "pumping event" or a "weak contraction" when the blastocyst diameter was more than 8 microns smaller in diameter when compared to its image taken 40 minutes earlier. We further defined a "major pumping event," when the contraction in blastocyst diameter was greater than 16 microns, vs a “minor pumping event” where it was greater than 8 but no more than 16 microns. We also defined an "early pumping event" when it occurred as the blastocyst was up to 140 microns in diameter vs a “late pumping event” where the blastocyst was over 140 microns. The extent, number of pumping events, and the stage of blastulation at which it occurred were measured and compared to the embryos’ known implantation outcomes. Of the 317 blastocysts, 188 (59.3%) successfully implanted. Of the 188 blastocysts that implanted, early pumping was noted in 27 (14%) blastocysts, for a total of 73 events, at average ± SD 110.7±4.2 hours. Early pumping events occurred in 22 (17%) of the 129 blastocysts that failed to implant with overall 80 events at average ± SD 112.0±4.8 hours. Major pumping events occurred 25 times in 14 (7%) blastocysts that implanted at average ± SD 110.5±7.7 hours vs. 38 events in 18 (14%) blastocysts that failed to implant, at average ± SD 111.7±4.6 hours. Major pumping events were significantly correlated with implantation failure (OR 1.87, P=0.03, for at least one major pumping event, OR 2.42, P=0.04 for at least two major pumping events). Multiple early pumping events significantly correlated with implantation failure (OR 2.07, P=0.02, for at least three early pumping events, OR 2.55, P=0.02, for at least four early pumping events). Weak blastocyst contractions can be defined and accurately measured using computer vision algorithms. These algorithms allowed us to measure changes in blastocyst diameter with unprecedented accuracy of 8 microns. Multiple "early" or "major" pumping events were found to be uncommon, but when they occur, they are strongly predictive of implantation failure. Therefore, blastocysts should be preferably deselected if they exhibit this behavior.

Regulation of Parvalbumin Interactome in the Perilesional Cortex after Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) causes 10–20% of structural epilepsy, with seizures typically originating in the cortex. Alterations in the neuronal microcircuits in the cortical epileptogenic zone, however, are poorly understood. Here, we assessed TBI-induced changes in perisomatic gamma aminobutyric acid (GABA)-ergic innervation in the perilesional cortex. We hypothesized that TBI will damage parvalbumin (PV)-immunoreactive inhibitory neurons and induce regulation of the associated GABAergic molecular interactome. TBI was induced in adult male Sprague-Dawley rats by lateral fluid-percussion injury. At 1-month post-TBI, the number of PV-positive somata was plotted on unfolded cortical maps and the distribution and density of immunopositive terminals analyzed. Qualitative analysis revealed either patchy microlesions of several hundred micrometers in diameter or diffuse neuronal loss. Quantitative analysis demonstrated a reduction in the number of PV-positive interneurons in patches down to 0% of that in sham-operated controls in the perilesional cortex. In the majority of patches, the cell numbers ranged from 71% to 90% that of the controls. The loss of PV-positive somata was accompanied by decreased axonal labeling. In situ hybridization revealed downregulated PV mRNA expression in the perilesional cortex. Gene Set Enrichment Analysis indicated a robustly downregulated expression profile of PV-related genes, which was confirmed by quantitative reverse transcriptase polymerase chain reaction. Specifically, we found that genes encoding postsynaptic GABA-A receptor genes, Gabrg2 and Gabrd, were downregulated in TBI animals compared with controls. Our data suggests that patchy reduction in PV-positive perisomatic inhibitory innervation contributes to the development of focal cortical inhibitory deficit after TBI.

Comparitive Study of Human Lymph Nodes

All the lymph nodes observed were typically bean shaped irrespective of their age or sex. The cervical lymph nodes were the largest of all the four groups in size. The mean maximum short axis axial diameter was 7.19mm (Range 5.67mm - 8.12mm). The mesentericl lymph nodes were the smallest of all the four groups in size. The mean maximum short axis axial diameter was 3.89mm (Range 2.7mm -6.lmm). The lymph nodes showed well defined deep cortical regions often containing large lymphoblasts and prominent endothelial cells in small blood vessels. The thickness of the deep cortex was however reduced when compared to its foetal counterpart. The mean thickness of the deep cortical region was 423 microns. To reconfirm the age related involution of the paracortical region, the mesenteric lymph nodes were observed. In sharp· distinction, axillary lymph nodes showed fewer germinal centres which were relatively smaller in size.Mean actual diameter of the germinal centre was77 microns also had had fewer and smaller germinal centres. Mean actual diameter of the germinal centre was 68 microns.

Combined Effects of Air pollutants on Gestational Diabetes Mellitus: a Prospective Cohort Study

BACKGROUND AND AIM: Maternal exposure to air pollutants increases the risk of gestational diabetes mellitus (GDM). Still, the associations between exposure to air pollutants before pregnancy and GDM are unclear, as well as their combined effects. We aimed to identify exposure to air pollutants before pregnancy associated with GDM risk and to determine any combined effect of these components. METHODS: This study included 20113 participants from the Born in Guangzhou Cohort Study (BIGCS). The inverse distance-weighted models were used to estimated individual air pollutant exposure, namely ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter less than 10 microns in diameter (PM10), and less than 2.5 microns in diameter (PM2.5). We used generalized estimating equations to examine the stage-specific associations of air pollutants with the risk of GDM. RESULTS:Of the 20113 participants, 3440 women were diagnosed with GDM. In adjusted models, O3 exposures in 3-6 months before pregnancy and in the first trimester were significantly positively associated with the risk of GDM, adjusted relative risks (95% confident intervals) [RRs (95%CI)] were 1.05 (1.00, 1.09) and 1.05 (1.01, 1.10), respectively. SO2 concentrations in 3-6 months before pregnancy and PM10 concentrations in the first trimester were related to an increased risk of GDM, RRs (95% CI) were 1.21 (1.04, 1.40) and 1.07 (1.02, 1.12), respectively. The RR in groups with high concentrations of two air pollutants was higher than that in groups with one high concentration pollutant only. CONCLUSIONS:This large study provided evidence on the positive association between exposure to air pollutants six months before pregnancy period to the first trimester and the risk of GDM. The effects of combined exposure to multiple air pollutants were higher than that of single exposure. These findings suggested that public health strategies were needed to reduce the adverse effects of air pollution exposure on pregnant women. KEYWORDS: air pollution, gestational diabetes mellitus, maternal exposure, cohort study

Early Life Exposure to Ambient Air Pollutants is Associated with Decreased Cognitive Development in Hispanic Infants from Southern California

BACKGROUND AND AIM: Previous research has established an association between postnatal ambient air pollution (AAP) exposure and cognitive development in preschoolers and school-aged children. However, this association has not been examined during infancy, a critical neurodevelopmental window. The purpose of this study was to explore relationships between postnatal AAP exposure and cognitive development in infants. METHODS: This study examined 118 Hispanic mother-infant pairs from the longitudinal Mother’s Milk Study in Southern California. Average individual residential exposure to AAP, including nitrogen dioxide (NO2) and particulate matter smaller than 2.5 and 10 microns in diameter (PM2.5 and PM10 respectively), in the first month of life was estimated from central site monitors. Infant cognitive outcomes at 24-months were measured using the Bailey-III Scales of Infant and Toddler Development. Multivariate linear regression was used to examine relationships between postnatal AAP exposure and age scaled cognitive scores, adjusting for socioeconomic status, breastfeeding frequency, time of delivery (early/late/on-time) as a proxy for gestational age, pre-pregnancy BMI, birthweight, and sex. Effects are reported for each standard deviation increase in exposure. RESULTS:NO2 was negatively associated with fine motor score (β=-0.55, p=0.006), motor score (β=-0.90, p =0.007), and cognitive score (β=-0.55, p=0.01). PM2.5 and PM10 were negatively associated with social emotional scores (β=-0.77, p=0.009 and β=-0.66, p=0.01 respectively). The association between NO2 and cognitive score varied by infant sex (p-interaction = 0.046), where NO2 was negatively associated with cognitive score among females (β=-0.16, p=0.0006) but not males (β=-0.01, p=0.81). CONCLUSIONS:Higher postnatal exposure to AAP in the first month of life was inversely associated with scaled motor, cognitive, and social-emotional scores at 24-months of age. Sex-specific findings for scaled cognitive score may suggest differential impacts of AAP exposure among females. These results indicate that AAP may negatively impact neurodevelopment in early life. KEYWORDS: Air Pollution, Neurodevelopmental Outcomes, Multi-pollutant, Environmental Disparities, Short-term Exposure

Short-term exposure to airborne particulate matter and COVID-19 infection in South Korea

BACKGROUND AND AIM: Coronavirus disease 2019 (COVID-19) has become a global public health problem. Previous studies have indicated that COVID-19 infection can occur through airborne transmission, and atmospheric particulate matter may favor the spread of the virus. This study aimed to explore the relationship between daily particulate matter ≤ 2.5 or 10 micrometers in diameter (PM2.5 or PM10) and daily COVID-19 confirmed cases in South Korea. METHODS: We obtained daily confirmed cases, PM concentrations, and meteorology in South Korea from the first occurrence on February 24 through December 31 in 2020. Using generalized additive model, we estimated relative risks (RRs) of COVID-19 new cases for a 10µg/m3 increase in PM averaged over the previous 1, 3, 5, 7, 10, 14, and 21 days after adjusting for a temporal trend, meteorology, new confirmed cases on the previous day, and day of week. Non-linear associations of the temporal trend and meteorology with new cases were assessed by using regression spline. In particular, we applied 35 degrees of freedom (df) to the temporal trend, which is larger than as used in previous studies to account for relatively short-term changes in new cases derived by people’s activity patterns. RESULTS:Although there was no evidence of the association of daily confirmed cases with recent exposures to PM2.5, we found the positive association with extended exposure for the previous 14 and 21 days (RR=1.13, 95% CI=1.01-1.27; 1.17, 1.04-1.3, respectively). These patterns were similar for PM10 (1.03, 0.95-1.12; 1.1, 1.00-1.2, respectively). The findings were also consistent with more or less adjustment for time in our sensitivity analysis. CONCLUSIONS:Our findings suggested that airborne particulate matter can accelerate risk of COVID-19 transmission in two or three weeks. Further studies should account for other transmission-related characteristics to confirm the association. KEYWORDS: Air pollution, short-term exposure, COVID-19 incidence

The Association Between PM2.5 and Blood Pressure in Indonesia

BACKGROUND AND AIM: Indonesia faces significant air quality issues due to peatland fires associated with agricultural land management and rapid urbanization. Limited prior research has estimated the episodic shock of intense fires on morbidity and mortality in Indonesia but has largely ignored the impact of poor air quality on biomarkers of chronic disease risk. We conducted a cross-sectional study of the association between particulate matter less than 2.5 microns in diameter (PM₂.₅) and blood pressure. METHODS: Blood pressure was obtained from the fifth wave of the Indonesian Family Life Survey (IFLS5), fielded in late 2014 and early 2015. The IFLS is an ongoing population-based socioeconomic and health survey. We used a global chemical transport model, GEOS-Chem version 12.8.2, to simulate daily PM₂.₅ concentrations at 0.5° x 0.625° resolution across the IFLS domain. GEOS-Chem, a three-dimensional atmospheric composition model, was used to assign PM₂.₅ exposure based on each participant’s kabupaten, or district, of residence. We assessed the association between PM₂.₅ and blood pressure, using mixed effects models with random intercepts for kabupaten and household and adjusted for age, sex, smoking status, BMI, hypertension medication, education, subjective socioeconomic status, and seasonality. RESULTS:For each 10 µg/m³ increase in PM₂.₅ in the month before the clinical exam, we find a 0.14% (95% CI: -0.01, 0.28) increase in diastolic blood pressure in adults, with a greater association seen in participants age 65 and over (0.6%, 95% CI: 0.03, 1.17). For the same exposure metric, there was a 0.8% (95% CI: 0.18, 1.41) increase in systolic blood pressure in participants 65 and older. CONCLUSIONS:To our knowledge, this is the first study to provide evidence for an association between PM₂.₅ and blood pressure in Indonesia. If this association is causal, the health burden of air quality within Indonesia may be severely underestimated. KEYWORDS: air pollution, particulate matter, wildfires, cardiovascular diseases

Ambient Air Pollution (PM2.5 &amp; O3) in Relation to ADHD in NYC Children Age 3-13 Years

BACKGROUND AND AIM: Recent studies have investigated the relationship between air pollution and Attention Deficit/Hyperactivity Disorder (ADHD) with inconsistent results. The specific causes of ADHD remain unknown; however, there is biologic plausibility for etiologic mechanisms linking air pollution exposure and neurodevelopmental outcomes, such as ADHD. METHODS: We included 5,032 children ages 3-13 years from the 2017 New York City KIDS survey on children’s health provided by New York City Department of Health & Mental Hygiene, of which 303 had a parent report of ADHD diagnosed by a mental health professional. Using the child’s date of birth and residential neighborhood (sub-borough) during the survey, we linked to daily air pollution data from U.S. Environmental Protection Agency fused air quality using surface downscaling (FAQSD) model, focusing on particulate matter 2.5 micrometers in diameter (PM2.5) and ozone (O3). We estimated odds ratios (aOR) adjusting for child’s sex, child’s race/ethnicity, highest parental education, household income, and indoor tobacco use. RESULTS:One-year postnatal PM2.5 and O3 mean, standard deviations and correlation: 11.1±1.5 (ug/m3); 66.3±4.4 (ppb); -0.67 correlation. ADHD was associated with PM2.5, with aOR and 95% confidence interval (CI) per ug/m3 increase in PM2.5: prenatal=1.13(1.01,1.27); postnatal=1.19(1.07,1.31); combined prenatal and postnatal=1.18(1.07,1.31). In contrast, ozone exhibited inverse associations, with aOR and 95%CI per ppb increase in O3 exposures for prenatal=0.92 (0.87,0.98), postnatal=0.85(0.78,0.94), and combined prenatal and postnatal=0.87(0.79,0.94). CONCLUSIONS:Despite air pollution measurement error resulting from geographic aggregation at the neighborhood-level, we observed links between PM2.5 and ADHD that align with prior studies. Our observed inverse associations between O3 and ADHD are unlikely to reflect beneficial effects of ozone given its known harmful impacts and may be artifacts of the negative correlation between ozone and PM2.5. These results provide further support for the adverse impact of air pollutants such as PM2.5 during pregnancy and infancy on the risk for development of ADHD. KEYWORDS: ADHD, Air Pollution, Children's Environmental Health, Neurodevelopmental Outcomes, Ozone, Particulate Matter

Stem Cells to the Rescue: Development and Application of Cell-Based Therapy for Microvascular Repair

The microcirculation includes an invisible network of micro-vessels that are up to a few hundred microns in diameter [...].

A highly efficient cloth facemask design

Wearing masks and face coverings helps reduce transmission of respiratory diseases. Much prior research on mask filtration efficiency has focused on fabric type, with less consideration given to mask design and shape. Here, we present evidence that increasing the mouth-mask separation distance engenders an increase in the mask-fabric filtration efficiency toward expiratory aerosols emitted via vocalization, which we attribute to a decrease in the expiratory jet velocity and expansion of the breath-mask contact area. We further assess the performance of a new reusable cloth facemask design, originally made for, but not exclusive to, professional singers and having a large mouth-mask separation distance. With proper fitting, these masks achieve overall filtering efficiencies of >93% for both exhaled expiratory aerosols >0.5 microns in diameter from singing and speaking and for inhaled ambient aerosols, better than surgical masks and approaching N95 respirators. Air exchange between the mask deadspace and the ambient environment limits the extent of CO2 buildup and in inhaled air and maintains O2 levels near ambient. The mask design also provides for less inhibited mouth and jaw movement and lower relative humidity, suggesting it may provide a more palatable, high-efficiency alternative to medical-grade masks for the public.Copyright © 2021 American Association for Aerosol Research

A cluster randomised trial of cookstove interventions to improve infant health in Ghana

IntroductionHousehold air pollution from solid fuel combustion for cooking and heating is a leading cause of childhood morbidity and mortality worldwide. We hypothesised that clean cooking interventions delivered during pregnancy...

Microporosity quantification using confocal microscopy

ABSTRACTIn carbonate rocks, pore diameters range in size over at least nine orders of magnitude, from submicrometer-scale voids to km-scale caves. This study is focused on micropores, which are defined as pore bodies with diameter ≤ 10 micrometers. Corresponding pore throats are generally ≤ 1 micrometer in diameter. To visualize and quantify microporosity, geologists commonly use pore casts, transmitted-light petrography, and scanning electron microscopy. Shortfalls exist in all of these techniques. Laser scanning confocal microscopy, a relatively new approach, provides a step change in our ability to image and quantify microporosity in carbonate rocks.Laser scanning confocal microscopy provides high-resolution (0.2-micrometers/pixel) images of micropores. Such pores are generally obscure or invisible using conventional petrography. In practice, confocal microscopy is applied to polished rock chips or thin sections that have been vacuum-pressure impregnated with epoxy. The laser light source interacts with fluorescent dye within the epoxy. Emitted fluorescent light, recorded using point-by-point illumination, indicates the physical location of pores. A pinhole, placed in front of the detector, eliminates out-of-focus light. Because each measurement is a single point, confocal microscopes scan along grids of parallel lines to provide optical images of planes at specified depths within the sample.Confocal microscopy is used to generate 2D and 3D images of pore bodies and throats. Results can be compared to laboratory-measured petrophysical properties, such as pore-throat diameters from mercury injection capillary pressure (MICP) data. Now, for the first time, we can compute pore-body to pore-throat size ratios without pore casts. These ratios are important, because they can be related to mercury recovery factors from imbibition MICP experiments.

Rapid mechanical stimulation of inner-ear hair cells by photonic pressure.

Hair cells, the receptors of the inner ear, detect sounds by transducing mechanical vibrations into electrical signals. From the top surface of each hair cell protrudes a mechanical antenna, the hair bundle, which the cell uses to detect and amplify auditory stimuli, thus sharpening frequency selectivity and providing a broad dynamic range. Current methods for mechanically stimulating hair bundles are too slow to encompass the frequency range of mammalian hearing and are plagued by inconsistencies. To overcome these challenges, we have developed a method to move individual hair bundles with photonic force. This technique uses an optical fiber whose tip is tapered to a diameter of a few micrometers and endowed with a ball lens to minimize divergence of the light beam. Here we describe the fabrication, characterization, and application of this optical system and demonstrate the rapid application of photonic force to vestibular and cochlear hair cells.