Plot of % Transmittance vs. wavelength for the 3 sun filters used in this study.

<p>Neutral density filters were used to attenuate the light to <1% of original value to provide “on-scale” measurements.</p

Evaluation of Accuracy.

<p><i>Left</i> – Plot of accepted transmittance of a series of optical filters <i>vs</i>. smart phone measured transmittance using the sun (red) and a lamp (blue) as light source. The accepted filter transmittances were determined by either product literature or by using a spectrophotometer. The solid best-fit line was determined by orthogonal distance regression. The slope of the line is close to unity and the intercept indistinguishable from zero indicating good agreement between the measurements. <i>Right</i> – Histogram of differences between smart phone measured and accepted transmittances for sun data. A slight positive bias is reflected in the data. The calculated standard deviation (<i>s</i>) of differences between measurements was 0.058, yielding a 2<i>s</i> uncertainty of ±0.116 or 11.6% T.</p

Optical depths measured with smartphone sun photometer and reference device.

<p>Panel (A) – Optical depths at Lubbock, TX from 9:00 AM to 6:00 PM on September 1 2013. Measurements were made with both smart phone sun photometer and reference method on blue, green and yellow channels. On this day, optical depths shifted up and down because of the existence of clouds in the sky as seen in the photographs. (B) – Comparison of transmittance measurements using smartphone and reference method. The y-axis shows atmospheric transmittance measured by the smartphone while x-axis shows transmittance measured by reference method. Small dots illustrate all measurements made with the two devices. Larger square markers are median values for different bins. Best-fit lines were determined by orthogonal distance regression from medians.</p

Monitoring atmospheric optical depth and Angstrom exponent at Lubbock, TX during the afternoon of September 17 2012 using the smart phone sun photometer on the blue, green, and yellow channels.

<p>This afternoon featured a very thin, high-altitude stratus cloud layer that periodically blocked the sun and increased optical depth. This effect is particularly noticeable near 4:00 PM local time when a rapid and large increase in optical depth was observed. This change was accompanied by a reduction in Angstrom exponent by approx. 1 unit which suggests larger particles contribute to the increase in optical attenuation. Angstrom exponents reported consider the effect of both gases and particles. No measurements are made on the “visible” channel – this is only included to provide the reader with a visual reference.</p

Portable, Ambient PM_2.5 Sensor for Human and/or Animal Exposure Studies

<p>A field-portable device for logging PM_2.5 mass concentration data has been developed. The device combines the Arduino microprocessor with an SD card, a Sharp DN7C3CA006 optical dust monitor, and 10,000-mAh battery. The dust sensor uses a virtual impactor to size select particles <2.5 microns prior to illuminating the selected fraction with an LED. The LED is triggered by a circuit controlled with the Arduino. Nephelometric detection at 120° referenced to incidence is used. The voltage signal reported by the dust sensor is converted to PM_2.5 mass through calibration onboard the Arduino. Data points can be saved to the SD card as rapidly as 0.3 s, although averaging signals over 60 s produced more optimal detection limits. For a 60 s average, the PM_2.5 mass limit of detection was 9 µg m⁻³, indicating that the sensor will be useful for monitoring human exposure to fine particles. Portable exposure monitoring has been demonstrated with the sensing platform as several individuals carried the device with them during daily activities in Lubbock, TX and Atlanta, GA. For this group of test subjects, values of PM_2.5 exposure varied from 0 to 1000 µg m⁻³ during the sampling periods. It was observed that, by far, the highest levels of PM_2.5 occur during periods of cooking, or being near cooking operations. Other periods of high PM_2.5 occurred during ground transportation, use of personal care products, vacuuming, and visiting restrooms. When hourly personal exposure data were correlated with hourly average PM_2.5 for outdoor air for the Atlanta data set, a very weak correlation was found (<i>R</i>² = 0.026). Only two out of eight sampling periods did the personal monitoring estimate of exposure agree with that predicted by outdoor monitoring to within 15%. Personal exposure was often affected by circumstantial, short-term, high exposure events that are difficult to model or predict effectively. The short-term exposure events generally cause true exposure to be higher than that predicted by using outdoor ambient PM_2.5 to generate estimates. This finding complicates interpretation of epidemiological studies that find links between ambient outdoor PM_2.5 levels and human health, while it buttresses the case for using personal ambient monitors.</p

Remote Sensing of Atmospheric Optical Depth Using a Smartphone Sun Photometer

<div><p>In recent years, smart phones have been explored for making a variety of mobile measurements. Smart phones feature many advanced sensors such as cameras, GPS capability, and accelerometers within a handheld device that is portable, inexpensive, and consistently located with an end user. In this work, a smartphone was used as a sun photometer for the remote sensing of atmospheric optical depth. The top-of-the-atmosphere (TOA) irradiance was estimated through the construction of Langley plots on days when the sky was cloudless and clear. Changes in optical depth were monitored on a different day when clouds intermittently blocked the sun. The device demonstrated a measurement precision of 1.2% relative standard deviation for replicate photograph measurements (38 trials, 134 datum). However, when the accuracy of the method was assessed through using optical filters of known transmittance, a more substantial uncertainty was apparent in the data. Roughly 95% of replicate smart phone measured transmittances are expected to lie within ±11.6% of the true transmittance value. This uncertainty in transmission corresponds to an optical depth of approx. ±0.12–0.13 suggesting the smartphone sun photometer would be useful only in polluted areas that experience significant optical depths. The device can be used as a tool in the classroom to present how aerosols and gases effect atmospheric transmission. If improvements in measurement precision can be achieved, future work may allow monitoring networks to be developed in which citizen scientists submit acquired data from a variety of locations.</p></div

Langley Plots (ln signal counts <i>vs</i>. air mass) for the blue (A), green (B), and yellow (C) sun filters.

<p>The slope of the best-fit lines represents optical loss per unit air mass while the intercept describes the signal expected at the top-of-the-atmosphere (TOA). Best-fit lines were determined by orthogonal distance regression.</p

Data_Sheet_1_Characterization of the oral microbiome and gut microbiome of dental caries and extrinsic black stain in preschool children.PDF

IntroductionA lower prevalence of dental caries (hereafter termed “caries”) has been observed in children with dental extrinsic black stain (EBS).MethodsWe investigated the epidemiologic characterization of EBS and explored the possible role of the oral microbiome (OM) and gut microbiome (GM) in EBS formation and caries prevention. In an epidemiologic survey, 2,675 children aged 3–6 years were included. Thirty-eight of these children (7 children had both caries and EBS, 10 had EBS only, 11 had caries only, and 10 were healthy children) were recruited for 16S rRNA sequencing and collection of samples of supragingival plaque and feces. Collected plaque samples were divided into four groups: BCP (EBS+, caries+), BP (EBS+, caries−), CP (EBS−, caries+), and P (EBS−, caries−). Fecal samples were also divided into four groups: BCF (EBS+, caries+), BF (EBS+, caries−), CF (EBS−, caries+), and F (EBS−, caries−).ResultsEBS was observed in 12.10% of this population. Children with EBS had a significantly reduced prevalence of caries and a lower mean value of decayed–missing–filled teeth (dmft; p < 0.01). According to analyses of dental plaque, the P group had the most complex microbiome. The BCP group exhibited greater operational taxonomic unit (OTU) richness but a reduced evenness compared with the BP group, and the CP group showed greater OTU richness than the BP group. At the genus level, higher abundance of Actinomyces and Cardiobacterium species was observed in the BCP group. Higher abundance of Lautropia and Pesudopropionibacteriumin species was observed in the BP group compared with P and CP groups, respectively (p < 0.05). Veillonella species were significantly more common in P and CP groups than in BP groups, whereas Porphyromonas and Fusobacterium species were more common in the CP group (p < 0.05). With regard to the GM, the CF group exhibited greater OTU diversity than the BF group. The GM in the BCF group exhibited the most complex relationships across all fecal groups. GM groups could be distinguished by various unique biomarkers, such as Escherichia and Shigella species in the BCF group, Agathobacter and Ruminococcus species in the CF group, Lactobacillus species in the BF group, and Roseburia species in the F group. Our results suggest that EBS is a possible protective factor against early-childhood caries. Dental plaque and the GM may be relevant to EBS in primary dentition.</p

Understanding the Electrochemical Properties of Li-Rich Cathode Materials from First-Principles Calculations

The lithium-rich layered oxide materials (LLOs) have attracted much attention as candidates for the next generation of LIBs because of their high voltage and high capacity, which are still poorly understood. In this study, the origin of high voltage and high capacity of LLOs has been comprehensively investigated through first-principles calculations. It is revealed that due to the asymmetric oxidation behavior of Li₂MnO₃/LiMO₂ interface, the transition-metal–oxygen (TMO) layer of Li₂MnO₃ phase in Li-rich materials gains more electrons from Li layer than that in pure Li₂MnO₃, which results in the stronger hybrid between Mn-3d and O-2p states enhancing the activity of Mn in Li₂MnO₃. Moreover, the deintercalated Li-rich models possess smaller spacing than pure LiMO₂, which reflects stronger electrostatic interaction between TMO and Li layers. The two factors are both beneficial to the high voltage of the Li-rich materials. However, the asymmetric interface also results in the increase of electronic states of transition metal atoms near the Femi level, which changes the oxidized sequence of Ni²⁺/Ni⁴⁺ and Co³⁺/Co⁴⁺, and reduces the participation of oxygen in the redox process. As a result, the voltage and reversible capacity of Li-rich materials are significantly enhanced compared with that of pure LiMO₂

Microscopic morphology of soil under different treatments at 200 μm scale.

(a is for Control treatment; b is for Cynodon dactylon; c is for Medicago; d is for Lolium perenne).</p