Carbon Scatter 2015.epub
The scanning electron microscope is used in various fields to go beyond diffraction limits of the optical microscope. However, the electron pathway should be conducted in a vacuum so as not to scatter electrons. The pretreatment of the sample is needed for use in the vacuum. To directly observe large and fully hydrophilic samples without pretreatment, the atmospheric scanning electron microscope (ASEM) is needed. We developed an electron filter unit and an electron detector unit for implementation of the ASEM. The key of the electron filter unit is that electrons are transmitted while air molecules remain untransmitted through the unit. The electron detector unit collected the backscattered electrons. We conducted experiments using the selected materials with Havar foil, carbon film and SiN film.
Carbon Scatter 2015.epub
Conclusions: Considerations of the environmental impact of foods need to be linked to concerns about nutrient density and health. The point at which the higher carbon footprint of some nutrient-dense foods is offset by their higher nutritional value is a priority area for additional research.
While MRI reveals anatomical details, it lacks molecular information specific to glioma growth and metabolism. As an alternative, there is positron emission tomography (PET), a functional imaging technique that enables highly sensitive measurement of molecular processes using radiotracers labeled with positron-emitting isotopes (carbon-11/11C; fluorine-18/18F). The increased sensitivity of PET, coupled with the ability to produce biologically active tracers bearing PET imaging isotopes, could potentially enable the detection of tumor and small clusters of cells at infiltrative/invasive margins .
Portable direct-reading instruments by light-scattering method are increasingly used in airborne fine particulate matter (PM2.5) monitoring. However, there are limited calibration studies on such instruments by applying the gravimetric method as reference method in field tests.
An 8-month sampling was performed and 96 pairs of PM2.5 data by both the gravimetric method and the simultaneous light-scattering real-time monitoring (QT-50) were obtained from July, 2015 to February, 2016 in Shanghai. Temperature and relative humidity (RH) were recorded. Mann-Whitney U nonparametric test and Spearman correlation were used to investigate the differences between the two measurements. Multiple linear regression (MLR) model was applied to set up the calibration model for the light-scattering device.
Light-scattering measurements of PM2.5 by QT-50 instrument overestimated the concentration levels and were affected by temperature and RH. The calibration model for QT-50 instrument was firstly set up against the gravimetric method with temperature and RH adjusted.
Citation: Shi J, Chen F, Cai Y, Fan S, Cai J, Chen R, et al. (2017) Validation of a light-scattering PM2.5 sensor monitor based on the long-term gravimetric measurements in field tests. PLoS ONE 12(11): e0185700.
The objectives of this study were to set up the calibration model by investigating the relationship between the measurements by the light-scattering PM2.5 monitor (QT-50, Hivron, Beijing, China) and by the parallel gravimetric measurements, and further establish the method of field calibration for low-cost optical sensors. We are going to investigate the factors influencing the differences between the two sets of measurement data and eventually construct a validation model for the PM2.5 sensor instrument with temperature and RH adjusted, based on long-time field tests. Because the temperature and RH are largely different between indoor and outdoor environment, both indoor and outdoor samplings and comparisons were conducted at the same time to enable the validation model be applicable in a variety of environment.
SKC pumps (Aircheck Sampler, Model 224-PCXR8, SKC Inc., PA, USA) were used to collect the PM2.5 samples using a 2.5μm impactor (SKC Inc., PA, USA). A flow rate calibration chamber (SKC Gulf Coast Inc., Houston, TX, USA) was used before and after the sampling to facilitate the measurements of the flow rate (Liter per minute, LPM). For each sampling, a 37mm Quartz filter (Pall Corp., Ann Arbor, MI, USA) was pre-heated at 900C for 3h to remove carbon contamination. All Quartz filters were pre- and post-weighed in a temperature and RH constant room using a Mettler-Toledo AG285 electronic microbalance with 0.01mg sensitivity. Filters were repeatedly weighed until the differences between replicate weights were
To evaluate and validate QT50 for PM2.5 in field measurements, parallel sampling was performed by QT50, an established light-scattering instrument (MicroPEM) and by gravimetric method. QT50 and MicroPEM recorded PM2.5 data for every 10 min continuously and the filters were sampled for 2 days in the weekend or 4 days in weekdays. According to the beginning and ending time of the filter sampling, the real-time measurement data by QT-50 or MicroPEM were calculated into the 2-day or 4-day average values to be matched and comparable with the integrated average value by the gravimetric method. Eventually, 54 pairs of matched values were obtained and presented in Fig 2. The date points refer to each paired average values. Y-axis refers to PM2.5 average levels and X-axis refers to sampling date.
To test how the original PM2.5 data measured by QT-50 were improved after applying the calibration model, further comparison analyses were performed. Firstly, the median and the range of calibrated QT-50 data became closer to the level of the gravimetric data (Fig 5). By calculation, the ratio of calibrated QT-50 and gravimetric measurements decreased from 1.51(0.66) to 1.09(0.38). Secondly, the potential measurement bias by RH and temperature were significantly corrected. In the scattering plot of QT-50 after calibration, the PM2.5 concentration was not increased with the increase of RH anymore (Fig 3B), and the PM2.5 level was much closer to gravimetric measurement across different temperature (Fig 4B). Thirdly, by plotting the QT-50 data against the gravimetric data, the QT-50 calibration line was much closer to the theoretically ideal line of Y = X compared to the original QT-50 data line (Fig 6). The correlation between QT-50 and gravimetric measurement was improved by the increased adjusted R2 from 0.75 to 0.81 (Y = 0.81X+8.94). The MicroPEM data, which were considered as the reference light-scattering data, showed the adjusted R2 of 0.81 (Y = 1.29X-10.27).
Y axis refers to PM2.5 concentration based on the light-scattering method, and X axis refers to PM2.5 concentration measured by gravimetric instrument. The red line Y = X is achieved when light-scattering measurements (QT50, MicroPEM) were in an ideally perfect agreement with the gravimetric measurement.
Light-scattering instruments such as QT-50 could overestimate the PM2.5 levels. The calibration model was set up after a long-term sampling covering a wide range of PM2.5 concentration, temperature and RH.
Patients with Her-2+ metastatic breast cancer either with at least one 1-cm diameter brain metastasis or without brain metastases underwent dynamic carbon-11 radiolabelled lapatinib ([11C]lapatinib)-PET. Less than 20 μg of [11C]lapatinib was administered before and after 8 days of oral lapatinib (1,500 mg once daily). Radial arterial blood sampling was performed throughout the 90-min scan. The contribution of blood volume activity to the tissue signal was excluded to calculate lapatinib uptake in normal brain and metastases. Partitioning of radioactivity between plasma and tissue (V T) was calculated and the tissue concentration of lapatinib derived. Plasma lapatinib levels were measured and adverse events noted.
In order to evaluate lapatinib access into normal brain and brain metastases, a positron emission tomography (PET) study was performed with carbon-11 radiolabelled lapatinib ([11C]lapatinib) in patients with Her-2-positive breast cancer. Further, in order to test our hypothesis that therapeutic doses of lapatinib increase brain access into the brain and brain metastases, by blockage of the drug efflux pump, paired [11C]lapatinib-PET imaging in patients before and after therapeutic doses of lapatinib was performed. A schematic representation of our study hypothesis is shown in Figure 1.
Study hypothesis. It was hypothesised that brain penetration in normal brain would increase with therapeutic serum concentrations of lapatinib due to the effect of lapatinib on drug efflux pumps. Higher brain penetration in metastases compared with normal brain was also hypothesised due to the disruption of the BBB in cranial metastases. 11C, carbon-11 radiolabelled; BBB, blood-brain barrier; PET, positron emission tomography.
[11C]Lapatinib was prepared in a two-pot four-step synthesis, with intermediate preparation of [11C]-3-fluorobenzyl iodide (Figure 2). Cyclotron-derived [11C]CO2 was first reacted with 3-fluorophenylmagnesium bromide in tetrahydrofuran. The resulting acid was reduced with lithium aluminium hydride, followed by iodination reaction in the presence of hydriodic acid. The obtained [11C]-3-fluorobenzyl iodide was intermediately purified by solid-phase extraction, before being reacted with the lapatinib precursor in dimethylformamide in the presence of caesium carbonate. Purification of [11C]lapatinib was achieved by reverse-phase high-performance liquid chromatography (HPLC). The fraction containing the product was formulated into 20% ethanolic saline by solid-phase extraction, followed by filtration through a 0.2-μm Pall Tuffryn membrane (Pall Corporation, Port Washington, NY, USA). Quality control methods for clinical batches of [11C]lapatinib were developed in accordance with the European Pharmacopoeia guidelines.
Fully automated and good manufacturing process-compatible synthesis developed to label lapatinib with radiolabelled carbon-11 in the benzylic position. [11C]Lapatinib was prepared in a two-pot four-step synthesis, with intermediate preparation of [11C]-3-fluorobenzyl iodide that was reacted in the last step with the lapatinib precursor. 11C, carbon-11.