Molecular Tracers Research Articles

Assessment of Aliphatic Hydrocarbons in Sediments of Shatt Al-Arab River, Southern Iraq, North East Arabian Gulf

Shatt Al-Arab River is one of the important rivers for water supply, industry and irrigation in Basrah City, south of Iraq. It's also supply drinking water to users in the region. Despite the significance of this river, there is a lack of previous studies dealing with petroleum pollution especially for geochemical studies of organic matter in the river sediments using molecular tracer methods. Therefore, the identification and quantification of petroleum hydrocarbons in this river at the elemental and molecular levels will be of the utmost interest. Sediments were analyzed in nine Shatt Al-Arab River stations. Texture was silty clay or silty sand. TOC and TN ranged from 0.39-0.90 and 0.02-0.16%. OM varied from 17.43-34.36 µg g-1 dw, representing 0.27-0.87% of TOC. AHs ranged from 3.19-10.27 µg g-1 dw and constituted 16.07-29.88% of OM. Total n-alkanes concentrations ranged from 0.08-42.58 µg g-1 dw with carbon numbers from C11-C34 were identified. N-alkanes content was relatively moderate compared to sites contaminated with oil worldwide. Dominance of even carbon number n-alkanes (C11-C20) with CPI and LMW/HMW values close to unity, indicated to oil-related n-alkanes. This was verified by the values of U/R (1.27-2.45), pri/phy (0.82-1.00), C17/pri (0.70-1.94) and C18/phy (0.95-1.56) ratios and the presence of UCM. Biogenic contributions were detected within the n-alkanes distribution of C17-C31 and CPI and LMW/HMW values of <1 that mainly related to terrestrial plants, phytoplankton, algae and bacteria sources, confirmed by TAR (0.79-2.15) and C31/C19 ratio (0.28-1.62) values. However, the contribution from biogenic hydrocarbons is overshadowed by petroleum origin n-alkanes. This was obvious by the presence of UCM. PCA showed concordant results with n-alkanes ratios indicating mixed n-alkanes sources in sediments. Hopanes and steranes in sediments displayed similar signatures that were characteristic of mature organic matter contribution from oil contaminations.

What Sets the Massive Star Formation Rates and Efficiencies of Giant Molecular Clouds?

Abstract Galactic star formation scaling relations show increased scatter from kpc to sub-kpc scales. Investigating this scatter may hold important clues to how the star formation process evolves in time and space. Here, we combine different molecular gas tracers, different star formation indicators probing distinct populations of massive stars, and knowledge of the evolutionary state of each star-forming region to derive the star formation properties of ∼150 star-forming complexes over the face of the Large Magellanic Cloud (LMC). We find that the rate of massive star formation ramps up when stellar clusters emerge and boost the formation of subsequent generations of massive stars. In addition, we reveal that the star formation efficiency of individual giant molecular clouds (GMCs) declines with increasing cloud gas mass ( ). This trend persists in Galactic star-forming regions and implies higher molecular gas depletion times for larger GMCs. We compare the star formation efficiency per freefall time ( ) with predictions from various widely used analytical star formation models. While these models can produce large dispersions in similar to those in observations, the origin of the model-predicted scatter is inconsistent with observations. Moreover, all models fail to reproduce the observed decline of with increasing in the LMC and the Milky Way. We conclude that analytical star formation models idealizing global turbulence levels and cloud densities and assuming a stationary star formation rate (SFR) are inconsistent with observations from modern data sets tracing massive star formation on individual cloud scales. Instead, we reiterate the importance of local stellar feedback in shaping the properties of GMCs and setting their massive SFR.

Brown adipose tissue and lipid metabolism imaging.

Brown adipose tissue (BAT) research has evolved from an underestimated to a fast developing field. Its assumed curing properties for the world wide epidemic obesity, and its related diseases, makes this tissue an interesting target for a broad amount of non-invasive molecular BAT tracers. Apart from 18F-FDG PET/CT there are several methods to detect BAT and measure its metabolism in a more appropriate way. Especially interesting is the measure of lipid turnover, because fatty acids comprise the main fuel for active BAT. This review outlines different imaging modalities suitable for BAT imaging with the overall goal to explain the yet not completely understood mechanism in BAT and its quantitative contribution to whole body lipid and energy metabolism. Publications with focus on brown adipose tissue and lipid metabolism imaging are analyzed, different imaging approaches are introduced and promising BAT tracers are presented. Radiolabelled and fluorescent fatty acids, labelled particles, 3H-Triolein and ADIFAB staining can give information about the inflow and therefore about the utilization of fatty acids which represents the activation state in vivo/in vitro. Non-invasive scanning with CT or MRI is a useful addition to those techniques. Lipid metabolism imaging offers the opportunity to visualize and quantify yet undiscovered aspects of BAT metabolic activities and is key to completely clarify its role in whole body lipid and energy metabolism.

Nuclear spirals in the inner Milky Way

We use hydrodynamical simulations to construct a new coherent picture for the gas flow in the Central Molecular Zone (CMZ), the region of our Galaxy within $R\leq 500\, \mathrm{pc}$. We relate connected structures observed in $(l,b,v)$ data cubes of molecular tracers to nuclear spiral arms. These arise naturally in hydrodynamical simulations of barred galaxies, and are similar to those that can be seen in external galaxies such as NGC4303 or NGC1097. We discuss a face-on view of the CMZ including the position of several prominent molecular clouds, such as Sgr B2, the $20\,{\rm km\, s^{-1}}$ and $50\,{\rm km\, s^{-1}}$ clouds, the polar arc, Bania Clump 2 and Sgr C. Our model is also consistent with the larger scale gas flow, up to $R\simeq 3\,\rm kpc$, thus providing a consistent picture of the entire Galactic bar region.

Tortuosity of mesoporous alumina catalyst supports: Influence of the pore network organization

Inverse liquid chromatography experiments were performed on five mesoporous alumina catalyst supports with similar porosity and different pore size distributions. By varying the size of the molecular tracer, it was shown that the diffusion regime in our conditions is molecular diffusion. Hindered diffusion was not observed even for squalane, a C30 molecule. Using the slope of the Van Deemter equation, the tortuosity of each alumina support was determined. The results are in disagreement with literature correlations: although all alumina supports had similar total porosities, the measured tortuosity values are really different and much higher than those predicted by these theoretical models. This discrepancy has been resolved by assuming a two–level pore network organization, whose characteristics can be entirely estimated from a classical nitrogen adsorption isotherm. This simple methodology allows to evaluate the mass transfer in mesoporous alumina supports knowing their textural properties, which is an important issue for the design and optimization of numerous catalytic processes.

Enhanced interstitial fluid drainage in the hippocampus of spontaneously hypertensive rats

Hypertension is associated with cognitive decline and various forms of dementia, including Alzheimer’s disease. In animal models of hypertension, many of Alzheimer’s disease characteristics are recapitulated, including brain atrophy, cognitive decline, amyloid β accumulation and blood brain barrier dysfunction. Removal of amyloid β and other waste products depends in part on clearance via the brain interstitial fluid (ISF). Here we studied the impact of hypertension on ISF drainage, using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). At 8 months, high (500 kD) and low (3 kD) fluorescent molecular weight tracers released passively into the hippocampus showed a drastically enhanced spreading in SHR. Tracer spreading was inhomogeneous, with accumulation at ISF-CSF borders, around arteries, and towards the stratum lacunosum moleculare. These locations stained positively for the astrocyte marker GFAP, and aquaporin 4. Despite enhanced dispersion, clearance of tracers was not affected in SHR. In conclusion, these data indicate enhanced bulk flow of ISF in the hippocampus of hypertensive rats. ISF drains along astrocytes towards the cerebrospinal fluid compartment, which leads to sieving of high molecular weight solutes. Sieving may lead to a local increase in the concentration of waste products and potentially promotes the aggregation of amyloid β.

The geochemistry of naturally occurring methane and saline groundwater in an area of unconventional shale gas development

Since naturally occurring methane and saline groundwater are nearly ubiquitous in many sedimentary basins, delineating the effects of anthropogenic contamination sources is a major challenge for evaluating the impact of unconventional shale gas development on water quality. This study investigates the geochemical variations of groundwater and surface water before, during, and after hydraulic fracturing and in relation to various geospatial parameters in an area of shale gas development in northwestern West Virginia, United States. To our knowledge, we are the first to report a broadly integrated study of various geochemical techniques designed to distinguish natural from anthropogenic sources of natural gas and salt contaminants both before and after drilling. These measurements include inorganic geochemistry (major cations and anions), stable isotopes of select inorganic constituents including strontium (87Sr/86Sr), boron (δ11B), lithium (δ7Li), and carbon (δ13C-DIC), select hydrocarbon molecular (methane, ethane, propane, butane, and pentane) and isotopic tracers (δ13C-CH4, δ13C-C2H6), tritium (3H), and noble gas elemental and isotopic composition (helium, neon, argon) in 105 drinking-water wells, with repeat testing in 33 of the wells (total samples=145). In a subset of wells (n=20), we investigated the variations in water quality before and after the installation of nearby (<1km) shale-gas wells. Methane occurred above 1 ccSTP/L in 37% of the groundwater samples and in 79% of the samples with elevated salinity (chloride>50mg/L). The integrated geochemical data indicate that the saline groundwater originated via naturally occurring processes, presumably from the migration of deeper methane-rich brines that have interacted extensively with coal lithologies. These observations were consistent with the lack of changes in water quality observed in drinking-water wells following the installation of nearby shale-gas wells. In contrast to groundwater samples that showed no evidence of anthropogenic contamination, the chemistry and isotope ratios of surface waters (n=8) near known spills or leaks occurring at disposal sites mimicked the composition of Marcellus flowback fluids, and show direct evidence for impact on surface water by fluids accidentally released from nearby shale-gas well pads and oil and gas wastewater disposal sites. Overall this study presents a comprehensive geochemical framework that can be used as a template for assessing the sources of elevated hydrocarbons and salts to water resources in areas potentially impacted by oil and gas development.

HC3N observations of nearby galaxies

Aims. We aim to systematically study the properties of the different transitions of the dense molecular gas tracer HC3N in galaxies. Methods. We have conducted single-dish observations of HC3N emission lines towards a sample of nearby gas-rich galaxies. HC3N(J=2-1) was observed in 20 galaxies with Effelsberg 100-m telescope. HC3N(J=24-23) was observed in nine galaxies with the 10-m Submillimeter Telescope (SMT). Results. HC3 N 2-1 is detected in three galaxies: IC 342, M 66 and NGC 660 (> 3 {\sigma}). HC3 N 24-23 is detected in three galaxies: IC 342, NGC 1068 and IC 694. This is the first measurements of HC3N 2-1 in a relatively large sample of external galaxies, although the detection rate is low. For the HC3 N 2-1 non-detections, upper limits (2 {\sigma}) are derived for each galaxy, and stacking the non-detections is attempted to recover the weak signal of HC3N. But the stacked spectrum does not show any significant signs of HC3N 2-1 emission. The results are also compared with other transitions of HC3N observed in galaxies. Conclusions. The low detection rate of both transitions suggests low abundance of HC3N in galaxies, which is consistent with other observational studies. The comparison between HC3N and HCN or HCO+shows a large diversity in the ratios between HC3N and HCN or HCO+. More observations are needed to interpret the behavior of HC3N in different types of galaxies.

Cerebrospinal and interstitial fluid transport via the glymphatic pathway modeled by optimal mass transport

The glymphatic pathway is a system which facilitates continuous cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange and plays a key role in removing waste products from the rodent brain. Dysfunction of the glymphatic pathway may be implicated in the pathophysiology of Alzheimer's disease. Intriguingly, the glymphatic system is most active during deep wave sleep general anesthesia. By using paramagnetic tracers administered into CSF of rodents, we previously showed the utility of MRI in characterizing a macroscopic whole brain view of glymphatic transport but we have yet to define and visualize the specific flow patterns. Here we have applied an alternative mathematical analysis approach to a dynamic time series of MRI images acquired every 4min over ∼3h in anesthetized rats, following administration of a small molecular weight paramagnetic tracer into the CSF reservoir of the cisterna magna. We use Optimal Mass Transport (OMT) to model the glymphatic flow vector field, and then analyze the flow to find the network of CSF-ISF flow channels. We use 3D visualization computational tools to visualize the OMT defined network of CSF-ISF flow channels in relation to anatomical and vascular key landmarks from the live rodent brain. The resulting OMT model of the glymphatic transport network agrees largely with the current understanding of the glymphatic transport patterns defined by dynamic contrast-enhanced MRI revealing key CSF transport pathways along the ventral surface of the brain with a trajectory towards the pineal gland, cerebellum, hypothalamus and olfactory bulb. In addition, the OMT analysis also revealed some interesting previously unnoticed behaviors regarding CSF transport involving parenchymal streamlines moving from ventral reservoirs towards the surface of the brain, olfactory bulb and large central veins.

Kinematics and properties of the central molecular zone as probed with [C ii

The Galactic Central Molecular Zone (CMZ) is a region containing massive and dense molecular clouds, with dynamics driven by a variety of energy sources including a massive black hole. It is thus the nearest template for understanding physical processes in extragalactic nuclei. The CMZ's neutral interstellar gas has been mapped spectrally in many neutral atomic and molecular gas tracers, but the ionized and CO-dark H2 regions are less well traced spectroscopically. We mapped the fine structure line of C+ at 158 microns, [C II], to identify and characterize features of the ionized gas in the CMZ, including UV irradiated neutral gas, photon dominated regions (PDRs), CO-dark H2 gas, and highly ionized gas. We observed the [C II] 158-micron fine structure line with high spectral resolution using Herschel HIFI with two perpendicular On-the-Fly strip scans, along l = -0.8 to +0.8 and b = -0.8 to +0.8, both centered on (l,b) = (0,0). We analyzed the spatial-velocity distribution of the [C II] data and compared them to those of [C I] and CO, and to dust continuum maps, in order to determine the properties and distribution of the UV irradiated gas and its dynamics within the CMZ. The longitude- and latitude-velocity maps of [C II] trace portions of the orbiting open gas streams of dense molecular clouds, the cloud G0.253+0.016, also known as the Brick, the Arched Filaments, and the ionized gas near Sgr A and Sgr B2. We use the [C II] and auxiliary data to determine the physical and dynamical properties of these CMZ features. The [C II] emission arises primarily from dense PDRs and highly ionized gas, and is an important tracer of the kinematics and physical conditions of this gas.

Important fossil source contribution to brown carbon in Beijing during winter

Organic aerosol (OA) constitutes a substantial fraction of fine particles and affects both human health and climate. It is becoming clear that OA absorbs light substantially (hence termed Brown Carbon, BrC), adding uncertainties to global aerosol radiative forcing estimations. The few current radiative-transfer and chemical-transport models that include BrC primarily consider sources from biogenic and biomass combustion. However, radiocarbon fingerprinting here clearly indicates that light-absorbing organic carbon in winter Beijing, the capital of China, is mainly due to fossil sources, which contribute the largest part to organic carbon (OC, 67 ± 3%) and its sub-constituents (water-soluble OC, WSOC: 54 ± 4%, and water-insoluble OC, WIOC: 73 ± 3%). The dual-isotope (Δ14C/δ13C) signatures, organic molecular tracers and Beijing-tailored emission inventory identify that this fossil source is primarily from coal combustion activities in winter, especially from the residential sector. Source testing on Chinese residential coal combustion provides direct evidence that intensive coal combustion could contribute to increased light-absorptivity of ambient BrC in Beijing winter. Coal combustion is an important source to BrC in regions such as northern China, especially during the winter season. Future modeling of OA radiative forcing should consider the importance of both biomass and fossil sources.

Erratum to: Statistical Measurement of Counterflow Turbulence in Superfluid Helium-4 Using $$\hbox {He}^{{*}}_{2}$$ He 2 ∗ Tracer-Line Tracking Technique

We report preliminary results of a systematic study of the flow of normal fluid component in steady-state quantum turbulence in thermal counterflow of superfluid \(^{4}\hbox {He}\) using a high-precision flow visualisation technique based on the tracking of thin lines of \(\hbox {He}_2^{*}\) molecular tracers. Non-trivial profiles of mean velocity and turbulent fluctuation across the channel are observed with complicated temperature- and heat flux-dependencies. Mean turbulence intensity, however, depends on velocity only very weakly and is controlled primarily by the temperature.

Abstract P4-01-01: Phase II in-human dose escalation study of the optical molecular imaging tracer bevacizumab-800cw for molecular fluorescence guided surgery in primary breast cancer patients

Abstract Introduction Molecular Fluorescence Guided Surgery (MFGS) might be used for intraoperative detection of positive resection margins in breast conserving surgery (BCS) for the treatment of breast cancer. Currently, the presence of tumor positive resection margins can only be assessed ex vivo by histopathological analysis of the excised tissue, which takes up to 5 working days. The current study defined the optimal dose of the near-infrared (NIR) optical imaging tracer bevacizumab-800CW to enable intraoperative detection and image-guided pathology of tumor positive resection margins in breast cancer patients. Methods Molecular Fluorescence Guided Surgery during BCS was performed in subjects treated for primary breast cancer. The NIR optical imaging tracer bevacizumab-800CW targeting vascular endothelial growth factor A was administered intravenously three days prior to surgery in four escalating dose groups (4.5mg, 10mg, 25mg and 50mg). NIR fluorescent signals were detected real-time using an intraoperative fluorescence camera system (SurgVision BV). Standardized ex vivo analyses of tumor-to-normal ratios (TNR) were performed to define the optimal tracer dose using a BlackBox imaging system (SurgVision BV) for imaging fresh bread loaf slices, a NIR fluorescence flatbed scanner (Odyssey, Li-Cor) for imaging 10µm slices of formalin-fixed paraffin-embedded (FFPE) blocks, NIR Confocal Laser Endomicroscopy (CLE, Mauna Kea Technologies) and multi-diameter single fiber reflectance and single fiber fluorescence (MDSFR/SFF) spectroscopy quantification to enable correction for the influence of tissue optical properties on fluorescence in tumor and normal breast tissue. Results Currently, 12 subjects have been included and analyzed in four dosing groups. All tumors showed specific tracer uptake at macroscopic and microscopic level during ex vivo analyses, confirmed by histopathology. Quantification of NIR fluorescent signals showed higher TNRs by increasing doses up to 25mg. No further increase in TNR was seen in the 50mg dose group. CLE showed the feasibility of visualization of the tracer accumulation in tumor tissue compared to normal tissue at a microscopic level. MDSFR/SFF spectroscopy objectively confirmed the dose dependency up to 25mg. Conclusion and future perspective Intravenous administration of bevacizumab-800CW in doses up to 50mg is safe and highly tumor specific, showing a plateau of TNR at 25mg and 50mg. Further expansion of the dosing cohorts of 10mg and 25mg with additional seven patients per group will be performed to establish the optimal dose for MFGS during BCS for an upcoming phase III multicenter randomized controlled trial. By enabling MFGS during BCS the surgical treatment of primary breast cancer patients might be optimized by a reduced need for re-excision surgery and thereby reducing the risk of co-morbidity, psychological burden, poor cosmesis and healthcare costs. Citation Format: van Dam GM, Koller M, Qiu SQ, Linssen MD, de Vries J, Jansen L, Kelder W, de Jong JS, Jorritsma-Smit A, van der Vegt B, Robinson DJ, Nagengast WB. Phase II in-human dose escalation study of the optical molecular imaging tracer bevacizumab-800cw for molecular fluorescence guided surgery in primary breast cancer patients [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-01-01.

Optimized Translocator Protein Ligand for Optical Molecular Imaging and Screening

Translocator protein (TSPO) is a validated target for molecular imaging of a variety of human diseases and disorders. Given its involvement in cholesterol metabolism, TSPO expression is commonly elevated in solid tumors, including glioma, colorectal cancer, and breast cancer. TSPO ligands capable of detection by optical imaging are useful molecular tracers for a variety of purposes that range from quantitative biology to drug discovery. Leveraging our prior optimization of the pyrazolopyrimidine TSPO ligand scaffold for cancer imaging, we report herein a new generation of TSPO tracers with superior binding affinity and suitability for optical imaging and screening. In total, seven candidate TSPO tracers were synthesized and vetted in this study; the most promising tracer identified (29, Kd = 0.19 nM) was the result of conjugating a high-affinity TSPO ligand to a fluorophore used routinely in biological sciences (FITC) via a functional carbon linker of optimal length. Computational modeling suggested that an n-alkyl linker of eight carbons in length allows for positioning of the bulky fluorophore distal to the ligand binding domain and toward the solvent interface, minimizing potential ligand-protein interference. Probe 29 was found to be highly suitable for in vitro imaging of live TSPO-expressing cells and could be deployed as a ligand screening and discovery tool. Competitive inhibition of probe 29 quantified by fluorescence and 3H-PK11195 quantified by traditional radiometric detection resulted in equivalent affinity data for two previously reported TSPO ligands. This study introduces the utility of TSPO ligand 29 for in vitro imaging and screening and provides a structural basis for the development of future TSPO imaging ligands bearing bulky signaling moieties.

Molecular Imaging of Vulnerable Coronary Plaque: A Pathophysiologic Perspective

Atherothrombotic events in coronary arteries are most often due to rupture of unstable plaque resulting in myocardial infarction. Radiolabeled molecular imaging tracers directed toward cellular targets that are unique to unstable plaque can serve as a powerful tool for identifying high-risk patients and for assessing the potential of new therapeutic approaches. Two commonly available radiopharmaceuticals-18F-FDG and 18F-NaF-have been used in clinical research for imaging coronary artery plaque, and ongoing clinical studies are testing whether there is an association between 18F-NaF uptake and future atherothrombotic events. Other, less available, tracers that target macrophages, endothelial cells, and apoptotic cells have also been tested in small groups of patients. Adoption of molecular imaging of coronary plaque into clinical practice will depend on overcoming major hurdles, ultimately including evidence that the detection of unstable plaque can change patient management and improve outcomes.

NMR Spin-Lock Induced Crossing (SLIC) dispersion and long-lived spin states of gaseous propane at low magnetic field (0.05 T)

When parahydrogen reacts with propylene in low magnetic fields (e.g., 0.05T), the reaction product propane develops an overpopulation of pseudo-singlet nuclear spin states. We studied how the Spin-Lock Induced Crossing (SLIC) technique can be used to convert these pseudo-singlet spin states of hyperpolarized gaseous propane into observable magnetization and to detect 1H NMR signal directly at 0.05T. The theoretical simulation and experimental study of the NMR signal dependence on B1 power (SLIC amplitude) exhibits a well-resolved dispersion, which is induced by the spin-spin couplings in the eight-proton spin system of propane. We also measured the exponential decay time constants (TLLSS or TS) of these pseudo-singlet long-lived spin states (LLSS) by varying the time between hyperpolarized propane production and SLIC detection. We have found that, on average, TS is approximately 3 times longer than the corresponding T1 value under the same conditions in the range of pressures studied (up to 7.6atm). Moreover, TS may exceed 13s at pressures above 7atm in the gas phase. These results are in agreement with the previous reports, and they corroborate a great potential of long-lived hyperpolarized propane as an inhalable gaseous contrast agent for lung imaging and as a molecular tracer to study porous media using low-field NMR and MRI.

Molecular tagging velocimetry by direct phosphorescence in gas microflows: Correction of Taylor dispersion

Molecular tagging velocimetry is a little-intrusive technique based on the properties of specific molecules able to emit luminescence once properly excited. Several variants of this technique have been successfully developed for analyzing external gas flows or internal gas flows in large systems. There is, however, very few experimental data on molecular tagging velocimetry for gas flows in mini or microsystems, and these data are strongly affected by the molecular diffusion of the tracer molecules. In the present paper, it is demonstrated that the velocity field in gas microflows cannot be directly deduced from the measured displacement field without taking into account Taylor dispersion effects. For that purpose, the benchmark case of a Poiseuille gas flow through a rectangular channel 960μm in depth is experimentally investigated by micro molecular tagging velocimetry using acetone vapor as a molecular tracer. An appropriate reconstruction method based on the advection diffusion equation is used to process the data and to correctly extract the velocity profiles. The comparison of measured velocities with flowrate data and with theoretical velocity profiles shows a good agreement, whereas when the reconstruction method is not implemented, the extracted velocity field exhibits qualitative and quantitative anomalies, such as a non-physical slip at the walls. The robustness of the reconstruction method is demonstrated on flows with light and heavy molecular species, namely helium and argon, at atmospheric as well as at lower pressure conditions, for which diffusion effects are stronger. The obtained results represent an encouraging step for future analysis of rarefied gas microflows.

Quantification of furandiones in ambient aerosol

Furandiones are products of the photooxidation of anthropogenic volatile organic compounds (VOC), like toluene, and contribute to secondary organic aerosol (SOA). Because few molecular tracers of anthropogenic SOA are used to assess this source in ambient aerosol, developing a quantification method for furandiones holds a great importance. In this study, we developed a direct and highly sensitive gas chromatography-mass spectrometry method for the quantitative analysis of furandiones in fine particulate matter that is mainly free from interference by structurally-related dicarboxylic acids. Our application of this method in Iowa City, IA provides the first ambient measurements of four furandiones: 2,5-furandione, 3-methyl-2,5-furandione, dihydro-2,5-furandione, and dihydro-3-methyl-2,5-furandione. Furandiones were detected in all collected samples with a daily average concentration of 9.1 ± 3.8 ng m−3. The developed method allows for the accurate measurement of the furandiones concentrations in ambient aerosol, which will support future evaluation of these compounds as tracers for anthropogenic SOA and assessment of their potential health impacts.

Use of Cyclic Backbone NGR-Based SPECT to Increase Efficacy of Postmyocardial Infarction Angiogenesis Imaging.

As CD13 is selectively expressed in angiogenesis, it can serve as a target for molecular imaging tracers to noninvasively visualize angiogenic processes in vivo. The CD13-targeting moiety NGR was synthesized and cyclized by native chemical ligation (NCL) instead of disulfide bridging, leading to a cyclic peptide backbone: cyclo(Cys-Asn-Gly-Arg-Gly) (coNGR). Beside this new monomeric coNGR, a tetrameric NGR peptide co(NGR)4 was designed and synthesized. After radiolabeling, their in vitro and in vivo characteristics were determined. Both coNGR-based imaging agents displayed considerably higher standardized uptake values (SUVs) at infarcted areas compared to the previously reported disulfide-cyclized cNGR imaging agent. Uptake patterns of 111In-coNGR and 111In-co(NGR)4 coincided with CD13 immunohistochemistry on excised hearts. Blood stability tests indicated better stability for both novel imaging agents after 50 min blood incubation compared to the disulfide-cyclized cNGR imaging agent. In mice, both coNGR peptides cleared rapidly from the blood mainly via the kidneys. In addition, co(NGR)4 showed a significantly higher specific uptake in infarcted myocardium compared to coNGR and thus is a promising sensitive imaging agent for detection of angiogenesis in infarcted myocardium.

Clinical Study on Computerized Molecular Imaging Tracing Stem Cell Transplantation for Patients with Myocardial Infarction

To explore the clinical application value of computer molecular imaging tracing stem cell transplantation in the treatment of myocardial infarction. Method: 90 patients with myocardial infarction admitted in our hospital from 2014.06 to 2016.06 were selected as subjects of this study, were randomly divided into two groups of 45 cases, the control group was treated with conventional therapy. The observation group was given molecular imaging tracing stem cell transplantation on the basis of conventional therapy. The patients in the two groups were treated for 3 weeks consecutively. After treatment, the patients in the two groups were followed up for 6 months. The total effective rate, left ventricular function index and complication rate after treatment were observed and compared. Results: The total effective rate of the treatment group was 97.8%, which was significantly higher than that of the control group (75.6%). The difference was statistically significant (P <0.05). After different treatment, the levels of CO and LVEF in the observation group were significantly higher than those in the control group, and the LVESV was significantly lower than that in the control group (P <0.05). There was no significant difference in LVEDD between the two groups (P> 0.05). The incidence of complications in the observation group was 4.4%, which was significantly lower than that in the control group (P <0.05). Conclusions: Molecular imaging tracer stem cell transplantation for the treatment of patients with MI, the effect is significant, can significantly improve ventricular systolic and diastolic function in patients, inhibit ventricular remodeling, and the incidence of complications during treatment is low, safe and reliable, help to improve the lives of MI patients Quality, improve the prognosis.