Frost Growth Investigation and Temperature Glide Refrigerants in a Fin-and-Tube Heat Exchanger

Bio methane is produced by removing undesirable components such as water vapor, carbon dioxide and other pollutants in a biogas upgrading process. Frosting the water vapor contained in the biogas is one of the dehydration processes used in a biogas upgrading process. In order to simulate a frost layer on a cold plate, many models have been developed. These models are valid for a limited temperature range. In this study, heat and mass transfer equations were used in a numerical approach to model the frost growth and its densification on the external side of a fin-and-tube heat exchanger. The model used in this study is valid for low temperatures from 0 to -65 °C and lower. The evaporation process of temperature glide refrigerants is also modelled. Results show that a decreased heat transfer rate occurred during frost mass growth on fins and rows. During its growth, frost layer thermal conductivity is relatively low leading to a decrease of the cooling load of the heat exchanger. On the other hand, frost layer thickness increases the external surface blockage, leading to higher pressure drop on the external side. This model has been validated by comparing numerical and experimental results

Mobile Agent Trajectory Prediction using Bayesian Nonparametric Reachability Trees

This paper presents an efficient trajectory prediction algorithm that has been developed to improve the performance of future collision avoidance and detection systems. The main idea is to embed the inferred intention information of surrounding agents into their estimated reachability sets to obtain a probabilistic description of their future paths. More specifically, the proposed approach combines the recently developed RRT-Reach algorithm and mixtures of Gaussian Processes. RRT-Reach was introduced by the authors as an extension of the closed-loop rapidly-exploring random tree (CL-RRT) algorithm to compute reachable sets of moving objects in real-time. A mixture of Gaussian processes (GP) is a flexible nonparametric Bayesian model used to represent a distribution over trajectories and have been previously demonstrated by the authors in a UAV interception and tracking of ground vehicles planning scheme. The mixture is trained using typical maneuvers learned from statistical data, and RRT-Reach utilizes samples from the GP to grow probabilistically weighted feasible paths of the surrounding vehicles. The resulting approach, denoted as RR-GP, has RRTReach's benefits of computing trajectories that are dynamically feasible by construction, therefore efficiently approximating the reachability set of surrounding vehicles following typical patterns. RRT-GP also features the GP mixture's benefits of providing a probabilistic weighting on the feasible trajectories produced by RRTReach, allowing our system to systematically weight trajectories by their likelihood. A demonstrative example on a car-like vehicle illustrates the advantages of the RR-GP approach by comparing it to two other GP-based algorithms. © 2011 by Professor Jonathan P. How, Massachusetts Institute of Technology. Published by the American Institute of Aeronautics and Astronautics, Inc

Periodontal Microorganisms, Obesity, Chronic Inflammation, and Type 1 Diabetes

Periodontal disease is a low-grade chronic inflammation in the tissues surrounding the teeth caused by multiple, mostly gram-negative pathogens. It is associated with diabetes, obesity, and chronic inflammation. The specific roles that periodontal microorganism play in these conditions are not well-studied. Hereby, we explored how periodontal bacteria from sub gingival plaque clustered in youth with and without type 1 diabetes, and how such patterns related to body-mass-index percentile (BMI percentile), C-reactive protein (CRP) and adiponectin. Cross-sectional data were collected from 105 youth with type 1 diabetes and 71 without diabetes. Participants were between 12 and 19 years of age receiving care at the Barbara Davis Center in Colorado, 2009-2011. Counts of 41 oral-bacteria from sub gingival-plaque were obtained using DNA-DNA hybridization, and grouped using cluster-analysis. Standardized-mean counts of each organism were computed and summed to get microbial-scores per cluster. A subset (n=101, 54 with type 1 diabetes) underwent dental examinations at the University of Colorado, School of Dental Medicine clinic. Participants were 15-years old on average; 51% were female; 73% non-Hispanic white; 37% overweight; the average diabetes duration was 8 years. About 48% brushed their teeth twice/day; 12% flossed once/day; 47% visited a dentist in the past 6 months. Bacterial clusters were identified and named after Socransky’s color-coded complexes as ‘blue-other’, ‘orange-blue’, ‘orange-red’, and ‘yellow-other’. Individuals with and without type 1 diabetes had similar microbial composition. Cases of type 1 diabetes ranking in the highest tertile of CRP were older, female, had higher Hemoglobin-A1c (HbA1c) and glucose levels, brushed their teeth at least twice a day but did not floss at all. Those in the highest tertile of adiponectin were similar. Gingival condition was similar across the tertiles of CRP and adiponectin. Cluster scores were not significantly different; however, overweight participants had qualitatively lower scores for clusters 2 and 3 than normal participants. Clusters of periodontal microorganisms were associated with CRP and adiponectin after accounting for potential confounders. The oral composition of microorganisms was similar among youth with and without type 1 diabetes. Normal and overweight youth with type 1 diabetes had similar profiles too. This may be due to young age of participants, relatively short type 1 diabetes duration, regular medical care, and low level of periodontal disease. CRP was positively-related to the ‘orange-blue’ cluster and adiponectin was negatively-related to the ‘Blue-Other ’ cluster

Comparison of Efficacy and Ocular Surface Disease Index Score between Bimatoprost, Latanoprost, Travoprost, and Tafluprost in Glaucoma Patients

Aim. The purpose of this study is to evaluate and compare the efficacy of 4 prostaglandin analogues (PGAs) and to determine the incidence of ocular surface disease in newly diagnosed, primary open-angle glaucoma (POAG) patients started on one of those 4 PGAs: bimatoprost (benzalkonium chloride, BAK, 0.3 mg/mL), latanoprost (BAK 0.2 mg/mL), travoprost (polyquad), and tafluprost (BAK-free). Patients and Methods. In this single-center, open-label trial, 32 patients newly diagnosed with POAG were randomly started on one of the four PGAs. All patients underwent a complete ophthalmological exam at presentation and at 1, 3, and 6 months of follow-up. Dry eye disease (DED) was assessed using the original Ocular Surface Disease Index (OSDI) questionnaire, in order to evaluate the impact of the drops on the quality of life of patients. Results. The mean age was 60.06 years ± 11.76. All four drugs equally and significantly reduced the intraocular pressure (IOP) with respect to the baseline IOP. There was a trend for a slightly greater reduction of IOP with bimatoprost, but the difference was not found to be statistically significant when compared to other PGAs. OSDI scores were significantly superior for travoprost (10.68 ± 5.73) compared to the other three drugs (p<0.05). Latanoprost caused the most significant eyelash growth and iris discoloration. Conjunctival hyperemia and superficial keratitis occurrence were similar in the four groups. Conclusion. All prostaglandin analogues equally and significantly reduce the IOP in patients with POAG. According to the results of the OSDI score, latanoprost seems to be the least tolerated among the four drugs

Mott Transition and Volume Law Entanglement with Neural Quantum States

The interplay between delocalisation and repulsive interactions can cause electronic systems to undergo a Mott transition between a metal and an insulator. Here we use neural network hidden fermion determinantal states (HFDS) to uncover this transition in the disordered, fully-connected Hubbard model. Whilst dynamical mean-field theory (DMFT) provides exact solutions to physical observables of the model in the thermodynamic limit, our method allows us to directly access the wavefunction for finite system sizes well beyond the reach of exact diagonalisation. We directly benchmark our results against state-of-the-art calculations obtained using a Matrix Product State (MPS) ansatz. We demonstrate how HFDS is able to obtain more accurate results in the metallic regime and in the vicinity of the transition, with the volume law of entanglement exhibited by the system being prohibitive to the MPS ansatz. We use the HFDS method to calculate the amplitudes of the wavefunction, the energy and double occupancy, the quasi-particle weight and the energy gap, hence providing novel insights into this model and the nature of the transition. Our work paves the way for the study of strongly correlated electron systems with neural quantum states.Comment: Main Text: 5 pages, 3 figure

Non-Invasive Photoacoustic Imaging of In Vivo Mice with Erythrocyte Derived Optical Nanoparticles to Detect CAD/MI.

Coronary artery disease (CAD) causes mortality and morbidity worldwide. We used near-infrared erythrocyte-derived transducers (NETs), a contrast agent, in combination with a photoacoustic imaging system to identify the locations of atherosclerotic lesions and occlusion due to myocardial-infarction (MI). NETs (≈90 nm diameter) were fabricated from hemoglobin-depleted mice erythrocyte-ghosts and doped with Indocyanine Green (ICG). Ten weeks old male C57BL/6 mice (n = 9) underwent left anterior descending (LAD) coronary artery ligation to mimic vulnerable atherosclerotic plaques and their rupture leading to MI. 150 µL of NETs (20 µM ICG,) was IV injected via tail vein 1-hour prior to photoacoustic (PA) and fluorescence in vivo imaging by exciting NETs at 800 nm and 650 nm, respectively. These results were verified with histochemical analysis. We observed ≈256-fold higher PA signal from the accumulated NETs in the coronary artery above the ligation. Fluorescence signals were detected in LAD coronary, thymus, and liver. Similar signals were observed when the chest was cut open. Atherosclerotic lesions exhibited inflammatory cells. Liver demonstrated normal portal tract, with no parenchymal necrosis, inflammation, fibrosis, or other pathologic changes, suggesting biocompatibility of NETs. Non-invasively detecting atherosclerotic plaques and stenosis using NETs may lay a groundwork for future clinical detection and improving CAD risk assessment

Functional and Structural Characterization of Chimeras of a Bacterial Genotoxin and Human Type I DNAse

Chimeras composed of the cdtB gene of a novel bacterial genotoxin and the human type I DNAse I gene were constructed and their products characterized relative to the biochemical and enzymatic properties of the native proteins. The product of a cdtB/DNAse I chimera formed a heterotrimer with the CdtA and CdtC subunits of the genotoxin, and targeted mutations increased the specific activity of the hybrid protein. Expression of active chimeric gene products established that the CdtB protein is an atypical divalent cation-dependent endonuclease and demonstrated the potential for genetically engineering a new class of therapeutic agent for inhibiting the proliferation of cancer cells