The "wet pressure drop" of oil mist filters (i.e. the increase in differential pressure of the air flow due to loading of the filter with liquid) is presented as a function of two mechanisms by which ...coalesced oil is transported through the filter. These mechanisms operate in separate regions of the filter and make separate (and separately measurable) contributions to the overall wet pressure drop. This new concept, which was first formulated qualitatively in a phenomenological model by Kampa et al. (2014), leads to semi-quantitative predictions regarding the dependence of pressure drop Delta p and saturation S on filter operating conditions, filter properties and liquid properties. These predictions are first formulated and then validated for a range of wettable and non-wettable filter media in combination with 4 mineral oils of different viscosity. The key findings, summarized below, are consistent with the model and apply to both wettable and non-wettable media. Oil transport across media interfaces (i.e. transitions between regions of different porosity and/or wettability) was associated with a relatively sharp increase in pressure drop Delta p and oil saturation S over a very thin layer of the filter (a " Delta p jump"). The magnitude of this Delta p jump was determined by the media properties. It correlated well with the respective static break-through pressures for oil or air, but did not depend on the oil viscosity and loading rate of the filter (at constant air velocity). Oil transport through channel regions of the filter (i.e. the regions connecting interfaces) was associated with a linear increase in Delta p with channel length and liquid throughput. The corresponding saturation level S was relatively flat throughout the channel region and lower than at an interface. (Both quantities are media dependent, of course.) An increase in oil viscosity mu (at constant oil throughput) led to different responses depending on filter wettability.
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•Two distinct transport mechanisms for coalesced liquid govern the “wet” pressure drop.•Transport across capillary interfaces causes Δp jumps associated with film formation.•Internal ...transport occurs via multiple parallel channels with constant Δp/length.
A phenomenological model is presented to explain the increase in pressure drop (Δp) of air filters during steady operation with oil mist. It is based on (currently) semi-quantitative conclusions obtained from measurements of liquid distribution patterns in the media associated with the transport of coalesced liquid by the flowing air. Correlation of these patterns in space and time with the evolution of the pressure drop suggests that the over-all increase in Δp (the “wet” pressure drop) is governed by two distinctly different liquid transport mechanisms:
A steep Δp jump is required to overcome the capillary exit (or entry) pressure and pump liquid into non-wettable, or out of wettable fibrous matrices. It is associated with the formation of a thin liquid film covering almost the entire front (or rear) face of the respective media. With the help of a polymerization technique to “freeze” the liquid distribution, the film is shown to be confined to the outermost surface without entering the media while the aerosol flow is on.
Liquid transport inside the media is shown to occur in multiple parallel channels spanning almost the entire thickness of a filter. The channel Δp associated with this transport mechanism increases linearly with media thickness. Wettable media form numerous fine channels which feed a liquid film on the rear face by which drainage takes place. Non-wettable media form fewer, relatively wide channels ending in large drops on the rear face, through which drainage takes place during steady operation.
Sandwiched combinations of wettable and non-wettable media show the same combination of features in their respective Δp curves. There are separate Δp jumps and channel regions for each media type. In case of a transition from wettable to non-wettable media, the combined exit and entry Δp jump takes place at the internal interface.
The ENCODE (ENCyclopedia of DNA Elements) Project Feingold, E A; Good, P J; Guyer, M S ...
Science (American Association for the Advancement of Science),
10/2004, Letnik:
306, Številka:
5696
Journal Article
Recenzirano
The ENCyclopedia of DNA Elements (ENCODE) Project aims to identify all functional elements in the human genome sequence. The pilot phase of the Project is focused on a specified 30 megabases (~1%) of ...the human genome sequence and is organized as an international consortium of computational and laboratory-based scientists working to develop and apply high-throughput approaches for detecting all sequence elements that confer biological function. The results of this pilot phase will guide future efforts to analyze the entire human genome.
Liquid entrainment from coalescence filter media—i.e. flow induced “blow-off” of previously deposited oil—in the form of droplets is poorly understood, for one because the generated spectrum is very ...wide and difficult to characterize with temporal and size resolution, especially for very large drops which carry most of the mass. Such filters operate at much lower flow rates than classical demisters, often in vertical orientation, with much finer geometries, and gravity plays no direct role for entrainment. We present a novel combination of four measurement techniques used to capture the entrained oil drop spectrum from filters during operation in the size range of 0.01–2400µm. The diameter range below 10μm combines two established real-time methods including an electrical mobility particle spectrometer (EMPS; <1μm) and an optical particle counter (OPC; 0.3 to 10μm). The diameter range above 170μm is covered by a newly developed “large drop detection system” (LDDS) based on single particle light scattering. OPC and LDDS continuously count and classify all drops originating from the entire filter coupon with a time resolution of 1min. The EMPS was operated intermittently, following brief switches from aerosol to clear air flow. Drops in the size range between OPC and LDDS were collected and sized by an off-line method.
This measuring system was applied to two representative types of glass microfiber media operated with oil mist generated from compressor oil, in order to characterize time resolved drop formation rates and spectra in the range of nanometers to millimeters. Wettable and non-wettable filter media were found to show similar entrainment characteristics, each with multi-modal drop spectra having two pronounced peaks in the ranges of 1–2μm and 200–300μm, respectively. During steady-state operation both modes were generated quasi-continually, the large drops at the rate of a few drops per hour and cm2 of filter surface, the micron size drops 103–104 times more frequently. Available indirect evidence suggests the same underlying entrainment mechanism for both types of fibrous media, namely the break-up of air bubbles formed periodically on the oil that drains on the downstream filter face. Direct detachment (blow-off) of large drops is unlikely at the prevailing operating conditions.
•Drop spectra from nm to mm were recorded in real time for filters in operation.•Oil drop spectra were bi-modal with peaks at 1–2μm and 200–300μm.•Spectra and rates were similar for wettable and non-wettable media.•Entrained drops are most likely the fragments of bursting bubbles.
The study focused on the assessment of the performance of three WWTPs in Greece by the estimation of the microbiological and chemical quality of influent and effluent sewage. Physicochemical ...parameters were recorded (temperature, pH, COD, BOD, suspended solids, conductivity), and meteorological data were collected (air temperature, rain). Microbiological parameters were analyzed (Escherichia coli, total coliforms, bacteriophages, Salmonella, human adenoviruses, Candida, Pseudallescheria boydii, helminths, parasites Cryptosporidium ssp., and Giardia spp.). Statistically significant correlations among the various aforementioned parameters were investigated, in an attempt to propose appropriate processing performance indicators. Furthermore, the study aimed to assess current joint ministerial decision (JMD) on wastewater reuse, for irrigation purposes; to evaluate its practicability and its potential for public health protection. In the vast majority, outlet samples from all three studied WWTPs were not appropriate for irrigation reuse purposes based on BOD₅₀ and suspended solids limit values, set by the current JMD, for both limited and unrestricted irrigation applications. Reductions for E. coli, total coliforms, and bacteriophages were found to range between 2–3, 1.5–2.5, and 2–4 log₁₀ values, respectively. Salmonella spp. was detected in outlet sewage samples from Patra (PAT), Arachova (ARH), and Livadeia (LEV), at 23 % (3/13), 33 % (4/12), and 38 % (5/13), respectively. Molds were detected at 92.3 % (12/13), 100 % (13/13), and 91.6 % (11/12), respectively, while Candida was found at 85 % (11/13), 67 % (8/12), and 46 % (6/13). A high prevalence of Pseudallescheria boydii, in outlet samples from all studied WWTPs is an important public health issue, which underlines the need for further studies on this emerging fungal pathogen in wastewater reuse applications. Pseudallescheria boydii was found at 85 % (11/13), 67 % (8/12), and 46 % (6/13), respectively. Helminths were found in both inlet and outlet samples, of all studied WWTPs, at 100 %. Human adenoviruses, were detected at high percentages in outlet samples at 76.9 % (10/13), 92.3 % (12/13), 84.6 % (11/13), respectively, while no influence of UV irradiation was recorded on the entry and exit loads of human adenoviruses. No influence of meteorological parameters was found on the microbiological and chemical parameters, with the exception of a weak positive correlation between environmental temperature and bacteriophages. A moderate positive correlation was found between BOD and suspended solids, bacteriophages, and total coliforms, bacteriophages and E. coli, and bacteriophages and adenoviruses. A significant positive correlation was found between total coliforms and E. coli, COD and BOD, and suspended solids and COD. No correlations were proved between human pathogens and bacterial indicator parameters. Collectively, our findings underlined the unsuitability of the current JMD on wastewater reuse in Greece, or public health protection. The study is expected to support the development of a public health risk assessment model based on quantitative risk assessment on the use of treated wastewater for irrigation purposes in Greece.
Many factors govern conditioning effectiveness, including the intertrial interval (ITI) used during training. The present study systematically varied the training ITI during both trace and long-delay ...fear conditioning. Rats were trained using one of six different ITIs and subsequently tested for conditioning to the white noise conditioned stimulus (CS) and the training context. After trace conditioning, percent freezing to the CS was positively correlated with training ITI, whereas percent freezing to the context was negatively correlated with training ITI. In contrast, when rats were trained using a long-delay paradigm, freezing during the CS test session did not vary as a function of training ITI; rats exhibited robust freezing at all ITIs. The long-delay conditioned rats exhibited relatively low levels of freezing during the context test. Thus, trace is more sensitive than long-delay fear conditioning to variations in the training ITI. These data suggest that training ITI is an important variable to consider when evaluating age or treatment effects, where the optimal ITI may vary with advancing age or pharmacological treatment.
Using high-density oligonucleotide arrays representing essentially all nonrepetitive sequences on human chromosomes 21 and 22, we map the binding sites in vivo for three DNA binding transcription ...factors, Sp1, cMyc, and p53, in an unbiased manner. This mapping reveals an unexpectedly large number of transcription factor binding site (TFBS) regions, with a minimal estimate of 12,000 for Sp1, 25,000 for cMyc, and 1600 for p53 when extrapolated to the full genome. Only 22% of these TFBS regions are located at the 5′ termini of protein-coding genes while 36% lie within or immediately 3′ to well-characterized genes and are significantly correlated with noncoding RNAs. A significant number of these noncoding RNAs are regulated in response to retinoic acid, and overlapping pairs of protein-coding and noncoding RNAs are often coregulated. Thus, the human genome contains roughly comparable numbers of protein-coding and noncoding genes that are bound by common transcription factors and regulated by common environmental signals.
In this report, we have achieved a richer view of the transcriptome for Chromosomes 21 and 22 by using high-density oligonucleotide arrays on cytosolic poly(A)(+) RNA. Conservatively, only 31.4% of ...the observed transcribed nucleotides correspond to well-annotated genes, whereas an additional 4.8% and 14.7% correspond to mRNAs and ESTs, respectively. Approximately 85% of the known exons were detected, and up to 21% of known genes have only a single isoform based on exon-skipping alternative expression. Overall, the expression of the well-characterized exons falls predominately into two categories, uniquely or ubiquitously expressed with an identifiable proportion of antisense transcripts. The remaining observed transcription (49.0%) was outside of any known annotation. These novel transcripts appear to be more cell-line-specific and have lower and less variation in expression than the well-characterized genes. Novel transcripts were further characterized based on their distance to annotations, transcript size, coding capacity, and identification as antisense to intronic sequences. By RT-PCR, 126 novel transcripts were independently verified, resulting in a 65% verification rate. These observations strongly support the argument for a re-evaluation of the total number of human genes and an alternative term for "gene" to encompass these growing, novel classes of RNA transcripts in the human genome.
Antimicrobials are the most frequently prescribed drug in pediatrics, with an estimated 37% of infants and 61% of hospitalized children having received them. Approximately 20–50% of prescriptions ...have been shown to be potentially unnecessary or inappropriate. The World Health Organization (WHO) estimates that the continued increase in antimicrobial resistance by the year 2050 will lead to the death of 10 million people per year. This paper describes a protocol to be used in a future study to evaluate the implementation of a quarterly syndromic antibiogram, aimed to improve the use of antibiotics for the treatment of pediatric bacterial infections at the Maputo Central Hospital, Mozambique. This study uses implementation science methods framed by the Dynamic Adaption Process (DAP) and RE-AIM conceptual frameworks to develop a multi-phase, mixed-methods evaluation utilizing qualitative and quantitative approaches. The pediatric inpatient services at HCM consist of approximately 18 physicians and 60 nurses. Additionally, the microbiology laboratory consists of eight laboratory technicians. We anticipate analyzing approximately 9,000 medical records. Qualitative methods include in-depth interviews with clinicians, laboratory technicians, and administrators to explore current knowledge and practices around antibiotic decision making, facilitators and barriers to intervention implementation, as well as acceptability and satisfaction with the intervention roll-out. Qualitative analysis will be performed with NVivo 12 software. Quantitative methods include extracting data from existing records from the pediatric ward of Hospital Central de Maputo (HCM) guided by the RE-AIM framework to explore intervention utilization and other factors influencing its implementation. Quantitative descriptive and inferential statistical analysis will be performed using R Studio statistical software. The findings from this evaluation will be shared with hospital administrators and relevant national policymakers and may be used by the Ministry of Health in deciding to expand this approach to other hospitals. The expected results of this research include the development of standard operating guidelines for the creation, distribution, and use of a quarterly syndromic antibiogram for antibiotic decision making that is informed by local epidemiology. Findings from this study will be used to develop a larger multi-site trial in Mozambique.
Purpose Low radiation doses and potentially inaccurate recall of the number of past x-ray examinations have hampered designing informative studies of cancer risk associated with medical radiation ...exposure. We investigated whether cumulative exposure from personal diagnostic x-rays was associated with increased frequencies of chromosome translocations among radiologic technologists because they may recall past radiographic procedures better than the general public. Methods 150 U. S. radiologic technologists who began working before 1950 were selected for blood collection and telephone interview, including past x-ray examinations. The number of and the examination types were converted to a radiation dose score with units that were an approximation of cGy. For each study subject, the frequencies of translocations were identified by whole chromosome painting. A linear Poisson regression model was used to assess the relationship between radiation dose score and translocation frequency. Results After adjustment for age, translocation frequencies increased with increasing diagnostic RBM dose score with an estimate of 0.04 translocations per 100 CEs per unit RBM score (95% CI, 0.02 to 0.07; P=0.003). Adjustment for gender, cigarette smoking, occupational radiation dose, allowing practice x-rays while training, work with radioisotopes, and radiotherapy for benign conditions did not materially affect the slope estimate. Conclusions Cumulative radiation exposure from routine x-ray examinations was associated with increased numbers of chromosome translocations. While the enormous benefit of radiation in disease diagnosis and patient treatment remains unquestioned, potential long-term chromosome damage and other associated health risks argue against excess use or unnecessary repeats of diagnostic x-ray examinations.
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