Efficiency Of Screens Research Articles

Influence of the mechanical characteristics of harp screen material on screening process

The paper presents the results of studies on the influence of mechanical characteristics of harp screen material on the technological parameters of screening. A mathematical model of the vibrational process of harp screens is presented depending on the length of their free areas, magnitude of technological load and characteristics of the screened material. Dependences of the relative vibrations amplitudes of rubber and cable strips on the length of their free areas are determined for different values of process load. As a result of the researches, it was established that the amplitude of the relative vibration of rubber strip under load decreases with increasing length of their free areas and for steel cable strips it increases, reaching a maximum at certain values of process load. It was also found that presence of the load dramatically reduces the amplitude of relative vibration of rubber strips, especially, in the area of dimensionless frequencies of the order of (0.6 – 1.4)g, while the vibrations amplitude of cable strips vary slightly in this frequency range. The article presents information on rubber-cable harp screening surfaces of mesh type: strips in the form of steel cables, rubberized with rubber cover having lateral separation projections. The use of rubber-cable strips as working elements of the screening surface allows to increase the “open area” of the screen due to the increase of distance between supports while maintaining high and stable amplitude of strips vibrations. Optimization of mechanical characteristics of the working elements material of harp screens and conditions of their fixation allows to intensify separation of screened material into fractions by eliminating sticking of the screened surface with clay particles and clogging of the material with “difficult” grains, and to improve significantly technical and economic indicators of the screening process. Such screening surface passed successful industrial tests at a number of quarries producing construction aggregates for the separation of crushed stone and gravel. Economic efficiency of the rubber-cable harp screens is presented in comparison with the wire screens in technological schemes of processing of mineral raw materials.

Effect of particle cohesion on flow and separation in industrial vibrating screens

Screens are often used to separate large volumes of granular materials according to size. Discrete Element Method (DEM) modelling using non-spherical particle representations has previously provided increased understanding of the operation of such industrial screens operating both wet and dry. If a granular material has any combination of moderate amounts of water or clay present then it can become sticky which then affects its flow properties. We examine the influence of inter-particle cohesion on flow through and separation efficiency of such screens using a DEM model that includes a simple representation of the cohesive force. For high levels of cohesion the stickiness of the bulk material prevents proper flow through the machine with material building up in the rock box and then overflowing its back. For intermediate cohesion levels the material behaviour changes rapidly from sticky and difficult to flow to one for which particles can be properly processed by the screen. For lower cohesion levels the screen separation performance becomes independent of the level of cohesion level and behaves as if the material is cohesionless.

Applications of the discrete element method and Fibonacci sequence on a banana screen

PurposeThe purpose of this paper is to design the geometrical structure of banana screen, and this study aims to improve the screen efficiency.Design/methodology/approachThe discrete element method was used to simulate the sieving process of banana screen with the inclinations of decks improved by Fibonacci sequence. The effect of each deck along screen length on the screening efficiency of particles was studied in this paper.FindingsThe comparisons among three groups of industrial banana screens with five different consecutive Fibonacci numbers have been made, and the variations of fine particle ratio were also investigated. The results show that the banana screening improved by the 5 Fibonacci sequence, 3, 5, 8, 13 and 21, has the good screening performance in the simulation. It is found that the inclination degree of the first deck at the feed end is the key factor to determine screening efficiency of banana screens.Practical implicationsIt is not possible to consider all real physical factors exactly in a virtual model. The experiment prototype of banana screen was used to simply verify the feasibility of the methodology.Originality/valueThis work is helpful for designing the geometric parameters of the curved screen and gives a broad perspective to improve the efficiency of banana screens.

Screen Efficiency and Implications for Losses of Lamprey Macrophthalmia at California's Largest Water Diversions

AbstractWe investigated the guidance efficiency of fish screens for the protection of emigrating Pacific Lamprey Entosphenus tridentatus and Western River Lamprey (also known as River Lamprey) Lampetra ayresii in a series of experimental trials. All trials were conducted at the Tracy Fish Collection Facility, located in the Sacramento–San Joaquin River Estuary at the entrance to one of the world's largest surface water diversions. Using 1,200 lamprey macrophthalmia, we tested for the effect of screen type, time of day, and channel water velocity to guide their swimming behavior to avoid entrainment. We found overwhelming evidence for an effect of screen type on efficiency, whereby all lampreys were successfully guided to a holding tank when a vertical traveling screen was used. This was likely due to the small pore size of the screen relative to lamprey sizes. In contrast, the efficiency of louvers, a behavioral screen designed for salmonids, varied by the interaction of time of day and channel velocity. During nighttime, when lamprey typically emigrate, louver guidance efficiency ranged from 21% (95% CI, 14–30%) to 24% (95% CI, 16–34%). These results were applied to estimate the probability for salvage of lamprey macrophthalmia at the Tracy Fish Collection Facility, which includes a two‐stage fish screen design. Between 1957 and 2014, we estimated that 94–96% of the lampreys that were entrained in the export flows were lost and not returned to the delta. However, the probability for fish loss was reduced in 2014 when the secondary louver was replaced with a vertical traveling screen. Our results suggest that lamprey macrophthalmia entrainment into the canals will be eliminated at the Tracy Fish Collection Facility if the primary screen is converted to vertical traveling screen. Surface water diversions may represent a substantial threat to regional metapopulations of anadromous lamprey species worldwide, and screening approaches applied to other fish species such as salmonids may not be protective of lampreys.Received June 7, 2016; accepted August 23, 2016Published online December 20, 2016

Zebrafish embryonic development is induced by carp sperm

Haploid gynogenetic screens increase the efficiency of forward genetic screens and linkage analysis in fish. Typically, UV-irradiated zebrafish sperm is used to activate zebrafish oocytes for haploid screens. We describe the use of UV-irradiated common carp sperm to activate haploid gynogenetic zebrafish development. Carp × zebrafish hybrids are shown to have a characteristic set of features during embryonic development and exhibit functional development of several tissues (muscle, heart and nervous system). Hybrids become inviable past the embryonic stages. This technique eliminates the possibility of incompletely irradiated zebrafish spermatozoa contaminating haploid progenies. While developing this protocol, one unique zebrafish female was identified which, upon insemination with UV-irradiated carp spermatozoa, repeatedly displayed spontaneous diploidization of the maternal chromosomes in her offspring.

Improving the Efficiency of Screens with a Linear Electromagnetic Motor

Results are reported from studies undertaken to improve the efficiency of screens that are equipped with linear electromagnetic motors and undergo low-frequency resonance during service. The article substantiates the indices that were found to characterize the efficiency of the screens and the improvement made in the design of their main component – the vibration exciter. An efficient size was determined for the air gap in the motors.

Improving drug discovery with high-content phenotypic screens by systematic selection of reporter cell lines.

High-content, image-based screens enable the identification of compounds that induce cellular responses similar to those of known drugs but through different chemical structures or targets. A central challenge in designing phenotypic screens is choosing suitable imaging biomarkers. Here we present a method for systematically identifying optimal reporter cell lines for annotating compound libraries (ORACLs), whose phenotypic profiles most accurately classify a training set of known drugs. We generate a library of fluorescently tagged reporter cell lines, and let analytical criteria determine which among them—the ORACL—best classifies compounds into multiple, diverse drug classes. We demonstrate that an ORACL can functionally annotate large compound libraries across diverse drug classes in a single-pass screen and confirm high prediction accuracy via orthogonal, secondary validation assays. Our approach will increase the efficiency, scale and accuracy of phenotypic screens by maximizing their discriminatory power.

The modelling of desk screens by a combined BEM – Source image approach

An original BEM approach is proposed to study the efficiency of desk screens in open plan offices. For large offices the volume geometry can be approximated by two horizontal planes – for floor and ceiling – and the source image approach is used to compute an approximated room Green function. When used in combination with the BEM approach, this allows reducing the discretised boundary to the desks only. The computation of the room Green functions is based on the modelling of the floor and ceiling response by means of the image source approach. The proposed approach is validated both numerically and experimentally. Very significant reductions of computation times have been obtained. The approach is used in an attempt to design efficient desk screens.

Defined PEG smears as an alternative approach to enhance the search for crystallization conditions and crystal-quality improvement in reduced screens.

The quest for an optimal limited set of effective crystallization conditions remains a challenge in macromolecular crystallography, an issue that is complicated by the large number of chemicals which have been deemed to be suitable for promoting crystal growth. The lack of rational approaches towards the selection of successful chemical space and representative combinations has led to significant overlapping conditions, which are currently present in a multitude of commercially available crystallization screens. Here, an alternative approach to the sampling of widely used PEG precipitants is suggested through the use of PEG smears, which are mixtures of different PEGs with a requirement of either neutral or cooperatively positive effects of each component on crystal growth. Four newly defined smears were classified by molecular-weight groups and enabled the preservation of specific properties related to different polymer sizes. These smears not only allowed a wide coverage of properties of these polymers, but also reduced PEG variables, enabling greater sampling of other parameters such as buffers and additives. The efficiency of the smear-based screens was evaluated on more than 220 diverse recombinant human proteins, which overall revealed a good initial crystallization success rate of nearly 50%. In addition, in several cases successful crystallizations were only obtained using PEG smears, while various commercial screens failed to yield crystals. The defined smears therefore offer an alternative approach towards PEG sampling, which will benefit the design of crystallization screens sampling a wide chemical space of this key precipitant.

Measurement of the secondary electron emission from CVD diamond films using phosphor screen detectors

Diamond-based photomultipliers have the potential to provide a significant improvement over existing devices due to diamond's high secondary electron yield and narrow energy distribution of secondary electrons which improves energy resolution creating extremely fast response times. In this paper we describe an experimental apparatus designed to study secondary electron emission from diamond membranes only 400 nm thick, observed in reflection and transmission configurations. The setup consists of a system of calibrated P22 green phosphor screens acting as radiation converters which are used in combination with photomultiplier tubes to acquire secondary emission yield data from the diamond samples. The superior signal voltage sampling of the phosphor screen setup compared with traditional Faraday Cup detection allows the variation in the secondary electron yield across the sample to be visualised, allowing spatial distributions to be obtained. Preliminary reflection and transmission yield data are presented as a function of primary electron energy for selected CVD diamond films and membranes. Reflection data were also obtained from the same sample set using a Faraday Cup detector setup. In general, the curves for secondary electron yield versus primary energy for both measurement setups were comparable. On average a 15–20% lower signal was recorded on our setup compared to the Faraday Cup, which was attributed to the lower photoluminescent efficiency of the P22 phosphor screens when operated at sub-kilovolt bias voltages.

Large-scale shielding structures in low earth orbits

The problems involved in the design-engineering digital simulation of large-size transformable-screen constructions for protecting spacecraft and equipment from space debris and meteoroids were considered. The engineering principles used to improve the design and efficiency of protective screens are presented. The use of embedded matrix transducers located all over the composite material used for armor tiles is proposed for the construction of protective clad screens; this approach enables efficient detection of damaged areas of the protective screen, the assessment of the level of damage, and the prediction of damage to spacecraft and equipment structures.

Editorial: mining for pharmacophores in phenotypic screens.

Let's consider the growing popularity of phenotypic screens within the drug development community. Biochemical assays once dominated the field of high throughput chemical screening, but phenotypic experiments are more adept at modeling real physiological behavior, and can simultaneously mimic drug delivery factors including cell membrane permeability, intracellular localization, and aspects of transport and metabolism. Efficiency and cost of phenotypic screens have improved substantially over the years. For all of these reasons, the technology is well suited to fostering lead optimization. The technology has disadvantages, however, in that data complexity hinders de novo SAR rationalization. For preliminary screens over diverse chemotypes, the simpler biochemical construct affords a good platform for classifying hits according to target-specific modulation, thus facilitating systematic pharmacophore perception. With phenotypic screens, activity trends across different chemotypes may actually reflect modulation of different biochemical targets or via distinct interaction modes. Even within the same chemotype family, pharmacophore perception may be occluded by imprecise partitioning of observed bioactivity measurements between fundamental biochemical modulation versus variation across ADME-like factors. So the question arises: can phenotypic screens ultimately support systematic SAR-driven pharmacophore perception and thus fully supplant biochemical screens? The answer may be computational in nature: given a large, accurate phenotypic data set, one should theoretically be able to sort through the various influences to distill a reliable chemotype-specific SAR that distinguishes targetspecific trends from deliverability issues. This can be achieved via data mining. Unfortunately, many people who realize that data mining is designed for such challenges may be missing background insight that is key to exploiting such methods. Most often overlooked is the fact that excellent calculations will rarely rescue weak data. Grasping pharmacophore effects from a screening study requires data sets that are strategically sensitive to variations in molecular effects that dictate physiology. In order for a given chemical to exert specific biochemical activity, it must have the right solubility profile to be available to those biomolecules that must collectively admit, transport and bind the modulator in order to effect applicable bioactivity. Ligand solubility is determined by chemical substructures. Furthermore, every relevant intermolecular interaction is directly influenced by ligand chemical composition. Thus, if one knows which chemical substructures balance appropriate solubility with the interactions required to reach and bind the biomolecular target, one should be able to predict ligand activity. This is the essence of rational drug design and is, furthermore, the type of insight that careful mining of a well crafted data set should yield. A thorough discourse on 'careful' data mining, would take up much more than the space available to an editorial like this, but of more immediate interest to non-informaticians who design chemical screens would be a quick synopsis of what well crafted data sets might look like. To a significant extent, the data set will depend on whether one is trying to refine one's knowledge of the target specific SAR in a system, or if one is searching de novo for promising new chemotypes with activity toward a given phenotype. Ultimately, the strategy lies in giving the informatician the right spread of data to partition the global bioactivity measurement into contributing factors. In the simpler case where a chemotype family of interest has already been identified, the set of compounds screened should focus on chemicals with the desired core scaffold (or close variants thereof) so that subsequent data analysis will be emphasize SAR within that family and avoid informational contamination from other mechanisms of action. However, it can help to retain a small population of compounds derived from chemical families that likely act via distinct mechanisms; this enables computational differentiation not only between chemical properties that influence whether a given compound is active, but also perception of attributes that push modulators toward one mechanism over another. Secondly, although it may seem counter-intuitive to populate your screen with compounds known to have marginal solubility, membrane permeability or transport efficacy, a data set that includes them will also produce analysis that can distinguish molecular properties that favor target-specific interactions, versus those that amplify bioactivity simply by ensuring greater compound availability to the target. For speculative preliminary studies, systematic screening set selection reflects other considerations. Unlike targeted screening, the useful information from general preliminary screens is enhanced by embracing broad chemical functionality to reduce the number of potentially relevant chemotypes that are overlooked. Preliminary screens should also rigorously eschew compounds with poor ADME properties, since at this early stage there is little benefit in degrading chemotype-specific assessments with inactivity arising from factors other than target-compatibility. Resulting SAR analysis may blend factors that reflect target-specific effects with deliverability, but at least will lay a solid foundation for subsequent targeted lead discovery and refinement studies.

Identification of PLP2 and RAB5C as novel TPD52 binding partners through yeast two-hybrid screening

Tumor protein D52 (TPD52) is overexpressed in different cancers, but its molecular functions are poorly defined. A large, low-stringency yeast two-hybrid screen using full-length TPD52 bait identified known partners (TPD52, TPD52L1, TPD52L2, MAL2) and four other preys that reproducibly bound TPD52 and TPD52L1 baits (PLP2, RAB5C, GOLGA5, YIF1A). PLP2 and RAB5 interactions with TPD52 were confirmed in pull down assays, with interaction domain mapping experiments indicating that both proteins interact with a novel binding region of TPD52. This study provides insights into TPD52 functions, and ways to maximise the efficiency of low-stringency yeast two-hybrid screens.

Laboratory Verifying of Injection Screens Efficiency

Nowadays is method of creating additional hydroinsulaitng injection screen in wet masonry quite widespread in Europe and also the rest of the world. The biggest advantages of this progressive method is fast and inexpensive application during which no harm to the construction is caused. Meaning, that damaging of buildings statics is not really possible. Final goal of this paper is to describe application and experimental testing of final efficiency of injection screens.

Identification of compounds from the plant species Alepidea amatymbica active against HIV

As Alepidea amatymbica is commonly used and accepted as medicinal plant in South Africa for various indications, the scientific basis of its anecdotally described, putative anti-HIV properties was investigated. To this aim, we used an accelerated extraction–purification approach; extracts and therein sub-fractions of A. amatymbica were assessed in a cell-based assay targeting the replication of prototypic CXCR4-tropic (NL4-3) or CCR5-tropic (NL-AD87) HIV-1 strains.Sub-fractions of the extracts were generated through semi-preparative high performance liquid chromatography (HPLC) fractionation into triplicates of 96-well microtitre plates; they were then separately subjected to biological analysis and ultra performance liquid chromatography (UPLC) time-of-flight (TOF) analysis. A correlation plot was generated between the biological and chemical data to identify the biologically active compounds in those fractions that showed significant selective anti-HIV activity. The results indicated that rosmarinic acid was present in the wells that showed promising anti-HIV activity in vitro indicating that this compound is at least in part responsible for the antiviral properties of the A. amatymbica extracts. However, compared to standard retroviral inhibitor the anti-HIV activity of the pure compound was found to be only quite moderate. Nevertheless, the accelerated approach described herein increases the efficiency of screens towards identifying drug candidates much earlier in the discovery stage.

Measurement of acoustic properties of noise protection screen in Kharkov

The article considers the question of measurement of the efficiency of noise protection screen, the impact of traffic noise on human health, the analysis of the theoretical calculations and experimental data. On the basis of theoretical calculations and experimental data we suggested the methods of improvement of noise protection properties of screens. The acoustic ecology research is important, because on the basis of such measurements it is possible to map the noise of the city, to mark out the areas with high sound pressure, which need to be secured against such a harmful influence; and areas with a low sound pressure, the so-called quiet zones - the most favorable for recreation and life. There are a lot of works and researches on the harmful effects of noise. The data presented in the article show the efficiency of noise protection screens in urban areas and along highways

Development and Dosimetry of a Small Animal Lung Irradiation Platform

Advances in large scale screening of medical countermeasures for radiation-induced normal tissue toxicity are currently hampered by animal irradiation paradigms that are both inefficient and highly variable among institutions. Here, a novel high-throughput small animal irradiation platform is introduced for use in orthovoltage small animal irradiators. Radiochromic film and metal oxide semiconductor field effect transistor detectors were used to examine several parameters, including 2D field uniformity, dose rate consistency, and shielding transmission. The authors posit that this setup will improve efficiency of drug screens by allowing for simultaneous targeted irradiation of multiple animals to improve efficiency within a single institution. Additionally, they suggest that measurement of the described parameters in all centers conducting countermeasure studies will improve the translatability of findings among institutions. The use of tissue equivalent phantoms in performing dosimetry measurements for small animal irradiation experiments was also investigated. Though these phantoms are commonly used in dosimetry, the authors recorded a significant difference in both the entrance and target tissue dose rates between euthanized rats and mice with implanted detectors and the corresponding phantom measurement. This suggests that measurements using these phantoms may not provide accurate dosimetry for in vivo experiments. Based on these measurements, the authors propose that this small animal irradiation platform can increase the capacity of animal studies by allowing for more efficient animal irradiation. They also suggest that researchers fully characterize the parameters of whatever radiation setup is in use in order to facilitate better comparison among institutions.

An Examination of the Diagnostic Efficiency of Post‐Deployment Mental Health Screens

To conduct a blinded study to examine the diagnostic efficiency of the Department of Defense (DoD) Post-Deployment Health Reassessment (PDHRA) screens for major depressive disorder (MDD), posttraumatic stress disorder (PTSD), and alcohol abuse. Participants were 148 post-deployed soldiers who were completing the PDHRA protocol. Soldiers' mean age was 27.7 (standard deviation= 6.6) years, and 89.0% were male. Mental health professionals blinded to the PDHRA screening results administered the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition directly after the PDHRA assessment protocol. All screens exhibited excellent negative predictive power. Sensitivity metrics were lower, consistent with the relatively low base rates observed for MDD (10.1%), PTSD (8.8%), and alcohol abuse (5.4%). Metrics obtained for the PTSD screen were consistent with previous research with a similar base rate. A two-item screen containing PTSD reexperiencing and hyperarousal symptom items revealed excellent psychometric properties (sensitivity= .92; specificity= .79). The alcohol abuse screen yielded high sensitivity (.86), but very poor precision; these metrics were somewhat improved when the screen was reduced to a single item. The PDHRA MDD, PTSD, and alcohol abuse screens appear to be functioning well in accurately ruling out these diagnoses, consistent with a population-level screening program. Cross validation of the current results is indicated. Additional refinement may yield more sensitive screening measures within constraints imposed by the low base rates in a typically healthy population.

Ammonia-nitrogen and orthophosphate removal by immobilized Chlorella sp. isolated from municipal wastewater for potential use in tertiary treatment

Chlorella sp. isolated from municipal wastewater and entrapped in calcium alginate as algal sheets was employed to remove inorganic nutrients from domestic secondary effluents in parallel-plate bioreactor after starvation. The key factors affecting the nutrient removal efficiency, system stability and reuse efficiency of screens were discussed. The results show that cell density and starvation time significantly affected the nutrient uptake. A complete removal of NH 4 + -N and PO 4 3- -P was achieved within 4 h of treatment with the optimal cell density in the mixture of algal and 3 mm gel sheets after third cycle. Six cycles of wastewater treatment were accomplished in 18 days, achieving higher removal efficiency. NH 4 + -N removal efficiency was 81% after 1.25 h and 98.81% after 4 h, while PO 4 3- -P removal efficiency was 77.4% after 1.25 h and 100% after 4 h. It was confirmed that the immobilized Chlorella sp. has great potentialities in nutrient removal. Key words: Immobilized Chlorella, starvation, wastewater treatment, nitrogen removal, phosphorus removal.

Calculation of the quantum efficiency of phosphor screens in CRTs and FL tubes

The quantum efficiencies of CRT and FL tubes that use a phosphor screen as transducer of invisible particles to light in visible spectrum wavelengths were calculated in this study. The phosphor screens in CRT tubes have quantum efficiencies greater than 3,000, which give the luminance of comfortable images on phosphor devices for the observation by the eyes. The established FL tubes have the amazing quantum efficiency of 3×1010 photons per moving electron per FL tube, which allows the illumination of a 5×5 m2 room by three FL tubes, with heating at 40°C. Thus, FL tubes, including for backlighting of LCD displays, have a superior over other illumination sources.