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Journal articles on the topic "Tubes dilution. eng"
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De Simone, Nicole, and Ravi Sarode. "The Use of Activated Partial Thromboplastin Time As a Surrogate to Predict Residual FVIII Activity in the Bethesda Assay." Blood 128, no. 22 (2016): 4962. http://dx.doi.org/10.1182/blood.v128.22.4962.4962.
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Abstract Introduction: Bethesda assays, used in the quantification of factor VIII inhibitors, are time and labor intensive. They are performed by mixing one part of normal pooled plasma (NPP) with an equal amount of serial dilutions of patient plasma in imadizole buffered saline (IBS), and incubating at 37°C for 2 hours. After the incubation time, most laboratories perform factor VIII (FVIII) activities on each tube. These results are divided by the activity resulted on the control (NPP+IBS) to obtain the percent residual activity. The dilution with a percent residual FVIII activity between 25-75% is then converted to a Bethesda Unit using the Bethesda graph. This value is multiplied by the dilution to calculate final Bethesda units/mL. We propose an alternative method, involving performing partial thromboplastin times (PTTs) on all dilution tubes and only performing FVIII activity testing on a limited number of tubes e.g. 2 tubes rather than all 10 tubes. The study below describes the methodology and provides data to show how the PTT can be used as a surrogate. Using PTTs may reduce cost per test by reducing the amount of FVIII deficient plasma used for FVIII activity testing, especially in the case of very high titer inhibitors. Methods: Serial dilutions of patient plasma with IBS are prepared to the 512 dilution (10 tubes) and incubated with an equal amount of NPP along with a control consisting of IBS and NPP. PTTs are run using Siemens Actin FSL reagent on the BCS coagulometer (Siemens) on all 10 tubes and the control. The tube with a resultant PTT within 5 seconds above the control is identified and then that tube, along with the next higher dilution, are tested for residual factor VIII activity (ACL TOP, Instrumentation Laboratory). These results are used to calculate the percent residual FVIII activity and Bethesda units/mL as described above. To support our hypothesis, we performed PTT and FVIII activities on all dilution tubes. Results: We performed 14 inhibitor assays on 9 patients. 44% (4/9) had congenital hemophilia A with an inhibitor and 56% had acquired hemophilia A. Table 1 shows results from dilution tubes that resulted in residual FVIII activities between 25-75%. The dilutions with residual activity closest to 50% were used in the final interpretation and are bolded. Using the 5 seconds above control PTT to identify dilutions to limit FVIII assays correlated with residual FVIII activities in 12 of the 14 samples tested (86%). Furthermore, this method identified the dilution with the residual FVIII activities closest to 50% in 10 of the 12 samples. Two samples demonstrated no correlation between PTT and FVIII activities. These samples had low titer inhibitors (<5 BU), which could have been predicted by the low PTTs in the first two dilutions. In these cases, serial FVIII activities were used in calculations. More data is needed to definitively say whether this methodology could not be used for low titer inhibitors. Conclusion: An alternative method, using PTT testing to perform targeted FVIII activity testing, may be used in the Bethesda Assay. Table Table. Disclosures Sarode: CSL Behring: Consultancy, Honoraria.
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Arif, Ani Atul, Tulus Maulana, Ekayanti Mulyawati Kaiin, Bambang Purwantara, Raden Iis Arifiantini, and Erdogan Memili. "Comparative analysis of various step-dilution techniques on the quality of frozen Limousin bull semen." November-2020 13, no. 11 (2020): 2422–28. http://dx.doi.org/10.14202/vetworld.2020.2422-2428.
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Background and Aim: Indonesia has two National Artificial Insemination centers and 17 Regional Artificial Insemination Centers. The frozen semen production techniques differed between the centers, including the type of diluent and semen dilution technique. The aim of the research was to compare the quality of frozen Limousin bull semen diluted using different techniques. Materials and Methods: Semen was collected from three sexually mature Limousin bulls using an artificial vagina. Immediately after collection, the semen was evaluated macroscopically and microscopically. Semen that had >70% motile sperm and <20% sperm abnormality was divided into three tubes and diluted with skim milk-egg yolk (SMEY) using three different dilution techniques: One-step dilution (100% SMEY with 8% glycerol) at room temperature ([RT] 20°C until 25°C) two-step dilution (50% SMEY without glycerol at RT, stored at 5°C; and 50% SMEY with 16% glycerol after 1 h stored at 5°C); and three-step dilution (50% SMEY without glycerol at RT, stored at 5°C; and 50% SMEY with 16% glycerol added twice at 1 h and 1.5 h after being stored at 5°C). The diluted semen was loaded into 0.25 mL mini straws, equilibrated, and frozen using a freezing machine. Sperm motility, viability, membranes, DNA integrity, and concentrations of malondialdehyde (MDA) and aspartate aminotransferase (AST) enzymes were evaluated after thawing. Results: The results showed that there were no significant differences in sperm motility and DNA integrity between dilutions (p>0.05). However, sperm viability and membrane intactness of one-step dilutions were higher than those of three-step dilutions. The concentrations of MDA and AST enzymes of sperm in one-step dilutions were lower than those of three-step dilutions (p<0.05). Conclusion: It was concluded that the one-step-dilution technique was better than three-step dilution for cryopreservation of Limousin bull semen.
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D’Amato, Francesco, Silvia Viciani, Alessio Montori, et al. "Spectroscopic Techniques versus Pitot Tube for the Measurement of Flow Velocity in Narrow Ducts." Sensors 20, no. 24 (2020): 7349. http://dx.doi.org/10.3390/s20247349.
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In order to assess the limits and applicability of Pitot tubes for the measurement of flow velocity in narrow ducts, e.g., biomass burning plants, an optical, dual function device was implemented. This sensor, based on spectroscopic techniques, targets a trace gas, injected inside the stack either in bursts, or continuously, so performing transit time or dilution measurements. A comparison of the two optical techniques with respect to Pitot readings was carried out in different flow conditions (speed, temperature, gas composition). The results of the two optical measurements are in agreement with each other and fit quite well the theoretical simulation of the flow field, while the results of the Pitot measurements show a remarkable dependence on position and inclination of the Pitot tube with respect to the duct axis. The implications for the metrology of small combustors’ emissions are outlined.
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Shiwaku, K., Y. Chigusa, T. Kadosaka, and K. Kaneko. "Factors influencing development of free-living generations of Strongyloides stercoralis." Parasitology 97, no. 1 (1988): 129–38. http://dx.doi.org/10.1017/s0031182000066804.
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SUMMARYThe effects of duration of infection and of temperature and nourishment in cultures on development of free-living generations of Strongyloides stercoralis were studied quantitatively. Rhabditiform larvae, 228–353 μm long, were collected from infected dogs with or without prednisolone treatment using the Baermann apparatus. Cultures were carried out by the filter paper test-tube method under the following conditions: incubation temperature 15–40°C and faecal dilution 1:0–1:16. Rhabditiform larvae developed predominantly to free-living females at incubation temperatures of 15–30°C and low faecal dilutions, but filariform larvae appeared mainly under extreme conditions such as high temperature. Recovery rates of filariform larvae were inversely related to those of females. It was remarkable that high temperature, but not low faecal dilution, affected development of filariform larvae. Although the appearance of free-living males was constant in various environmental conditions, the present study indicated an increase in free-living males with the duration of infection. Thus, it seems that free-living males are already fixed as male in the egg stage, and potential female rhabditiform larvae differentiate into free-living females or filariform larvae depending on environmental factors. There is no marked difference in the development of rhabditiform larvae into filariform larvae in either the immunosuppressed dog or the intact dog.
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Bobev, S. G., J. Van Vaerenbergh, and M. Maes. "First Report of Dickeya dianthicola Causing Blackleg on Potato (Solanum tuberosum) in Bulgaria." Plant Disease 98, no. 2 (2014): 275. http://dx.doi.org/10.1094/pdis-02-13-0147-pdn.
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Potato (Solanum tuberosum) is an important and widespread crop in Bulgaria. A new disease was observed on a single potato plot (Plovdiv region) without a history of potato cultivation in the spring of 2011. Initially, single lower leaves wilted on recently emerged plants (approx. 15% incidence) with subsequent desiccation of the leaf margins. The wilting progressed over time and eventually the whole stem became desiccated. A blackleg-like necrosis was noticed at the stem base when symptomatic plants were uprooted. Most diseased stems remained green above ground but pith tissue was heavily macerated and some of the stems became hollow as the pith dried out. Mother tubers were partially or entirely macerated. In most cases, the decay was initiated from the stolon end. Bacterial strains were obtained from symptomatic stems and tubers by dilution plating on King's B medium. The strains produced indigoidin pigment and induced a hypersensitive response 24 h after infiltration into tobacco and Sedum hybridum leaves (2). The strains were identified as Dickeya spp. by the production of the PCR amplicon of the pectate lyase ADE gene cluster (3) and of the pectate lyase I gene (4). The partial sequence of the fliC PCR amplicon (1) of strain SB2589 (GenBank Accession No. KF442436) displayed 100% homology with four whole genome shotgun sequences of Dickeya dianthicola in GenBank. Pectinolytic activity was demonstrated by inoculation of surface disinfested potato tubers of cv. Kondor. Conical core tissue was removed at the apical end and 100 μl bacterial suspension (107 CFU in sterile 10 mM phosphate buffer) was deposited in the cavity. The cap was reattached to the tuber and immobilized by Parafilm. Positive control tubers were inoculated with D. dianthicola reference strain GBBC 2039 (LMG 25864) and negative control tubers were inoculated with sterile 10 mM phosphate buffer. All tubers were incubated for 48 h at 28°C under micro-aerobic conditions reducing the air pressure to 90 mb in a vacuum incubator. The D. dianthicola reference strain and Bulgarian strains produced maceration of tuber tissue. Maceration was not observed in the negative control tubers. Potato plants cv. Kondor were grown from minitubers in sandy soil in plastic nursery containers. The plants were inoculated by root drenching (one application of cell suspension at 109 CFU/liter) when the stems were 15 to 20 cm high (tuber initiation stage). Plants were incubated at 25 to 28°C with regular watering. Wilting symptoms developed within 10 days of inoculation, followed by necrosis of the pith. Strains obtained from the inoculated stems were confirmed as D. dianthicola as described above. Based on the disease symptoms, the cultural, molecular, and pathological features of the strains, we conclude that the disease was caused by D. dianthicola and to our knowledge this is the first report of the pathogen on potato in Bulgaria. Furthermore, this incident warrants further surveys of pectinolytic bacteria causing blackleg-like symptoms in potato crops in Bulgaria. References: (1) S. Diallo et al. Eur. J. Plant Pathol. 125:349, 2009. (2) Y-.A. Lee and C-.P. Yu. J. Microbiol. Methods 64:200, 2006. (3) A. Nassar et al. Appl. Environ. Microbiol. 62:2228, 1996. (4) J. Van Vaerenbergh et al. PLoS ONE 7(5):e35738, 2012.
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Kjelland, M. E., T. Stroud, H. E. Ayliffe, and G. Dittami. "178 PORTABLE AUTOMATED MICROFLUIDIC DEVICE FOR RAPID DETERMINATION OF SPERM COUNTS." Reproduction, Fertility and Development 26, no. 1 (2014): 203. http://dx.doi.org/10.1071/rdv26n1ab178.
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The primary objective of this research was to determine whether an automated electronic cell counter using microfluidic technology (Moxi Z) could be effective for determining sperm concentrations. Validation consisted of comparing frozen-thawed conventional bovine sperm counts using the Moxi Z to Coulter Z2 counter results. Specific goals were to determine (1) if the Moxi Z could count intact motile sperm, (2) if differences in media containing egg yolk lipids would affect counting, and (3) evaluate sample concentration requirements for Moxi Z accuracy. Cryopreserved straws (n = 20) of conventional bovine semen (Brangus), were obtained from Stroud Veterinary Embryo Services Inc. Straws were thawed (~30 s, 38°C) in a water bath, dried, and cut open. Semen was expelled into 15-mL conical tubes (BD Falcon) using a straw plunger. Thereafter, samples were centrifuged (400 × g, 10 min). The supernatant was removed and replaced with PBS (media 1) or Tris A semen extender (20% vol/vol egg yolk; media 2). Sperm samples exhibited ~70% motility for the experiments, based on subjective microscopy by placing 10-μL sample volumes on 25 × 75 × 1-mm microscope slides (#2951–001, Thermo Scientific, Waltham, MA, USA) with 24 × 50-mm #1.5 coverslips (#M6047–9, Baxter, McGraw Park, IL, USA) and viewing with a Axio Scope.A1 microscope (Zeiss, Thornwood, NY, USA) using 10× (M Plan Apo NIR, Mitutoyo Am, Aurora, IL, USA) and 40× (LD-Plan NeoFluor, Zeiss) lenses (i.e. 100–400×). The protocol for each sample was to establish an initial concentration of ~2.5 × 106 cells mL–1 and perform a serial dilution assay, using modified Hank's Balanced Salt Solution (Sigma, St. Louis, MO, USA). Counts (n = 3) for each dilution level (e.g. 1.0, 0.8, 0.6, 0.4, 0.2, 0.1, 0.05, 0.025) were made simultaneously on each instrument, Moxi Z (v3.6 OS, Orflo) and Coulter Z2 (Beckman Coulter, Fullerton, CA, USA). Data points were compared to linear fitted curves. The Moxi Z gated range was set at 2.88 to 6.54 μ to approximate the count range of the Z2 system (2.91–6.46 μ). The sperm samples provided similar results on both the Moxi Z and the Z2 instruments. Specifically, data for the 2 media using serial dilutions of the sperm samples were analysed, and the Moxi Z counts correlated well with the Z2 counts for media 1 (R2 > 0.9469) and media 2 (R2 > 0.9771). Overall the Moxi Z can provide rapid bovine sperm counts (<15 s) using small sample volumes. The degree of precision and accuracy depends strongly on proper gate setting and on the ability to reduce sample debris. Increased size resolution will be realised by future improvements to the Moxi Z signal processing (v 4.0), as well as by slowing the system flow rate; thereby improving cell peak discrimination. The portability of the Moxi Z may be an asset for field work and will be tested in future research. The data and dilution ranges herein demonstrate the utility of the Moxi Z for diluted conventional semen and lower dose concentrations, such as that of sexed semen.
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Loken, Michael R., Sung-Chao Chu, Wayne K. Fritschle, Dian-Kun Li, and Denise A. Wells. "Correcting Flow Cytometric Blast Counts for Blood Contamination in Bone Marrow Aspirates." Blood 110, no. 11 (2007): 4613. http://dx.doi.org/10.1182/blood.v110.11.4613.4613.
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Abstract An accurate blast count is pivotal in the diagnosis, classification and prognosis of patients with myelodysplasia. Blast counts in all previous classification schemes are based on morphologic assessment of marrow aspirates with a poor correlation to blast counts determined by flow cytometry. A significant problem in blast enumeration by flow cytometry is the variable hemodilution of the marrow during collection for flow cytometric analysis. Blast counts can vary depending on which aspirate tube is used for flow analysis, e.g., 2.4%, 1st 5ml tube; 0.62%, 2nd 5ml tube; 0.58% 3rd 5ml tube. Morphologists circumvent this problem by selecting a region for assessment close to a spicule with minimal blood dilution. Cell surface antigens can be used to distinguish mature cells found in blood as distinct from immature cells identified in marrow. CD16 intensity on neutrophils reaches a maximum at the band/segmented stage of development with a low coefficient of variation, thereby becoming a marker for mature myeloid forms. A simple method to distinguish immature from mature myeloid cells was developed to assess extent of blood contamination in marrow aspirates using a combination of CD16, CD13, and CD45. The average mature neutrophil content of a marrow was determined from phenotypically normal bone marrow biopsy specimens, assumed to have minimal blood contamination. The proportion of dimCD16 cells gated on the myeloid cells based on CD45 and right angle light scatter in 31 biopsy specimens was 82% (range 69–93, SD=6.2) (Figure 1). A value of 80% (rather than 82%) was used for the subsequent calculations to correct for the excess mature neutrophils found in an aspirate as compared to the biopsies (Corrected Blasts = [80 / % dim CD16 myeloid] x determined blast count). To test this hypothesis bone marrow aspirates were diluted with blood at different ratios to mimic blood marrow hemodilution. Blasts (defined as CD45 dim, low right angle light scatter, HLA-DR positive, CD11b negative) were determined for the various dilutions, then corrected based solely on the proportion of dim CD16 myeloid cells (Figure 2). A marrow from an MDS case was also diluted (1:5 v/v) with blood for comparison. The original marrow contained 80% dim CD16 myeloid cells with a blast count of 9.2%. After dilution, only 12% dim CD16 cells were detected with 1.1% blasts, however upon correction (6.67), the blast count was 7.3%, close to the original determination. This approach may provide for more standardization and consistency in the determination of blast counts in MDS marrow specimens using flow cytometric analysis. Figure 1, CD16 of marrow myeloid cells. Figure 1,. CD16 of marrow myeloid cells. Figure 2, Uncorrected/Corrected Blast Count Figure 2,. Uncorrected/Corrected Blast Count
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Emerson, David, and Craig L. Moyer. "Neutrophilic Fe-Oxidizing Bacteria Are Abundant at the Loihi Seamount Hydrothermal Vents and Play a Major Role in Fe Oxide Deposition." Applied and Environmental Microbiology 68, no. 6 (2002): 3085–93. http://dx.doi.org/10.1128/aem.68.6.3085-3093.2002.
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ABSTRACT A number of hydrothermal vent sites exist on the summit of the Loihi Seamount, a shield volcano that is part of the Hawaiian archipelago. The vents are 1,100 to 1,325 m below the surface and range in temperature from slightly above ambient (10°C) to high temperature (167°C). The vent fluid is characterized by high concentrations of CO2 (up to 17 mM) and Fe(II) (up to 268 μM), but there is a general paucity of H2S. Most of the vents are surrounded by microbial mats that have a gelatinous texture and are heavily encrusted with rust-colored Fe oxides. Visually, the Fe oxides appeared homogeneous. However, light microscopy revealed that the oxides had different morphologies, which fell into three classes: (i) sheaths, (ii) twisted or irregular filaments, and (iii) amorphous oxides. A morphological analysis of eight different samples indicated that the amorphous oxides were overall the most abundant; however, five sites had >50% sheaths and filamentous oxides. These latter morphologies are most likely the direct result of microbial deposition. Direct cell counts revealed that all of the oxides had abundant microbial populations associated with them, from 6.9 × 107 to 5.3 × 108 cells per ml of mat material. At most sites, end point dilution series for lithotrophic Fe oxidizers were successful out to dilutions of 10−6 and 10−7. A pure culture was obtained from a 10−7 dilution tube; this strain, JV-1, was an obligate, microaerophilic Fe oxidizer that grew at 25 to 30°C. A non-cultivation-based molecular approach with terminal-restriction fragment length polymorphism also indicated the common presence of Fe-oxidizing bacteria at Loihi. Together, these results indicate that Fe-oxidizing bacteria are common at the Loihi Seamount and probably play a major role in Fe oxidation. A review of the literature suggests that microbially mediated Fe oxidation at hydrothermal vents may be important globally.
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Khaeruddin, Khaeruddin, Raden Iis Arifiantini, Cece Sumantri, and Sri Darwati. "KUALITAS SPERMATOZOA AYAM PERANAKAN SENTUL DALAM PENGENCER RINGER LAKTAT KUNING TELUR DENGAN BERBAGAI MONOSAKARIDA (Quality of Sentul Crossbreed Chicken Spermatozoa in Ringer Lactate-Egg Yolk Diluents Supplemented with Various Monosaccharide)." Jurnal Kedokteran Hewan - Indonesian Journal of Veterinary Sciences 10, no. 2 (2016): 166–69. http://dx.doi.org/10.21157/j.ked.hewan.v10i2.5090.
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The aim of this study was to examine the preservation of sentul crossbreed chicken semen in ringer lactate egg yolk diluent supplemented with various monosaccharide. Semen was collected from three roosters using massage method. Immediately after collection, the semen was evaluated macroscopically and microscopically. Semen with more than 70% motility was divided into four tubes. Each of them diluted with ringer lactate egg yolk glucose (RLEYG), ringer lactate egg yolk fructose (RLEYF), ringer lactate egg yolk xylose (RLEYX) and ringer lactate egg yolk mannose (RLEYM). Semen was stored in refrigerator (5o C) for sixty hours and evaluated every twelve hours for spermatozoa motility and viability. Results showed that no significant difference (P>0.05) among diluents used on spermatozoa quality parameters after dilution and during preservation. Semen quality decrease during storage and at sixty hours of storage, the motility and viability of spermatozoa ranging from 48.33±2.56 to 55.42±2.26% and 58.59±2.87 to 64.83±2.42%, respectively. This research conclude that glucose, fructose, xylose and mannose can be used as energy source for roosters semen during preservation.
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Bhakta, Abhijit, Maitreyi Bandyopadhyay, Sayantan Dasgupta, Santanu Sen, Arun Kumar, and Utpal Kumar Biswas. "Effect of NaHS on carbonic anhydrase activity of human erythrocyte." Asian Journal of Medical Sciences 7, no. 3 (2016): 23–27. http://dx.doi.org/10.3126/ajms.v7i3.14047.
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Background: In contrast to its role as poison, hydrogen sulfide (H2S) is recently considered as a gaso-transmitter which mediates important physiologic functions in humans. Evidence is accumulating to demonstrate that inhibitors of H2S production or therapeutic H2S donor compounds exert significant effects in various experimental models. Carbonic anhydrases (CA) are a group of zinc-containing metalloenzymes that catalyse the reversible hydration of carbon dioxide. CAs activity in erythrocytes (CAI and CAII) has recently been observed to be associated with various pathological conditions especially in diabetes mellitus, hypertension and lipid disorders. Alteration of this enzyme activity has been reported by the effect of advanced glycation end products methylglyoxal and reduced glutathione. Aims and Objectives: As H2S, being a mediator of many physiological functions and synthesized in vivo, may affect functions of many intracellular proteins like carbonic anhydrase, the objective of this study is to find out if there is any change in the carbonic anhydrase activity under the effect of H2S- donor NaHS in dose dependant manner using RBC model in vitro.Materials and Methods: Blood sample was collected from forty (40) numbers of healthy volunteers of 18-40 years of in heparin containing vials and packed cells were prepared immediately by centrifugation The packed erythrocytes were washed three times with normal saline and diluted (1:10) with the normal saline. One ml each of diluted packed cells was taken in eight test tubes. Serial dilutions of NaHS (1to 250 µMol/L) was added to all the test tubes except for the first test tube where only normal saline was added and incubated at room temperature for one hour. Haemolysates was prepared from the erythrocytes with equal volume of distilled water in each tube and the CA activity was determined in the haemolysates using standardized method.Results: There is significant increase of CA activity in dose dependent manner under the effect of NaHS and also compared to the activity of hemolysate prepared without NaHS. Conclusions:Our study for the first time demonstrated that the Carbonic Anhydrase activity of erythrocytes is significantly increases by the effect of NaHS and this study reveals some important biological role of H2S and carbonic anhydrase.Asian Journal of Medical Sciences Vol. 7(3) 2016 23-27
Dissertations / Theses on the topic "Tubes dilution. eng"
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Moraes, Helen Pimenta de. "Avaliação in vitro da atividade antibacteriana de extratos de Byrsonima ssp E Alchornea ssp: estudo comparativo entre as técnicas de diluição em tubos e microplacas /." Araraquara : [s.n.], 2006. http://hdl.handle.net/11449/97904.
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Orientador: Taís Maria Bauab<br>Banca: Sérgio Aparecido Torres<br>Banca: Daisy Nakamura Sato<br>Resumo: O Brasil apresenta uma grande diversidade de plantas medicinais, cuja utilização pela população vem aumentando cada vez mais. Byrsonima (Malpighiaceae) e Alchornea (Euphorbiaceae) que são plantas do Bioma-Cerrado do estado de São Paulo apresentam compostos com grande potencial de atividade biológica, sendo entretanto, pouco estudadas. A atividade antimicrobiana é uma etapa de extrema importância na caracterização biológica de produtos naturais com potencial farmacológico. Nossos objetivos foram investigar a atividade antibacteriana de extratos metanólicos e clorofórmicos de Byrsonima spp. e Alchornea spp empregando as técnicas de diluição em tubos e em microplacas com leitura espectrofotométrica e visual utilizando resazurina como revelador. Foram utilizadas as bactérias: Escherechia coli, Staphylococcus aureus, Yersinia enterocolitica e Aeromonas hydrophila. Nos ensaios em microplacas e em tubos foi determinada a concentração inibitória mínima (CIM) dos extratos vegetais testados à concentração de 1000æg/mL a 31,25æg/mL. Objetivou-se também comparar a eficácia das metodologias empregadas. Nosso estudo demonstrou maior atividade antibacteriana dos extratos metanólicos tanto de Byrsonima quanto de Alchornea, ressaltando os dados obtidos com B. crassa (MeOH) e B. basiloba (MeOH) que apresentaram acentuada atividade antibacteriana frente aos diferentes microrganismos testados. As metodologias empregadas foram eficazes para essa finalidade sendo as de diluição em microplacas mais vantajosas, pelo emprego de pequenos volumes principalmente os de extratos vegetais que são obtidos em pequenas quantidades. Dentre os dois métodos de microdiluição, a que empregava leitura espectrofotométrica apresentou-se mais sensível, porém a de leitura visual mostrou-se mais prática na leitura final e na interpretação dos resultados.<br>Abstract: Brazil presents a great diversity of medicinal plants, whose use by people increases more and more. Byrsonima (Malpighiaceae) and Alchornea (Euphorbiaceae) are plants of Bioma-Cerrado of the state of São Paulo and present composites with great potential of biological activity, but, however, they are little studied. The antimicrobial activity is a stage of extreme importance in the biological characterization of natural products with pharmacological potential. Our objectives were to investigate the antibacterial activity of methanolic and chlorophormic extracts of Byrsonima spp and Alchornea spp using the techniques of dilution in tubes and in microplates with spectrophotometric and visual readings using resazurin. Escherichia coli, Staphylococcus aureus, Yersinia enterocolitica and Aeromonas hydrophila were tested. In the microplate and tubes assays, the minimum innhibitory concentration (MIC) of plant extracts were tested in concentrations between 1000æg/mL and 31.25æg/mL. It was also compared the effectiveness of the methodologies employed. Our study demonstrated greater antibacterial activity of methanolic extracts of both Byrsonima and Alchornea, standing out the data obtained for B. crassa (MeOH) and B. basiloba (MeOH), which presented accented antibacterial activity against the different tested microrganisms. The methodologies employed were efficient for this purpose and the microplate dilution assay is more advantageous, for the fact it uses smaller volumes, mainly for those vegetal extracts that normally are obtained in small amounts. Amongst the two methods of microdilution, the one that used spectrophotometric reading proved to be more sensitive, however, the visual reading procedure was shown to be more practical in the final reading and interpretation of the results.<br>Mestre
Conference papers on the topic "Tubes dilution. eng"
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Laich, Andrew R., Jessica Baker, Erik Ninnemann, et al. "Ignition Behavior of Oxy-Methane With High Fuel Loading and CO2 Dilution in a Shock Tube." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14338.
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Abstract Ignition delay times were measured for methane/O2 mixtures in a high dilution environment of either CO2 or N2 using a shock tube facility. Experiments were performed between 1044 K and 1356 K at pressures near 16 ± 2 atm. Test mixtures had an equivalence ratio of 1.0 with 16.67% CH4, 33.33% O2, and 50% diluent. Ignition delay times were measured using OH* emission and pressure time-histories. Data were compared to the predictions of two literature kinetic mechanisms (ARAMCO MECH 2.0 and GRI Mech 3.0). Most experiments showed inhomogeneous (mild) ignition which was deduced from five time-of-arrival pressure transducers placed along the driven section of the shock tube. Further analysis included determination of blast wave velocities and locations away from the end wall of initial detonations. Blast velocities were 60–80% of CJ-Detonation calculations. A narrow high temperature region within the range was identified as showing homogenous (strong) ignition which showed generally good agreement with model predictions. Model comparisons with mild ignition cases should not be used to further refine kinetic mechanisms, though at these conditions, insight was gained into various ignition behavior. To the best of our knowledge, we present first shock tube data during ignition of high fuel loading CH4/O2 mixtures diluted with CO2 and N2.
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Barak, Samuel, Owen Pryor, Joseph Lopez, Erik Ninnemann, Subith Vasu, and Batikan Koroglu. "High-Speed Imaging and Measurements of Ignition Delay Times in Oxy-Syngas Mixtures With High CO2 Dilution in a Shock Tube." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63316.
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In this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% – 85% by volume. A 10% fuel concentration was consistently used throughout the experiments. This study looked at the effects of changing the equivalence ratios (ϕ), between 0.33, 0.5, and 1.0 as well as changing the fuel ratio (θ), hydrogen to carbon monoxide, from 0.25, 1.0 and 4.0. The study was performed at 1.61–1.77 atm and a temperature range of 1006–1162K. The high-speed imaging was performed through a quartz end wall with a Phantom V710 camera operated at 67,065 frames per second. From the experiments, when increasing the equivalence ratio, it resulted in a longer ignition delay time. In addition, when increasing the fuel ratio, a lower ignition delay time was observed. These trends are generally expected with this combustion reaction system. The high-speed imaging showed non-homogeneous combustion in the system, however, most of the light emissions were outside the visible light range where the camera is designed for. The results were compared to predictions of two combustion chemical kinetic mechanisms: GRI v3.0 and AramcoMech v2.0 mechanisms. In general, both mechanisms did not accurately predict the experimental data. The results showed that current models are inaccurate in predicting CO2 diluted environments for syngas combustion.
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Kuznetsov, M., A. Lelyakin, W. Breitung, J. Grune, K. Sempert, and A. Friedrich. "Dynamic Effects Under Gaseous Detonation and Mechanical Response of Piping Structures." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11643.
Full textAbstract:
A series of experiments and numerical simulations on hydrogen detonations in piping geometry was performed in order to reproduce the worst case scenario regarding the maximum internal pressure load and integrity of a piping structure to detonation pressure loads. To reproduce different scenarios of the detonation process and different pressure loads on the piping structure, nitrogen-diluted hydrogen-oxygen mixtures were studied. The mechanical response of 12.5-m long austenitic steel pipe with an outer diameter of 510 mm and wall thickness of 15 mm was investigated as well. A novel 1-D CFD code with a prescribed flame velocity model was used for the numerical simulation of the deflagration to detonation transition (DDT) and for the calculation of pressure loads at various positions along the tube. Different gas dynamic effects such as precursor shock waves and shock reflections on the maximum pressure were investigated in the calculations. Maximum pressure load of a pipe with two end flanges can be achieved near the DDT point and at the tube ends. Dilution of the hydrogen-oxygen mixture with nitrogen leads to a reduction of the mixture reactivity and to an increase of the run-up distance to the DDT point. In this case so called “late detonation initiation”, a cumulative effect of precursor shock wave, detonation ignition and shock wave reflections, can occur near the tube end. It produces extremely high pressure loads which can be 10 times higher than the CJ-detonation pressure of the initial gas mixture. Such scenarios of the combustion process have been experimentally reproduced with detailed pressure and strain measurements along the test tube.
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Kuznetsov, M., A. Lelyakin, and W. Breitung. "Numerical Simulation of Radiolysis Gas Detonation in BWR Exhaust Pipes and Mechanical Response of the Piping to the Detonation Pressure Loads." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48498.
Full textAbstract:
1-D numerical calculations of radiolysis gas detonation and mechanical response of a 12.5-m long BWR exhaust pipe have been performed. To reproduce one of scenarios of steam condensation with following radiolysis gas accumulation in an exhaust pipe initially filled with nitrogen at an initial pressure of 1.6 bar and temperature of 35°C, nitrogen diluted radiolysis gas mixtures were used for the numerical simulations. Nitrogen concentration in radiolysis gas composition was changed in the range of 0–80 mol.%. It permits to significantly change detonation properties of the test mixtures. Different gas dynamic effects such as a precursor shock wave and shock reflection on the maximum detonation pressure have shown in our calculations. Maximum pressure load of the piping can be achieved near the deflagration-to-detonation transition (DDT) point and at the tube end. At those positions the maximum pressure could be at least 2–2.5 times higher than the CJ detonation pressure. Dilution of the radiolysis gas mixture with nitrogen leads to reduction of the radiolysis gas detonability and to increase of run up distance to the DDT point. In this case so called “late detonation initiation” in a pre-compressed zone close to the reflection end can occur. It produces extremely high pressure load which can locally be 10 times higher than CJ-detonation pressure for steady state detonation. Mechanical response of the 12.5-m long austenitic steel pipe (Werkstoff Nr. 1.4541) with a diameter 510 mm and wall thickness of 15 mm was calculated for different detonation pressure loads. Maximum deformations of the pipe were obtained close to the DDT point and at the reflection end. It was shown that even for the worst case mixture with a “late detonation initiation” the deformation of tested pipe is very low (not more than 0.2%) and no danger exists for the integrity of the exhaust pipe under radiolysis gas detonation load. This 1D numerical code permits for the first time a continuously mechanistic analysis of the complicated processes with DDT and detonation propagation in closed pipes and it can be used for designers and for piping safety analysis.
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Maurya, Dalton, G. N. Jayaprakash, and C. Badarinath. "Challenges in Aero Gas Turbine Combustor Development." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59429.
Full textAbstract:
The Hot End Technologies Directorate (HETD) of Gas Turbine Research Establishment (GTRE) has the mandate to design, development and delivery of airworthy combustor and afterburner modules for a military aero gas turbine engine. In order to meet the mandate, the directorate takes the overall responsibility of design to manufacture of the combustion systems. This paper addresses the challenges faced in the development of combustor module. A short annular combustor with air blast atomizer is incorporated in the engine and it is a very important equipment of a gas turbine engine, wherein the heat energy is added to get Turbine Inlet Temperature (TET). It comprises of a pre-diffuser, a dump diffuser, outer annulus, inner annulus and a flame tube. There has been a basic liner, which was used in earlier engines and there was a shortfall in terms of performance parameters — allowable profile and pattern factors. To improve the performance, in collaboration with the M/s Central Institute of Aviation Motors (CIAM), Moscow, Russia, the liner was redesigned [1]. The secondary holes were totally blocked, primary and dilution holes were altered and it was incorporated with a new dome with a modified curvature. A new air blast atomizer with a swirler having an outer and inner pintle was incorporated. The basic liner was incorporated with these modifications and making this dome out of the high temperature resistance nickel chromium alloy was challenging and it was realized. The liner assemblies incorporating all the welding details have been realized within the GTRE. The combustor system was tested for ground light up to 4.3 km. The light up time was of the order of 5 s. The pressure loss was of the order of 4.9% at a combustor inlet Mn of 0.30. The circumferential and radial pattern factor for the modified liner is of 0.36 and 0.14 respectively.