Academic literature on the topic 'Ph.D Level'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Ph.D Level.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Ph.D Level"
1
Mukhtar, Wan Maisarah, Siti Nadiah Latib, Razman Mohd Halim, and Affa Rozana Abdul Rashid. "Graphene Based Macrobend Unclad SMF for Monitoring pH Level in Aqueous Environment." Solid State Phenomena 307 (July 2020): 78–83. http://dx.doi.org/10.4028/www.scientific.net/ssp.307.78.
Full textAbstract:
Partial unclad fibers with diameters ranging from d=121μm to d=125μm were fabricated using standard telecommunications optical fiber (SMF28) via low cost mechanical swipe-off technique. Graphene oxide (GO) was deposited using drop casting method on the outer side of the partial unclad SMF. IR laser with excitation wavelengths of λ=1310nm and λ=1550nm were launched along the graphene-coated SMF. The sensitivity of graphene based macrobend unclad SMFs were investigated by introducing two different pH of aqueous environment with values of 3.5 (acidic) and 12.5 (alkaline) that acted as sensing media. The optimum power loss was obtained as smallest diameter of partial unclad SMF with d=121μm was appointed. As uncoated SMF was replaced with the GO coated SMF which had been immersed into 3.5pH liquid solution, it was found that the optical power losses were increased about 6.79dBm and 5.15dBm using laser with λ1=1310nm and λ2=1550nm respectively. The uncoated SMFs experienced the increment of power losses about 2.11dBm and 5.15dBm as they were soaked into the solution with pH=12.5 using similar laser of λ1 and λ2. It is noteworthy to highlight the significant of graphene’s employment on macrobend unclad SMF by using λ1=1310nm in which better sensitivity and selectivity represented by maximum changes of power losses were apparently observed for both solutions. The usage of λ=1550nm exhibited poor selectivity where the partial unclad SMF unable to differentiate two contrasting pH solution. In conclusion, graphene based macrobend fiber optic sensor for pH detection was successfully developed by employing partial unclad SMF with cladding diameter of d=121μm and laser wavelength of λ=1310nm due to the enhancement of evanescent field’s strength.
2
Sulendre, Marsetyo, Takdir, Harper, and Poppi. "High Level of Energy and Protein Supplementation Effect on Feed Intake and Liveweight Gain of Bali Bulls Fed Elephant Grass." Proceedings 36, no. 1 (February 12, 2020): 91. http://dx.doi.org/10.3390/proceedings2019036091.
Full textAbstract:
This research was carried out on-farm at Malonas village, Central Sulawesi, Indonesia to examine the effect of high level supplementation of by-products formulated for high ME and CP. Feed intake, faecal pH and liveweight gain of Bali bulls was observed. The basal diet was elephant grass, and supplements were rice bran (RB), cassava (C), palm kernel meal (PKM), gliricidia (G) and urea. Fifty Bali bulls (weight 168±4.48 kg) were housed in individual pens for 18 weeks (2 introductory and 16 experimental) and allocated into five treatments: A= elephant grass (EG) ad libitum, B= EG offered at 1%W/d, plus 2.5%W/d mixed RB:G, (1:1), C = EG offered at 1%W/d plus 2.5%W/d mixed RB:PKM(1:1), D = EG offered at 1%W/d plus 2.5%W/d mixed C:G (1:1), E = EG offered at 1%W/d plus 2.5%W/d mixed C+ urea: PKM (1:1). Faecal pH was measured at weeks 3, 9 and 15. Bali bulls fed B, C, D and E, consumed supplement at the rate of 2.15, 2.19, 2.09 and 2.29 %W/d, respectively. Total feed intake was 2.47, 2.98, 2.99, 2.93, 3.13%W/d, liveweight gain was 0.30, 0.57, 0.60, 0.66, 0.69 g/d and faecal pH was 6.93, 6.76, 6.65, 6.45, 6.33 for treatment A, B, C, D, and E, respectively. Supplementation increased significantly (P<0.05) total feed intake, liveweight gain, but reduced faecal pH. The highest total feed intake and liveweight gain was achieved by treatment E. It is concluded that cassava can be provided at 1.15%W/d in combination with protein supplement for high liveweight gain of Bali bulls.
3
Wang, Rui, Fei Liu, and Li Hong Qin. "Influence of pH and Nitrate on Perchlorate Biological Reduction." Advanced Materials Research 356-360 (October 2011): 303–8. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.303.
Full textAbstract:
The pH and nitrate effect on the anaerobic biological reduction of perchlorate using acetate as carbon source was studied. Perchlorate reduction occurred throughout the pH range from 6.0 to 9.0. However, initiation of perchlorate reduction was rapid under neutral pH conditions. At initial pH 7, perchlorate reduction followed pseudo-first-order with the reaction rate constants was 0.3732 d-1 and the half-life time was 1.85 d. In the absence and presence of nitrate, the kinetics of perchlorate reduction with the reaction rate constants were 0.3229 d-1 and 0.2307 d-1 (after a lag phase for 3 d), the half-life time were 2.1 d and 6 d. With multiple additions of nitrate, perchlorate removal was observed with a longer lag period, the consequent production of high level nitrite may delay perchlorate degradation.
4
BUCHANAN, R. L., M. H. GOLDEN, and R. C. WHITING. "Differentiation of the Effects of pH and Lactic or Acetic Acid Concentration on the Kinetics of Listeria Monocytogenes Inactivation." Journal of Food Protection 56, no. 6 (June 1, 1993): 474–78. http://dx.doi.org/10.4315/0362-028x-56.6.474.
Full textAbstract:
The effects of pH and lactic acid or acetic acid concentration on Listeria monocytogenes inactivation were studied in brain heart infusion broth using a three strain mixture. Combinations of lactic acid/sodium lactate and acetic acid/sodium acetate were used to achieve concentrations of 0.1, 0.5, 1.0, and 2,0 M in conjunction with pH values of 4.0, 5.0, 6.0, and 7.0. Cultures adjusted with HCl to pH 3.0 to 7.0 in 0.5 pH unit intervals were used as 0.0 M controls. Each pH/concentration combination was inoculated to a level of 108 CFU/ml and incubated at 28°C for up to 60 d. Bacterial populations were determined periodically by plate counts. Inactivation was exponential after an initial lag period. Survivor curves (log# versus time) were fitted using a linear model that incorporated a lag period. The model was subsequently used to calculate D values and “time to a 4-D (99.99%) inactivation” (t4-D); t4-D values were directly related to pH and inversely related to acid concentration. At acid/pH combinations that supported growth, the level of the organism increased slightly (2- to 10-fold) before declining. In the HCl-adjusted controls with pH's ≤5.5, the rate of inactivation was linearly related to pH. In the presence of the monocarboxylic acids, the duration of the lag period and the rate of inactivation were dependent on the pH, as well as the identity and concentration of acid. 4-D inactivation times were related to the level of undissociated lactic and acetic acids. That relationship was described by the equations, t4-D = exp (−0.1773*LA0.5 + 7.3482) and t4-D = exp (−0.1468*AA0.5 + 7.3905) for lactic and acetic acids, respectively, where LA and AA are mM of undissociated acid. These relationships were used in conjunction with the Henderson-Hasselback equation to develop a model for predicting the rate of inactivation as a function of pH and total organic acid concentration.
5
Antanaitis, Ramūnas, Vida Juozaitienė, Dovilė Malašauskienė, and Mindaugas Televičius. "Inline Reticulorumen pH as an Indicator of Cows Reproduction and Health Status." Sensors 20, no. 4 (February 14, 2020): 1022. http://dx.doi.org/10.3390/s20041022.
Full textAbstract:
Our study hypothesis is that the interline registered pH of the cow reticulum can be used as an indicator of health and reproductive status. The main objective of this study was to examine the relationship of pH, using the indicators of the automatic milking system (AMS), with some parameters of cow blood components. The following four main groups were used to classify cow health status: 15–30 d postpartum, 1–34 d after insemination, 35 d after insemination (not pregnant), and 35 d (pregnant). Using the reticulum pH assay, the animals were categorized as pH < 6.22 (5.3% of cows), pH 6.22–6.42 (42.1% of cows), pH 2.6–6.62 (21.1% of cows), and pH > 6.62 (10.5% of cows). Using milking robots, milk yield, fat protein, lactose level, somatic cell count, and electron conductivity were registered. Other parameters assessed included the temperature and pH of the contents of reticulorumens. Assessment of the aforementioned parameters was done using specific smaX-tec boluses. Blood gas parameters were assessed using a blood gas analyzer (EPOC (Siemens Healthcare GmbH, Erlangen, Germany). The study findings indicated that pregnant cows have a higher pH during insemination than that of non-pregnant ones. It was also noted that cows with a low fat/protein ratio, lactose level, and high SCC had low reticulorumen pH. They also had the lowest blood pH. It was also noted that, with the increase of reticulorumen pH, there was an increased level of blood potassium, a high hematocrit, and low sodium and carbon dioxide saturation.
6
Tamam, Evsen, and Ilser Turkyilmaz. "Effects of pH and Elevated Glucose Levels on the Electrochemical Behavior of Dental Implants." Journal of Oral Implantology 40, no. 2 (April 1, 2014): 153–59. http://dx.doi.org/10.1563/aaid-joi-d-11-00083.
Full textAbstract:
Implant failure is more likely to occur in persons with medically compromising systemic conditions, such as diabetes related to high blood glucose levels and inflammatory diseases related to pH levels lower than those in healthy people. The aim of this study was to investigate the effects of lower pH level and simulated- hyperglycemia on implant corrosion as these effects are critical to biocompatibility and osseointegration. The electrochemical corrosion properties of titanium implants were studied in four different solutions: Ringer's physiological solution at pH = 7.0 and pH = 5.5 and Ringer's physiological solution containing 15 mM dextrose at pH = 7 and pH = 5.5. Corrosion behaviors of dental implants were determined by cyclic polarization test and electrochemical impedance spectroscopy. Surface alterations were studied using a scanning electron microscope. All test electrolytes led to apparent differences in corrosion behavior of the implants. The implants under conditions of test exhibited statistically significant increases in Icorr from 0.2372 to 1.007 μAcm−2, corrosion rates from 1.904 to 8.085 mpy, and a decrease in polarization resistances from 304 to 74 Ω. Implants in dextrose-containing solutions were more prone to corrosion than those in Ringer's solutions alone. Increasing the acidity also yielded greater corrosion rates for the dextrose-containing solutions and the solutions without dextrose.
7
Furukawa, R., J. E. Wampler, and M. Fechheimer. "Measurement of the cytoplasmic pH of Dictyostelium discoideum using a low light level microspectrofluorometer." Journal of Cell Biology 107, no. 6 (December 1, 1988): 2541–49. http://dx.doi.org/10.1083/jcb.107.6.2541.
Full textAbstract:
Pyranine was employed as a sensitive pH indicator in a low light level microspectrofluorometer. The in vivo and in vitro standard curves of the 460/410-nm fluorescence excitation ratio of pyranine as a function of pH are identical. Therefore, pyranine is specifically sensitive to cytoplasmic pH in Dictyostelium. The cytoplasmic pH of single cells in a population of Dictyostelium discoideum amoebae was obtained for the first time. The median cytoplasmic pH of vegetative amoebae was 7.19. Carbonyl cyanide m-chlorophenylhydrazone, a mitochondrial uncoupler and a protonophore, lowered the median cytoplasmic pH to 6.12 when the extracellular pH was 6.1. This result is in accord with the protonophore activity of carbonyl cyanide m-chlorophenylhydrazone. Interest in the cytoplasmic pH of Dictyostelium has been greatly stimulated by the theory that cytoplasmic acidification promotes development of pre-stalk cells, while cytoplasmic alkalinization favors the pre-spore pathway (Gross, J. D., J. Bradbury, R. R. Kay, M. J. Peacey. 1983. Nature (Lond.). 303:244-245). The theory postulates that diethylstilbestrol (DES), an inducer of stalk cell differentiation and a plasma membrane proton translocating ATPase inhibitor, should cause acidification of the cytosol. Previous measurements of the effects of stalk cell inducers including DES on intracellular pH using 31P nuclear magnetic resonance measurements have failed to confirm the predictions of the theory, and have suggested that significant modification of the model may be required. Using pyranine as the pH indicator, we find that the median cytoplasmic pH in cells treated with 10 microM DES dropped from 7.19 to pH 6.02. This effect is consistent with the pharmacological action of DES and with the proposal that DES, a stalk cell inducer, should acidify the cytosol. These results provide direct support for the theory that cytoplasmic pH is an essential regulator of the developmental pathway in Dictyostelium.
8
Limbach, Joseph R., Estefania Pérez Calvo, and Hans H. Stein. "259 Effects of dietary crude protein level on growth performance, fecal score, gastrointestinal pH, and blood characteristics in weanling pigs fed antibiotic-free diets." Journal of Animal Science 98, Supplement_3 (November 2, 2020): 91–92. http://dx.doi.org/10.1093/jas/skaa054.159.
Full textAbstract:
Abstract Reducing dietary CP with crystalline AA supplementation has been proposed as a nutritional strategy to control post-weaning diarrhea in response to global concerns about negative effects of sub-therapeutic use of antibiotics. One hundred eighty weaned pigs (5.53 ± 0.88 kg) were randomly allotted to 3 treatments with 12 replicate pens per treatment for 28 d. Treatments included antibiotic-free, corn-soybean meal diets containing 22% and 19% CP, adequate in AA, and a 16% CP diet that provided AA below the requirement. Daily feed provisions and pig weights were recorded weekly. Fecal scores were assessed every other day. Blood samples were collected on d 1, 6, 13, 20, and 27 and 1 pig per pen was euthanized on d 12. Data for growth performance, fecal scores, and intestinal pH were analyzed by contrast statements and data for blood characteristics were analyzed using repeated measures. Results indicated that reducing dietary CP linearly (P ≤ 0.05) reduced overall ADG, G:F, body weight, and fecal scores of pigs. Reduction in dietary CP resulted in greater reduction in BUN after d 13 (treatment × day interaction, P ≤ 0.05). Total protein, albumin, and vitamin A and E in serum were lowest (P ≤ 0.05) on d 13, and pigs fed 16% CP had reduced (P ≤ 0.05) albumin compared with pigs fed other diets. The pH in the ileum was reduced (P ≤ 0.05) as dietary CP decreased but pH in the colon of pigs fed 19% CP was the lowest (P < 0.05) at d 13. In conclusion, reducing CP to 19% and 16% in antibiotic-free diets for weanling pigs reduces fecal score without impairing the growth performance during the first 14 d after weaning. However, additional strategies are needed to maintain growth performance during the next two weeks.
9
Rana, Neha, Brent A. Sellers, Jason A. Ferrell, Gregory E. MacDonald, Maria L. Silveira, and Joao M. Vendramini. "Impact of Soil pH on Bahiagrass Competition with Giant Smutgrass (Sporobolus indicusvar.pyramidalis) and Small Smutgrass (Sporobolus indicusvar.indicus)." Weed Science 61, no. 1 (March 2013): 109–16. http://dx.doi.org/10.1614/ws-d-12-00070.1.
Full textAbstract:
Smutgrass is an invasive, well-rooted perennial that has long been recognized as an aggressive weed throughout Florida and in the subtropical regions of the United States. Small smutgrass and giant smutgrass are the two predominant smutgrass varieties found in Florida. The native soil pH of Florida flatwoods is 4.5 to 5.0 which is lower than the level of soil pH recommended for optimum bahiagrass growth. Therefore, replacement series experiments were conducted in a greenhouse in 2010 and 2011 to compare the competitive ability of bahiagrass with each of the two varieties of smutgrass at three levels of soil pH (4.5, 5.5, and 6.5), two densities; 4 (low) and 8 (high) plants pot−1, and at five planting ratios of 100 : 0, 75 : 25, 50 : 50, 25 : 75, and 0 : 100. Relative competitive ability and aggressivity of giant smutgrass was greater than bahiagrass across all pH levels and densities, whereas relative competitive ability and aggressivity of bahiagrass was greater than small smutgrass in all pH levels and densities, except at pH 6.5. At pH 5.5, biomass accumulation of giant smutgrass was at least 73% higher than bahiagrass, whereas small smutgrass biomass was at least 46% lower than bahiagrass at equal planting ratios of both low and high densities. Differential responses were observed on bahiagrass competitive ability with small and giant smutgrass. Amending soil pH is not a likely option to increase the growth and competitive ability of bahiagrass over giant smutgrass. However, for small smutgrass, it is likely to increase the aggressivity of bahiagrass in bahiagrass–small smutgrass mixture, unless the soil pH is raised above 5.5.
10
Ohler, Tracy A., and Cary A. Mitchell. "734 PB 026 EFFECT OF CO2 LEVEL ON COWPEA CANOPY PHOTOSYNTHESIS AND GROWTH." HortScience 29, no. 5 (May 1994): 538b—538. http://dx.doi.org/10.21273/hortsci.29.5.538b.
Full textAbstract:
The vigorous growth habit and tolerances to heat, water, and acid stresses suggest cowpea as a candidate species for Controlled Ecological Life-Support Systems (CELSS). The low fat, high protein, moderate carbohydrate content of the edible leaves and seeds complement cereal grains in the vegetarian diets planned for CELSS. Cowpea canopy densities of 3.6, 7.2, 10.7, and 14.3 plants·m-2 were grown under CO2 levels of 400 or 1200 μl·l-1. Plants were grown in a deep-batch recirculating hydroponic system. pH was maintained at 5.5 by a pH controller with an in-line electrode. The nutrient solution was replaced as needed and sampled weekly for analysis by inductively coupled plasmaatomic emission spectrometry. Fluorescent lights provided 674±147 μmol·m-2s-1 PAR for an 8-hour photoperiod. Day/night temperature was maintained at 27/25°C. CO2 draw-down within the growth chamber was measured to calculate net photosynthesis. Power consumption was metered and canopy quantum efficiency was calculated. Crop yield rate (g·m-2·d-1). harvest index (% edible biomass), and yield efficiency (edible g·m-2·d-1·(nonedible g)-1) were determined to evaluate the productivity of cowpea for a CELSS. This study was supported by NASA Grant NAGW-2329.
Book chapters on the topic "Ph.D Level"
1
Schweitzer, George K., and Lester L. Pesterfield. "The V–Cr–Mn Group." In The Aqueous Chemistry of the Elements. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195393354.003.0016.
Full textAbstract:
The three elements to be treated in this chapter (V, Cr, Mn) are the third, fourth, and fifth members of the first transition series. The first two members (Sc, Ti) have been treated in previous chapters (Chapters 12 and 13). The ten elements of this first transition series (Sc through Zn) are characterized by electron activity in the 3d–4s levels. All elements in the 3d transition series are metals, and many of their compounds tend to be colored as a result of unpaired electrons. Most of the elements have a strong tendency to form complex ions due to participation of the d electrons in bonding. Since both the 4s and the 3d electrons are active, most of the elements show a considerable variety of oxidation states (Sc and Zn being exceptions). For the first five (Sc through Mn), the maximum oxidation number is the total number of electrons in the 4s and 3d levels. Complexing is often so strong that the most stable oxidation state for simple compounds may differ from that for complex compounds. a. E–pH diagram. The E–pH diagram in Figure 14.1 shows V in oxidation states of 0, II, III, IV, and V. This diagram, which involves vanadium at 10−3.0 M is somewhat oversimplified in that there are some isopolyanions present in the 4–6 pH regions. The prevalence of isopolyanions increases as the V concentration increases. This is illustrated in Figure 14.2 which has V at 10−1.0 M. Further, the cations V+2, V+3, VO+2, and VO2+ are probably aquated to satisfy a coordination number of six, and the V(OH)3 may actually be hydrated V2O3. Note that the soluble solution chemistries of V(IV) and V(V) are dominated by the VO+2 and VO2+ complex ions. Three of these cations (III, IV, V) are subject to hydrolysis, the processes setting in around pH values of just under 3, 3, and 2. The E–pH diagram indicates that elemental V is very active, but a thin coat of oxide protects it from all except strong action.
2
Schweitzer, George K., and Lester L. Pesterfield. "The Fe–Co–Ni Group." In The Aqueous Chemistry of the Elements. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195393354.003.0017.
Full textAbstract:
The three elements to be treated in this chapter (Fe, Co, Ni) are the sixth, seventh, and eighth members of the first transition series. The first five members (Sc, Ti, V, Cr, Mn) have been treated in previous chapters (Chapters 12, 13, and 14). The ten elements of this first transition series (Sc through Zn) are characterized by electron activity in the 4s–3d levels. All elements in the 3d transition series are metals, and many of their compounds tend to be colored as a result of unpaired electrons. Most of the elements have a strong tendency to form complex ions due to participation of the d electrons in bonding. Unlike the previous three elements (V, Cr, Mn), these three do not show a variety of oxidation states. The higher oxidation states are almost absent in compounds, Fe showing principally the II and III, Co the II and III, and Ni only the II. The III states are less stable than the II states unless they are stabilized by complex formation. The resemblance of these three elements is notable, they being more like each other than they are to the elements below them. a. E–pH diagram. The E–pH diagram in Figure 15.1 shows Fe in oxidation states of 0, II, and III. This diagram, which involves iron at 10−1.0 M is oversimplified in several ways. The Fe(II) and Fe(III) cations are more properly designated as Fe(HOH)6+2 and Fe(HOH)6+3, reflecting the coordination number of 6. The region just to the left of the Fe+2/Fe(OH)2 line involves Fe(OH)+, and the region just to the left of the Fe+3/FeO(OH) line involves numerous hydroxo complexes such as Fe(HOH)5OH+2 and Fe(HOH)4(OH)2+. At very high pH values, there is a tendency for Fe(OH)2 to be converted to HFeO2−, and at very high E values, the powerful oxidant, red-purple FeO4−2 can be produced. When these latter five species are introduced, Figure 15.2 results. This, too, is probably simplified since it is known that other species are present, such as Fe2(OH)4+4 and Fe3(OH)4+5. The species FeO4−2 can only be prepared in a very strong base.
Conference papers on the topic "Ph.D Level"
1
Martin, Andrew J., Shigeki Kuroda, Keiji Morimoto, Gento Kamei, and Masao Shiotsuki. "Key Issues Identified From Project TRU-2 on the Generic Co-Location Concept of Transuranic (TRU) Waste and High-Level Radioactive Waste (HLW) Repositories in Japan." In The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7231.
Full textAbstract:
The Federation of the Electric Power Companies of Japan (FEPC) and the Japan Atomic Energy Agency (JAEA) have been collaborating with relevant organisations to promote the safe geological disposal of transuranic (TRU) waste following the already established disposal policy for high-level radioactive waste (HLW) in Japan. A result of this intensive collaborative effort was the production of a recent progress report (TRU-2) which describes the generic R&D for TRU-waste disposal in Japan. In order to improve feasibility and reduce costs and the burden on siting, the concept of co-locating TRU-waste and HLW repositories in a single complex was assessed in detail and compared with the results from several other countries that have also looked at co-location disposal. Heat from HLW, high pH plume(s) from the large amounts of cementitious materials used in the engineered barrier system (EBS) of TRU waste, and nitrates and organic materials in certain types of TRU waste were identified as critical reciprocal influences that might degrade the performance of the TRU/HLW co-location disposal system over the long-term. It was shown that these reciprocal influences could be avoided by establishing a separation distance between the two repositories of approximately 300 meters.
2
Yu, Weiwei, Pedro M. Vargas, and Jonathan Bowman. "Consistent Endurance Fatigue Knockdown Factors for Sour Service From Industry-Wide Database." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50204.
Full textAbstract:
The embrittlement of steel in the presence of water and hydrogen sulfide is a well known phenomenon. For the resulting degradation in fatigue performance, the industry today applies a knock-down factor onto in-air S-N endurance curve that relates the sour-service life to the in-air performance. Several published results are available, and most of these, although rigorous in test approach, report knock-down factors that include unspecified levels of conservatism, consistent with that particular author’s engineering intuition. (For example, typically a lower bound S-N curve in sour-service testing is related to a mean S-N curve in-air). This paper summarizes all of the published small scale sour service testing results, and applies a consistent knock-down factor calculation. Analyses of the data show that sour degradation is highly correlated to H2S concentration and solution pH value. In practice frequency scanning test is highly recommended since sour fatigue test results are highly dependent on loading frequency. Although the database is small, some trends are discernable. In particular, observations indicate that sour service exposure may act as an equalizer, removing the initiation life associated with the time for initial micro-defects at the weld toes to become macro-cracks and leaving only aggravated propagation due to sour service. In this paper, we use initiation life (for welds) to describe the life for the micro-defects (∼0.1mm height) to become macro-cracks (∼1.0 mm height), and a postulation is made that associates the fatigue performance of girth welds (F2, E, D, etc.) with the size and magnitude presence of these micro-defects. The metal surface attack of the sour environment is postulated to provide pitting-like initiation sites for the macro-crack for fatigue propagation. As a base we can use the F2 level performance as the performance due to presence of macro-cracks, and any margin for the D and E level fatigue performances then is associated with more benign initial micro-defects. Once we remove the differences in initiation life; all of the sour performance converges on a single lower performance curve. In this scenario, the knockdown factor is more consistently computed from a standard performance S-N curve rather than the same girth weld’s in-air performance since the in-air data may include significant initiation life. Furthermore, if project sour condition is less severe than NACE TM0177, Solution B with pH = 3.5 and H2S partial pressure = 70mbar, a knock down factor of 45 indexed to BS7608 E design curve is supported from the current database. This provides a design recommendation which can be used for preliminary design in sour environments.
3
Cummings, Richard, Andrew J. Baker, Trevor Sumerling, John Shevelan, and Amy Huntington. "The LLWR’s 2011 Environmental Safety Case." In ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2011. http://dx.doi.org/10.1115/icem2011-59135.
Full textAbstract:
The UK’s Low Level Waste Repository Ltd submitted an Environmental Safety Case (ESC) for the disposal of low-level waste to the Environment Agency on the 1st of May 2011. The ESC is a major submission that will decide the future use of the Repository and has major implications for the success of the UK’s LLW Strategy and decommissioning programme. This paper provides an overview of the work that has been carried out to support the submission. Key aspects of this ESC include: • detailed investigations of existing disposals, based on careful examination of existing records and other investigations, including interviews with former operational staff; • analysis of uncertainties in future disposals; • modelling of the biogeochemical evolution of the disposal system, which provides understanding of the evolution of pH, Eh and gas generation and thence underpinning for radionuclide releases in groundwater and gas; • development of a 3-D groundwater flow model, calibrated against observed heads and with a detailed representation of the engineered features; • analysis of coastal erosion and its impacts; • a major focus on optimisation based on detailed technical studies; • a conclusion that existing disposals do not require remediation; • the choice of a concrete vault design with permeable side walls designed to avoid bathtubbing after the end of management control; • a comprehensive set of assessment calculations, including thorough analysis of uncertainties, which demonstrate consistency with the Environment Agency’s risk and dose guidance levels; • revision of the LLWR’s WAC, based in part on the use of the ‘sum of fractions’ approach; • the use of a safety case document structure that emphasises key safety arguments in a Level 1 document and provides supporting evidence in a series of Level 2 documents; • the provision of a Level 2 document that describes in detail how each aspect of the regulatory guidance has been addressed. In the future, the 2011 ESC will be maintained using a formal system of change control. It will be used as a tool for decision making concerning the future development of the LLWR and waste acceptance.
4
Sloan, Gregory, Zhi-Gang Feng, Kiran Bhaganagar, and Debyjoti Banerjee. "Coupled Direct Numerical Simulation and Experimental Approach to Develop Framework for Nano Fluids." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89271.
Full textAbstract:
Nanofluids are considered to be attractive as heat transfer fluids (HTF) and thermal energy storage (TES) for concentrated solar power (CSP) applications. Solvents doped with relatively low concentrations of nanoparticles (with diameters up to 100 nm) are termed as nanofluids. Numerical models for exploring the forces experienced by the nanoparticles are needed in order to ascertain the transport processes responsible for the anomalous material properties of the nanofluids that are observed in experimental measurements. In this study a multiscale approach to modeling the forces acting on these particles was performed and the dynamics of transient nanoparticle agglomeration have been explored. The validity of the multiscale approach is demonstrated by examining a pair of nanoparticles in a fluid. The force interactions due to the presence of the electric double layer (EDL) were identified as a significant factor in determining the propensity for agglomerative of the nanoparticles. Simulations were performed to demonstrate the clustering and agglomeration of an ensemble of nanoparticles. The simulation results provide an estimate for the time scale for the agglomeration and the resultant structure of the agglomerated ensemble of nanoparticles. Subsequently simulations were performed using this numerical model corresponding to the available experimental data in the literature. The predictions from the numerical simulations show that the change in zeta potential (determined in part by the pH of the solvent phase) is a crucial parameter that affects the level of agglomeration of the nanoparticles. Finally, the numerical scheme is extended for performing true 3-D simulation. This approach is more sophisticated than the contemporary schemes that are reported in the literature that project 3-D forces on to a 2-D plane.
5
Johnston, Dennis C., and Thomas G. Hrncir. "Using In-Line Inspection to Address Deformations Containing Near-Neutral pH Stress Corrosion Cracking." In 2002 4th International Pipeline Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ipc2002-27063.
Full textAbstract:
Marathon Ashland Pipe Line LLC (MAPL) experienced a pipeline release on January 27, 2000 from cracking in a bottom-side shallow deformation. The crack that caused the release was determined to have propagated due to corrosion fatigue that progressed from an area of near-neutral pH stress corrosion cracks. A combination of a transverse field magnetic flux inspection (TFI) tool and a slope-deformation tool were used to inspect the entire pipeline segment for additional injurious deformations that could contain cracks. The TFI tool data were used to differentiate deformations that contained linear indications (typically cracks or corrosion) from deformations that did not. The slope-deformation tool data were used to measure the deformation magnitudes and shapes and to assist with locating the (TFI) deformations that were to be excavated. The pipe conditions necessary for these types of cracking to occur are discussed as well as the findings of the in-line inspection and remediation program. Prior to this release, it was perceived within the industry that constrained shallow deformations were not likely to fail catastrophically. The failure mechanism, particularly from constrained deformations, was normally as a leak. The near-neutral pH stress corrosion cracking phenomenon within deformations was first thought to be a unique event. Based on the investigation program conducted by MAPL, this phenomenon was identified elsewhere within the pipeline system. Based on MAPL’s investigation, pipelines susceptible to or containing slight deformations (typically high D/t ratios) in areas with groundwater containing high levels of dissolved carbon dioxide and coated with materials prone to shielding cathodic protection may be particularly susceptible to the deformation near-neutral pH stress corrosion cracking phenomenon.
6
Orthner, Carolyn L., Prabir Bhattacharya, and Dudley K. Strikland. "PURIFICATION AND CHARACTERIZATION OF A PROTEIN C ACTIVATOR FROM THE VENOM OF AGKISTRODON CONTORTRIX CONTORTRIX." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643813.
Full textAbstract:
There are two recent reports on the purification and properties of a protein C activator (PCA) from the venom of the Southern copperhead snalce. The purification of a 37,000 Mr nonenzymatic PCA (Martinoli and Stocker, Thrcmb. Res. 43, 253, 1976) as well as of a 20,000 Mr thrombin-like enzyme (Klein and Walker, Biochem. ,25, 4175, 1986) have been described. The purpose of this investigation was to purify and further characterize the PCA(s) from this vencm. A PCA has been isolated by sulphopropyl-Sephadex followed by gel filtration chromatography resulting in approximately a 100-fold purification with a 50% yield. PCA appeared as a single band on SDS-PAGE with an estimated Mr of 32,000 or 37,000 in the absence or presence of β-mercaptoethanol, respectively. High pressure gel permeation cinematography of PCA in Tris-buffered saline, pH 7.5 resulted in a single protein peak with a Mr of 39,000 which was coincident with activity. PCA was a potent activator of human protein C (PC) with a Km for PC of 0.6uM and a Vm of 0.02 sec-1. In addition, PCA catalyzed the arnidolysis of Tosyl-gly-pro-arg-p-nitroanilide (TGPRpNA) with a Km of 1.1 irM and a Vim of 66 sec-1. The rate of arnidolysis of five other pept idyl-arginyl-pNA substrates each tested at 1.0 mM was < 10% that of TGPRpNA. PCA was inhibited by nitrophenylguanidi-nobenzoate (NPGB), phenylmethylsulphonylflouride, D-phe-pro-arg-chloromethyi_ketone (PPACK) and soybean trypsin inhibitor indicating that PCA is a serine protease. The active site concentration of PCA as measured by NPGB titration was 90% that of the protein concentration. Measurement of the rate of PCA inhibition at varying levels of PPACK indicated that it had a Ki of 34uM .and an aUcylation rate constant of 0.09 min-1. PCA activation of PC was completely inhibited by CaC12 with an apparent Ki of 99uM. Since neither PCA arnidolysis of TGPRpNA nor inhibition by PPACK was affected by Ca2+, the effect of this metal was likely on the substrate PC. In summary, a PCA has been purified to homogeneity and has properties which are distinct from those reported. PCA premises to be a useful enzyme in studies of PC and its activation.