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1
Saravanan, S. "Stacking of InAs QDs with Different Spacer Layer Thickness on GaAs Substrate by Molecular Beam Epitaxy." Advanced Science Letters 24, no. 8 (August 1, 2018): 5574–77. http://dx.doi.org/10.1166/asl.2018.12152.
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InAs QDs were grown by supplying 2.5 mono-layers (MLs) of InAs at 500 °C in a molecular beam epitaxial (MBE) system. The QDs are approximately 4–6 nm height with an areal density of 3×85 ×1010 cm−2 for single layer QDs. Typical diameter was found to be about 15–25 nm. InAs QDs were stacked with the spacer layer thickness of 5, 10, 15, 25 and 35 nm. For 15 nm of spacer layer thickness the QDs density decreased to 2.62×1010 cm−2 and again increased for 35 nm spacer layer and reached to the value of 3.65×1010 cm−2. The 14 K photoluminescence (PL) spectra of single layer InAs QDs covered by GaAs layer centered at 1079 nm. For the stacking of InAs QDs with spacer layer thickness of 5 and 10 nm another peak appeared around 1100 nm due to size broadening of QDs because of strain propagation to next layer due to less thickness of spacer layer. When the thickness of the spacer layer increased to 35 nm the peak position is around 1073 nm and the intensity increased more than 3 fold when compare to single layer QDs.
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ZUO, XUE, HUA ZHU, YUANKAI ZHOU, CONG DING, and GUODONG SUN. "DEVELOPMENT OF FRACTAL DIMENSION AND CHARACTERISTIC ROUGHNESS MODELS FOR TURNED SURFACE OF CARBON STEELS." Fractals 24, no. 04 (December 2016): 1650042. http://dx.doi.org/10.1142/s0218348x16500420.
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Relationships between material hardness, turning parameters (spindle speed and feed rate) and surface parameters (surface roughness [Formula: see text]a, fractal dimension [Formula: see text] and characteristic roughness [Formula: see text] are studied and modeled using response surface methodology (RSM). The experiments are carried out on a CNC lathe for six carbon steel material AISI 1010, AISI 1020, AISI 1030, AISI 1045, AISI 1050 and AISI 1060. The profile of turned surface and the surface roughness value are measured by a JB-5C profilometer. Based on the profile data, [Formula: see text] and [Formula: see text] are computed through the root-mean-square method. The analysis of variance (ANOVA) reveals that spindle speed is the most significant factors affecting [Formula: see text]a, while material hardness is the most dominant parameter affecting [Formula: see text]. Material hardness and spindle speed have the same influence on [Formula: see text]. Feed rate has less effect on three surface parameters than spindle speed and material hardness. The second-order models of RSM are established for estimating [Formula: see text]a, [Formula: see text] and [Formula: see text]. The validity of the developed models is approximately 80%. The response surfaces show that a surface with small [Formula: see text]a and large [Formula: see text] and [Formula: see text] can be obtained by selecting a high speed and a large hardness material. According to the established models, [Formula: see text]a, [Formula: see text] and [Formula: see text] of six carbon steels surfaces can be predicted under cutting conditions studied in this paper. The results have an instructive meaning to estimate the surface quality before turning.
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Evans, A. S., D. T. Frayer, Vassilis Charmandaris, Lee Armus, Hanae Inami, Jason Surace, Sean Linden, et al. "GOALS-JWST: Hidden Star Formation and Extended PAH Emission in the Luminous Infrared Galaxy VV 114." Astrophysical Journal Letters 940, no. 1 (November 1, 2022): L8. http://dx.doi.org/10.3847/2041-8213/ac9971.
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Abstract James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) images of the luminous infrared (IR) galaxy VV 114 are presented. This redshift ∼0.020 merger has a western component (VV 114W) rich in optical star clusters and an eastern component (VV 114E) hosting a luminous mid-IR nucleus hidden at UV and optical wavelengths by dust lanes. With MIRI, the VV 114E nucleus resolves primarily into bright NE and SW cores separated by 630 pc. This nucleus comprises 45% of the 15 μm light of VV 114, with the NE and SW cores having IR luminosities, L IR(8 − 1000 μm) ∼ 8 ± 0.8 × 1010 L ⊙ and ∼ 5 ± 0.5 × 1010 L ⊙, respectively, and IR densities, ΣIR ≳ 2 ± 0.2 × 1013 L ⊙ kpc−2 and ≳ 7 ± 0.7 × 1012 L ⊙ kpc−2, respectively—in the range of ΣIR for the Orion star-forming core and the nuclei of Arp 220. The NE core, previously speculated to have an active galactic nucleus (AGN), has starburst-like mid-IR colors. In contrast, the VV 114E SW core has AGN-like colors. Approximately 40 star-forming knots with L IR ∼ 0.02–5 × 1010 L ⊙ are identified, 28% of which have no optical counterpart. Finally, diffuse emission accounts for 40%–60% of the mid-IR emission. Mostly notably, filamentary polycyclic aromatic hydrocarbon (PAH) emission stochastically excited by UV and optical photons accounts for half of the 7.7 μm light of VV 114. This study illustrates the ability of JWST to detect obscured compact activity and distributed PAH emission in the most extreme starburst galaxies in the local universe.
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Miyashita, Takuto, Takeshi Kondo, Kohei Ikeda, Kazumichi Yoshii, Feng-Lei Hong, and Tomoyuki Horikiri. "Offset-locking-based frequency stabilization of external cavity diode lasers for long-distance quantum communication." Japanese Journal of Applied Physics 60, no. 12 (November 10, 2021): 122001. http://dx.doi.org/10.35848/1347-4065/ac2e67.
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Abstract Quantum repeaters are required for long-distance quantum communication. For efficient coupling of quantum entangled photon sources with narrow-linewidth quantum memories, we performed the frequency stabilization of two lasers at 1514 and 1010 nm. The 1514 nm pump laser of the entangled photon source exhibited a frequency stability of 3.6 × 10–12 (τ = 1 s). The 1010 nm pump laser of the wavelength conversion system exhibited a frequency stability of 3.4 × 10–12 (τ = 1 s). The stabilities of both lasers were approximately two orders of magnitude smaller than the frequency width of 4 MHz of the Pr:YSO quantum memory. Such frequency-stabilized lasers can realize the remote coupling of a quantum memory and an entangled photon source in quantum repeaters.
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Robinson, K. G., H. M. Dionisi, G. Harms, A. C. Layton, I. R. Gregory, and G. S. Sayler. "Molecular assessment of ammonia- and nitrite-oxidizing bacteria in full-scale activated sludge wastewater treatment plants." Water Science and Technology 48, no. 8 (November 1, 2003): 119–26. http://dx.doi.org/10.2166/wst.2003.0460.
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Nitrification was assessed in two full-scale wastewater treatment plants (WWTPs) over time using molecular methods. Both WWTPs employed a complete-mix suspended growth, aerobic activated sludge process (with biomass recycle) for combined carbon and nitrogen treatment. However, one facility treated primarily municipal wastewater while the other only industrial wastewater. Real time PCR assays were developed to determine copy numbers for total 16S rDNA (a measure of biomass content), the amoA gene (a measure of ammonia-oxidizers), and the Nitrospira 16S rDNA gene (a measure of nitrite-oxidizers) in mixed liquor samples. In both the municipal and industrial WWTP samples, total 16S rDNA values were approximately 2-9 × 1013 copies/L and Nitrospira 16S rDNA values were 2-4 × 1010 copies/L. amoA gene concentrations averaged 1.73 × 109 copies/L (municipal) and 1.06 × 1010 copies/L (industrial), however, assays for two distinct ammonia oxidizing bacteria were required.
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MICHALSKI, C. B., R. E. BRACKETT, Y. C. HUNG, and G. O. I. EZEIKE. "Use of Capillary Tubes and Plate Heat Exchanger to Validate U.S. Department of Agriculture Pasteurization Protocols for Elimination of Salmonella Enteritidis from Liquid Egg Products." Journal of Food Protection 62, no. 2 (February 1, 1999): 112–17. http://dx.doi.org/10.4315/0362-028x-62.2.112.
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D values for a five-strain cocktail of Salmonella Enteritidis in five different liquid egg products (whole egg, egg yolk, egg white, egg yolk + 5% sucrose + 5% NaCl, and egg yolk + 10% NaCl) were determined using 100-μl capillary tubes. The egg products were inoculated with approximately 1 × 1010 organisms/ml and heated in capillary tubes to temperatures ranging from 51 to 68°C for various time intervals. Using a pilot scale plate heat exchanger, the U.S. Department of Agriculture (USDA) protocols for pasteurization were also evaluated using egg products inoculated with approximately 1 × 107 Salmonella Enteritidis/ml. Results of experiments with capillary tubes suggested that almost all processes would result in less than the 9D process recommended by the USDA. However, when the egg products were pasteurized using the plate heat exchanger, a greater than 9D process was achieved for Salmonella Enteritidis in all products except egg yolk containing 5% sucrose + 5% NaCl, which received approximately a 4D process.
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Li, Shulong, and Zhizhang Wang. "Time, Spatial and Component Characteristics of Agricultural Carbon Emissions of China." Agriculture 13, no. 1 (January 14, 2023): 214. http://dx.doi.org/10.3390/agriculture13010214.
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In this study, the time trend, regional distribution and component characteristics of the agricultural carbon emissions (ACEs) of China are analyzed. The estimation methods of each component of the ACE are introduced. According to the annually provincial panel data set with the 31 provinces from 1996 to 2019, the time trend, regional distribution and component characteristics are empirically discussed. Meanwhile, since it is also worthwhile to explore the effect of the ACE on economic growth, econometric models such as the pooled ordinary least squares (OLS) and fixed effect (FE) models are employed to examine the inverted “U”-shape effect of ACE on both of the agricultural GDP and GDP under the control of other variables. The results show that (1) the carbon emission started to fall after 2015; (2) the majority source of the agricultural carbon emission is caused by chemical fertilizer, which is approximately half of the total; (3) the current provincial ACE levels (0.287 ×1010 kg in 2019) are significantly smaller than the estimated optimal level for agricultural GDP as well as GDP (respectively, 1.003×1010 kg and 1.256×1010 kg). In light of this, environmental protection and agricultural development are currently conflicted. Therefore, we suggest that the government should accept a trade-off between economic growth and the quality of the environment.
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Cernicharo, J., C. Cabezas, M. Agúndez, B. Tercero, J. R. Pardo, N. Marcelino, J. D. Gallego, F. Tercero, J. A. López-Pérez, and P. de Vicente. "TMC-1, the starless core sulfur factory: Discovery of NCS, HCCS, H2CCS, H2CCCS, and C4S and detection of C5S." Astronomy & Astrophysics 648 (April 2021): L3. http://dx.doi.org/10.1051/0004-6361/202140642.
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We report the detection of the sulfur-bearing species NCS, HCCS, H2CCS, H2CCCS, and C4S for the first time in space. These molecules were found towards TMC-1 through the observation of several lines for each species. We also report the detection of C5S for the first time in a cold cloud through the observation of five lines in the 31–50 GHz range. The derived column densities are N(NCS) = (7.8 ± 0.6) × 1011 cm−2, N(HCCS) = (6.8 ± 0.6) × 1011 cm−2, N(H2CCS) = (7.8 ± 0.8) × 1011 cm−2, N(H2CCCS) = (3.7 ± 0.4) × 1011 cm−2, N(C4S) = (3.8 ± 0.4) × 1010 cm−2, and N(C5S) = (5.0 ± 1.0) × 1010 cm−2. The observed abundance ratio between C3S and C4S is 340, that is to say a factor of approximately one hundred larger than the corresponding value for CCS and C3S. The observational results are compared with a state-of-the-art chemical model, which is only partially successful in reproducing the observed abundances. These detections underline the need to improve chemical networks dealing with S-bearing species.
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Kotloff, Karen L., Marcelo B. Sztein, Steven S. Wasserman, Genevieve A. Losonsky, Susan C. DiLorenzo, and Richard I. Walker. "Safety and Immunogenicity of Oral Inactivated Whole-CellHelicobacter pylori Vaccine with Adjuvant among Volunteers with or without Subclinical Infection." Infection and Immunity 69, no. 6 (June 1, 2001): 3581–90. http://dx.doi.org/10.1128/iai.69.6.3581-3590.2001.
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ABSTRACT Helicobacter pylori infection of the gastric mucosa can be found in approximately 50% of the world's population and is associated with a range of pathology, including peptic ulcer, atrophic gastritis, and gastric cancer. To explore immunization as a strategy for preventing and treating H. pylori-associated disease, we assessed the safety and immunogenicity in healthy adults of a formalin-inactivated, oral H. pylori whole-cell (HWC) vaccine, administered with or without mutant Escherichia coli heat-labile toxin (LTR192G) as a mucosal adjuvant. In a dose-response study, 23 subjects with or withoutH. pylori infection were vaccinated with either 2.5 × 106 HWC, 2.5 × 108 HWC, or 2.5 × 1010 HWC, plus 25 μg of LTR192G. Thereafter, a randomized study was conducted in which 18 H. pylori-infected subjects were assigned, in a double-blind fashion, to receive either 2.5 × 1010 HWC plus placebo-adjuvant, placebo-vaccine plus 25 μg of LTR192G, placebo-vaccine plus placebo-adjuvant, or 2.5 × 1010 HWC plus 25 μg of LTR192G. Diarrhea (six subjects), low-grade fever (five subjects), and vomiting (two subjects) were observed, usually after the first dose. Significant rises in geometric mean mucosal (fecal and salivary) anti-HWC immunoglobulin A antibodies occurred amongH. pylori-infected and uninfected subjects following inoculation with 2.5 × 1010 HWC plus 25 μg of LTR192G. Moreover, among H. pylori-negative volunteers, this regimen induced significant lymphoproliferative responses in 5 of 10 subjects and gamma interferon production responses to H. pylori sonicate in 7 of 10 subjects. There was no evidence that vaccination eradicatedH. pylori in infected volunteers. These results suggest that it is possible to stimulate mucosal and systemic immune responses in humans to H. pylori antigens by using an HWC vaccine.
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Guo, Liangyan, Hongchao Cheng, Junfeng Chen, Wentao Chen, and Jingyao Zhao. "Pore structure characterization of oak via X-ray computed tomography." BioResources 15, no. 2 (March 16, 2020): 3053–63. http://dx.doi.org/10.15376/biores.15.2.3053-3063.
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The microscopic pore structure of wood is an important factor that affects its macroscopic properties. In this study, an oak sample was used for pore structure characterization. X-ray computed tomography imaging was carried out, and the scanning results (a multi-layer two-dimensional planar image) were rendered using Avizo software (a three-dimensional stereo image). A digital image processing method was used to identify the characteristics of the three-dimensional pore structure features and to calculate the characteristic parameters, i.e., the porosity (volume/surface), pore area and volume, pore size distribution, and the connectivity. The 27 mm3 oak sample had the following characteristics: a pore size which ranged from 8.56 µm to 1262.84 µm; a pore volume of 1.01 × 1010 µm3; a pore area and volume porosity of 1.12 × 109 µm2 and 37.6%, respectively; a surface porosity range of approximately 36.1% to 39.1%; a pore diameter for axial connection ranging from approximately 164.57 µm to 1262.84 µm; and had corresponding proportions of the pore area and volume of approximately 74.4% and 67.3%, respectively. This information provided useful structural data for the construction of future models.
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MICHALSKI, C. B., R. E. BRACKETT, Y. C. HUNG, and G. O. I. EZEIKE. "Use of Capillary Tubes and Plate Heat Exchanger to Validate U.S. Department of Agriculture Pasteurization Protocols for Elimination of Listeria monocytogenes in Liquid Egg Products." Journal of Food Protection 63, no. 7 (July 1, 2000): 921–25. http://dx.doi.org/10.4315/0362-028x-63.7.921.
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D-values for a five-strain cocktail of Listeria monocytogenes in five different liquid egg products (whole egg, egg yolk, egg white, egg yolk + 5% sucrose + 5% NaCl, and egg yolk + 10% NaCl) were determined using 100-μl capillary tubes. The egg products were inoculated with approximately 1 × 1010 organisms/ml and heated in capillary tubes to temperatures ranging from 53 to 69°C for various time intervals. Using a pilot scale plate heat exchanger, the U.S. Department of Agriculture (USDA) protocols for pasteurization were also evaluated using egg products inoculated with approximately 1 × 107 L. monocytogenes/ml. Results of experiments with capillary tubes suggested that all processes would result in less than the 9D process recommended by USDA. Moreover, although pasteurization with a plate heat exchanger provided greater lethality than did capillary tubes, all products still received less than a 5.4D process. Hence, these results suggest that the current USDA protocol may not be adequate to assure a large margin of safety.
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Nalivaiko, Oleg Yu, Arcady S. Turtsevich, Vladimir I. Plebanovich, and Peter I. Gaiduk. "Segregation-induced formation of Ge nanocrystals in silicon oxide." Journal of the Belarusian State University. Physics, no. 2 (June 15, 2022): 70–78. http://dx.doi.org/10.33581/2520-2243-2022-2-70-78.
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The investigation of initial stage of Si1 – xGex alloy deposition and clarification of Ge nanocrystal formation mechanism has been carried out. It was found that at the initial stages of growing layers of Si1 – xGex alloys, the density of island nuclei Si1 – xGex increases by a factor of 2.5–3.4 compared to the density of polycrystalline silicon islands (from 1.07 ⋅ 1011 to 1.90 ⋅ 1011 cm–2 and from 3.1 ⋅ 1010 to 4.3 ⋅ 1010 cm–2 respectively). A decrease in the thickness of the layer corresponding to the end of the induction period and the formation of a continuous Si1 – xGex layer to 8–10 nm (for polycrystalline silicon, the thickness of a similar layer is approximately 22 nm) has been established. It is shown that the Ge nanocrystal formation is occurred by segregationist pushback of Ge atoms by the SiO2 /Si1 – xGex oxidation front and oxidation through grain boundaries during oxidation of Si1 – xGex thin layers, produced by chemical vapor deposition. The MOS structure with array of Ge nanocrystal, which has the hysteresis capacitance characteristics of 1.7–1.8 V and leakage current density from 1.5 ⋅ 10–16 to 2.2 ⋅ 10–16 A/µm2 was obtained.
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Berresheim, H., C. Plass-Dülmer, T. Elste, N. Mihalopoulos, and F. Rohrer. "OH in the coastal boundary layer of Crete during MINOS: Measurements and relationship with ozone photolysis." Atmospheric Chemistry and Physics Discussions 3, no. 1 (February 27, 2003): 1183–212. http://dx.doi.org/10.5194/acpd-3-1183-2003.
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Abstract. Hydroxyl radical (OH) concentrations were measured in August 2001 at Finokalia Station on the northeastern coast of Crete during the Mediterranean Intensive Oxidant Study (MINOS). OH was measured based on selected ion chemical ionization mass spectrometry (SI/CIMS) with a time resolution of 30 s and signal integration of 5 min. The corresponding accuracy, precision, and detection limit were 20% (1s), 11% (1s), and 2.4×105 molecules cm−3 (2 s), respectively. OH levels showed a strong diurnal variability with high maxima (approximately 2×107 molecules cm−3) occurring around 13:30 LT (10:30 UTC) and nighttime values below the detection limit. Daily 24-hour average concentrations varied between 3.6–6.7×1016 cm−3. For the total measurement period (6–21 August) the mean and standard deviation were 4.5±1.1×106 cm−3. The OH data set is analyzed based on a classification into three periods: I: 6–8 August, II: 9–11 August, III: 13–18 August. For each of the three periods the measured OH concentrations are described by the empirical function [OH] = a J(O1D)0.68, with J(O1D) being the ozone photolysis frequency and a = 1.4×1010 s cm−3, 1.7×1010 s cm−3, and 2.2×1010 s cm−3, respectively. It is shown that this relationship is consistent with a CH4-CO box model yielding a corresponding exponent of 0.70. Taking into account the estimated precision of the OH measurements this empirical function explains 99% of the observed variance of OH.
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Perrey, Hanno, Mikael Elfman, Kevin Fissum, Robert J. W. Frost, Nathaly De La Rosa, Markus Kristensson, Per Kristiansson, et al. "From micro- to macro- neutron sources: The Lund Broad-band Neutron Facility." EPJ Web of Conferences 231 (2020): 01005. http://dx.doi.org/10.1051/epjconf/202023101005.
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The Lund Broad-band Neutron Facility provides access to a variety of neutron sources together with a well-established user infrastructure. Neutrons from radioactive sources have been successfully employed for the research and development of both detectors and materials for the European Spallation Source. A recently procured d-t neutron generator delivers higher neutron fluxes than those provided by the radioactive sources, and further allows for pulsed operation. With the currently on-going construction of a dedicated neutron beam-line at our 3 MeV Pelletron accelerator, the facility is anticipated to produce approximately 1010 n/s. Cost-effective access to neutrons as well as a platform for educational purposes are the ultimate goals of the project.
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Booth, Alison O., Catherine E. Huggins, Naiyana Wattanapenpaiboon, and Caryl A. Nowson. "Effect of increasing dietary calcium through supplements and dairy food on body weight and body composition: a meta-analysis of randomised controlled trials." British Journal of Nutrition 114, no. 7 (August 3, 2015): 1013–25. http://dx.doi.org/10.1017/s0007114515001518.
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This meta-analysis of randomised controlled trials assessed the effect of Ca on body weight and body composition through supplementation or increasing dairy food intake. Forty-one studies met the inclusion criteria (including fifty-one trial arms; thirty-one with dairy foods (n 2091), twenty with Ca supplements (n 2711). Ca intake was approximately 900 mg/d higher in the supplement groups compared with control. In the dairy group, Ca intake was approximately 1300 mg/d. Ca supplementation did not significantly affect body weight (mean change ( − 0·17, 95 % CI − 0·70, 0·37) kg) or body fat (mean change ( − 0·19, 95 % CI − 0·51, 0·13) kg) compared to control. Similarly, increased dairy food intake did not affect body weight ( − 0·06, 95 % CI − 0·54, 0·43) kg or body fat change ( − 0·36, 95 % CI − 0·80, 0·09) kg compared to control. Sub-analyses revealed that dairy supplementation resulted in no change in body weight (nineteen studies, n 1010) ( − 0·32, 95 % CI − 0·93, 0·30 kg, P= 0·31), but a greater reduction in body fat (thirteen studies, n 564) ( − 0·96, 95 % CI − 1·46, − 0·46 kg, P < 0·001) in the presence of energy restriction over a mean of 4 months compared to control. Increasing dietary Ca intake by 900 mg/d as supplements or increasing dairy intake to approximately 3 servings daily (approximately 1300 mg of Ca/d) is not an effective weight reduction strategy in adults. There is, however, an indication that approximately 3 servings of dairy may facilitate fat loss on weight reduction diets in the short term.
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Sayed, Zoda, M. Abdel-Rahman, M. A. Abdel-Rahman, and Emad A. Badawi. "Characterization of irradiation effect on 5251 Al-alloy using rietveld x-ray diffraction analysis." Physica Scripta 96, no. 12 (November 23, 2021): 125029. http://dx.doi.org/10.1088/1402-4896/ac387c.
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Abstract This work aims to study irradiation doses (0, 100, 200, 400, 600 and 1000 kGy of Co60 γ-source doses) effect on 5251 Al-alloy samples using XRD analysis. The main structures of the x-ray diffraction patterns are the same, a considerable difference in the peak intensities is observed due to the grain growth associated with increasing of irradiation doses. The intensity ratio of higher reflections declares that nearly 600 kGy irradiation dose is the preferred orientation or threshold point. Microstructure characterization has been studied using x-ray Diffraction Line Profile (XDLP) analysis. Minimum crystallite size of about 0.106 μm is measured for non-irradiated sample, maximum value is observed at 600 kGy. Micro-strain decreases exponentially with increasing irradiation dose, in addition the cell parameter seems to be constant. The dislocation and defect densities reveal the same behavior as the micro-strain. The defect and dislocation density decrease exponentially with increasing of irradiation doses with maximum values of about 1.10 × 1019 cm−3 and 3.15 × 1010 cm−2 respectively obtained for non-irradiation. The variation of the stored dislocation energy due to irradiation doses reveal maximum stored dislocation energy of about 334.95 kJ m−3 for non-irradiated sample, then it is approximately kept constant with increasing of irradiation dose up to 1000 kGy.
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Giechaskiel, Barouch, Athanasios Mamakos, Joseph Woodburn, Andrzej Szczotka, and Piotr Bielaczyc. "Evaluation of a 10 nm Particle Number Portable Emissions Measurement System (PEMS)." Sensors 19, no. 24 (December 14, 2019): 5531. http://dx.doi.org/10.3390/s19245531.
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On-board portable emissions measurement systems (PEMS) are part of the type approval, in-service conformity, and market surveillance aspects of the European exhaust emissions regulation. Currently, only solid particles >23 nm are counted, but Europe will introduce a lower limit of 10 nm. In this study, we evaluated a 10-nm prototype portable system comparing it with laboratory systems measuring diesel, gasoline, and CNG (compressed natural gas) vehicles with emission levels ranging from approximately 2 × 1010 to 2 × 1012 #/km. The results showed that the on-board system differed from the laboratory 10-nm system on average for the tested driving cycles by less than approximately 10% at levels below 6 × 1011 #/km and by approximately 20% for high-emitting vehicles. The observed differences were similar to those observed in the evaluation of portable >23 nm particle counting systems, despite the relatively small size of the emitted particles (with geometric mean diameters <42 nm) and the additional challenges associated with sub-23 nm measurements. The latter included the presence of semivolatile sub-23 nm particles, the elevated concentration levels during cold start, and also the formation of sub-23 nm artefacts from the elastomers that are used to connect the tailpipe to the measurement devices. The main conclusion of the study is that >10 nm on-board systems can be ready for introduction in future regulations.
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Gourgouliatos, Konstantinos N., Rainer Hollerbach, and Andrei P. Igoshev. "Powering central compact objects with a tangled crustal magnetic field." Monthly Notices of the Royal Astronomical Society 495, no. 2 (May 11, 2020): 1692–99. http://dx.doi.org/10.1093/mnras/staa1295.
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ABSTRACT Central Compact Objects (CCOs) are X-ray sources with luminosity ranging between 1032 and 1034 erg s−1, located at the centres of supernova remnants. Some of them have been confirmed to be neutron stars. Timing observations have allowed the estimation of their dipole magnetic field, placing them in the range ∼1010–1011 G. The decay of their weak dipole fields, mediated by the Hall effect and Ohmic dissipation, cannot provide sufficient thermal energy to power their X-ray luminosity, as opposed to magnetars whose X-ray luminosities are comparable. Motivated by the question of producing high X-ray power through magnetic field decay while maintaining a weak dipole field, we explore the evolution of a crustal magnetic field that does not consist of an ordered axisymmetric structure, but rather comprises a tangled configuration. This can be the outcome of a non-self-excited dynamo, buried inside the crust by fallback material following the supernova explosion. We find that such initial conditions lead to the emergence of the magnetic field from the surface of the star and the formation of a dipolar magnetic field component. An internal tangled magnetic field of the order of 1014 G can provide sufficient Ohmic heating to the crust and power CCOs, while the dipole field it forms is approximately 1010 G, as observed in CCOs.
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Xue, L., R. Reininger, Y. Q. Wu, Y. Zou, Z. M. Xu, Y. B. Shi, J. Dong, et al. "Design of an ultrahigh-energy-resolution and wide-energy-range soft X-ray beamline." Journal of Synchrotron Radiation 21, no. 1 (December 11, 2013): 273–79. http://dx.doi.org/10.1107/s1600577513029093.
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A new ultrahigh-energy-resolution and wide-energy-range soft X-ray beamline has been designed and is under construction at the Shanghai Synchrotron Radiation Facility. The beamline has two branches: one dedicated to angle-resolved photoemission spectroscopy (ARPES) and the other to photoelectron emission microscopy (PEEM). The two branches share the same plane-grating monochromator, which is equipped with four variable-line-spacing gratings and covers the 20–2000 eV energy range. Two elliptically polarized undulators are employed to provide photons with variable polarization, linear in every inclination and circular. The expected energy resolution is approximately 10 meV at 1000 eV with a flux of more than 3 × 1010 photons s−1at the ARPES sample positions. The refocusing of both branches is based on Kirkpatrick–Baez pairs. The expected spot sizes when using a 10 µm exit slit are 15 µm × 5 µm (horizontal × vertical FWHM) at the ARPES station and 10 µm × 5 µm (horizontal × vertical FWHM) at the PEEM station. The use of plane optical elements upstream of the exit slit, a variable-line-spacing grating and a pre-mirror in the monochromator that allows the influence of the thermal deformation to be eliminated are essential for achieving the ultrahigh-energy resolution.
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Kubota, Aya, Tadayasu Dotani, Jean Cottam, Taro Kotani, Chris Done, Yoshihiro Ueda, Andy C. Fabian, et al. "Suzaku observation of the black hole transient 4U1630–472: discovery of absorption lines." Proceedings of the International Astronomical Union 2, S238 (August 2006): 23–28. http://dx.doi.org/10.1017/s1743921307004620.
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AbstractWe present the results of six Suzaku observations of the recurrent black hole transient 4U 1630–472 during its decline from its most recent outburst in 2006. All observations show the typical high/soft state spectral shape in the 2–50 keV band, roughly described by an optically thick disk spectrum in the soft energy band plus a weak power-law tail.The disk temperature decreases from 1.4 keV to 1.2 keV as the flux decreases by a factor 2, consistent with a constant radius as expected for disk-dominated spectra. All the observations reveal significant absorption lines from highly ionized (H-like and He-like) iron Kα at 7.0 keV and 6.7 keV.The energies of these absorption lines suggest a blue shift with an outflow velocity of ∼1000 km s−1. The H–like iron Kα equivalent width remains approximately constant at ∼30 eV over all the observations, while that of the He–like Kα line increases from 7 eV to 20 eV. Thus the ionization state of the material decreases, as expected from the decline in flux.The data constrain the velocity dispersion of the absorber to 200–2000 km s−1, and the size of the plasma as ∼1010 cm assuming a source distance of 10 kpc.
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Hirayama, H., Y. Aoyagi, and S. Tanaka. "Fabrication of Self-Assembling AlGaN Quantum Dot on AlGaN Surfaces Using Anti-Surfactant." MRS Internet Journal of Nitride Semiconductor Research 4, S1 (1999): 852–57. http://dx.doi.org/10.1557/s1092578300003525.
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We report on the first artificial fabrication of self-assembling AlGaN quantum dots (QDs) on AlGaN surfaces using metal organic chemical vapor deposition (MOCVD). The AlGaN QDs are fabricated using a growth mode change from 2-dimensional step-flow growth to 3-dimensional island formation by modifying the AlGaN surface energy with Si anti-surfactant. The average lateral size and the thickness of fabricated AlGaN QDs, as determined by AFM, are approximately 20 nm and 6nm, respectively. The dot density was found to be controlled from 5×1010 cm−2 down to 2×109 cm−2 by increasing the dose of Si anti-surfactant. We obtained the photoluminescence (PL) from AlGaN QDs embedded with Al0.38Ga0.62N capping layers. The Al incorporation in AlGaN QDs was controllable within the range of 1-5 %.
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Zhang, T., F. H. Sun, Bin Shen, and Z. M. Zhang. "CVD Micron Diamond Powders." Advanced Materials Research 797 (September 2013): 495–99. http://dx.doi.org/10.4028/www.scientific.net/amr.797.495.
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The conventional diamond powders (< 10 μm) are generally produced from crushing the large-sized diamonds synthesized by high-pressure and high-temperature (HPHT) technique, whereas they have many morphological imperfections. In the present work, the hot filament chemical vapour deposition (HFCVD) technique is employed for synthesizing such diamond powders. A great many of micron diamonds are grown simultaneously but independently onto a large-area substrate. First, the seeds with an appropriate density approximately 1.3×1010 m-2 are dispersed evenly onto a mirror-polished silicon wafer by using a spin coater machine. Afterwards, the regrowth mechanism of seeds is mainly discussed. The results demonstrate that the unwanted spontaneous and secondary nucleation play a determinant role in keeping well in the morphology of crystals and inhibiting the poly-crystals growth.
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Foschini, Cesar, Bruno Hangai, Paulo Ortega, Elson Longo, Mário Cilense, and Alexandre Simões. "Evidence of ferroelectric behaviour in CaCu3Ti4O12 thin films deposited by RF-sputtering." Processing and Application of Ceramics 13, no. 3 (2019): 219–28. http://dx.doi.org/10.2298/pac1903219f.
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The origin of abnormal ferroelectric and unusual piezoelectricity in the polycrystalline CaCu3Ti4O12 (CCTO) thin films deposited by RF-sputtering on Pt/Ti/SiO2/Si (100) substrates was explored. The CCTO thin films, deposited at room temperature followed by annealing at 600?C for 2 h in a conventional furnace, have a cubic structure with lattice parameter a = 7.379 ? 0.001 ? and without any secondary phases. No polarization loss up to 1010 switching cycles, with a switched polarization ?P of 30 ?C/cm2 measured at 400 kV/cm was evidenced. The piezoelectric coefficient investigated by piezoresponse force microscopy (PFM) was approximately 9.0 pm/V. This may be the very first example of exploring the origin of ferroelectric behaviour for a material that possesses space charge polarization with highly resistive grain boundaries in the polycrystalline state.
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Kubisztal, Julian, Bożena Łosiewicz, Paulina Dybal, Violetta Kozik, and Andrzej Bak. "Temperature-Related Corrosion Resistance of AISI 1010 Carbon Steel in Sulfolane." Materials 13, no. 11 (June 4, 2020): 2563. http://dx.doi.org/10.3390/ma13112563.
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Sulfolane-induced corrosion can lead to severe impairment in industrial systems. Therefore, determination of solvent corrosivity is valid. Under standard conditions, pure sulfolane is considered to be thermally stable and chemically inert, hence non-aggressive towards carbon/stainless steel. Unfortunately, the sulfolane-evoked corrosion of the industrial installations is observed for sulfolane-based systems polluted by small quantities of oxygen, water and some oxidizing agents. Moreover, sulfolane decomposition with formation of corrosive (by-)products can be escalated by some process parameters, e.g., temperature. The main objective of this study was to determine the corrosion resistance of AISI 1010 steel immersed in sulfolane at temperatures ranging from 25 to 230 °C. Evaluation of the corrosion damage was carried out using electrochemical techniques and scanning probe/electron microscopy, respectively. The general corrosion tendency, corrosion rate and surface corrosion degree were taken into account as well. It was noticed that the corrosion rate linearly increases with the enhancement of sulfolane temperature. Moreover, the interfacial reaction of steel with sulfolane resulted in the formation of corrosion product layer, which is a physical barrier between the corrosive environment and steel improving corrosion resistance of the latter. In fact, the increment of the sulfolane temperature caused a gradual breakdown of the protective layer and the increase in the corrosion degree of the investigated steel. Finally, it was found that the corrosion degree doubles approximately every 42 °C.
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Van Dorssen, G. E., E. Louis, and F. Bijkerk. "Optimization of X-ray emission from a laser-produced plasma in a narrow wavelength band." Laser and Particle Beams 10, no. 4 (December 1992): 759–65. http://dx.doi.org/10.1017/s0263034600004705.
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The X-ray emission from laser-produced plasmas at an X-ray wavelength of approximately 10.4 nm was measured for Al and Gd target materials. The laser power density on the target surface was varied between 1.5 × 1010 and 3 × 1012 W/cm2 to obtain different electron temperatures. The output from the plasma was measured using an X-ray reflecting Pd-C multilayer coating as a wavelength-selective element and a diamond photoconductive detector. The emission at 10.4 nm is strongest at the low end of the power density range investigated. A strong increase is found for Al targets due to a contribution of line radiation, which is not present in the Gd plasmas. The measured conversion efficiency for Al plasmas was (4.5 ± 1)% in a 3% bandwidth at an X-ray wavelength of 10.4 nm.
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Spence, J. C. H., W. Qian, J. Liu, and W. Lo. "Experimental low-voltage-point projection microscopy." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 1060–61. http://dx.doi.org/10.1017/s0424820100151131.
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The remarkable achievement of atomic resolution by low voltage point projection microscopy has revived interest in this instrument, and, since resolution is approximately equal to virtual source size, demonstrates field-emission from tip regions of atomic dimensions. Ray-tracing calculations show the aberration coefficients and size of the virtual source to be subnanometer. The brightness of such a nanotip has been measured to be 7.7 × 1010 A cm -2 sr -1 (at 100 kV), somewhat greater than conventional cold field emitters or synchrotrons. The images require the theory of transmission LEED for interpretation and are always out of focus by the tip to sample distance zl. Their relationship to HREM images and coherent CBED is discussed elsewhere The instruments hold promise for imaging small organic molecules (across holey carbon grids), LB and other thin organic films where radiation damage is dominated by inner-shell processes.
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Newbury, D. E., and R. D. Leapman. "Trace nanoanalysis." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 940–41. http://dx.doi.org/10.1017/s0424820100172437.
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Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).
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Olsen, S. C., and S. G. Hennager. "Immune Responses and Protection against Experimental Brucella suis Biovar 1 Challenge in Nonvaccinated or B. abortus Strain RB51-Vaccinated Cattle." Clinical and Vaccine Immunology 17, no. 12 (October 13, 2010): 1891–95. http://dx.doi.org/10.1128/cvi.00326-10.
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ABSTRACT Twenty Hereford heifers approximately 9 months of age were vaccinated with saline (control) or 2 × 1010 CFU of the Brucella abortus strain RB51 (RB51) vaccine. Immunologic responses after inoculation demonstrated significantly greater (P < 0.05) antibody and proliferative responses to RB51 antigens in cattle vaccinated with RB51 than in the controls. Pregnant cattle received a conjunctival challenge at approximately 6 months of gestation with 107 CFU of B. suis bv. 1 strains isolated from naturally infected cattle. The fluorescence polarization assay and the buffered acid plate agglutination test had the highest sensitivities in detecting B. suis-infected cattle between 2 and 12 weeks after experimental infection. Serologic responses and lymphocyte proliferative responses to B. suis antigens did not differ between control and RB51 vaccinees after experimental infection. No abortions occurred in cattle in either treatment group after challenge, although there appeared to be an increased incidence of retained placenta after parturition in both the control and the RB51 vaccination treatment groups. Our data suggest that the mammary gland is a preferred site for B. suis localization in cattle. Vaccination with RB51 did not reduce B. suis infection rates in maternal or fetal tissues. In conclusion, although B. suis is unlikely to cause abortions and fetal losses in cattle, our data suggest that RB51 vaccination will not protect cattle against B. suis infection after exposure.
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Hornbach, Matthew J., W. Steven Holbrook, Andrew R. Gorman, Kara L. Hackwith, Daniel Lizarralde, and Ingo Pecher. "Direct seismic detection of methane hydrate on the Blake Ridge." GEOPHYSICS 68, no. 1 (January 2003): 92–100. http://dx.doi.org/10.1190/1.1543196.
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Seismic detection of methane hydrate often relies on indirect or equivocal methods. New multichannel seismic reflection data from the Blake Ridge, located approximately 450 km east of Savannah, Georgia, show three direct seismic indicators of methane hydrate: (1) a paleo bottom‐simulating reflector (BSR) formed when methane gas froze into methane hydrate on the eroding eastern flank of the Blake Ridge, (2) a lens of reduced amplitudes and high P‐wave velocities found between the paleo‐BSR and BSR, and (3) bright spots within the hydrate stability zone that represent discrete layers of concentrated hydrate formed by upward migration of gas. Velocities within the lens (∼1910 m/s) are significantly higher than velocities in immediately adjacent strata (1820 and 1849 m/s). Conservative estimates show that the hydrate lens contains at least 13% bulk methane hydrate within a 2‐km3 volume, yielding 3.2 × 1010kg [1.5 TCF (4.2 × 1010 m3] of methane. Low seismic amplitudes coupled with high interval velocities within the lens offer evidence for possible methane hydrate “blanking.” Hydrate bright spots yield velocities as high as 2100 m/s, with bulk hydrate concentrations predicted as high as 42% in an approximately 15‐m thick layer. Our results show that, under certain circumstances, hydrate in marine sediments can be directly detected in seismic reflections but that quantification of hydrate concentrations requires accurate velocity information.
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Farnós, Omar, Esayas Gelaye, Khaled Trabelsi, Alice Bernier, Kumar Subramani, Héla Kallel, Martha Yami, and Amine A. Kamen. "Establishing a Robust Manufacturing Platform for Recombinant Veterinary Vaccines: An Adenovirus-Vector Vaccine to Control Newcastle Disease Virus Infections of Poultry in Sub-Saharan Africa." Vaccines 8, no. 2 (June 26, 2020): 338. http://dx.doi.org/10.3390/vaccines8020338.
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Developing vaccine technology platforms to respond to pandemic threats or zoonotic diseases is a worldwide high priority. The risk of infectious diseases transmitted from wildlife and domestic animals to humans makes veterinary vaccination and animal health monitoring highly relevant for the deployment of public health global policies in the context of “one world, one health” principles. Sub-Saharan Africa is frequently impacted by outbreaks of poultry diseases such as avian influenza and Newcastle Disease (ND). Here, an adenovirus-vectored vaccine technology platform is proposed for rapid adaptation to ND or other avian viral threats in the region. Ethiopian isolates of the Newcastle Disease virus (NDV) were subjected to sequence and phylogenetic analyses, enabling the construction of antigenically matched vaccine candidates expressing the fusion (F) and hemagglutinin-neuraminidase (HN) proteins. A cost-effective vaccine production process was developed using HEK293 cells in suspension and serum-free medium. Productive infection in bioreactors (1–3 L) at 2 × 106 cells/mL resulted in consistent infectious adenoviral vector titers of approximately 5–6 × 108 TCID50/mL (approximately 1011VP/mL) in the harvest lysates. Groups of chickens were twice immunized with 1 × 1010 TCID50 of the vectors, and full protection against a lethal NDV challenge was provided by the vector expressing the F antigen. These results consolidate the basis for a streamlined and scalable-vectored vaccine manufacturing process for deployment in low- and medium-income countries.
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Montilla, Rafael, M. A. R. Chowdhury, A. Huq, B. Xu, and Rita R. Colwell. "Serogroup conversion of Vibrio cholerae non-O1 to Vibrio cholerae O1: effect of growth state of cells, temperature, and salinity." Canadian Journal of Microbiology 42, no. 1 (January 1, 1996): 87–93. http://dx.doi.org/10.1139/m96-014.
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Recently, we reported the occurrence of seroconversion from Vibrio cholerae non-O1 to V. cholerae O1, but little is known about the environmental and physiological factors influencing seroconversion. We investigated effects of temperature (4, 25, and 35 °C) and salinity (<0.5 and 10‰), as well as the stage of growth of cells, on serogroup conversion. Seroconversion of V. cholerae occurred under various environmental conditions. However, the rate of seroconversion in natural water (<0.5‰ salinity) and synthetic seawater microcosms (10‰ salinity), employing cells harvested from stationary phase culture, was approximately 2 logs higher than cells harvested from cultures in the logarithmic phase (i.e., 105 versus 103 per 1010 cells). Thus, the physiological state of the cells, and to a lesser degree, temperature and salinity, is an important factor in the conversion of V. cholerae from non-O1 to O1 serogroup.Key words: Vibrio cholerae O1, Vibrio cholerae non-O1, growth stage, serogroup conversion.
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Arimi, S. M., C. R. Fricker, and R. W. A. Park. "Occurrence of ‘thermophilic’ campylobacters in sewage and their removal by treatment processes." Epidemiology and Infection 101, no. 2 (October 1988): 279–86. http://dx.doi.org/10.1017/s0950268800054194.
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SUMMARYRemoval of thermophilic campylobacters from sewage at three different stages of treatment at a trickling filter sewage works has been assessed. Samples of incoming sewage, primary sedimentation effluent and final effluent were taken daily from 06.00 h to 20.00 h for 5 consecutive days and the numbers of campylobacters determined by using a most probable number method. Each sample was cultured using 2 h pre–enrichment followed by enrichment in Preston broth for 48 h and detection by plating. Over 78% of the incoming campylobacters were removed after primary sedimentation and < 0.1% remained in the final effluent.Campylobacter jejunbiotype I and biotype II constituted 81.5% and 15.9% respectively of the 232 isolates tested. Serotypes common in sewage were common in human faces. It appears that the trickling filter sewage works removes most of the campylobacters entering the sewage works, but large numbers, estimated to be approximately 1010, are released into the environment daily from a local sewage works.
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Dos Santos, Leonardo A., Aline A. Vidotto, Shreyas Vissapragada, Munazza K. Alam, Romain Allart, Vincent Bourrier, James Kirk, Julia V. Seidel, and David Ehrenreich. "p-winds: An open-source Python code to model planetary outflows and upper atmospheres." Astronomy & Astrophysics 659 (March 2022): A62. http://dx.doi.org/10.1051/0004-6361/202142038.
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Atmospheric escape is considered to be one of the main channels for evolution in sub-Jovian planets, particularly in their early lives. While there are several hypotheses proposed to explain escape in exoplanets, testing them with atmospheric observations remains a challenge. In this context, high-resolution transmission spectroscopy of transiting exoplanets for the metastable helium triplet (He 23S) at 1083 nm has emerged as a reliable technique for observing and measuring escape. To aid in the prediction and interpretation of metastable He transmission spectroscopy observations, we developed the code p-winds. This is an open-source, fully documented, scalable Python implementation of the one-dimensional, purely H+He Parker wind model for upper atmospheres coupled with ionization balance, ray-tracing, and radiative transfer routines. We demonstrate an atmospheric retrieval by fitting p-winds models to the observed metastable He transmission spectrum of the warm Neptune HAT-P-11 b and take the variation in the in-transit absorption caused by transit geometry into account. For this planet, our best fit yields a total atmospheric escape rate of approximately 2.5 × 1010 g s−1 and an outflow temperature of 7200 K. The range of retrieved mass loss rates increases significantly when we let the H atom fraction be a free parameter, but its posterior distribution remains unconstrained by He observations alone. The stellar host limb darkening does not have a significant impact on the retrieved escape rate or outflow temperature for HAT-P-11 b. Based on the non-detection of escaping He for GJ 436 b, we are able to rule out total escape rates higher than 3.4 × 1010 g s−1 at 99.7% (3σ) confidence.
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Huško, Filip, Cedric G. Lacey, and Carlton M. Baugh. "Statistics of galaxy mergers: bridging the gap between theory and observation." Monthly Notices of the Royal Astronomical Society 509, no. 4 (November 23, 2021): 5918–37. http://dx.doi.org/10.1093/mnras/stab3324.
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ABSTRACT We present a study of galaxy mergers up to z = 10 using the Planck Millennium cosmological dark matter simulation and the GALFORM semi-analytical model of galaxy formation. Utilizing the full 800 Mpc3 volume of the simulation, we studied the statistics of galaxy mergers in terms of merger rates and close pair fractions. We predict that merger rates begin to drop rapidly for high-mass galaxies (M* > 1011.3–1010.5 M⊙ for z = 0–4), as a result of the exponential decline in the galaxy stellar mass function. The predicted merger rates for massive galaxies (M* > 1010 M⊙) increase and then turn over with increasing redshift, by z = 3.5, in disagreement with hydrodynamical simulations and semi-empirical models. In agreement with most other models and observations, we find that close pair fractions flatten or turn over at some redshift (dependent on the mass selection). We conduct an extensive comparison of close pair fractions, and highlight inconsistencies among models, but also between different observations. We provide a fitting formula for the major merger time-scale for close galaxy pairs, in which the slope of the stellar mass dependence is redshift dependent. This is in disagreement with previous theoretical results that implied a constant slope. Instead, we find a weak redshift dependence only for massive galaxies (M* > 1010 M⊙): in this case the merger time-scale varies approximately as $M_*^{-0.55}$. We find that close pair fractions and merger time-scales depend on the maximum projected separation as $r_\mathrm{max}^{1.32}$, in agreement with observations of small-scale clustering of galaxies.
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Maitland, C. F., C. E. Buckley, B. H. O'Connor, P. D. Butler, and R. D. Hart. "Characterization of the pore structure of metakaolin-derived geopolymers by neutron scattering and electron microscopy." Journal of Applied Crystallography 44, no. 4 (July 13, 2011): 697–707. http://dx.doi.org/10.1107/s0021889811021078.
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The pore–solid structure of selected high-compressive-strength metakaolin geopolymers has been characterized to facilitate quantitative prediction of their physical properties. Geopolymers are multiphase materials with pore widths ranging from subnanometre to several tenths of a millimetre. Ultramicrotoming of resin-embedded grains was found to be an effective method for producing electron-transparent sections. Scanning and transmission electron microscopy showed the existence of a bi-level pore system and heterogeneity of the pore morphology. Ultra-small-angle neutron scattering, of sufficiently thin specimens, was found to be useful in detecting the length scales on which statistically significant structural changes occur as the geopolymer chemical composition is varied. Contrast variation experiments confirmed that the small-angle neutron scattering from an Si:Al:Na = 2.5:1:1.2 geopolymer before and after dehydration was dominated by scattering from pores. These experiments suggested the presence of closed (under current experimental conditions) pores in the dehydrated geopolymer. A three-phase analysis was developed for this system, and the scattering of the solid, open pore and closed pore phases was determined as a function of scattering length density ρ. The scattering from all three phases had the sameqdependence over the range of likely ρ within the uncertainties. A lower limit of 4.21 (6) × 1010 cm−2was determined for the scattering length density ρwof the nondehydrated geopolymer by assuming the pore fluid to be water. This scattering length density is significantly higher than the expected value of approximately 3.4 × 1010 cm−2. Small-angle neutron scattering from the dehydrated and nondehydrated Si:Al:Na = 2.5:1:1.2 geopolymer showed that dehydration does not cause a severe change in morphology of the nanoporosity on the length scale probed.
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Coster, T. S., M. K. Wolf, E. R. Hall, F. J. Cassels, D. N. Taylor, C. T. Liu, F. C. Trespalacios, A. DeLorimier, D. R. Angleberger, and C. E. McQueen. "Immune Response, Ciprofloxacin Activity, and Gender Differences after Human Experimental Challenge by Two Strains of Enterotoxigenic Escherichia coli." Infection and Immunity 75, no. 1 (October 30, 2006): 252–59. http://dx.doi.org/10.1128/iai.01131-06.
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ABSTRACT In order to test vaccines against enterotoxigenic Escherichia coli (ETEC)-induced diarrhea, challenge models are needed. In this study we compared clinical and immunological responses after North American volunteers were orally challenged by two ETEC strains. Groups of approximately eight volunteers received 109 or 1010 CFU of E. coli B7A (LT+ ST+ CS6+) or 108 or 109 CFU of E. coli H10407 (LT+ ST+ CFA/I+). About 75% of the volunteers developed diarrhea after challenge with 1010 CFU B7A or either dose of H10407. B7A had a shorter incubation period than H10407 (P = 0.001) and caused milder illness; the mean diarrheal output after H10407 challenge was nearly twice that after B7A challenge (P = 0.01). Females had more abdominal complaints, and males had a higher incidence of fever. Ciprofloxacin generally diminished or stopped symptoms and shedding by the second day of antibiotic treatment, but four subjects shed for one to four additional days. The immune responses to colonization factors CS6 and colonization factor antigen I (CFA/I) and to heat-labile toxin (LT) were measured. The responses to CFA/I were the most robust responses; all volunteers who received H10407 had serum immunoglobulin A (IgA) and IgG responses, and all but one volunteer had antibody-secreting cell (ASC) responses. One-half the volunteers who received B7A had an ASC response to CS6, and about one-third had serum IgA or IgG responses. Despite the differences in clinical illness and immune responses to colonization factors, the immune responses to LT were similar in all groups and were intermediate between the CFA/I and CS6 responses. These results provide standards for immune responses after ETEC vaccination.
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Jonšta, Petr, Vladislav Kurka, Marek Vindyš, and Ladislav Kander. "The Effect of Forging Conditions on Final Macrostructure of Slab Ingot from the 55NiCrMoV7 Tool Steel." Metals 11, no. 3 (March 6, 2021): 435. http://dx.doi.org/10.3390/met11030435.
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The paper presents numerical modelling and an operational experiment to forge a slab ingot P40N from 55NiCrMoV7 tool steel and the procedure for the optimization of its production. The aim of the numerical simulation of forging was to verify the existing procedure of forging a plate from a conventional polygonal 8K forging ingot and a slab ingot with a polygonal shape of P40N surfaces. The effect of the shape of the ingot on the achievement of the required forging reduction and strain after the cross section of the forging of the plate, with final dimensions of approximately 1010 mm width × 310 mm thickness × 5350 mm length, was studied. The results obtained in the operational experiment showed satisfactory qualitative parameters of the steel forging from the slab P40N ingot which were in accordance with the predicted results of numerical simulations. The results indicated that in selected cases the use of a slab P40N ingot instead of the conventional polygonal 8K forging ingot can be considered in the production of certain plate-type forgings.
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León-Patiño, C. A., E. A. Aguilar-Reyes, and C. Ruiz-Aguilar. "Fabrication and Characterization of Highly Ordered Porous Alumina Templates by a Two-Step Anodization Process." Materials Science Forum 755 (April 2013): 75–81. http://dx.doi.org/10.4028/www.scientific.net/msf.755.75.
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Highly ordered through-hole anodic porous alumina membranes were fabricated by electrochemical oxidation of aluminum in a controlled two-step process. A teflon dispositive was used to ensure single side anodization. Under the most appropriate condition for the fabrication of ideally ordered anodic aluminum oxide (AAO), the voltage used was 15 V during 24 h in a 15 % w/v sulfuric acid solution. SEM, TEM and FESEM characterization shows that the as-fabricated AAO film has a defect-free array of straight parallel channels perpendicular to the surface. The thickness of the porous membrane is 20 microns, approximately. The ordered channels are formed in a honey comb arrange with a pore diameter in the range 20-30 nm, wall thickness of 10-20 nm, interpore distance of 40 nm, and high aspect ratio of 850. The pore density, quantified by image analysis, is 5.4×1010 pore/cm2; perfect ordering was maintained in the full depth of the membrane. Dimensions of this porous structure provide a convenient way to precision engineer the nanoscale morphology.
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Mitsuyasu, Ronald T., Peter A. Anton, Steven G. Deeks, David T. Scadden, Elizabeth Connick, Matthew T. Downs, Andreas Bakker, et al. "Prolonged survival and tissue trafficking following adoptive transfer of CD4ζ gene-modified autologous CD4+ and CD8+ T cells in human immunodeficiency virus–infected subjects." Blood 96, no. 3 (August 1, 2000): 785–93. http://dx.doi.org/10.1182/blood.v96.3.785.
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Abstract We have genetically engineered CD4+ and CD8+ T cells with human immunodeficiency virus (HIV) specificity by inserting a gene, CD4ζ, containing the extracellular domain of human CD4 (which binds HIV env) linked to the zeta (ζ) chain of the T-cell receptor (which mediates T-cell activation). Twenty-four HIV-positive subjects received a single infusion of 2 to 3 × 1010 autologous CD4ζ-modified CD4+and CD8+ T cells administered with (n = 11) or without (n = 13) interleukin-2 (IL-2). Subjects had CD4 counts greater than 50/μL and viral loads of at least 1000 copies/mL at entry. T cells were costimulated ex vivo through CD3 and CD28 and expanded for approximately 2 weeks. CD4ζ was detected in 1% to 3% of blood mononuclear cells at 8 weeks and 0.1% at 1 year after infusion, and survival was not enhanced by IL-2. Trafficking of gene-modified T cells to bulk rectal tissue and/or isolated lamina propria lymphocytes was documented in a subset of 5 of 5 patients at 14 days and 2 of 3 at 1 year. A greater than 0.5 log mean decrease in rectal tissue–associated HIV RNA was observed for at least 14 days, suggesting compartmental antiviral activity of CD4ζ T cells. CD4+ counts increased by 73/μL at 8 weeks in the group receiving IL-2. There was no significant mean change in plasma HIV RNA or blood proviral DNA in either treatment arm. This sustained, high-level persistence of gene-modified T cells demonstrates the feasibility of ex vivo T-cell gene therapy in HIV-infected adults and suggests the importance of providing HIV-specific T-helper function.
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Mitsuyasu, Ronald T., Peter A. Anton, Steven G. Deeks, David T. Scadden, Elizabeth Connick, Matthew T. Downs, Andreas Bakker, et al. "Prolonged survival and tissue trafficking following adoptive transfer of CD4ζ gene-modified autologous CD4+ and CD8+ T cells in human immunodeficiency virus–infected subjects." Blood 96, no. 3 (August 1, 2000): 785–93. http://dx.doi.org/10.1182/blood.v96.3.785.015k10_785_793.
Full textAbstract:
We have genetically engineered CD4+ and CD8+ T cells with human immunodeficiency virus (HIV) specificity by inserting a gene, CD4ζ, containing the extracellular domain of human CD4 (which binds HIV env) linked to the zeta (ζ) chain of the T-cell receptor (which mediates T-cell activation). Twenty-four HIV-positive subjects received a single infusion of 2 to 3 × 1010 autologous CD4ζ-modified CD4+and CD8+ T cells administered with (n = 11) or without (n = 13) interleukin-2 (IL-2). Subjects had CD4 counts greater than 50/μL and viral loads of at least 1000 copies/mL at entry. T cells were costimulated ex vivo through CD3 and CD28 and expanded for approximately 2 weeks. CD4ζ was detected in 1% to 3% of blood mononuclear cells at 8 weeks and 0.1% at 1 year after infusion, and survival was not enhanced by IL-2. Trafficking of gene-modified T cells to bulk rectal tissue and/or isolated lamina propria lymphocytes was documented in a subset of 5 of 5 patients at 14 days and 2 of 3 at 1 year. A greater than 0.5 log mean decrease in rectal tissue–associated HIV RNA was observed for at least 14 days, suggesting compartmental antiviral activity of CD4ζ T cells. CD4+ counts increased by 73/μL at 8 weeks in the group receiving IL-2. There was no significant mean change in plasma HIV RNA or blood proviral DNA in either treatment arm. This sustained, high-level persistence of gene-modified T cells demonstrates the feasibility of ex vivo T-cell gene therapy in HIV-infected adults and suggests the importance of providing HIV-specific T-helper function.
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Hashimi, Aina Shasha, Muhammad Amirul Nazhif Mohd Nohan, Siew Xian Chin, Sarani Zakaria, and Chin Hua Chia. "Rapid Catalytic Reduction of 4-Nitrophenol and Clock Reaction of Methylene Blue using Copper Nanowires." Nanomaterials 9, no. 7 (June 28, 2019): 936. http://dx.doi.org/10.3390/nano9070936.
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Copper nanowires (CuNWs) with a high aspect ratio of ~2600 have been successfully synthesized by using a facile hydrothermal method. The reductions of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and methylene blue (MB) to leucomethylene blue (LMB) by using sodium borohydride (NaBH4) were used as models to test the catalytic activity of CuNWs. We showed that by increasing the CuNWs content, the rate of reduction increased as well. The CuNWs showed an excellent catalytic performance where 99% reduction of 4-NP to 4-AP occurred in just 60 s by using only 0.1 pg of CuNWs after treatment with glacial acetic acid (GAA). The rate constant (kapp) and activity factor (K) of this study is 18 and ~1010 fold in comparison to previous study done with no GAA treatment applied, respectively. The CuNWs showed an outstanding catalytic activity for at least ten consecutive reusability tests with a consistent result in 4-NP reduction. In clock reaction of MB, approximately 99% of reduction of MB into LMB was achieved in ~5 s by using 2 μg CuNWs. Moreover, the addition of NaOH can improve the rate and degree of recolorization of LMB to MB.
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Feruglio, C., F. Fiore, S. Carniani, R. Maiolino, V. D’Odorico, A. Luminari, P. Barai, et al. "The dense molecular gas in the z ∼ 6 QSO SDSS J231038.88+185519.7 resolved by ALMA." Astronomy & Astrophysics 619 (November 2018): A39. http://dx.doi.org/10.1051/0004-6361/201833174.
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We present ALMA observations of the CO(6-5) and [CII] emission lines and the sub-millimeter continuum of the z ∼ 6 quasi-stellar object (QSO) SDSS J231038.88+185519.7. Compared to previous studies, we have analyzed a synthetic beam that is ten times smaller in angular size, we have achieved ten times better sensitivity in the CO(6-5) line, and two and half times better sensitivity in the [CII] line, enabling us to resolve the molecular gas emission. We obtain a size of the dense molecular gas of 2.9 ± 0.5 kpc, and of 1.4 ± 0.2 kpc for the 91.5 GHz dust continuum. By assuming that CO(6-5) is thermalized, and by adopting a CO to H2 conversion factor αCO = 0.8 M⊙K−1 (km s)−1 pc2, we infer a molecular gas mass of M(H2) = (3.2±0.2)×1010 M⊙. Assuming that the observed CO velocity gradient is due to an inclined rotating disk, we derive a dynamical mass of Mdynsin2(i)=(2.4 ± 0.5)×1010 M⊙, which is a factor of approximately two smaller than the previously reported estimate based on [CII]. Regarding the central black hole, we provide a new estimate of the black hole mass based on the C IV emission line detected in the VLT/X-shooter spectrum: MBH = (1.8 ± 0.5)×109 M⊙. We find a molecular gas fraction of μ = M(H2)/M* ∼ 4.4, where M∗ ≈ Mdyn − M(H2) − M(BH). We derive a ratio νrot/σ ≈ 1 − 2 suggesting high gas turbulence, outflows/inflows and/or complex kinematics due to a merger event. We estimate a global Toomre parameter Q ∼ 0.2 − 0.5, indicating likely cloud fragmentation. We compare, at the same angular resolution, the CO(6-5) and [CII] distributions, finding that dense molecular gas is more centrally concentrated with respect to [CII]. We find that the current BH growth rate is similar to that of its host galaxy.
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La Ragione, R. M., N. MY Ahmed, A. Best, D. Clifford, U. Weyer, W. A. Cooley, L. Johnson, G. R. Pearson, and M. J. Woodward. "Colonization of 8-week-old conventionally reared goats by Escherichia coli O157 : H7 after oral inoculation." Journal of Medical Microbiology 54, no. 5 (May 1, 2005): 485–92. http://dx.doi.org/10.1099/jmm.0.45897-0.
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Enterohaemorrhagic Escherichia coli O157 : H7 infections of man have been associated with consumption of unpasteurized goat's milk and direct contact with kid goats on petting farms, yet little is known about colonization of goats with this organism. To assess the contribution of flagella and intimin of E. coli O157 : H7 in colonization of the goat, 8-week-old conventionally reared goats were inoculated orally in separate experiments with 1×1010 c.f.u. of a non-verotoxigenic strain of E. coli O157 : H7 (strain NCTC 12900 Nalr), an aflagellate derivative (DMB1) and an intimin-deficient derivative (DMB2). At 24 h after inoculation, the three E. coli O157 : H7 strains were shed at approximately 5×104 c.f.u. (g faeces)−1 from all animals. Significantly fewer intimin-deficient bacteria were shed only on days 2 (P = 0.003) and 4 (P = 0.014), whereas from day 7 to 29 there were no differences. Tissues from three animals inoculated with wild-type E. coli O157 : H7 strain NCTC 12900 Nalr were sampled at 24, 48 and 96 h after inoculation and the organism was cultured from the large intestine of all three animals and from the duodenum and ileum of the animal examined at 96 h. Tissues were examined histologically but attaching-effacing (AE) lesions were not observed at any intestinal site of the animals examined at 24 or 48 h. However, the animal examined at 96 h, which had uniquely shed approximately 1×107 E. coli O157 : H7 (g faeces)−1 for the preceding 3 days, showed a heavy, diffuse infection with cryptosporidia and abundant, multifocal AE lesions in the distal colon, rectum and at the recto-anal junction. These AE lesions were confirmed by immunohistochemistry to be associated with E. coli O157 : H7.
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Berresheim, H., C. Plass-Dülmer, T. Elste, N. Mihalopoulos, and F. Rohrer. "OH in the coastal boundary layer of Crete during MINOS: Measurements and relationship with ozone photolysis." Atmospheric Chemistry and Physics 3, no. 3 (June 5, 2003): 639–49. http://dx.doi.org/10.5194/acp-3-639-2003.
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Abstract. Hydroxyl radical (OH) concentrations were measured in August 2001 at Finokalia Station on the northeastern coast of Crete during the Mediterranean Intensive Oxidant Study (MINOS). OH was measured based on selected ion chemical ionization mass spectrometry (SI/CIMS) with a time resolution of 30 sec and signal integration of 5 min. The corresponding accuracy, precision, and detection limit were 20% (1σ), 11% (1σ), and 2.4 x 105 molecules cm-3 (2σ), respectively. OH levels showed a strong diurnal variability with high maxima (approximately 2 x 107 molecules cm-3) occurring around 13:30 LT (10:30 UTC) and nighttime values below the detection limit. Daily 24-hour average concentrations varied between 3.6-6.7 x 106 cm-3. For the total measurement period (6-21 August) the mean and standard deviation were 4.5 ± 1.1 x 106 cm-3. The OH data set is analyzed based on a classification into three periods: I: Aug 6-8, II: Aug 9-11, III: Aug 13-18. For each of the three periods the measured OH concentrations are described by the empirical function [OH] = a J(O1D)b, with J(O1D) being the ozone photolysis frequency and a = 1.4 x 1010 s cm-3, 1.7 x 1010 s cm-3, 2.2 x 1010 s cm-3, and b = 0.68, respectively. Taking into account the estimated precision of the OH measurements this empirical function using three values for a and one value for b explains 99% of the observed variance of OH. A detailed sensitivity analysis using a CH4-CO box model was performed to interpret this relationship, in particular the meanings of the pre-exponential factor a and the exponent b. It was found that the value of b which represents the total logarithmic dependence of [OH] on J(O1D) includes the individual contributions from the photolysis of O3, NO2, HCHO, HONO, and H2O2 which could be determined using the box model. For the conditions prevailing during the MINOS campaign the exponent b was found to be dominated by the contributions from O3- and NO2-photolysis. For the individual functional dependences between [OH] and J(O1D), [OH] and J(NO2), and J(NO2) and J(O1D) the partial logarithmic derivatives were determined to be 0.5, 0.6, and 0.3, respectively. Overall, the box model yields a value of 0.70 for the exponent b in very good agreement with the corresponding value derived from the empirical analysis of the measurements. This empirical approach in which the chemical air mass characteristics influencing the OH radical balance and thereby, the self-cleansing efficiency of the atmosphere, are represented by only two parameters which are constant over quite substantial time periods may be used in future experiments to test and compare OH measurements made in different atmospheric environments.
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Giewekemeyer, Klaus, Hugh T. Philipp, Robin N. Wilke, Andrew Aquila, Markus Osterhoff, Mark W. Tate, Katherine S. Shanks, et al. "High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector." Journal of Synchrotron Radiation 21, no. 5 (August 7, 2014): 1167–74. http://dx.doi.org/10.1107/s1600577514013411.
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Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 1088-keV photons pixel−1s−1, and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 1010 photons µm−2s−1within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while `still' images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described.
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Tanaka, Tsuyoshi, Yoriko Kokuryu, and Tadashi Matsunaga. "Novel Method for Selection of Antimicrobial Peptides from a Phage Display Library by Use of Bacterial Magnetic Particles." Applied and Environmental Microbiology 74, no. 24 (October 24, 2008): 7600–7606. http://dx.doi.org/10.1128/aem.00162-08.
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ABSTRACT Antimicrobial peptides were isolated from a phage display peptide library using bacterial magnetic particles (BacMPs) as a solid support. The BacMPs obtained from “Magnetospirillum magneticum” strain AMB-1 consist of pure magnetite (50 to 100 nm in size) and are covered with a lipid bilayer membrane derived from the invagination of the inner membrane. BacMPs are easily purified from a culture of magnetotactic bacteria by magnetic separation. Approximately 4 × 1010 PFU of the library phage (complexity, 2.7 × 109) was reacted with BacMPs. The elution of bound phages from BacMPs was performed by disrupting its membrane with phospholipase D treatment. Six candidate peptides, which were highly cationic and could bind onto the BacMP membrane, were obtained. They exhibited antimicrobial activity against Bacillus subtilis but not against Escherichia coli and Saccharomyces cerevisiae. The amino acid substitution of the selected peptide, KPQQHNRPLRHK (peptide 6-7), to enhance the hydrophobicity resulted in obvious antimicrobial activity against all test microorganisms. The present study shows for the first time that a magnetic selection of antimicrobial peptides from the phage display peptide library was successfully achieved by targeting the actual bacterial inner membrane. This BacMP-based method could be a promising approach for a high-throughput screening of antimicrobial peptides targeting a wide range of species.
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Tang, He, Jie Dong, Lan Zhang, and Wenke Sun. "Deformation of a spherical, viscoelastic, and incompressible Earth for a point load with periodic time change." Geophysical Journal International 222, no. 3 (June 1, 2020): 1909–22. http://dx.doi.org/10.1093/gji/ggaa268.
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SUMMARY Planetary-scale mass redistributions occur on Earth for certain spatiotemporal periods, and these surface mass changes excite the global periodic loading deformations of a viscoelastic Earth. However, the characteristics of periodic viscoelastic deformations have not been well investigated even in a simple earth model. In this study, we derive the semi-analytical Green's functions (fully analytical Love numbers) for long-standing point sources with given periods using a modified asymptotic scheme in a homogeneous Maxwell spherical earth model. Here, the asymptotic scheme is needed in order to obtain accurate semi-analytical time-dependent Green's functions. The amplitudes and phases of the Green's functions may be biased if only the series summations of the Love numbers are used because the influence of viscoelasticity is degree-dependent. We compare the viscoelastic and elastic periodic Green's functions with different material viscosities and loading periods and investigate the amplitude increase percentage and phase delay of the periodic displacement and geoid change. For example, our analysis revealed that the viscosity increases the amplitude by 40–120 per cent and delays the phase approximately −100° to 60° for the displacement and geoid change when bearing a 10-yr loading period, assuming a viscosity of 1018 Pa s and a shear modulus 4 × 1010 Pa.
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DeHart, Sarah L., Marc J. Heikens, and Schickwann Tsai. "Jagged2 promotes the development of natural killer cells and the establishment of functional natural killer cell lines." Blood 105, no. 9 (May 1, 2005): 3521–27. http://dx.doi.org/10.1182/blood-2004-11-4237.
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AbstractEmerging evidence indicates that Notch receptors and their ligands play important roles in the development of T cells and B cells. However, little is known about their possible roles in the development of other lymphoid cells. Here we demonstrate that Jagged2, a Notch ligand, stimulates the development of natural killer (NK) cells from Lin- Sca-1+ c-kit+ hematopoietic stem cells. Our culture system supports NK cell development for 2 to 3 months, often leading to the establishment of continuous NK cell lines. The prototype of such cell lines is designated as KIL. KIL depends on interleukin-7 for survival and proliferation and is NK1.1+ CD3- TCRαβ- TCRδγ- CD4- CD8- CD19- CD25+ CD43+ CD45+ CD49b- CD51+ CD94+ NKG2D+ Mac-1-/low B220- c-kit+ perforin I+ granzyme B+ Notch-1+, and cytotoxic. Like normal natural killer cells, the T-cell receptor-β loci of KIL remain in the germ-line configuration. In response to interleukin-2, KIL proliferates extensively (increasing cell number by approximately 1010-fold) and terminally differentiates into adherent, hypergranular NK cells. Our findings indicate that Jagged2 stimulates the development of natural killer cells and the KIL cell line preserves most properties of the normal NK precursors. As such, KIL provides a valuable model system for NK cell research.
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Lu, Shi-Jiang, Qiang Feng, Jennifer S. Park, Loyda Vida, Bao-Shiang Lee, Michael Strausbauch, Peter J. Wettstein, George R. Honig, and Robert Lanza. "Biologic properties and enucleation of red blood cells from human embryonic stem cells." Blood 112, no. 12 (December 1, 2008): 4475–84. http://dx.doi.org/10.1182/blood-2008-05-157198.
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Abstract Human erythropoiesis is a complex multistep process that involves the differentiation of early erythroid progenitors to mature erythrocytes. Here we show that it is feasible to differentiate and mature human embryonic stem cells (hESCs) into functional oxygen-carrying erythrocytes on a large scale (1010-1011 cells/6-well plate hESCs). We also show for the first time that the oxygen equilibrium curves of the hESC-derived cells are comparable with normal red blood cells and respond to changes in pH and 2,3-diphosphoglyerate. Although these cells mainly expressed fetal and embryonic globins, they also possessed the capacity to express the adult β-globin chain on further maturation in vitro. Polymerase chain reaction and globin chain specific immunofluorescent analysis showed that the cells increased expression of β-globin (from 0% to > 16%) after in vitro culture. Importantly, the cells underwent multiple maturation events, including a progressive decrease in size, increase in glycophorin A expression, and chromatin and nuclear condensation. This process resulted in extrusion of the pycnotic nuclei in up to more than 60% of the cells generating red blood cells with a diameter of approximately 6 to 8 μm. The results show that it is feasible to differentiate and mature hESCs into functional oxygen-carrying erythrocytes on a large scale.
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Goldstein, R. J., and R. J. Volino. "Onset and Development of Natural Convection Above a Suddenly Heated Horizontal Surface." Journal of Heat Transfer 117, no. 4 (November 1, 1995): 808–21. http://dx.doi.org/10.1115/1.2836296.
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The onset and development of flow in a thick horizontal layer subject to a near-constant flux heating from below has been studied experimentally. The overall heat-flux-based Rayleigh number, Ra*, ranges from 2 × 108 to 7 × 1010. Flow visualization shows the growth and breakdown of a conduction layer adjacent to the heated surface. Convection is characterized by the release of warm meandering plumes and thermals from a boundary layer. The planform of convection at the heated surface begins with a pattern of small spots suggestive of Be´nard cells. Some of these cells expand, forming a larger cell pattern. This continues until a quasi-steady state is reached in which the former cell boundaries form a slowly moving pattern of warm lines on the heated surface. The lines are believed to be the source of the plumes and thermals. Quantitatively, the onset of convection occurs at a constant (critical) Rayleigh number based on the conduction layer thickness, Raδ. Based on the first observation of fluid motion, this critical Rayleigh number is approximately 1300. Based on the heated surface temperature the critical Rayleigh number is 2700. The nondimensional wavenumber associated with the observed instabilities at the onset of convection is about 2.2.