A bioinspired bubble removal method in microchannels based on angiosperm xylem embolism repair

It is difficult to remove and eliminate bubbles in microchannels in many devices used in various biomedical fields, such as those needed for microfluidic immunoassays, point-of-care testing, and cell biology evaluations. Accumulated bubbles are associated with a number of negative outcomes, including a decrease in device sensitivity, inaccuracy of analysis results, and even functional failure. Xylem conduits of angiosperm have the ability to remove bubbles in obstructed conduits. Inspired by such an embolism repair mechanism, this paper proposes a bioinspired bubble removal method, which exhibits a prominent ability to dissolve bubbles continuously within a large range of flow rates (2 µL/min–850 µL/min) while retaining the stability and continuity of the flow without auxiliary equipment. Such a method also shows significant bubble removal stability in dealing with Newtonian liquids and non-Newtonian fluids, especially with high viscosity (6.76 Pa s) and low velocity (152 nL/min). Such advantages associated with the proposed bioinspired method reveal promising application prospects in macro/microfluidic fields ranging from 3D printing, implantable devices, virus detection, and biomedical fluid processing to microscale reactor operation and beyond

Towards prediction of ordered phases in rechargeable battery chemistry via group–subgroup transformation

Abstract: The electrochemical thermodynamic and kinetic characteristics of rechargeable batteries are critically influenced by the ordering of mobile ions in electrodes or solid electrolytes. However, because of the experimental difficulty of capturing the lighter migration ion coupled with the theoretical limitation of searching for ordered phases in a constrained cell, predicting stable ordered phases involving cell transformations or at extremely dilute concentrations remains challenging. Here, a group-subgroup transformation method based on lattice transformation and Wyckoff-position splitting is employed to predict the ordered ground states. We reproduce the previously reported Li0.75CoO2, Li0.8333CoO2, and Li0.8571CoO2 phases and report a new Li0.875CoO2 ground state. Taking the advantage of Wyckoff-position splitting in reducing the number of configurations, we identify the stablest Li0.0625C6 dilute phase in Li-ion intercalated graphite. We also resolve the Li/La/vacancy ordering in Li3xLa2/3−xTiO3 (0 < x < 0.167), which explains the observed Li-ion diffusion anisotropy. These findings provide important insight towards understanding the rechargeable battery chemistry

Diversity and aggregation patterns of plant species in a grass community

Abstract Both composition and aggregation patterns of species in a community are the outcome of community self-organizing. In this paper we conducted analysis on species diversity and aggregation patterns of plant species in a grass community, Zhuhai, China. According to the sampling survey, in total of 47 plant species, belonging to 16 families, were found. Compositae had 10 species (21.3%), seconded by Gramineae (9 species, 19.1%), Leguminosae (6 species, 12.8%), Cyperaceae (4 species, 8.5%), and Malvaceae (3 species, 6.4%). The results revealed that the means of aggregation indices I δ , I and m * /m were 21.71, 15.71 and 19.89 respectively and thus individuals of most of plant species strongly followed aggregative distribution. Iwao analysis indicated that both individuals of all species and clumps of all individuals of all species followed aggregative distribution. Taylor&apos;s power law indicated that individuals of all species followed aggregative distribution and aggregation intensity strengthened as the increase of mean density. We held that the strong aggregation intensity of a species has been resulted from the strong adaptation ability to the environment, the strong interspecific competition ability and the earlier establishment of the species. Fitting goodness of the mean, I, I δ , m * /m with probability distributions demonstrated that the mean (density), I, I δ , and m * /m over all species followed Weibull distribution rather than normal distribution. Lophatherum gracile, Paederia scandens (Lour.) Merr., Eleusine indica, and Alternanthera philoxeroides (Mart.) Griseb. were mostly aggregative, and Oxalis sp., Eleocharis plantagineiformis, Vernonia cinerea (L.) Less., and Sapium sebiferum (L.) Roxb, were mostly uniform in the spatial distribution. Importance values (IV) showed that Cynodon dactylon was the most important species, seconded by Desmodium triflorum (L.) DC., Cajanus scarabaeoides (L.) Benth., Paspalum scrobiculatum L., and Rhynchelytrum repens. Oxalis sp., Eleocharis plantagineiformis, and Vernonia cinerea (L.) Less. were the least important species in the community. Summed dominance ratio (SDR2) revealed that Cynodon dactylon and Desmodium triflorum (L.) DC. were the most dominant species in the community, followed by Rhynchelytrum repens, Paspalum scrobiculatum L., and Cajanus scarabaeoides (L.) Benth

Investigation of Particles and Gas Bubbles in Zr–0.8Sn–1Nb–0.3Fe Zr Alloys Irradiated by Krypton Ions

Two types of Zr&ndash;0.8Sn&ndash;1Nb&ndash;0.3Fe Zr alloys were irradiated by krypton ions in the temperature range from 320 to 400 &deg;C. The microstructure of the as-received alloys showed that the sizes of Zr crystals and (Zr, Nb)2Fe particles with face-centered cubic (FCC) structure increased from 3.9 &mu;m to 6.0 &mu;m and from 74.6 nm to 89.6 nm, respectively, after cold rolling and subsequent annealing. Kr+ irradiation-induced bubble formation in the Zr matrix was observed. The size of the gas bubbles increased with increasing ion fluence and irradiation temperature. An equation that related the bubble size, ion fluence, and temperature were established. Irradiation-induced amorphization of particles was observed and found to be related to the fabrication process and irradiation parameters. The particles in alloy #1 showed a higher irradiation tolerance than those in alloy #2. The threshold damage dose for the amorphization of particles in alloy #2 was 3.5 dpa at 320 &deg;C and 4.9 dpa at 360 &deg;C. The mechanisms for bubble growth and particle amorphization are also discussed

Investigation of mechanical properties and proton irradiation behaviors of SA-738 Gr.B steel used as reactor containment

The proton irradiation behaviors of two kinds of SA-738Gr.B steels prepared by different heat treatment used as AP1000 reactor containment were investigated by transmission electron microscopy and positron annihilation lifetime spectrum (PAS). The mechanical properties of as-received steels were also measured. In the unirradiated conditions, the SA-738Gr.B steels had high tensile strength and excellent impact fracture toughness, which met the performance requirements of ASME codes. Both kinds of SA-738Gr.B steels were irradiated by 400keV proton from 1.07×1017H+/cm2 to 5.37×1017H+/cm2 fluence at 150 ºC. Some voids and dislocation loops with several nanometers were observed in the cross-section irradiated samples prepared by electroplating and then twin-jet electropolishing technology. The number of irradiation defects increased with increasing of displacement damage, as well as for the mean positron lifetimes. The stress-relief annealing treatment improved irradiation resistance based on open volume defect analysis from proton irradiation. SA-738Gr.B (SR) steel had higher proton irradiation resistance ability than that of SA-738Gr.B (QT) steel. The mechanism of irradiation behaviors were also analyzed and discussed

Effect of Crystal Orientation on Self-Assembly Nanocones Formed on Tungsten Surface Induced by Helium Ion Irradiation and Annealing

The self-assembly nanocone structures on the surface of polycrystalline tungsten were created by He+ ion irradiation and then annealing, and the resulting topography and morphology were characterized using atomic force microscopy and scanning electron microscopy. The cross-sectional samples of the self-assembly nanocones were prepared using an in situ–focused ion beam and then observed using transmission electron microscopy. The self-assembly nanocones were induced by the combined effect of He+ ion irradiation, the annealing process and the chromium impurity. The distribution characteristics, density and morphology of the nanocones exhibited a distinct difference relating to the crystal orientations. The highest density of the nanocones was observed on the grain surface with a (1 1 1) orientation, with the opposite for that with a (0 0 1) orientation and a medium value on the (1 0 1)-oriented grain. The size of the self-assembly nanocones increased with increasing the annealing time which met a power-law relationship. Irradiation-induced defects acted as the nucleation locations of the protrusions which attracted the migration of the tiny amount of chromium atoms. Under the action of temperature, the protrusions finally evolved into the nanocones

Microstructure Analysis of Neutron Absorber Al/B4C Metal Matrix Composites

The microstructure of Al/B4C metal matrix composites (MMCs) used as neutron absorbers in both dry storage casks and wet storage pools of spent nuclear fuel was analyzed by SEM and TEM. A polishing method of a focused Ga+ ion beam was used to obtain an ideal sample surface with very low roughness, which was used to statistically analyze the distribution characteristics and size factor of B4C particles in the aluminum matrix. The area of B4C particles mainly ranged from 0 to 0.5 μm2, which was the proportion of 64.29%, 86.99% and 76.86% of total statistical results for the Al-15%B4C, Al-25%B4C and Al-30%B4C MMCs, respectively. The average area of B4C particles in the Al-15%B4C, Al-25%B4C and Al-30%B4C MMCs were about 1.396, 0.528 and 1.183 μm2, respectively. The nanoscale precipitates were analyzed by the element mappings in scanning transmission electron microscopy (STEM) mode and electron energy loss spectroscopy (EELS) mode, which included elliptic alloy precipitates with elemental Cu, Cr, Fe and Si, except for Al, and B4C nanoparticles with polygonal shape. The interface characteristics showed that the (021) crystal plane of B4C particle and (111) crystal plane of aluminum matrix grew together. The lattice misfit was about 1.68% for (111)Al//(021)B4C. The corrosion properties and corresponding mechanism of Al/B4C MMCs were investigated in an aqueous solution with 5000 ppm boric acid at 100 °C and atmospheric pressure, which showed that the mass increment rate was first decreased with increasing corrosion time and then increased

Microstructural Evolution of Dy2O3-TiO2 Powder Mixtures during Ball Milling and Post-Milled Annealing

The microstructural evolution of Dy2O3-TiO2 powder mixtures during ball milling and post-milled annealing was investigated using XRD, SEM, TEM, and DSC. At high ball-milling rotation speeds, the mixtures were fined, homogenized, nanocrystallized, and later completely amorphized, and the transformation of Dy2O3 from the cubic to the monoclinic crystal structure was observed. The amorphous transformation resulted from monoclinic Dy2O3, not from cubic Dy2O3. However, at low ball-milling rotation speeds, the mixtures were only fined and homogenized. An intermediate phase with a similar crystal structure to that of cubic Dy2TiO5 was detected in the amorphous mixtures annealed from 800 to 1000 °C, which was a metastable phase that transformed to orthorhombic Dy2TiO5 when the annealing temperature was above 1050 °C. However, at the same annealing temperatures, pyrochlore Dy2Ti2O7 initially formed and subsequently reacted with the remaining Dy2O3 to form orthorhombic Dy2TiO5 in the homogenous mixtures. The evolutionary mechanism of powder mixtures during ball milling and subsequent annealing was analyzed

Ion Irradiation-Induced Microstructural Evolution of Ni–Mo–Cr Low Alloy Steels

As leading candidates of sheet steels for advanced nuclear reactors, three types of Ni&#8315;Mo&#8315;Cr high-strength low alloy (HSLA) steels named as CNST1, CNST2 and CNSS3 were irradiated by 400 keV Fe+ with peak fluence to 1.4 &#215; 1014, 3.5 &#215; 1014 and 7.0 &#215; 1014 ions/cm2, respectively. The distribution and morphology of the defects induced by the sample preparation method and Fe+ irradiation dose were investigated by transmission electron microscopy (TEM) and positron-annihilation spectroscopy (PAS). TEM samples were prepared with two methods, i.e., a focused ion beam (FIB) technique and the electroplating and twin-jet electropolishing (ETE) method. Point defects and dislocation loops were observed in CNST1, CNST2 and CNSS3 samples prepared via FIB. On the other hand, samples prepared via the ETE method revealed that a smaller number of defects was observed in CNST1, CNST2 and almost no defects were observed in CNST3. It is indicated that artifact defects could be introduced by FIB preparation. The PAS S-W plots showed that the existence of two types of defects after ion implantation included small-scale defects such as vacancies, vacancy clusters, dislocation loops and large-sized defects. The S parameter of irradiated steels showed a clear saturation in PAS response with increasing Fe+ dose. At the same irradiation dose, higher values of the S-parameter were achieved in CNST1 and CNST2 samples when compared to that in CNSS3 samples. The mechanism and evolution behavior of irradiation-induced defects were analyzed and discussed