Sea Ice Detection Based on Differential Delay-Doppler Maps from UK TechDemoSat-1

Global Navigation Satellite System (GNSS) signals can be exploited to remotely sense atmosphere and land and ocean surface to retrieve a range of geophysical parameters. This paper proposes two new methods, termed as power-summation of differential Delay-Doppler Maps (PS-D) and pixel-number of differential Delay-Doppler Maps (PN-D), to distinguish between sea ice and sea water using differential Delay-Doppler Maps (dDDMs). PS-D and PN-D make use of power-summation and pixel-number of dDDMs, respectively, to measure the degree of difference between two DDMs so as to determine the transition state (water-water, water-ice, ice-ice and ice-water) and hence ice and water are detected. Moreover, an adaptive incoherent averaging of DDMs is employed to improve the computational efficiency. A large number of DDMs recorded by UK TechDemoSat-1 (TDS-1) over the Arctic region are used to test the proposed sea ice detection methods. Through evaluating against ground-truth measurements from the Ocean Sea Ice SAF, the proposed PS-D and PN-D methods achieve a probability of detection of 99.72% and 99.69% respectively, while the probability of false detection is 0.28% and 0.31% respectively

Black Phosphorus Q-Switched Large-Mode-Area Tm-Doped Fiber Laser

We report on a passively Q-switched fiber laser with black phosphorus as saturable absorber. By employing the sol-gel fabricated large-mode-area Tm-doped fiber as gain medium, a high-energy Q-switched fiber laser has been demonstrated which delivers the maximum pulse energy of 11.72 μJ with the pulse width of 660 ns at the wavelength of 1954 nm. Our experimental results indicate that BP Q-switched large-mode-area Tm-doped fiber laser is an effective and reliable approach to generate high-energy pulses at 2 μm

Comparison of genetic impact on growth and wood traits between seedlings and clones from the same plus trees of Pinus koraiensis

To evaluate the relationships among clones and open pollinated families from the same plus trees and to select elite breeding materials, growth, and wood characteristics of 33-year-old Pinus koraiensis clones and families were measured and analyzed. The results show that growth and wood characters varied significantly. The variation due to clonal effects was higher than that of family effects. The ratio of genetic to phenotypic coefficient of variation of clones in growth and wood traits was above 90%, and the repeatability of these characteristics was more than 0.8, whereas the ratio of genetic to phenotypic coefficient of variation of families was above 90%. The broad-sense heritability of all characteristics exceeded 0.4, and the narrow-sense family heritability of growth traits was less than 0.3. Growth characteristics were positively correlated with each other, but most wood properties were weakly correlated in both clones and families. Fiber length and width were positively correlated between clones and families. Using the membership function method, eleven clones and four families were selected as superior material for improved diameter growth and wood production, and two families from clonal and open-pollinated trees showed consistently better performance. Generally, selection of the best clones is an effective alternative to deployment of families as the repeatability estimates from clonal trees were higher than narrow-sense heritability estimates from open pollinated families. The results provide valuable insight for improving P. koraiensis breeding programs and subsequent genetic improvement

DNp73 improves generation efficiency of human induced pluripotent stem cells

<p>Abstract</p> <p>Background</p> <p>Recent studies have found that p53 and its' associated cell cycle pathways are major inhibitors of human induced pluripotent stem (iPS) cell generation. In the same family as p53 is p73, which shares sequence similarities with p53. However, p73 also has distinct properties of its own, such as two alternative promoters to express transactivation of p73 (TAp73) and N terminal deleted p73 (DNp73). Functionally, TAp73 acts similarly to p53 in tumor suppression. However, DNp73, on the other hand acts as an oncogene to suppress p53 and p73 induced apoptosis. Therefore, how can p73 have opposing roles in human iPS cell generation?</p> <p>Results</p> <p>Transcription factors, Oct4, Sox2, Klf4 and cMyc (4TF, Yamanaka factors) are used as basal conditions to generate iPS cells. In addition, the factor of DNp73(actually alpha splicing DNp73, DNp73α) is used to generate iPS cells. The experiment found that the addition of DNp73 gene increases human iPS cell generation efficiency by 12.6 folds in comparison to human fibroblast cells transduced with only the basal conditions. Also, iPS cells generated with DNp73 expression are more resistant to <it>in vitro </it>and <it>in vivo </it>differentiation.</p> <p>Conclusions</p> <p>This study found DNp73, a family member of p53, is also involved in the human iPS cell generation. Specifically, that the involvement of DNp73 generates iPS cells that are more resistant to <it>in vitro </it>and <it>in vivo </it>differentiation. Therefore, this data may prove to be useful in future developmental studies and cancer researches.</p

Sea Ice Detection Based on Differential Delay-Doppler Maps from UK TechDemoSat-1

Global Navigation Satellite System (GNSS) signals can be exploited to remotely sense atmosphere and land and ocean surface to retrieve a range of geophysical parameters. This paper proposes two new methods, termed as power-summation of differential Delay-Doppler Maps (PS-D) and pixel-number of differential Delay-Doppler Maps (PN-D), to distinguish between sea ice and sea water using differential Delay-Doppler Maps (dDDMs). PS-D and PN-D make use of power-summation and pixel-number of dDDMs, respectively, to measure the degree of difference between two DDMs so as to determine the transition state (water-water, water-ice, ice-ice and ice-water) and hence ice and water are detected. Moreover, an adaptive incoherent averaging of DDMs is employed to improve the computational efficiency. A large number of DDMs recorded by UK TechDemoSat-1 (TDS-1) over the Arctic region are used to test the proposed sea ice detection methods. Through evaluating against ground-truth measurements from the Ocean Sea Ice SAF, the proposed PS-D and PN-D methods achieve a probability of detection of 99.72% and 99.69% respectively, while the probability of false detection is 0.28% and 0.31% respectively

Probing the Soft and Nanoductile Mechanical Nature of Single and Polycrystalline Organic–Inorganic Hybrid Perovskites for Flexible Functional Devices

Although organic–inorganic hybrid perovskites have been extensively investigated for promising applications in energy-related devices, their mechanical properties, which restrict their practical deployment as flexible and wearable devices, have been largely unexplored at the atomistic level. Toward this level of understanding, we predict the elastic constant matrix and various elastic properties of CH₃NH₃PbI₃ (MAPbI₃) using atomistic simulations. We find that single-crystalline MAPbI₃ is much stiffer and exhibits higher ultimate tensile strength than polycrystalline samples, but the latter exhibit unexpected, greatly enhanced nanoductility and fracture toughness, resulting from the extensive amorphization during the yielding process. More interestingly, polycrystalline MAPbI₃ exhibits inverse Hall–Petch grain-boundary strengthening effect, in which the yield stress is reduced when decreasing the grain size, due to amorphous grain boundaries. By monitoring the centro-symmetry parameter and local stress evolution, we confirm the soft and nanoductile nature of defective MAPbI₃ with a crack. By conducting atomic stress decomposition, we attribute such fracture toughness primarily to the strong electrostatic interactions between the ionic components. The observed limited brittle fracture behavior is attributed to the transformation of partial edge dislocations to disordered atoms (nanovoid formation). A significant plastic deformation region is observed when nanovoids enlarge and coalesce with adjacent ones, which ultimately leads to crack propagations <i>via</i> ionic-chain breaking. After comparing with traditional inorganic energy-related materials, we find that hybrid perovskites are more compressible and can absorb more strain energy before fracture, which makes them well suited for wearable functional devices with high mechanical flexibility and robustness

Effects of Ferulic Acid Esterase-Producing Lactic Acid Bacteria and Storage Temperature on the Fermentation Quality, In Vitro Digestibility and Phenolic Acid Extraction Yields of Sorghum (Sorghum bicolor L.) Silage

Two lactic acid bacteria (LAB) strains with different ferulic acid esterase (FAE) activities were isolated: Lactobacillus farciminis (LF18) and Lactobacillus plantarum (LP23). The effects of these strains on the fermentation quality, in vitro digestibility and phenolic acid extraction yields of sorghum (Sorghum bicolor L.) silage were studied at 20, 30 and 40 &deg;C. Sorghum was ensiled with no additive (control), LF18 or LP23 for 45 days. At 40 &deg;C, the lactic acid content decreased, whereas the ammonia nitrogen (NH3-N) content significantly increased (p &lt; 0.05). At all three temperatures, the inoculants significantly improved the lactic acid contents and reduced the NH3-N contents (p &lt; 0.05). Neither LP23 nor LF18 significantly improved the digestibility of sorghum silages (p &gt; 0.05). The LP23 group exhibited higher phenolic acid extraction yields at 30 &deg;C (p &lt; 0.05), and the corresponding yields of the LF18 and control groups were improved at 40 &deg;C (p &lt; 0.05). FAE-producing LABs might partially ameliorate the negative effects of high temperature and improve the fermentation quality of sorghum silage. The screened FAE-producing LABs could be candidate strains for preserving sorghum silage at high temperature, and some further insights into the relationship between FAE-producing LABs and ensiling temperatures were obtained

Lithiation-Assisted Strengthening Effect and Reactive Flow in Bulk and Nanoconfined Sulfur Cathodes of Lithium–Sulfur Batteries

Lithiation of electrode materials can lead to significant microstructural evolution and changes in their mechanical behaviors in lithium batteries. Lithium–sulfur (Li–S) batteries have recently attracted extensive attention, where carbon matrices have been utilized to retain S content by restricting the dissolution of polysulfide into electrolytes. Here we systematically investigate S cathode upon unconfined and nanoconfined lithiation using reactive molecular dynamics simulations. We demonstrate the great ductility of lithiated amorphous S cathode (a-Li_<i>x</i>S) governed by overcoordination sites, as well as the resulting strengthening effect of a-Li_<i>x</i>S due to the formation of stronger Li–S bonds upon lithiation. Fracture and cavitation studies also indicate the dominant role of shear banding, which is facilitated by overcoordinated S “plastic carriers”, in accommodating the plastic deformation of a-Li_<i>x</i>S under tensile loading. Based on a chemo-mechanical yield function, we confirm two-dimensionally nanoconfined lithiation reaction can facilitate the out-of-plane inelastic deformation (“reactive flow”) of a-Li_<i>x</i>S at a much lower level of biaxial stress. The atomistic understanding of lithiation behaviors of S cathodes provides fundamental insight into the optimal design of carbon-based S composite cathode with outstanding mechanical integrity, as well as the prediction of lithiation behavior of other electrode materials, such as silicon, metal oxides, and graphite