Multistep Dissociation of Fluorine Molecules under Extreme Compression.

All elements that form diatomic molecules, such as H_{2}, N_{2}, O_{2}, Cl_{2}, Br_{2}, and I_{2}, are destined to become atomic solids under sufficiently high pressure. However, as revealed by many experimental and theoretical studies, these elements show very different propensity and transition paths due to the balance of reduced volume, lone pair electrons, and interatomic bonds. The study of F under pressure can illuminate this intricate behavior since F, owing to its unique position on the periodic table, can be compared with H, with N and O, and also with other halogens. Nevertheless, F remains the only element whose solid structure evolution under pressure has not been thoroughly studied. Using a large-scale crystal structure search method based on first principles calculations, we find that, before reaching an atomic phase, F solid transforms first into a structure consisting of F_{2} molecules and F polymer chains and then into a structure consisting of F polymer chains and F atoms, a distinctive evolution with pressure that has not been seen in any other elements. Both intermediate structures are found to be metallic and become superconducting, a result that adds F to the elemental superconductors

Robotic Precisely Oocyte Blind Enucleation Method

Oocyte enucleation is a critical procedure for somatic cell nuclear transfer. Yet, the main steps of oocyte enucleation are still manually operated, which presents several drawbacks such as low precision, high repetition error, and long training time for operators. For improving the operation efficiency and success rate, a robotic precise oocyte blind enucleation method is presented in this paper. The proposed method involves the following key techniques: oocyte translation control, oocyte immobilization and penetration control, and enucleation volume control based on the adaptive slide mode. Compared with the manual blind enucleation method, the proposed robotic blind enucleation method reduced the operation time by 44.5% (manual method: 62 s vs. proposed method: 34.4 s), increased the accuracy of enucleation by 83.1% (manual method: 30.7 vs. proposed method: 5.2), increased the success rate from 80% to 93.3%, and increased the cleavage rate from 41.7% to 63.3%

Dielectric, piezoelectric, and ferroelectric properties of Al2O3 and MnO2 modified PbSnO3-PbTiO3- Pb(Mg1/3Nb2/3)O3 ternary ceramics

The PbSnO3-PbTiO3-Pb(Mg1/3Nb 2/3)O3 (PST-PMN) ternary system with morphotropic phase-boundary (MPB) compositions were fabricated using a two-step columbite precursor method. The effects of Al2O3 and MnO2 addition on the dielectric, piezoelectric, and ferroelectric properties of PST-PMN were investigated. MnO2 acted as an acceptor dopant and induced a hardening effect in PST-PMN, with decreased piezoelectric coefficients d33 and increased mechanical quality factors Q m, while the addition of Al2O3 led to the significant decrease of piezoelectric properties, attributed to the second phase. Of particular interest is the fact that the Mn-doped PST-PMN exhibited excellent properties when the doping level was in the range of 0.2-0.5 wt%, with piezoelectric d33, planar electromechanical coupling kp, dielectric permittivity Ïμr, Qm, remnant polarization Pr and coercive field EC being on the order of ∼510 pC N-1, ∼57%, 3120-3500, 530-600, 27-30 μC cm -2, and ∼8 kV cm-1, respectively, showing advantages over commercial PZT4-type ceramics, which are promising for high-power electromechanical applications. 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Fabrication of Cell-Laden Hydrogel Fibers with Controllable Diameters

Cell-laden hydrogel fibers are widely used as the fundamental building blocks to fabricate more complex functional three-dimensional (3D) structures that could mimic biological tissues. The control on the diameter of the hydrogel fibers is important so as to precisely construct structures in the above 3D bio-fabrication. In this paper, a pneumatic-actuated micro-extrusion system is developed to produce hydrogel fibers based on the crosslinking behavior of sodium alginate with calcium ions. Excellent uniformity has been obtained in the diameters of the fabricated hydrogel fibers as a proportional-integral-derivative (PID) control algorithm is applied on the driving pressure control. More importantly, a linear relationship has been obtained between the diameter of hydrogel fiber and the driving pressure. With the help of the identified linear model, we can precisely control the diameter of the hydrogel fiber via the control of the driving pressure. The differences between the measured and designed diameters are within ±2.5%. Finally, the influence of the calcium ions on the viability of the encapsulated cells is also investigated by immersing the cell-laden hydrogel fibers into the CaCl2 bath for different periods of time. LIVE/DEAD assays show that there is little difference among the cell viabilities in each sample. Therefore, the calcium ions utilized in the fabrication process have no impact on the cells encapsulated in the hydrogel fiber. Experimental results also show that the cell viability is 83 ± 2% for each sample after 24 h of culturing

Effect of Sn Content on the Phase Structure and Electrical Properties of PbSnO3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 Ternary Ceramics

PbSnO3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PSn-PMN-PT) ternary ceramics were successfully prepared by two-step columbite precursor method. The effects of Sn content on the phase structure and electrical properties of PSn-PMN-PT were investigated. X-ray powder diffraction (XRD) results indicated that all studied PSn-PMN-PT compositions located around the morphotropic phase boundary (MPB), with rhombohedral and tetragonal phases coexisted. With the decrease of Sn content, no change was observed in the XRD patterns of PSn-PMN-PT, while pyrochlore phase presented with excess Sn. The piezoelectric, dielectric and ferroelectric properties of PSn-PMN-PT were found to be improved with deficient Sn and deteriorate with increasing Sn content. In particular, the optimum piezoelectric and ferroelectric properties were achieved for PSn-PMN-PT ceramics with 0.2mol% deficient Sn, i.e. d(33)=similar to 530 pC/N, k(p)=similar to 56.4%, Q(m)=similar to 570, epsilon(r)=similar to 3070, tan delta=similar to 0.3%, P-r=similar to 28.9 mu C/cm(2) and E-c=similar to 8 kV/cm. Effect of Sn Content on the Phase Structure and Electrical.... Available from: https://www.researchgate.net/publication/273678929_Effect_of_Sn_Content_on_the_Phase_Structure_and_Electrical_Properties_of_PbSnO3-PbMg13Nb23O3-PbTiO3_Ternary_Ceramics [accessed Jun 15 2018]

Effect of Melatonin on the In Vitro Maturation of Porcine Oocytes, Development of Parthenogenetically Activated Embryos, and Expression of Genes Related to the Oocyte Developmental Capability

Melatonin treatment can improve quality and in vitro development of porcine oocytes, but the mechanism of improving quality and developmental competence is not fully understood. In this study, porcine cumulus–oocyte complexes were cultured in TCM199 medium with non-treated (control), 10−5 M luzindole (melatonin receptor antagonist), 10−5 M melatonin, and melatonin + luzindole during in vitro maturation, and parthenogenetically activated (PA) embryos were treated with nothing (control), or 10−5 M melatonin. Cumulus oophorus expansion, oocyte survival rate, first polar body extrusion rate, mitochondrial distribution, and intracellular levels of reactive oxygen species (ROS) and glutathione of oocytes, and cleavage rate and blastocyst rate of the PA embryos were assessed. In addition, expression of growth differentiation factor 9 (GDF9), tumor protein p53 (P53), BCL2 associated X protein (BAX), catalase (CAT), and bone morphogenetic protein 15 (BMP15) were analyzed by real-time quantitative PCR. The results revealed that melatonin treatment not only improved the first polar body extrusion rate and cumulus expansion of oocytes via melatonin receptors, but also enhanced the rates of cleavage and blastocyst formation of PA embryos. Additionally, melatonin treatment significantly increased intraooplasmic level of glutathione independently of melatonin receptors. Furthermore, melatonin supplementation not only significantly enhanced mitochondrial distribution and relative abundances of BMP15 and CAT mRNA, but also decreased intracellular level of ROS and relative abundances of P53 and BAX mRNA of the oocytes. In conclusion, melatonin enhanced the quality and in vitro development of porcine oocytes, which may be related to antioxidant and anti-apoptotic mechanisms

A Cell’s Viscoelasticity Measurement Method Based on the Spheroidization Process of Non-Spherical Shaped Cell

The mechanical properties of biological cells, especially the elastic modulus and viscosity of cells, have been identified to reflect cell viability and cell states. The existing measuring techniques need additional equipment or operation condition. This paper presents a cell’s viscoelasticity measurement method based on the spheroidization process of non-spherical shaped cell. The viscoelasticity of porcine fetal fibroblast was measured. Firstly, we introduced the process of recording the spheroidization process of porcine fetal fibroblast. Secondly, we built the viscoelastic model for simulating a cell’s spheroidization process. Then, we simulated the spheroidization process of porcine fetal fibroblast and got the simulated spheroidization process. By identifying the parameters in the viscoelastic model, we got the elasticity (500 Pa) and viscosity (10 Pa·s) of porcine fetal fibroblast. The results showed that the magnitude of the elasticity and viscosity were in agreement with those measured by traditional method. To verify the accuracy of the proposed method, we imitated the spheroidization process with silicone oil, a kind of viscous and uniform liquid with determined viscosity. We did the silicone oil’s spheroidization experiment and simulated this process. The simulation results also fitted the experimental results well

Robotic Micropipette Aspiration for Multiple Cells

As there are significant variations of cell elasticity among individual cells, measuring the elasticity of batch cells is required for obtaining statistical results of cell elasticity. At present, the micropipette aspiration (MA) technique is the most widely used cell elasticity measurement method. Due to a lack of effective cell storage and delivery methods, the existing manual and robotic MA methods are only capable of measuring a single cell at a time, making the MA of batch cells low efficiency. To address this problem, we developed a robotic MA system capable of storing multiple cells with a feeder micropipette (FM), picking up cells one-by-one to measure their elasticity with a measurement micropipette (MM). This system involved the following key techniques: Maximum permissible tilt angle of MM and FM determination, automated cell adhesion detection and cell adhesion break, and automated cell aspiration. The experimental results demonstrated that our system was able to continuously measure more than 20 cells with a manipulation speed quadrupled in comparison to existing methods. With the batch cell measurement ability, cell elasticity of pig ovum cultured in different environmental conditions was measured to find optimized culturing protocols for oocyte maturation

Difference in Energy Input and Output in Agricultural Production under Surface Irrigation and Water-Saving Irrigation: A Case Study of Kiwi Fruit in Shaanxi

China’s kiwi industry has seen rising production costs and shrinking planting areas in recent years; at the same time, the lack of professional production standards leads to the input redundancy and waste of production factors in the production process of kiwifruit, which intensifies the dilemma of unsustainable agricultural production. This has brought more and more serious challenges to the sustainable development of the industry. In order to solve this problem and clarify the composition and utilization efficiency of energy in the production process of kiwifruit, this study took Chinese kiwifruit production as the research object and analyzed the energy input and output under surface irrigation and water-saving irrigation from the perspective of energy. The results show that the energy input of kiwifruit production under traditional surface irrigation was 85.4 GJ/ha, and the energy output was 59.7 GJ/ha. Among all energy input elements, mineral fertilizers accounted for the highest proportion of energy input, accounting for 48.31%. Under water-saving irrigation, the energy input and output of kiwifruit production are 72.3 GJ/ha and 62.3 GJ/ha; the highest energy input is also mineral fertilizer. The data envelopment analysis results also confirmed that there is a large redundancy in the amount of mineral fertilizer. Compared with surface irrigation, water-saving irrigation technology has effectively improved the energy ratio (from 0.70 to 0.86), energy productivity (from 0.37 kg/MJ to 0.45 kg/MJ) as well as net energy (from −25.8 GJ/ha to −9.93 GJ/ha). Thus, promoting the application of water-saving irrigation technology and increasing the proportion of fertigation during the kiwi production process are necessary measures to promote the sustainable development of China’s kiwi industry

Difference in Energy Input and Output in Agricultural Production under Surface Irrigation and Water-Saving Irrigation: A Case Study of Kiwi Fruit in Shaanxi

China’s kiwi industry has seen rising production costs and shrinking planting areas in recent years; at the same time, the lack of professional production standards leads to the input redundancy and waste of production factors in the production process of kiwifruit, which intensifies the dilemma of unsustainable agricultural production. This has brought more and more serious challenges to the sustainable development of the industry. In order to solve this problem and clarify the composition and utilization efficiency of energy in the production process of kiwifruit, this study took Chinese kiwifruit production as the research object and analyzed the energy input and output under surface irrigation and water-saving irrigation from the perspective of energy. The results show that the energy input of kiwifruit production under traditional surface irrigation was 85.4 GJ/ha, and the energy output was 59.7 GJ/ha. Among all energy input elements, mineral fertilizers accounted for the highest proportion of energy input, accounting for 48.31%. Under water-saving irrigation, the energy input and output of kiwifruit production are 72.3 GJ/ha and 62.3 GJ/ha; the highest energy input is also mineral fertilizer. The data envelopment analysis results also confirmed that there is a large redundancy in the amount of mineral fertilizer. Compared with surface irrigation, water-saving irrigation technology has effectively improved the energy ratio (from 0.70 to 0.86), energy productivity (from 0.37 kg/MJ to 0.45 kg/MJ) as well as net energy (from −25.8 GJ/ha to −9.93 GJ/ha). Thus, promoting the application of water-saving irrigation technology and increasing the proportion of fertigation during the kiwi production process are necessary measures to promote the sustainable development of China’s kiwi industry