Continuous Rotation of Three Large Biomass Crops With High Bioconcentration Factor of Cadmium Can Effectively Repair Contaminated Farmlands

Traditional phytoremediation is one means for remediation of heavy metal pollution. For developing countries, the key factor in promoting the practical application of phytoremediation in polluted soils is selecting suitable plants tolerant to heavy metals and using these to produce products with economic value. A chicory-tobacco-peanut, three-season, rotation field experiment was carried on the utilization and remediation of cadmium (Cd) in contaminated farmlands. The results showed that all three crops had a strong capacity to accumulate Cd, with bioconcentration factors of chicory, tobacco, and peanut 6.61 to 11.97, 3.85 to 21.61, and 1.36 to 7, respectively. The yield of total dry biomass and phytoextraction efficiency for Cd reached 32.4 t ha-1 and 10.3% per year, respectively. The aboveground tissues of the three crops accounted for 83.9–91.2% of the total biomass in this rotation experiment. The content of peanut grain and oil met the National Food Safety Standard of China (0.5 mg kg-1, GB 2762-2017) and the Food Contaminant Limit of the European Union (0.1 mg kg-1, 18812006). Therefore, in addition to being used for phytoremediation in contaminated soils, this crop rotation system can also lead to economic benefits for local farmers.

The Effect of Temperature on Dynamic Characteristics of Frozen Clay under Principal Stress Rotation

The foundation soil is always subjected to complex stress, including continuous rotation of the principal stress caused by traffic and earthquake loads. To comprehend the dynamic characteristics of frozen clay under complex stress sate, including continuous rotation of the principal stress, this study investigates the effect of temperature on the dynamic characteristics of frozen clay under principal stress rotation using a frozen hollow cylinder apparatus (FHCA-300). The test results reveal that the cumulative plastic strain of frozen clay samples exponentially increases with the rising of temperature under principal stress rotation. The influence of temperature is more profound with a high cyclic stress ratio (CSR). A decrease in temperature can improve the stiffness of the frozen clay, reduces its energy dissipation, and enhances its ability to resist dynamic loading. However, the principal stress rotation phenomenon may aggravate the damage of frozen clay and increase the energy dissipation and reduces its ability to resist dynamic loading. Based on the experimental data, an empirical expression was proposed to describe the coupling influence of CSRs and temperature on the axial resilient modulus of frozen clay, which can predict the development of axial resilient modulus under different thermal-mechanical conditions.

Performance Evaluation of Self-Healable Torque Transmission Mechanism Using Phase Change of Low-Melting-Point-Metal and Application to Robot Joints

Self-healing properties of robots can aid in achieving a high level of motion continuity despite the absence of manual maintenance. Therefore, various studies have been conducted on self-healing materials and mechanisms to incorporate self-healing properties in robots. However, the self-healing performance of a motor rotation system, which is the power source of existing robots, has not been realized owing to the unsuitability of the self-healing method and material strength. Therefore, we propose a self-healable torque transmission mechanism using a low-melting-point metal that can be applied to transmission elements because of its strength and rigidity. Additionally, heating for self-healing can be performed without contact through induction heating. Hence, a self-healable torque transmission mechanism with a simple structure can be applied to a motor drive system where continuous rotation occurs. We evaluated the performance of the proposed mechanism experimentally by measuring the transmittable torque and the amount of energy absorbed when the torque transmission is interrupted. The results verify that the healing performance and energy absorption of the proposed mechanism remain stable, and the mechanism can heal without any performance degradation. Furthermore, the proposed mechanism was implemented in a robot to demonstrate its practical applications. It was found that this mechanism enables the robot to re-operate by self-repair even if it receives a load that can destroy the joint due to overload, and the robot's ability to continue motion could thus be improved.

Evaluation of Curved Canal Transportation Using the Neoniti Rotary System with Reciprocal Motion: A Comparative Study

The ideal root canal preparation is where the original canal morphology is maintained during the biomechanical preparation. Preparation of curved canals has always been a challenge to clinicians. Better results have been suggested for a single NiTi instrument with reciprocating motion than the conventional continuous rotation method in the preparation of curved root canals. Although the Neoniti rotary system is not suggested to be used with reciprocal motion, running a pilot study, we found that it could be possible. The present study aimed to investigate if shaping curved canals using the Neoniti rotary system with reciprocal motion leads to better results in terms of root canal transportation. One hundred acrylic j-shape canal simulator endoblocks were used in this study. Five preparation sequences were applied: GPS followed by A1#20 (GPS + A1#20), GPS followed by A1#20 and then A1#25 (GPS + A1#20 + A1#25), GPS followed by A1#25 (GPS + A1#25), hand file followed by A1#20 (hand file + A1#20), and GPS followed by A1#20 (with reciprocal motion) (GPS + A1#20(reciprocal)). Pictures were taken from blocks once before and once after preparation from two dimensions. Before-and-after pictures were superimposed in Photoshop software. Measurements were performed in Digimizer. The number of autoreverses and pecking motions was recorded after reviewing the recorded videos. Data were analyzed in SPSS, version 26. A p value of less than 0.05 was considered statistically significant. The group GPS + A1#20 + A1#25 had more transportation compared with the others, at apical, middle, and coronal thirds not only in the frontal view but also in the lateral view. Other groups were not significantly different. The number of peckings and autoreverses was significantly less when A1#25 was used after GPS and A1#20. When A1#20 was used with reciprocal motion, it had less peckings compared with the same file with continuous rotation, and no autoreverses were observed in that group. Using Neoniti files with reciprocal motion might result in less instrument fatigue and favorable results, with respect to canal anatomy preservation. Using A1#20 before A1#25 also will decrease the stress on the instrument during preparation. However, this may lead to significantly more canal transportation.

Chirality and accurate structure models by exploiting dynamical effects in continuous-rotation 3D ED data

Dynamical diffraction effects are usually considered a nuisance for structure analysis from continuous-rotation 3D electron diffraction (3D ED) data like cRED and MicroED. Here we demonstrate that by accounting for these effects during the structure refinement, significantly improved models can be obtained in terms of accuracy and reliability with up to four-fold reduction of the noise level in difference Fourier maps in comparison to the standard structure determination routines that ignore dynamical diffraction. As dynamical diffraction effects break the inversion symmetry of the diffraction, they allow a quick, easy, and reliable determination of the absolute structure of chiral crystals.

Bearing life calculations in rotating and oscillating applications

This paper begins by describing standard bearing life models in continuous rotation before going on to explain how the bearing life can be calculated for roller and ball bearings in oscillatory applications. An oscillation factor a_osc is introduced which accounts for the oscillating and stationary ring. This can be calculated numerically as a function of the oscillation angle θ and load zone parameter ε as well the parameters γ =D·cos(a)/dm and the ball-race osculation factors. Critical angles as used by Rumbarger are also employed at low θ values. Appropriate curve-fitted relationships for both roller and ball bearings are then given for a simple calculation of aosc with an accuracy of approximately 10%. Finally, several methods are suggested for estimating the ε parameter using a real case with a Finite Element Analysis load distribution accounting for structural ring deformation and ball-race contact angle variations. The results derived in this paper allow the lifetime of any arbitrary oscillating ball or roller bearing to be calculated.

Ab initio phasing macromolecular structures using electron-counted MicroED data

Structures of two globular proteins were determined ab initio using microcrystal electron diffraction (MicroED) data that was collected on a direct electron detector in counting mode. Microcrystals were identified using a scanning electron microscope (SEM) and thinned with a focused ion-beam (FIB) to produce crystalline lamellae of ideal thickness. Continuous rotation data were collected using an ultra-low exposure rate on a Falcon 4 direct electron detector in electron-counting mode. For the first sample, triclinic lysozyme extending to 0.87 A resolution, an ideal helical fragment of only three alanine residues provided initial phases. These phases were improved using density modification, allowing the entire atomic structure to be built automatically. A similar approach was successful on a second macromolecular sample, proteinase K, which is much larger and diffracted to a modest 1.5 A resolution. These results demonstrate that macromolecules can be determined to sub-Angstrom resolution by MicroED and that ab initio phasing can be successfully applied to counting data collected on a direct electron detector.

Population dynamics of the thalamic head direction system during drift and reorientation

The head direction (HD) system is classically modeled as a ring attractor network1,2 which ensures a stable representation of the animal’s head direction. This unidimensional description popularized the view of the HD system as the brain’s internal compass3,4. However, unlike a globally consistent magnetic compass, the orientation of the HD system is dynamic, depends on local cues and exhibits remapping across familiar environments5. Such a system requires mechanisms to remember and align to familiar landmarks, which may not be well described within the classic 1-dimensional framework. To search for these mechanisms, we performed large population recordings of mouse thalamic HD cells using calcium imaging, during controlled manipulations of a visual landmark in a familiar environment. First, we find that realignment of the system was associated with a continuous rotation of the HD network representation. The speed and angular distance of this rotation was predicted by a 2nd dimension to the ring attractor which we refer to as network gain, i.e. the instantaneous population firing rate. Moreover, the 360-degree azimuthal profile of network gain, during darkness, maintained a ‘memory trace’ of a previously displayed visual landmark. In a 2nd experiment, brief presentations of a rotated landmark revealed an attraction of the network back to its initial orientation, suggesting a time-dependent mechanism underlying the formation of these network gain memory traces. Finally, in a 3rd experiment, continuous rotation of a visual landmark induced a similar rotation of the HD representation which persisted following removal of the landmark, demonstrating that HD network orientation is subject to experience-dependent recalibration. Together, these results provide new mechanistic insights into how the neural compass flexibly adapts to environmental cues to maintain a reliable representation of the head direction.

Aerodynamics of inclined cylindrical bodies free-flying in a hypersonic flowfield

The influence of the flight attitude on aerodynamic coefficients and static stability of cylindrical bodies in hypersonic flows is of interest in understanding the re/entry of space debris, meteoroid fragments, launch-vehicle stages and other rotating objects. Experiments were therefore carried out in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. A free-flight technique was employed in H2K, which enables a continuous rotation of the cylinder without any sting interferences in a broad angular range from 0$$^{\circ }$$ ∘ to 90$$^{\circ }$$ ∘ . A high-speed stereo-tracking technique measured the model motion during free-flight and high-speed schlieren provided documentation of the flow topology. Aerodynamic coefficients were determined in careful post-processing, based on the measured 6-degrees-of-freedom (6DoF) motion data. Numerical simulations by NASA’s flow solvers Cart3D and US3D were performed for comparison purposes. As a result, the experimental and numerical data show a good agreement. The inclination of the cylinder strongly effects both the flowfield and aerodynamic loads. Experiments and simulations with concave cylinders showed marked difference in aerodynamic behavior due to the presence of a shock–shock interaction (SSI) near the middle of the model. Graphic abstract

Amorphous topological phases protected by continuous rotation symmetry

Protection of topological surface states by reflection symmetry breaks down when the boundary of the sample is misaligned with one of the high symmetry planes of the crystal. We demonstrate that this limitation is removed in amorphous topological materials, where the Hamiltonian is invariant on average under reflection over any axis due to continuous rotation symmetry. We show that the edge remains protected from localization in the topological phase, and the local disorder caused by the amorphous structure results in critical scaling of the transport in the system. In order to classify such phases we perform a systematic search over all the possible symmetry classes in two dimensions and construct the example models realizing each of the proposed topological phases. Finally, we compute the topological invariant of these phases as an integral along a meridian of the spherical Brillouin zone of an amorphous Hamiltonian.