Structural and mechanical stability of the nano-crystalline Ni–Ti (50.9 at.% Ni) shape memory alloy during short-term heat treatments

In this study, the nano-crystalline Nitinol (50.9 at.% Ni) was prepared by 40% cold deformation. Subsequently it was subjected to 15-min-heat treatments at 300–550 °C. Changes of the structure and mechanical properties were studied by transmission electron microscopy, micro X-ray diffraction, differential scanning calorimetry, Vickers hardness measurements, tensile and bend-type fatigue testing. It was shown that the cold drawn material contains textured nano-crystalline B2 grains of 50 nm in thickness and a high concentration of lattice defects. Its tensile strength, hardness and fatigue life were 1521 MPa, 421 HV0.05 and 2435 bending cycles to fracture, respectively. After heat-treatment up to 450 °C/15 min the material underwent Ni₄Ti₃ precipitation and partial recovery processes. Heat-treatments at above 450 °C induced recrystallization, grain and precipitate growth. Hardness and fatigue lives showed maxima of 692 HV0.05 and 5883 cycles, respectively, after heat-treatments at 450 °C/15 min. In contrast, both tensile strength and B2 → B19′ transformation stress decreased with increasing heat-treatment temperature, but a decrease of the tensile strength after heat-treatments at 300–450 °C was slow (tensile strength after heat-treatment at 450 °C/15 min was 1486 MPa). The observed variations of mechanical characteristics were discussed in relation to structural changes observed.     

干制麻辣鸡肉丝研制

以开发旅游休闲小食品干制麻辣鸡肉丝为目标,对干制鸡肉丝生产工艺进行研究,通过感官评分,确定其最佳生产工艺。研究结果表明:鸡肉丝的大小以切成3~4cm×0.5cm×0.5cm左右的细丝较为适宜;其工艺条件以先切丝后卤制再炒制烘烤为佳;卤制条件为先大火30~40min后小火1~2h,炒制烘烤条件为炒制15min左右,然后在50~60℃烘烤1~3h。     

铠装硅酸钾胶黏剂在特殊工况下的绝缘失效分析

为探索铠装硅酸盐胶黏剂在特殊环境下的绝缘特性，本文制备不同碱金属离子含量及固液配比的硅酸钾胶黏剂样品，将其固封于不锈钢管体中，在潮湿环境与高温条件下分析其绝缘性能并进行失效分析。结果表明：在潮湿环境中，胶体中的固液配比及碱金属（K⁺）含量会影响铠装试样的整体绝缘性能，当固液配比为2∶1时，硅酸钾与硅溶胶质量比在（2～1）∶1之间时，其绝缘效果较佳；在高温条件下，随着温度的升高及保温时间的延长，铠装壳体中部分合金元素渗入胶体表面，造成样品绝缘性能较大幅度的下降。     

Experimental study on the load bearing behavior of geosynthetic reinforced soil bridge abutments with different facing conditions

This paper presents an experimental study on reduced-scale model tests of geosynthetic reinforced soil (GRS) bridge abutments with modular block facing, full-height panel facing, and geosynthetic wrapped facing to investigate the influence of facing conditions on the load bearing behavior. The GRS abutment models were constructed using sand backfill and geogrid reinforcement. Test results indicate that footing settlements and facing displacements under the same applied vertical stress generally increase from full-height panel facing abutment, to modular block facing abutment, to geosynthetic wrapped facing abutment. Measured incremental vertical and lateral soil stresses for the two GRS abutments with flexible facing are generally similar, while the GRS abutment with rigid facing has larger stresses. For the GRS abutments with flexible facing, maximum reinforcement tensile strain in each layer typically occurs under the footing for the upper reinforcement layers and near the facing connections for the lower layers. For the full-height panel facing abutment, maximum reinforcement tensile strains generally occur near the facing connections.     

Persistence of lower dimensional invariant tori in a class of reversible systems

In this paper we prove the persistence of lower dimensional invariant tori for a class of reversible systems without any non-degeneracy condition. In the proof, we use the special nature that the dimension of the frequency ω is 2 and the modified KAM iteration to prove the persistence of lower dimensional hyperbolic invariant tori, but the frequency has some small shifts from small perturbations.     

In-vitro and in-vivo comparison of T-OA microemulsions and solid dispersions based on EPDC

The goal of this study was to enhance the absorption of a new water-insoluble antitumor lead compound, T-OA (3β-hydroxyolea-12-en-28-oic acid-3, 5, 6-trimethylpyrazin-2-methyl ester). Early-stage preparation discovery concept (EPDC) was employed in this study. Based on this concept, a microemulsion system was chosen as the method of improving bioavailability. The solubility of T-OA was checked in different oils, surfactants and cosurfactants. Ternary phase diagrams were constructed to evaluate the microemulsion domain. Developed high-performance liquid chromatography method was used to determine drug content. The transparent o/w microemulsion formulation composed of oleic acid (oil), Tween 80 (surfactant), ethanol (co-surfactant) and water enhanced the solubility of T-OA up to 20?mg/mL. It was characterized in terms of appearance, content, viscosity, zeta potential, conductivity, morphology and particle size. The particle size distribution, viscosity, conductivity and zeta potential were found to be 70?nm, 15.57?MPa?s, 44.1?μS?cm^?1 and ?0.174, respectively. Oral bioavailability of T-OA microemulsion and oleic acid solution were checked by using rat model. Contrast to the solid dispersion and proto drug, the area-under-the-curve (AUC) of T-OA microemulsion and oleic acid solution were significantly enhanced. The relative bioavailability of T-OA microemulsion was found to be 5654.7%, which is 57-fold higher than the pure drug. Improved T-OA solubility in microemulsion was found sustained 48?h in dilution study. While the solid dispersion may precipitate under the gastrointestinal circumstance based on dilution results. The in-vivo and in-vitro results indicated that, compare to improve the solubility, it is more important to maintain and prolong the T-OA dissolved status, for improvement of the in-vivo absorption.     

Influence of carbonation on the low-temperature consolidation by Spark Plasma Sintering of carbonated calcium phosphate bioceramics

Calcium phosphates (CaP) such as biomimetic nanocrystalline apatite or amorphous calcium phosphate are hydrated bioactive compounds particularly suitable for bone repair applications due to their similarity with bone mineral. However, their consolidation in ceramic parts deserves special attention as they are thermodynamically metastable and can decompose into less bioactive phases upon heating. Adapted strategies are needed to obtain bulk bioceramics. Spark Plasma Sintering (SPS) has been shown to allow cold sintering of such compounds at temperatures like 150 °C while preserving the hydrated character and nanosized dimensions of the precursor powders. To this date, however, the role of the degree of carbonation of these precursors on the densification of CO₃-bearing CaP compounds via SPS has not been explored despite the natural carbonation of bone. In this work, several carbonated CaP hydrated compounds were prepared and consolidated by SPS and the characteristics of the obtained ceramics was scrutinized with respect to the starting powders. Two carbonation routes were carried out: via volume carbonation during powder synthesis or via subsequent surface ion exchange. All samples tested led to apatitic compounds after SPS, including amorphous CaP. We show that the degree of carbonation negatively affects the densification rate and propose possible hypotheses explaining this behavior. Evolution in the nature of the carbonate sites (apatitic A-, B-types and labile surface carbonates) before and after SPS is also noticed and commented. The consolidation of such compounds is however proven possible, and gives rise to bone-like apatitic compounds with great potential as bioactive resorbable ceramics for bone regeneration.     

Automatic monitoring system for individual dairy cows based on a deep learning framework that provides identification via body parts and estimation of body condition score

Body condition score (BCS) is a common tool for indirectly estimating the mobilization of energy reserves in the fat and muscle of cattle that meets the requirements of animal welfare and precision livestock farming for the effective monitoring of individual animals. However, previous studies on automatic BCS systems have used manual scoring for data collection, and traditional image extraction methods have limited model performance accuracy. In addition, the radio frequency identification device system commonly used in ranching has the disadvantages of misreadings and damage to bovine bodies. Therefore, the aim of this research was to develop and validate an automatic system for identifying individuals and assessing BCS using a deep learning framework. This work developed a linear regression model of BCS using ultrasound backfat thickness to determine BCS for training sets and tested a system based on convolutional neural networks with 3 channels, including depth, gray, and phase congruency, to analyze the back images of 686 cows. After we performed an analysis of image model performance, online verification was used to evaluate the accuracy and precision of the system. The results showed that the selected linear regression model had a high coefficient of determination value (0.976), and the correlation coefficient between manual BCS and ultrasonic BCS was 0.94. Although the overall accuracy of the BCS estimations was high (0.45, 0.77, and 0.98 within 0, 0.25, and 0.5 unit, respectively), the validation for actual BCS ranging from 3.25 to 3.5 was weak (the F1 scores were only 0.6 and 0.57, respectively, within the 0.25-unit range). Overall, individual identification and BCS assessment performed well in the online measurement, with accuracies of 0.937 and 0.409, respectively. A system for individual identification and BCS assessment was developed, and a convolutional neural network using depth, gray, and phase congruency channels to interpret image features exhibited advantages for monitoring thin cows.     

涂层工艺及参数对巧克力制品品质的影响

通过单因素和正交试验,研究了巧克力涂层温度、涂层厚度和冷却条件对巧克力涂层产品品质的影响。结果表明:巧克力冷却条件是影响巧克力涂层产品品质的首要因素,其次是涂层温度和涂层厚度。优化后最终成品巧克力涂层工艺参数是:36℃的涂层温度、0.5 mm的涂层厚度和12℃-10℃-12℃的冷却条件。     

Investigation on the pinch point position in heat exchangers

The pinch point is important for analyzing heat transfer in thermodynamic cycles.With the aim to reveal the importance of determining the accurate pinch point,the research on the pinch point position is carried out by theoretical method.The results show that the pinch point position depends on the parameters of the heat transfer fluids and the major fluid properties.In most cases,the pinch point locates at the bubble point for the evaporator and the dew point for the condenser.However,the pinch point shifts to the supercooled liquid state in the near critical conditions for the evaporator.Similarly,it shifts to the superheated vapor state with the condensing temperature approaching the critical temperature for the condenser.It even can shift to the working fluid entrance of the evaporator or the supercritical heater when the heat source fluid temperature is very high compared with the absorbing heat temperature.A wrong position for the pinch point may generate serious mistake.In brief,the pinch point should be founded by the iterative method in all conditions rather than taking for granted.