Theoretical analysis and modelling of degradation for III–V lasers on Si

Abstract: InAs/GaAs quantum-dot (QD) lasers offer a promising method to realise Si-based on-chip light sources. However, the monolithic integration of III–V materials on Si introduces a high density of threading dislocations (TDs), which limits the performance of such a laser device in terms of device lifetime. Here, we proposed a kinetic model including a degradation term and a saturation term to simulate the degradation process caused by the TDs in the early stage of laser operation. By using a rate equation model, the current density in the wetting layer, where the TDs concentrate, is calculated. We compared the rate of degradation of QD lasers with different cavity lengths and of quantum-well lasers, where both are directly grown on Si substrates, by varying the fitting parameters in the calculation of current densities in the kinetic model

Is Continuous Heart Rate Monitoring of Livestock a Dream or Is It Realistic? A Review

For all homoeothermic living organisms, heart rate (HR) is a core variable to control the metabolic energy production in the body, which is crucial to realize essential bodily functions. Consequently, HR monitoring is becoming increasingly important in research of farm animals, not only for production efficiency, but also for animal welfare. Real-time HR monitoring for humans has become feasible though there are still shortcomings for continuously accurate measuring. This paper is an effort to estimate whether it is realistic to get a continuous HR sensor for livestock that can be used for long term monitoring. The review provides the reported techniques to monitor HR of living organisms by emphasizing their principles, advantages, and drawbacks. Various properties and capabilities of these techniques are compared to check the potential to transfer the mostly adequate sensor technology of humans to livestock in term of application. Based upon this review, we conclude that the photoplethysmographic (PPG) technique seems feasible for implementation in livestock. Therefore, we present the contributions to overcome challenges to evolve to better solutions. Our study indicates that it is realistic today to develop a PPG sensor able to be integrated into an ear tag for mid-sized and larger farm animals for continuously and accurately monitoring their HRs

Overview of 2015 International Symposium on Animal Environment and Welfare held in Chongqing, China

On October 24-25, 2015 International Symposium on Animal Environment and Welfare (ISAEW2015), jointly sponsored by the International Research Center for Animal Environment and Welfare (IRCAEW) and the Chinese Society of Agricultural Engineering, was convened in Chongqing Academy of Animal Sciences (CAAS), Chongqing, China. Prof. Baoming Li from China Agricultural University (CAU) and Distinguished Prof. Hongwei Xin from Iowa State University were the Co-Chairs of ISAEW2015, and Prof. Zuohua Liu from CAAS chaired the Organizing Committee. Prof. Jun Bao, President of Northeast Agriculture University, China, presided over the opening ceremony. Prof. Xiwen Luo, an Academician of Chinese Academy of Engineering, presented the challenges and shared his thoughts on the sustainable development of animal production industry in China in the opening remarks.This article is from International Journal of Agricultural and Biological Engineering 8 (2015): 179–180.</p

Effect of Stocking Density on Behavior and Pen Cleanliness of Grouped Growing Pigs

In recent years, animal cleanliness during production has gradually attracted increasing attention. Although pigs by nature tend to excrete in dark and humid corners, in the prevalent highly intensive pig production, excessive stocking density often restricts the ability of pigs to excrete at designated points, thereby leading to pollution of the pens. To study the effect of stocking density on pen cleanliness and the relevant pig behavior, a total of 216 Landrace × Yorkshire × Duroc hybrid pigs were randomly grouped at 0.5, 0.7, or 0.9 m2 per pig at 59 ± 3 days of age. The temporal and spatial distributions of lying and excreting behavior of pigs were monitored on days 1, 7, and 35 after transfer, and the cleanliness of pig pens under three stocking densities was scored. The results showed that there were no significant differences in excreting or lying time rhythms among the three treatments. In the initial and stable periods of group transfer, the excretion rate of pigs on slatted floors was significantly higher than that on solid floors at 0.9 m2/pig (p 2/pig was 10.81%, that is, 7.43% higher than that of 0.7 m2/pig, and the differences were significant. Judging from the pollution score of the solid floors, the three stocking densities all showed more serious pollution at the corners, and the pollution score of the pens with a density of 0.9 m2/pig was lower than that of the pens with a density of 0.5 and 0.7 m2/pig. The analysis of whether pigs had corresponding behaviors in specific functional areas showed that pigs at a density of 0.9 m2/pig had a 10.14% lower lying rate on slatted floors (the expected excretion area) than on solid floors, whereas the densities of 0.5 and 0.7 m2/pig showed the opposite pattern. Pigs at a density of 0.9 m2/pig had lower excretion rates in both corners of the solid floors (the desired lying area) than that of the 0.5 m2/pig group (p 2/pig group (p > 0.05). These results indicate that when the effective occupied space of pigs was larger, specific behaviors were more likely to occur in the set functional areas, and the cleanliness of the pen was higher. Under the conditions of this experiment, the recommended stocking density for growing pigs was 0.9 m2/pig. Of course, a larger space may be more beneficial to animal health and welfare, but the economic costs must also be considered

An effective approach to activate 316L stainless steel for biomimetic coating of calcium phosphate: electrochemical pretreatment

In this paper, an electrochemical (EC) method to activate 316L stainless steel (denoted as 316L) surface for biomimetic calcium phosphate (Ca-P) coatings was reported. After EC treatment, a gel-like Ca-P film with a thickness of 150 nm was generated on the stainless steel surface after treatment, which was composed of amorphous phase of calcium phosphate with a large number of crystal nuclei of octacalcium phosphate (OCP) inside. This Ca-P thin film is the main factor that causes Ca-P formation under biomimetic condition. The effectiveness of EC treatment was also compared with alkali heat (AH) pretreatment in producing biomimetic coating on 316L. A uniform Ca-P coating formed on EC treated samples after samples were immersed in saturated calcium solution (SCS) for several hours, while only some island-like deposits were found on the sample surface with AH treatment followed by immersion in SCS for several days. This work has explored a novel and effective pretreatment method to activate 316L implant surface, which can be expected to be applied to activate other metal implants