Ecological stoichiometry and homeostasis characteristics of plant-litter-soil system with vegetation restoration of the karst desertification control

It is of great significance to clarify the ecologically chemical stoichiometric characteristics of plant-litter-soil in vegetation restoration process for elucidating the nutrient cycling law and soil nutrient management of karst ecosystem. The carbon (C), nitrogen (N) and phosphorus (P) contents of leaves, litter and soil and their stoichiometry were determined in loquat (Eribotrya japonica) plantations in a karst plateau canyon after 3, 6, 10 and 15 years of restoration. The homeostasis characteristics of leaf N, P, and N:P with the change in soil nutrients during restoration were revealed. The results showed that leaf C, N, and P contents initially increased and then decreased with increasing years of restoration at the same sampling time. The contents of nutrients in soil and litter varied with increasing restoration years, with the highest values mostly appearing in May and July. This could be due to greater moisture in May and July, which helps with nutrient absorption and transformation. The leaf N:P ratio of loquat with different restoration years was 35.76-47.39, with an average of 40.06. Therefore, loquat leaves may experience P limitation in the growth process. The relationships between N, P and N:P in leaves and soil indexes could be simulated by a homeostasis model. Except for the weak sensitivity of loquat leaf N in 10 years, the other indexes and treatments had a certain homeostasis. Plants maintain homeostasis by regulating physiological responses in vivo in response to soil nutrient changes, indicating that loquat has good adaptability in karst desertification environments, but attention should focus on the management of soil P in the field as part of the vegetation restoration process. Therefore, in future research, we should combine the soil water and fertilizer conditions of different growing seasons in karst rocky desertification areas and provide scientific field management to ensure that the results of rocky desertification management can play a role in rural revitalization

Effect of Mixed Cooling on Postmortem Energy Metabolism and Meat Quality of Yellow-Feathered Broilers

In order to investigate the effect of low-temperature air cooling on the postmortem energy metabolism and meat quality of yellow-feathered broilers during mixed cooling (first water cooling and then air cooling), 85-day-old broilers were slaughtered and divided into three groups: treatment (water cooling at 0–4 ℃ followed by air cooling at −8, −18, −25 or −31 ℃), control (traditional water cooling at 0–4 ℃) and traditional mixed cooling (water cooling at 0–4 ℃ followed by air cooling at 0–4 ℃) groups. Finally, all carcasses were cooled to an internal temperature of 4 ℃, and the optimal air cooling temperature was determined by measuring cooling rate, pH, energy metabolism and quality indexes. The results showed that the cooling time of air cooling at −25 and −31 ℃ was 2 537 and 2 272 s, respectively, which was shortened by 27.78% and 35.33% compared with the traditional water cooling and by 51.87% and 56.90% compared with the traditional mixed cooling, respectively. Air cooling at −25 and −31 ℃ delayed the decrease in pH, reduced the drip loss and cooking loss of broiler breast muscle, significantly increased the shear force and the content of immobilized water compared with the control group (P < 0.05). Compared with the other groups, the activities of muscle hexokinases, phosphate-3-phosphate dehydrogenase and lactate dehydrogenase in the air cooling treatments at −25 and −31 ℃ were lower, and the consumptions of adenosine triphosphate (ATP) and glycogen, the production of lactic acid and adenosine monophosphate (AMP) and AMP/ATP ratio were the smallest (P < 0.05). The above findings showed that air cooling at −25 and −31 ℃ significantly inhibited the rate of anaerobic glycolysis during the early postmortem period in chicken meat, delayed the rate of pH decline, and effectively improved muscle water retention. From the perspective of industrial energy saving, −25 ℃ is determined as the best temperature for air cooling treatment

Nanobubbles for enhanced ultrasound imaging of tumors

The fabrication and initial applications of nanobubbles (NBs) have shown promising results in recent years. A small particle size is a basic requirement for ultrasound contrast-enhanced agents that penetrate tumor blood vessel pores to allow for targeted imaging and therapy. However, the nanoscale size of the particles used has the disadvantage of weakening the imaging ability of clinical diagnostic ultrasound. In this work, we fabricated a lipid NBs contrast-enhanced ultrasound agent and evaluated its passive targeting ability in vivo. The results showed that the NBs were small (436.8 ± 5.7 nm), and in vitro ultrasound imaging suggested that the ultrasonic imaging ability is comparable to that of microbubbles (MBs). In vivo experiments confirmed the ability of NBs to passively target tumor tissues. The NBs remained in the tumor area for a longer period because they exhibited enhanced permeability and retention. Direct evidence was obtained by direct observation of red fluorescence-dyed NBs in tumor tissue using confocal laser scanning microscopy. We have demonstrated the ability to fabricate NBs that can be used for the in vivo contrast-enhanced imaging of tumor tissue and that have potential for drug/gene delivery

Heated Area and Well Performance Analysis of Injection N2 and CO2 in Cycle Steam Stimulation Process

Application of steam injection technology to heavy oil reservoirs is the most commercially successful EOR method. Cycle steam stimulation (CSS) is known as the most widely used and mature technology compared with various thermal methods. Because of various reasons, such as too high initial oil viscosity, excessive overburden heat loss and so on, in CSS, the radius of heated zone is small and the viscosity of heavy oil still cannot be lowered effectively, which leads to the low oil productivity and poor oil well performance. A variation on CSS process is to add N2 and CO2 in steam injection. Because of the influence of the N2 and CO2, the heated area and well performance of N2 and CO2 assisted CSS are different from that of steam stimulation. Therefore, this paper describes a detailed study of N2 and CO2 influence to cycle steam stimulation. In this paper, the physical simulation experiments of N2 and CO2 influence to the mixture of heavy oil are carried out at first. Through physical experiments, the enhancing oil mechanisms of N2 and CO2,the recovery mechanism of reducing oil viscosity by CO2 dissolving, reducing interfacial tension between gas and heavy oil, which are different from the steam, are described respectively. Based on this, a numerical simulation model with a single horizontal well is built to carry out the quantitative and comparative study of heated area of formation. Results show that the development effect of N2 and CO2 assisted CSS is better than that of conventional steam stimulation in porous media. Next, the different well performance of the N2 and CO2 assisted CSS and conventional CSS are compared by numerical results. Finally, on the basis of the field data of two different heavy oil field, two typical wells of CSS and N2 and CO2 assisted CSS are analyzed in detail. Consequently, the N2 and CO2 injection together with steam is helpful to improve development effect in CSS process

Unsupervised Multi-resident Tracking in Smart Environments

Aging is a global challenge that our society will face in the next few decades. Smart environment and ambient assisted living (AAL) offer promising technologies to help people stay active, socially connected, and independent into older age. Ambient binary sensors, such as PIR motion sensors, magnetic door sensors, and contact-based item sensors, offer a low cost, easy to deploy and unobtrusive solution to constructing a smart environment. However, the limited ability of coping with multiple residents in a smart environment hinders widespread adoption of the AAL and smart environment technologies.In this dissertation, we investigate the multi-resident tracking problem in smart environments equipped with ambient binary sensors. First, we establish the theoretical foundation of the hypothesis that human daily indoor mobility is predictable. Based on information theory, we derive an upper bound of predictability using sensor events recorded in over 100 smart homes.In addition, we formulate the multi-resident tracking (MRT) problem in the framework of finite set statistics (FISST) and propose a sensor-vectorized MRT solution, sMRT. In sMRT, the resident movement in the smart environment is mapped to a point target maneuvering in a latent measurement space. The sensors are mapped into the vectors of the measurement by mining the spatio-temporal relation exhibited in the recorded sequence. Furthermore, we propose sMRT-ML by introducing an unsupervised learning procedure to derive the model parameters previously treated as hyper-parameters in sMRT. We also introduce a track consistency optimization procedure to reduce target mismatch errors during tracking.Our proposed sMRT and sMRT-ML algorithms are evaluated using sensor events collected in two multi-resident smart homes. The ground truth labels are provided by an external annotator using a visualization tool, ActViz, that we specifically designed for this research. Experimental results shows promising performance of sMRT and sMRT-ML in comparison with baseline algorithms which rely on the smart environment floor plans and sensor locations to associate sensor events with residents

Visualization of DNA Damage and Protection by Atomic Force Microscopy in Liquid

DNA damage is closely related to cancer and many aging-related diseases. Peroxynitrite is a strong oxidant, thus a typical DNA damage agent, and is a major mediator of the inflammation-associated pathogenesis. For the first time, we directly visualized the process of DNA damage by peroxynitrite and DNA protection by ectoine via atomic force microscopy in liquid. We found that the persistence length of DNA decreases significantly by adding a small amount of peroxynitrite, but the observed DNA chains are still intact. Specifically, the persistence length of linear DNA in a low concentration of peroxynitrite (0 &micro;M to 200 &micro;M) solution decreases from about 47 nm to 4 nm. For circular plasmid DNA, we observed the enhanced superhelices of plasmid DNA due to the chain soften. When the concentration of peroxynitrite was above 300 &micro;M, we observed the fragments of DNA. Interestingly, we also identified single-stranded DNAs during the damage process, which is also confirmed by ultraviolet spectroscopy. However, if we added 500 mM ectoine to the high concentration PN solution, almost no DNA fragments due to double strand breaks were observed because of the protection of ectoine. This protection is consistent with the similar effect for DNA damage caused by ionizing radiation and oxygenation. We ascribe DNA protection to the preferential hydration of ectoine