Search

Understanding environmental determination of crop yield plays a critical role in agricultural. management in resource-limited areas. The climatic transition zone was a naturally ideal place to study. the relations between environmental factors and crop yield, due to its large annual variability of climatic factors and high speed of temperature increase under global warming. Our objectives were to identify the most critical environmental factor in determining spring wheat yield and analyze the convergence and divergence of water-yield relations for spring wheat in a typical climatic transition zone (semi-arid area). The study was conducted at two locations, Dingxi and Pengyang in Northwest China, with a long-term experiment (1987-2018) and two short-term irrigation experiments. Meanwhile, data of water use and spring wheat yield was collected from a series of previously published literature in the study area. The highest spring wheat yield was obtained under year pattern with higher soil water content at sowing (SWCS) and lower atmospheric dryness condition (ADC, the difference between reference evapotranspiration and precipitation during spring wheat growing season). SWCS was more important than precipitation during the growing season (PGS) in determining spring wheat yield in the study area. The relations between available water supply, water use, and spring wheat yield were convergence. However, SWCS had an impact on the relationship between yield and PGS and SWCS-yield relation was affected by ADC. We concluded that precipitation in 7 months before sowing was the dominant factor determining spring wheat yield in the climatic transition zone under global warming whereas the impact of high atmospheric evaporative demand resulted from the increasing temperature on crop yields and SWCS-yield relation must be taken into account for the analysis of environmental determination of spring wheat yield.

Low modulus materials that can shape-morph into different three-dimensional (3D) configurations in response to external stimuli have wide-ranging applications in flexible/stretchable electronics, surgical instruments, soft machines and soft robotics. This paper reports a shape-programmable system that exploits liquid metal microfluidic networks embedded in an elastomer matrix, with electromagnetic forms of actuation, to achieve a unique set of properties. Specifically, this materials structure is capable of fast, continuous morphing into a diverse set of continuous, complex 3D surfaces starting from a two-dimensional (2D) planar configuration, with fully reversible operation. Computational, multi-physics modeling methods and advanced 3D imaging techniques enable rapid, real-time transformations between target shapes. The liquid-solid phase transition of the liquid metal allows for shape fixation and reprogramming on demand. An unusual vibration insensitive, dynamic 3D display screen serves as an application example of this type of morphable surface.

Piezoelectric microsystems are of use in areas such as mechanical sensing, energy conversion and robotics. The systems typically have a planar structure, but transforming them into complex three-dimensional (3D) frameworks could enhance and extend their various modes of operation. Here, we report a controlled, nonlinear buckling process to convert lithographically defined two-dimensional patterns of electrodes and thin films of piezoelectric polymers into sophisticated 3D piezoelectric microsystems. To illustrate the engineering versatility of the approach, we create more than twenty different 3D geometries. With these structures, we then demonstrate applications in energy harvesting with tailored mechanical properties and root-mean-square voltages ranging from 2 mV to 790 mV, in multifunctional sensors for robotic prosthetic interfaces with improved responsivity (for example, anisotropic responses and sensitivity of 60 mV N−1 for normal force), and in bio-integrated devices with in vivo operational capabilities. The 3D geometries, especially those with ultralow stiffnesses or asymmetric layouts, yield unique mechanical attributes and levels of functionality that would be difficult or impossible to achieve with conventional two-dimensional designs. Nonlinear buckling processes can be used to transform thin films of piezoelectric polymers into sophisticated 3D piezoelectric microsystems with applications in energy harvesting, multifunctional sensing and bio-integrated devices.

Hydrocephalus is a common disorder caused by the buildup of cerebrospinal fluid (CSF) in the brain. Treatment typically involves the surgical implantation of a pressure-regulated silicone tube assembly, known as a shunt. Unfortunately, shunts have extremely high failure rates and diagnosing shunt malfunction is challenging due to a combination of vague symptoms and a lack of a convenient means to monitor flow. Here, we introduce a wireless, wearable device that enables precise measurements of CSF flow, continuously or intermittently, in hospitals, laboratories or even in home settings. The technology exploits measurements of thermal transport through near-surface layers of skin to assess flow, with a soft, flexible, and skin-conformal device that can be constructed using commercially available components. Systematic benchtop studies and numerical simulations highlight all of the key considerations. Measurements on 7 patients establish high levels of functionality, with data that reveal time dependent changes in flow associated with positional and inertial effects on the body. Taken together, the results suggest a significant advance in monitoring capabilities for patients with shunted hydrocephalus, with potential for practical use across a range of settings and circumstances, and additional utility for research purposes in studies of CSF hydrodynamics.

Purpose B-cell translocation gene 3 (BTG3) has been identified as a candidate driver gene for various cancers, but its specific role in colorectal cancer (CRC) is poorly understood. We aimed to investigate the relationship between expression of BTG3 and clinicopathological features and prognosis, as well as to explore the effects and the role of a possible BTG3 molecular mechanism on aggressive colorectal cancer behavior. Methods BTG3 expression was assessed by immunohistochemistry (IHC) on specimens from 140 patients with CRC. The association of BTG3 expression with clinicopathological features was examined. To confirm the biological role of BTG3 in CRC, two CRC cell lines expressing BTG3 were used and BTG3 expression was knocked down by shRNA. CCK-8, cell cycle, apoptosis, migration, and invasion assays were performed. The influence of BTG3 knockdown was further investigated by genomic microarray to uncover the potential molecular mechanisms underlying BTG3-mediated CRC development and progression. Results BTG3 was downregulated in colorectal cancer tissues and positively correlated with pathological classification (p = 0.037), depth of invasion (p = 0.016), distant metastasis (p = 0.024), TNM stage (p = 0.007), and overall survival (OS) and disease-free survival (DFS). BTG3 knockdown promoted cell proliferation, migration, invasion, relieved G2 arrest, and inhibited apoptosis in HCT116 and LoVo cells. A genomic microarray analysis showed that numerous tumor-associated signaling pathways and oncogenes were altered by BTG3 knockdown. At the mRNA level, nine genes referred to the extracellular-regulated kinase/mitogen-activated protein kinase pathway were differentially expressed. Western blotting revealed that BTG3 knockdown upregulated PAK2, RPS6KA5, YWHAB, and signal transducer and activator of transcription (STAT)3 protein levels, but downregulated RAP1A, DUSP6, and STAT1 protein expression, which was consistent with the genomic microarray data. Conclusions BTG3 expression might contribute to CRC carcinogenesis. BTG3 knockdown might strengthen the aggressive colorectal cancer behavior.

To better understand the characterization and secondary organic aerosol (SOA) formation of volatile organic compounds (VOCs) during non-haze and haze days, ambient VOCs were continuously measured by a vehicle-mounted online thermal desorption system coupled with a gas chromatography–mass spectrometry (TD–GC/MS) system in Shanghai, China. The average concentrations of VOCs in haze episodes (193.2 μg m−3) were almost 50% higher than in non-haze periods (130.8 μg m−3). VOC concentrations exhibited a bi-modal pattern in the morning and evening rush hour periods on both non-haze and haze days. The ratios of toluene to benzene (T/B) and m,p-xylene to ethylbenzene (X/E) indicated that VOCs were aged air mass transported from nearby areas. The estimated SOA yields were 12.6 ± 5.3 and 16.7 ± 6.7 μg m−3 for non-haze and haze days, respectively, accounting for 9.6 and 8.7% of the corresponding PM2.5 concentrations, which were slightly underestimated. VOCs–sensitivity (VOCs–S) based on a PM2.5-dependent model was used to investigate the variation between VOCs and PM2.5 concentrations in the morning rush hour. It was found that VOCs were more sensitive to PM2.5 on clean days than during periods of heavy particulate pollution. VOCs–sensitivity was significantly correlated with the ratio of specific PM2.5 to background PM2.5, with a simulated equation of y = 0.84x−0.62 (r 2 = 0.93, p

Through dimension analysis, an almost analytical model for the maximum diffusion induced stress (DIS) and critical temperature (or concentration) difference at which cracks begin to initiate in the diffusion process is developed. It interestingly predicts that the spacing of diffusion-induced cracks is constant, independent of the thickness of specimen and the temperature difference. These conclusions are validated by our thermal shock experiments on alumina plates. Furthermore, the proposed model can interpret observed hierarchical crack patterns for high temperature jump cases, and a three-stage relation between the residual strength and the temperature difference. The prediction for crack spacing can guide the biomimetic thermal-shock-failure proof design, in which the hard platelets smaller than the predicted diffusion induced by constant crack-spacing are embedded in a soft matrix, and, therefore, no fracture will happen. This may guide the design of the thermal protection system and the lithium ion battery. Finally we present the maximum normalized DISes for various geometry and boundary conditions by single-variable curves for the stress-independent diffusion process and two-variable contour plots for the stress-dependent diffusion process, which can provide engineers and materialists a simple and easy way to quickly evaluate the reliability of related materials and devices.

The heat storage terms over an ideal (non-vegetated) horizontal desert surface may be very important and easily neglected in surface energy balance studies. In this paper, based on a field experiment over the Gobi Desert in the middle part of the Hexi Corridor in Northwest China (39°05′N, 100°16′E; 1457-m elevation), we studied the energy budget closure and evaluated the contribution of the heat storage terms to the closure of the surface energy balance. There were imbalances of 8% and 15% in summer and winter, respectively, if the heat storage terms were not taken into account. For both seasons, a nearly perfect result of the surface energy closure (99%) was obtained by inclusion of the estimates of heat storage terms. The soil heat storage term improved the surface energy imbalance by about 6% in summer and 13% in winter, and the air enthalpy storage term improved it by about 0.6% in summer and 1% in winter, while the contribution of the atmospheric moisture changes could be ignored.

A simulated warming manipulation was conducted to evaluate the effects of temperature increase on cadmium (Cd), lead (Pb), copper (Cu), iron (Fe) and zinc (Zn) accumulation in Solanum tuberosum L. at Dingxi, Gansu, in the semiarid northwest of China. The objective of this study was to determine if temperature increases significantly changed trace element concentrations and contents in the different ecosystem compartments by affecting soil content, soil solubility and plant capture. The results reveal that an increase in temperature will lead to a significant change in trace element concentrations and contents in Solanum tuberosum L. The strongest effects of a 3°C temperature increase are increased Cu, Zn and Fe leaf concentrations of 25, 27 and 24%, respectively; but decreases in Cd, Pb, Fe, Zn and Cu tuber concentrations of 27, 55, 41, 29 and 23%, respectively. The increasing concentrations of some trace elements in Solanum tuberosum L. leaves are related to greater retranslocation, photosynthetic capacity and growth. Warming decreases the concentrations of some trace elements in tubers, implying that tuber growth rate exceeds its metal uptake rate at higher temperatures. Indeed, it is expected that by the year 2050 the increased temperature will have induced a decrease of concentrations of Cd, Pb, Cu, Fe and Zn of 9.1, 11.5, 18.5, 16.8 and 15.8%, respectively, in tubers in the study area. In addition, the results indicate that a 1–3°C increase in temperature will improve the availability of selected trace elements and transfer potential of these elements from soil to Solanum tuberosum L.