Export restrictions on metals and mineral products have been broadly applied by many countries with a view to securing domestic supply and addressing resource depletion. Export restrictions are ...designed to meet diverse policy objectives ranging from environmental protection and increasing fiscal revenue to the development of processing sectors. The global dependency on China for raw materials (particularly rare earth elements) is a contentious issue, as China imposes a number of restrictions on the export of these minerals. This study uses the case of rare earth elements to evaluate Chinese export restrictions, reviewing China's current monopoly over the industry and providing insights on how widely traded these minerals are and China's position in international trade in terms of both volume and value. The study investigates the various trade restrictions imposed by China and their implications, including the availability of materials to industrialized countries.
•Global rare earth minerals trade and China's trade volume/value are evaluated.•China's export restrictions on such minerals and their effects are studied.•No evidence exists that China's restrictions had desired effects on production.•Rare earth minerals are a major factor of China's industrial growth.
•Effects of Chinese policies on resilience of REE supply chain are evaluated.•International trade laws, new investments and illegal mining are identified as resilience promoting ...mechanisms.•International standard, Chinese imports of REEs, stockpiling and environmental regulations tend to demote resilience.•REE prices are largely dependent on Chinese national policies.
Rare earths elements (REE) are considered as strategic resources because they interact with business and governments’ direct policy interventions. Policy interventions can have a major effect on security of rare earth supply (Kooroshy et al., 2015). The purpose of this study is to scrutinize China’s REE policies and its impacts on the supply chain resilience. We analyze the supply chain dynamics by specifically targeting a number of Chinese REE policies that have disruptive tendencies. We analyze various policies placing the price at the center as an overarching feedback loop. In other words, we focus on how price responds to various resilience influencing mechanisms such as diversity of supply, regulatory frameworks, and stockpiling. In the process, we investigate Chinese influence on rest of the world (RoW) supply chain and dynamics inside the Chinese supply chain as there are two different layers of supply chain one for China and another one for rest of the world. We show that the supply chain is a complex phenomenon and resilience of a system is not solely dependent on physical disruptions but also on dynamic factors such as societal and geo-political (eg. environmental regulation, speculative market and export ban). We identify links and interdependencies even where data is not readily available and examine how the overall system reacts to various constraints and disruptions.
Proposed and experimentally demonstrated is the linear low contrast detection capability of a smart design Coded Access Optical Sensor (CAOS) camera operating under interfering bright light ...conditions. This fine contrast imaging capability is delivered by engaging both the silicon CMOS sensor-mode of the constructed smart CAOS camera and deploying spatial filtering within its inherent on/off light routing structure via the Digital Micromirror Device (DMD). The camera uses the CMOS-mode identified non-bright light region of interest to engage the Code-Division Multiple Access (CDMA) CAOS-mode to achieve successful target imaging. Specifically, the low contrast variation (< 6 dB dynamic range) test target region of the toy horse target is successfully experimentally imaged within a near 87 dB High Dynamic Range (HDR) scene created by the presence of an external interfering bright visible light source. Applications scenarios that can benefit from the use of the proposed camera include natural bright light conditions surveillance as well as bright laser and LED targeted imaging across medical, industrial and scientific sectors.
Performance trade offs for achieving high torque density and high drive-cycle efficiency in spoke-type permanent magnet (PM) motors are investigated. Unlike the traditional method, which relies on ...analytical equations, this trade-off study is conducted through a statistical analysis of the Pareto-optimal design candidates resulting from a large-scale design optimization of an example traction machine over a Le Mans-based drive cycle. In the design optimization process, both low-speed and extended-speed/field-weakening operating regions are evaluated using high-fidelity electromagnetic finite element (FE) simulations with an objective to simultaneously increase the torque density and decrease the power losses over the high energy-throughput-zones of the machine torque-speed plane. The resultant 3400 design candidates are utilized to investigate the impact of increasing power density on other important performance metrics such as power losses, PM demagnetization, and torque ripple. This analysis is supplemented by multiphysics simulation of three counterpart optimized designs and successful experimental verification of a prototype of one of those three designs which represents a record high power density motor in traction applications.
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•Engineering properties of FAGP and AAS concrete have been investigated.•The FAGP concrete has been produced by blending an alkaline activator with FA.•The AAS concrete has been ...produced by blending an alkaline activator with GGBFS.•The FAGP concrete has been produced using heat curing at 80 °C for 24 h.•The AAS has been produced at ambient curing condition.
Fly ash-based geopolymer (FAGP) and alkali-activated slag (AAS) concrete are produced by mixing alkaline solutions with aluminosilicate materials. As the FAGP and AAS concrete are free of Portland cement, they have a low carbon footprint and consume low energy during the production process. This paper compares the engineering properties of normal strength and high strength FAGP and AAS concrete with OPC concrete. The engineering properties considered in this study included workability, dry density, ultrasonic pulse velocity (UPV), compressive strength, indirect tensile strength, flexural strength, direct tensile strength, and stress-strain behaviour in compression and direct tension. Microstructural observations using scanning electronic microscopy (SEM) are also presented. It was found that the dry density and UPV of FAGP and AAS concrete were lower than those of OPC concrete of similar compressive strength. The tensile strength of FAGP and AAS concrete was comparable to the tensile strength of OPC concrete when the compressive strength of the concrete was about 35 MPa (normal strength concrete). However, the tensile strength of FAGP and AAS concrete was higher than the tensile strength of OPC concrete when the compressive strength of concrete was about 65 MPa (high strength concrete). The modulus of elasticity of FAGP and AAS concrete in compression and direct tension was lower than the modulus of elasticity of OPC concrete of similar compressive strength. The SEM results indicated that the microstructures of FAGP and AAS concrete were more compact and homogeneous than the microstructures of OPC concrete at 7 days, but less compact and homogeneous than the microstructures of OPC concrete at 28 days for the concrete of similar compressive strength.
•Geopolymer concrete with GGBFS has been produced at ambient curing condition.•GGBFS improved early strength development of geopolymer concrete.•Compressive strength reduced for partial replacement ...of GGBFS with FA, MK, and SF.•Setting time increased for partial replacement of GGBFS with FA, MK, and SF.•Workability increased for partial replacement of GGBFS with FA, MK, and SF.
In this paper, the Taguchi method has been used to design optimum mix proportions for geopolymer concrete with ground granulated blast furnace slag (GGBFS) as aluminosilicate source at ambient curing condition. The influences of binder content, alkaline activator to binder content (Al/Bi) ratio, sodium silicate to sodium hydroxide (SS/SH) ratio, and sodium hydroxide (SH) concentration on the geopolymer concrete were investigated. A total of nine mix designs were evaluated. It was found that specimens with a binder content of 450kg/m3, Al/Bi ratio of 0.35, SS/SH ratio of 2.5, and SH concentration of 14M produced the highest 7-day compressive strength (60.4MPa). However, the setting time was found to be short. Hence, fly ash (FA), metakaolin (MK), and silica fume (SF) were used as partial replacement of GGBFS in different proportions to increase the setting time. It was found that the setting time improved for the partial replacement of GGBFS with FA, MK, and SF.
On-line condition monitoring is of paramount importance for multilevel power converters used in safety-critical applications. A novel on-line nonintrusive diagnostic method for detecting open-circuit ...switch faults in silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs)-based T-type multilevel converters is introduced in this paper. The principle of this method is based on monitoring the abnormal variations of the dc-bus neutral-point current in combination with the existing information on instantaneous switching states and phase currents. Advantages of this method include faster detection speed and simpler implementation compared to other existing diagnostic methods in the literature. Moreover, this diagnostic method is immune to the disturbances of inverter's dc-bus voltage unbalance and load unbalance. In this method, only one additional current sensor is required for measuring the dc-bus neutral-point current; therefore, the implementation cost is low. Simulation and experimental results based on a lab-scale 20 kVA adjustable speed drive with a three-level SiC T-type inverter validate the effectiveness and robustness of this novel diagnostic method.
Intragenomic conflicts arise when a genetic element favours its own transmission to the detriment of others. Conflicts over sex chromosome transmission are expected to have influenced genome ...structure, gene regulation, and speciation. In the mouse, the existence of an intragenomic conflict between X- and Y-linked multicopy genes has long been suggested but never demonstrated. The Y-encoded multicopy gene Sly has been shown to have a predominant role in the epigenetic repression of post meiotic sex chromatin (PMSC) and, as such, represses X and Y genes, among which are its X-linked homologs Slx and Slxl1. Here, we produced mice that are deficient for both Sly and Slx/Slxl1 and observed that Slx/Slxl1 has an opposite role to that of Sly, in that it stimulates XY gene expression in spermatids. Slx/Slxl1 deficiency rescues the sperm differentiation defects and near sterility caused by Sly deficiency and vice versa. Slx/Slxl1 deficiency also causes a sex ratio distortion towards the production of male offspring that is corrected by Sly deficiency. All in all, our data show that Slx/Slxl1 and Sly have antagonistic effects during sperm differentiation and are involved in a postmeiotic intragenomic conflict that causes segregation distortion and male sterility. This is undoubtedly what drove the massive gene amplification on the mouse X and Y chromosomes. It may also be at the basis of cases of F1 male hybrid sterility where the balance between Slx/Slxl1 and Sly copy number, and therefore expression, is disrupted. To the best of our knowledge, our work is the first demonstration of a competition occurring between X and Y related genes in mammals. It also provides a biological basis for the concept that intragenomic conflict is an important evolutionary force which impacts on gene expression, genome structure, and speciation.
The dissection of complex traits of economic importance to the pig industry requires the availability of a significant number of genetic markers, such as single nucleotide polymorphisms (SNPs). This ...study was conducted to discover several hundreds of thousands of porcine SNPs using next generation sequencing technologies and use these SNPs, as well as others from different public sources, to design a high-density SNP genotyping assay.
A total of 19 reduced representation libraries derived from four swine breeds (Duroc, Landrace, Large White, Pietrain) and a Wild Boar population and three restriction enzymes (AluI, HaeIII and MspI) were sequenced using Illumina's Genome Analyzer (GA). The SNP discovery effort resulted in the de novo identification of over 372K SNPs. More than 549K SNPs were used to design the Illumina Porcine 60K+SNP iSelect Beadchip, now commercially available as the PorcineSNP60. A total of 64,232 SNPs were included on the Beadchip. Results from genotyping the 158 individuals used for sequencing showed a high overall SNP call rate (97.5%). Of the 62,621 loci that could be reliably scored, 58,994 were polymorphic yielding a SNP conversion success rate of 94%. The average minor allele frequency (MAF) for all scorable SNPs was 0.274.
Overall, the results of this study indicate the utility of using next generation sequencing technologies to identify large numbers of reliable SNPs. In addition, the validation of the PorcineSNP60 Beadchip demonstrated that the assay is an excellent tool that will likely be used in a variety of future studies in pigs.
Equity in access is one of the core goals of the Organ Procurement and Transplant Network (OPTN). However, disparities in liver transplantation have been described since the passage of the National ...Organ Transplant Act, which established OPTN in the 1980s. During the past few decades, several efforts have been made by the United Network for Organ Sharing (UNOS) to address disparities in liver transplantation with notable improvements in many areas. Nonetheless, disparities have persisted across insurance type, sex, race/ethnicity, geographic area, and age. African Americans have lower rates of referral to transplant centers, females have lower rates of transplantation from the liver waiting list than males, and public insurance is associated with worse posttransplant outcomes than private insurance. In addition, pediatric candidates and older adults have a disadvantage on the liver transplant waiting list, and there are widespread regional disparities in transplantation. Given the large degree of inequity in liver transplantation, there is a tremendous need for studies to propose and model policy changes that may make the liver transplant system more just and equitable.
https://www.wileyhealthlearning.com/Activity2/7277057/Activity.aspx?parentActivityId=0
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